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Sample records for layer chromatographic analysis

  1. Thin Layer Chromatographic Analysis of Beta-Lactam Antibiotics

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    Gabriel Hancu

    2013-08-01

    Full Text Available Purpose: The paper describes some thin layer chromatographic procedures that allow simple and rapid separation and identification of penicillins and cephalosporins from complex mixtures. Methods: Using silicagel GF254 as stationary phase and selecting different mobile phases we succeeded in the separation of the studied beta-lactamins. Our aim was not only to develop a simple, rapid and efficient method for their separation but also the optimization of the analytical conditions. Results: No system will separate all the beta-lactams, but they could be identified when supplementary information is used from color reactions and/or by using additional chromatographic systems. Conclusions: The right combination of solvent system and detection method allows the identification of the studied penicillins and cephalosporins and can be successfully used in the preliminary analysis beta-lactam antibiotics.

  2. An improved method for thin layer chromatographic analysis of saponins.

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    Sharma, Om P; Kumar, Neeraj; Singh, Bikram; Bhat, Tej K

    2012-05-01

    Analysis of saponins by thin layer chromatography (TLC) is reported. The solvent system was n-butanol:water:acetic acid (84:14:7). Detection of saponins on the TLC plates after development and air-drying was done by immersion in a suspension of sheep erythrocytes, followed by washing off the excess blood on the plate surface. Saponins appeared as white spots against a pink background. The protocol provided specific detection of saponins in the saponins enriched extracts from Aesculusindica (Wall. ex Camb.) Hook.f., Lonicera japonica Thunb., Silene inflata Sm., Sapindusmukorossi Gaertn., Chlorophytum borivilianum Santapau & Fernandes, Asparagusadscendens Roxb., Asparagus racemosus Willd., Agave americana L., Camellia sinensis [L.] O. Kuntze. The protocol is convenient, inexpensive, does not require any corrosive chemicals and provides specific detection of saponins.

  3. Thin layer chromatographic separation of cobalt from nickel on impregnated silica gel layers:quantitative determination by digital image analysis%Thin layer chromatographic separation of cobalt from nickel on impregnated silica gel layers: quantitative determination by digital image analysis

    Institute of Scientific and Technical Information of China (English)

    P A MOHAMED NAJAR; R G SONALI; M T NIMJE; K V RAMANA RAO

    2012-01-01

    Thin layer chromatography (TLC) of cobalt and nickel has been performed on silica gel layers induced with alkali mediated cellulose extract.A novel combination of 10% aqueous solutions of Tween-20 and potassium thiocyanate in 1∶ 1 (v/v) was identified as the best mobile phase for the selective separation of Co2+ from Ni2+ on the impregnated Silica Gel G layers.The chromatographic characteristics of the cations were studied and the limits of detection as well as the limits of quantification for Co2+ and Ni2+ were determined.The quantitative estimation of the cations was achieved from the digital image analysis of respective chromatograms.The proposed quantitative method was successfully applied with 0-0.50% error for the determination of Co2+ from Ni2+ in spiked samples of bauxite,soil and rock containing common cations such as Al3+,Fe2+,Ti4+,Zn2+,Mn2+,Cu2+,Cr6+,Mg2+ etc.under the optimized chromatographic conditions.

  4. The effect of solvent grade on thin layer chromatographic analysis of writing inks.

    Science.gov (United States)

    Barker, Julia; Ramotowski, Robert; Nwokoye, Jennie

    2016-09-01

    The effects on the separation of writing ink dyes and the repeatability of the Rf values from using different grades of chemicals used in solvent system I (SSI) and solvent system II (SSII) for thin-layer chromatographic (TLC) ink analysis were studied. Solvent system I consists of a 70:35:30 mixture of ethyl acetate, ethanol, and water. Solvent system II consists of a 50:10:15 mixture of ethanol, water, and n-butanol. Since 1991, the ASTM International Guideline E 1422 has recommended that the purity of solvents should be "reagent grade" and that water quality should be "distilled or equivalent." A total of 25 blue and 25 black inks were selected for analysis. Thirteen of each color ink were ballpoint and the remainder were non-ballpoint. The observations show that there is a solvent grade effect on both the separation and clarity of the ink dyes and the repeatability of their Rf values. These results indicate that the grades and manufacturers of solvents used in solvent systems for thin-layer chromatography must be consistent. This is especially critical for searching TLC plates against those from a large ink library in casework. Overall, the combination of solvents that produced the best results for solvent system I consisted of denatured ethanol, HPLC grade water, and ACS grade ethyl acetate. There was no consensus for the best combination of solvent grades for solvent system II; however, it was shown that different grades did have an effect on the separation of ink components. Published by Elsevier Ireland Ltd.

  5. Thin layer chromatographic analysis of some common over the counter (OTC cough–cold preparations

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    Manpreet Kaur Chahal

    2016-12-01

    Full Text Available In the present study, potential utility of thin layer chromatography to differentiate some common OTC cough–cold preparations was evaluated. Twenty solvent systems were examined from which a solvent systems A comprising methanol:ammonia in the ratio of 100:1.5 (v/v and B comprising chloroform:methanol in the ratio of 90:10 (v/v were found to be most suitable as it showed a high degree of separation of different components of these preparations. It was also found that iodine fuming technique is the best visualizing method for examining the TLC chromatograms of these drug samples prior to subsequent instrumental analysis.

  6. Thin layer chromatographic analysis of food colorants from three morphotypes of annatto (Bixa orellana L.

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    Hari Pada Seal

    2012-06-01

    Full Text Available This article describes a simple solvent extraction method for the extraction of colorants from the three morphotypes such as, (Morphotype-1 (M1, Morphotype-2 (M2, and Morphotype-3 (M3 of Annatto (Bixa orellana L. seeds, and their separation, vivid, and qualitative demonstration by thin-layer chromatography. Several solvent systems (hexane, chloroform, acetone, ethanol, and a mixed-solvent having composition of CHCl3/C2H5OH/CH3COOH (80:2:1 were applied for extraction of colored components. It was observed that a large portion of colorants was extracted by chloroform. Its effluent was deep brick red in color and transparent. Furthermore, various carrier solvent systems (Benzene-Ethyl acetate were used to separate the components from the extracts. Carrier solvent system with the ratio of 7:3 was found as superior solvent for chloroform extracts. Three colored-spots were observed for all morphotypes. Among them, the first one was yellow colored having very low polarity and the second and third spots were both redbrick colored having medium and higher polarity respectively. In addition, for M1 no colorless-spot was observed in low and medium polar systems, revealing that the amount of wax and gum were minimum in the extract and superior morphotype among the three.

  7. Two-dimensional thin-layer chromatographic method for the analysis of ochratoxin A in green coffee.

    Science.gov (United States)

    Ventura, Meritxell; Anaya, Ivan; Broto-Puig, Francesc; Agut, Montserrat; Comellas, Lluís

    2005-09-01

    A low-cost thin-layer chromatographic method has been developed for the presumptive measurement of ochratoxin A (OTA) at 5 microg/kg in green coffee beans. The analytical method consisted of extracting OTA by shaking the beans with a mixture of methanol and aqueous sodium bicarbonate solution, which was then purified by liquid-liquid partition into toluene. OTA was separated by normal-phase two-dimensional thin-layer chromatography and detected by visual estimation of fluorescence intensity under a UV lamp at 365 nm. The chromatography solvents were toluene-methanol-formic acid (8:2:0.03) for the first development and petroleum ether-ethyl acetate-formic acid (8:10:1) for the second dimension development. This method was tested with uncontaminated green coffee bean samples spiked with an OTA standard at four different concentrations (5, 10, 20, and 30 microg/kg). The method is rapid, simple, and very easy to implement in coffee-producing countries. It is highly selective and does not involve the use of chlorinated solvents in the sample extraction step. This inexpensive method has been applied to different types of green coffee samples from various countries (Zimbabwe, Brazil, India, Uganda, Colombia, and Indonesia) and different manufacturers, and no OTA below the detection limit of 5 microg/kg was detected in any samples analyzed.

  8. Trilinear analysis of thin-layer chromatography retention of 35 model compounds chromatographed on nine adsorbents with 20 pure solvents.

    Science.gov (United States)

    Komsta, Łukasz; Skibiński, Robert; Bezpalko, Natalia; Mielniczek, Aleksandra; Stępkowska, Barbara

    2016-11-01

    The RF value dataset of 35 model compounds, chromatographed with 20 pure solvents as the mobile phase each on nine adsorbents: RP2, RP8, RP18, alumina, cellulose, CN, DIOL, NH2 , and silica, was subjected to trilinear analysis with parallel factor analysis. The two-factor optimal model explained 87% of total information in this complex dataset. The first obtained score (trend) represents two features: the presence of hydrogen bonding and heteroatoms of solute and the mean elution force of the solvent. The second trend represents molecule size, aromaticity, and number of carbons, interconnected with presence of chlorine in mobile phase. The correlation between the scores and molecular descriptors were checked to interpret these trends quantitatively. The scores of adsorbents were slightly intercorrelated, showing NH2 , alumina, and cellulose as outliers from main adsorbents cloud. The obtained results suggest that molecular size and aromaticity, connected with chlorine atoms in mobile phase, is the second source of retention variability.

  9. Metal-Organic Frameworks for Thin-Layer Chromatographic Applications.

    Science.gov (United States)

    Schenk, Claudia; Kutzscher, Christel; Drache, Franziska; Helten, Stella; Senkovska, Irena; Kaskel, Stefan

    2017-01-25

    Preparation of thin-layer chromatographic (TLC) plates based on metal-organic frameworks (MOFs) as porous stationary phases is described. DUT-67 (DUT = Dresden University of Technology), a zirconium based MOF, was used in combination with a fluorescent indicator as stationary phase for analyzing a small selection of a wide spectrum of relevant analytes. The successful separation of benzaldehyde from trans-cinnamaldehyde and 4-aminophenol from 2-aminotoluene is reported as a model system using optimized eluent mixtures containing acetic acid.

  10. Chromatographic fingerprint analysis of Pycnogenol dietary supplements.

    Science.gov (United States)

    Chen, Pei; Song, Fenhong; Lin, Long-Ze

    2009-01-01

    The bark of maritime pine (Pinus pinaster Aiton) has been widely used as a remedy for various degenerative diseases. A standard high-performance liquid chromatographic (HPLC) procedure for Pycnogenol analysis is a method specified in the United States Pharmacopeia (USP) monograph, which requires measurement of peak areas and identification of four components of the extract: caffeic acid, catechin, ferulic acid, and taxifolin. In this study, a fingerprint analysis using an HPLC method based on the USP monograph has been developed to provide additional qualitative information for the analysis of Pycnogenol-containing dietary supplements (PDS). Twelve commercially available PDS samples were purchased and analyzed along with a standard Pycnogenol extract. Their chromatographic fingerprints were analyzed using principal component analysis. The results showed that two of the samples were not consistent with the standard reference Pycnogenol extract. One contained other active ingredients in addition to Pycnogenol, and the other may have resulted from a quality control issue in manufacturing.

  11. Development and validation of a simple thin-layer chromatographic method for the analysis of p-chlorophenol in treated wastewater

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    Tešić Živoslav

    2012-01-01

    Full Text Available A thin-layer chromatographic method with densitometric detection was established for quantification of p-chlorophenol in waste water. Degradation efficiency of p-chlorophenol was monitored after each treatment of the wastewater samples. Degradation of p-chlorophenol was performed with advanced oxidation processes (AOPs, using UV, H2O2/UV, O3/H2O2/UV, O3 and O3/UV. Developed TLC procedure has been found to be simple, rapid and precise. The method was characterized by high sensitivity (limit of detection was 11 ng per band and limit of quantification 35 ng per band, linear range (from 75 to 500 ng per band, r = 0.9965, and high precision, accuracy (mean percentage recovery 98.6%, and specificity. Additionally, the efficiency of degradation was monitored using HPLC giving comparable results with RP TLC measurements. [Acknowledgement. This work was performed within the framework of the research project No. 172017 supported by the Ministry of Education and Science of Serbia.

  12. A contribution to the determination of aflatoxin B1, quinine hydrochloride and L(+)-ascorbic acid in foodstuffs by quantitative in situ thin-layer chromatographic analysis

    NARCIS (Netherlands)

    Beljaars, P.R.

    1974-01-01

    The application of quantitative thin-layer chromatography (TLC) involving in situ spectrodensitometric measurements with a flying-spot densitometer is described in this study for the analysis of aflatoxin B 1 , quinine hydrochloride

  13. A contribution to the determination of aflatoxin B1, quinine hydrochloride and L(+)-ascorbic acid in foodstuffs by quantitative in situ thin-layer chromatographic analysis

    NARCIS (Netherlands)

    Beljaars, P.R.

    1974-01-01

    The application of quantitative thin-layer chromatography (TLC) involving in situ spectrodensitometric measurements with a flying-spot densitometer is described in this study for the analysis of aflatoxin B 1 , quinine hydrochloride and L(+)-ascorbic acid (vitamin C

  14. Simple gas chromatographic method for furfural analysis.

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    Gaspar, Elvira M S M; Lopes, João F

    2009-04-03

    A new, simple, gas chromatographic method was developed for the direct analysis of 5-hydroxymethylfurfural (5-HMF), 2-furfural (2-F) and 5-methylfurfural (5-MF) in liquid and water soluble foods, using direct immersion SPME coupled to GC-FID and/or GC-TOF-MS. The fiber (DVB/CAR/PDMS) conditions were optimized: pH effect, temperature, adsorption and desorption times. The method is simple and accurate (RSDTOF-MS: 0.3, 1.2 and 0.9 ngmL(-1) for 2-F, 5-MF and 5-HMF, respectively). It was applied to different commercial food matrices: honey, white, demerara, brown and yellow table sugars, and white and red balsamic vinegars. This one-step, sensitive and direct method for the analysis of furfurals will contribute to characterise and quantify their presence in the human diet.

  15. Chromatographic separation studies of penicillins, cephalosporins and carbapenems on transition-metal silicate modified silica layers.

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    Singh, Dhruv K; Maheshwari, Gunjan

    2012-01-01

    The chromatographic behavior of penicillins, cephalosporins and carbapenems has been studied on the thin layers of transition-metal ion (viz. Ni(2+)/Zn(2+)/Cu(2+)/Co(2+)) silicate modified silica. Transition-metal silicate (3.92%) and silica (96.08%) were found to be optimum and resulted in spherical-compact spots and improved resolution of the analytes. The effect of various mobile phases was also investigated. The chromatograms were visualized as yellow spots by placing in an I(2)-chamber. The method has been found to be reproducible and convenient for routine analysis.

  16. High performance thin layer chromatographic method for simultaneous estimation of ibuprofen and pseudoephedrine hydrochloride

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    Chitlange S

    2008-01-01

    Full Text Available High performance thin layer chromatographic method is developed for simultaneous estimation of ibuprofen and pseudoephedrine hydrochloride in tablets. Silica gel 60F 254 plates were used as stationary phase and t.butanol: ethyl acetate: glacial acetic acid: water (7:4:2:2 v/v as mobile phase. Wavelength selected for analysis was 254 nm. Percent estimation of ibuprofen and pseudoephedrine hydrochloride was found to be 99.56% and 98.77%, respectively. Percent recovery for both the drugs was found in the range of 98.27% to 100.91%, respectively.

  17. Chromatographic Analysis of Inks for Forensic Science Applications.

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    Tebbett, I R

    1991-12-01

    This article reviews the use of chromatography for the separation and comparison of ink components. Thin layer chromatography (TLC) is the standard chromatographic procedure presently employed for the comparison of inks. Thin layer chromatography systems are described for the separation of different types of ink. The greater sensitivity and resolution offered by high performance liquid chromatography (HPLC) make it an attractive alternative to TLC for ink analysis, and recent work in this field is also outlined. Both techniques have been used for the measurement of changes occurring in the composition of inks with time, as a means of determining the age of an ink. Related analytical techniques, recent research, and future trends in ink analysis are also described. Copyright © 1991 Central Police University.

  18. Pharmacognostic screening of Piper trichostachyon fruits and its comparative analysis with Piper nigrum using chromatographic techniques

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    Vinayak Upadhya

    2016-01-01

    Abbreviation used: HPTLC: High Performance Thin Layer Chromatography, RP-UFLC: Reversed phase-ultra fl ow liquid chromatographic analysis, DST: Length of line, Maj: Length of large half axis for ellipse RDS - radius for circle, Rf: Retention Factor, TS: Transverse Section, TLC: Thin Layer Chromatography.

  19. Application of Microemulsions in Thin Layer Chromatographic Analysis of Amino Acids%十二烷基硫酸钠/正丁醇/正己烷/水 微乳液在氨基酸薄层色谱中的应用

    Institute of Scientific and Technical Information of China (English)

    田大听; 但悠梦; 王辉; 王联芝 王联芝; 谢洪泉

    2001-01-01

    The chromatographic behavior of twenty three amino acids on the silica gel thin layers us-ing sodium dodecylsulfate(SDS)/n-butyl alcohol/n-hexane/water microemulsion as a developer havebeen studied. The results showed that the W/O microemulsion and the bicontinuous microemulsioncomposed of the mentioned components appeared suitable developers for TLC analysis of amino acids.

  20. Multivariate assessment of lipophilicity scales-computational and reversed phase thin-layer chromatographic indices.

    Science.gov (United States)

    Andrić, Filip; Bajusz, Dávid; Rácz, Anita; Šegan, Sandra; Héberger, Károly

    2016-08-05

    Needs for fast, yet reliable means of assessing the lipophilicities of diverse compounds resulted in the development of various in silico and chromatographic approaches that are faster, cheaper, and greener compared to the traditional shake-flask method. However, at present no accepted "standard" approach exists for their comparison and selection of the most appropriate one(s). This is of utmost importance when it comes to the development of new lipophilicity indices, or the assessment of the lipophilicity of newly synthesized compounds. In this study, 50 well-known, diverse compounds of significant pharmaceutical and environmental importance have been selected and examined. Octanol-water partition coefficients have been measured with the shake-flask method for most of them. Their retentions have been studied in typical reversed thin-layer chromatographic systems, involving the most frequently employed stationary phases (octadecyl- and cyano-modified silica), and acetonitrile and methanol as mobile phase constituents. Twelve computationally estimated logP-s and twenty chromatographic indices together with the shake-flask octanol-water partition coefficient have been investigated with classical chemometric approaches-such as principal component analysis (PCA), hierarchical cluster analysis (HCA), Pearson's and Spearman's correlation matrices, as well as novel non-parametric methods: sum of ranking differences (SRD) and generalized pairwise correlation method (GPCM). Novel SRD and GPCM methods have been introduced based on the Comparisons with One VAriable (lipophilicity metric) at a Time (COVAT). For the visualization of COVAT results, a heatmap format was introduced. Analysis of variance (ANOVA) was applied to reveal the dominant factors between computational logPs and various chromatographic measures. In consensus-based comparisons, the shake-flask method performed the best, closely followed by computational estimates, while the chromatographic estimates often

  1. Hydrophilic interaction chromatographic analysis of anthocyanins.

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    Willemse, Chandré M; Stander, Maria A; de Villiers, André

    2013-12-06

    Hydrophilic interaction chromatography (HILIC) provides an alternative separation mode for the analysis of phenolic compounds, in which aqueous-organic mobile phases with polar stationary phases are used. This paper reports the evaluation of HILIC for the analysis of the natural pigments anthocyanins, which are of importance because of their chromophoric properties and a range of health benefits associated with their consumption. Several HILIC stationary phases (silica, diol, amine, cyanopropyl and amide) and mobile phase combinations were evaluated, with the latter proving particularly important due to the distinctive chromatographic behaviour of anthocyanins. Diode array detection was used for selective detection of anthocyanins, while high resolution quadrupole-time-of-flight mass spectrometry (Q-TOF-MS) was used for compound identification. The potential of HILIC separation is demonstrated for a range of anthocyanins varying in glycosylation and acylation patterns found in blueberries, grape skins, black beans, red cabbage and red radish. HILIC is shown to be a complementary separation method to reversed phase liquid chromatography (RP-LC) due to the alternative retention mechanism.

  2. Chromatographic analysis of olopatadine in hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Maksić, Jelena; Jovanović, Marko; Rakić, Tijana; Popović, Igor; Ivanović, Darko; Jančić-Stojanović, Biljana

    2015-01-01

    In this paper, chromatographic analysis of active substance olopatadine hydrochloride, which is used in eye drops as antihistaminic agent, and its impurity E isomer by hydrophilic interaction liquid chromatography (HILIC) and application of design of experiments (DoE) methodology are presented. In addition, benzalkonium chloride is very often used as a preservative in eye drops. Therefore, the evaluation of its chromatographic behavior in HILIC was carried out as well. In order to estimate chromatographic behavior and set optimal chromatographic conditions, DoE methodology was applied. After the selection of important chromatographic factors, Box-Behnken design was utilized, and on the basis of the obtained models factor effects were examined. Then, multi-objective robust optimization is performed aiming to obtain chromatographic conditions that comply with several quality criteria simultaneously: adequate and robust separation of critical peak pair and maximum retention of the first eluting peak. The optimal conditions are identified by using grid point search methodology. The experimental verification confirmed the adequacy of the defined optimal conditions. Finally, under optimal chromatographic conditions, the method was validated and applicability of the proposed method was confirmed.

  3. Ion-exchange chromatographic analysis of peroxynitric acid.

    Science.gov (United States)

    Nakashima, Yoichi; Ikawa, Satoshi; Tani, Atsushi; Kitano, Katsuhisa

    2016-01-29

    Ion-exchange chromatographic analysis of peroxynitric acid (O2NOOH) was performed by combining an acidic eluate with an UV-vis detector and immersing the separation column in an ice-water bath. The decomposition behavior of peroxynitric acid in the solution was also studied using this system. The fraction for the peroxynitric acid peak was collected. Ion-exchange chromatographic analysis of this fraction, after standing at room temperature for 24h, showed that the decomposition products were mainly nitrate ions with a very small amount of nitrous acid. The peroxynitric acid peak area correlated perfectly with the total amount of decomposition products. The ion-exchange chromatographic isolation allowed us to evaluate the molar extinction coefficient of peroxynitric acid precisely in a wider wavelength range than previous reports. The value decreases monotonically from 1729±26M(-1)cm(-1) at 200nm to 12.0±0.5M(-1)cm(-1) at 290nm.

  4. HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHIC DETERMINATION OF CAFFEIC ACID AND ROSMARINIC ACID FROM THE LEAVES OF Orthosiphon stamineus

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    M. Amzad Hossain

    2010-06-01

    Full Text Available This paper presents the studies performed on extraction of Orthosiphon stamineus, Benth by using different solvent for the identification and quantification of the caffeic acid derivatives such as caffeic acid  and rosmarinic acid which confers to the leaves of this plant with remarkable pharmaceutical properties. High performance thin-layer chromatographic (HPTLC allows the identification and the quantification of more than 20 samples in the same chromatographic run. The analysis of the samples requires 15-30 min compared with more than 2 h using a typical HPLC method. Using the techniques of the HPTLC and the UV-VIS spectra we have found that the extraction of this herb plant contain, the caffeic acid and rosmarinic acid ranging between 0.029% up to 0.506% and up to 0.24% to 2.24% respectively.     Keywords: Caffice acid derivatives, quantification, Malaysian Orthosiphon stamineus, HPTLC

  5. Thin-layer Chromatographic (TLC) Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

    OpenAIRE

    Kagan, Isabelle A.; Flythe, Michael D.

    2014-01-01

    A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth. The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken wit...

  6. A high performance thin layer chromatographic method for the estimation of colchicine in different formulations

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    Mohd Fahim

    2015-01-01

    Full Text Available Background: Colchicine is a main alkaloid present in bitter and sweet variety of colchicum (Colchicum luteum Baker, which have been reported to possess anti-rheumatic, anti-gout, and anticancer potential. Colchicum is an important ingredient of several Unani and Herbal formulations. Quantification of colchicine will play a great role in quality control of these formulations. Hence, a high-performance thin layer chromatographic (TLC method has been developed for the analysis of colchicine in Unani formulations of various dosage forms such as hubb (tablet and capsules. Materials and Methods: The samples were applied on aluminum TLC plates precoated with silica gel 60-F254and developed using mobile phase toluene-dichloromethane-methanol in equal proportions. Quantification was done by densitometric scanning at 350 nm, which showed a linear response in the range of 50–500 ng/spot. The developed method was validated as per the International Conference on Harmonization guidelines for linearity, precision, accuracy, specificity, robustness, limit of detection, and limit of quantification. Results and Conclusion: The developed method was applied for quantitative estimation of colchicine in different Unani and Herbal formulations. The method was found simple, selective, accurate with a wide range of linearity, hence suitable for the quality control of different formulations and varieties of colchicum with respect to colchicine content.

  7. Thin-layer chromatographic specification and separation of Cu(1+), Cu(2+), Ni(2+), and Co(2+) cations.

    Science.gov (United States)

    Savasci, Sahin; Akçay, Mehmet; Ergül, Soner

    2010-07-01

    The M(PyDTC)(2) (M: Cu, Co, or Ni) and CuPyDTC complexes, prepared by reactions of ammonium pyrrolidinedithiocarbamate with metal nitrates, are examined for qualitative analysis, speciation, and mutual separation using thin-layer chromatography systems. These complexes and their mixtures are spotted to the activated and non-activated thin layers of silica gel 60GF(254) (Si-60GF(254)) with a 250-microm thickness. Toluene-dichloromethane mixtures (4:1, 1:1, 1:4 v/v) are used as mobile phases for running of the complexes. All of these chromatographic systems are successfully used for speciation of Cu(2+) and Cu(1+) cations. The best analytical separation for the qualitative analysis of corresponding metal cations and mutual separation of components in M(PyDTC)(2) and CuPyDTC complexes are obtained when using pure toluene-dichloromethane (1:1 v/v) on the activated layer. This study shows that it is possible to qualitatively analyze and satisfactorily separate a mixture of Cu(1+), Cu(2+), Ni(2+), and Co(2+) cations on cited chromatographic systems. These results may be also said for the adaptability or validity on column chromatography.

  8. chromatographic analysis of crude oils and petroleum

    African Journals Online (AJOL)

    methods to industrial process operations have been discussed, ... petroleum by distillation, crystallization, and solvent extraction, as well as the analysis of the ...... Bland, F.W.; Davidson, R.L. Petroleum Processing Handbook, 4th ed., William ...

  9. Chromatographic methods for analysis of triazine herbicides.

    Science.gov (United States)

    Abbas, Hana Hassan; Elbashir, Abdalla A; Aboul-Enein, Hassan Y

    2015-01-01

    Gas chromatography (GC) and high-performance liquid chromatography (HPLC) coupled to different detectors, and in combination with different sample extraction methods, are most widely used for analysis of triazine herbicides in different environmental samples. Nowadays, many variations and modifications of extraction and sample preparation methods such as solid-phase microextraction (SPME), hollow fiber-liquid phase microextraction (HF-LPME), stir bar sportive extraction (SBSE), headspace-solid phase microextraction (HS-SPME), dispersive liquid-liquid microextraction (DLLME), dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO), ultrasound-assisted emulsification microextraction (USAEME), and others have been introduced and developed to obtain sensitive and accurate methods for the analysis of these hazardous compounds. In this review, several analytical properties such as linearity, sensitivity, repeatability, and accuracy for each developed method are discussed, and excellent results were obtained for the most of developed methods combined with GC and HPLC techniques for the analysis of triazine herbicides. This review gives an overview of recent publications of the application of GC and HPLC for analysis of triazine herbicides residues in various samples.

  10. GEL PERMEATION CHROMATOGRAPHIC ANALYSIS OF LACQUER POLYSACCHARIDE

    Institute of Scientific and Technical Information of China (English)

    QIU Xingping; ZHANG Lina; DU Yumin; QIAN Baogong; LU Zaimin

    1992-01-01

    Ten fractionated samples of Chinese lacquer polysaccharide in aqueous 0.1M NaCl solution were studied by aqueous-phase gel permeation chromatography (GPC). The universal calibration, broad MWD calibration and corrected column dispersion were adopted to the analysis of GPC chromatograms of the polysaccharide. The molecular weights Mw, Mn and polydispersity index Mw/Mn obtained from GPC are in good agreement with the results of light scattering and membrane osmometry. It is verified that the universal calibration concept is applicable to the lacquer polysaccharide having a number of side chains.

  11. Christhin: Quantitative Analysis of Thin Layer Chromatography

    CERN Document Server

    Barchiesi, Maximiliano; Renaudo, Carlos; Rossi, Pablo; Pramparo, María de Carmen; Nepote, Valeria; Grosso, Nelson Ruben; Gayol, María Fernanda

    2012-01-01

    Manual for Christhin 0.1.36 Christhin (Chromatography Riser Thin) is software developed for the quantitative analysis of data obtained from thin-layer chromatographic techniques (TLC). Once installed on your computer, the program is very easy to use, and provides data quickly and accurately. This manual describes the program, and reading should be enough to use it properly.

  12. Sampling flower scent for chromatographic analysis.

    Science.gov (United States)

    Stashenko, Elena E; Martínez, Jairo René

    2008-06-01

    The analysis of flower volatiles requires special methods for their isolation with enrichment. Living flowers show a continuous change in their volatile profile that depends on intrinsic (genetic) and external (light, temperature, hydric stress) factors. Excised flowers suffer rapid deterioration and loss of volatiles. While industrial isolation methods for flower volatiles are well established, those at the laboratory-scale experience progressive development, in the search for higher sensitivity, reproducibility, and simplicity. This review covers the flower scent sampling methods most commonly employed during the last decade, and includes comments on their strengths and limitations. The strengths of headspace solid-phase microextraction (HS-SPME) for in vivo monitoring are emphasized with the examples of monitoring the circadian variation of Brugmansia suaveolens flower scent and of volatile aldehyde detection in flower scent using on-fiber derivatization.

  13. Development of off-line layer chromatographic and total reflection X-ray fluorescence spectrometric methods for arsenic speciation

    Energy Technology Data Exchange (ETDEWEB)

    Mihucz, Victor G. [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); Moricz, Agnes M. [L. Eoetvoes University, Department of Chemical Technology and Environmental Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Kroepfl, Krisztina [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Szikora, Szilvia [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Tatar, Eniko [Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Parra, Lue Meru Marco [Universidad Centro-occidental Lisandro Alvarado, Decanato de Agronomia, Departamento de Quimica y Suelos Unidad de Analisis Instrumental, Apartado Postal 4076, Cabudare 3023 (Venezuela); Zaray, Gyula [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary) and Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary) and L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary)]. E-mail: zaray@ludens.elte.hu

    2006-11-15

    Rapid and low cost off-line thin layer chromatography-total reflection X-ray fluorescence spectrometry and overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods have been developed for separation of 25 ng of each As(III), As(V), monomethyl arsonic acid and dimethylarsinic acid applying a PEI cellulose stationary phase on plastic sheets and a mixture of acetone/acetic acid/water = 2:1:1 (v/v/v) as eluent system. The type of eluent systems, the amounts (25-1000 ng) of As species applied to PEI cellulose plates, injection volume, development distance, and flow rate (in case of overpressured thin layer chromatography) were taken into consideration for the development of the chromatographic separation. Moreover, a microdigestion method employing nitric acid for the As spots containing PEI cellulose scratched from the developed plates divided into segments was developed for the subsequent total reflection X-ray fluorescence spectrometry analysis. The method was applied for analysis of root extracts of cucumber plants grown in As(III) containing modified Hoagland nutrient solution. Both As(III) and As(V) were detected by applying the proposed thin layer chromatography/overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods.

  14. Chromatographic behaviour of alkaloids on thin layers of anion and cation exhangers. I. AG 1-X4 and cellex D.

    Science.gov (United States)

    Lepri, L; Desideri, P G; Lepori, M

    1976-01-07

    The chromatographic behaviour of 48 alkaloids has been studied on Bio-Rad AG 1-X4, Cellex D and microcrystalline cellulose, eluting with solutions of different pH but constant ionic strength (0.5). Many interesting separations were effected on both AG 1-X4 and Cellex D layers. The influence of pH on the chromatographic behaviour of alkaloids has been quantitatively studied and an equation was used that expresses the behaviour of the alkaloids on both AG 1-X4 (AcO-) and microcrystalling cellulose layers. The nonapplicability of this equation to Cellex D layers is discussed.

  15. Chromatographic separation of inorganic ions on thin layers of titanium phosphate ion-exchanger.

    Science.gov (United States)

    Ghoulipour, Vanik; Safari, Moharram

    2014-12-01

    The chromatographic behavior of 30 inorganic cations has been studied on thin layers of titanium phosphate ion-exchanger using several aqueous, organic and mixed mobile phases. The separation of one ion from several other ions and also ternary and binary separations have been developed. Some important analytical separations are reported. The effect of pH of the mobile phase on retention factor (Rf) values of the cations in the presence of complex-forming anion along with the separation power of the ion-exchanger were studied. This ion-exchanger exhibits high sorption capacity and varying selectivity towards metal ions and makes it a suitable stationaiy phase in thin layer chromatography.

  16. Chromatographic separation of inorganic ions on thin layers of titanium phosphate ion-exchanger

    Institute of Scientific and Technical Information of China (English)

    Vanik GHOULIPOUR; Moharram SAFARI

    2014-01-01

    The chromatographic behavior of 30 inorganic cations has been studied on thin layers of titanium phosphate ion-exchanger using several aqueous,organic and mixed mobile phases. The separation of one ion from several other ions and also ternary and binary separations have been developed. Some important analytical separations are reported. The effect of pH of the mobile phase on retention factor(Rf)values of the cations in the presence of complex-forming anion along with the separation power of the ion-exchanger were studied. This ion-exchanger exhibits high sorption capacity and varying selectivity towards metal ions and makes it a suitable stationary phase in thin layer chromatography.

  17. Preparation of porous hollow silica spheres via a layer-by-layer process and the chromatographic performance

    Science.gov (United States)

    Wei, Xiaobing; Gong, Cairong; Chen, Xujuan; Fan, Guoliang; Xu, Xinhua

    2017-03-01

    Hollow silica spheres possessing excellent mechanical properties were successfully prepared through a layer-by-layer process using uniform polystyrene (PS) latex fabricated by dispersion polymerization as template. The formation of hollow SiO2 micro-spheres, structures and properties were observed in detail by zeta potential, SEM, TEM, FTIR, TGA and nitrogen sorption porosimetry. The results indicated that the hollow spheres were uniform with particle diameter of 1.6 μm and shell thickness of 150 nm. The surface area was 511 m2/g and the pore diameter was 8.36 nm. A new stationary phase for HPLC was obtained by using C18-derivatized hollow SiO2 micro-spheres as packing materials and the chromatographic properties were evaluated for the separation of some regular small molecules. The packed column showed low column pressure, high values of efficiency (up to about 43 000 plates/m) and appropriate asymmetry factors.

  18. Chromatographic Methods for the Analysis of Polyphenols in Wines

    Directory of Open Access Journals (Sweden)

    Medić-Šarić, M.

    2009-03-01

    Full Text Available Wine is an excellent source of various classes of polyphenols, including phenolic acids, flavonoids, and trihydroxystilbene resveratrol (Fig.1. Polyphenols play a major role in wine quality since they contribute to the sensory characteristics of wine, particularly color and astringency. A recent interest in these substances has been stimulated by abundant evidence of their beneficial effects on human health, such as anticarcinogenic, antiinflamatory and antimicrobial activities. Therefore, numerous studies have been performed in the attempt to analyze polyphenols in wine. This paper reviews the current advances in the determination of polyphenols in wine by the major chromatographic techniques such as thin-layer chromatography (TLC and high-performance liquid chromatography (HPLC.The great complexity of the polyphenolic content of wine and the difficulty in obtaining some of the standards usually require sample preparation before analysis. Two methods for sample preparation, liquid-liquid extraction and solid-phase extraction, are most commonly applied. Hydrolysis is applied frequently, but not exclusively, to remove the sugar moieties from glycosides.TLC on silica gel plates is useful for the rapid and low-cost separation and identification of the polyphenols present in wine (Fig. 2. Densitometric quantitative analysis of polyphenols in wine extracts is usually performed by scanning the TLC plates with UV light at wavelengths of 350–365 nm or 250–260 nm (Fig. 3. For the evaluation of the most efficient mobile phase and an optimal choice of the combination of two or more mobile phases, two methods may be applied: information theory and numerical taxonomy. HPLC currently represents the most popular technique for the analysis of polyphenols in wine. For this purpose, a reversed-phase HPLC method that uses gradient elution with binary elution system is usually employed. Routine detection is based on measurement of UV-Vis absorption with a diode

  19. Extraction, chromatographic and mass spectrometric methods for lipid analysis.

    Science.gov (United States)

    Pati, Sumitra; Nie, Ben; Arnold, Robert D; Cummings, Brian S

    2016-05-01

    Lipids make up a diverse subset of biomolecules that are responsible for mediating a variety of structural and functional properties as well as modulating cellular functions such as trafficking, regulation of membrane proteins and subcellular compartmentalization. In particular, phospholipids are the main constituents of biological membranes and play major roles in cellular processes like transmembrane signaling and structural dynamics. The chemical and structural variety of lipids makes analysis using a single experimental approach quite challenging. Research in the field relies on the use of multiple techniques to detect and quantify components of cellular lipidomes as well as determine structural features and cellular organization. Understanding these features can allow researchers to elucidate the biochemical mechanisms by which lipid-lipid and/or lipid-protein interactions take place within the conditions of study. Herein, we provide an overview of essential methods for the examination of lipids, including extraction methods, chromatographic techniques and approaches for mass spectrometric analysis.

  20. High-Performance Thin-Layer Chromatographic Quantification of Rosmarinic Acid and Rutin in Abnormal Savda Munziq

    Directory of Open Access Journals (Sweden)

    S. G. Tian

    2013-01-01

    Full Text Available A high-performance thin-layer chromatographic (HPTLC method has been established for simultaneous analysis of rosmarinic acid and rutin in Abnormal Savda Munziq (ASMq. A methanol extract of ASMq was used for quantification. The compounds were separated on silica gel H thin layer plate with ethyl acetate-formic acid-acetic acid-water 15 : 1 : 1 : 1.5 (v/v as a developer, trichloroethanol as the color reagent. The plates were scanned at 365 nm. The linear calibration data of rosmarinic acid and rutin were in the range of 0.0508 to 0.2540 μg (r=0.9964, 0.2707 to 1.35354 μg (r=0.9981, respectively. The recovery rate of rosmarinic acid was 99.17% (RSD = 2.92% and rutin was 95.24% (RSD = 2.38%. The method enables rapid screening, precise, selective, and sensitive quantification for pharmaceutical analysis.

  1. Improved thin-layer chromatographic determination of phospholipids in gastric aspirate from newborns, for assessment of lung maturity.

    Science.gov (United States)

    Serrano de la Cruz, D; Santillana, E; Mingo, A; Fuenmayor, G; Pantoja, A; Fernández, E

    1988-04-01

    This one-dimensional thin-layer chromatographic method is used for assay of phospholipids in the gastric aspirate of newborns. The solvent mixture (chloroform/hexane/methanol/glacial acetic acid/water, 12/7/4/3/0.3 by vol) completely resolves lecithin, sphingomyelin, phosphatidylinositol, phosphatidylserine, phosphatidylethanolamine, and phosphatidylglycerol. The method is simple, precise, inexpensive, and rapid (chromatographic development takes less than 25 min) and gives high chromatographic resolution. We used this method to determine the lecithin/sphingomyelin densitometric ratio (L/S ratio) and the phosphatidylglycerol percentage in 200 samples of gastric aspirate and found an L/S ratio of 2.5 to be a satisfactory cutoff value for distinguishing fetal lung maturity and immaturity. We confirmed that the presence of phosphatidylglycerol excluded the possibility of respiratory distress.

  2. Thin-layer chromatographic (TLC) separations and bioassays of plant extracts to identify antimicrobial compounds.

    Science.gov (United States)

    Kagan, Isabelle A; Flythe, Michael D

    2014-03-27

    A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth. The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions. This paper describes standard protocols for TLC and contact bioautography with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light. Zones are cut out and incubated face down onto agar inoculated with the test microorganism. Inhibitory bands are visualized by staining the agar plates with tetrazolium red. The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen. The TLC methods apply to many types of plant extracts and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species.

  3. SIMULTANEOUS ESTIAMATION OF DROTAVERINE HCl AND NIMESULIDE IN PHARMACEUTICALS BY HIGH PERFORMANCE THIN LAYER CHROMATOGRAPHIC METHOD

    Directory of Open Access Journals (Sweden)

    Manoj S. Charde

    2012-05-01

    Full Text Available A simple, rapid, precise and accurate high-performance thin-layer chromatographic (HPTLC method was developed and validated for simultaneous determination of Drotaverine hydrochloride (DRO and Nimesulide (NIM in pharmaceutical preparations. Separation was achieved on a Merck HPTLC plates (0.2 mm thickness precoated with 60 F254 silica gel on aluminum sheet as the stationary phase using cyclohexane: methanol: ethyl acetate (5:2.:3v/v/v, as the mobile phase. Densitometric quantification was performed at l = 295 nm by reflectance scanning. The RF values of DRO and NIM were obtained 0.41 and 0.62 respectively. The linearity of proposed method was investigated in the range of 0.1 to 0.6 mg/spot and 0.2 to 0.7 mg/spot for DRO and NIM respectively.. The percentage recoveries for DRO and NIM were 99.91 % and 100.19 % by area and 99.63 % and 99.96 % by height, respectively. The developed method was suitably validated for precision, accuracy, specificity and ruggedness.

  4. Application of a stability-indicating thin-layer chromatographic method to the determination of tenatoprazole in pharmaceutical dosage forms.

    Science.gov (United States)

    Dhaneshwar, Sunil R; Bhusari, Vidhya K; Mahadik, Mahadeo V; Santakumari, B

    2009-01-01

    A sensitive, selective, precise, and stability-indicating thin-layer chromatographic (TLC) method was developed and validated for the determination of tenatoprazole both as a bulk drug and in formulation. The method uses TLC aluminum plates precoated with Silica Gel 60F-254 as the stationary phase and the solvent system toluene-ethyl acetate-methanol (6 + 4 + 1, v/v/v). This system gave compact spots for tenatoprazole (Rf value of 0.34 +/- 0.02). Tenatoprazole was subjected to acid and alkali hydrolysis, oxidation, and photodegradation. The peaks of the degradation products were well-resolved from that of the pure drug and had significantly different Rf values. Densitometric analysis of tenatoprazole was performed in the absorbance mode at 306 nm. The linear regression analysis data for the calibration plots showed a good linear relationship over the concentration range of 100-1500 ng/spot. The mean values of the correlation coefficient, slope, and intercept were 0.9989 +/- 1.42, 10.27 +/- 0.965, and 4894.2 +/- 1.24, respectively. The method was validated for precision, robustness, and recovery. The limit of detection and limit of quantitation were 50 and 100 ng/spot, respectively. Statistical analysis showed that the method is repeatable and selective for estimation of tenatoprazole. Because the method can separate the drug from its degradation products, it can be used to monitor stability.

  5. Chromatographic fingerprint similarity analysis for pollutant source identification.

    Science.gov (United States)

    Xie, Juan-Ping; Ni, Hong-Gang

    2015-12-01

    In the present study, a similarity analysis method was proposed to evaluate the source-sink relationships among environmental media for polybrominated diphenyl ethers (PBDEs), which were taken as the representative contaminants. Chromatographic fingerprint analysis has been widely used in the fields of natural products chemistry and forensic chemistry, but its application to environmental science has been limited. We established a library of various sources of media containing contaminants (e.g., plastics), recognizing that the establishment of a more comprehensive library allows for a better understanding of the sources of contamination. We then compared an environmental complex mixture (e.g., sediment, soil) with the profiles in the library. These comparisons could be used as the first step in source tracking. The cosine similarities between plastic and soil or sediment ranged from 0.53 to 0.68, suggesting that plastic in electronic waste is an important source of PBDEs in the environment, but it is not the only source. A similarity analysis between soil and sediment indicated that they have a source-sink relationship. Generally, the similarity analysis method can encompass more relevant information of complex mixtures in the environment than a profile-based approach that only focuses on target pollutants. There is an inherent advantage to creating a data matrix containing all peaks and their relative levels after matching the peaks based on retention times and peak areas. This data matrix can be used for source identification via a similarity analysis without quantitative or qualitative analysis of all chemicals in a sample.

  6. Development and validation of high-performance thin layer chromatographic method for ursolic acid in Malus domestica peel

    Directory of Open Access Journals (Sweden)

    P H Nikam

    2013-01-01

    Full Text Available Ursolic acid, a pentacyclic triterpenoid possess a wide range of pharmacological activities. It shows hypoglycemic, antiandrogenic, antibacterial, antiinflammatory, antioxidant, diuretic and cynogenic activity. It is commonly present in plants especially coating of leaves and fruits, such as apple fruit, vinca leaves, rosemary leaves, and eucalyptus leaves. A simple high-performance thin layer chromatographic method has been developed for the quantification of ursolic acid from apple peel (Malus domestica. The samples dissolved in methanol and linear ascending development was carried out in twin trough glass chamber. The mobile phase was selected as toluene:ethyl acetate:glacial acetic acid (70:30:2. The linear regression analysis data for the calibration plots showed good linear relationship with r 2 =0.9982 in the concentration range 0.2-7 ΅g/spot with respect to peak area. According to the ICH guidelines the method was validated for linearity, accuracy, precision, and robustness. Statistical analysis of the data showed that the method is reproducible and selective for the estimation of ursolic acid.

  7. Development and Validation of High-performance Thin Layer Chromatographic Method for Ursolic Acid in Malus domestica Peel.

    Science.gov (United States)

    Nikam, P H; Kareparamban, J A; Jadhav, A P; Kadam, V J

    2013-07-01

    Ursolic acid, a pentacyclic triterpenoid possess a wide range of pharmacological activities. It shows hypoglycemic, antiandrogenic, antibacterial, antiinflammatory, antioxidant, diuretic and cynogenic activity. It is commonly present in plants especially coating of leaves and fruits, such as apple fruit, vinca leaves, rosemary leaves, and eucalyptus leaves. A simple high-performance thin layer chromatographic method has been developed for the quantification of ursolic acid from apple peel (Malus domestica). The samples dissolved in methanol and linear ascending development was carried out in twin trough glass chamber. The mobile phase was selected as toluene:ethyl acetate:glacial acetic acid (70:30:2). The linear regression analysis data for the calibration plots showed good linear relationship with r(2)=0.9982 in the concentration range 0.2-7 μg/spot with respect to peak area. According to the ICH guidelines the method was validated for linearity, accuracy, precision, and robustness. Statistical analysis of the data showed that the method is reproducible and selective for the estimation of ursolic acid.

  8. Detection of arecoline by simple high-performance thin-layer chromatographic method in Indian nontobacco pan masala.

    Science.gov (United States)

    Adhikari, Anjan; Hazra, Alok Kumar; Sur, Tapas Kumar

    2015-01-01

    Chewing the habit of blended pan masala containing areca nut with or without tobacco is a common practice in the Indian subcontinent. Arecoline, a pyridine alkaloid presence in areca nut alarmed for oral carcinogenesis and strictly prohibited in the western world. However, in India using blended pan masala is very popular among young and old individuals. In this context, we aimed to detect arecoline in Indian blended nontobacco pan masala sold in Kolkata using a simple densitometric high-performance thin-layer chromatographic (HPTLC) method and for alarming their use in common people. Eleven popularly Indian blended nontobacco pan masala were collected from the territory of Kolkata and isolated arecoline, following solvent extraction method derived for pyridine alkaloid. The quantitative analysis of arecoline was measured using automated software-based HPTLC instruments and validated the method according to International Conference on Harmonization guidelines. Arecoline was detected in all 11 blended nontobacco pan masala samples in a range of minimum 130 to maximum 415 μg/g dry samples. Arecoline is hazardous carcinogenic compound, so the use of Indian blended nontobacco pan masala should be restricted. Further, the method was found suitable for routine quantitative analysis of arecoline in areca nut containing substances.

  9. Detection of arecoline by simple high-performance thin-layer chromatographic method in Indian nontobacco pan masala

    Directory of Open Access Journals (Sweden)

    Anjan Adhikari

    2015-01-01

    Full Text Available Chewing the habit of blended pan masala containing areca nut with or without tobacco is a common practice in the Indian subcontinent. Arecoline, a pyridine alkaloid presence in areca nut alarmed for oral carcinogenesis and strictly prohibited in the western world. However, in India using blended pan masala is very popular among young and old individuals. In this context, we aimed to detect arecoline in Indian blended nontobacco pan masala sold in Kolkata using a simple densitometric high-performance thin-layer chromatographic (HPTLC method and for alarming their use in common people. Eleven popularly Indian blended nontobacco pan masala were collected from the territory of Kolkata and isolated arecoline, following solvent extraction method derived for pyridine alkaloid. The quantitative analysis of arecoline was measured using automated software-based HPTLC instruments and validated the method according to International Conference on Harmonization guidelines. Arecoline was detected in all 11 blended nontobacco pan masala samples in a range of minimum 130 to maximum 415 μg/g dry samples. Arecoline is hazardous carcinogenic compound, so the use of Indian blended nontobacco pan masala should be restricted. Further, the method was found suitable for routine quantitative analysis of arecoline in areca nut containing substances.

  10. Authenticity analysis of pear juice employing chromatographic fingerprinting.

    Science.gov (United States)

    Willems, Jamie L; Low, Nicholas H

    2014-12-01

    Pear juice is predominately composed of carbohydrates/polyols (>95% of the total soluble solids), making it susceptible to adulteration by the addition of less expensive commercial sweeteners. In this research, the major carbohydrate and polyol (fructose, glucose, sucrose, and sorbitol) content of 32 pure pear juices representing five world producing regions and three years of production was determined. Additionally, methods employing oligosaccharide profiling to detect the debasing of these samples with four commercial sweeteners (HFCS 55 and 90, TIS, and HIS) were developed using capillary gas chromatography with flame ionization detection (CGC-FID) and high-performance liquid chromatography with pulsed amperometric detection (HPAE-PAD). Detection limits for the four commercial sweeteners ranged from 0.5 to 5.0% (v/v). In addition, the developed CGC-FID method could be used to (a) detect the addition of pear to apple juice via arbutin detection and (b) determine if a pear juice was produced using enzymatic liquefaction via the presence of O-β-d-glucopyranosyl-(1→4)-d-glucopyranose (cellobiose), all within a single chromatographic analysis.

  11. Comprehensive two-dimensional liquid chromatographic analysis of poloxamers.

    Science.gov (United States)

    Malik, Muhammad Imran; Lee, Sanghoon; Chang, Taihyun

    2016-04-15

    Poloxamers are low molar mass triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), having number of applications as non-ionic surfactants. Comprehensive one and two-dimensional liquid chromatographic (LC) analysis of these materials is proposed in this study. The separation of oligomers of both types (PEO and PPO) is demonstrated for several commercial poloxamers. This is accomplished at the critical conditions for one of the block while interaction for the other block. Reversed phase LC at CAP of PEO allowed for oligomeric separation of triblock copolymers with regard to PPO block whereas normal phase LC at CAP of PPO renders oligomeric separation with respect to PEO block. The oligomeric separation with regard to PEO and PPO are coupled online (comprehensive 2D-LC) to reveal two-dimensional contour plots by unconventional 2D IC×IC (interaction chromatography) coupling. The study provides chemical composition mapping of both PEO and PPO, equivalent to combined molar mass and chemical composition mapping for several commercial poloxamers.

  12. Ion Exchange and Thin Layer Chromatographic Separation and Identification of Amino Acids in a Mixture: An Experiment for General Chemistry and Biotechnology Laboratories

    Science.gov (United States)

    Brunauer, Linda S.; Caslavka, Katelyn E.; Van Groningen, Karinne

    2014-01-01

    A multiday laboratory exercise is described that is suitable for first-year undergraduate chemistry, biochemistry, or biotechnology students. Students gain experience in performing chromatographic separations of biomolecules, in both a column and thin layer chromatography (TLC) format. Students chromatographically separate amino acids (AA) in an…

  13. Ion Exchange and Thin Layer Chromatographic Separation and Identification of Amino Acids in a Mixture: An Experiment for General Chemistry and Biotechnology Laboratories

    Science.gov (United States)

    Brunauer, Linda S.; Caslavka, Katelyn E.; Van Groningen, Karinne

    2014-01-01

    A multiday laboratory exercise is described that is suitable for first-year undergraduate chemistry, biochemistry, or biotechnology students. Students gain experience in performing chromatographic separations of biomolecules, in both a column and thin layer chromatography (TLC) format. Students chromatographically separate amino acids (AA) in an…

  14. SIMULTANEOUS ESTIMATION AND VALIDATION OF VARDENAFIL AND DAPOXETINE HYDROCHLORIDE IN PHARMACEUTICAL FORMULATION BY THIN LAYER CHROMATOGRAPHIC DENSITOMETRIC METHOD

    OpenAIRE

    Bhavin Chapla; Gunjan Amin; Ashutosh Pandya; Jagdish Kakadiya; Nehal Shah

    2012-01-01

    The present manuscript describes new, simple, accurate, and precise high performance thin layer chromatography method for the simultaneous determination of Vardenafil and Dapoxetine in combined tablet dosage form. Chromatographic separation of the drugs was performed on aluminium plates pre coated with silica gel 60 F254 as the stationary phase and the solvent system consisted of Chloroform: Methanol: Acetonitrile: Formic acid (4: 0.8: 4: 1 v/v/v/v). Densitometric evaluation of the separated ...

  15. Development and validation of high-performance thin layer chromatographic method for ursolic acid in Malus domestica peel

    OpenAIRE

    P H Nikam; Kareparamban, J. A.; A P Jadhav; Kadam, V. J.

    2013-01-01

    Ursolic acid, a pentacyclic triterpenoid possess a wide range of pharmacological activities. It shows hypoglycemic, antiandrogenic, antibacterial, antiinflammatory, antioxidant, diuretic and cynogenic activity. It is commonly present in plants especially coating of leaves and fruits, such as apple fruit, vinca leaves, rosemary leaves, and eucalyptus leaves. A simple high-performance thin layer chromatographic method has been developed for the quantification of ursolic acid from apple peel (Ma...

  16. CHROMATOGRAPHIC METHODS IN THE ANALYSIS OF CHOLESTEROL AND RELATED LIPIDS

    NARCIS (Netherlands)

    HOVING, EB

    1995-01-01

    Methods using thin-layer chromatography, solid-phase extraction, gas chromatography, high-performance liquid chromatography and supercritical fluid chromatography are described for the analysis of single cholesterol, esterified and sulfated cholesterol, and for cholesterol in the context of other

  17. CHROMATOGRAPHIC METHODS IN THE ANALYSIS OF CHOLESTEROL AND RELATED LIPIDS

    NARCIS (Netherlands)

    HOVING, EB

    1995-01-01

    Methods using thin-layer chromatography, solid-phase extraction, gas chromatography, high-performance liquid chromatography and supercritical fluid chromatography are described for the analysis of single cholesterol, esterified and sulfated cholesterol, and for cholesterol in the context of other li

  18. Comparative tests to improve the gas chromatographic analysis of chlorobornanes in fish samples

    NARCIS (Netherlands)

    Boer, de J.; Leonards, P.E.G.; Klungsoyr, J.; McHugh, B.; Nixon, E.; McGovern, E.; Rimkus, G.G.

    2003-01-01

    A comparison was made between electron capture negative ionization quadrupole mass spectrometry (ECNI-MS) and electron capture detection (ECD) with regard to repeatability and reproducibility for the gas chromatographic (GC) analysis of toxaphene congeners [chlorobornanes (CHBs)]. The tests,

  19. Derivatization reactions in the gas—liquid chromatographic analysis of drugs in biological fluids

    NARCIS (Netherlands)

    Hulshoff, A.; Lingeman, H.

    1984-01-01

    Alkylation, acylation, silylation and other derivatization reactions applied to the gas chromatographic analysis of drugs in biological matrices are reviewed. Reaction conditions are discussed in relation to reaction mechanisms. Detector-oriented labelling of drugs, and derivatization with chiral re

  20. Chromatographic fingerprints analysis for evaluation of Ginkgo Biloba products

    Science.gov (United States)

    The leaf extract of Ginkgo biloba has purported value for improving mental capacities in Alzheimer’s patients. The flavonoids and the terpene lactones are considered to be the two main active components that influence human health. This paper compared an LC/UV chromatographic fingerprint method wi...

  1. Hydrocarbon Fuel Thermal Performance Modeling based on Systematic Measurement and Comprehensive Chromatographic Analysis

    Science.gov (United States)

    2016-07-31

    distribution unlimited Hydrocarbon Fuel Thermal Performance Modeling based on Systematic Measurement and Comprehensive Chromatographic Analysis Matthew...Technical Note 3. DATES COVERED (From - To) 04 January 2016 - 31 July 2016 4. TITLE AND SUBTITLE Hydrocarbon Fuel Thermal Performance Modeling based on...Systematic Measurement and Comprehensive Chromatographic Analysis 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

  2. Chromatographic and electrophoretic methods for nanodisc purification and analysis

    DEFF Research Database (Denmark)

    Justesen, Bo Højen; Günther-Pomorski, Thomas

    2014-01-01

    Soluble nanoscale lipid bilayers, termed nanodiscs, are widely used in science for studying the membrane-anchored and integral membrane protein complexes under defined experimental conditions. Although their formation occurs by a self-assembly process, nanodisc purification and the verification...... of proper reconstitution are still major challenges during the sample preparation. This review gives an overview of the methods used for purifying and analyzing nanodiscs and nanodisc-reconstituted membrane proteins, with an emphasis on the chromatographic and electrophoretic approaches....

  3. Acrylamide analysis in food by liquid chromatographic and gas chromatographic methods.

    Science.gov (United States)

    Elbashir, Abdalla A; Omar, Mei M Ali; Ibrahim, Wan Aini Wan; Schmitz, Oliver J; Aboul-Enein, Hassan Y

    2014-01-01

    Acrylamide (AA) is a compound classified as carcinogenic to humans by the International Agency for Research on Cancer. It was first discovered to be present in certain heated processed food by the Swedish National Food Administration (SNFA) and University of Stockholm in early 2002. The major pathway for AA formation in food is the Maillard reaction between reducing sugar and the amino acid asparagine at high temperature. Since the discovery of AA's presence in food, many analytical methods have been developed for determination of AA contents in different food matrices. Also, several studies have been conducted to develop extraction procedures for AA from difficult food matrices. AA is a small, highly polar molecule, which makes its extraction and analysis challenging. Many articles and reviews have been published dealing with AA in food. The aim of the review is to discuss AA formation in food, the factors affecting AA formation and removal, AA exposure assessment, AA extraction and cleanup from food samples, and analytical methods used in AA determination, such as high-performance liquid chromatography (HPLC) and gas chromatography (GC). Special attention is given to sample extraction and cleanup procedures and analytical techniques used for AA determination.

  4. Multivariate curve resolution based chromatographic peak alignment combined with parallel factor analysis to exploit second-order advantage in complex chromatographic measurements.

    Science.gov (United States)

    Parastar, Hadi; Akvan, Nadia

    2014-03-13

    In the present contribution, a new combination of multivariate curve resolution-correlation optimized warping (MCR-COW) with trilinear parallel factor analysis (PARAFAC) is developed to exploit second-order advantage in complex chromatographic measurements. In MCR-COW, the complexity of the chromatographic data is reduced by arranging the data in a column-wise augmented matrix, analyzing using MCR bilinear model and aligning the resolved elution profiles using COW in a component-wise manner. The aligned chromatographic data is then decomposed using trilinear model of PARAFAC in order to exploit pure chromatographic and spectroscopic information. The performance of this strategy is evaluated using simulated and real high-performance liquid chromatography-diode array detection (HPLC-DAD) datasets. The obtained results showed that the MCR-COW can efficiently correct elution time shifts of target compounds that are completely overlapped by coeluted interferences in complex chromatographic data. In addition, the PARAFAC analysis of aligned chromatographic data has the advantage of unique decomposition of overlapped chromatographic peaks to identify and quantify the target compounds in the presence of interferences. Finally, to confirm the reliability of the proposed strategy, the performance of the MCR-COW-PARAFAC is compared with the frequently used methods of PARAFAC, COW-PARAFAC, multivariate curve resolution-alternating least squares (MCR-ALS), and MCR-COW-MCR. In general, in most of the cases the MCR-COW-PARAFAC showed an improvement in terms of lack of fit (LOF), relative error (RE) and spectral correlation coefficients in comparison to the PARAFAC, COW-PARAFAC, MCR-ALS and MCR-COW-MCR results.

  5. [Sample preparation methods for chromatographic analysis of organic components in atmospheric particulate matter].

    Science.gov (United States)

    Hao, Liang; Wu, Dapeng; Guan, Yafeng

    2014-09-01

    The determination of organic composition in atmospheric particulate matter (PM) is of great importance in understanding how PM affects human health, environment, climate, and ecosystem. Organic components are also the scientific basis for emission source tracking, PM regulation and risk management. Therefore, the molecular characterization of the organic fraction of PM has become one of the priority research issues in the field of environmental analysis. Due to the extreme complexity of PM samples, chromatographic methods have been the chief selection. The common procedure for the analysis of organic components in PM includes several steps: sample collection on the fiber filters, sample preparation (transform the sample into a form suitable for chromatographic analysis), analysis by chromatographic methods. Among these steps, the sample preparation methods will largely determine the throughput and the data quality. Solvent extraction methods followed by sample pretreatment (e. g. pre-separation, derivatization, pre-concentration) have long been used for PM sample analysis, and thermal desorption methods have also mainly focused on the non-polar organic component analysis in PM. In this paper, the sample preparation methods prior to chromatographic analysis of organic components in PM are reviewed comprehensively, and the corresponding merits and limitations of each method are also briefly discussed.

  6. Validated binary high-performance thin-layer chromatographic fingerprints of polyphenolics for distinguishing different Salvia species.

    Science.gov (United States)

    Ciesla, Łukasz; Hajnos, Michał; Staszek, Dorota; Wojtal, Łukasz; Kowalska, Teresa; Waksmundzka-Hajnos, Monika

    2010-07-01

    Salvia (sage) is the largest plant genus in the family Lamiaceae, embracing ca. 900 species. There is a growing interest in investigating chemical contents of different Salvia species, as some of them have been reported to exhibit a wide spectrum of biological activity. In this paper, conjugated (i.e., binary) chromatographic fingerprints have been introduced for the twenty Salvia species that are grown and cultivated in Poland. Apart from videoscans traditionally used for a comparison of the high-performance thin-layer chromatography fingerprints, digital scanning profiles and images obtained with use of the image processing program have also been employed. It is the first time that binary chromatographic fingerprints are used for the investigation of chemical contents of the Salvia species. The proposed procedure is rapid when compared with the similar ones presented in the literature, and moreover, it is easy to handle. The proposed method offers a possibility to discern the investigated species. It can be applied not only for chemotaxonomic purposes but also for finding new plant species that can be used as medical herbs (as it has been proposed, with S. triloba having a similar profile to S. officinalis). Validation of the method reveals that it is specific, reproducible, precise, and robust.

  7. Size exclusion chromatographic analysis of polyphenol-serum albumin complexes.

    Science.gov (United States)

    Hatano, Tsutomu; Hori, Mami; Hemingway, Richard W; Yoshida, Takashi

    2003-08-01

    Formation of water-soluble polyphenol-protein complexes was investigated by size-exclusion chromatography (SEC). The combination of (-)-epigallocatechin gallate (EGCG) and bovine serum albumin (BSA), which did not form a precipitate after the solutions were mixed, showed an SEC peak due to complex formation 2-24 h after mixing. Peak size of the complex varied with time, suggesting slow change of the conformation of the protein accompanied by complexation. Formation of the complex was substantiated by ultrafiltration of the mixture; the complex did not pass through a membrane with a 100,000 nominal molecular weight limit (NMWL). The SEC profile varied with the combination of compounds. The peaks due to the complexes showed that the apparent value of the number average molecular weight (M(n)) of the EGCG-BSA complex was 2.8x10(5), while that of a pentagalloylglucose (PGG)-BSA complex was 9.5x10(5) under the conditions used. Dimeric hydrolyzable tannins, oenothein B and cornusiin A, also caused changes in the SEC profile of BSA, although the combinations did not show peaks attributable to formation of such large complexes observed for EGCG and PGG. Procyanidin B3 and (+)-catechin did not cause changes in the SEC profile of BSA. With cytochrome c, EGCG did not show any chromatographic changes.

  8. Liquid chromatographic analysis of oxytocin and its related substances.

    Science.gov (United States)

    Ashenafi, Dunge; Van Hemelrijck, Elise; Chopra, Shruti; Hoogmartens, Jos; Adams, Erwin

    2010-01-05

    A selective gradient liquid chromatographic (LC) method for the determination of oxytocin (OT) and its related substances in bulk drugs has been developed. The method uses a reversed-phase C18 column (25 cm x 4.0 mm i.d.), 5 microm kept at 40 degrees C. The mobile phases consist of acetonitrile, dihydrogen phosphate solution pH 4.4 and water. The flow rate is 1.0 ml/min. UV detection is performed at 220 nm. A system suitability test (SST) was developed to govern the quality of the separation. The separation towards OT components was investigated on different C18 columns. The developed method was further validated with respect to robustness, precision, sensitivity and linearity. A central composite design was applied to examine the robustness of the method. The method shows good precision, sensitivity, linearity and robustness. Two commercial OT samples were examined using this method. Furthermore, the method proved to be successful when applied to analyze a marketed OT formulation for injection.

  9. Validation of High-Performance Thin-Layer Chromatographic Methods for the Identification of Botanicals in a cGMP Environment

    Science.gov (United States)

    REICH, EIKE; SCHIBLI, ANNE; DEBATT, ALISON

    2009-01-01

    Current Good Manufacturing Practices (cGMP) for botanicals stipulates the use of appropriate methods for identification of raw materials. Due to natural variability, chemical analysis of plant material is a great challenge and requires special approaches. This paper presents a comprehensive proposal to the process of validating qualitative high-performance thin-layer chromatographic (HPTLC) methods, proving that such methods are suitable for the purpose. The steps of the validation process are discussed and illustrated with examples taken from a project aiming at validation of methods for identification of green tea leaf, ginseng root, eleuthero root, echinacea root, black cohosh rhizome, licorice root, kava root, milk thistle aerial parts, feverfew aerial parts, and ginger root. The appendix of the paper, which includes complete documentation and method write-up for those plants, is available on the J. AOAC Int. Website (http://www.atypon-link.com/AOAC/loi/jaoi). PMID:18376581

  10. Validation of high-performance thin-layer chromatographic methods for the identification of botanicals in a cGMP environment.

    Science.gov (United States)

    Reich, Eike; Schibli, Anne; DeBatt, Alison

    2008-01-01

    Current Good Manufacturing Practices (cGMP) for botanicals stipulates the use of appropriate methods for identification of raw materials. Due to natural variability, chemical analysis of plant material is a great challenge and requires special approaches. This paper presents a comprehensive proposal to the process of validating qualitative high-performance thin-layer chromatographic (HPTLC) methods, proving that such methods are suitable for the purpose. The steps of the validation process are discussed and illustrated with examples taken from a project aiming at validation of methods for identification of green tea leaf, ginseng root, eleuthero root, echinacea root, black cohosh rhizome, licorice root, kava root, milk thistle aerial parts, feverfew aerial parts, and ginger root. The appendix of the paper, which includes complete documentation and method write-up for those plants, is available on the J. AOAC Int. Website (http://www.atypon-link.com/AOAC/loi/jaoi).

  11. Chromatographic immunoassays: strategies and recent developments in the analysis of drugs and biological agents.

    Science.gov (United States)

    Matsuda, Ryan; Rodriguez, Elliott; Suresh, Doddavenkatanna; Hage, David S

    2015-01-01

    A chromatographic immunoassay is a technique in which an antibody or antibody-related agent is used as part of a chromatographic system for the isolation or measurement of a specific target. Various binding agents, detection methods, supports and assay formats have been developed for this group of methods, and applications have been reported that range from drugs, hormones and herbicides to peptides, proteins and bacteria. This review discusses the general principles and applications of chromatographic immunoassays, with an emphasis being given to methods and formats that have been developed for the analysis of drugs and biological agents. The relative advantages or limitations of each format are discussed. Recent developments and research in this field, as well as possible future directions, are also considered.

  12. [Use of LKhM-80 chromatograph in the analysis of urinary steroids].

    Science.gov (United States)

    Orlov, E N; Antipov, E M

    1995-01-01

    The paper describes a simple way of updating a Russian production-type LKaM-80 chromatograph in order to make a gas chromatographic analysis of urinary steroids for separation by using high performance capillary columns. To connect capillary columns, the units consisting of a gas heaving T-joint, a stream separating chamber, and a releasing restrictor were applied. To achieve satisfactory results, it is necessary to place a column through the tube connecting the union for attachment of the column and the flame-ionization detector so that the end of a capillary should be located at the detector as soon as closer. The updated chromatograph has been successfully used to obtain urinary steroidal profiles which are essential for the differential diagnosis of causes of hyperandrogyny in females, including pregnants.

  13. Solid Phase Extraction: Applications to the Chromatographic Analysis of Vegetable Oils and Fats

    Energy Technology Data Exchange (ETDEWEB)

    Panagiotopoulout, P. M.; Tsimidou, M.

    2002-07-01

    Applications of solid-phase extraction for the isolation of certain lipid classes prior to chromatographic analysis are given. More information was found for sterols and related compounds, polar phenols and contaminants such as polycyclic aromatic hydrocarbons. Detailed analytical protocols are presented and discussed in many cases. (Author) 120 refs.

  14. Analysis of variance of designed chromatographic data sets: The analysis of variance-target projection approach.

    Science.gov (United States)

    Marini, Federico; de Beer, Dalene; Joubert, Elizabeth; Walczak, Beata

    2015-07-31

    Direct application of popular approaches, e.g., Principal Component Analysis (PCA) or Partial Least Squares (PLS) to chromatographic data originating from a well-designed experimental study including more than one factor is not recommended. In the case of a well-designed experiment involving two or more factors (crossed or nested), data are usually decomposed into the contributions associated with the studied factors (and with their interactions), and the individual effect matrices are then analyzed using, e.g., PCA, as in the case of ASCA (analysis of variance combined with simultaneous component analysis). As an alternative to the ASCA method, we propose the application of PLS followed by target projection (TP), which allows a one-factor representation of the model for each column in the design dummy matrix. PLS application follows after proper deflation of the experimental matrix, i.e., to what are called the residuals under the reduced ANOVA model. The proposed approach (ANOVA-TP) is well suited for the study of designed chromatographic data of complex samples. It allows testing of statistical significance of the studied effects, 'biomarker' identification, and enables straightforward visualization and accurate estimation of between- and within-class variance. The proposed approach has been successfully applied to a case study aimed at evaluating the effect of pasteurization on the concentrations of various phenolic constituents of rooibos tea of different quality grades and its outcomes have been compared to those of ASCA.

  15. Chromatographic fingerprint analysis of yohimbe bark and related dietary supplements using UHPLC/UV/MS.

    Science.gov (United States)

    Sun, Jianghao; Chen, Pei

    2012-03-05

    A practical ultra high-performance liquid chromatography (UHPLC) method was developed for fingerprint analysis of and determination of yohimbine in yohimbe barks and related dietary supplements. Good separation was achieved using a Waters Acquity BEH C(18) column with gradient elution using 0.1% (v/v) aqueous ammonium hydroxide and 0.1% ammonium hydroxide in methanol as the mobile phases. The study is the first reported chromatographic method that separates corynanthine from yohimbine in yohimbe bark extract. The chromatographic fingerprint analysis was applied to the analysis of 18 yohimbe commercial dietary supplement samples. Quantitation of yohimbine, the traditional method for analysis of yohimbe barks, were also performed to evaluate the results of the fingerprint analysis. Wide variability was observed in fingerprints and yohimbine content among yohimbe dietary supplement samples. For most of the dietary supplements, the yohimbine content was not consistent with the label claims.

  16. A review of the extraction and chromatographic determination methods for the analysis of parabens.

    Science.gov (United States)

    Piao, Chunying; Chen, Ligang; Wang, Yu

    2014-10-15

    Parabens are a family of most widely used antimicrobial preservatives in food ingredients, cosmetic consumer products and pharmaceutical preparations. But several recent studies have cautioned that exposure to parabens may have more harmful consequences on animal and human health than what we realized previously, which made the analysis of parabens necessary. In this paper, we reviewed main sample preparation methods and chromatographic analysis methods proposed in formerly published works dealing with the analysis of parabens in different matrices. The sample preparation methods included ultrasonic assisted extraction, supercritical fluid extraction, pressurized liquid extraction, solid phase extraction, solid phase microextraction, liquid phase microextraction, dispersive liquid-liquid microextraction, stir bar sorptive extraction and matrix solid phase dispersion. The chromatographic analysis methods involved liquid chromatography, gas chromatography, and capillary electrophoresis. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Gas chromatographic analysis of polyhydroxybutyrate in activated sludge: a round-robin test.

    Science.gov (United States)

    Baetens, D; Aurola, A M; Foglia, A; Dionisi, D; van Loosdrecht, M C M

    2002-01-01

    Polyhydroxyalkanoates (PHA) and poly-beta-hydroxybutyrate (PHB) in particular have become compounds which is routinely investigated in wastewater research. The PHB analysis method has only recently been applied to activated sludge samples where PHA contents might be relatively low. This urges the need to investigate the reproducibility of the gas chromatographic method for PHB analysis. This was evaluated in a round-robin test in 5 European laboratories with samples from lab-scale and full-scale enhanced biological phosphorus removal systems. It was shown that the standard deviation of measurements in each lab and the reproducibility between the labs was very good. Experimental results obtained by different laboratories using this analysis method can be compared. Sludge samples with PHB contents varying between 0.3 and 22.5 mg PHB/mg sludge were analysed. The gas chromatographic method allows for PHV, PH2MB and PH2MV analysis as well.

  18. Simple automatic strategy for background drift correction in chromatographic data analysis.

    Science.gov (United States)

    Fu, Hai-Yan; Li, He-Dong; Yu, Yong-Jie; Wang, Bing; Lu, Peng; Cui, Hua-Peng; Liu, Ping-Ping; She, Yuan-Bin

    2016-06-01

    Chromatographic background drift correction, which influences peak detection and time shift alignment results, is a critical stage in chromatographic data analysis. In this study, an automatic background drift correction methodology was developed. Local minimum values in a chromatogram were initially detected and organized as a new baseline vector. Iterative optimization was then employed to recognize outliers, which belong to the chromatographic peaks, in this vector, and update the outliers in the baseline until convergence. The optimized baseline vector was finally expanded into the original chromatogram, and linear interpolation was employed to estimate background drift in the chromatogram. The principle underlying the proposed method was confirmed using a complex gas chromatographic dataset. Finally, the proposed approach was applied to eliminate background drift in liquid chromatography quadrupole time-of-flight samples used in the metabolic study of Escherichia coli samples. The proposed method was comparable with three classical techniques: morphological weighted penalized least squares, moving window minimum value strategy and background drift correction by orthogonal subspace projection. The proposed method allows almost automatic implementation of background drift correction, which is convenient for practical use.

  19. Chromatographic and Spectrophotometric Analysis of Phenolic Compounds from Fruits of Libidibia ferrea Martius.

    Science.gov (United States)

    Ferreira, Magda R A; Fernandes, Mônica T M; da Silva, Wliana A V; Bezerra, Isabelle C F; de Souza, Tatiane P; Pimentel, Maria F; Soares, Luiz A L

    2016-05-01

    Libidibia ferrea (Mart. ex Tul.) L.P. Queiroz (Fabaceae) is a tree which is native to Brazil, widely known as "Jucá," where its herbal derivatives are used in folk medicine with several therapeutic properties. The constituents, which have already been described in the fruit, are mainly hydrolysable tannins (gallic acid [GA] and ellagic acid [EA]). The aim of this study was to investigate the phenolic variability in the fruit of L. ferrea by ultraviolet/visible (UV/VIS) and chromatographic methods (high-performance liquid chromatography [HPLC]/high-performance thin layer chromatography [HPTLC]). Several samples were collected from different regions of Brazil and the qualitative (fingerprints by HPTLC and HPLC) and quantitative analysis (UV/VIS and HPLC) of polyphenols were performed. The HPTLC and HPLC profiles allowed separation and identification of both major analytical markers: EA and GA. The chemical profiles were similar in a number of spots or peaks for the samples, but some differences could be observed in the intensity or area of the analytical markers for HPTLC or HPLC, respectively. Regarding the quantitative analysis, the polyphenolic content by UV/VIS ranged from 13.99 to 37.86 g% expressed as GA or from 10.75 to 29.09 g% expressed as EA. The contents of EA and GA by liquid chromatography-reversed phase (LC-RP) method ranged from 0.57 to 2.68 g% and from 0.54 to 3.23 g%, respectively. The chemical profiles obtained by HPTLC or HPLC, as well as the quantitative analysis by spectrophotometry or LC-RP method, were suitable for discrimination of each herbal sample and can be used as tools for the comparative analysis of the fruits from L. ferrea. The polyphenols of fruits of Libidibia ferrea can be quantified by UV/VIS and HPLCThe HPLC method was able to detect the gallic and ellagic acids in several samples of fruits of Libidibia ferreaThe phenolic profiles of fruits from Libidibia ferrea by HPTLC and HPLC were reproductible. Abbreviations used: HPTLC

  20. Chromatographic finger print analysis of Naringi crenulata by HPTLC technique

    Institute of Scientific and Technical Information of China (English)

    Subramanian Sampathkumar; Ramakrishnan N

    2011-01-01

    Objective:To establish the fingerprint profile of Naringi crenulata (N. crenulata) (Roxb.) Nicols. using high performance thin layer chromatography (HPTLC) technique. Methods: Preliminary phytochemical screening was done and HPTLC studies were carried out. CAMAG HPTLC system equipped with Linomat V applicator, TLC scanner 3, Reprostar 3 and WIN CATS-4 software was used. Results: The results of preliminary phytochemical studies confirmed the presence of protein, lipid, carbohydrate, reducing sugar, phenol, tannin, flavonoid, saponin, triterpenoid, alkaloid, anthraquinone and quinone. HPTLC finger printing of ethanolic extract of stem revealed 10 spots with Rf values in the range of 0.08 to 0.65;bark showed 8 peaks with Rf values in the range of 0.07 to 0.63 and the ethanol extract of leaf revealed 8 peaks with Rf values in the range of 0.09 to 0.49, respectively. The purity of sample was confirmed by comparing the absorption spectra at start, middle and end position of the band. Conclusions:It can be concluded that HPTLC finger printing of N. crenulata may be useful in differentiating the species from the adulterant and act as a biochemical marker for this medicinally important plant in the pharmaceutical industry and plant systematic studies.

  1. Gas chromatographic technologies for the analysis of essential oils.

    Science.gov (United States)

    Marriot, P J; Shellie, R; Cornwell, C

    2001-11-30

    Essential oil analysis has basically had one technical goal: to achieve the best possible separation performance by using the most effective, available technology of the day. The result achieved from this may then be used to answer the research or industrial analysis questions which necessitated the analysis. This may be for comparative purposes, where one oil is contrasted with other(s) for quality control or investigation of adulteration, to discover new components, or to characterise the chemical classes of compounds present. Clearly, today the analyst turns to chromatography as the provider of separation and then may supplement that with mass spectrometry to aid identification. The power of GC-MS means that advances in both the separation technique, and improvements in mass spectrometry detection - along with improved data handling tools - will immediately be relevant to the essential oil area. This present review outlines the developmental nature of instrumental approaches to essential oil analysis using gas chromatography. Mass spectrometry will be included to the extent that it represents the hyphenation of choice for most analysts when analysing essential oils. Thus single-column and multi-dimensional analysis will be covered, as will sample handling or introduction techniques prior to the analysis step, where these techniques provide some measure of separation. The recent demonstration of comprehensive gas chromatography will be discussed as the potentially most powerful separation method for essential oils. This brief review is not intended to be a comprehensive dissertation on the field of essential oil analysis since that would require sufficient space to occupy a book in its own right. Rather, it will outline selected considerations and developments, to help explain where new technology has been applied to advantage in this field.

  2. Preprocessing and exploratory analysis of chromatographic profiles of plant extracts

    NARCIS (Netherlands)

    Hendriks, M.M.W.B.; Cruz-Juarez, L.; Bont, de D.; Hall, R.D.

    2005-01-01

    The characterization of herbal extracts to compare samples from different origin is important for robust production and quality control strategies. This characterization is now mainly performed by analysis of selected marker compounds. Metabolic fingerprinting of full metabolite profiles of plant ex

  3. High-performance liquid chromatographic column packings with different particle sizes: chromatographic behavior for the quality analysis of HuanglianShangqing pill.

    Science.gov (United States)

    Yang, Dongzhi; Li, Ying; Yang, Fangxiu; Du, Yan; Li, Yinjie; Zheng, Xiaoxiao; Tang, Daoquan

    2015-02-01

    The chromatographic separation of traditional Chinese medicines is still a highly challenging task in analytical science with respect to its hundreds and thousands of chemical compounds, while increase of separation efficiency can greatly improve the separation power of chromatographic column for traditional Chinese medicine. In this study, 13 bioactive components in HuanglianShangqing pill were selected as an index to optimize the separation conditions and evaluate the system suitability of three commercially available columns packed with 1.8, 3.5, and 5.0 μm particles. The chromatographic separations were obtained by the most appropriate Eclipse Plus C18 column (100 × 2.1 mm, 3.5 μm) within 45 min using gradient elution with aqueous-ammonium acetate (10 mmol/L, pH 5.0) and acetonitrile, at a flow rate of 0.3 mL/min and an operating temperature of 30°C. The quality of HuanglianShangqing pill was assessed through combining simultaneous quantification of 13 compounds with fingerprint analysis. For the qualitative analysis, mass spectrometry was used to confirm the 13 compounds. All the validation data conformed to the acceptable requirements. For the fingerprint analysis, 32 peaks were selected as the common peaks at 254 nm to evaluate the similarities among HuanglianShangqing pills obtained from ten manufacturers.

  4. Convective Interaction Media (CIM)--short layer monolithic chromatographic stationary phases.

    Science.gov (United States)

    Podgornik, Ales; Strancar, Ales

    2005-01-01

    Modern downstream processing requires fast and highly effective methods to obtain large quantities of highly pure substances. Commonly applied method for this purpose is chromatography. However, its main drawback is its throughput since purification, especially of large molecules, requires long process time. To overcome this problem several new stationary phases were introduced, among which short layer monoliths show superior properties for many applications. The purpose of this review is to give an overview about short methacrylate monolithic columns commercialised under the trademark Convective Interaction Media (CIM). Their unique properties are described from different perspectives, explaining reasons for their application on various areas. Approaches to prepare large volume methacrylate monolithic column are discussed and optimal solutions are given. Different examples of CIM monolithic column implementation are summarised in the last part of the article to give the reader an idea about their advantages.

  5. Stability indicating high performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in combined dosage form

    Institute of Scientific and Technical Information of China (English)

    Deepak Bageshwar; Vineeta Khanvilkar; Vilasrao Kadam

    2011-01-01

    A specific, precise and stability indicating high-performance thin-layer chromatographic method for simultaneous estimation of pantoprazole sodium and itopride hydrochloride in pharmaceutical formulations was developed and validated. The method employed TLC aluminium plates precoated with silica gel 60F254 as the stationary phase. The solvent system consisted of methanol:water:ammonium acetate; 4.0:1.0:0.5 (v/v/v). This system was found to give compact and dense spots for both itopride hydrochloride (Rf value of 0.55__+0.02) and pantoprazole sodium (Rf value of 0.85+0.04). Densitometric analysis of both drugs was carried out in the reflectance- absorbance mode at 289 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with R2=0.9988___0.0012 in the concentration range of 100--400 ng for pantoprazole sodium. Also, the linear regression analysis data for the calibration plots showed a good linear relationship with R2=0.9990_+0.0008 in the concentration range of 200-1200 ng for itopride hydrochloride. The method was validated for specificity, precision, robustness and recovery. Statistical analysis proves that the method is repeatable and selective for the estimation of both the said drugs. As the method could effectively separate the drug from its degradation products, it can be employed as a stability indicating method.

  6. Gas chromatographic analysis of synthetic glycidol esters, mono-, di- and triglycerides.

    Science.gov (United States)

    Engbersen, J A; van Stijn, F

    1976-03-01

    The gas chromatographic analysis of glycidol esters and mono-, di-,and triglycerides of palmitic-, stearic-, and oleic acid mixtures is described. The composition of the products was determined by gas chromatography on OV-17 after trimethylsilylation. Base-line separations between 1- and 2-monoglycerides and between 1,2- and 1,3-diglycerides were obtained. Isomerisation of the trimethylsilyl ethers of monoglycerides was not observed, contrary to published work.

  7. Differentiation of Bacillus anthracis from Bacillus cereus by gas chromatographic whole-cell fatty acid analysis.

    OpenAIRE

    Lawrence, D.; Heitefuss, S; Seifert, H S

    1991-01-01

    Three strains of Bacillus anthracis and seven strains of Bacillus cereus were grown on complex medium and on synthetic medium. Gas chromatographic analysis of whole-cell fatty acids of strains grown on complex medium gave nearly identical fatty acid patterns. Fatty acid patterns of strains grown on synthetic medium showed a high content of branched-chain fatty acids. Significant differences between the fatty acid patterns of the two species were found. Odd iso/anteiso fatty acid ratios were a...

  8. Optimization based on retention prediction and information theory for liquid-chromatographic analysis of alkylbenzenes

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Rieko; Hayashi Yuzuru; Suzuki Takashi; Saito Yukio (National Inst. of Hygienic Sciences, Tokyo (Japan)); Jinno Kiyokatsu (Toyohashi Univ. of Technology (Japan))

    1991-11-01

    The mobile phase composition and column length are optimized for analyses of six alkylbenzenes in reversed-phase liquid chromatography with the aid of retention prediction and information theory. Optimal conditions selected according to the resolution Rs and information theory are evaluated from the viewpoint of the precision and analytical efficiency (rapidity) of chromatography. The combination of the information-theoretical optimization with the retention prediction will accelerate the development in the automation of liquid-chromatographic analysis.

  9. The adaptive internet application for interpretation of the transformer oil gas chromatographic analysis results

    Directory of Open Access Journals (Sweden)

    Polužanski Vladimir

    2015-01-01

    Full Text Available This paper describes an adaptive Internet application for the interpretation of the transformer oil gas chromatographic analysis results. The first version of the application is developed by following an evolutionary software development concept. The most important software development risks and the appropriate solutions are described. An open-source web framework named Bootstrap is used for an application implementation. The application is developed by using ASP.NET and MS SQL server.

  10. SIMULTANEOUS ESTIMATION AND VALIDATION OF VARDENAFIL AND DAPOXETINE HYDROCHLORIDE IN PHARMACEUTICAL FORMULATION BY THIN LAYER CHROMATOGRAPHIC DENSITOMETRIC METHOD

    Directory of Open Access Journals (Sweden)

    Bhavin Chapla

    2012-05-01

    Full Text Available The present manuscript describes new, simple, accurate, and precise high performance thin layer chromatography method for the simultaneous determination of Vardenafil and Dapoxetine in combined tablet dosage form. Chromatographic separation of the drugs was performed on aluminium plates pre coated with silica gel 60 F254 as the stationary phase and the solvent system consisted of Chloroform: Methanol: Acetonitrile: Formic acid (4: 0.8: 4: 1 v/v/v/v. Densitometric evaluation of the separated zones was performed at 232 nm. The two drugs were satisfactorily resolved with Rf values 0.47 and 0.79 for Vardenafil and Dapoxetine Hydrochloride, respectively. The linear regression data for the calibration plots showed good relationship with r2 = 0.9995 from 150-750 ng/spot for Vardenafil and r2 = 0.9980 from 450-2250 ng/spot for Dapoxetine Hydrochloride. The methods were validated for precision, accuracy, and recovery. The percentage recovery for Vardenafil was found to be 99.58 – 100.72 % and 99.97 – 100.21% for Dapoxetine Hydrochloride. The limits of detection and quantification were 21.86 and 66.25 ng/spot per spot for Vardenafil and 128.58. and 389.64 ng/spot per spot for Dapoxetine Hydrochloride, respectively.

  11. Revisiting Greek Propolis: Chromatographic Analysis and Antioxidant Activity Study

    Science.gov (United States)

    Kasiotis, Konstantinos M.; Anastasiadou, Pelagia; Papadopoulos, Antonis; Machera, Kyriaki

    2017-01-01

    Propolis is a bee product that has been extensively used in alternative medicine and recently has gained interest on a global scale as an essential ingredient of healthy foods and cosmetics. Propolis is also considered to improve human health and to prevent diseases such as inflammation, heart disease, diabetes and even cancer. However, the claimed effects are anticipated to be correlated to its chemical composition. Since propolis is a natural product, its composition is consequently expected to be variable depending on the local flora alignment. In this work, we present the development of a novel HPLC-PDA-ESI/MS targeted method, used to identify and quantify 59 phenolic compounds in Greek propolis hydroalcoholic extracts. Amongst them, nine phenolic compounds are herein reported for the first time in Greek propolis. Alongside GC-MS complementary analysis was employed, unveiling eight additional newly reported compounds. The antioxidant activity study of the propolis samples verified the potential of these extracts to effectively scavenge radicals, with the extract of Imathia region exhibiting comparable antioxidant activity to that of quercetin. PMID:28103258

  12. Comprehensive Quantitative Analysis of SQ Injection Using Multiple Chromatographic Technologies.

    Science.gov (United States)

    Chau, Siu-Leung; Huang, Zhi-Bing; Song, Yan-Gang; Yue, Rui-Qi; Ho, Alan; Lin, Chao-Zhan; Huang, Wen-Hua; Han, Quan-Bin

    2016-08-19

    Quality control of Chinese medicine injections remains a challenge due to our poor knowledge of their complex chemical profile. This study aims to investigate the chemical composition of one of the best-selling injections, Shenqi Fuzheng (SQ) injection (SQI), via a full component quantitative analysis. A total of 15 representative small molecular components of SQI were simultaneously determined using ultra-high performance liquid chromatography (UHPLC) coupled with quadrupole tandem time-of-flight mass spectrometry (Q-TOF-MS); saccharide composition of SQI was also quantitatively determined by high performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD) on an amino column before and after acid hydrolysis. The existence of polysaccharides was also examined on a gel permeation chromatography column. The method was well validated in terms of linearity, sensitivity, precision, accuracy and stability, and was successfully applied to analyze 13 SQI samples. The results demonstrate that up to 94.69% (w/w) of this injection product are quantitatively determined, in which small molecules and monosaccharide/sucrose account for 0.18%-0.21%, and 53.49%-58.2%, respectively. The quantitative information contributes to accumulating scientific evidence to better understand the therapy efficacy and safety of complex Chinese medicine injections.

  13. Revisiting Greek Propolis: Chromatographic Analysis and Antioxidant Activity Study.

    Science.gov (United States)

    Kasiotis, Konstantinos M; Anastasiadou, Pelagia; Papadopoulos, Antonis; Machera, Kyriaki

    2017-01-01

    Propolis is a bee product that has been extensively used in alternative medicine and recently has gained interest on a global scale as an essential ingredient of healthy foods and cosmetics. Propolis is also considered to improve human health and to prevent diseases such as inflammation, heart disease, diabetes and even cancer. However, the claimed effects are anticipated to be correlated to its chemical composition. Since propolis is a natural product, its composition is consequently expected to be variable depending on the local flora alignment. In this work, we present the development of a novel HPLC-PDA-ESI/MS targeted method, used to identify and quantify 59 phenolic compounds in Greek propolis hydroalcoholic extracts. Amongst them, nine phenolic compounds are herein reported for the first time in Greek propolis. Alongside GC-MS complementary analysis was employed, unveiling eight additional newly reported compounds. The antioxidant activity study of the propolis samples verified the potential of these extracts to effectively scavenge radicals, with the extract of Imathia region exhibiting comparable antioxidant activity to that of quercetin.

  14. Comprehensive Quantitative Analysis of SQ Injection Using Multiple Chromatographic Technologies

    Directory of Open Access Journals (Sweden)

    Siu-Leung Chau

    2016-08-01

    Full Text Available Quality control of Chinese medicine injections remains a challenge due to our poor knowledge of their complex chemical profile. This study aims to investigate the chemical composition of one of the best-selling injections, Shenqi Fuzheng (SQ injection (SQI, via a full component quantitative analysis. A total of 15 representative small molecular components of SQI were simultaneously determined using ultra-high performance liquid chromatography (UHPLC coupled with quadrupole tandem time-of-flight mass spectrometry (Q-TOF-MS; saccharide composition of SQI was also quantitatively determined by high performance liquid chromatography (HPLC with evaporative light scattering detector (ELSD on an amino column before and after acid hydrolysis. The existence of polysaccharides was also examined on a gel permeation chromatography column. The method was well validated in terms of linearity, sensitivity, precision, accuracy and stability, and was successfully applied to analyze 13 SQI samples. The results demonstrate that up to 94.69% (w/w of this injection product are quantitatively determined, in which small molecules and monosaccharide/sucrose account for 0.18%–0.21%, and 53.49%–58.2%, respectively. The quantitative information contributes to accumulating scientific evidence to better understand the therapy efficacy and safety of complex Chinese medicine injections.

  15. A novel thermodynamic state recursion method for description of nonideal nonlinear chromatographic process of frontal analysis.

    Science.gov (United States)

    Liu, Qian; OuYang, Liangfei; Liang, Heng; Li, Nan; Geng, Xindu

    2012-06-01

    A novel thermodynamic state recursion (TSR) method, which is based on nonequilibrium thermodynamic path described by the Lagrangian-Eulerian representation, is presented to simulate the whole chromatographic process of frontal analysis using the spatial distribution of solute bands in time series like as a series of images. TSR differs from the current numerical methods using the partial differential equations in Eulerian representation. The novel method is used to simulate the nonideal, nonlinear hydrophobic interaction chromatography (HIC) processes of lysozyme and myoglobin under the discrete complex boundary conditions. The results show that the simulated breakthrough curves agree well with the experimental ones. The apparent diffusion coefficient and the Langmuir isotherm parameters of the two proteins in HIC are obtained by the state recursion inverse method. Due to its the time domain and Markov characteristics, TSR is applicable to the design and online control of the nonlinear multicolumn chromatographic systems.

  16. Analysis of turbulent boundary layers

    CERN Document Server

    Cebeci, Tuncer

    1974-01-01

    Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculati

  17. Nanoelectromechanical resonator arrays for ultrafast, gas-phase chromatographic chemical analysis.

    Science.gov (United States)

    Li, Mo; Myers, E B; Tang, H X; Aldridge, S J; McCaig, H C; Whiting, J J; Simonson, R J; Lewis, N S; Roukes, M L

    2010-10-13

    Miniaturized gas chromatography (GC) systems can provide fast, quantitative analysis of chemical vapors in an ultrasmall package. We describe a chemical sensor technology based on resonant nanoelectromechanical systems (NEMS) mass detectors that provides the speed, sensitivity, specificity, and size required by the microscale GC paradigm. Such NEMS sensors have demonstrated detection of subparts per billion (ppb) concentrations of a phosphonate analyte. By combining two channels of NEMS detection with an ultrafast GC front-end, chromatographic analysis of 13 chemicals was performed within a 5 s time window.

  18. Chromatographic background drift correction coupled with parallel factor analysis to resolve coelution problems in three-dimensional chromatographic data: quantification of eleven antibiotics in tap water samples by high-performance liquid chromatography coupled with a diode array detector.

    Science.gov (United States)

    Yu, Yong-Jie; Wu, Hai-Long; Fu, Hai-Yan; Zhao, Juan; Li, Yuan-Na; Li, Shu-Fang; Kang, Chao; Yu, Ru-Qin

    2013-08-01

    Chromatographic background drift correction has been an important field of research in chromatographic analysis. In the present work, orthogonal spectral space projection for background drift correction of three-dimensional chromatographic data was described in detail and combined with parallel factor analysis (PARAFAC) to resolve overlapped chromatographic peaks and obtain the second-order advantage. This strategy was verified by simulated chromatographic data and afforded significant improvement in quantitative results. Finally, this strategy was successfully utilized to quantify eleven antibiotics in tap water samples. Compared with the traditional methodology of introducing excessive factors for the PARAFAC model to eliminate the effect of background drift, clear improvement in the quantitative performance of PARAFAC was observed after background drift correction by orthogonal spectral space projection.

  19. Isolation and gas chromatographic analysis of lupenone and lupeol from sorbus cortex

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.M. [Chungnam National University, Taejon (Korea, Republic of); Lee, C.G. [Chongju University, Congju (Korea, Republic of)

    1999-04-01

    Lupenone and lupeol, the triterpenoids of sorbus cortex, were isolated with silica gel column chromatography and used as the standard substances for the quantitative analysis. The compounds were identified with IR, NMR, EI-MS. They were separated on VA-5MS [(5%-phenyl)methlypolysiloxane, 30m*0.25mm, 0.25 {mu}m] column by gas-chromatograph. The contents of lupeone and lupeol in three different samples of Sorbus Cortex were in the range of 0.050{approx}0.056% and 0.772{approx}0.834%, respectively. 15 refs., 6 figs., 2 tabs.

  20. Multivariate analysis of chromatographic retention data as a supplementary means for grouping structurally related compounds.

    Science.gov (United States)

    Fasoula, S; Zisi, Ch; Sampsonidis, I; Virgiliou, Ch; Theodoridis, G; Gika, H; Nikitas, P; Pappa-Louisi, A

    2015-03-27

    In the present study a series of 45 metabolite standards belonging to four chemically similar metabolite classes (sugars, amino acids, nucleosides and nucleobases, and amines) was subjected to LC analysis on three HILIC columns under 21 different gradient conditions with the aim to explore whether the retention properties of these analytes are determined from the chemical group they belong. Two multivariate techniques, principal component analysis (PCA) and discriminant analysis (DA), were used for statistical evaluation of the chromatographic data and extraction similarities between chemically related compounds. The total variance explained by the first two principal components of PCA was found to be about 98%, whereas both statistical analyses indicated that all analytes are successfully grouped in four clusters of chemical structure based on the retention obtained in four or at least three chromatographic runs, which, however should be performed on two different HILIC columns. Moreover, leave-one-out cross-validation of the above retention data set showed that the chemical group in which an analyte belongs can be 95.6% correctly predicted when the analyte is subjected to LC analysis under the same four or three experimental conditions as the all set of analytes was run beforehand. That, in turn, may assist with disambiguation of analyte identification in complex biological extracts.

  1. [Multi-component quantitative analysis combined with chromatographic fingerprint for quality assessment of Onosma hookeri].

    Science.gov (United States)

    Aga, Er-bu; Nie, Li-juan; Dongzhi, Zhuo-ma; Wang, Ju-le

    2015-11-01

    A method for simultaneous determination of the shikonin, acetyl shikonin and β, β'-dimethylpropene shikonin in Onosma hookeri and the chromatographic fingerprint was estabished by HPLC-DAD on an Agilent Zorbax SB-column with a gradient elution of acetonitrile and water at 0.8 mL x min(-1), 30 degrees C. The quality assessment was conducted by comparing the content difference of three naphthoquinone constituents, in combination with chromatographic fingerprint analysis and systems cluster analysis among 7 batches of radix O. hookeri. The content of the three naphthoquinone constituents showed wide variations in 7 bathces. The similarity value of the fingerprints of sample 5, 6 and 7 was above 0.99, sample 2 and 3 above 0.97, sample 3 and 4 above 0.90, and other samples larger than 0.8, which was in concert with the content of three naphthoquinone constituents. The 7 samples were roughly divided into 4 categories. The results above indicated that the using of this medicine is complex and rather spotty. The established HPLC fingerprints and the quantitative analysis method can be used efficiently for quality assessment of O. hookeri.

  2. Multivariate analysis of variance of designed chromatographic data. A case study involving fermentation of rooibos tea.

    Science.gov (United States)

    Marini, Federico; de Beer, Dalene; Walters, Nico A; de Villiers, André; Joubert, Elizabeth; Walczak, Beata

    2017-03-17

    An ultimate goal of investigations of rooibos plant material subjected to different stages of fermentation is to identify the chemical changes taking place in the phenolic composition, using an untargeted approach and chromatographic fingerprints. Realization of this goal requires, among others, identification of the main components of the plant material involved in chemical reactions during the fermentation process. Quantitative chromatographic data for the compounds for extracts of green, semi-fermented and fermented rooibos form the basis of preliminary study following a targeted approach. The aim is to estimate whether treatment has a significant effect based on all quantified compounds and to identify the compounds, which contribute significantly to it. Analysis of variance is performed using modern multivariate methods such as ANOVA-Simultaneous Component Analysis, ANOVA - Target Projection and regularized MANOVA. This study is the first one in which all three approaches are compared and evaluated. For the data studied, all tree methods reveal the same significance of the fermentation effect on the extract compositions, but they lead to its different interpretation.

  3. REVERSE PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD FOR THE ANALYSIS OF GLIPIZIDE IN PHARMACEUTICAL DOSAGE FORMS

    Directory of Open Access Journals (Sweden)

    Sheikh Rahila

    2010-12-01

    Full Text Available A rapid and sensitive reverse phase high performance liquid chromatographic methods depicted for the qualitative and quantitative assay of glipizide in pharmaceutical dosage forms. Glipizide was chromatographed on reverse phase C18 column with mobile phase consisting of 0.05 M Potassium Dihydrogen Orthophosphate: Methanol [15: 85 %v/v, pH 7.0 ± 0.05, adjusted with 1% Triethylamine]. The mobile phase was pumped at a flow rate 1 mL/min. Quantification was achieved by monitoring the ultraviolet absorbance at 225 ηm. The average retention time for Glipizide was found to be 3.21 ± 0.07. With this method, linearity was observed in the range of 10 – 2000 ηg/ml. The LOD and LOQ were found to be 5 ηg/ml and 15 ηg/ml respectively. The method was applicable for the analysis of drug in tablet formulation. The results of analysis were validated statistically.

  4. Fingerprinting of morphine using chromatographic purity profiling and multivariate data analysis.

    Science.gov (United States)

    Acevska, Jelena; Stefkov, Gjoshe; Cvetkovikj, Ivana; Petkovska, Rumenka; Kulevanova, Svetlana; Cho, JungHwan; Dimitrovska, Aneta

    2015-05-10

    Chromatographic purity profiling (CPP) is the common name of a group of analytical and chemometric applications for detection, identification and quantitative determination of related substances and other impurities in active pharmaceutical ingredients (APIs) and finished dosage forms (FDFs). CPP is used for fingerprinting and discriminating between samples, thus representing a core activity in modern drug analysis. The worldwide demand for morphine and its congeners is tremendous and depends entirely on the supply of natural opiates. The aim of this research was to develop a methodology that enables identification of a source of morphine, thus revealing falsification of the substance. The characteristic and reproducible features of impurity profiles for 28 samples of morphine (6 morphine sulfate, 9 morphine hydrochloride and 13 morphine base) were captured by a new LC/MS method for impurity profiling of morphine. The impurity profile encompasses the related substances specified in relevant Ph.Eur. monographs, as well as the other morphinane like impurities, including the naturally occurring co-extracted alkaloids. Different pattern recognition techniques (unsupervised and supervised) were used to reveal the differentiation features of the morphine fingerprints for classification and authentication purposes. The results described in this research open the possibility of using the chromatographic purity profile combined with multivariate data analysis for fingerprinting of morphine samples.

  5. Computerised gas chromatographic-mass spectrometric analysis of complex mixtures of alkyl porphyrins.

    Science.gov (United States)

    Marriott, P J; Gill, J P; Evershed, R P; Hein, C S; Eglinton, G

    1984-01-01

    Computerised capillary gas chromatography-mass spectrometry (GC-MS) analysis of complex mixtures of alkyl porphyrins, as their bis-(trimethylsiloxy)silicon(IV) and bis(tert.-butyldimethylsiloxy)silicon(IV) derivatives, is described. The latter derivative is more suitable for routine GC-MS analysis. This computerised GC-MS approach, when applied to the alkyl porphyrins of two geological samples, a bitumen (Gilsonite, Eocene age, UT, U.S.A.) and a crude oil (Boscan, Cretaceous age, West Venezuela), has revealed the highly complex compositions of these fractions. Computer-aided data processing, using relative retention index (RRI) calculations, facilitated the classification of the chromatographic peaks according to structural type and membership of pseudo-homologous series. Computerised GC-MS is compared with, and contrasted to high-performance liquid chromatography as a means of petroporphyrin analysis.

  6. Validated stability-indicating high performance thin layer chromatographic method for determination of Ivabradine hydrochloride in bulk and marketed formulation: An application to kinetic study

    Directory of Open Access Journals (Sweden)

    Mitesh H. Motisariya

    2013-12-01

    Full Text Available A sensitive, selective, precise and accurate stability-indicating high-performance thin layer chromatographic method for analysis of Ivabradine hydrochloride (IH an anti anginal agent, both as a bulk drug and in formulations was developed and validated according to ICH guideline. Densitometric analysis of IH was carried out in the absorbance mode at 287 nm using ethyl acetate: 0.389 M ammonium acetate in methanol (1:5, v/v as solvent system. This system was found to give compact spots for IH at an Rf value of 0.36 ± 0.01. Moreover, IH was subjected to acid and alkali hydrolysis, oxidation, accelerated humidity/temperature, wet heat treatment, and photo degradation. The drug undergoes degradation under mainly acidic and basic conditions. Also the degraded products were well resolved from the pure drug with significantly different Rf values. Linearity was found to be in the range of 1200–2800 ng/band. The LOD and LOQ for IH were 255.86 ng/band and 775.33 ng/band, respectively. “Bartlett’s test” and “Lack of fit” applied on peak area for linearity, additionally proved validity of the developed method. Good accuracy and precision were obtained as revealed from %RSD value less than 2. Similarly, no interference was observed from common excipients in tablet formulation as well as degradation product, indicating specificity of the method. As the method could effectively separate the drug from its degradation product, it can be employed as a stability-indicating one. Moreover, proposed method was also utilized to investigate the kinetics of acidic degradation process at different temperatures and first order rate constant, half-life, shelf-life and activation energy were calculated.

  7. Development and validation of a reversed phase liquid chromatographic method for analysis of griseofulvin and impurities.

    Science.gov (United States)

    Kahsay, Getu; Adegoke, Aremu Olajire; Van Schepdael, Ann; Adams, Erwin

    2013-06-01

    A simple and robust reversed phase liquid chromatographic method was developed and validated for the quantitative determination of griseofulvin (GF) and its impurities in drug substances and drug products (tablets). Chromatographic separation was achieved on a Discovery C18 (250mm×4.6mm, 5μm) column kept at 30°C. The mobile phase consisted of a gradient mixture of mobile phase A (water-0.1% formic acid pH 4.5, 80:20, v/v) and B (ACN-water-0.1% formic acid pH 4.5, 65:15:20, v/v/v) pumped at a flow rate of 1.0mL/min. UV detection was performed at 290nm. The method was validated for its robustness, sensitivity, precision, accuracy and linearity based on ICH guidelines. The robustness study was performed by means of an experimental design and multivariate analysis. Satisfactory results were obtained from the validation studies. The use of volatile mobile phases allowed for the identification of three main impurities present above the identification threshold using mass spectrometry (MS). The developed LC method has been applied for the assay and impurity determination of GF drug substances and tablets. The method could be very useful for the quality control of GF and its impurities in bulk and formulated dosage forms.

  8. Validated high-performance thin-layer chromatographic (HPTLC method for simultaneous determination of nadifloxacin, mometasone furoate, and miconazole nitrate cream using fractional factorial design

    Directory of Open Access Journals (Sweden)

    Kalpana G. Patel

    2016-07-01

    Full Text Available A high-performance thin-layer chromatographic method for simultaneous determination of nadifloxacin, mometasone furoate, and miconazole nitrate was developed and validated as per International Conference on Harmonization guidelines. High-performance thin-layer chromatographic separation was performed on aluminum plates precoated with silica gel 60F254 and methanol:ethyl acetate:toluene: acetonitrile:3M ammonium formate in water (1:2.5:6.0:0.3:0.2, % v/v as optimized mobile phase at detection wavelength of 224 nm. The retardation factor (Rf values for nadifloxacin, mometasone furoate, and miconazole nitrate were 0.23, 0.70, and 0.59, respectively. Percent recoveries in terms of accuracy for the marketed formulation were found to be 98.35–99.76%, 99.36–99.65%, and 99.16–100.25% for nadifloxacin, mometasone furoate, and miconazole nitrate, respectively. The pooled percent relative standard deviation for repeatability and intermediate precision studies was found to be < 2% for three target analytes. The effect of four independent variables, methanol content in total mobile phase, wavelength, chamber saturation time, and solvent front, was evaluated by fractional factorial design for robustness testing. Amongst all four factors, volume of methanol in mobile phase appeared to have a possibly significant effect on retention factor of miconazole nitrate compared with the other two drugs nadifloxacin and mometasone furoate, and therefore it was important to be carefully controlled. In summary, a novel, simple, accurate, reproducible, and robust high-performance thin-layer chromatographic method was developed, which would be of use in quality control of these cream formulations.

  9. Gas chromatographic analysis of methyl formate and application in methanol poisoning cases

    Energy Technology Data Exchange (ETDEWEB)

    Fraser, A.D.; MacNeil, W. (Dalhousie Univ., Halifax, Nova Scotia (Canada))

    A modified headspace gas chromatographic method for analysis of formate in biological fluids is described. Serum or whole blood specimens were methylated in the presence of concentrated sulfuric acid and sodium propionate (internal standard) dissolved in methanol. Derivatization was performed at 35{degree}C for 30 min before injection (0.5 mL headspace) onto a Hallcomid-Carbowax packed GLC column. Using serum or aqueous standards, the method was linear from 5 to 100 mg/dL. The limit of detection was 2.5 mg/dL. Day-to-day precision was less than 5% (CV) at 54 mg/dL formate. Formate and methanol were analyzed in 3 methanol poisonings, two of which were fatal. Formate analysis is considered important in any patient with suspected methanol poisoning who presents for medical assistance with metabolic acidosis. The extent of ocular toxicity correlates better with formate concentration than with methanol concentration.

  10. Rocket-powered high-performance liquid chromatographic analysis of plant ascorbate and glutathione.

    Science.gov (United States)

    Davey, M W; Dekempeneer, E; Keulemans, J

    2003-05-01

    We describe a robust procedure for the extraction and high-performance liquid chromatographic analysis of L-ascorbate (vitamin C), glutathione (gamma-glutamyl cysteinylglycine), and their respective oxidized forms from various plant tissues. Parameters such as the choice of extraction buffer, tissue disruption technique, sample stability, and separation conditions have all been optimized. In particular we found that the inclusion of the reducing agent dithiothreitol as a "stabilizer" in extracts with high phenolic content actually promoted oxidation of these antioxidants. Further, by using commercially available short "Rocket" HPLC columns in combination with high mobile-phase flow rates, analysis times were reduced to only 6min, making the method suitable for the high-resolution screening of large numbers of samples.

  11. Asymptotic analysis and boundary layers

    CERN Document Server

    Cousteix, Jean

    2007-01-01

    This book presents a new method of asymptotic analysis of boundary-layer problems, the Successive Complementary Expansion Method (SCEM). The first part is devoted to a general comprehensive presentation of the tools of asymptotic analysis. It gives the keys to understand a boundary-layer problem and explains the methods to construct an approximation. The second part is devoted to SCEM and its applications in fluid mechanics, including external and internal flows. The advantages of SCEM are discussed in comparison with the standard Method of Matched Asymptotic Expansions. In particular, for the first time, the theory of Interactive Boundary Layer is fully justified. With its chapter summaries, detailed derivations of results, discussed examples and fully worked out problems and solutions, the book is self-contained. It is written on a mathematical level accessible to graduate and post-graduate students of engineering and physics with a good knowledge in fluid mechanics. Researchers and practitioners will estee...

  12. Development and optimization of the procedure of gas- chromatographic elemental analysis of high-carbon solid fossil fuels

    Energy Technology Data Exchange (ETDEWEB)

    Platonov, V.V.; Shvykin, A.Y.; Proskuryakov, V.A.; Podshibyakin, S.I.; Chilachava, K.B.; Khmarin, E.M.; Solov' ev, A.S. [Tolstoy Tula State Pedagogical University, Tula (Russian Federation)

    2002-07-01

    A procedure was developed for gas-chromatographic elemental analysis of coals. The conditions of exhaustive oxidation of weighed microportions of the coals were optimized. The procedure of calculating the results of analysis was modified with the aim to improve its reproducibility.

  13. CHROMATOGRAPHIC TECHNIQUES IN PHARMACEUTICAL ANALYSIS IN POIAND: HISTORY AND THE PRESENCE ON THE BASIS OF PAPERS PUBLISHED IN SELECTED POLISH PHARMACEUTICAL JOURNALS IN XX CENTURY.

    Science.gov (United States)

    Bilek, Maciej; Namieśnik, Jacek

    2016-01-01

    For a long time, chromatographic techniques and techniques related to them have stimulated the development of new procedures in the field of pharmaceutical analysis. The newly developed methods, characterized by improved metrological parameters, allow for more accurate testing of, among others, the composition of raw materials, intermediates and final products. The chromatographic techniques also enable studies on waste generated in research laboratories and factories producing pharmaceuticals and parapharmaceuticals. Based on the review of reports published in Polish pharmaceutical journals, we assessed the impact of chromatographic techniques on the development of pharmaceutical analysis. The first chromatographic technique used in pharmaceutical analysis was a so-called capillary analysis. It was applied in the 1930s to control the identity of pharmaceutical formulations. In the 1940s and 1950s, the chromatographic techniques were mostly a subject of review publications, while their use in experimental work was rare. Paper chromatography and thin layer chromatography were introduced in the 1960s and 1970s, respectively. These new analytical tools have contributed to the intensive development of research in the field of phytochemistry and the analysis of herbal medicines. The development of colunm chromatography-based techniques, i.e., gas chromatography and high performance liquid chromatography took place in the end of 20th century. Both aforementioned techniques were widely applied in pharmaceutical analysis, for example, to assess the stability of drugs, test for impurities and degradation products as well as in pharmacokinetics studies. The first decade of 21" century was the time of new detection methods in gas and liquid chromatography. The information sources used to write this article were Polish pharmaceutical journals, both professional and scientific, originating from the interwar and post-war period, i.e., "Kronika Farmaceutyczna", "Farmacja Wsp

  14. A novel strategy for quantitative analysis of the formulated complex system using chromatographic fingerprints combined with some chemometric techniques.

    Science.gov (United States)

    Zhong, Xuan; Yan, Jun; Li, Yan-Chun; Kong, Bo; Lu, Hong-Bing; Liang, Yi-Zeng

    2014-11-28

    In this work, a novel strategy based on chromatographic fingerprints and some chemometric techniques is proposed for quantitative analysis of the formulated complex system. Here, the formulated complex system means a formulated type of complicated analytical system containing more than one kind of raw material under some concentration composition according to a certain formula. The strategy is elaborated by an example of quantitative determination of mixtures consist of three essential oils. Three key steps of the strategy are as follows: (1) remove baselines of the chromatograms; (2) align retention time; (3) conduct quantitative analysis using multivariate regression with entire chromatographic profiles. Through the determination of concentration compositions of nine mixtures arranged by uniform design, the feasibility of the proposed strategy is validated and the factors that influence the quantitative result are also discussed. This strategy is proved to be viable and the validation indicates that quantitative result obtained using this strategy mainly depends on the efficiency of the alignment method as well as chromatographic peak shape of the chromatograms. Previously, chromatographic fingerprints were only used for identification and/or recognition of some products. This work demonstrates that with the assistance of some effective chemometric techniques, chromatographic fingerprints are also potential and promising in solving quantitative problems of complex analytical systems.

  15. Recent trends in the use of organized molecular systems combined with chromatographic techniques in environmental analysis

    Energy Technology Data Exchange (ETDEWEB)

    Santana Rodriguez, Jose J.; Sosa Ferrera, Zoraida; Vega Moreno, Daura; Torres Padron, M.E.; Mahugo Santana, Cristina [University of Las Palmas de Gran Canaria, Department of Chemistry, Faculty of Marine Sciences, Las Palmas de Gran Canaria (Spain)

    2008-06-15

    The establishment of new analytical methods which improve quality and sensitivity in the determination of environmental pollutants in liquid and solid samples is demanded. The use of micellar systems have become an advantageous tool for the extraction of pollutant compounds, due to their easy handling, biodegradability, and the one-step procedure, and they are compatible with the hydroalcoholic mobile phases used in HPLC. The focus of this review is to present recently developed methods and the main trends in the use of micellar media combined with solid-phase microextraction and solid-phase extraction in the chromatographic analysis of organic compounds in different types of environmental matrix, including water, sediments, and biological samples. Selected samples illustrate the benefits of these systems in the whole of analytical process. The advantages of micellar media over conventional extractants are reduction of solvent usage, low cost, easy handling, and non-toxic procedure. (orig.)

  16. High-performance liquid chromatographic analysis of anthraquinone compounds in the Laurera benguelensis

    Science.gov (United States)

    Manojlović, N.; Marković, Z.; Gritsanapan, W.; Boonpragob, K.

    2009-09-01

    A high-performance liquid chromatographic (HPLC) method has been developed for the characterization of anthraquinone metabolites in extracts of the lichen Laurera benguelensis. With this method four anthraquinone derivatives 1,8-dihydroxy-3-methoxy-6-methylanthraquinone, 1,8-dihydroxy-3-formyl-6-methoxyanthraquinone, 1,8-dihydroxy-3-hydroxymethyl-6-methoxy-anthraquinone and 1,3,8-trihyroxy-6-methylanthraquinone can be analyzed. Components of lichen were detected by characteristic ultraviolet spectra and relative retention times. This is first report of phytochemical analysis of L. benguelensis. Importance of this research is in recognizing some new source (lichen and its extracts) as a natural emplacement of antioxidants because oxidation with free radicals or autooxidation is big problem for preservation of food products.

  17. Linear solvation energy relationships as classifiers in non-target analysis - a gas chromatographic approach.

    Science.gov (United States)

    Ulrich, Nadin; Mühlenberg, Jana; Retzbach, Heiko; Schüürmann, Gerrit; Brack, Werner

    2012-11-16

    Linear solvation energy relationships (LSERs) are applied as classifiers to predict the logarithmic retention factors logk from the structures of candidate compounds in non-target analysis. By comparison of the predicted value with the experimentally determined logk, progressive exclusion of candidates is done. The approach is based on the determination of stationary phase parameters to describe ten different gas chromatographic columns under four isothermal conditions. To demonstrate retention prediction and the application of the classifier model, twelve compounds with the molecular formula C(12)H(10)O(2) were selected, while experimental logk values were compared to the predicted values and exclusion of potential candidate compounds was performed. The analytical power of the approach was demonstrated on the basis of experimentally determined compound descriptors achieved from gas chromatographic measurements. The prediction got less accurate when calculated compound descriptors were employed. For the time being insufficient precision in estimating the descriptors limits the possibility to exclude candidate compounds in non-target analysis. It is expected that new approaches to estimate compound descriptors, will improve this situation. At present, the insufficient accuracy of descriptor estimates can be dealt with larger prognosis intervals. Furthermore, the combination of two stationary phases with corresponding retention prediction further advanced the exclusion of potential candidates. The most appropriate pair of stationary phases was selected by the application of four different orthogonal strategies. In addition, the classifier was applied for a validation set with different molecular composition, where column selection was considered on the basis of the differences in the compound descriptors of the corresponding candidate compounds.

  18. Comparative study of different chromatographic techniques for the analysis of multi-residues of some approved antimicrobials in fish tissues.

    Science.gov (United States)

    Riad, Safa'a M; Rezk, Mamdouh R; Khattab, Fatma I; Marzouk, Hoda M

    2015-01-01

    Two chromatographic methods were developed, optimized and validated for the simultaneous determination of three approved aquaculture antimicrobials, namely sulphadimethoxine sodium, trimethoprim and florphenicol in fish tissues. The developed methods were based on simple liquid extraction technique. The first method employs thin-layer chromatography as a clean-up procedure coupled with densitometric determination for the separated drugs. The second method is an HPLC one using X-Terra™ C18 column. Several mobile-phase systems and extracting solvents were tried to optimize the separation and the extraction procedures from fish tissues. The procedures were applied for the analysis of spiked fish tissue samples at three different concentration levels (10, 50 and 100 ppm). A comparative study was conducted between the proposed methods to discuss the advantage of each one. The methods were validated according to the international conference on harmonization guidelines. The proposed methods were successfully applied for the determination of the studied drugs in spiked fish tissues, pure powders and in their veterinary pharmaceutical formulation.

  19. Full second order chromatographic/spectrometric data matrices for automated sample identification and component analysis by non-data-reducing image analysis

    DEFF Research Database (Denmark)

    Nielsen, Niles-Peter Vest; Smedsgaard, Jørn; Frisvad, Jens Christian

    1999-01-01

    A data analysis method is proposed for identification and for confirmation of classification schemes, based on single- or multiple-wavelength chromatographic profiles. The proposed method works directly on the chromatographic data without data reduction procedures such as peak area or retention...... index calculation, Chromatographic matrices from analysis of previously identified samples are used for generating a reference chromatogram for each class, and unidentified samples are compared with all reference chromatograms by calculating a resemblance measure for each reference. Once the method...... yielded over 90% agreement with accepted classifications. The method is highly accurate and may be used on all sorts of chromatographic profiles. Characteristic component analysis yielded results in good agreement with existing knowledge of characteristic components, but also succeeded in identifying new...

  20. Abnormal tyrosine and phenylalanine metabolism in patients with tyrosyluria and phenylketonuria; gas-liquid chromatographic analysis of urinary metabolites

    NARCIS (Netherlands)

    Wadman, S.K.; Heiden, C. van der; Ketting, D.; Sprang, F.J. van

    1971-01-01

    Gas-liquid chromatographic methods have been developed for the analysis of: urinary phenylalanine metabolites (I) in patients with phenylketonuria, tyrosine metabolites (II) in patients with a disturbed tyrosine metabolism at the level of p-hydroxyphenylpyruvate hydroxylase, and homogentisic acid in

  1. Authentication of geographical origin of palm oil by chromatographic fingerprinting of triacylglycerols and partial least square-discriminant analysis.

    Science.gov (United States)

    Ruiz-Samblás, Cristina; Arrebola-Pascual, Cristina; Tres, Alba; van Ruth, Saskia; Cuadros-Rodríguez, Luis

    2013-11-15

    Main goals of the present work were to develop authentication models based on liquid and gas chromatographic fingerprinting of triacylglycerols (TAGs) from palm oil of different geographical origins in order to compare them. For this purpose, a set of palm oil samples were collected from different continents: South eastern Asia, Africa and South America. For the analysis of the information in these fingerprint profiles, a pattern recognition technique such as partial least square discriminant analysis (PLS-DA) was applied to discriminate the geographical origin of these oils, at continent level. The liquid chromatography, coupled to a charged aerosol detector, (HPLC-CAD) TAGs separation was optimized in terms of mobile phase composition and by means of a solid silica core column. The gas chromatographic method with a mass spectrometer was applied under high temperature (HTGC-MS) in order to analyze the intact TAGs. Satisfactory chromatographic resolution within a short total analysis time was achieved with both chromatographic approaches and without any prior sample treatment. The rates of successful in prediction of the geographical origin of the 85 samples varied between 70% and 100%.

  2. Ambient formaldehyde measurements made at a remote marine boundary layer site during the NAMBLEX campaign – a comparison of data from chromatographic and modified Hantzsch techniques

    Directory of Open Access Journals (Sweden)

    T. J. Still

    2006-01-01

    Full Text Available Ambient formaldehyde concentrations are reported from the North Atlantic Marine Boundary Layer Experiment (NAMBLEX campaign at Mace Head on the west coast of Eire during August 2002. The results from two techniques, using direct determination via gas chromatography and the Hantzsch technique, show similar trends but a significant off set in concentrations. For westerly air flows characteristic of the marine boundary layer, formaldehyde concentrations from the gas chromatographic and Hantzsch technique ranged from 0.78–1.15 ppb and 0.13–0.43 ppb, respectively. Possible reasons for the discrepancy have been investigated and are discussed, however, no satisfactory explanation has yet been found. In a subsequent laboratory intercomparison the two techniques were in good agreement. The observed concentrations have been compared with previous formaldehyde measurements in the North Atlantic marine boundary layer and with other measurements from the NAMBLEX campaign. The measurements from the Hantzsch technique and the GC results lie at the lower and upper ends respectively of previous measurements. In contrast to some previous measurements, both techniques show distinct diurnal profiles with day maxima and with an amplitude of approximately 0.15 ppb. Strong correlations were observed with ethanal concentrations measured during NAMBLEX and the ratio of ethanal to formaldehyde determined by the gas chromatographic technique is in good agreement with previous measurements. Some simple box modelling has been undertaken to investigate possible sources of formaldehyde. Such models are not able to predict absolute formaldehyde concentrations as they do not include transport processes, but the results show that oxygenated VOCs such as ethanal and methanol are very significant sources of formaldehyde in the air masses reaching Mace Head.

  3. Quantitative analysis combined with chromatographic fingerprint for comprehensive evaluation of Xiaoer Chaigui Tuire granules by HPLC-DAD.

    Science.gov (United States)

    Liu, Hong-Ming; Nie, Lei

    2015-01-01

    Quantitative analysis of eight major components combined with chromatographic fingerprint based on high performance liquid chromatography coupled with diode array detector (HPLC-DAD) was developed for the quality evaluation of Xiaoer Chaigui Tuire granules (XCTG), a traditional Chinese medicine (TCM) preparation. Each compound was analyzed by comparing its retention time and UV spectrum of each chromatographic peak with the corresponding retention time and UV spectrum of each standard compound. Baseline separation was achieved on an Agilent Zorbax SB-C18 column with gradient elution of acetonitrile and 0.1% (v/v) phosphoric acid. The developed method was validated by linearity, precision, repeatability, stability and recovery and was subsequently applied to quality evaluation of 12 batches of XCTG with similarity analysis, principal component analysis and cluster analysis. Quantitative analysis combined with HPLC fingerprint could offer an efficient, reliable and practical approach for quality evaluation of XCTG.

  4. Chemometric Analysis of Some Biologically Active Groups of Drugs on the Basis Chromatographic and Molecular Modeling Data.

    Science.gov (United States)

    Stasiak, Jolanta; Koba, Marcin; Baczek, Tomasz; Bucinski, Adam

    2015-01-01

    In this work, three different groups of drugs such as 12 analgesic drugs, 11 cardiovascular system drugs and 36 "other" compounds, respectively, were analyzed with cluster analysis (CA), principal component analysis (PCA) and factor analysis (FA) methods. All chemometric analysis were based on the chromatographic parameters (logk and logk(w)) determined by means of high-performance liquid chromatography (HPLC) and also by molecular modeling descriptors calculated using various computer programs (HyperChem, Dragon, and the VCCLAB). The clustering of compounds were obtained by CA (using various algorithm as e.g. Ward method or unweighted pair-group method using arithmetic averages as well as Euclidean or Manhattan distance), and allowed to build dendrograms linked drugs with similar physicochemical and pharmacological properties were discussed. Moreover, the analysis performed for analyzed groups of compounds with the use of FA or PCA methods indicated that almost all information reached in input chromatographic parameters as well as in molecular modeling descriptors can be explained by first two factors. Additionally, all analyzed drugs were clustered according to their chemical structure and pharmacological activity. Summarized, the performed classification analysis of studied drugs was focused on similarities and differences in methods being used for chemometric analysis as well as focused abilities to drugs classification (clustering) according to their molecular structures and pharmacological activity performed on the basis of chromatographic experimental and molecular modeling data. Thus, the most important application of statistically important molecular descriptors taken from QSRR models to classification analysis allow detailed biological (pharmacological) classification of analyzed drugs.

  5. Gas chromatographic analysis of simmondsins and simmondsin ferulates in jojoba meal.

    Science.gov (United States)

    Van Boven, M; Holser, R; Cokelaere, M; Flo, G; Decuypere, E

    2000-09-01

    A capillary gas chromatographic method was developed for the simultaneous determination of simmondsins and simmondsin ferulates in jojoba meal, in detoxified jojoba meal, in jojoba meal extracts, and in animal food mixtures.

  6. Development and Validation of a Chromatographic Method for the Analysis of Multicompound Pharmaceutical Preparations

    OpenAIRE

    Ferreyra, Carola; Ortiz, Cristina; Bertorello, M. M. De

    2000-01-01

    A reverse phase high performance liquid chromatographic assay was carried out for the simultaneous determination of two out of three active principles present in a pharmaceutical preparation. This method was developed to assess the quality of the product.

  7. Antimicrobial Activity and Chromatographic Analysis of Extracts from Tropaeolum pentaphyllum Lam. Tubers

    Directory of Open Access Journals (Sweden)

    Ritiel Corrêa da Cruz

    2016-04-01

    Full Text Available Background: Tropaeolum pentaphyllum Lam. tubers (Tropaeolaceae are known and used as a condiment and for the treatment of skin infections in Southern Brazil. However, its activity and composition has not yet been investigated. Thus, different extracts and the essential oil from the tubers were tested against a range of microorganisms. The most active extracts were submitted to chromatographic analysis. Methods: Hydroalcoholic extract (70%, fractions of it, and the essential oil from the tubers were tested against several bacteria, yeasts and molds, furnishing the corresponding inhibitory, bactericidal and fungicidal minimal concentration values. The most active extracts were submitted to GC-MS investigation. Results: The strongest effects against different strains of microorganisms, such as Gram-positive and negative bacteria, Candida spp. and dermatophytes were observed for the essential oil and the chloroform fraction, with minimal inhibitory concentrations (MICs well below 200 µg/mL. GC-MS analysis revealed that the major essential oil constituent is benzyl isothiocyanate (BITC, while the chloroform fraction is constituted of BITC, amides, sulfur, fatty acids and its esters, all compounds that may be related to the demonstrated activity. Conclusions: Overall, the results support the popular use of the plant for the treatment of skin infections, and revealed the main active compounds.

  8. Fuzzy C-means clustering for chromatographic fingerprints analysis: A gas chromatography-mass spectrometry case study.

    Science.gov (United States)

    Parastar, Hadi; Bazrafshan, Alisina

    2016-03-18

    Fuzzy C-means clustering (FCM) is proposed as a promising method for the clustering of chromatographic fingerprints of complex samples, such as essential oils. As an example, secondary metabolites of 14 citrus leaves samples are extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). The obtained chromatographic fingerprints are divided to desired number of chromatographic regions. Owing to the fact that chromatographic problems, such as elution time shift and peak overlap can significantly affect the clustering results, therefore, each chromatographic region is analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) to address these problems. Then, the resolved elution profiles are used to make a new data matrix based on peak areas of pure components to cluster by FCM. The FCM clustering parameters (i.e., fuzziness coefficient and number of cluster) are optimized by two different methods of partial least squares (PLS) as a conventional method and minimization of FCM objective function as our new idea. The results showed that minimization of FCM objective function is an easier and better way to optimize FCM clustering parameters. Then, the optimized FCM clustering algorithm is used to cluster samples and variables to figure out the similarities and dissimilarities among samples and to find discriminant secondary metabolites in each cluster (chemotype). Finally, the FCM clustering results are compared with those of principal component analysis (PCA), hierarchical cluster analysis (HCA) and Kohonon maps. The results confirmed the outperformance of FCM over the frequently used clustering algorithms. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Assessing the effect of data pretreatment procedures for principal components analysis of chromatographic data.

    Science.gov (United States)

    McIlroy, John W; Smith, Ruth Waddell; McGuffin, Victoria L

    2015-12-01

    Following publication of the National Academy of Sciences report "Strengthening Forensic Science in the United States: A Path Forward", there has been increasing interest in the application of multivariate statistical procedures for the evaluation of forensic evidence. However, prior to statistical analysis, variance from sources other than the sample must be minimized through application of data pretreatment procedures. This is necessary to ensure that subsequent statistical analysis of the data provides meaningful results. The purpose of this work was to evaluate the effect of pretreatment procedures on multivariate statistical analysis of chromatographic data obtained for a reference set of diesel fuels. Diesel was selected due to its chemical complexity and forensic relevance, both for fire debris and environmental forensic applications. Principal components analysis (PCA) was applied to the untreated chromatograms to assess association of replicates and discrimination among the different diesel samples. The chromatograms were then pretreated by sequentially applying the following procedures: background correction, smoothing, retention-time alignment, and normalization. The effect of each procedure on association and discrimination was evaluated based on the association of replicates in the PCA scores plot. For these data, background correction and smoothing offered minimal improvement, whereas alignment and normalization offered the greatest improvement in the association of replicates and discrimination among highly similar samples. Further, prior to pretreatment, the first principal component accounted for only non-sample sources of variance. Following pretreatment, these sources were minimized and the first principal component accounted for significant chemical differences among the diesel samples. These results highlight the need for pretreatment procedures and provide a metric to assess the effect of pretreatment on subsequent multivariate statistical

  10. Validation of a column liquid chromatographic method for the analysis of pramipexole and its five impurities.

    Science.gov (United States)

    Malenović, Andjelija; Janić-Stojanović, Biljana; Vemić, Ana; Ivanović, Darko; Medenica, Mirjana

    2010-01-01

    In this paper, a previously optimized method for HPLC analysis of pramipexole and its impurities was subjected to method validation in accordance with official regulations. The optimized chromatographic conditions were as follows: mobile phase acetonitrile-water phase [15 + 85, v/v, water phase contained 1% triethylamine (TEA), pH adjusted to 7.0 with orthophosphoric acid]; detection at 262 nm for pramipexole, BI-II 751 xx, BI-I 786 BS, BI-II 820 BS, and 2-aminobenzothiazole and at 326 nm for BI-II 546 CL; column temperature, 25 degrees C; and flow rate, 1 ml/min. Acetonitrile and TEA content, pH of the water phase, flow rate, column temperature, and column type were factors studied in robustness testing. According to the experimental plan defined by a Plackett-Burman design, five dummy variables were added in order to have 12 factors. As output, resolution factor was chosen. Robustness was assessed by graphical (half-normal probability plots and Pareto charts) and statistical (t-test) methods. Also, nonsignificance intervals for significant factors were estimated, and limits for the system suitability test were determined. Finally, linearity, accuracy, and precision of the proposed HPLC method were defined. LOD and LOQ values for analyzed impurities were determined. The method was completely defined by these experiments.

  11. High-performance liquid chromatographic analysis and pharmacokinetics of terazosin in healthy volunteers.

    Science.gov (United States)

    Kang, B C; Yang, C Q; Rhee, J E; Suh, O K; Shin, W G

    2001-01-01

    A high-performance liquid chromatographic (HPLC) analysis of terazosin in 1 ml of human plasma was developed using prazosin as an internal standard. The plasma sample was extracted with dichloromethane and ethylether and a 100-microl aliquot was injected onto the reversed-phase column. The mobile phase, 0.02 M sodium phosphate buffer:acetonitrile:tetrahydrofuran = 720:220:60 (v/v/v), was run at a flow rate of 0.8 ml/min and the column effluent was monitored using a florescence detector set at 370 and 250 nm for the emission and excitation wave numbers, respectively. The retention times for terazosin and prazosin were approximately 6.4 and 9.8 min, respectively, and the coefficients of variation of terazosin were generally low, below 6.4%. The present HPLC method was successful for the pharmacokinetic study of terazosin in healthy volunteers. Following oral administration of terazosin, 2 mg, to 20 healthy male volunteers, the area under the plasma concentration-time curve from time zero to time infinity was 421 +/- 71.8 ng h/ml and terminal half-life was 9.83 +/- 1.29 h.

  12. Application of Gas Chromatographic analysis to RPC detectors in the ATLAS experiment at CERN-LHC

    CERN Document Server

    De Asmundis, R

    2007-01-01

    Starting from 2007 a large number (1200) Resistive Plate Chambers (RPC) detectors will be used as muon trigger detectors in the ATLAS Experiment at CERN-LHC accelerator. RPC are gaseous detector in which the quality and the stability of the gas mixture as well as the design of the gas supplying system, play a fundamental role in their functioning. RPC are foreseen to work more than ten years in the high radiation environment of ATLAS and the gas mixture acts really as a "lifeguard" for the detectors. For this reason a great attention has been devoted to the gas studies in order to optimize RPC performance, robustness and reliability in a high radiation environment. In this paper we describe the work done to decide how to supply and control in an optimal way the gas to the detectors, in order to ensure their best performance for a long time. The activity, based on Gas Chromatographic (GC) analysis, has been carried on a sample of final RPC working in radiation conditions much more intense than those foreseen f...

  13. Gas chromatographic quantitative analysis of methanol in wine: operative conditions, optimization and calibration model choice.

    Science.gov (United States)

    Caruso, Rosario; Gambino, Grazia Laura; Scordino, Monica; Sabatino, Leonardo; Traulo, Pasqualino; Gagliano, Giacomo

    2011-12-01

    The influence of the wine distillation process on methanol content has been determined by quantitative analysis using gas chromatographic flame ionization (GC-FID) detection. A comparative study between direct injection of diluted wine and injection of distilled wine was performed. The distillation process does not affect methanol quantification in wines in proportions higher than 10%. While quantification performed on distilled samples gives more reliable results, a screening method for wine injection after a 1:5 water dilution could be employed. The proposed technique was found to be a compromise between the time consuming distillation process and direct wine injection. In the studied calibration range, the stability of the volatile compounds in the reference solution is concentration-dependent. The stability is higher in the less concentrated reference solution. To shorten the operation time, a stronger temperature ramp and carrier flow rate was employed. With these conditions, helium consumption and column thermal stress were increased. However, detection limits, calibration limits, and analytical method performances are not affected substantially by changing from normal to forced GC conditions. Statistical data evaluation were made using both ordinary (OLS) and bivariate least squares (BLS) calibration models. Further confirmation was obtained that limit of detection (LOD) values, calculated according to the 3sigma approach, are lower than the respective Hubaux-Vos (H-V) calculation method. H-V LOD depends upon background noise, calibration parameters and the number of reference standard solutions employed in producing the calibration curve. These remarks are confirmed by both calibration models used.

  14. Optimization and Assessment of Three Different High Performance Liquid Chromatographic Systems for the Combinative Fingerprint Analysis and Multi-Ingredients Quantification of Sangju Ganmao Tablet.

    Science.gov (United States)

    Guo, Meng-Zhe; Han, Jie; He, Dan-Dan; Zou, Jia-Hui; Li, Zheng; Du, Yan; Tang, Dao-Quan

    2017-03-01

    Chromatographic separation is still a critical subject for the quality control of traditional Chinese medicine. In this study, three different high performance liquid chromatographic (HPLC) systems employing commercially available columns packed with 1.8, 3.5 and 5.0 μm particles were respectively developed and optimized for the combinative fingerprint analysis and multi-ingredients quantification of Sangju Ganmao tablet (SGT). Chromatographic parameters including the repeatability of retention time and peak area, symmetry factor, resolution, number of theoretical plates and peak capacity were used to assess the chromatographic performance of different HPLC systems. The optimal chromatographic system using Agilent ZORBAX SB-C18 column (2.1 mm × 100 mm, 3.5 μm) as stationary phase was respectively coupled with diode array detector or mass spectrometry detector for the chromatographic fingerprint analysis and simultaneous quantification or identification of nine compounds of SGT. All the validation data conformed to the acceptable requirements. For the fingerprint analysis, 31 peaks were selected as the common peaks to evaluate the similarities of SGT from 10 different manufacturers using heatmap, hierarchical cluster analysis and principal component analysis. The results demonstrated that the combinations of the quantitative and chromatographic fingerprint analysis offer an efficient way to evaluate the quality consistency of SGT.

  15. Simultaneous chromatographic fingerprinting and quantitative analysis of flavonoids in Pollen Typhae by high-performance capillary electrophoresis

    Directory of Open Access Journals (Sweden)

    Le Han

    2012-12-01

    Full Text Available To evaluate the quality of Pollen Typhae as used in traditional Chinese medicine, a high-performance capillary electrophoresis (HPCE method has been developed, validated and applied to chromatographic fingerprinting and quantitation of its eight main bioactive flavonoids (naringenin, isorhamnetin 3-O-(2G-α-l-rhamnosyl-rutinoside, rhamnetin 3-O-neohesperidoside, isorhamnetin, quercetin 3-O-(2G-α-l-rhamnosyl-rutinoside, quercetin 3-O-neohesperidoside, kaempferol and quercetin. Fingerprinting was based on the selection of nine characteristic chromatographic peaks. In quantitative analysis, the recovery of all eight compounds was in the range 98.5–102.2% with good linearity (r2>0.9919 over a relatively wide concentration range. The assay was successfully applied to the analysis of the eight bioactive flavonoids in 14 different samples. The results indicate that the assay is reproducible and precise and can be used for convenient quality assessment of Pollen Typhae.

  16. Layer-by-Layer Proteomic Analysis of Mytilus galloprovincialis Shell.

    Directory of Open Access Journals (Sweden)

    Peng Gao

    Full Text Available Bivalve shell is a biomineralized tissue with various layers/microstructures and excellent mechanical properties. Shell matrix proteins (SMPs pervade and envelop the mineral crystals and play essential roles in biomineralization. Despite that Mytilus is an economically important bivalve, only few proteomic studies have been performed for the shell, and current knowledge of the SMP set responsible for different shell layers of Mytilus remains largely patchy. In this study, we observed that Mytilus galloprovincialis shell contained three layers, including nacre, fibrous prism, and myostracum that is involved in shell-muscle attachment. A parallel proteomic analysis was performed for these three layers. By combining LC-MS/MS analysis with Mytilus EST database interrogations, a whole set of 113 proteins was identified, and the distribution of these proteins in different shell layers followed a mosaic pattern. For each layer, about a half of identified proteins are unique and the others are shared by two or all of three layers. This is the first description of the protein set exclusive to nacre, myostracum, and fibrous prism in Mytilus shell. Moreover, most of identified proteins in the present study are novel SMPs, which greatly extended biomineralization-related protein data of Mytilus. These results are useful, on one hand, for understanding the roles of SMPs in the deposition of different shell layers. On the other hand, the identified protein set of myostracum provides candidates for further exploring the mechanism of adductor muscle-shell attachment.

  17. Layer-by-Layer Proteomic Analysis of Mytilus galloprovincialis Shell

    Science.gov (United States)

    Wang, Xin-xing; Bao, Lin-fei; Fan, Mei-hua; Li, Xiao-min; Wu, Chang-wen; Xia, Shu-wei

    2015-01-01

    Bivalve shell is a biomineralized tissue with various layers/microstructures and excellent mechanical properties. Shell matrix proteins (SMPs) pervade and envelop the mineral crystals and play essential roles in biomineralization. Despite that Mytilus is an economically important bivalve, only few proteomic studies have been performed for the shell, and current knowledge of the SMP set responsible for different shell layers of Mytilus remains largely patchy. In this study, we observed that Mytilus galloprovincialis shell contained three layers, including nacre, fibrous prism, and myostracum that is involved in shell-muscle attachment. A parallel proteomic analysis was performed for these three layers. By combining LC-MS/MS analysis with Mytilus EST database interrogations, a whole set of 113 proteins was identified, and the distribution of these proteins in different shell layers followed a mosaic pattern. For each layer, about a half of identified proteins are unique and the others are shared by two or all of three layers. This is the first description of the protein set exclusive to nacre, myostracum, and fibrous prism in Mytilus shell. Moreover, most of identified proteins in the present study are novel SMPs, which greatly extended biomineralization-related protein data of Mytilus. These results are useful, on one hand, for understanding the roles of SMPs in the deposition of different shell layers. On the other hand, the identified protein set of myostracum provides candidates for further exploring the mechanism of adductor muscle-shell attachment. PMID:26218932

  18. Layer-by-Layer Proteomic Analysis of Mytilus galloprovincialis Shell.

    Science.gov (United States)

    Gao, Peng; Liao, Zhi; Wang, Xin-Xing; Bao, Lin-Fei; Fan, Mei-Hua; Li, Xiao-Min; Wu, Chang-Wen; Xia, Shu-Wei

    2015-01-01

    Bivalve shell is a biomineralized tissue with various layers/microstructures and excellent mechanical properties. Shell matrix proteins (SMPs) pervade and envelop the mineral crystals and play essential roles in biomineralization. Despite that Mytilus is an economically important bivalve, only few proteomic studies have been performed for the shell, and current knowledge of the SMP set responsible for different shell layers of Mytilus remains largely patchy. In this study, we observed that Mytilus galloprovincialis shell contained three layers, including nacre, fibrous prism, and myostracum that is involved in shell-muscle attachment. A parallel proteomic analysis was performed for these three layers. By combining LC-MS/MS analysis with Mytilus EST database interrogations, a whole set of 113 proteins was identified, and the distribution of these proteins in different shell layers followed a mosaic pattern. For each layer, about a half of identified proteins are unique and the others are shared by two or all of three layers. This is the first description of the protein set exclusive to nacre, myostracum, and fibrous prism in Mytilus shell. Moreover, most of identified proteins in the present study are novel SMPs, which greatly extended biomineralization-related protein data of Mytilus. These results are useful, on one hand, for understanding the roles of SMPs in the deposition of different shell layers. On the other hand, the identified protein set of myostracum provides candidates for further exploring the mechanism of adductor muscle-shell attachment.

  19. Development and validation of a reversed-phase liquid chromatographic method for analysis of demeclocycline and related impurities.

    Science.gov (United States)

    Kahsay, Getu; Maxa, Jaroslav; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

    2012-06-01

    A simple, robust, and rapid reversedphase high-performance liquid chromatographic method for the analysis of demeclocycline and its impurities is described. Chromatographic separations were achieved on a Symmetry Shield RP8 (75 mm × 4.6 mm, 3.5 μm) column kept at 40°C. The mobile phase was a gradient mixture of acetonitrile, 0.06 M sodium edetate (pH 7.5), 0.06 M tetrapropylammonium hydrogen sulphate (pH 7.5) and water, A (2:35:35:28 v/v/v/v) and B (30:35:35:0 v/v/v/v) pumped at a flow rate of 1 mL/min. UV detection was performed at 280 nm. The developed method was validated according to the ICH guidelines for specificity, limit of detection, limit of quantification, linearity, precision, and robustness. An experimental design was applied for robustness study. Results show that the peak shape, chromatographic resolution between the impurities, and the total analysis time are satisfactory and better than previous methods. The method has been applied for the analysis of commercial demeclocycline bulk samples available on the market.

  20. Comparison of two gas-liquid chromatograph columns for the analysis of fatty acids in ruminant meat.

    Science.gov (United States)

    Alves, Susana P; Bessa, Rui J B

    2009-06-26

    Two gas-liquid chromatograph capillary columns for the analysis of fatty acids (FA) in ruminant fat are compared. Those columns are the CP-Sil 88 of 100 m long with a highly polar stationary phase and the Omegawax 250 of 30 m long with a stationary phase of intermediate polarity. Fatty acid methyl ester (FAME) patterns of branched-chain, cis and trans octadecenoate isomers, as well as conjugated and non-conjugated 18:2 and 18:3 isomers are fairly different between columns, even though most of the FAME could be separated on either column. However, the CP-Sil 88 showed better resolution of 18:1 isomers than Omegawax 250. The analysis of 96 samples of ruminant meat fat in both chromatographic systems showed that averages obtained for total FA content and for most of the individual FA did not differ between columns. Moreover, regression analysis of Omegawax and CP-Sil 88 data is highly correlated. Quantitative differences between chromatographic systems were detected for samples containing more than 66 mg fatty acids per gram of muscle dry matter.

  1. Quantitative HPLC-ICP-MS analysis of antimony redox speciation in complex sample matrices: new insights into the Sb-chemistry causing poor chromatographic recoveries

    DEFF Research Database (Denmark)

    Hansen, Claus; Schmidt, Bjørn; Larsen, Erik Huusfeldt;

    2011-01-01

    In solution antimony exists either in the pentavalent or trivalent oxidation state. As Sb(III) is more toxic than Sb(V), it is important to be able to perform a quantitative speciation analysis of Sb’s oxidation state. The most commonly applied chromatographic methods used for this redox speciation...... analysis do, however, often show a low chromatographic Sb recovery when samples of environmental or biological origin are analysed. In this study we explored basal chemistry of antimony and found that formation of macromolecules, presumably oligomeric and polymeric Sb(V) species, is the primary cause...... of low chromatographic recoveries. A combination of HPLC-ICP-MS, AFFF-ICP-MS and spinfiltration was applied for analysis of model compounds and biological samples. Quantitative chromatographic Sb redox speciation analysis was possible by acidic hydrolysis of the antimony polymers prior to analysis...

  2. Programmed automation of modulator cold jet flow for comprehensive two-dimensional gas chromatographic analysis of vacuum gas oils.

    Science.gov (United States)

    Rathbun, Wayne

    2007-01-01

    A method is described for automating the regulation of cold jet flow of a comprehensive two-dimensional gas chromatograph (GCxGC) configured with flame ionization detection. This new capability enables the routine automated separation, identification, and quantitation of hydrocarbon types in petroleum fractions extending into the vacuum gas oil (VGO) range (IBP-540 degrees C). Chromatographic data acquisition software is programmed to precisely change the rate of flow from the cold jet of a nitrogen cooled loop modulator of a GCxGC instrument during sample analysis. This provides for the proper modulation of sample compounds across a wider boiling range. The boiling point distribution of the GCxGC separation is shown to be consistent with high temperature simulated distillation results indicating recovery of higher boiling semi-volatile VGO sample components. GCxGC configured with time-of-flight mass spectrometry is used to determine the molecular identity of individual sample components and boundaries of different molecular types.

  3. Multivariate analysis of FTIR and ion chromatographic data for the quality control of tequila.

    Science.gov (United States)

    Lachenmeier, Dirk W; Richling, Elke; López, Mercedes G; Frank, Willi; Schreier, Peter

    2005-03-23

    Principal component analysis (PCA) was applied to the chromatographic and spectroscopic data of authentic Mexican tequilas (n = 14) and commercially available samples purchased in Mexico and Germany (n = 24). The scores scatter plot of the first two principal components (PC) of the anions chloride, nitrate, sulfate, acetate, and oxalate accounting for 78% of the variability allowed a classification between tequilas bottled in Mexico and overseas; however, no discrimination between tequila categories was possible. Mexican products had a significantly (p = 0.0014) lower inorganic anion concentration (range = 1.5-5.1 mg/L; mean = 2.5 mg/L) than the products bottled in the importing countries (range = 3.3-62.6 mg/L; mean = 26.3 mg/L). FTIR allowed a rapid screening of density and ethanol as well as the volatile compounds methanol, ethyl acetate, propanol-1, isobutanol, and 2-/3-methyl-1-butanol using partial least-squares regression (precisions = 5.3-29.3%). Using PCA of the volatile compounds, a differentiation between tequila derived from "100% agave" (Agave tequilana Weber var. azul, Agavaceae) and tequila produced with other fermentable sugars ("mixed"tequila) was possible. The first two PCs describe 89% of the total variability of the data. Methanol and isobutanol influenced the variability in PC1, which led to discrimination. The concentrations of methanol and isobutanol were significantly higher (methanol, p = 0.004; isobutanol, p = 0.005) in the 100% agave (methanol, 297.9 +/- 49.5; isobutanol, 251.3 +/- 34.9) than in the mixed tequilas (methanol, 197.8 +/- 118.5; isobutanol, 151.4 +/- 52.8).

  4. High Performance Liquid Chromatographic Analysis of Phytoplankton Pigments Using a C16-Amide Column

    Science.gov (United States)

    A reverse-phase high performance liquid chromatographic (RP-HPLC) method was developed to analyze in a single run, most polar and non-polar chlorophylls and carotenoids from marine phytoplankton. The method is based on a RP-C16-Amide column and a ternary gradient system consistin...

  5. Piper nigrum: micropropagation, antioxidative enzyme activities, and chromatographic fingerprint analysis for quality control.

    Science.gov (United States)

    Ahmad, Nisar; Abbasi, Bilal Haider; Rahman, Inayat ur; Fazal, Hina

    2013-04-01

    A reliable in vitro regeneration system for the economical and medicinally important Piper nigrum L. has been established. Callus and shoot regeneration was encouraged from leaf portions on Murashige and Skoog (MS) medium augmented with varied concentrations of plant growth regulators. A higher callus production (90 %) was observed in explants incubated on MS medium incorporated with 1.0 mg L(-1) 6-benzyladenine (BA) along with 0.5 mg L(-1) gibberellic acid after 4 weeks of culture. Moreover, a callogenic response of 85 % was also recorded for 1.0 mg L(-1) BA in combination with 0.25 mg L(-1) α-naphthalene acetic acid (NAA) and 0.25 mg L(-1) 2,4-dichlorophenoxyacetic acid or 0.5 mg L(-1) indole butyric acid (IBA) along with 0.25 mg L(-1) NAA and indole acetic acid. Subsequent sub-culturing of callus after 4 weeks of culture onto MS medium supplemented with 1.5 mg L(-1) thiodiazoran or 1.5 mg L(-1) IBA induced 100 % shoot response. Rooted plantlets were achieved on medium containing varied concentrations of auxins. The antioxidative enzyme activities [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)] revealed that significantly higher SOD was observed in regenerated plantlets than in other tissues. However, POD, CAT, and APX were higher in callus than in other tissues. A high-performance liquid chromatography (HPLC) fingerprint analysis protocol was established for quality control in different in vitro-regenerated tissues of P. nigrum L. During analysis, most of the common peaks represent the active principle "piperine." The chemical contents, especially piperine, showed variation from callus culture to whole plantlet regeneration. Based on the deviation in chromatographic peaks, the in vitro-regenerated plantlets exhibit a nearly similar piperine profile to acclimated plantlets. The in vitro regeneration system and HPLC fingerprint analysis established here brought a novel approach to the quality control of in vitro

  6. Microstructure-based analysis and simulation of flow and mass transfer in chromatographic stationary phases

    Science.gov (United States)

    Koku, Harun

    Limitations of mass transfer in chromatographic bioseparations employing traditional packed particles have fuelled the inception and development of alternative stationary phases with improved performance characteristics. This work investigates case studies in two categories of these alternative media, namely polymer-modified packed particles and continuous monolithic phases, for insight into their enhanced properties. Specifically, high-resolution microscopy techniques and image-based analysis algorithms were implemented to extract morphology information for these materials, in an attempt to elucidate the relation between microstructure and performance. For the monolith, mesoscopic simulation methods were also employed for a more rigorous analysis of the flow and dispersion behavior. Scanning and transmission electron microscopy images of the commercial polymer-modified, agarose-based particle Sepharose XL were compared to those for its unmodified counterpart, Sepharose FF. Local regions in the composite dextran-agarose Sepharose XL particles were noted to exhibit a denser network of fibers and smaller pore sizes overall, compared to those in the traditional Sepharose FF particles. Images of particles equilibrated with high concentrations of protein revealed a significant difference in protein localization patterns, with the stained protein in XL occupying a markedly higher area fraction of the images. This suggests a higher volume available for adsorption and provides visual clues into how the consistently higher static capacity of these polymer-modified particles is manifested. Treatment of the XL particles with dextranase, an enzyme that breaks down dextran, resulted in a reduction of protein coverage, providing evidence that it is indeed the dextran that is responsible for the improved static capacity in this polymer-modified stationary phase. Imaging and image analysis techniques were also used to analyze the commercial CIM(TM) disk monolith. Two- and three

  7. Uniaxially aligned electrospun cellulose acetate nanofibers for thin layer chromatographic screening of hydroquinone and retinoic acid adulterated in cosmetics.

    Science.gov (United States)

    Tidjarat, Siripran; Winotapun, Weerapath; Opanasopit, Praneet; Ngawhirunpat, Tanasait; Rojanarata, Theerasak

    2014-11-01

    Uniaxially aligned cellulose acetate (CA) nanofibers were successfully fabricated by electrospinning and applied to use as stationary phase for thin layer chromatography. The control of alignment was achieved by using a drum collector rotating at a high speed of 6000 rpm. Spin time of 6h was used to produce the fiber thickness of about 10 μm which was adequate for good separation. Without any chemical modification after the electrospinning process, CA nanofibers could be readily devised for screening hydroquinone (HQ) and retinoic acid (RA) adulterated in cosmetics using the mobile phase consisting of 65:35:2.5 methanol/water/acetic acid. It was found that the separation run on the aligned nanofibers over a distance of 5 cm took less than 15 min which was two to three times faster than that on the non-aligned ones. On the aligned nanofibers, the masses of HQ and RA which could be visualized were 10 and 25 ng, respectively, which were two times lower than those on the non-aligned CA fibers and five times lower than those on conventional silica plates due to the appearance of darker and sharper of spots on the aligned nanofibers. Furthermore, the proposed method efficiently resolved HQ from RA and ingredients commonly found in cosmetic creams. Due to the satisfactory analytical performance, facile and inexpensive production process, uniaxially aligned electrospun CA nanofibers are promising alternative media for planar chromatography.

  8. Chromatographic analysis of water and wine samples for phenolic compounds released from food-contact epoxy resins.

    Science.gov (United States)

    Lambert, C; Larroque, M

    1997-02-01

    Food-contact epoxy resins can release phenolic compounds such as phenol, m-cresol, bisphenol F, bisphenol A, 4-tert-butylphenol, bisphenol F diglycidyl ether (BFDGE), and bisphenol A diglycidyl ether (BADGE) into foodstuffs. A validated high-performance liquid chromatographic method with fluorometric detection is described for the simultaneous analysis of these compounds in wine and mineral water. Sample preparation by solid-liquid extraction enables detection limits of 2.5 micrograms/L in wine and 0.25 microgram/L in mineral water to be achieved. Recovery rates are close to 100%, except for BFDGE and BADGE (around 60% in wine and 75% in mineral water).

  9. A Sensitive Liquid Chromatographic Method for the Analysis of Clarithromycin with Pre-Column Derivatization: Application to a Bioequivalence Study

    OpenAIRE

    Amir Farshchi; Golbarg Ghiasi; Gholamreza Bahrami

    2009-01-01

    Objective(s)A sensitive liquid chromatographic method for the analysis of clarithromycin- a macrolide antibiotic- in human serum, using pre-column derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl) is described. Materials and MethodsThe method involved liquid–liquid extraction of the drug and an internal standard (amantadine) followed by pre-column derivatization of the analytes with FMOC-Cl. A mixture of 0.05 M phosphate buffer containing triethylamine (2 ml/l; pH 3.8) and methano...

  10. Chromatographic fingerprinting analysis of Zhizhu Wan preparation by high-performance liquid chromatography coupled with photodiode array detector

    Directory of Open Access Journals (Sweden)

    Hui Sun

    2014-01-01

    Full Text Available Background: Traditional Chinese medicine (TCM formula has been used for over 1000 years and most of them contain complicate chemical constituents. Chromatographic fingerprinting has been widely accepted as a crucial method for qualitative and quantitative analyses for TCM. Zhi Zhu Wan (ZZW, a classical Chinese medical formula, has been commonly used for the treatment of gastrointestinal disease, which pose a serious challenge to its quality control. Materials and Methods: In this work, a sensitive and reliable method of high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA was developed to control the quality of ZZW for chemical fingerprint analysis and quantitative analysis of four major bioactive constituents, including hesperidin, naringin, neohesperidin, and atractylenolide I. The chromatographic separation was performed on a Waters Symmetry C18 column (4.6 mm × 250 mm, 5 μm particle size, with an aqueous 0.095% phosphate acid and acetonitrile mobile phase gradient. Results: Optimization of other experimental conditions was validated with satisfactory accuracy, precision, repeatability, and recovery. In quantitative analysis, the four components showed good regression (R > 0.9994 within test ranges, and the recovery method ranged from 99.32% to 100.630%. HPLC fingerprints of the ZZW samples were compared by performing similarity analysis. Conclusion: The results indicated that the newly developed HPLC-PDA fingerprint method would be suitable for quality control of ZZW.

  11. Chromatographic fingerprinting analysis of Zhizhu Wan preparation by high-performance liquid chromatography coupled with photodiode array detector

    Science.gov (United States)

    Sun, Hui; Chen, Xi; Zhang, Aihua; Sakurai, Tetsuro; Jiang, Jinzhong; Wang, Xijun

    2014-01-01

    Background: Traditional Chinese medicine (TCM) formula has been used for over 1000 years and most of them contain complicate chemical constituents. Chromatographic fingerprinting has been widely accepted as a crucial method for qualitative and quantitative analyses for TCM. Zhi Zhu Wan (ZZW), a classical Chinese medical formula, has been commonly used for the treatment of gastrointestinal disease, which pose a serious challenge to its quality control. Materials and Methods: In this work, a sensitive and reliable method of high-performance liquid chromatography coupled with photodiode array detector (HPLC-PDA) was developed to control the quality of ZZW for chemical fingerprint analysis and quantitative analysis of four major bioactive constituents, including hesperidin, naringin, neohesperidin, and atractylenolide I. The chromatographic separation was performed on a Waters Symmetry C18 column (4.6 mm × 250 mm, 5 μm particle size), with an aqueous 0.095% phosphate acid and acetonitrile mobile phase gradient. Results: Optimization of other experimental conditions was validated with satisfactory accuracy, precision, repeatability, and recovery. In quantitative analysis, the four components showed good regression (R > 0.9994) within test ranges, and the recovery method ranged from 99.32% to 100.630%. HPLC fingerprints of the ZZW samples were compared by performing similarity analysis. Conclusion: The results indicated that the newly developed HPLC-PDA fingerprint method would be suitable for quality control of ZZW. PMID:25422548

  12. Stability-indicating high-performance thin-layer chromatographic method for quantitative determination of omeprazole in capsule dosage form.

    Science.gov (United States)

    Jha, Preeta; Parveen, Rabea; Khan, Suroor A; Alam, Ozair; Ahmad, Sayeed

    2010-01-01

    A novel HPTLC method has been developed and validated for quantitative determination of omeprazole (OPZ) in capsule dosage form. The method was validated according to the International Conference on Harmonization guidelines for accuracy, precision, linearity, specificity, and robustness. HPTLC aluminum sheets precoated with silica gel 60F24 were used as the stationary phase and chloroform-methanol (9 + 1) as the mobile phase. The mobile phase was found to give compact bands for OPZ (Rf value of 0.39 +/- 0.12) in densitometric analysis in the absorbance mode at 302 nm. The linear regression analysis data for the calibration plots showed good linearity (r2 = 0.997) with respect to peak area in the concentration range 50-3000 ng/band. The mean values of the slope and intercept were 9.896 +/- 0.0753 and 1870.761 +/- 16.866, respectively. The method was also applied for stability testing of OPZ in different stress conditions and found to be accurate, linear, precise, robust, specific, and stability indicating. The method proposed can be used for QC and stability testing of different dosage forms such as tablets and capsules, as well as for bulk drug analysis of OPZ.

  13. Development of chromatographic methods for analysis of sulfamethoxazole, trimethoprim, their degradation products and preservatives in syrup

    OpenAIRE

    Perović, Ivana; Malenović, Anđelija; Vemić, Ana; Kostić, Nađa; Ivanović, Darko

    2014-01-01

    In this paper the experimental conditions for optimal reversed-phase liquid chromatographic (RP-HPLC) determination of sulfamethoxazole, trimethoprim and preservatives, as well as degradation products of sulfamethoxazole and trimethoprim in syrup were defined. The determination of active compounds and preservatives was carried out on Zorbax Eclipse XDB-C18, 150 mm × 4.6 mm, 5 μm particle size column, mobile phase flow rate was 1.5 mL min-1, and detection at 235 nm for the active compounds and...

  14. RBS analysis of electrochromic layers

    Energy Technology Data Exchange (ETDEWEB)

    Green, D.C.; Bell, J.M. [University of Technology, Sydney, NSW (Australia); Kenny, M.J.; Wielunski, L.S. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1993-12-31

    Tungsten oxide thin films produced by dip-coating from tungsten alkoxide solutions are of interest for their application in large area switchable windows. The application consists of a layer of electrochromic tungsten oxide (W0{sub 3}) on indium tin oxide (ITO) coated glass in contact with a complementary structure. Electrochromic devices are switchable between states of high and low transparency by the application of a small voltage. The mechanism relies on the dual injection of ions and electrons into the W0{sub 3} layer from adjacent layers in the device. Electrochromic tungsten oxide can be deposited using standard techniques (eg. sputtering and evaporation) but also using sol-gel deposition. Sol-gel processing has an advantage over conventional preparation techniques because of the simplicity of the equipment. The scaling up to large area coatings is also feasible. RBS and forward recoil has been used to obtain profiles for individual elements in the structure of electrochromic films. 3 refs., 3 figs.

  15. Subsurface Raman analysis of thin painted layers.

    Science.gov (United States)

    Conti, Claudia; Colombo, Chiara; Realini, Marco; Zerbi, Giuseppe; Matousek, Pavel

    2014-01-01

    Here we present, for the first time, an extension of spatially offset Raman spectroscopy to thin (tens of micrometers thick), highly turbid stratified media such as those encountered in paintings. The method permits the non-destructive interrogation of painted layers in situations where conventional Raman microscopy is not applicable due to high turbidity of the top layer(s). The concept is demonstrated by recovering the pure Raman spectra of paint sub-layers that are completely obscured by paint over-layers. Potential application areas include the analysis of paintings in art preservation and restoration avoiding the cross-sectional analysis used currently with this type of samples. The technique also holds promise for the development as a non-destructive subsurface tool for in situ analysis using portable instruments.

  16. Fully automated high-performance liquid chromatographic assay for the analysis of free catecholamines in urine.

    Science.gov (United States)

    Said, R; Robinet, D; Barbier, C; Sartre, J; Huguet, C

    1990-08-24

    A totally automated and reliable high-performance liquid chromatographic method is described for the routine determination of free catecholamines (norepinephrine, epinephrine and dopamine) in urine. The catecholamines were isolated from urine samples using small alumina columns. A standard automated method for pH adjustment of urine before the extraction step has been developed. The extraction was performed on an ASPEC (Automatic Sample Preparation with Extraction Columns, Gilson). The eluate was collected in a separate tube and then automatically injected into the chromatographic column. The catecholamines were separated by reversed-phase ion-pair liquid chromatography and quantified by fluorescence detection. No manual intervention was required during the extraction and separation procedure. One sample may be run every 15 min, ca. 96 samples in 24 h. Analytical recoveries for all three catecholamines are 63-87%, and the detection limits are 0.01, 0.01, and 0.03 microM for norepinephrine, epinephrine and dopamine, respectively, which is highly satisfactory for urine. Day-to-day coefficients of variation were less than 10%.

  17. Chromatographic fingerprinting and quantitative analysis for the quality evaluation of Xinkeshu tablet

    Institute of Scientific and Technical Information of China (English)

    Pei Wang; Lian Li; Hailong Yang; Shijuan Cheng; Yingzi Zeng; Lei Nie; Hengchang Zang

    2012-01-01

    A simple, sensitive and accurate method based on high performance liquid chromato- graphy (HPLC) with diode array detector (DAD) was developed and validated for systematic quality evaluation of one type of traditional Chinese medicine preparations named Xinkeshu (XKS) tablet. In this study, the chromatographic fingerprints of XKS tablet were developed first, 23 peaks were selected as the common peaks to evaluate the similarities among different batches of XKS samples, which were manufactured in a long time span of three years. Additionally, simultaneous quantification of six markers in XKS tablet, including Danshensu, Protocatechuic aldehyde, Puerarin, Daidzin, Salvianolic acid B and Daidzein, was performed. The validation results showed that the developed method was specific, accurate, precise and robust. The preliminary explanation on why a close similarity between fingerprints did not exactly mean similar contents of chemical components in samples was given. The contribution of each chromatographic peak to similarity was also evaluated. The developed method offers an efficient, reliable and practical approach for systematic quality evaluation of XKS tablet.

  18. A Sensitive Liquid Chromatographic Method for the Analysis of Clarithromycin with Pre-Column Derivatization: Application to a Bioequivalence Study

    Directory of Open Access Journals (Sweden)

    Amir Farshchi

    2009-03-01

    Full Text Available Objective(sA sensitive liquid chromatographic method for the analysis of clarithromycin- a macrolide antibiotic- in human serum, using pre-column derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl is described. Materials and MethodsThe method involved liquid–liquid extraction of the drug and an internal standard (amantadine followed by pre-column derivatization of the analytes with FMOC-Cl. A mixture of 0.05 M phosphate buffer containing triethylamine (2 ml/l; pH 3.8 and methanol (17:83, v/v was used as mobile phase and chromatographic separation was achieved on a Shimpack CLC-ODS column. The eluate was monitored by a fluorescence detector with respective excitation and emission wavelengths of 265 and 315 nm. ResultsThe analytical method was linear over the concentration range of 0.025-10 μg/ml of clarithromycin in human serum with a limit of quantification of 0.025 μg/ml. The assay is sensitive enough to measure drug levels obtained in human single dose studies.ConclusionIn the present method, sensitivity and the running time of analysis have been improved and successfully applied in a bioequivalence study of three different clarithromycin preparations in 12 healthy volunteers.

  19. Characterization of crude oils and petroleum products: (I Elution liquid chromatographic separation and gas chromatographic analysis of crude oils and petroleum products

    Directory of Open Access Journals (Sweden)

    E.O. Odebunmi

    2002-12-01

    Full Text Available Some physical and chemical properties of samples of light, medium and heavy Nigerian crude oils and petroleum products including gasoline, kerosene and engine oil have been measured and are reported in this paper. The crude oils and petroleum products have also been characterized by fractional distillation and elution liquid chromatography. The fractions obtained from elution liquid chromatography were analyzed using gas chromatography (GC. The GC fractions were identified by comparing the retention time of peaks in the unknown samples with those of components of calibration standard mixtures. The importance of the physico-chemical properties and the significance of the fractional distillation and chromatographic separation methods to industrial process operations have been discussed.

  20. A Robust and Fully-Automated Chromatographic Method for the Quantitative Purification of Ca and Sr for Isotopic Analysis

    Science.gov (United States)

    Smith, H. B.; Kim, H.; Romaniello, S. J.; Field, P.; Anbar, A. D.

    2014-12-01

    High throughput methods for sample purification are required to effectively exploit new opportunities in the study of non-traditional stable isotopes. Many geochemical isotopic studies would benefit from larger data sets, but these are often impractical with manual drip chromatography techniques, which can be time-consuming and demand the attention of skilled laboratory staff. Here we present a new, fully-automated single-column method suitable for the purification of both Ca and Sr for stable and radiogenic isotopic analysis. The method can accommodate a wide variety of sample types, including carbonates, bones, and teeth; silicate rocks and sediments; fresh and marine waters; and biological samples such as blood and urine. Protocols for these isotopic analyses are being developed for use on the new prepFAST-MCTM system from Elemental Scientific (ESI). The system is highly adaptable and processes up to 24-60 samples per day by reusing a single chromatographic column. Efficient column cleaning between samples and an all Teflon flow path ensures that sample carryover is maintained at the level of background laboratory blanks typical for manual drip chromatography. This method is part of a family of new fully-automated chromatographic methods being developed to address many different isotopic systems including B, Ca, Fe, Cu, Zn, Sr, Cd, Pb, and U. These methods are designed to be rugged and transferrable, and to allow the preparation of large, diverse sample sets via a highly repeatable process with minimal effort.

  1. Simple and rapid gas-liquid-solid chromatographic analysis of trace concentrations of acetaldehyde in urban air.

    Science.gov (United States)

    Hoshika, Y

    1977-07-21

    A simple and rapid gas-liquid-solid chromatographic method for the analysis of trace concentrations of acetaldehyde in urban air (in the Nagoya area) was developed, with the use of cold trapping with liquid oxygen. In the analytical main column the conditions were: stationary phase, Triton X-100 (0.4%); support, Carbopack B (60-80 mesh); glass column, 1.5 m X 3 mm I.D.; column temperature, 75 degrees; carrier gas (nitrogen) flow-rate, 50-80 ml/min. In the cold trapping pre-column the conditions were: stationary phase, Tris (2-cyanoethoxy) propane (25%); support, Shimalite (AW, DMCS) (60-80 mesh); glass column, 31 cm X 4 mm I.D.; operating temperature for the trapping, -183 degrees (liquid oxygen temperature); operating temperature for injection of the condensed sample into the gas chromatograph, increased from -183 degrees to +100 degrees for 2 min. The acetaldehyde peak was identified by the disappearance method with a 2,4-dinitrophenylhydrazine-orthophosphoric acid-glass beads column. The ranges and average concentrations of acetaldehyde detected in 13 urban air samples were 1.5-9.6 and 4.7 ppb, respectively.

  2. Protein-bound carbohydrates in breast cancer. Liquid-chromatographic analysis for mannose, galactose, fucose, and sialic acid in serum.

    Science.gov (United States)

    Mrochek, J E; Dinsmore, S R; Tormey, D C; Waalkes, T P

    1976-09-01

    We describr high-resolution chromatographic analysis for protein-bound sialic acid in serum, with use of a cerate oxidimetric detector. Values for sera from normal women averaged 680.5 mg/liter, with a coefficient of variation of 23%. Including data obtained by previously developed chromatographic procedures for protein-bound mannose, galactose, and fucsoe, we assessed sera from breast-cancer patients whose malignancy had been categorized as either stable, responsive, or progressive (based on clinical observations spaced from two to five months apart). All of 12 responsive patients had decreases of protein-bound fucose averaging 34.5% (SD, 16.1) and all of 10 patients with progressive disease had increases averaging 38.3% (SD 21.5). Changes in fucose averaged less than 6.7% (SD, 4.9) for eight patients with clinically stable breast cancer. Changes in protein-bound mannose, galactose, and sialic acid did not correlate as well as did fucose with the clinical disease status of the patients.

  3. Protein-bound carbohydrates in breast cancer. Liquid-chromatographic analysis for mannose, galactose, fucose, and sialic acid in serum

    Energy Technology Data Exchange (ETDEWEB)

    Mrochek, J.E. (Oak Ridge National Lab., TN); Dinsmore, S.R.; Tormey, D.C.; Waalkes, T.P.

    1976-09-01

    High-resolution chromatographic analysis for protein-bound sialic acid in serum, with use of a cerate oxidimetric detector is described. Values for sera from normal women averaged 680.5 mg/liter, with a coefficient of variation of 23%. Including data obtained by previously developed chromatographic procedures for protein-bound mannose, galactose, and fucose, sera from breast-cancer patients whose malignancy had been categorized as either stable, responsive, or progressive (based on clinical observations spaced from two to five months apart) were assessed. All of 12 responsive patients had decreases of protein-bound fucose averaging 34.5% (SD, 16.1) and all of 10 patients with progressive disease had increases averaging 38.3% (SD 21.5). Changes in fucose averaged less than 6.7% (SD, 4.9) for eight patients with clinically stable breast cancer. Changes in protein-bound mannose, galactose, and sialic acid did not correlate as well as did fucose with the clinical disease status of the patients.

  4. Chromatographic analysis of some drugs employed in erectile dysfunction therapy: qualitative and quantitative studies using calixarene stationary phase.

    Science.gov (United States)

    Hashem, Hisham; Ibrahim, Adel Ehab; Elhenawee, Magda

    2014-10-01

    In this study, the effect of change in chromatographic process variables on the retention behavior of four drugs employed in erectile dysfunction therapy on a calixarene stationary phase is described. Three of these drugs are known to treat erectile dysfunction, namely, sildenafil citrate, tadalafil, and apomorphine hydrochloride, and one drug that is used as opioid analgesic, tramadol hydrochloride, which is quiet widely misused to treat premature ejaculation. The results indicate the importance of considering the structure and pKa values of drugs to be separated along with mobile phase composition. A new optimized, rapid, and accurate liquid chromatography method is also established for simultaneous determination of sildenafil citrate, tadalafil, and apomorphine hydrochloride in pharmaceutical preparations and bulk powders. The chromatographic separation of the three pharmaceuticals was achieved on a calixarene column in less than 10 min using a binary mobile phase of 35% acetonitrile and 65% 50 mM sodium perchlorate pH2.5 at 1 mL/min flow rate. The method was validated for system efficiency, linearity, accuracy, precision, limits of detection and quantitation, specificity, stability, and robustness. Statistical analysis proved that the method enabled reproducible and selective quantification of all three analytes in bulk drugs and in pharmaceutical preparations.

  5. [Chromatographic analysis of low molecular weight fraction of cerebrospinal fluid in children with acute neuroinfections].

    Science.gov (United States)

    Alekseeva, L A; Shatik, S V; Sorokina, M N; Karasev, V V

    2002-05-01

    Low molecular-weight (oligopeptide) fraction of the cerebrospinal fluid was analyzed by high-performance reversed phase liquid chromatography in 30 children with bacterial and viral neuroinfections. The incidence and height of chromathoraphic peaks in bacterial meningitis depended on the disease etiology, stage, and severity. Qualitative and quantitative composition of low molecular-weight fraction of the liquor varied in patients with viral neuroinfections, depending on the severity of the cerebral parenchyma involvement. Differences in chromatographic profiles in complicated and uneventful course of neuroinfections indicate a possible damaging, protective, or regulatory effect of the liquor peptides. These data focus the attention on the role of oligopeptides in the genesis of neuroinfectious process, significance of search for peptide markers, their further isolation, identification, and development of test systems available for clinical application.

  6. Validated stability-indicating high-performance thin-layer chromatographic method for estimation of cefpodoxime proxetil in bulk and in pharmaceutical formulation according to International conference on harmonization guidelines.

    Science.gov (United States)

    Jain, Pritam; Chaudhari, Amar; Bang, Anup; Surana, Sanjay

    2012-04-01

    A simple, selective, precise, and stability-indicating high-performance thin-layer chromatographic (HPTLC) method for analysis of cefpodoxime proxetil both in bulk and in pharmaceutical formulation has been developed and validated. The method employed HPTLC aluminum plates precoated with silica gel 60 RP-18 F(254) as the stationary phase. The solvent system consisted of toluene:methanol:chloroform (4:2:4 v/v). The system was found to give compact spot for cefpodoxime proxetil (R(f) value of 0.55 ± 0.02). Densitometric analysis of cefpodoxime proxetil was carried out in the absorbance mode at 289 nm. The linear regression analysis data for the calibration plots showed good linear relationship, with r(2) = 0.998 ± 0.0015 with respect to peak area in the concentration range of 100-600 ng per spot. The mean value±SD of slope and intercept were 3.38 ± 1.47 and 986.9 ± 108.78 with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 3.99 and 12.39 ng per spot, respectively. Cefpodoxime proxetil was subjected to acid and alkali hydrolysis, oxidation, and thermal degradation. The drug undergoes degradation under acidic and basic conditions, indicating that the drug is susceptible to both acid and base. The degraded product was well resolved from the pure drug, with significantly different R(f) value. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of the investigated drug. The proposed HPTLC method can be applied for identification and quantitative determination of cefpodoxime proxetil in both bulk drug and pharmaceutical formulation.

  7. Validated stability-indicating high-performance thin-layer chromatographic method for estimation of cefpodoxime proxetil in bulk and in pharmaceutical formulation according to International conference on harmonization guidelines

    Directory of Open Access Journals (Sweden)

    Pritam Jain

    2012-01-01

    Full Text Available Aim: A simple, selective, precise, and stability-indicating high-performance thin-layer chromatographic (HPTLC method for analysis of cefpodoxime proxetil both in bulk and in pharmaceutical formulation has been developed and validated. Materials and Methods: The method employed HPTLC aluminum plates precoated with silica gel 60 RP-18 F 254 as the stationary phase. The solvent system consisted of toluene:methanol:chloroform (4:2:4 v/v. The system was found to give compact spot for cefpodoxime proxetil (R f value of 0.55 ± 0.02. Densitometric analysis of cefpodoxime proxetil was carried out in the absorbance mode at 289 nm. Results: The linear regression analysis data for the calibration plots showed good linear relationship, with r 2 = 0.998 ± 0.0015 with respect to peak area in the concentration range of 100-600 ng per spot. The mean value±SD of slope and intercept were 3.38 ± 1.47 and 986.9 ± 108.78 with respect to peak area. The method was validated for precision, recovery, and robustness. The limits of detection and quantification were 3.99 and 12.39 ng per spot, respectively. Cefpodoxime proxetil was subjected to acid and alkali hydrolysis, oxidation, and thermal degradation. The drug undergoes degradation under acidic and basic conditions, indicating that the drug is susceptible to both acid and base. The degraded product was well resolved from the pure drug, with significantly different R f value. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of the investigated drug. Conclusion: The proposed HPTLC method can be applied for identification and quantitative determination of cefpodoxime proxetil in both bulk drug and pharmaceutical formulation.

  8. Assessing similarity analysis of chromatographic fingerprints of Cyclopia subternata extracts as potential screening tool for in vitro glucose utilisation.

    Science.gov (United States)

    Schulze, Alexandra E; De Beer, Dalene; Mazibuko, Sithandiwe E; Muller, Christo J F; Roux, Candice; Willenburg, Elize L; Nyunaï, Nyemb; Louw, Johan; Manley, Marena; Joubert, Elizabeth

    2016-01-01

    Similarity analysis of the phenolic fingerprints of a large number of aqueous extracts of Cyclopia subternata, obtained by high-performance liquid chromatography (HPLC), was evaluated as a potential tool to screen extracts for relative bioactivity. The assessment was based on the (dis)similarity of their fingerprints to that of a reference active extract of C. subternata, proven to enhance glucose uptake in vitro and in vivo. In vitro testing of extracts, selected as being most similar (n = 5; r ≥ 0.962) and most dissimilar (n = 5; r ≤ 0.688) to the reference active extract, showed that no clear pattern in terms of relative glucose uptake efficacy in C2C12 myocytes emerged, irrespective of the dose. Some of the most dissimilar extracts had higher glucose-lowering activity than the reference active extract. Principal component analysis revealed the major compounds responsible for the most variation within the chromatographic fingerprints, as mangiferin, isomangiferin, iriflophenone-3-C-β-D-glucoside-4-O-β-D-glucoside, iriflophenone-3-C-β-D-glucoside, scolymoside, and phloretin-3',5'-di-C-β-D-glucoside. Quantitative analysis of the selected extracts showed that the most dissimilar extracts contained the highest mangiferin and isomangiferin levels, whilst the most similar extracts had the highest scolymoside content. These compounds demonstrated similar glucose uptake efficacy in C2C12 myocytes. It can be concluded that (dis)similarity of chromatographic fingerprints of extracts of unknown activity to that of a proven bioactive extract does not necessarily translate to lower or higher bioactivity.

  9. Development and Validation of High Performance Thin-Layer Chromatographic Method for Determination of α-Mangostin in Fruit Pericarp of Mangosteen Plant (Garcinia mangostana L. using Ultraviolet – Visible Detection

    Directory of Open Access Journals (Sweden)

    Himanshu Misra

    2009-10-01

    Full Text Available A simple, fast and precise quantitative high performance thin-layer chromatographic method has been developed for quantitative estimation of α-mangostin in fruit pericarp of Garcinia mangostana L. (Hypericaceae. Best solvent for extraction of a-mangostin optimized after screening with five solvents under same conditions using hot solid-liquid extraction through soxhlet apparatus. Methanol and chloroform gave highest and second highest recovery of a-mangostin, respectively. Plates were developed in chloroform-methanol in the ratio of 27-3 (v/v. Post-chromatographic derivatization performed using anisaldehyde-sulphuric acid reagent and scanned at 382 nm in ultraviolet-visible mode. The developed method was found to be linear in the range 1.0 to 5.0 mg spot-1, limits of detection and quantitation were 150 and 450 ng spot-1. The developed method was validated in terms of system suitability, specificity and robustness.

  10. Gas-Chromatographic analysis of Mars soil samples with the SAM instrument onboard Curiosity - the 359 first sols

    Science.gov (United States)

    Szopa, Cyril; Navarro-Gonzalez, Rafael; Mahaffy, Paul; Buch, Arnaud; Goutail, Jean Pierre; Cabane, Michel; Glavin, Daniel; Correia, Jean-Jacques; Coll, Patrice; Freissinet, Caroline; Meftah, Mustapha; Coscia, David; Teinturier, Samuel; Brunner, Anna; Bonnet, Jean-Yves; Millan, Maeva; Pascalin

    Amongst the SAM suite of instruments, SAM-GC (Gas Chromatograph) is devoted to identify and quantify volatiles evolved from the thermal/chemical treatment of any soil sample collected by the Curiosity rover. The first soil samples analyzed with SAM were composed of windblown dust and sand collected at the Rocknest site, while the second site analyzed was a basin called “Yellowknife Bay” where two holes were drilled (John Klein & Cumberland) and analysis showed these sites to be a fluvio-lacustrine sediment.. For their analysis, these samples were subjected to a pyrolysis at temperatures reaching about 850°C. For SAM-GC and GCMS analyses, different fractions of pyrolysates were collected at different temperature in the ambient-900°C range in order to discriminate potential different volatile fractions present in the solid sample. With the aim to search for potential organic molecules outgassed from the samples, a SAM-GC analytical channel composed of a thermal-desorption injector and a MXT-CLP chromatographic column was used as it was designed for the separation of a wide range of volatile organic molecules. This channel is also equipped with a thermal conductivity detector (TCD) capable to detect the most abundant species (with abundances down to approximately 10-10mol). His channel is thus complementary to the mass spectrometer detection for quantification of such species, as this last instrument does not have linear response in this domain of high abundance, whereas it is significantly more sensitive than the TCD. The results obtained with this instrument first show that the performances of SAM-GC is representative of those obtained during calibrations of the instrument in laboratory, and also that results are repeatable. Hence, the instrument performs nominally, making it the first GCMS running successfully on Mars since the Viking missions (middle of the 70’s). Moreover, the complementarity of GC towards MS is also shown, both by allowing the

  11. Rapid process development of chromatographic process using direct analysis in real time mass spectrometry as a process analytical technology tool.

    Science.gov (United States)

    Yan, Binjun; Chen, Teng; Xu, Zhilin; Qu, Haibin

    2014-06-01

    The concept of quality by design (QbD) is widely applied in the process development of pharmaceuticals. However, the additional cost and time have caused some resistance about QbD implementation. To show a possible solution, this work proposed a rapid process development method, which used direct analysis in real time mass spectrometry (DART-MS) as a process analytical technology (PAT) tool for studying the chromatographic process of Ginkgo biloba L., as an example. The breakthrough curves were fast determined by DART-MS at-line. A high correlation coefficient of 0.9520 was found between the concentrations of ginkgolide A determined by DART-MS and HPLC. Based on the PAT tool, the impacts of process parameters on the adsorption capacity were discovered rapidly, which showed a decreased adsorption capacity with the increase of the flow rate. This work has shown the feasibility and advantages of integrating PAT into QbD implementation for rapid process development.

  12. Vegetative anatomy and micromorphology of Salvia divinorum (Lamiaceae) from Mexico, combined with chromatographic analysis of salvinorin A.

    Science.gov (United States)

    Kowalczuk, Anna P; Raman, Vijayasankar; Galal, Ahmed M; Khan, Ikhlas A; Siebert, Daniel J; Zjawiony, Jordan K

    2014-01-01

    Salvia divinorum--a species traditionally cultivated in Oaxaca, Mexico--possesses hallucinogenic properties. It is legally recognized as a controlled substance and prohibited in many countries. The proper identification of the plant, both in fresh and dried forms, is an important issue in crime-prevention campaigns. This paper provides a thorough anatomical description of leaves, petioles, and stems of S. divinorum. Detailed investigation of foliar trichomes was performed and illustrated. In addition, chromatographic analyses, including TLC and HPLC, were applied to fresh and dried plant material, together with the standard reference salvinorin A. A comprehensive identification method for S. divinorum based on a thorough anatomical examination is proposed, combined with chemical analysis for proper plant recognition.

  13. An improved liquid chromatographic method for the analysis of tylosin and its impurities.

    Science.gov (United States)

    Ashenafi, Dunge; Hoogmartens, Jos; Adams, Erwin

    2011-10-01

    A selective reversed-phase (RP) liquid chromatographic (LC) method coupled with UV for the determination of tylosin and its related substances is described. The gradient method uses a Capcell pak C18 ACR column (25 cm×4.6 mm id, 5 μm) maintained at a temperature of 60°C. The mobile phases consist of acetonitrile, phosphate buffer pH 5.5 and water: (A; 27.5:10:62.5 v/v/v) and (B; 50:10:40 v/v/v). The flow rate is 1.0 mL/min and UV detection is performed at 280 nm. It allows the separation of all known and 22 other unknown related substances (≥0.02%) from the main compound and from one another. The method shows good precision, sensitivity, linearity (between 0.2 μg/mL and 1.25 mg/mL) and robustness. The limit of quantification is 0.2 μg/mL, corresponding to 0.020%. Seven bulk tylosin samples containing a large number of impurities were examined using this method. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Capillary gas chromatographic analysis of nerve agents using large volume injections. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Deinum, T.; Nieuwenhuy, C.

    1994-11-01

    The procedure developed at TNO-Prins Maurits Laboratory (TNO-PML) for the verification of intact organophosphorus chemical warfare agents in water samples was improved. The last step in this procedure, the laborious and non-reproducible transfer of an ethyl acetate extract onto a Tenax-adsorption tube followed by thermal desorption of the Tenax-tube, was replaced by large volume injection of the extract onto a capillary gas chromatographic system. The parameters controlling the injection of a large volume of an extract (200 ul) were investigated and optimized. As ethyl acetate caused severe problems, potential new solvents were evaluated. With the improved procedure, the nerve agents sarin, tabun, soman, diisopropyl fluorophosphate (DFP) and VX could be determined in freshly prepared water samples at pg/ml (ppt) levels. The fate of the nerve agents under study in water at two pH`s (4.8 and 6) was investigated. For VX, the pH should be adjusted before extraction. Moreover, it is worthwhile to acidify water samples to diminish hydrolysis.

  15. High Performance Liquid Chromatographic Analysis of Almotriptan Malate in Bulk and Tablets

    Directory of Open Access Journals (Sweden)

    Chandra Bala Sekaran

    2013-02-01

    Full Text Available Purpose: A simple RP-HPLC method has been developed and validated for the determination of almotriptan malate (ATM in bulk and tablets. Methods: Chromatographic separation of ATM was achieved by using a Thermo Scientific C18 column. A Mobile phase containing a mixture of methanol, water and acetic acid (4:8:0.1 v/v was pumped at the flow rate of 1 mL/min. Detection was performed at 227 nm. According to ICH guidelines, the method was validated. Results: The calibration curve was linear in the concentration range 5–60 μg/mL for the ATM with regression coefficient 0.9999. The method was precise with RSD <1.2%. Excellent recoveries of 99.60 - 100.80% proved the accuracy of the method. The limits of detection and quantification were found to be 0.025 and 0.075 μg/mL, respectively. Conclusion: The method was successfully applied for the quantification of ATM in tablets with acceptable accuracy and precision.

  16. Development and validation of high performance liquid chromatographic method for analysis of clozapine.

    Science.gov (United States)

    Kaur, Harpreet; Bassi, Pallavi; Monif, Tausif; Khuroo, Arshad; Kaur, Gurpreet

    2013-05-01

    In this study a rapid, simple and sensitive assay to quantify clozapine in human plasma by using reverse phase high performance liquid chromatographic method has been developed. Clozapine was extracted from human plasma using a mixture of chloroform: n-hexane 50:50 employing liquid-liquid extraction method. The calibration curve was found to be linear in the concentration range of 25-800 ng/ml. The inter day and intra day assay accuracy and precision fulfilled the criteria specified by USFDA, Guidance for industry: bioanalytical method validation. Clozapine was found to be stable in human plasma after 6 h incubation at room temperature, 50 days storage at -27°C and freeze thaw cycles, as well as after reconstitution with mobile phase after 24 h of storage in refrigerator. The validated method offers the advantage of using minimum injection volume (25μl) and plasma sample volume (300μl). The extraction method is simple and single step with no back extraction step, thus, making this method applicable to determination of pharmacokinetic profiles and parameters.

  17. Integrated Analysis of the Wood Oil from Xanthocyparis vietnamensis Farjon & Hiep. by Chromatographic and Spectroscopic Techniques

    Directory of Open Access Journals (Sweden)

    Ophélie Bazzali

    2016-06-01

    Full Text Available In order to get better knowledge about the volatiles produced by Xanthocyparis vietnamensis, a species recently discovered in Vietnam, its wood oil has been analyzed by a combination of chromatographic (GC, CC and spectroscopic (GC-MS, 13C-NMR techniques. Forty components that accounted for 87.9% of the oil composition have been identified. The composition is dominated by nootkatene (20.7%, 11,12,13-tri-nor-eremophil-1(10-en-7-one (17.2%, γ-eudesmol (5.1%, nootkatone (4.7%, valencene (3.5% and 13-nor-eremophil-1(10-en-11-one (2.6%. The structure of two new compounds—10-epi-nor-γ-eudesmen-11-one and 12-hydroxy-isodihydroagarofuran—has been elucidated, while 11,12,13-tri-nor-eremophil-1(10-en-7-ol is reported as a natural product for the first time. The composition of X. vietnamensis wood oil varied drastically from those of leaf oils, dominated by hedycaryol (34.4%, phyllocladene (37.8% or by pimara-6(14-15-diene (19.4%.

  18. Purge and trap with monolithic sorbent for gas chromatographic analysis of pesticides in honey.

    Science.gov (United States)

    Chienthavorn, Orapin; Dararuang, Kanittha; Sasook, Anupop; Ramnut, Narumol

    2012-01-01

    Polydivinylbenzene (P-DVB) and silica monolithic materials were synthesised in capillaries and then used to adsorb nine organonitrogen pesticides extracted from honey. After adsorption, each monolith-capillary was connected to a gas chromatograph (GC) with nitrogen-phosphorous detector (NPD). The silica monolith gave better peak shape and intensity than the P-DVB monolith. Formulation of silica monolith with tetramethoxysilane (TMOS) as a sole initiator provided better separation and higher peak intensity, compared to those with methyltrimethoxysilane (MTMS) and (3:1) TMOS/MTMS initiators. The optimum internal diameter and length of silica monolith-capillary were 0.25 mm and 5 cm, respectively. The purge and trap conditions were optimised by purging with nitrogen and heating the honey sample solution at 100 °C for 60 min. Recovery of the method was in a range of 84.95-99.71% and the detection limits of the pesticides determined by using GC-NPD and GC-mass spectrometric detector (MSD) ranged between 0.36-1.75 and 0.13-0.25 ng g(-1), respectively.

  19. Hydroxypyridyl Imines: Enhancing Chromatographic Separation and Stereochemical Analysis of Chiral Amines via Circular Dichroism.

    Science.gov (United States)

    Joyce, Leo A; Regalado, Erik L; Welch, Christopher J

    2016-09-16

    Imine-bond formation between chiral amines and commercially available 3-hydroxypyridine-2-carboxaldehyde (HCA) was exploited for rapid determination of stereochemical composition. Chiral supercritical fluid chromatography (SFC) screening of the derivatized imine compounds led to the elucidation of multiple combinations of mobile and stationary phases that gave resolution of all members of a series of chiral amines. The first eluting enantiomer was generally the derivative of the (R)-amine enantiomer across the series that was studied, indicating that the imine formed from the (S)-amine has more favorable interaction with the chiral stationary phase of the column. These conditions were then applied to more challenging compounds, namely amino alcohols and diastereomers possessing more than one stereocenter. The approach was utilized to monitor stereoselective biocatalytic transamination and assign the absolute configuration of the enantiomeric products. Finally, hydrolysis of the imine bond of the derivative was shown to generate enantiopure amine starting materials without racemization. This further highlights the value of this approach for creating readily reversed derivatives that enhance chromatographic separation and aid in the determination of absolute configuration.

  20. Integrated Analysis of the Wood Oil from Xanthocyparis vietnamensis Farjon & Hiep. by Chromatographic and Spectroscopic Techniques.

    Science.gov (United States)

    Bazzali, Ophélie; Thai, Tran Huy; Hoi, Tran Minh; Khang, Nguyen Sinh; Hien, Nguyen Thi; Casanova, Joseph; Bighelli, Ange; Tomi, Félix

    2016-06-27

    In order to get better knowledge about the volatiles produced by Xanthocyparis vietnamensis, a species recently discovered in Vietnam, its wood oil has been analyzed by a combination of chromatographic (GC, CC) and spectroscopic (GC-MS, (13)C-NMR) techniques. Forty components that accounted for 87.9% of the oil composition have been identified. The composition is dominated by nootkatene (20.7%), 11,12,13-tri-nor-eremophil-1(10)-en-7-one (17.2%), γ-eudesmol (5.1%), nootkatone (4.7%), valencene (3.5%) and 13-nor-eremophil-1(10)-en-11-one (2.6%). The structure of two new compounds-10-epi-nor-γ-eudesmen-11-one and 12-hydroxy-isodihydroagarofuran-has been elucidated, while 11,12,13-tri-nor-eremophil-1(10)-en-7-ol is reported as a natural product for the first time. The composition of X. vietnamensis wood oil varied drastically from those of leaf oils, dominated by hedycaryol (34.4%), phyllocladene (37.8%) or by pimara-6(14)-15-diene (19.4%).

  1. Improved simultaneous gas-chromatographic analysis for homovanillic acid and vanillylmandelic acid in urine.

    Science.gov (United States)

    Leiendecker-Foster, C; Freier, E F

    1981-12-01

    We describe an improved gas-chromatographic method for the simultaneous quantitation of the catecholamine metabolites, homovanillic acid (3-methoxy-4-hydroxyphenylacetic acid) and vanillylmandelic acid (3-methoxy-4-hydroxymandelic acid). Our improvements in the method of Muskiet et al. (Clin. Chem. 23: 863, 1977) include a shorter program time and a longer silylation interval. Recovery and precision data obtained by this improved technique are similar to those of Muskiet et al. Vanillylmandelic acid results (y) were compared with those by the method of Pisano et al. (Clin. Chim. Acta 7: 285, 1962). The relation is expressed by the equation y = 0.52 + 1.05x (Sy . x = 2.33 mg/24 h and r = 0.997). Results for homovanillic acid (y) were compared with those by the method of Knight and Haymond (Clin. Chem. 23: 2007, 1977); the equation was y = 0.84 + 0.90x (Sy . x = 2.04 and r = 0.97). Retention times are also reported for several phenolic acids and other related compounds found in urine.

  2. Survey For Detection and Determination of Aflatoxins M1 and B1 in local Milk and Certain Dairy Products by Thin Layer Chromatographic Method

    Directory of Open Access Journals (Sweden)

    T.A. Nassib *,S.N. Guergues** , M.M. Motawee

    2005-03-01

    Full Text Available 90 different type of milk samples, 10 Yogurt Samples, 110 different type of cheese samples and 10 ice cream samples were collected randomly from Giza Governorate during the summer of 1998 ­ 1999, for detection and determination of Aflatoxins M1& B1 by using thin layer chromatographic method. Results revealed that the average range of Aflatoxin M1 in milk samples amounted from 0.144 to 0.378 ng/ml. About 20 % of cows and buffaloes milk samples contained form 0.378 to 0.342 ng/ml of AFM1, whereas about 10% of other milk samples were contaminated with 0.162, 0.288, 0.324, 0.234, 0.144 and 0.162 ng/ml for skim , Pasteurized , sterilized, UHT, powder, and baby milk, in the same order. Concentrations of AFM1 detected in cheese samples, furthermore, varied due to the type and age of cheese being examined. 20% of cheese samples were contaminated with AFM1 being 5.1, 3.2, 2.99, 2.099, and 2.34 ng/gm for fresh Domiati, aged Domiati, Processed and Karish cheese, respectively, whereas, 30% of the other types of cheese contained 5.88, 6.3 and 3.4 ng/gm for Roquefort, fresh Romi, and Cheddar cheese, respectively. The lowest concentration of AFM1, of 0.116 ng/gm was detected, however, in 10% of yogurt samples. Meanwhile, 20% of ice cream samples were found to be contaminated with 2.7 ng/ml, and 10% of Feta cheese samples contained 3.3 ng/gm. It could also be appeared from results that both of cream and spread cheese were found completely free from this Aflatoxin, the lowest content of Aflatoxin detected in all of the above examined samples was 0.116, 0.162, 0.162 and 0.216 (ppb in yogurt, skim, baby milk and cream, respectively. On the other hand, results also indicated that all milk samples were free from Aflatoxin B1 except one sample of skim milk (out of 10 which gave positive result.

  3. Characterization of Gas Chromatographic Liquid Phases Using McReynolds Constants. An Experiment for Instrumental Analysis Laboratory.

    Science.gov (United States)

    Erskine, Steven R.; And Others

    1986-01-01

    Describes a laboratory experiment that is designed to aid in the understanding of the fundamental process involved in gas chromatographic separations. Introduces the Kovats retention index system for use by chemistry students to establish criteria for the optimal selection of gas chromatographic stationary phases. (TW)

  4. Chromatographic analysis of age-related changes in mucosal serotonin transmission in the murine distal ileum

    Directory of Open Access Journals (Sweden)

    Parmar Leena

    2012-04-01

    Full Text Available Abstract Background In the upper bowel, alterations in motility and absorption of key nutrients have been observed as part of the normal ageing process. Serotonin (5-HT is a key signalling molecule in the gastrointestinal tract and is known to influence motility, however little is known of how the ageing process alters 5-HT signalling processes in the bowel. Results An isocratic chromatographic method was able to detect all 5-HT precursors and metabolites. Using extracellular and intracellular sampling approaches, we were able to monitor all key parameters associated with the transmission process. There was no alteration in the levels of tryptophan and 5-HTP between 3 and 18 month old animals. There was a significant increase in the ratio of 5-HT:5-HTP and an increase in intracellular 5-HT between 3 and 18 month old animals suggesting an increase in 5-HT synthesis. There was also a significant increase in extracellular 5-HT with age, suggesting increased 5-HT release. There was an age-related decrease in the ratio of intracellular 5-HIAA:extracellular 5-HT, whilst the amount of 5-HIAA did not change with age. In the presence of an increase in extracellular 5-HT, the lack of an age-related change in 5-HIAA is suggestive of a decrease in re-uptake via the serotonin transporter (SERT. Conclusions We have used intracellular and extracellular sampling to provide more insight into alterations in the neurotransmission process of 5-HT during normal ageing. We observed elevated 5-HT synthesis and release and a possible decrease in the activity of SERT. Taken together these changes lead to increased 5-HT availability and may alter motility function and could lead to the changes in adsorption observed in the elderly.

  5. Portfolio analysis of layered security measures.

    Science.gov (United States)

    Chatterjee, Samrat; Hora, Stephen C; Rosoff, Heather

    2015-03-01

    Layered defenses are necessary for protecting the public from terrorist attacks. Designing a system of such defensive measures requires consideration of the interaction of these countermeasures. In this article, we present an analysis of a layered security system within the lower Manhattan area. It shows how portfolios of security measures can be evaluated through portfolio decision analysis. Consideration is given to the total benefits and costs of the system. Portfolio diagrams are created that help communicate alternatives among stakeholders who have differing views on the tradeoffs between security and economic activity.

  6. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

    DEFF Research Database (Denmark)

    Larsen, Kirsten Kolbjørn; Wielandt, Daniel Kim Peel; Schiller, Martin;

    2016-01-01

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of ...

  7. Chromatographic analysis on trace amount harmful substance in water%水环境中痕量有害物质色谱分析

    Institute of Scientific and Technical Information of China (English)

    孙鹏; 李伟娟

    2015-01-01

    This article describes the chromatographic analysis on trace amount harmful substance in terms of current state and features of water environment.%文章针对水环境的现状以及特点,对其中痕量有害物质进行了系统的色谱分析.

  8. Gas chromatographic-mass spectrometric analysis of steroids and steroid glucuronides in the seminal vesicle fluid of the African catfish, Clarias gariepinus

    NARCIS (Netherlands)

    Schoonen, W.G.E.J.; Lambert, J.G.D.

    1987-01-01

    Gas chromatographic-mass spectrometric analysis was carried out to identify steroids and steroid glucuronides in the seminal vesicle fluid of African catfish, Clarias gariepinus, collected in the Hula nature reserve (Israel) during the breeding season. Full mass spectra of 5β-pregnane-3α,17α-diol-20

  9. AN OVERVIEW ON THE STANDARDIZATION OF CHROMATOGRAPHIC METHODS FOR SCREENING ANALYSIS IN TOXICOLOGY BY MEANS OF RETENTION INDEXES AND SECONDARY STANDARDS .1. GAS-CHROMATOGRAPHY

    NARCIS (Netherlands)

    FRANKE, JP; BOGUSZ, M; DEZEEUW, RA

    1993-01-01

    In systematic toxicological analysis, in which a logical analytical search for a potentially harmful substance has to be carried out, chromatographic methods are of utmost importance since the retention parameter can be used for primary identification. In gas chromatography the Kovats retention

  10. Decoding glycome of Astragalus membranaceus based on pressurized liquid extraction, microwave-assisted hydrolysis and chromatographic analysis.

    Science.gov (United States)

    Lv, G P; Hu, D J; Cheong, K L; Li, Z Y; Qing, X M; Zhao, J; Li, S P

    2015-08-28

    Carbohydrates in herbs are a relatively untapped source of new drugs and health beneficial ingredients. Their analysis has been developed as a novel aspect in quality control and herbal glycomics. In this study, glycome of Astragalus membranaceus was decoded based on optimized pressurized liquid extraction (PLE), microwave-assisted acidic hydrolysis (MAAH) and comprehensive chromatographic approaches. Twelve saccharides including sucrose, galacturonic acid, mannitol, fructose, rhamnose, ribose, arabinose, fucose, xylose, mannose, glucose and galactose were quantitatively analyzed by GC-MS and HPLC-CAD (charged aerosol detectors). Different columns, including Prevail Carbohydrate ES, XBridge Amide and CARBOSep CHO-820 CA for HPLC-CAD analysis, were compared for evaluation of oligosaccharides. The polysaccharides in water extract of Astragalus membranaceus were characterized by high performance size exclusive chromatography (HPSEC) combined with multiple angle light scattering detection (MALSD) and refractive index detection (RID). The results showed that A. membranaceus contained more than 108.5mgg(-1) free sucrose and small amounts of glucose 9.6-26.0mgg(-1) and fructose 8.7-22.9mgg(-1). While its polymeric carbohydrates were composed of glucose 71.0-162.3mgg(-1), galacturonic acid 52.0-113.4mgg(-1), arabinose 22.8-54.4mgg(-1) and small amounts of galactose, rhamnose, xylose and mannose. CARBOSep CHO-820 CA showed its potential in simultaneously analyzing oligosaccharides and uronic acid, especially only the environment-friendly water mobile phase was used. HPSEC-MALSD-RID showed that there were three different molecular weight distributions of polysaccharides in A. membranaceus and the average molecular weight were 21901.1, 2038.5, and 353.4kDa. Hierarchical clustering analysis and principal component analysis demonstrated that A. membranaceus from different regions showed variations both in free and polymeric carbohydrates, which indicated that carbohydrates

  11. Characterization of Chinese rice wine taste attributes using liquid chromatographic analysis, sensory evaluation, and an electronic tongue.

    Science.gov (United States)

    Yu, HaiYan; Zhao, Jie; Li, Fenghua; Tian, Huaixiang; Ma, Xia

    2015-08-01

    To evaluate the taste characteristics of Chinese rice wine, wine samples sourced from different vintage years were analyzed using liquid chromatographic analysis, sensory evaluation, and an electronic tongue. Six organic acids and seventeen amino acids were measured using high performance liquid chromatography (HPLC). Five monosaccharides were measured using anion-exchange chromatography. The global taste attributes were analyzed using an electronic tongue (E-tongue). The correlations between the 28 taste-active compounds and the sensory attributes, and the correlations between the E-tongue response and the sensory attributes were established via partial least square discriminant analysis (PLSDA). E-tongue response data combined with linear discriminant analysis (LDA) were used to discriminate the Chinese rice wine samples sourced from different vintage years. Sensory evaluation indicated significant differences in the Chinese rice wine samples sourced from 2003, 2005, 2008, and 2010 vintage years in the sensory attributes of harmony and mellow. The PLSDA model for the taste-active compounds and the sensory attributes showed that proline, fucose, arabinose, lactic acid, glutamic acid, arginine, isoleucine, valine, threonine, and lysine had an influence on the taste characteristic of Chinese rice wine. The Chinese rice wine samples were all correctly classified using the E-tongue and LDA. The electronic tongue was an effective tool for rapid discrimination of Chinese rice wine.

  12. Gas purge microsyringe extraction for quantitative direct gas chromatographic-mass spectrometric analysis of volatile and semivolatile chemicals.

    Science.gov (United States)

    Yang, Cui; Piao, Xiangfan; Qiu, Jinxue; Wang, Xiaoping; Ren, Chunyan; Li, Donghao

    2011-03-25

    Sample pretreatment before chromatographic analysis is the most time consuming and error prone part of analytical procedures, yet it is a key factor in the final success of the analysis. A quantitative and fast liquid phase microextraction technique termed as gas purge microsyringe extraction (GP-MSE) has been developed for simultaneous direct gas chromatography-mass spectrometry (GC-MS) analysis of volatile and semivolatile chemicals without cleanup process. Use of a gas flowing system, temperature control and a conventional microsyringe greatly increased the surface area of the liquid phase micro solvent, and led to quantitative recoveries of both volatile and semivolatile chemicals within short extraction time of only 2 min. Recoveries of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and alkylphenols (APs) determined were 85-107%, and reproducibility was between 2.8% and 8.5%. In particular, the technique shows high sensitivity for semivolatile chemicals which is difficult to achieve in other sample pretreatment techniques such as headspace-liquid phase microextraction. The variables affecting extraction efficiency such as gas flow rate, extraction time, extracting solvent type, temperature of sample and extracting solvent were investigated. Finally, the technique was evaluated to determine PAHs, APs and OCPs from plant and soil samples. The experimental results demonstrated that the technique is economic, sensitive to both volatile and semivolatile chemicals, is fast, simple to operate, and allows quantitative extraction. On-site monitoring of volatile and semivolatile chemicals is now possible using this technique due to the simplification and speed of sample treatment.

  13. Qualitative analysis of Cu2+, Co2+, and Ni2+ cations using thin-layer chromatography.

    Science.gov (United States)

    Ergül, Soner

    2004-03-01

    The M(DEDTC)2 (M = Cu, Co, or Ni) and M(PyDTC)2 (M = Cu or Co) complexes prepared by reactions of sodium diethyldithiocarbamate and ammonium pyrollidinedithiocarbamate with metal (II) nitrates are examined for qualitative analysis and separation using thin-layer chromatography systems. These complexes and their mixtures are spotted to the activated thin layers of silica gel 60GF254 (Si-60GF254) with a 250-microm thickness. Pure toluene and a toluene-cyclohexane mixture (3:1, v/v) are used as mobile phases for running of the complexes. These chromatographic systems are successfully used for qualitative analysis of corresponding metal cations and separation of components in both M(DEDTC)2 and M(PyDTC)2 complex mixtures.

  14. Use of moment of inertia in comparative molecular field analysis to model chromatographic retention of nonpolar solutes.

    Science.gov (United States)

    Collantes, E R; Tong, W; Weish, W J; Zielinski, W L

    1996-07-01

    A quantitative structure-retention relationship (QSRR) was developed from chromatographic data on 31 unsubstituted 3-6 ring polycyclic aromatic hydrocarbons (PAHs) using the 3D-QSAR method known as comparative molecular field analysis (CoMFA). The resulting CoMFA model gave an excellent correlation to high-performance liquid chromatography retention data for these PAHs yielding r2 values of 0.947 (conventional) and 0.865 (cross-validated). The steric and electrostatic contributions to the CoMFA model were 100% and 0%, respectively. A unique feature of this study was the use of moment of inertia, I, as a basis for CoMFA alignment of the PAH molecules. The moment of inertia also provided an alternative method for calculating the solute length-to-breadth ratio (L/B), which has been applied in previous QSRR studies as a molecular descriptor for PAH retention. By virtue of its mathematical simplicity and lack of ambiguity, the present derivation of L/B from I offers several advantages over other geometry-based schemes. Finally, Ix was evaluated for use as a molecular descriptor in QSRR regression analysis to predict the log of the retention index (log I) for these PAHs. The correlation with PAH retention was weak when the moment of inertia was considered alone but improved dramatically (r2 = 0.928) when the moment of inertia and connectivity index chi were used in combination as descriptors.

  15. Interlaboratory tests to identify irradiation treatment of various foods via gas chromatographic detection of hydrocarbons, ESR spectroscopy and TL analysis

    Energy Technology Data Exchange (ETDEWEB)

    Schreiber, G.A.; Helle, N.; Schulzki, G.; Linke, B.; Spiegelberg, A.; Mager, M.; Boegl, K.W. [BgVV - Federal Inst. for Health Protection of Consumers and Veterinary Medicine, Berlin (Germany)

    1996-12-31

    The gas chromatographic (GC) analysis of radiation-induced volatile hydrocarbons (HC) and 2-alkylcyclobutanones, the ESR spectroscopic detection of radiation-specific radicals and the thermoluminescence (TL) analysis of silicate mineral are the most important methods for identification of irradiated foods. After successful performance in interlaboratory studies on meat products, fish, spices, herbs and shells of nuts, all or some of these methods have been approved by national authorities in Germany and the United Kingdom. Recently, draft European Standards have been elaborated for approval by member states of the European Committee for Standardization (CEN). Several research laboratories have shown that these methods can be applied to various foods not yet tested in collaborative studies. However, for an effective application in food control it is necessary to prove their suitability in interlaboratory studies. Therefore, in 1993/94, various interlaboratory tests were organised by the BgVV. In an ESR spectroscopic test, shrimps and paprika powder were examined. Shrimps were also the subject of examination in a TL test. Finally, GC detection of radiation-induced hydrocarbons in the fat fraction of foods was used in another test to identify irradiated Camembert, avocado, papaya and mango. In the following paper, results of the interlaboratory tests are summarised. Detailed reports are published by this institute. (author).

  16. Fast gas chromatographic residue analysis in animal feed using split injection and atmospheric pressure chemical ionisation tandem mass spectrometry.

    Science.gov (United States)

    Tienstra, M; Portolés, T; Hernández, F; Mol, J G J

    2015-11-27

    Significant speed improvement for instrumental runtime would make GC–MS much more attractive for determination of pesticides and contaminants and as complementary technique to LC–MS. This was the trigger to develop a fast method (time between injections less than 10 min) for the determination of pesticides and PCBs that are not (or less) amenable to LC–MS. A key factor in achieving shorter analysis time was the use of split injection (1:10) which allowed the use of a much higher initial GC oven temperature. A shorter column (15 m), higher temperature ramp, and higher carrier gas flow rate (6 mL/min) further contributed to analysis-time reduction. Chromatographic resolution was slightly compromised but still well fit-for-purpose. Due to the high sensitivity of the technique used (GC–APCI-triple quadrupole MS/MS), quantification and identification were still possible down to the 10 μg/kg level, which was demonstrated by successful validation of the method for complex feed matrices according to EU guidelines. Other advantages of the method included a better compatibility of acetonitrile extracts (e.g. QuEChERS) with GC, and a reduced transfer of co-extractants into the GC column and mass spectrometer.

  17. Chromatographic fingerprint analysis and simultaneous determination of eight lignans in Justicia procumbens and its compound preparation by HPLC-DAD.

    Science.gov (United States)

    Wang, Linan; Pan, Jianyu; Yang, Meihua; Wu, Jun; Yang, Junshan

    2011-03-01

    HPLC fingerprints were developed for the quality evaluation of Justicia procumbens and its compound preparation, Jian-er syrup, together with the simultaneous quantification of eight arylnaphthalide lignans (6'-hydroxy justicidin B, 6'-hydroxy justicidin A, 6'-hydroxy justicidin C, justicidin B, chinensinaphthol methyl ether, justicidin C, taiwanin C, and neojusticin A). Samples were separated with a Shiseido Capcell Pak C(18) reversed-phase column (250×4.6 mm id, 5 μm) using acetonitrile and water as the mobile phase. The column temperature was maintained at 35°C and the wavelength of detector was set at 256 nm. For fingerprint analysis, 17 peaks were selected as the characteristic peaks for the evaluation of the similarities among different J. procumbens samples collected in different places. The structures of lignans were confirmed by diagnostic fragments in the positive ESI-MS(n) . The new method was successfully applied for the chromatographic fingerprint analysis and simultaneous determination of eight lignans in its compound preparation, Jian-er syrup. All the results indicated that HPLC fingerprint assay in combination with multi-marker determination afforded a useful method for the quality control of J. procumbens and its compound preparation, Jian-er syrup.

  18. Reverse-phase high pressure liquid chromatographic analysis of harpagoside, scorodioside and verbascoside from Scrophularia scorodonia: quantitative determination of harpagoside.

    Science.gov (United States)

    Díaz, A; Fernández, L; Ollivier, E; Martín, T; Villaescusa, L; Balansard, G

    1998-02-01

    A reversed-phase high performance liquid chromatographic method has been developed for the determination of the main compounds (harpagoside, scorodioside, and verbascoside) from different samples of Scrophularia scorodonia. The chromatographic method has been validated and applied for quantitative determination of harpagoside. The results show the highest levels of harpagoside in the leaf extract. The purity and identity of peaks were controlled by diode-array detection and comparison with standards.

  19. Qualitative assessment of IC50 values of inhibitors of the neuronal nicotinic acetylcholine receptor using a single chromatographic experiment and multivariate cluster analysis.

    Science.gov (United States)

    Jozwiak, Krzysztof; Moaddel, Ruin; Yamaguchi, Rika; Ravichandran, Sarangan; Collins, Jack R; Wainer, Irving W

    2005-05-05

    It has been widely demonstrated that affinity chromatography can be used to derive binding affinities, and that these affinities can be correlated to data obtained using standard techniques such as membrane binding, ultrafiltration and equilibrium dialysis. The purpose of this study is to evaluate the use of immobilized nicotinic acetylcholine receptor stationary phase in chromatographic experiments to assess the functional activity of series of noncompetitive inhibitors (NCIs) as reflected in their IC50 values. Chromatographically determined retention values and computer generated molecular descriptors were obtained for 29 compounds and the data were analyzed by cluster analysis. The approach qualitatively ranked the test compounds as efficient NCIs (low IC50 values) or poor NCIs (high IC50 values). The data obtained with the 29 compounds used in this study demonstrate that the experimental approach had been able to place 25 of these compounds in the correct IC(50) clusters. To our knowledge, this is the first relationship established between chromatographic retention and IC50 for membrane-bound receptors. These results suggest that the chromatographic approach may be useful in development of lead drug candidates including the determination of off-target binding.

  20. Chromatographic analysis of phenol compounds in six natural populations of Anthyllis vulneraria (L.

    Directory of Open Access Journals (Sweden)

    Andzrej Kalinowski

    2015-01-01

    Full Text Available Thin-layer chromatography was used to study the phenol composition in individual plants from six natural populations of Anthyllis collected from three distinct geographic regions of Poland. The results showed a variability of the phenols in the examined populations. The populations from Wielkopolska region proved to be most variable, showing the greatest number of phenols. The lowest number of the phenols studies was found in the Tatry populations. Each population showed its own particular spectrum of phenolic compounds. It was found that the populations originating from similar habitats showed more common spots than those from different regions. Populations from the Tatra region were found to differ most from the rest.

  1. An SEC/MALS Study of Alternan Degradation During Size-exclusion Chromatographic Analysis

    Science.gov (United States)

    The degradation of high molar mass polymers during size-exclusion chromatography (SEC) analysis has been a topic of interest for several decades. Should a polymer degrade during analysis, the accuracy of the molar mass (M) and architectural information obtained will be compromised. To this effect,...

  2. Microwave-Assisted Extraction Followed by Solid-Phase Extraction for the Chromatographic Analysis of Alkaloids in Stephania cepharantha.

    Science.gov (United States)

    Liu, Ying; Xie, Daotao; Kang, Yun; Wang, Yaqin; Yang, Ping; Guo, Jixian; Huang, Jianming

    2016-04-01

    A procedure involving microwave-assisted extraction (MAE) followed by solid-phase extraction (SPE) was established for the extraction and purification of three bisbenzylisoquinoline alkaloids from Stephania cepharantha, and a reversed-phase high-performance liquid chromatography (HPLC) method was developed for the quantification of the target alkaloids. Chromatographic separation was achieved on a Phenomenex Luna Phenyl-Hexyl column. Prior to the HPLC analysis, the alkaloids were rapidly extracted by an optimized MAE process using 0.01 mol/L hydrochloric acid as the solvent. The MAE extract was subsequently purified by SPE using a cation-exchange polymeric cartridge. The MAE-SPE procedure extracted the three alkaloids with satisfactory recoveries ranging from 100.44 to 102.12%. In comparison with the MAE, Soxhlet and ultrasonic-assisted extractions, the proposed MAE-SPE method showed satisfactory cleanup efficiency. Thus, the validated MAE-SPE-HPLC method is specific, accurate and applicable to the determination of alkaloids in S. cepharantha.

  3. Quantitative Mass spectrometric Analysis of Ropivacaine and Bupivacaine in Authentic, Pharmaceutical and Spiked Human Plasma without Chromatographic Separation

    Directory of Open Access Journals (Sweden)

    Nahla N. Salama

    2009-01-01

    Full Text Available The present study employs time of flight mass spectrometry for quantitative analysis of the local anesthetic drugs ropivacaine and bupivacaine in authentic, pharmaceutical and spiked human plasma as well as in the presence of their impurities 2,6-dimethylaniline and alkaline degradation product. The method is based on time of flight electron spray ionization mass spectrometry technique without preliminary chromatographic separation and makes use of bupivacaine as internal standard for ropivacaine, which is used as internal standard for bupivacaine. A linear relationship between drug concentrations and the peak intensity ratio of ions of the analyzed substances is established. The method is linear from 23.8 to 2380.0 ng mL-1 for both drugs. The correlation coefficient was ≥0.996 in authentic and spiked human plasma. The average percentage recoveries in the ranges of 95.39%–102.75% was obtained. The method is accurate (% RE < 5% and reproducible with intra- and inter-assay precision (RSD% < 8.0%. The quantification limit is 23.8 ng mL-1 for both drugs. The method is not only highly sensitive and selective, but also simple and effective for determination or identification of both drugs in authentic and biological fluids. The method can be applied in purity testing, quality control and stability monitoring for the studied drugs.

  4. Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

    Science.gov (United States)

    Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

    2013-03-05

    A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities.

  5. High-Throughput Analysis of Methylmalonic Acid in Serum, Plasma, and Urine by LC-MS/MS. Method for Analyzing Isomers Without Chromatographic Separation.

    Science.gov (United States)

    Kushnir, Mark M; Nelson, Gordon J; Frank, Elizabeth L; Rockwood, Alan L

    2016-01-01

    Measurement of methylmalonic acid (MMA) plays an important role in the diagnosis of vitamin B12 deficiency. Vitamin B12 is an essential cofactor for the enzymatic carbon rearrangement of methylmalonyl-CoA (MMA-CoA) to succinyl-CoA (SA-CoA), and the lack of vitamin B12 leads to elevated concentrations of MMA. Presence of succinic acid (SA) complicates the analysis because mass spectra of MMA and SA are indistinguishable, when analyzed in negative ion mode and the peaks are difficult to resolve chromatographically. We developed a method for the selective analysis of MMA that exploits the significant difference in fragmentation patterns of di-butyl derivatives of the isomers MMA and SA in a tandem mass spectrometer when analyzed in positive ion mode. Tandem mass spectra of di-butyl derivatives of MMA and SA are very distinct; this allows selective analysis of MMA in the presence of SA. The instrumental analysis is performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in positive ion mode, which is, in combination with selective extraction of acidic compounds, is highly selective for organic acids with multiple carboxyl groups (dicarboxylic, tricarboxylic, etc.). In this method organic acids with a single carboxyl group are virtually undetectable in the mass spectrometer; the only organic acid, other than MMA, that is detected by this method is its isomer, SA. Quantitative measurement of MMA in this method is performed using a deconvolution algorithm, which mathematically resolves the signal corresponding to MMA and does not require chromatographic resolution of the MMA and SA peaks. Because of its high selectivity, the method utilizes isocratic chromatographic separation; reconditioning and re-equilibration of the chromatographic column between injections is unnecessary. The above features of the method allow high-throughput analysis of MMA with analysis cycle time of 1 min.

  6. Analysis of multi-layer ERBS spectra

    Energy Technology Data Exchange (ETDEWEB)

    Marmitt, G.G. [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia); Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS (Brazil); Rosa, L.F.S. [Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS (Brazil); Nandi, S.K. [Electronic Materials Engineering Department, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia); Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh); Vos, M., E-mail: maarten.vos@anu.edu.au [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, The Australian National University, Canberra 0200 (Australia)

    2015-07-15

    Highlights: • Electron Rutherford backscattering (ERBS) spectra are presented. • The spectra are fitted based on physical meaningful quantities. • Very consistent results are obtained for spectra taken under different conditions. • This establishes that ERBS can be used to measure film thicknesses. - Abstract: A systematic way of analysis of multi-layer electron Rutherford backscattering spectra is described. The approach uses fitting in terms of physical meaningful parameters. Simultaneous analysis then becomes possible for spectra taken at different incoming energies and measurement geometries. Examples are given to demonstrate the level of detail that can be resolved by this technique.

  7. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis.

    Science.gov (United States)

    Larsen, K K; Wielandt, D; Schiller, M; Bizzarro, M

    2016-04-22

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185 ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2 ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5 ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120 °C) for several hours, resulting in >97.5% Cr recovery using a

  8. Gas Chromatographic Analysis of Medium Chain Fatty Acids in Coconut Oil

    Directory of Open Access Journals (Sweden)

    Julius Pontoh

    2016-09-01

    Full Text Available Analysis of medium chain of fatty acids in coconut oil becomes important due to their roles in health issues. The present analysis methods for fatty acids present in food mainly focused to the overall fatty acid concentration. The analytical method for specific medium chain fatty acids is not so much be given attention. This research is focused to the analytical methods for these particular fatty acids in coconut oil. Several analytical methods were compared including acid catalyzed, basic catalyzed and acid boron trifluoride catalyzed derivatization. The response of each fatty acid toward the derivatization methods are different. Formation of the fatty acid methyl ester from caprylic and capric was low for acid catalyzed method compared to basic catalyzed method and acid boron trifluoride catalyzed methods. This finding shows that the kinetics of the esterification among the fatty acids are not the same. The analysis of all fatty acids in coconut oil is better using basic catalyzed than the other methods.

  9. Experimental Analysis and Reconstruction of the Morphology of Particulate and Monolithic Chromatographic Beds

    OpenAIRE

    Bruns, Stefan

    2013-01-01

    This dissertation is concerned with the acquisition of three-dimensional image data of chromatography columns in capillary format using confocal laser scanning microscopy as well as with the reconstruction and analysis of the acquired image data in view of the dispersive properties of the separation column. Key aspect in the characterization are radial heterogeneities because in UHPLC these heterogeneities contribute in large part...

  10. Concurrent and supercritical fluid chromatographic analysis of Terpene Lactones and ginkolic acids in Ginko biloba

    Science.gov (United States)

    Supercritical fluid chromatography was used to resolve and determine ginkgolic acids (GAs) and terpene lactones concurrently in ginkgo plant materials and commercial dietary supplements. Analysis of GAs (C13:0, C15:0, C15:1 and C17:1) was carried out by ESI (-) mass detection. The ESI (-) spectra of...

  11. Analysis of Trace Hydrogen Isotopes in Fusion Fuel Cycle by High Precision Gas Chromatograph

    Institute of Scientific and Technical Information of China (English)

    YANG; Li-ling; YANG; Hong-guang; ZHAO; Wei-wei; HE; Chang-shui; LIU; Zhen-xing; ZHAN; Qin

    2013-01-01

    It is essential to analysis of hydrogen isotopes in the fuel cycle system of fusion reactors,gas chromatography(GC)was found to be an effectively analytical technique.Compared with conventional GC,the high-precision GC with a cryogenic column could achieve fairly good performance to reduce the retention time.

  12. Gas chromatographic-mass spectrometric analysis of tar compounds formed during pyrolysis of rice husks

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Stevens, T.W.; Hovestad, A.; Skolnik, V.; Visser, R.

    1991-01-01

    Pyrolysis of agricultural waste to produce fuel gas involves formation of tars as noxious by-products. In this paper the qualitative analysis of tars formed during pyrolysis of rice husks is presented, based on identification by gas chromatography—mass spectrometry and interpolation of retention tim

  13. Hyphenated chromatographic analysis of bioactive gallic acid and quercetin in Hygrophila auriculata (K. Schum) Heine growing wildly in marshy places in India by validated HPTLC method

    Institute of Scientific and Technical Information of China (English)

    Md Sarfaraj Hussain; Sheeba Fareed; Mohammad Ali

    2012-01-01

    Objective: A simple, accurate, and rapid high-performance thin-layer chromatographic (HPTLC) method for simultaneous quantification of the two biologically active flavonoidal compounds, gallic acid and quercetin, in Hygrophila auriculata (K. Schum) Heine (HA) has been established and validated. Methods: Chromatography was performed on aluminium foil-backed silica gel 60 F254 HPTLC plates with the binary mobile phase toluene: ethyl acetate: formic acid (5:4:1, v/v/v). Ultraviolet detection was performed densitometrically at the maximum absorbance wavelength, 270nm. The method was validated for precision, recovery, robustness, specificity, and detection and quantification limits, in accordance with ICH guidelines. Results: The system was found to give compact spots for gallic acid (GA) and quercetin (QE) (Rf value of 0.31 and 0.50, respectively). The limit of detection (23 and 41 ng band-1) limit of quantification (69 and 123 ng band-1), recovery (99.4-99.9 and 98.7-99.4%), and precision (i.e ≤1.98 and 1.97) were satisfactory for gallic acid and quercetin respectively. Linearity range for GA and QE were 100-1000 (r 2= 0.9991) and 150-900 ng band-1 (r2= 0.9956) and the contents estimated as 0.28±0.01% and 0.41±0.01% w/w respectively.Conclusions:This simple, precise and accurate method gave good resolution from other constituents present in the extract. The method has been successfully applied in the analysis and routine quality control of herbal material and formulations containing Hygrophila auriculata (K. Schum) Heine.

  14. Prediction of gas chromatographic retention indices as classifier in non-target analysis of environmental samples.

    Science.gov (United States)

    Ulrich, Nadin; Schüürmann, Gerrit; Brack, Werner

    2013-04-12

    Kováts and Lee retention indices were predicted by the help of experimental and calculated boiling points and also by linear solvation energy relationship (LSER) models. The developed approaches should be applied as classifiers in non-target analysis of environmental samples to identify contaminants. To demonstrate the application as a classifier, an example of 14 isomers with empirical formula C12H10O2 was selected. Furthermore, seven compounds with different molecular composition were used to illustrate the application in non-target analysis, where progressive candidate exclusion is performed. The models help to reduce the number of potential candidates, and seem to be a useful addition to already existing classifiers.

  15. Chromatographic Fingerprint Analysis of Marrubiin in Marrubium vulgare L. via HPTLC Technique

    OpenAIRE

    Keyvan Yousefi; Sanaz Hamedeyazdan; Mohammadali Torbati; Fatemeh Fathiazad

    2016-01-01

    Purpose: In the present study we aimed to quantify marrubiin, as the major active compound, in the aerial parts of Marrubium vulgare from Iran using a HPTLC-densitometry technique. Methods: Quantitative determination of marrubiin in M. vulgare methanol extract was performed by HPTLC analysis via a fully automated TLC scanner. Later on, the in vitro antioxidant activity of the M. vulgare methanol extract was determined using 1,1-diphenyl-2-picryl-hydrazil (DPPH) free radic...

  16. Rigorous evaluation of chemical measurement uncertainty: liquid chromatographic analysis methods using detector response factor calibration

    Science.gov (United States)

    Toman, Blaza; Nelson, Michael A.; Bedner, Mary

    2017-06-01

    Chemical measurement methods are designed to promote accurate knowledge of a measurand or system. As such, these methods often allow elicitation of latent sources of variability and correlation in experimental data. They typically implement measurement equations that support quantification of effects associated with calibration standards and other known or observed parametric variables. Additionally, multiple samples and calibrants are usually analyzed to assess accuracy of the measurement procedure and repeatability by the analyst. Thus, a realistic assessment of uncertainty for most chemical measurement methods is not purely bottom-up (based on the measurement equation) or top-down (based on the experimental design), but inherently contains elements of both. Confidence in results must be rigorously evaluated for the sources of variability in all of the bottom-up and top-down elements. This type of analysis presents unique challenges due to various statistical correlations among the outputs of measurement equations. One approach is to use a Bayesian hierarchical (BH) model which is intrinsically rigorous, thus making it a straightforward method for use with complex experimental designs, particularly when correlations among data are numerous and difficult to elucidate or explicitly quantify. In simpler cases, careful analysis using GUM Supplement 1 (MC) methods augmented with random effects meta analysis yields similar results to a full BH model analysis. In this article we describe both approaches to rigorous uncertainty evaluation using as examples measurements of 25-hydroxyvitamin D3 in solution reference materials via liquid chromatography with UV absorbance detection (LC-UV) and liquid chromatography mass spectrometric detection using isotope dilution (LC-IDMS).

  17. Analysis of proteins and peptides on a chromatographic timescale by electron-transfer dissociation MS

    OpenAIRE

    Udeshi, Namrata D.; Shabanowitz, Jeffrey; Hunt, Donald F.; Rose, Kristie L

    2007-01-01

    Peptide and protein sequence analysis using a combination of gas-phase ion–ion chemistry and tandem MS is described. Samples are converted to multiply charged ions by ESI and then allowed to react with fluoranthene radical anions in a quadrupole linear ion trap mass spectrometer. Electron transfer from the radical anion to the multiply charged peptide or protein promotes random fragmentation along the amide backbone that is independent of peptide or protein size, sequence, or the presence of ...

  18. Nanoelectromechanical Resonator Arrays for Ultrafast, Gas-Phase Chromatographic Chemical Analysis

    OpenAIRE

    Li, Mo; Myers, E. B.; Tang, H. X.; Aldridge, S. J.; McCaig, H. C.; Whiting, J. J.; Simonson, R. J.; Lewis, N. S.; Roukes, M. L.

    2010-01-01

    Miniaturized gas chromatography (GC) systems can provide fast, quantitative analysis of chemical vapors in an ultrasmall package. We describe a chemical sensor technology based on resonant nanoelectromechanical systems (NEMS) mass detectors that provides the speed, sensitivity, specificity, and size required by the microscale GC paradigm. Such NEMS sensors have demonstrated detection of subparts per billion (ppb) concentrations of a phosphonate analyte. By combining two channels of NEMS detec...

  19. Rigorous evaluation of chemical measurement uncertainty: Liquid chromatographic analysis methods using detector response factor calibration.

    Science.gov (United States)

    Toman, Blaza; Nelson, Michael A; Bedner, Mary

    2017-06-01

    Chemical measurement methods are designed to promote accurate knowledge of a measurand or system. As such, these methods often allow elicitation of latent sources of variability and correlation in experimental data. They typically implement measurement equations that support quantification of effects associated with calibration standards and other known or observed parametric variables. Additionally, multiple samples and calibrants are usually analyzed to assess accuracy of the measurement procedure and repeatability by the analyst. Thus, a realistic assessment of uncertainty for most chemical measurement methods is not purely bottom-up (based on the measurement equation) or top-down (based on the experimental design), but inherently contains elements of both. Confidence in results must be rigorously evaluated for the sources of variability in all of the bottom-up and top-down elements. This type of analysis presents unique challenges due to various statistical correlations among the outputs of measurement equations. One approach is to use a Bayesian hierarchical (BH) model which is intrinsically rigorous, thus making it a straightforward method for use with complex experimental designs, particularly when correlations among data are numerous and difficult to elucidate or explicitly quantify. In simpler cases, careful analysis using GUM Supplement 1 (MC) methods augmented with random effects meta analysis yields similar results to a full BH model analysis. In this article we describe both approaches to rigorous uncertainty evaluation using as examples measurements of 25-hydroxyvitamin D3 in solution reference materials via liquid chromatography with UV absorbance detection (LC-UV) and liquid chromatography mass spectrometric detection using isotope dilution (LC-IDMS).

  20. Global stability analysis of axisymmetric boundary layers

    CERN Document Server

    Vinod, N

    2016-01-01

    This paper presents the linear global stability analysis of the incompressible axisymmetric boundary layer on a circular cylinder. The base flow is parallel to the axis of the cylinder at inlet. The pressure gradient is zero in the streamwise direction. The base flow velocity profile is fully non-parallel and non-similar in nature. The boundary layer grows continuously in the spatial directions. Linearized Navier-Stokes(LNS) equations are derived for the disturbance flow quantities in the cylindrical polar coordinates. The LNS equations along with homogeneous boundary conditions forms a generalized eigenvalues problem. Since the base flow is axisymmetric, the disturbances are periodic in azimuthal direction. Chebyshev spectral collocation method and Arnoldi's iterative algorithm is used for the solution of the general eigenvalues problem. The global temporal modes are computed for the range of Reynolds numbers and different azimuthal wave numbers. The largest imaginary part of the computed eigenmodes are nega...

  1. ANALYSIS OF DIFFERENT BRANDS OF PARACETAMOL 500mg TABLETS USED IN MAIDUGURI, USING ULTRA VIOLET SPECTROPHOTOMETRIC AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC (HPLC) METHODS

    OpenAIRE

    Sani Ali Audu; Alemika Emmanuel Taiwo; Bala Fatima Mohammed; Sani Musa; Ramat. Bukola

    2012-01-01

    The study involves quantitative analysis of eight (8) different brands (samples) of Paracetamol 500mg tablets used in Maiduguri, using Ultra Violet Spectrophotometric and High Performance Liquid Chromatographic methods, in which the samples were dissolved in 0.1M NaOH and distilled water and their various absorbances determined at wavelength of 257nm and the HPLC method. The results obtained were compared with that of the standard. Percentage content and content in mg for each sample was calc...

  2. 膜分离技术在色谱分析中的应用%The Application of Membrane Separation Technology in Chromatographic Analysis

    Institute of Scientific and Technical Information of China (English)

    梁君妮; 赵钰玲; 李春喜; 杨丽君

    2016-01-01

    The development and application of membrane separation technology in chromatographic analysis were summarized in the review, the development trend and prospects of membrane separation technology in the future was prospected.%阐述了膜分离技术在色谱分析中的应用及发展,展望了膜分离技术在色谱分析方面的发展趋势和应用前景。

  3. Pattern recognition analysis of chromatographic fingerprints of Crocus sativus L. secondary metabolites towards source identification and quality control.

    Science.gov (United States)

    Aliakbarzadeh, Ghazaleh; Sereshti, Hassan; Parastar, Hadi

    2016-05-01

    Chromatographic fingerprinting is an effective methodology for authentication and quality control of herbal products. In the presented study, a chemometric strategy based on multivariate curve resolution-alternating least squares (MCR-ALS) and multivariate pattern recognition methods was used to establish a gas chromatography-mass spectrometry (GC-MS) fingerprint of saffron. For this purpose, the volatile metabolites of 17 Iranian saffron samples, collected from different geographical regions, were determined using the combined method of ultrasound-assisted solvent extraction (UASE) and dispersive liquid-liquid microextraction (DLLME), coupled with GC-MS. The resolved elution profiles and the related mass spectra obtained by an extended MCR-ALS algorithm were then used to estimate the relative concentrations and to identify the saffron volatile metabolites, respectively. Consequently, 77 compounds with high reversed match factors (RMFs > 850) were successfully determined. The relative concentrations of these compounds were used to generate a new data set which was analyzed by multivariate data analysis methods including principal component analysis (PCA) and k-means. Accordingly, the saffron samples were categorized into five classes using these techniques. The results revealed that 11 compounds, as biomarkers of saffron, contributed to the class discrimination and characterization. Eleven biomarkers including nine secondary metabolites of saffron (safranal, α- and β-isophorone, phenylethyl alcohol, ketoisophorone, 2,2,6-trimethyl-1,4-cyclohexanedione, 2,6,6-trimethyl-4-oxo-2-cyclohexen-1-carbaldehyde, 2,4,4-trimethyl-3-carboxaldehyde-5-hydroxy-2,5-cyclohexadien-1-one, and 2,6,6-trimethyl-4-hydroxy-1-cyclohexene-1-carboxaldehyde (HTCC)), a primary metabolite (linoleic acid), and a long chain fatty alcohol (nanocosanol) were distinguished as the saffron fingerprint. Finally, the individual contribution of each biomarker to the classes was determined by the

  4. Evaluation of two adsorbents for diffusive sampling and thermal desorption-gas chromatographic analysis of monoterpenes in air.

    Science.gov (United States)

    Sunesson, A L; Sundgren, M; Levin, J O; Eriksson, K; Carlson, R

    1999-02-01

    Tube type samplers with two different adsorbents, Chromosorb 106 and Tenax TA, were evaluated by laboratory experiments and field tests for simultaneous diffusive sampling of alpha-pinene, beta-pinene and delta 3-carene and subsequent thermal desorption-gas chromatographic analysis. No statistically significant effects of exposure time, concentrations of monoterpenes or relative humidity were found for samplers with Chromosorb 106 when running a factorial design, with the exception of the adsorption of delta 3-carene, for which some weak effects were noted. Samplers with Tenax TA were affected by the sampling time as well as the concentration for all terpenes, with a strong interaction effect between these two factors. The terpenes showed good storage stability on both adsorbents. No effect of back-diffusion was noted when using Chromosorb 106, while Tenax TA showed some back-diffusion effects. The uptake rates, in ml min-1, for the terpenes on Chromosorb 106 were 0.36 for alpha-pinene, 0.36 for beta-pinene and 0.40 for delta 3-carene. The corresponding average values on Tenax TA were 0.30 for alpha-pinene, 0.32 for beta-pinene and 0.38 for delta 3-carene. The field validation proved that diffusive sampling on Chromosorb 106 agreed well with pumped sampling on charcoal for stationary samples, while the personal samples indicated a discrepancy of 25% between Chromosorb 106 and charcoal samples. Tenax TA generally gave lower results than Chromosorb 106 in all field samples. Samplers packed with Chromosorb 106 could be used to monitor terpene levels in workplaces such as sawmills. The major advantages with this method are the sampling procedure, which is simple to perform compared to other techniques, the easily automated analysis procedure and the possibility to reuse the samplers.

  5. Recent advances in metal-organic frameworks and covalent organic frameworks for sample preparation and chromatographic analysis.

    Science.gov (United States)

    Wang, Xuan; Ye, Nengsheng

    2017-09-04

    In the field of analytical chemistry, sample preparation and chromatographic separation are two core procedures. The means by which to improve the sensitivity, selectivity and detection limit of a method have become a topic of great interest. Recently, porous organic frameworks, such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely used in this research area because of their special features, and different methods have been developed. This review summarizes the applications of MOFs and COFs in sample preparation and chromatographic stationary phases. The MOF- or COF-based solid-phase extraction (SPE), solid-phase microextraction (SPME), gas chromatography (GC), high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) methods are described. The excellent properties of MOFs and COFs have resulted in intense interest in exploring their performance and mechanisms for sample preparation and chromatographic separation. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. The application of HP-GFC chromatographic method for the analysis of oligosaccharides in bioactive complexes

    Directory of Open Access Journals (Sweden)

    Savić Ivan

    2009-01-01

    Full Text Available The aim of this work was to optimize a GFC method for the analysis of bioactive metal (Cu, Co and Fe complexes with olygosaccharides (dextran and pullulan. Bioactive metal complexes with olygosaccharides were synthesized by original procedure. GFC was used to study the molecular weight distribution, polymerization degree of oligosaccharides and bioactive metal complexes. The metal bounding in complexes depends on the ligand polymerization degree and the presence of OH groups in coordinative sphere of the central metal ion. The interaction between oligosaccharide and metal ions are very important in veterinary medicine, agriculture, pharmacy and medicine.

  7. Simultaneous chromatographic analysis of photoinitiators and amine synergists in food contact materials.

    Science.gov (United States)

    Lago, M A; Rodríguez-Bernaldo de Quirós, A; Sendón, R; Bustos, J; Santillana, M I; Paseiro, P

    2014-07-01

    Photoinitiators (PIs) are components of UV-cured inks widely used in printing of food packaging. These substances can migrate into food and may be a hazard to human health. High-performance liquid chromatography with diode-array detection (HPLC-DAD) has been used for analysis of PIs and amine synergists in food packaging. Analysis was performed with a Kromasil C18 column (250 mm × 3.2 mm i.d., 5 μm particle size) with a binary mobile phase gradient prepared from acetonitrile and Milli-Q water. The flow rate was 0.5 mL min(-1). The method enables separation of fourteen PIs and amine synergists in a single run. The method was validated for linearity, repeatability, and limits of detection and quantification. Excellent sensitivity (LODs ≤ 1.56 μg dm(2)) and appropriate repeatability (RSD (n = 10) <0.9%) were achieved. Different types of food packaging material including plastic films, cardboard, and cans were analyzed and PIs were detected in 47% of the samples tested (n = 17). Positive samples were confirmed by use of LC-MS-MS in positive electrospray ionization (ESI) mode.

  8. Comparative studies of peak intensities and chromatographic separation of proteolytic digests, PTMs, and intact proteins obtained by nanoLC-ESI MS analysis at room and elevated temperatures.

    Science.gov (United States)

    Moskovets, Eugene V; Ivanov, Alexander R

    2016-06-01

    This work demonstrates that the chromatographic separation performed at highly stabilized elevated temperature results in significant improvements in sensitivity, quantitative accuracy, chromatographic resolution, and run-to-run reproducibility of nanoLC-MS analysis of complex peptides mixtures. A newly developed platform was shown to provide conditions for accurate temperature stabilization and temperature homogeneity when performing nanoLC-ESI MS analysis. We quantitatively assessed and compared the recovery of peptides and small proteins from nanoLC columns at room and elevated temperatures. We found that analyses performed at highly stabilized elevated temperatures led to improved detection sensitivity, reproducibility, and chromatographic resolution in reversed-phase LC separation of unmodified peptides (both hydrophilic and hydrophobic), post-translationally modified peptides (O-phosphorylated), and small intact proteins. The analytical benefits of elevated temperatures for qualitative and quantitative proteomic LC-MS profiling were demonstrated using mixtures of synthetic peptides, tryptic digests of mixtures of model proteins, and digested total lysates of isolated rat kidney mitochondria. The effect of elevated temperature on the ion suppression was also demonstrated. Graphical Abstract A fragment of overlaid LC retention time-m/z planar views demonstrates the improved separation performance in the analysis of a complex peptide mixture at elevated temperature. Retention time-m/z 2D peptide features detected at 60 °C (magenta) were matched and aligned with features detected at room temperature (green).

  9. High-performance liquid chromatographic analysis of phlorotannins from the brown alga Fucus vesiculosus.

    Science.gov (United States)

    Koivikko, Riitta; Loponen, Jyrki; Pihlaja, Kalevi; Jormalainen, Veijo

    2007-01-01

    Separating individual compounds by HPLC represents an effective method for the detection and quantification of phenolic compounds and has been widely utilised. However, phlorotannins are commonly quantified using colorimetric methods, as the total amount of the whole compound group. In the present paper the separation of a set of individual soluble phlorotannins from the phenolic crude extract of Fucus vesiculosus was achieved by HPLC with UV photodiode array detection. Different gradient programs for reversed- and normal-phase HPLC methods were developed and tested. Normal-phase (NP) conditions with a silica stationary phase and a mobile phase with a linear gradient of increasing polarity were found to separate 16 individual components of the phenolic extract. The suitability of the NP-HPLC method for mass spectrometric application was preliminarily tested. Sample preparation was found to be a critical step in the analysis owing to the rapid oxidation of phlorotannins; ascorbic acid was used as an antioxidant.

  10. Development of a carbohydrate silylation method in ionic liquids for their gas chromatographic analysis.

    Science.gov (United States)

    Ruiz-Aceituno, L; Carrero-Carralero, C; Ramos, L; Martinez-Castro, I; Sanz, M L

    2013-07-17

    This paper reports on the feasibility of silylation of low molecular weight carbohydrates dissolved in different ionic liquids (ILs) for their further analysis by gas chromatography (GC). Derivatization reagents (nature and amounts), temperature and time of reaction and stirring conditions were evaluated for different carbohydrates (i.e., glucose, mannose, fructose and lactose) dissolved in 1-ethyl-3-methylimidazolium dicyanamide [EMIM][DCA]. Evaluation of conformational isomerism of glucose dissolved in [EMIM][DCA] revealed the effect of the time of dissolution in the equilibration of α- and β-furanoses (up to 3% and 6%, respectively, after 70 h of incubation) and that 21 h sufficed to obtain results similar to those provided by the reference method involving pyridine. Once optimized, the proposed derivatization procedure provided satisfactory yields (i.e., close to 100%) using 100 μL of trimethylsilylimidazole (TMSI) at mild conditions (25°C) for a relatively short time (1h) for most of the investigated carbohydrates. Under these experimental conditions, linear responses (i.e., R(2) better than 0.974) were obtained in the tested range of 0.25-1mg of the derivatized target compounds. Other reagents, such as N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)+1% trimethylchlorosilane (TMCS), were successfully used under ultrasonic conditions for aldose monosaccharides and disaccharides derivatization, while BSTFA was useful for ketose monosaccharides. The possibility of using the proposed method for the derivatization of selected carbohydrates dissolved in different ILs and the efficiency of the method applied to the analysis of carbohydrates present in real samples (fruit juices) have also been investigated.

  11. Chromatographic and spectroscopic analysis of heavy crude oil mixtures with emphasis in nuclear magnetic resonance spectroscopy: A review

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sandra L. [Department of Chemistry, QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal); Silva, Artur M.S., E-mail: artur.silva@ua.pt [Department of Chemistry, QOPNA, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal); Ribeiro, Jorge C. [Petrogal SA, Laboratory of Matosinhos Refinery, Rua Belchior Robles, 4452-852 Leca da Palmeira, Matosinhos (Portugal); Martins, Fernando G. [LEPAE, University of Porto, Engineering Faculty, Department of Chemical Engineering, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Da Silva, Francisco A.; Silva, Carlos M. [Department of Chemistry, CICECO, University of Aveiro, Campus de Santiago, 3810-193 Aveiro (Portugal)

    2011-11-30

    Graphical abstract: The chromatographic and spectroscopic techniques used to characterize heavy crude oils, although more focused in the nuclear magnetic resonance spectroscopy as the technique of choice, due to its capability to provide great information on the chemical nature of individual types of proton and carbon atoms in different and complex mixtures of crude oils are described. This review is based on 65 references and describes in a critical and interpretative ways the advantages of the NMR spectroscopy as a main technique to be used in crude oil refining industries that want to characterize crude oil fractions and the obtained refined products. Highlights: Black-Right-Pointing-Pointer Chromatogrfaphic and spectroscopic techniques used to characterize heavy crude oils have been reviewed. Black-Right-Pointing-Pointer This review describes in a critical and interpretative ways the advantages of the NMR spectroscopy as a main technique to be used in crude oil refining industries. Black-Right-Pointing-Pointer The progress in the interpretation of the NMR spectra and of different multivariate data analyses and their potential in the identification and characterization of hydrocarbons and their physical and chemical properties have also been reviewed. - Abstract: The state of the art in the characterization of heavy crude oil mixtures is presented. This characterization can be done by different techniques, such as gas chromatography (GC), high performance liquid chromatography (HPLC), thin layer chromatography (TLC), infrared spectroscopy (IR), Raman spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). Nuclear magnetic resonance spectroscopy is the technique of choice due to its capability to provide information on the chemical nature of individual types of hydrogen and carbon atoms in different and complex mixtures of crude oils. The progress made in the interpretation of the NMR spectra with the development of new NMR

  12. Gas chromatographic analysis of histamine in mahi-mahi (Coryphaena hippurus).

    Science.gov (United States)

    Antoine, Francis R; Wei, Cheng-I; Otwell, W Steve; Sims, Charlie A; Littell, Ramon C; Hogle, Amanda D; Marshall, Maurice R

    2002-08-14

    Several authors have studied histamine using gas chromatography (GC) as a tool for quantitation, but the methods used were not always suitable depending on the kind of food. Problems frequently cited include incomplete histamine elution from the columns and peak tailing. Histamine is of interest because it is the factor common to all cases of scombroid poisoning, it has physiological and biological activity, and it is a chemical indicator of fish quality. In this study a modified GC method was used to quantify histamine in mahi-mahi (Coryphaena hippurus). Mean recovery was 67% for the GC method, compared with 90% for the AOAC fluorometric method. There was a 0.96 correlation of the GC histamine values with those of the AOAC fluorometric method. A temperature program, splitless/split injection, and analyte cleanup were essential for GC properties. Histamine retention time was 8.2 min. The method allowed peak height to be used for quantitation and simultaneous analysis of cadaverine and putrescine.

  13. Determination of Milk Fat Adulteration with Vegetable Oils and Animal Fats by Gas Chromatographic Analysis.

    Science.gov (United States)

    Kim, Jin-Man; Kim, Ha-Jung; Park, Jung-Min

    2015-09-01

    This study assessed the potential application of gas chromatography (GC) in detecting milk fat (MF) adulteration with vegetable oils and animal fats and of characterizing samples by fat source. One hundred percent pure MF was adulterated with different vegetable oils and animal fats at various concentrations (0%, 10%, 30%, 50%, 70%, and 90%). GC was used to obtain the fatty acid (FA) profiles, triacylglycerol (TG) contents, and cholesterol contents. The pure MF and the adulterated MF samples were discriminated based on the total concentrations of saturated FAs and on the 2 major FAs (oleic acid [C18:1n9c] and linoleic acid [C18:2n6c], TGs [C52 and C54], and cholesterol contents using statistical analysis to compared difference. These bio-markers enabled the detection of as low as 10% adulteration of non-MF into 100% pure MF. The study demonstrated the high potential of GC to rapidly detect MF adulteration with vegetable and animal fats, and discriminate among commercial butter and milk products according to the fat source. These data can be potentially useful in detecting foreign fats in these butter products. Furthermore, it is important to consider that several individual samples should be analyzed before coming to a conclusion about MF authenticity.

  14. Comparative phytochemical investigation of the sources of ayurvedic drug Patha: A chromatographic fingerprinting analysis

    Directory of Open Access Journals (Sweden)

    Hullatti K

    2010-01-01

    Full Text Available Standardization of herbal drugs based on their chemical and biological activity profile is an important prerequisite for acquiring the herbal market. The main problem encountered in standardization of Ayurvedic drugs is proper identification of the source plant. The present study was aimed to establish identification characters, quality control parameters, chemical and biological parameters for roots of three plants Cissampelos pareira, Cyclea peltata and Stephania japonica (Fam. Menispermaceae which are being used as source of Patha, in the market. All the three plant were subjected for evaluation of quality control parameters as per WHO guidelines and root extracts and total alkaloidal fractions were subjected for HPTLC and HPLC fingerprinting analysis using a marker compound Bebeerine isolated from roots of Cissampelos pareira. The parameters studied clearly indicated the significant differences among the three plant materials. The roots of Cissampelos pareira can be distinguished from other two plants by presence of high concentration of alkaloids especially the presence of high concentration of pharmacologically active alkaloid bebeerine, which was found to be present in very low concentration in Stephania japonica and absent in roots of Cyclea peltata. The roots of Cyclea peltata were found to contain high concentration of saponins and comparatively in low concentration in Cissampelos pareira where as it was found to be absent in roots of Stephania japonica.

  15. Chromatographic analysis of Polygalae Radix by online hyphenating pressurized liquid extraction

    Science.gov (United States)

    Song, Yuelin; Song, Qingqing; Li, Jun; Shi, Shepo; Guo, Liping; Zhao, Yunfang; Jiang, Yong; Tu, Pengfei

    2016-06-01

    Practicing “green analytical chemistry” is of great importance when profiling the chemical composition of complex matrices. Herein, a novel hybrid analytical platform was developed for direct chemical analysis of complex matrices by online hyphenating pressurized warm water extraction followed by turbulent flow chromatography coupled with high performance liquid chromatography-tandem mass spectrometry (PWWE-TFC-LC-MS/MS). Two parallel hollow guard columns acted as extraction vessels connected to a long narrow polyether ether ketone tube, while warm water served as extraction solvent and was delivered at a flow rate of 2.5 mL/min to generate considerable back pressure at either vessel. A column oven heated both the solvent and crude materials. A TFC column, which is advantageous for the comprehensive trapping of small molecular substances from fluids under turbulent flow conditions, was employed to transfer analytes from the PWWE module to LC-MS/MS. Two electronic valves alternated each vessel between extraction and elution phases. As a proof-of-concept, a famous herbal medicine for the treatment of neurodegenerative disorders, namely Polygalae Radix, was selected for the qualitative and quantitative analyses. The results suggest that the hybrid platform is advantageous in terms of decreasing time, material, and solvent consumption and in its automation, versatility, and environmental friendliness.

  16. High-performance liquid chromatographic analysis of as-synthesised N,N'-dimethylformamide-stabilised gold nanoclusters product

    Science.gov (United States)

    Xie, Shunping; Paau, Man Chin; Zhang, Yan; Shuang, Shaomin; Chan, Wan; Choi, Martin M. F.

    2012-08-01

    Reverse-phase high-performance liquid chromatographic (RP-HPLC) separation and analysis of polydisperse water-soluble gold nanoclusters (AuNCs) stabilised with N,N'-dimethylformamide (DMF) were investigated. Under optimal elution gradient conditions, the separation of DMF-AuNCs was monitored by absorption and fluorescence spectroscopy. The UV-vis spectral characteristics of the separated DMF-AuNCs have been captured and they do not possess distinct surface plasmon resonance bands, indicating that all DMF-AuNCs are small AuNCs. The photoluminescence emission spectra of the separated DMF-AuNCs are in the blue-light region. Moreover, cationic DMF-AuNCs are for the first time identified by ion chromatography. Our proposed RP-HPLC methodology has been successfully applied to separate AuNCs of various Au atoms as well as DMF-stabilised ligands. Finally, the composition of the separated DMF-AuNCs was confirmed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry and electrospray ionisation mass spectrometry, proving that the as-synthesised DMF-AuNCs product consists of Au10+, Au10, Au11, Au12, Au13, and Au14 NCs stabilised with various numbers of DMF ligands.Reverse-phase high-performance liquid chromatographic (RP-HPLC) separation and analysis of polydisperse water-soluble gold nanoclusters (AuNCs) stabilised with N,N'-dimethylformamide (DMF) were investigated. Under optimal elution gradient conditions, the separation of DMF-AuNCs was monitored by absorption and fluorescence spectroscopy. The UV-vis spectral characteristics of the separated DMF-AuNCs have been captured and they do not possess distinct surface plasmon resonance bands, indicating that all DMF-AuNCs are small AuNCs. The photoluminescence emission spectra of the separated DMF-AuNCs are in the blue-light region. Moreover, cationic DMF-AuNCs are for the first time identified by ion chromatography. Our proposed RP-HPLC methodology has been successfully applied to separate AuNCs of

  17. Chromatographic preparation and kinetic analysis of interactions between tabun enantiomers and acetylcholinesterase.

    Science.gov (United States)

    Tenberken, O; Thiermann, H; Worek, F; Reiter, G

    2010-06-02

    The easy accessibility to highly toxic OP (organophosphorus)-type chemical warfare agents (nerve agents) underlines the necessity for an effective medical treatment. Acute OP toxicity is primarily caused by inhibition of acetylcholinesterase (AChE, EC 3.1.1.7). Reactivators (oximes) of inhibited AChE are a mainstay of treatment. However, the commercially available compounds, obidoxime and pralidoxime, are considered rather ineffective against various nerve agents, including tabun. OP-type chemical warfare agents include an asymmetrical P-atom and consist of at least two stereoisomers. Previous studies with the nerve agents sarin and soman showed marked differences between (-)- and (+)-P isomers regarding AChE inhibition and stability in biological matrices. Hence, stereoselectivity is a key parameter for the development of optimized treatment. In the present study, the tabun enantiomers were isolated by semi-preparative liquid-chromatography (LC) with offline analysis by GC-PCI-MS and final characterization of optical purity (99.98% (-)-tabun and 99.83% (+)-tabun) and specific optical rotation. The inhibition and reactivation kinetics of the tabun enantiomers were determined with human and swine AChE and the aging kinetics with human AChE. The results show a large difference in the inhibitory potency between (-)- and (+)-tabun. The determination of reactivation and aging kinetics indicates that both reactions are at least in part determined by the residual (-)-tabun contamination (0.17%) of the (+)-tabun preparation. These data provide further insight into the kinetic interactions between tabun enantiomers and AChE and may contribute to the development of more effective treatment options.

  18. Chromatographic analysis of Hb S for the diagnosis of various sickle cell disorders in Pakistan.

    Science.gov (United States)

    Hashmi, Nazish Khalid; Moiz, Bushra; Nusrat, Maliha; Hashmi, Mashhooda Rasool

    2008-08-01

    Sickle cell disease remains a relatively obscure theme in research on haemoglobinopathies in Pakistan. Limited data is available regarding its prevalence in the country. The objective of our study was not only to estimate the frequency of different sickle cell diseases but also to provide quantitative estimation of haemoglobin S and other haemoglobin variants using an automated high-performance liquid chromatography (HPLC) system. For this purpose, we retrospectively evaluated the results of HPLC performed on all patients with suspected haemoglobinopathies during the years 2005 and 2006. Information derived from various sources was used to identify a particular genotype by analysing each sample containing Hb S with respect to haemoglobin, red cell indices and levels of various associated haemoglobin variants. Analysis of 15,699 samples identified 302 patients with Hb S (1.92%). The genotypes identified included Sbeta(0) (46.7%), SS (19.2%), SA (11.6%), Sbeta(+) (8.6%) and SD (2.3%). Thirty-five cases could not be categorised and were labelled 'unclassified'. Majority of the patients (62.3%) were below the age of 18 years. Balochistan, which is the largest province based on the area, yielded the highest number of patients (n = 140). In the Sbeta(0) group, the mean haemoglobin and Hb S were lower in children compared to adults (p value of 0.001 and 0.016, respectively). We conclude that sickle cell disorders are prevalent in Pakistan to a significant extent, being concentrated in certain areas of the country. We present the first report of various haemoglobin S genotypes from our population. It is hoped that it will act as a database to characterise the same for our population.

  19. Chromatographic analysis with different detectors in the chemical characterisation and dereplication of African propolis.

    Science.gov (United States)

    Zhang, Tong; Omar, Ruwida; Siheri, Weam; Al Mutairi, Sultan; Clements, Carol; Fearnley, James; Edrada-Ebel, RuAngelie; Watson, David

    2014-03-01

    Propolis or bee glue has very diverse composition and is potentially a source of biologically active compounds. Comprehensive chemical profiling was performed on 22 African propolis samples collected from the sub-Saharan region of Africa by using various hyphenated analytical techniques including Liquid Chromatography (LC)-UltraViolet Detection (UV)-Evaporative Light Scattering Detection (ELSD), LC-High Resolution Mass Spectrometry (HRMS), Gas Chromatography (GC)-MS and LC-Diode Array Detector (DAD)-HRMS/MS. The diversity of the composition of these African propolis samples could be observed by heat mapping the LC-UV and ELSD data. The characteristic chemical components were uncovered by applying Principal Component Analysis (PCA) to the LC-HRMS data and a preliminary dereplication was carried out by searching their accurate masses in the Dictionary of Natural Products (DNP). A further identification was achieved by comparing their GC-MS or LC-DAD-HRMS/MS spectra with previously published data. Generally no clear geographic delineation was observed in the classification of these African propolis samples. Triterpenoids were found as the major chemical components in more than half of the propolis samples analysed in this study and some others were classified as temperate and Eastern Mediterranean type of propolis. Based on the comparative chemical profiling and dereplication studies one uncommon propolis from southern Nigeria stood out from others by presenting prenylated isoflavonoids, which indicated that it was more like Brazilian red propolis, and more significantly a high abundance of stilbenoid compounds which could be novel in propolis. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Validation of high-performance liquid chromatographic method for analysis of fluconazole in microemulsions and liquid crystals

    Directory of Open Access Journals (Sweden)

    Hilris Rocha e Silva

    2014-04-01

    Full Text Available In recent decades, there has been a significant increase in the incidence of fungal diseases. Certain fungal diseases cause cutaneous lesions and in the usual treatment, generally administred orally, the drug reaches the site of action with difficulty and its concentration is too low. An approach much explored in recent years is the development of nanotechnology-based drug delivery systems, and microemulsions (ME and liquid crystals (LC are promising. ME and LC were developed with oleic acid or copaiba oil as the oil phase, propoxyl (5OP ethoxyl (20 OE cetyl alcohol as surfactant and water. An analytical method to assess the incorporation of fluconazole (FLU in the systems under study was validated according to guidelines of the International Conference on Harmonization (ICH guidelines and the Brazilian Food, Drug and Sanitation Agency (ANVISA. The method was conducted on a C18-RP column (250 × 4.6 mm i.d., maintained at room temperature. The mobile phase consisted of acetonitrile and water (50:50, v/v, run at a flow rate of 1.0mL/min and using ultraviolet detection at 210nm. The chromatographic separation was obtained with a retention time of 6.3min, and was linear in the range of 20-400 µg/mL (r2=0.9999. The specificity showed no interference of the excipients. The accuracy was 100.76%. The limits of detection and quantitation were 0.057 and 0.172 µg.mL-1, respectively. Moreover, method validation demonstrated satisfactory results for precision and robustness. The proposed method was applied for the analysis of the incorporation of FLU in ME and LC, contributing to improve the quality control and to assure the therapeutic efficacy.

  1. Analysis of ketone bodies in exhaled breath and blood of ten healthy Japanese at OGTT using a portable gas chromatograph.

    Science.gov (United States)

    Tanda, Naoko; Hinokio, Yoshinori; Washio, Jumpei; Takahashi, Nobuhiro; Koseki, Takeyoshi

    2014-11-24

    Ketone bodies including acetone are disease biomarkers for diabetes that sometimes causes severe ketoacidosis. The present study was undertaken to clarify the significance of exhaled acetone and plasma ketone bodies at bedside in a clinical setting. The oral glucose tolerance test (OGTT) was performed in 10 healthy Japanese volunteers (five females and five males). Exhaled breath acetone and volatile sulfide compounds (VSCs) in mouth air were measured simultaneously with blood sampling during the OGTT using a portable gas chromatograph equipped with an In2O3 thick-film type gas sensor and a VSC monitor. Acetone, β-hydroxybutyrate (β-OHB) and acetoacetate (AcAc) in blood plasma as well as glucose and insulin were examined. Oral conditions were examined based on the Community Periodontal Index (CPI) by one dentist. In addition, the same type of analysis was applied to two uncontrolled type 2 diabetes mellitus patients hospitalized at Tohoku University Hospital. Exhaled acetone was measured at the same time as blood withdrawal in the morning before breakfast and at night before bed at the beginning, the middle, and the end of hospitalization. All volunteers showed normal OGTT patterns with no ketonuria and periodontitis; however, there were significant correlations between breath acetone and plasma β-ΟΗΒ and between breath acetone and plasma AcAc under fasting conditions. Breath acetone of the type 2 diabetes mellitus patients showed positive correlations with plasma glucose when the level of plasma glucose tended to decrease during hospitalization. In spite of a very limited number of cases, our results support the idea that exhaled breath acetone may be related to plasma β-OHB and AcAc, which reflect glucose metabolism in the body.

  2. An atmospheric pressure chemical ionisation liquid chromatographic-tandem mass spectrometry method for the analysis of benzodiazepines in urine.

    Science.gov (United States)

    Dunlop, S; Hayes, K; Leavy, P; Cusack, D; Maguire, R

    2017-10-01

    The objective of this work was to establish an analytical method for the analysis of 7 Benzodiazepines (diazepam, oxazepam, temazepam, nordiazepam, desalkylflurazepam, alprazolam and α-hydroxyalprazolam) in urine specimens taken from drivers suspected of driving under the influence of drugs. The specimen, calibrator and control preparation involved hydrolysis of conjugated benzodiazepines using β-glucuronidase in sodium acetate buffer, with incubation at 60°C for 2h. Specimens were then centrifuged, before being diluted 1 in 5 (total dilution 1 in 10), with 10% acetonitrile in water. Specimens were analysed using a Shimadzu Prominence UPLC coupled to an AB Sciex 4000 QTrap LC-MS-MS. The chromatographic column was a Shim-pack XR ODS 2.2μm. 3.0×50mm column and the mobile phase was a binary gradient system comprising of mobile phase A which was an ammonium formate/formic acid buffer dissolved in water and mobile phase B which was an ammonium formate/formic acid buffer dissolved in Acetonitrile. APCI was selected as the ionisation technique and the MS was operated in MRM mode, monitoring 2 transitions per analyte. The validation of the method is described. The method was found to be linear, accurate and precise (within day and between day) for diazepam, oxazepam, temazepam, nordiazepam, desalkylflurazepam, alprazolam and α-hydroxyalprazolam. The results of 480 cases are reviewed and show that alprazolam use was found in 35% of cases. Use of benzodiazepines resulting in oxazepam, nordiazepam or temazepam were found ca. 70% of cases analysed. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Characterization of thermal desorption with the Deans-switch technique in gas chromatographic analysis of volatile organic compounds.

    Science.gov (United States)

    Ou-Yang, Chang-Feng; Huang, Ying-Xue; Huang, Ting-Jyun; Chen, Yong-Shen; Wang, Chieh-Heng; Wang, Jia-Lin

    2016-09-02

    This study presents a novel application based on the Deans-switch cutting technique to characterize the thermal-desorption (TD) properties for gas chromatographic (GC) analysis of ambient volatile organic compounds (VOCs). Flash-heating of the sorbent bed at high temperatures to desorb trapped VOCs to GC may easily produce severe asymmetric or tailing GC peaks affecting resolution and sensitivity if care is not taken to optimize the TD conditions. The TD peak without GC separation was first examined for the quality of the TD peak by analyzing a standard gas mixture from C2 to C12 at ppb level. The Deans switch was later applied in two different stages. First, it was used to cut the trailing tail of the TD peak, which, although significantly improved the GC peak symmetry, led to more loss of the higher boiling compounds than the low boiling ones, thus suggesting compound discrimination. Subsequently, the Deans switch was used to dissect the TD peak into six 30s slices in series, and an uneven distribution in composition between the slices were found. A progressive decrease in low boiling compounds and increase in higher boiling ones across the slices indicated severe inhomogeneity in the TD profile. This finding provided a clear evidence to answer the discrimination problem found with the tail cutting approach to improve peak symmetry. Through the use of the innovated slicing method based on the Deans-switch cutting technique, optimization of TD injection for highly resolved, symmetric and non-discriminated GC peaks can now be more quantitatively assessed and guided.

  4. Chemometric processing of second-order liquid chromatographic data with UV-vis and fluorescence detection. A comparison of multivariate curve resolution and parallel factor analysis 2.

    Science.gov (United States)

    Bortolato, Santiago A; Olivieri, Alejandro C

    2014-09-01

    Second-order liquid chromatographic data with multivariate spectral (UV-vis or fluorescence) detection usually show changes in elution time profiles from sample to sample, causing a loss of trilinearity in the data. In order to analyze them with an appropriate model, the latter should permit a given component to have different time profiles in different samples. Two popular models in this regard are multivariate curve resolution-alternating least-squares (MCR-ALS) and parallel factor analysis 2 (PARAFAC2). The conditions to be fulfilled for successful application of the latter model are discussed on the basis of simple chromatographic concepts. An exhaustive analysis of the multivariate calibration models is carried out, employing both simulated and experimental chromatographic data sets. The latter involve the quantitation of benzimidazolic and carbamate pesticides in fruit and juice samples using liquid chromatography with diode array detection, and of polycyclic aromatic hydrocarbons in water samples, in both cases in the presence of potential interferents using liquid chromatography with fluorescence spectral detection, thereby achieving the second-order advantage. The overall results seem to favor MCR-ALS over PARAFAC2, especially in the presence of potential interferents.

  5. [Preparation of an agglomerated ion chromatographic stationary phase with 2,3-ionene and its application in SO4(2-) analysis].

    Science.gov (United States)

    Wang, Muhua; Liu, Junwei; Huang, Zhongping; Zhang, Jiajie; Zhu, Yan

    2015-07-01

    The poly-electrolyte cation functional group of 2,3-ionene was synthesized with tetramethyl ethylenediamine and 1,3-dibromopropane as the raw materials. Multiporous polystyrene-divinylbenzene microsphere particles (PS-DVB) were produced by swelling method with polystyrene as seeds and sulfonated. Then the 2,3-ionene was bonded on the sulfonated multi-porous polystyrene-divinylbenzene microsphere particles by agglomeration to get the agglomerative ion-exchange stationary phase. After optimizing the synthetic conditions, the new stationary phase was characterized by the techniques including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and elemental analysis. The chromatographic column was packed by slurry method and applied in the analysis of SO4(2-) with a conductivity detector. SO4(2-) and other six common anions including F-, Cl-, NO2(-), Br-, NO3(-), PO4(3-), were separated and analyzed rapidly on the self-regulating chromatographic column within 8 min. The linear range was from 0.5 to 50 mg/L with correlation coefficient (r) of 0.9992. The LOD was 0.04 mg/L with S/N of 3. The relative standard deviations (RSDs, n = 6) were 2.4% and 3.1% for the peak area and retention time, respectively. The recoveries were between 99.2% and 101.8%. The retention times of SO4(2-) did not change significantly after long time use of the self-regulating chromatographic column. The self-regulating chromatographic column is suitable for the detection of SO4(2-) in complex matrix samples.

  6. Authentication of geographical origin of palm oil by chromatographic fingerprinting of triacylglycerols an partial least square-discriminant analysis

    NARCIS (Netherlands)

    Ruiz-Samblas, C.; Arrebola-Pascual, C.; Tres, A.; Ruth, van S.M.; Cuadros-Rodriquez, L.

    2013-01-01

    Main goals of the present work were to develop authentication models based on liquid and gas chromatographic fingerprinting of triacylglycerols (TAGs) from palm oil of different geographical origins in order to compare them. For this purpose, a set of palm oil samples were collected from different c

  7. Novel system for classifying chromatographic applications, exemplified by comprehensive two-dimensional gas chromatography and multivariate analysis

    NARCIS (Netherlands)

    Mispelaar, V.G. van; Janssen, H.G.; Tas, A.C.; Schoenmakers, P.J.

    2005-01-01

    For practical chromatographers it is extremely difficult to judge the merits and limitations of new technological developments. On the other hand, it is nearly impossible for those at the forefront of technology to judge the implications of their efforts for all specific applications of chromatograp

  8. Novel system for classifying chromatographic applications, exemplified by comprehensive two-dimensional gas chromatography and multivariate analysis

    NARCIS (Netherlands)

    Mispelaar, V.G. van; Janssen, H.G.; Tas, A.C.; Schoenmakers, P.J.

    2005-01-01

    For practical chromatographers it is extremely difficult to judge the merits and limitations of new technological developments. On the other hand, it is nearly impossible for those at the forefront of technology to judge the implications of their efforts for all specific applications of

  9. Analysis of failures of waterproofing cladding layers of terracotta tiles

    Directory of Open Access Journals (Sweden)

    Koláčný Milan

    2017-01-01

    Full Text Available The article is focused on one of the most important roof cladding layers – the waterproofing cladding layer of terracotta tiles. Its detailed analysis covers the main waterproofing cladding layers in terms of their material characteristics and installation methods. The article concludes by formulating principles for the correct design of the main waterproofing layer/construction.

  10. Chemometrics-assisted high performance liquid chromatography-diode array detection strategy to solve varying interfering patterns from different chromatographic columns and sample matrices for beverage analysis.

    Science.gov (United States)

    Yin, Xiao-Li; Wu, Hai-Long; Gu, Hui-Wen; Hu, Yong; Wang, Li; Xia, Hui; Xiang, Shou-Xia; Yu, Ru-Qin

    2016-02-26

    This work reports a chemometrics-assisted high performance liquid chromatography-diode array detection (HPLC-DAD) strategy to solve varying interfering patterns from different chromatographic columns and sample matrices for the rapid simultaneous determination of six synthetic colorants in five kinds of beverages with little sample pretreatment. The investigation was performed using two types of LC columns under the same elution conditions. Although analytes using different columns have different co-elution patterns that appear more seriously in complex backgrounds, all colorants were properly resolved by alternating trilinear decomposition (ATLD) method and accurate chromatographic elution profiles, spectral profiles as well as relative concentrations were obtained. The results were confirmed by those obtained from traditional HPLC-UV method at a particular wavelength and the results of both methods were consistent with each other. All results demonstrated that the proposed chemometrics-assisted HPLC-DAD method is accurate, economical and universal, and can be promisingly applied to solve varying interfering patterns from different chromatographic columns and sample matrices for the analysis of complex food samples.

  11. Qualitative and quantitative reversed-phase high performance liquid chromatographic analysis of glycoprotein hormones in the presence of a large excess of human serum albumin.

    Science.gov (United States)

    Almeida, B E; Oliveira, J E; Damiani, R; Dalmora, S L; Bartolini, P; Ribela, M T C P

    2012-04-07

    The present work describes reversed-phase high performance liquid chromatographic methodologies (RP-HPLC) for the qualitative and quantitative analysis of the human glycoprotein hormones thyrotropin (hTSH), follitropin (hFSH), choriogonadotropin (hCG) and lutropin (hLH) in the presence of a large excess (up to 250:1) of human serum albumin (HSA). Chromatographic profiles with a good separation between the hormone and HSA were obtained by using a C4 column and specific gradient elution conditions for each hormone. Parameters such as resolution factor, tailing factor and relative retention time, were determined, and are useful for the evaluation of the quality of the separation obtained between the active pharmaceutical ingredient and the excipient present in the final formulation. The potential of each method for quantification of both HSA and the hormone was also demonstrated. Besides furnishing chromatographic quantifications that can substitute for in vivo bioassays and animal use, the chromatograms also provide a direct panorama of the quality and heterogeneity of the protein of interest.

  12. Partial least squares model and design of experiments toward the analysis of the metabolome of Jatropha gossypifolia leaves: Extraction and chromatographic fingerprint optimization.

    Science.gov (United States)

    Pilon, Alan Cesar; Carnevale Neto, Fausto; Freire, Rafael Teixeira; Cardoso, Patrícia; Carneiro, Renato Lajarim; Da Silva Bolzani, Vanderlan; Castro-Gamboa, Ian

    2016-03-01

    A major challenge in metabolomic studies is how to extract and analyze an entire metabolome. So far, no single method was able to clearly complete this task in an efficient and reproducible way. In this work we proposed a sequential strategy for the extraction and chromatographic separation of metabolites from leaves Jatropha gossypifolia using a design of experiments and partial least square model. The effect of 14 different solvents on extraction process was evaluated and an optimized separation condition on liquid chromatography was estimated considering mobile phase composition and analysis time. The initial conditions of extraction using methanol and separation in 30 min between 5 and 100% water/methanol (1:1 v/v) with 0.1% of acetic acid, 20 μL sample volume, 3.0 mL min(-1) flow rate and 25°C column temperature led to 107 chromatographic peaks. After the optimization strategy using i-propanol/chloroform (1:1 v/v) for extraction, linear gradient elution of 60 min between 5 and 100% water/(acetonitrile/methanol 68:32 v/v with 0.1% of acetic acid), 30 μL sample volume, 2.0 mL min(-1) flow rate, and 30°C column temperature, we detected 140 chromatographic peaks, 30.84% more peaks compared to initial method. This is a reliable strategy using a limited number of experiments for metabolomics protocols.

  13. Second-order Data by Flow Injection Analysis with Spectrophotometric Diode-array Detection and Incorporated Gel-filtration Chromatographic Column

    DEFF Research Database (Denmark)

    Bechmann, Iben Ellegaard

    1997-01-01

    A flow injection analysis (FIA) system furnished with a gel-filtration chromatographic column and with photodiode-array detection was used for the generation of second-order data. The system presented is a model system in which the analytes are blue dextran, potassium hexacyanoferrate......(III) and heparin. It is shown that the rank of the involved sample data matrices corresponds to the number of chemical components present in the sample. The PARAFAC (parallel factor analysis) algorithm combined with multiple linear regression and the tri-PLS (tri-linear partial least-squares regression), which...

  14. Secondary metabolites isolation in natural products chemistry: comparison of two semipreparative chromatographic techniques (high pressure liquid chromatography and high performance thin-layer chromatography).

    Science.gov (United States)

    Do, Thi Kieu Tiên; Hadji-Minaglou, Francis; Antoniotti, Sylvain; Fernandez, Xavier

    2014-01-17

    Chemical investigations on secondary metabolites in natural products chemistry require efficient isolation techniques for characterization purpose as well as for the evaluation of their biological properties. In the case of phytochemical studies, the performance of the techniques is critical (resolution and yield) since the products generally present a narrow range of polarity and physicochemical properties. Several techniques are currently available, but HPLC (preparative and semipreparative) is the most widely used. To compare the performance of semipreparative HPLC and HPTLC for the isolation of secondary metabolites in different types of extracts, we have chosen carvone from spearmint essential oil (Mentha spicata L.), resveratrol from Fallopia multiflora (Thunb.) Haraldson, and rosmarinic acid from rosemary (Rosmarinus officinalis L.) extracts. The comparison was based on the chromatographic separation, the purity and quantity of isolated compounds, the solvent consumption, the duration and the cost of the isolation operations. The results showed that semipreparative HPTLC can in some case offer some advantages over conventional semipreparative HPLC. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Analysis of essential oils and fragrances with a new generation of highly inert gas chromatographic columns coated with ionic liquids.

    Science.gov (United States)

    Cagliero, Cecilia; Bicchi, Carlo; Cordero, Chiara; Liberto, Erica; Rubiolo, Patrizia; Sgorbini, Barbara

    2017-04-28

    In the fields of essential oils and fragrances, samples often consist of mixtures of compounds with similar structural and physical characteristics (e.g. mono- and sesquiterpenoids), whose correct identification closely depends on the synergic combination of chromatographic and mass spectral data. This sample complexity means that new GC stationary phases with different selectivities are continually being investigated. Ionic liquids (ILs) are of great interest as GC stationary phases in this field because of their selectivity (significantly different than that of currently phases) and their high temperature stability. A first generation of IL GC columns was found to be competitive when applied to these field, in terms of selectivity and efficiency, compared to conventional columns (polydimethylsiloxane, (e.g. OV-1), methyl-polysiloxane 5%-phenyl (e.g. SE-52), 7%-cyanopropyl, 7%-phenyl polysiloxane (e.g. OV-1701), and polyethylen glycol (e.g. PEG-20M). However, these columns showed significant activity towards polar or active analytes, which primarily affected their quantitative performance. A new generation of highly-inactive columns coated with three of the most widely-used ionic liquid GC stationary phases has recently been introduced; these phases are SLB-IL60i (1,12-di(tripropylphosphonium) dodecane bis(trifluoromethylsulfonyl) imide [NTf2], SLB-IL76i (tri-(tripropylphosphonium-hexanamido)-triethylamine [NTf2]), and SLB-IL111i (1,5-di (2,3-dimethyllimidazolium) pentane [NTf2]). This study carefully tested the new inert IL columns, in view of their routine application in the fragrance and essential oil fields. They were found to have unusually high selectivity, comparable to that of first-generation IL columns, while their inertness and efficiency were competitive with those of currently-used conventional columns. The IL column performance of first and second generations was compared, through the quali-quantitative analysis of components in a group of different

  16. Preprocessing of Oil Chromatographic Signal Based on Wavelet Transform Packet Analysis%基于小波包分析的油色谱信号预处理

    Institute of Scientific and Technical Information of China (English)

    曹玲燕; 胡铟; 贺枫

    2014-01-01

    Considering instability and incomplete deduction of the chromatographic baseline of transformer oil on-line monitoring system,a wavelet packet analysis-based baseline chromatographic signal reprocessing meth-od was proposed,which having wavelet packet used to implement multi-resolution decomposition and to deduct both low and high-frequency disturbance signals so as to obtain a chromatographic signal needed.The experi-mental results show that compared to the traditional wavelet transform,the wavelet packet analysis can do bet-ter in signal processing,reducing baseline interference and improving analysis precision and model stability.%针对变压器油色谱在线监测系统在现场使用中存在的色谱基线不稳定、扣除不完全等问题,提出了基于小波包分析的色谱信号预处理。该方法通过小波包对信号进行多分辨率分解,扣除部分干扰高、低频信号,得到所需要的色谱信号。实验结果表明:将小波包应用到色谱信号数据预处理中,相对于传统小波变换能更细致地进行信号分析,较好地进行色谱基线的扣除,减少基线对色谱信号的干扰,从而有效提高油色谱在线监测系统的分析精度和模型稳定性。

  17. Economic analysis of uricase production under uncertainty: Contrast of chromatographic purification and aqueous two-phase extraction (with and without PEG recycle).

    Science.gov (United States)

    Torres-Acosta, Mario A; Aguilar-Yáñez, José M; Rito-Palomares, Marco; Titchener-Hooker, Nigel J

    2016-01-01

    Uricase is the enzyme responsible for the breakdown of uric acid, the key molecule leading to gout in humans, into allantoin, but it is absent in humans. It has been produced as a PEGylated pharmaceutical where the purification is performed through three sequential chromatographic columns. More recently an aqueous two-phase system (ATPS) was reported that could recover Uricase with high yield and purity. Although the use of ATPS can decrease cost and time, it also generates a large amount of waste. The ability, therefore, to recycle key components of ATPS is of interest. Economic modelling is a powerful tool that allows the bioprocess engineer to compare possible outcomes and find areas where further research or optimization might be required without recourse to extensive experiments and time. This research provides an economic analysis using the commercial software BioSolve of the strategies for Uricase production: chromatographic and ATPS, and includes a third bioprocess that uses material recycling. The key parameters that affect the process the most were located via a sensitivity analysis and evaluated with a Monte Carlo analysis. Results show that ATPS is far less expensive than chromatography, but that there is an area where the cost of production of both bioprocesses overlap. Furthermore, recycling does not impact the cost of production. This study serves to provide a framework for the economic analysis of Uricase production using alternative techniques.

  18. Suspect screening of large numbers of emerging contaminants in environmental waters using artificial neural networks for chromatographic retention time prediction and high resolution mass spectrometry data analysis.

    Science.gov (United States)

    Bade, Richard; Bijlsma, Lubertus; Miller, Thomas H; Barron, Leon P; Sancho, Juan Vicente; Hernández, Felix

    2015-12-15

    The recent development of broad-scope high resolution mass spectrometry (HRMS) screening methods has resulted in a much improved capability for new compound identification in environmental samples. However, positive identifications at the ng/L concentration level rely on analytical reference standards for chromatographic retention time (tR) and mass spectral comparisons. Chromatographic tR prediction can play a role in increasing confidence in suspect screening efforts for new compounds in the environment, especially when standards are not available, but reliable methods are lacking. The current work focuses on the development of artificial neural networks (ANNs) for tR prediction in gradient reversed-phase liquid chromatography and applied along with HRMS data to suspect screening of wastewater and environmental surface water samples. Based on a compound tR dataset of >500 compounds, an optimized 4-layer back-propagation multi-layer perceptron model enabled predictions for 85% of all compounds to within 2min of their measured tR for training (n=344) and verification (n=100) datasets. To evaluate the ANN ability for generalization to new data, the model was further tested using 100 randomly selected compounds and revealed 95% prediction accuracy within the 2-minute elution interval. Given the increasing concern on the presence of drug metabolites and other transformation products (TPs) in the aquatic environment, the model was applied along with HRMS data for preliminary identification of pharmaceutically-related compounds in real samples. Examples of compounds where reference standards were subsequently acquired and later confirmed are also presented. To our knowledge, this work presents for the first time, the successful application of an accurate retention time predictor and HRMS data-mining using the largest number of compounds to preliminarily identify new or emerging contaminants in wastewater and surface waters.

  19. Two-dimensional thin-layer chromatography in the analysis of secondary plant metabolites.

    Science.gov (United States)

    Cieśla, Lukasz; Waksmundzka-Hajnos, Monika

    2009-02-13

    Drugs, derived from medicinal plants, have been enjoying a renaissance in the last years. It is due to a great pharmacological potential of herbal drugs, as many natural compounds have been found to exhibit biological activity of wide spectrum. The introduction of whole plants, plant extracts, or isolated natural compounds has led to the need to create the analytical methods suitable for their analysis. The identification of isolated substances is relatively an easy task, but the analysis of plant extracts causes a lot of problems, as they are usually very complex mixtures. Chromatographic methods are one of the most popular techniques applied in the analysis of natural mixtures. Unfortunately the separation power of traditional, one-dimensional techniques, is usually inadequate for separation of more complex samples. In such a case the use of multidimensional chromatography is advised. Planar chromatography gives the possibility of performing two-dimensional separations with the use of one adsorbent with two different eluents or by using bilayer plates or graft thin-layer chromatography (TLC) technique; combinations of different multidimensional techniques are also possible. In this paper, multidimensional planar chromatographic methods, commonly applied in the analysis of natural compounds, were reviewed. A detailed information is given on the methodology of performing two-dimensional separations on one adsorbent, on bilayer plates, with the use of graft TLC and hyphenated methods. General aspects of multidimensionality in liquid chromatography are also described. Finally a reader will find a description of variable two-dimensional methods applied in the analysis of compounds, most commonly encountered in plant extracts. This paper is aimed to draw attention to the potential of two-dimensional planar chromatography in the field of phytochemistry. It may be useful for those who are interested in achieving successful separations of multicomponent mixtures by means

  20. Fresnel analysis of Kretschmann geometry with a uniaxial crystal layer on a three-layered film

    Directory of Open Access Journals (Sweden)

    Yu-Ju Hung

    2016-04-01

    Full Text Available The use of total internal reflection within the prism coupling scheme is a simple approach to the generation of surface plasmon polariton waves on a metal/dielectric interface. Unfortunately, an anisotropic layer on a metallic film complicates the derivation of resonance angle. In this study, we present clear Fresnel analysis of a liquid crystal film on a metal surface. Few current simulation packages enable the analysis of multiple layers with a single anisotropic layer. The proposed formulation process is applicable to multi-layered structures.

  1. Evaluation of the Influence of Sulfur-Fumigated Paeoniae Radix Alba on the Quality of Si Wu Tang by Chromatographic and Chemometric Analysis.

    Science.gov (United States)

    Pei, Ke; Cai, Hao; Duan, Yu; Qiao, Feng-Xian; Tu, Si-Cong; Liu, Xiao; Wang, Xiao-Li; Song, Xiao-Qing; Fan, Kai-Lei; Cai, Bao-Chang

    2016-01-01

    An accurate and reliable method of high-performance liquid chromatographic fingerprint combining with multi-ingredient determination was developed and validated to evaluate the influence of sulfur-fumigated Paeoniae Radix Alba on the quality and chemical constituents of Si Wu Tang. Multivariate data analysis including hierarchical cluster analysis and principal component analysis, which integrated with high-performance liquid chromatographic fingerprint and multi-ingredient determination, was employed to evaluate Si Wu Tang in a more objective and scientific way. Interestingly, in this paper, a total of 37 and 36 peaks were marked as common peaks in ten batches of Si Wu Tang containing sun-dried Paeoniae Radix Alba and ten batches of Si Wu Tang containing sulfur-fumigated Paeoniae Radix Alba, respectively, which indicated the changed fingerprint profile of Si Wu Tang when containing sulfur-fumigated herb. Furthermore, the results of simultaneous determination for multiple ingredients showed that the contents of albiflorin and paeoniflorin decreased significantly (P < 0.01) and the contents of gallic acid and Z-ligustilide decreased to some extent at the same time when Si Wu Tang contained sulfur-fumigated Paeoniae Radix Alba. Therefore, sulfur-fumigation processing may have great influence on the quality of Chinese herbal prescription.

  2. Effect of the Silanization Conditions on Chromatographic Behavior of an Open-tubular Capillary Column Coated with a Modified Silica-gel Thin Layer

    OpenAIRE

    Yusuke, Nakano; Shinya, Kitagawa; Kanji, Miyabe; Takao, Tsuda

    2005-01-01

    The performance of an open-tubular capillary column coated with a modified silica-gel thin layer was investigated, particularly concerning the effect of the silanization process on it. Although the increase in the octadecyltriethoxysilane (ODTES) concentration in the silanization process could enhance the retention factor of naphthalene, its theoretical plate number was significantly reduced (ODTES, 5 to 50%; k, 0.2 to 4.3; N, 79600 to 2600 m-1). Namely, the increase in the retention factor w...

  3. Chromatographic fingerprint analysis of Bupleuri Radix by HPLC-ELSD%柴胡的HPLC-ELSD指纹图谱研究

    Institute of Scientific and Technical Information of China (English)

    周勇; 王延亮; 马志桥; 王邠; 梁鸿; 赵玉英; 张庆英

    2013-01-01

    To facilitate the species identification and quality assessment of Chaihu (Bupleuri Radix),a simple and valid chromatographic fingerprint method was developed.The method uses high-performance liquid chromatography coupled with evaporative light scattering detector (HPLC-ELSD) and the data analysis is assisted by professional analytical software recommended by the State Food and Drug Administration (SFDA).The results indicate that Nan Chaihu raw materials and Chaihu decoction pieces vary markedly in chemical quality,while Bei Chaihu raw materials are relatively more stable.Furthermore,it is obvious that Nan Chaihu is chemically very different from Bei Chaihu,suggesting that Nan Chaihu may not be suitable for medicinal use.In addition,the obvious differences between the chromatograms of decoction pieces and raw materials,especially the peaks between 30 and 40 min and after 45 min,indicate possible effects of the processing procedures on the chemicals.By analyzing the fingerprints of all samples,12 main saponin-like fingerprint peaks,of which at least three are characteristic peaks of saikosaponins a,c,and d,are proposed to be considered for further characterization and quality evaluation of Chaihu.%本文建立了一种简单、有效的柴胡药材的高效液相色谱-蒸发光散射(HPLC-ELSD)指纹图谱方法,并对不同产地和不同品种的柴胡药材及其饮片进行了系统评价.研究结果显示南柴胡药材和市售柴胡饮片的化学成分变化较大,而北柴胡药材的化学成分则相对稳定,且南柴胡药材与北柴胡药材化学成分差别明显,提示南柴胡药材作为柴胡应用要谨慎.另外与柴胡药材相比,柴胡饮片的指纹图谱也发生了变化,尤其是保留时间在30-40分钟之间和45分钟之后色谱峰变化尤为明显,提示在炮制过程中可能发生了化学成分的变化.最终本文确定了柴胡中12个主要皂苷类成分的色谱指纹峰,并建议柴胡皂苷a、c和d为其基本特

  4. Gas chromatographic analysis of dimethyltryptamine and beta-carboline alkaloids in ayahuasca, an Amazonian psychoactive plant beverage.

    Science.gov (United States)

    Pires, Ana Paula Salum; De Oliveira, Carolina Dizioli Rodrigues; Moura, Sidnei; Dörr, Felipe Augusto; Silva, Wagner Abreu E; Yonamine, Mauricio

    2009-01-01

    Ayahuasca is obtained by infusing the pounded stems of Banisteriopsis caapi in combination with the leaves of Psychotria viridis. P. viridis is rich in the psychedelic indole N,N-dimethyltryptamine, whereas B. caapi contains substantial amounts of beta-carboline alkaloids, mainly harmine, harmaline and tetrahydroharmine, which are monoamine-oxidase inhibitors. Because of differences in composition in ayahuasca preparations, a method to measure their main active constituents is needed. To develop a gas chromatographic method for the simultaneous determination of dimethyltryptamine and the main beta-carbolines found in ayahuasca preparations. The alkaloids were extracted by means of solid phase extraction (C(18)) and detected by gas chromatography with nitrogen/phosphorous detector. The lower limit of quantification (LLOQ) was 0.02 mg/mL for all analytes. The calibration curves were linear over a concentration range of 0.02-4.0 mg/mL (r(2 )> 0.99). The method was also precise (RSD < 10%). A simple gas chromatographic method to determine the main alkaloids found in ayahuasca was developed and validated. The method can be useful to estimate administered doses in animals and humans for further pharmacological and toxicological investigations of ayahuasca. Copyright (c) 2009 John Wiley & Sons, Ltd.

  5. [The rapid analysis of polychlorinated quaterphenyls in blood using different diameter capillary column with the high-resolution gas chromatograph high-resolution mass spectrometer].

    Science.gov (United States)

    Yasutake, Daisuke; Ashizuka, Yuki; Hori, Tsuguhide; Kurokawa, Youichi; Kajiwara, Jumboku; Hirata, Teruaki; Ishiguro, Yasuhisa; Iida, Takao; Uchi, Hiroshi; Furue, Masutaka

    2011-04-01

    The polychlorinated quaterphenyl (PCQ) concentrations in blood are important discriminative parameters in yusho patient. In this study, a rapid analytical method for PCQ using different diameter capillary column (rapid-Rtx65TG) with high-resolution gas chromatograph high-resolution mass spectrometer (HRGC/HRMS) instead of the gas chromatograph electron capture detector (ECD/GC) was developed. Using different diameter capillary columns, the analysis time of the HRGC/HRMS was drastically shortened, and the detection sensitivity was improved. In the rapid-Rtx65TG column, a small-bore capillary column (length 1m, I.D. 0.1mm) was connected with the inlet side of the GC, and behind that column, a large-bore capillary column (length 15mm, I.D. 0.53mm) for octadecachloroquaterphenyl (ODCQ) analysis was connected. In the HRGC/HRMS measurement of ODCQ by the rapid-Rtx65TG column, the minimum limit of detection for the apparatus was 0.4 pg, and the minimum limit of determination for the blood was 0.008 ppb. On ECD/GC in the conventional method and HRGC/HRMS in this study, the PCQ concentration in blood including yusho patients and yusho suspected persons was almost equivalent.

  6. Improved method for the extraction and chromatographic analysis on a fused-core column of ellagitannins found in oak-aged wine.

    Science.gov (United States)

    Navarro, María; Kontoudakis, Nikolaos; Canals, Joan Miquel; García-Romero, Esteban; Gómez-Alonso, Sergio; Zamora, Fernando; Hermosín-Gutiérrez, Isidro

    2017-07-01

    A new method for the analysis of ellagitannins observed in oak-aged wine is proposed, exhibiting interesting advantages with regard to previously reported analytical methods. The necessary extraction of ellagitannins from wine was simplified to a single step of solid phase extraction (SPE) using size exclusion chromatography with Sephadex LH-20 without the need for any previous SPE of phenolic compounds using reversed-phase materials. The quantitative recovery of wine ellagitannins requires a combined elution with methanol and ethyl acetate, especially for increasing the recovery of the less polar acutissimins. The chromatographic method was performed using a fused-core C18 column, thereby avoiding the coelution of main ellagitannins, such as vescalagin and roburin E. However, the very polar ellagitannins, namely, the roburins A, B and C, still partially coeluted, and their quantification was assisted by the MS detector. This methodology also enabled the analysis of free gallic and ellagic acids in the same chromatographic run. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Comparative analysis of radical scavenging and antioxidant activity of phenolic compounds present in everyday use spice plants by means of spectrophotometric and chromatographic methods.

    Science.gov (United States)

    Stankevičius, Mantas; Akuņeca, Ieva; Jãkobsone, Ida; Maruška, Audrius

    2011-06-01

    Comparative analysis of radical scavenging and antioxidant activities of phenolic compounds present in everyday use spice plants was carried out by means of spectrophotometric and chromatographic methods. Six spice plant samples, namely onion (Allium cepa), parsley (Petroselinum crispum) roots and leaves, celery (Apium graveolens) roots and leaves and leaves of dill (Anethum graveolens) were analyzed. Total amount of phenolic compounds and radical scavenging activity (RSA) was the highest in celery leaves and dill extracts and was the lowest in celery roots. Comparing commonly used spectrophotometric analysis of 2,2-diphenyl-1-picrylhydrazyl (DPPH) RSA of extracts with the results obtained using reversed-phase chromatographic separation with on-line post-column radical scavenging reaction detection, good correlation was obtained (R(2)=0.848). Studies using HPLC system with electrochemical detector showed that bioactive phytochemicals can be separated and antioxidant activities of individual compounds evaluated without the need of a complex HPLC system with reaction detector. The results obtained using electrochemical detection correlate with the RSA assayed using spectrophotometric method (R(2)=0.893).

  8. Effect of the silanization conditions on chromatographic behavior of an open-tubular capillary column coated with a modified silica-gel thin layer.

    Science.gov (United States)

    Nakano, Yusuke; Kitagawa, Shinya; Miyabe, Kanji; Tsuda, Takao

    2005-10-01

    The performance of an open-tubular capillary column coated with a modified silica-gel thin layer was investigated, particularly concerning the effect of the silanization process on it. Although the increase in the octadecyltriethoxysilane (ODTES) concentration in the silanization process could enhance the retention factor of naphthalene, its theoretical plate number was significantly reduced (ODTES, 5 to 50%; k, 0.2 to 4.3; N, 79600 to 2600 m(-1)). Namely, the increase in the retention factor was accompanied by a decrease in the theoretical plate number. A similar phenomenon was also observed when octadecyldimethylchlorosilane (ODCS) was used as the silanization regent. However, increases in both the retention factor and the theoretical plate number could be achieved (sample, naphthalene; k, 0.05 to 0.09; N, 149000 to 220000 m(-1)) by a NaOH treatment to the fabricated thin porous silica-gel layer before silanization with ODCS. The electrochromatographic separation of proteins and peptides by using the NaOH-treated column could obtain more peaks than electrophoretic separation.

  9. Thin Layer Chromatographic Study of Bauxite and Quantitative Estimation of Co-Existing Al3+, Fe2+ and Ti4+%薄层色谱法测定铝土矿中的主成分及其共存离子Al3+,Fe2+和Ti4+

    Institute of Scientific and Technical Information of China (English)

    MOHAMED NAJAR P A; JEURKAR J U; RAMANA RAO K V

    2005-01-01

    Thin layer chromatography in combination with spectrophotometry and titrimetry has been used to evaluate chromatographic characteristics of bauxite constituents. The retention behaviors of four major constituents (Al3+, Fe2+, Ti4+, Si4+) in bauxite mineral have been examined on plain and modified layers of silica gel G, silica gel H and cellulose with mobile phases containing aqueous sodium chloride, formic acid and hydrochloric acid. Ternary separation of Al-Fe-Ti was achieved on chromatographic plates made of silica gel H. The Ph effect and presence of impurity elements in samples, nature of stationary phases on the ternary separation and detection limits of bauxite constituents were studied. Silicon in bauxite was detected on cellulose plates. Quantitative determinations of Al3+, Fe2+ and Ti4+ on silica gel H impregnated with sodium formate layers were achieved by titrimetry and spectrophotometry.

  10. Quality analysis of commercial samples of Ziziphi spinosae semen (suanzaoren by means of chromatographic fingerprinting assisted by principal component analysis

    Directory of Open Access Journals (Sweden)

    Shuai Sun

    2014-06-01

    Full Text Available Due to the scarcity of resources of Ziziphi spinosae semen (ZSS, many inferior goods and even adulterants are generally found in medicine markets. To strengthen the quality control, HPLC fingerprint common pattern established in this paper showed three main bioactive compounds in one chromatogram simultaneously. Principal component analysis based on DAD signals could discriminate adulterants and inferiorities. Principal component analysis indicated that all samples could be mainly regrouped into two main clusters according to the first principal component (PC1, redefined as Vicenin II and the second principal component (PC2, redefined as zizyphusine. PC1 and PC2 could explain 91.42% of the variance. Content of zizyphusine fluctuated more greatly than that of spinosin, and this result was also confirmed by the HPTLC result. Samples with low content of jujubosides and two common adulterants could not be used equivalently with authenticated ones in clinic, while one reference standard extract could substitute the crude drug in pharmaceutical production. Giving special consideration to the well-known bioactive saponins but with low response by end absorption, a fast and cheap HPTLC method for quality control of ZSS was developed and the result obtained was commensurate well with that of HPLC analysis. Samples having similar fingerprints to HPTLC common pattern targeting at saponins could be regarded as authenticated ones. This work provided a faster and cheaper way for quality control of ZSS and laid foundation for establishing a more effective quality control method for ZSS.

  11. Qualitative and quantitative analysis of specific polysaccharides in Dendrobium huoshanense by using saccharide mapping and chromatographic methods.

    Science.gov (United States)

    Deng, Yong; Chen, Ling-Xiao; Han, Bang-Xing; Wu, Ding-Tao; Cheong, Kit-Leong; Chen, Nai-Fu; Zhao, Jing; Li, Shao-Ping

    2016-09-10

    Qualitative and quantitative analysis of specific polysaccharides from ten batches of Dendrobium huoshanense were performed using high performance size exclusion chromatography coupled with multi-angle laser light scattering and refractive index detector (HPSEC-MALLS-RID), gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) and saccharide mapping based on polysaccharides analysis by using carbohydrate gel electrophoresis (PACE) and high performance thin layer chromatography (HPTLC). Results showed that molecular weights, the radius of gyrations, and contents of specific polysaccharides in D. huoshanense were ranging from 1.16×10(5) to 2.17×10(5)Da, 38.8 to 52.1nm, and 9.9% to 19.9%, respectively. Furthermore, the main monosaccharide compositions were Man and Glc. Indeed, the main glycosidic linkages were β-1,4-Manp and β-1,4-Glcp, and substituted with acetyl groups at O-2 and O-3 of 1,4-linked Manp. Moreover, results showed that PACE and HPTLC fingerprints of partial acidic and enzymatic hydrolysates of specific polysaccharides were similar, which are helpful to better understand the specific polysaccharides in D. huoshanense and beneficial to improve their quality control. These approaches could also be routinely used for quality control of polysaccharides in other medicinal plants. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Supercharging Reagent for Enhanced Liquid Chromatographic Separation and Charging of Sialylated and High-Molecular-Weight Glycopeptides for NanoHPLC-ESI-MS/MS Analysis.

    Science.gov (United States)

    Lin, Chia-Wei; Haeuptle, Micha A; Aebi, Markus

    2016-09-01

    Recent developments in proteomic techniques have led to the development of mass spectrometry (MS)-based methods to characterize site-specific glycosylation of proteins. However, appropriate analytical tools to characterize acidic and high-molecular-weight (hMW) glycopeptides are still lacking. In this study, we demonstrate that the addition of supercharging reagent, m-nitrobenzyl alcohol (m-NBA), into mobile phases greatly facilitates the analysis of acidic and hMW glycopeptides. Using commercial glycoproteins, we demonstrated that in the presence of m-NBA the charge state of sialylated glycopeptides increased and the chromatographic separation of neutral and acidic glycopeptides revealed a remarkable improvement. Next, we applied this system to the characterization of a glycoconjugate vaccine candidate consisting of a genetically detoxified exotoxin A of Pseudomonas aeruginosa covalently linked to Shigella flexneri type 2a O-antigen (Sf2E) produced by engineered Escherichia coli. The addition of m-NBA, allowed us to identify peptides with glycan chains of unprecedented size, up to 20 repeat units (98 monosaccharides). Our results indicated that incorporation of m-NBA into reversed-phase liquid chromatography (LC) solvents improves sensitivity, charging, and chromatographic resolution for acidic and hMW glycopeptides.

  13. Electrospun cellulose acetate nanofibers as thin layer chromatographic media for eco-friendly screening of steroids adulterated in traditional medicine and nutraceutical products.

    Science.gov (United States)

    Rojanarata, Theerasak; Plianwong, Samarwadee; Su-uta, Kosit; Opanasopit, Praneet; Ngawhirunpat, Tanasait

    2013-10-15

    Nanofibers fabricated from cheap, naturally derived biopolymer, namely cellulose acetate via facile electrospinning technique were successfully applied for the first time to use as separation media for thin layer chromatography (TLC). From the optimization studies, uniform, bead-free nanofibers with good adherence to the backing plates were obtained by electrospinning 17% (w/v) cellulose acetate solution prepared in acetone/N,N-dimethylacetamide (2:1, v-v), using a feed rate of 0.6 mL/h and an electrostatic field strength of 17.5 kV/15 cm for 4h. The nanofibers exhibited reversed phase characteristics, thereby offering the possibility to use simple, polar and more environmental friendly mixtures of water and alcohols as mobile phase. In this work, the application of the fabricated fibers was illustrated by using them combined with the optimal mobile phase e.g. ethanol/water (40:60, v-v) for the screening of steroids adulterated in traditional medicine and nutraceutical products. Due to the satisfactory separation performance, electrospun cellulose acetate nanofibers were shown to be an efficient alternative for TLC media and could be potentially used for the development of green and facile analytical methods. © 2013 Elsevier B.V. All rights reserved.

  14. Two-dimensional thin-layer chromatography with adsorbent gradient as a method of chromatographic fingerprinting of furanocoumarins for distinguishing selected varieties and forms of Heracleum spp.

    Science.gov (United States)

    Cieśla, Lukasz; Bogucka-Kocka, Anna; Hajnos, Michał; Petruczynik, Anna; Waksmundzka-Hajnos, Monika

    2008-10-17

    There are a lot of taxonomic classifications of the genus Heracleum, and many authors indicate they need revision. Morphological identification is difficult to perform, as there are only few characteristic differences between each Heracleum species, varieties and forms. Furanocoumarins are characteristic compounds for the Apiaceae family, and they can be found in the whole genus in large quantities. Despite this fact, it is difficult to use the furanocoumarin profiles of plants, for their discrimination, as furanocoumarins are difficult to separate, due to their similar chemical structures and physicochemical properties. In this paper, a new, simple method is proposed for the discrimination of selected species, varieties and forms of the genus Heracleum. Thin-layer chromatography (TLC) with an adsorbent gradient (unmodified silica gel+octadecylsilica wettable with water) enables complete separation of the structural analogues. The proposed method gives the possibility to distinguish selected species, varieties and forms of the Heracleum genus, as they produce distinctive furanocoumarin fingerprints. The method is characterised by high specificity, precision, reproducibility and stability values. It is for the first time that graft TLC is used for constructing fingerprints of herbs. The complete separation of ten structural analogues, by combining gradient TLC with the unidimensional multiple development technique, has not been reported yet.

  15. Chemometric analysis of chromatographic fingerprints shows potential of Cyclopia maculata (Andrews) Kies for production of standardized extracts with high xanthone content.

    Science.gov (United States)

    Schulze, Alexandra E; de Beer, Dalene; de Villiers, André; Manley, Marena; Joubert, Elizabeth

    2014-10-29

    Cyclopia species are used for the production of honeybush tea and food ingredient extracts associated with many health benefits. A species-specific high-performance liquid chromatography (HPLC) method for Cyclopia maculata, developed and validated, allowed quantification of the major compounds in extracts from "unfermented" and fermented C. maculata. Two xanthones were tentatively identified for the first time in a Cyclopia species, whereas an additional four compounds were tentatively identified for the first time in C. maculata. "Fermentation" (oxidation) decreased the content of all compounds, with the exception of vicenin-2. Similarity analysis of the chromatographic fingerprints of unfermented C. maculata aqueous extracts showed extremely low variation (r ≥ 0.97) between samples. Some differences between wild-harvested and cultivated seedling plants were, however, demonstrated using principal component analysis. Quantitative data of selected compounds confirmed the low level of variation, making this Cyclopia species ideal for the production of standardized food ingredient extracts.

  16. Characterisation of organic and conventional sweet basil leaves using chromatographic and flow-injection mass spectrometric (FIMS) fingerprints combined with principal component analysis.

    Science.gov (United States)

    Lu, Yingjian; Gao, Boyan; Chen, Pei; Charles, Denys; Yu, Liangli Lucy

    2014-07-01

    Sweet basil, Ocimum basilicum, is one of the most important and wildly used spices and has been shown to have antioxidant, antibacterial, and anti-diarrheal activities. In this study, high performance liquid chromatographic (HPLC) and flow-injection mass spectrometric (FIMS) fingerprinting techniques were used to differentiate organic and conventional sweet basil leaf samples. Principal component analysis (PCA) of the fingerprints indicated that both HPLC and FIMS fingerprints could effectively detect the chemical differences in the organic and conventional sweet basil leaf samples. This study suggested that the organic basil sample contained greater concentrations of almost all the major compounds than its conventional counterpart on a per same botanical weight basis. The FIMS method was able to rapidly differentiate the organic and conventional sweet basil leaf samples (1min analysis time), whereas the HPLC fingerprints provided more information about the chemical composition of the basil samples with a longer analytical time.

  17. Analysis and Processing of Total Descending No.1 Main Transformer Chromatographic Abnormality%总降1号主变色谱异常的分析与处理

    Institute of Scientific and Technical Information of China (English)

    袁健

    2015-01-01

    Based on the analysis and processing of power transformer oil chromatographic abnormality, this paper puts forward the methods to prevent similar failure of similar equipment. By chromatographic analysis results it is showed that after processing transformer oil meets operation requirements.%通过对一例电力变压器油色谱异常的分析和处理,提出了预防同类设备类似故障的方法。由色谱分析结果表明,故障处理后变压器油符合运行要求。

  18. Applications of gas chromatographic analysis system on sulphur Claus apparatus%气相色谱分析系统在硫磺Claus装置上的应用

    Institute of Scientific and Technical Information of China (English)

    刘军华

    2011-01-01

    The characteristics and online applications of gas chromatographic analysis system in the determination of sulfuric acid gas raw material are described. Properly selecting sampling and sample pretreatment systems according to the characteristics of the acid gas can solve the problem of long-term running of gas chromatographic analysis system in the determination of high concentration HZS.%根据酸性气特点设计取样及样品预处理系统,保证气相色谱系统的长周期运行问题.

  19. Chromatographic and Related Reactors.

    Science.gov (United States)

    1988-01-07

    special information about effects of surface heteroge- neity in the methanation reaction. Studies of an efficient multicolumn assembly for measuring...of organic basic catalysts such as pyridine and 4-methylpicoline. It was demonstrated that the chromatographic reactor gave special information about...Programmed Reaction to obtain special information about surface heterogeneity in the methanation reaction. Advantages of stopped flow over steady state

  20. Investigations on some metabolites of Tecoma stans Juss. callus tissue. Part II. Chromatographical analysis of alkaloid and quinone compounds

    Directory of Open Access Journals (Sweden)

    Barbara Dohnal

    2015-01-01

    Full Text Available Tecoma stans Juss. callus tissue grown on Murashige-Mei Lie Lin (M-L and Murashige-Skoog (RT-k medium supplemented with Tecoma alkaloid precursors like lysine, mevalonic acid lactone and quinolinic acid, were investigated for their alkaloid content by thin-layer (TLC and paper (PC chromatography methods. The results were compared with those obtained by parallel analysis of greenhouse plant leaves. Seven alkaloid spots were detected in the leaf extracts, namely: actinidine, 4-noractinidine, boschniakine, tecomanine, two spots of skytanthine derivatives and one unidentified spot. Only l spot corresponding to skytanthine derivatives appeard in the extracts of callus tissues cultured on basal M-L medium or supplemented with lysine or mevalonic acid lactone. However, 3 alkaloid spots were revealed in extracts of homogeneous parenchyma-like callus tissues obtained o-n, RT-k medium. Beside the skytanthine derivatives rnentioned above, actinidine and tecomanine were identified, and moreover, in callus tissues growing on the same medium (RT-k supplemented with quinolinic acid, boschniakine was found. It was found that T. stans leaves as well as callus tissues cultured on RT-k medium contained traces of lapachol and another quinone-type compound.

  1. Vibrational Spectroscopy of Chromatographic Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jeanne E. Pemberton

    2011-03-10

    Chromatographic separations play a central role in DOE-supported fundamental research related to energy, biological systems, the environment, and nuclear science. The overall portfolio of research activities in the Separations and Analysis Program within the DOE Office of Basic Energy Sciences includes support for activities designed to develop a molecular-level understanding of the chemical processes that underlie separations for both large-scale and analytical-scale purposes. The research effort funded by this grant award was a continuation of DOE-supported research to develop vibrational spectroscopic methods to characterize the interfacial details of separations processes at a molecular level.

  2. Thermal analysis of thin layer boilover

    Energy Technology Data Exchange (ETDEWEB)

    Kozanoglu, Bulent [Universidad de las Americas, Puebla (Mexico); Mechanical Engineering Department, Cholula, Puebla (Mexico); Ferrero, Fabio; Munoz, Miguel; Arnaldos, Josep; Casal, Joaquim [Universitat Politecnica de Catalunya, Barcelona (Spain)

    2008-10-15

    A mathematical model is developed to simulate the thin layer boilover phenomenon. This model takes into account convective currents as well as conduction and radiation absorption through the fuel layer and is resolved numerically employing a scheme of Runge-Kutta, combined with the numerical method of lines. Solutions of the model showed a good agreement with the experimental data, both from this work and by other authors, demonstrating the importance of the convective currents. The model provided velocities of these currents, of the same order of magnitude as the values reported in the technical literature. Thickness of the remaining fuel and the interface temperature are correctly calculated by the model, allowing the prediction of the time required for the boilover to start. (orig.)

  3. Analysis of the Younger Dryas Impact Layer

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Richard B.; West, Allen; Revay, Zsolt; Hagstrum, Jonathon T,; Belgya, Thomas; Hee, Shane S. Que; Smith, Alan R.

    2010-02-27

    We have uncovered a thin layer of magnetic grains and microspherules, carbon spherules, and glass-like carbon at nine sites across North America, a site in Belgium, and throughout the rims of 16 Carolina Bays. It is consistent with the ejecta layer from an impact event and has been dated to 12.9 ka BP coinciding with the onset of Younger Dryas (YD) cooling and widespread megafaunal extinctions in North America. At many locations the impact layer is directly below a black mat marking the sudden disappearance of the megafauna and Clovis people. The distribution pattern of the Younger Dryas boundary (YDB) ejecta layer is consistent with an impact near the Great Lakes that deposited terrestrial-like ejecta near the impact site and unusual, titanium-rich projectile-like ejecta further away. High water content associated with the ejecta, up to 28 at. percent hydrogen (H), suggests the impact occurred over the Laurentide Ice Sheet. YDB microspherules and magnetic grains are highly enriched in TiO{sub 2}. Magnetic grains from several sites are enriched in iridium (Ir), up to 117 ppb. The TiO{sub 2}/FeO, K/Th, TiO{sub 2}/Zr, Al{sub 2}O{sub 3}/FeO+MgO, CaO/Al{sub 2}O{sub 3}, REE/ chondrite, FeO/MnO ratios and SiO{sub 2}, Na{sub 2}O, K{sub 2}O, Cr{sub 2}O{sub 3}, Ni, Co, U, Th and other trace element abundances are inconsistent with all terrestrial and extraterrestrial (ET) sources except for KREEP, a lunar igneous rock rich in potassium (K), rare-earth elements (REE), phosphorus (P), and other incompatible elements including U and Th. Normal Fe, Ti, and {sup 238}U/{sup 235}U isotopic abundances were found in the magnetic grains, but {sup 234}U was enriched over equilibrium values by 50 percent in Murray Springs and by 130 percent in Belgium. 40K abundance is enriched by up to 100 percent in YDB sediments and Clovis chert artifacts. Highly vesicular carbon spherules containing nanodiamonds, glass-like carbon, charcoal and soot found in large quantities in the YDB layer are

  4. Liquid chromatographic determination of the glycoalkaloids alpha-solanine and alpha-chaconine in potato tubers: NMKL Interlaboratory Study. Nordic Committee on Food Analysis.

    Science.gov (United States)

    Hellenäs, K E; Branzell, C

    1997-01-01

    Twelve laboratories participated in a collaborative study to evaluate precision parameters of a liquid chromatographic method for analysis of the glycoalkaloids alpha-solanine and alpha-chaconine in potato tubers. Samples consisted of frozen potato tuber homogenates distributed as 3 blind duplicates and 3 split-level pairs. The analytical method included aqueous extraction, workup on disposable solid-phase extraction cartridges, and reversed-phase chromatography with photometric detection at 202 nm. Results for alpha-solanine and alpha-chaconine were received from 10 and 9 laboratories, respectively. Relative standard deviations for reproducibility for alpha-solanine and alpha-chaconine were similar, ranging from 8 to 13% in the applied concentration range of 12 to 260 mg/kg fresh weight.

  5. Selection of adsorption traps for in situ gas chromatographic analysis of polar regolith volatiles on board of the Luna-Resource lander

    Science.gov (United States)

    Aseev, Sergey; Gerasimov, Mikhail; Zaitsev, Maxim

    Investigation of volatile species in the polar regions of the Moon is an important task for better understanding of its evolution and for further exploration, in particular, to provide resources for future permanent stations. Gas chromatographic complex of Space Research Institute of the Russian Academy of Science is focused on measurements of volatile compounds composition, supposedly existing in the polar regions of the Moon in the area of Luna-Resource probe landing (2017). Also, this devise can be used on the Mars in the area of ExoMars landing mission (2018). One of the features of this gas analytical system is the use of adsorption traps, which can retain volatile compounds continuously coming into the gas chromatograph as a result of pyrolysis of the regolith sample and shortly release them for injection into chromatographic system for analysis. To improve sensitivity and analytical properties of the gas chromatograph, it’s necessary to provide concentrated injection of all the volatile components, which were released during pyrolysis of the regolith sample. It takes ~15 minutes to complete this pyrolysis operation. Such permanent gases as noble gases and N2, Ar, CO on the left hand have low dynamic viscosity, which cause their short retention time in adsorption traps, but on the right hand - these gases are released from the soil sample close to the end of the heating cycle. Summarizing these principles, we can say that 5 minutes of trapping for specified gases is efficient enough for their accumulation with consequent heating of adsorption trap up to 150°C to produce concentrated injection of all these compounds to the analytical columns of gas chromatography system. In the most of space missions (Viking, Phoenix, MSL, Rosetta), which use gas chromatography as the main method for in situ chemical analysis of volatiles, chromatography columns are usually mounted in parallel scheme. It is well known that water has a negative influence on analytical

  6. Dynamic Cluster Analysis: An Unbiased Method for Identifying A+2 Element Containing Compounds in Liquid Chromatographic High-Resolution TOF Mass Spectrometric Data

    DEFF Research Database (Denmark)

    Andersen, Aaron John Christian; Hansen, Per Juel; Jørgensen, Kevin

    2016-01-01

    Dynamic Cluster Analysis (DCA) is an automated, unbiased technique which can identify Cl, Br, S, and other A+2 element containing metabolites in liquid chromatographic high resolution mass spectrometric data. DCA is based on three features, primarily the previously unutilised A+1 to A+2 isotope...... cluster spacing which is a strong classifier in itself, but improved with the addition of the monoisotopic mass, and the well-known A:A+2 intensity ratio. Utilizing only the A+1 to A+2 isotope cluster spacing and the monoisotopic mass it was possible to filter a chromatogram for metabolites which contain...... Cl, Br, and S. Screening simulated isotope patterns of the Antibase Natural Products Database it was determined that the A+1 to A+2 isotope cluster spacing can be used to correctly classify 97.4% of molecular formulas containing these elements, only misclassifying a few metabolites which were either...

  7. Thin layer chromatography coupled with electrospray ionization mass spectrometry for direct analysis of raw samples.

    Science.gov (United States)

    Hu, Bin; Xin, Gui-zhong; So, Pui-Kin; Yao, Zhong-Ping

    2015-10-09

    Conventional mass spectrometric analysis of raw samples commonly requires sample pretreatment and chromatographic separation using high performance liquid chromatography or gas chromatography, which could be time-consuming and laborious. In this study, thin layer chromatography (TLC) coupled with electrospray ionization mass spectrometry (ESI-MS) was developed for direct analysis of raw samples. The sorbent material of the TLC plate was found to be able to retain the interfering compounds and allow interested analytes to be extracted, ionized and detected by ESI-MS with much reduced matrix interference. Our results showed that this method could be effectively applied in direct analysis of samples containing common interfering compounds, e.g., salts and detergents, and rapid detection and quantitation of target analytes in raw samples. Offline and online separation and detection of different components in mixture samples, e.g., plant extracts, using TLC-ESI-MS were also demonstrated. Overall, this study revealed that TLC-ESI-MS could be a simple, rapid and efficient method for analysis of raw samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Combined column-mobile phase mixture statistical design optimization of high-performance liquid chromatographic analysis of multicomponent systems.

    Science.gov (United States)

    Breitkreitz, Márcia C; Jardim, Isabel C S F; Bruns, Roy E

    2009-02-27

    A statistical approach for the simultaneous optimization of the mobile and stationary phases used in reversed-phase liquid chromatography is presented. Mixture designs using aqueous mixtures of acetonitrile (ACN), methanol (MeOH) and tetrahydrofuran (THF) organic modifiers were performed simultaneously with column type optimization, according to a split-plot design, to achieve the best separation of compounds in two sample sets: one containing 10 neutral compounds with similar retention factors and another containing 11 pesticides. Combined models were obtained by multiplying a linear model for column type, C8 or C18, by quadratic or special cubic mixture models. Instead of using an objective response function, combined models were built for elementary chromatographic criteria (retention factors, resolution and relative retention) of each solute or pair of solutes and, after their validation, the global separation was accomplished by means of Derringer's desirability functions. For neutral compounds a 37:12:8:43 (v/v/v/v) percentage mixture of ACN:MeOH:THF:H2O with the C18 column and for pesticides a 15:15:70 (v/v/v) ACN:THF:H2O mixture with the C8 column provide excellent resolution of all peaks.

  9. Application of high-performance liquid chromatographic methodology to the analysis of hemoglobins synthesized in erythroid progenitor cells.

    Science.gov (United States)

    Bhaumik, K; Huisman, T H

    1989-11-10

    High-performance liquid chromatography (HPLC) has been successfully used in the quantitation of the relatively minute amounts of hemoglobin types recovered from in vitro cultures of hemoglobin-synthesizing erythroid progenitor (BFU-E) cells. This reversed-phase HPLC method uses the Vydac C4 column and water-acetonitrile-trifluoroacetic acid as mobile phases; it has been applied to the study of fetal hemoglobin synthesis patterns in ten homozygous sickle cell anemia patients and a similar number of their heterozygous relatives along with a few normal control subjects. A significant increase in the total gamma chain level was observed in the BFU-E lysate samples corresponding to the whole blood lysates of all the patients and their heterozygous relatives, except in one patient with the beta S haplotype Mor. On the other hand, the relative level of the G gamma chains appeared to be decreased in the BFU-E lysate samples of all except the individuals carrying the Mor haplotype, where it is reversed. The method has considerable advantages over other chromatographic and electrophoretic procedures; it is extremely sensitive and allows quantitation of all different globin chains in one single chromatogram.

  10. A thin layer chromatographic comparison of raw and soluble starch hydrolysis patterns of some α-amylases from Bacillus sp. isolated in Serbia

    Directory of Open Access Journals (Sweden)

    Gligorijević Nikola

    2014-01-01

    Full Text Available Several natural isolates of Bacillus strains namely 5B, 12B, 16B, 18 and 24B were grown on two different temperatures in submerged fermentation for the raw-starch-digesting a-amylases production. All strains except Bacillus sp. 18 produced more α-amylase on 37ºC. The hydrolysis of raw corn starch followed same pattern. Efficient hydrolysis was obtained with α-amylases from Bacillus sp. 5B, 12B, 16B and 24B grown on 37ºC and Bacillus sp. 18 grown on 50ºC. Zymography after isoelectric focusing shown that α-amylases were produced in multiple forms, from 2 to 6, depending on the strain when they were growing at 37 ºC, while growing at 50ºC induced only 1 or 2 isoforms. TLC analysis of hydrolysis products of raw corn and soluble starch by α-amylases revealed production of various mixtures of oligosaccharides. In most cases G3 was the most dominant product from soluble starch while G2, G3 and G5 were the main products of raw starch hydrolysis. This indicates that obtained a-amylases can be used for starch liquefying or short-chain-oligosaccharide forming, depending on what type of starch (raw or soluble was used for the hydrolysis. [Projekat Ministarstva nauke Republike Srbije, br. 172048

  11. Improved Process Technique and Its Application of Chromatographic Analysis of Transformer Oil%变压器油色谱分析流程改进技术及应用

    Institute of Scientific and Technical Information of China (English)

    刘湘平

    2001-01-01

    采用填充多孔高聚物色谱柱单柱流程对SP3430气相色谱仪的变压器油色谱分析流程进行了改进。通过改进,仪器的精密度、分离度、保留时间、重复性以及最小检知浓度试验及应用等各项技术参数都符合GB/T 17623—1998国家标准。%Based on single column process of packed poromeric chromatographic column, the chromatographic analysis process of transformer oil with SP3430 gas chromatographic apparatus has been improved. After improvement, some testing and application parameters such as accuracy, separating degree, holding time, repeatability and minimum checkout concentration are up to the Chinese National Standard GB/T 17623-1998.

  12. Thin Layer Chromatography for the Analysis of Glycosaminoglycan Oligosaccharides

    OpenAIRE

    Zhang, Zhenqing; Xie, Jin; Zhang, Fuming; Linhardt, Robert J.

    2007-01-01

    Thin layer chromatography was used to analyze glycosaminoglycan oligosaccharides obtained through the use of polysaccharide lyases. This method allows for the rapid, semi-quantitative analysis of a wide variety of glycosaminoglycan oligosaccharides.

  13. Blocking layer modeling for temperature analysis of electron transfer ...

    African Journals Online (AJOL)

    Blocking layer modeling for temperature analysis of electron transfer rate in quantum dot sensitized solar cells. ... Journal of Fundamental and Applied Sciences ... of the quantum dots and free energy of system and finally the Marcus equation.

  14. Validation of a QuEChERS-based gas chromatographic method for analysis of pesticide residues in Cassia angustifolia (senna).

    Science.gov (United States)

    Tripathy, Vandana; Saha, Ajoy; Patel, Dilipkumar J; Basak, B B; Shah, Paresh G; Kumar, Jitendra

    2016-08-01

    A simple multi-residue method based on modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach was established for the determination of 17 organochlorine (OC), 15 organophosphorous (OP) and 7 synthetic pyrethroid (SP) pesticides in an economically important medicinal plant of India, Senna (Cassia angustifolia), by gas chromatography coupled to electron capture and flame thermionic detectors (GC/ECD/FTD) and confirmation of residues was done on gas chromatograph coupled with mass spectrometry (GC-MS). The developed method was validated by testing the following parameters: linearity, limit of detection (LOD), limit of quantification (LOQ), matrix effect, accuracy-precision and measurement uncertainty; the validation study clearly demonstrated the suitability of the method for its intended application. All pesticides showed good linearity in the range 0.01-1.0 μg mL(-1) for OCs and OPs and 0.05-2.5 μg mL(-1) for SPs with correlation coefficients higher than 0.98. The method gave good recoveries for most of the pesticides (70-120%) with intra-day and inter-day precision < 20% in most of the cases. The limits of detection varied from 0.003 to 0.03 mg kg(-1), and the LOQs were determined as 0.01-0.049 mg kg(-1). The expanded uncertainties were <30%, which was distinctively less than a maximum default value of ±50%. The proposed method was successfully applied to determine pesticide residues in 12 commercial market samples obtained from different locations in India.

  15. Potential for aging female Aedes aegypti (Diptera: Culicidae) by gas chromatographic analysis of cuticular hydrocarbons, including a field evaluation.

    Science.gov (United States)

    Desena, M L; Clark, J M; Edman, J D; Symington, S B; Scott, T W; Clark, G G; Peters, T M

    1999-11-01

    Gas chromatography with flame-ionization detection was used to measure the time-associated, quantitative changes in the cuticular hydrocarbons of female Aedes aegypti (L.). Cohorts of unstressed Ae. aegypti, Rockefeller strain, were reared and held at 3 constant temperatures (24, 28, and 30 degrees C). Five females from each cohort were taken at 33 degree-day (DD) intervals from 0 to 231 DD (using 17 degrees C as the threshold temperature). Quantitative changes over time of cuticular hydrocarbons associated with gas chromatographic peaks 1 and 5 were identified as having promise for age grading. The relative abundance of peak 1 (pentacosane) decreased linearly from 0 to 132 DD, whereas peak 5 (nonacosane) increased linearly over the same period. Suboptimal larval conditions (crowded and starved), which resulted in physiological stress (decreased size), had negligible effect on the relative abundance of pentacosane and nonacosane. Additionally, the rate of change in the relative abundance of pentacosane and nonacosane were the same for both a recently colonized Chachoengsao (Thailand) strain of Ae. aegypti compared with the long-colonized Rockefeller (Caribbean) strain over a 0-99 DD interval. Two linear regression models, one based on the relative abundance of pentacosane and the other on the logit transformation of these values, were developed for aging female Ae. aegypti. A blind study using laboratory-reared mosquitoes and a mark-release-recapture experiment using field mosquitoes validated these age-grading models and produced promising results for aging females up to 132 DD (19, 12, and 10 calendar days at 24, 28 and 30 degrees C, respectively). Therefore the regression models, based on the relative abundance of these 2 cuticular hydrocarbons, appeared to be a useful approach for age-grading Ae. aegypti up to at least 12 d of age regardless of environmental conditions (temperature and stress) and population history (origin and colonization time).

  16. Development of liquid chromatographic method for the analysis of dabigatran etexilate mesilate and its ten impurities supported by quality-by-design methodology.

    Science.gov (United States)

    Pantović, Jasmina; Malenović, Anđelija; Vemić, Ana; Kostić, Nađa; Medenica, Mirjana

    2015-01-01

    In this paper, the development of reversed-phase liquid chromatographic method for the analysis of dabigatran etexilate mesilate and its ten impurities supported by quality by design (QbD) approach is presented. The defined analytical target profile (ATP) was the efficient baseline separation and the accurate determination of the investigated analytes. The selected critical quality attributes (CQAs) were the separation criterions between the critical peak pairs because the mixture complexity imposed a gradient elution mode. The critical process parameters (CPPs) studied in this research were acetonitrile content at the beginning of gradient program, acetonitrile content at the end of gradient program and the gradient time. Plan of experiments was defined by Box-Behnken design. The experimental domains of the three selected factors x1--content of the acetonitrile at the start of linear gradient, x2--content of the acetonitrile at the end of linear gradient and x3--gradient time (tG) were [10%, 30%], [48%, 60%] and [8 min, 15 min], respectively. In order to define the design space (DS) as a zone where the desired quality criteria is met providing also the quality assurance, Monte Carlo simulations were performed. The uniform error distribution equal to the calculated standard error was added to the model coefficient estimates. Monte Carlo simulation included 5000 iterations in each of 3969 defined grid points and the region having the probability π ≥ 95% to achieve satisfactory values of all defined CQAs was computed. As a working point, following chromatographic conditions suited in the middle of the DS were chosen: 22% acetonitrile at the start of gradient program, 55.5% acetonitrile at the end of gradient program end and the gradient time of 11.5 min. The developed method was validated in order to prove its reliability.

  17. Layer-by-layer and intrinsic analysis of molecular and thermodynamic properties across soft interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sega, Marcello [Computational Physics Group, University of Vienna, Sensengasse 8/9, 1090 Vienna (Austria); Fábián, Balázs [Institut UTINAM (CNRS UMR 6213), Université de Franche-Comté, 16 route de Gray, F-25030 Besançon (France); Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest (Hungary); Jedlovszky, Pál [Laboratory of Interfaces and Nanosize Systems, Institute of Chemistry, Eötvös Loránd University, Pázmány P. Stny 1/A, H-1117 Budapest (Hungary); MTA-BME Research Group of Technical Analytical Chemistry, Szt. Gellért tér 4, H-1111 Budapest (Hungary); Department of Chemistry, EKF, Leányka u. 6, H-3300 Eger (Hungary)

    2015-09-21

    Interfaces are ubiquitous objects, whose thermodynamic behavior we only recently started to understand at the microscopic detail. Here, we borrow concepts from the techniques of surface identification and intrinsic analysis, to provide a complementary point of view on the density, stress, energy, and free energy distribution across liquid (“soft”) interfaces by analyzing the respective contributions coming from successive layers.

  18. Discovery of discriminatory quality control markers for Chinese herbal medicines and related processed products by combination of chromatographic analysis and chemometrics methods: Radix Scutellariae as a case study.

    Science.gov (United States)

    Wang, Fei; Wang, Bo; Wang, Long; Xiong, Zi-Yue; Gao, Wen; Li, Ping; Li, Hui-Jun

    2017-05-10

    The processing procedure of traditional Chinese herbal medicines (CHMs) plays an essential role in clinical applications. However, little progress has been made on the quality control of crude and processed products. The present work, taking Radix Scutellariae (RS), wine-processed RS and carbonized RS as a typical case, developed a comprehensive strategy integrating chromatographic analysis and chemometric methods for quality evaluation and discrimination of crude RS and its processed products. Chemical fingerprints were established by high-performance liquid chromatography coupled with photodiode array detector and quadrupole time-of-flight mass spectrometry, and similarity analyses were calculated based on eleven common characteristic peaks. Subsequently, four chemical markers were discovered by back propagation-artificial neural network (BP-ANN) modeling. The selected markers were quantified by the 'single standard to determine multi-components' (SSDMC) method, and then the quantitative data were subjected to principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA). Furthermore, support vector machine (SVM) was employed to predict the different processed products of RS. Finally, a hotmap visualization was conducted for clarifying the distribution of major flavonoids among different drugs. Collectively, the proposed strategy might be well-acceptable for quality control of CHMs and their related processed products from the processing mechanism-based perspective. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Rapid Analysis Procedures for Triglycerides and Fatty Acids as Pentyl and Phenethyl Esters for the Detection of Butter Adulteration Using Chromatographic Techniques

    Directory of Open Access Journals (Sweden)

    Daniele Naviglio

    2017-01-01

    Full Text Available This paper presents the development of three methods for quality control, fraud detection, and authentication of butter fat and other oils/fats using chromatographic techniques, with one method for triglycerides and two methods for fatty acids (FAs. The procedure for the analysis of triglycerides requires only dissolution of the sample in n-hexane and gas chromatography (GC analysis using a capillary column. The second method is based on the transesterification of triglycerides as pentyl esters in a single-step reaction using sodium pentanoate in pentanol. The reaction proceeds at room temperature and is similar to the potassium hydroxide-catalysed transesterification of triglycerides with methanol and even more similar to the sodium methoxide method and sodium butanoate method. The advantage of using pentyl esters includes reducing the volatility of short-chain FAs, and substantial recoveries were obtained compared with methyl ester analysis. The third method involves the transesterification of triglycerides in fat through reaction with 2-phenylethanol in a single step; 2-phenylethanol possesses a chromophore, and the phenethyl esters formed are analysed by high-performance liquid chromatography (HPLC with UV detection.

  20. Classification and characterisation of Spanish red wines according to their appellation of origin based on chromatographic profiles and chemometric data analysis.

    Science.gov (United States)

    Serrano-Lourido, Daniel; Saurina, Javier; Hernández-Cassou, Santiago; Checa, Antonio

    2012-12-01

    Chromatographic profiles of wines have been used as a fingerprint for the discrimination of Spanish wines based on oenological practices. In order to extract information of different families of phenolic compounds, profiles of different UV-vis absorption wavelengths (280, 310, 370 and 520nm) and fluorescence (ex=260nm; em=360nm) were analysed. A total of thirteen phenolic compounds which allowed the discrimination of wines of three different Spanish appellations (Penedes, Rioja and Ribera del Duero) were selected by means of principal component analysis (PCA). Afterwards, these compounds were used to build partial least squares discriminant analysis (PLS1-DA and PLS2-DA) models which allowed the discrimination of wines according to their appellation with classification rates for independent test sets higher than 96% and 93% for PLS1-DA and PLS2-DA models respectively. Finally, characteristic compounds of each appellation were tentatively identified by means of liquid chromatography-mass spectrometry (LC-MS) analysis. Thus, ten out of thirteen compounds (i.e., gallic acid for Penedes, trans-coumaroyltartaric and trans-caffeoyltartaric acids for Rioja and myricetin for Ribera del Duero wines) have been proposed.

  1. Infrared analysis of thin layers by attenuated total reflection spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rochat, N.; Chabli, A.; Bertin, F.; Vergnaud, C.; Mur, P.; Petitdidier, S.; Besson, P

    2003-09-15

    Interests in infrared spectroscopy (IRS) have been stimulated by the increasing need for non-destructive surface characterization providing structural and chemical informations about the new materials used in microelectronic devices. Standard infrared spectroscopy of thin layers is limited because of its lack of sensitivity. The use of optical configurations such as the attenuated total reflection (ATR) allows to characterize nanometric layers. This paper will present the results of a study conducted for a better understanding of the capabilities and limitations of this technique. A theoretical analysis based on a perturbation method is used to elucidate the results of ATR measurements performed on silicon oxide layers of different thickness on silicon substrates. This analysis shows that the absorbance ATR spectrum in p polarization is the image of the layer energy loss function, under specific conditions. The exact ATR spectrum simulation using a matrix formalism showed that the straightforward interpretation in terms of the layer dielectric function is limited to a very narrow layer thickness range. The fitting process of the ATR spectrum is evaluated for the interpretation of experimental spectra obtained for the growth of chemical silicon oxide layers.

  2. Buckling analysis of sandwich plate using layer wise theory

    Energy Technology Data Exchange (ETDEWEB)

    Ranjbaran, Arash; Khoshravan, Mohammad Reza [University of Tabriz, Tabriz (Iran, Islamic Republic of); Kharazi, Mahsa [Sahand University of Technology, Sahand (Iran, Islamic Republic of)

    2014-07-15

    Buckling analysis of sandwich plate was investigated using layer wise method. The formulation was based on the first-order shear deformation theory, and the Rayleigh-Ritz method was used for approximating and determining the displacement field. The results obtained from layer wise theory was compared with finite element results and showed good agreement. This study demonstrated that layer wise theory could describe buckling behavior of sandwich plates with high accuracy and represents a more realistic and acceptable description of behavior of the plates with much less computational cost.

  3. Stress Analysis in Polymeric Coating Layer Deposited on Rigid Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Soon Lee [Korea University of Technology and Education, School of Mechatronics Engineering, Chonan (Korea, Republic of)

    2015-08-15

    This paper presents an analysis of thermal stress induced along the interface between a polymeric coating layer and a steel substrate as a result of uniform temperature change. The epoxy layer is assumed to be a linear viscoelastic material and to be theromorheologically simple. The viscoelastic boundary element method is employed to investigate the behavior of interface stresses. The numerical results exhibit relaxation of interface stresses and large stress gradients, which are observed in the vicinity of the free surface. Since the exceedingly large stresses cannot be borne by the polymeric coating layer, local cracking or delamination can occur at the interface corner.

  4. Analysis of limited-entry well tests in layered reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, M.R.; Naismith, J.D.A.; Gunasekera, D.L.; Fitzpatrick, A.J.

    1994-12-31

    Vertical permeability, often a key parameter in reservoir engineering, can be calculated from the analysis of a limited entry pressure transient. Analytical solutions for limited entry welltests, where a fraction of the reservoir interval is perforated, have been available in the literature for some time. This paper considers the evaluation of limited entry welltests in heterogeneous layered formations. A number of field examples have been analyzed using both conventional analytical techniques and a new general purpose numerical welltest analysis application. The examples show that in layered formations vertical permeability can be significantly under estimated by conventional analytical analysis.

  5. 不同极性色谱柱在滇红香气成分分析中的对比研究%A Comparative Study of Different Polarity Chromatographic Column in Analysis of Aroma Components in Black Tea

    Institute of Scientific and Technical Information of China (English)

    乔阳; 杜丽平; 肖冬光

    2016-01-01

    The aroma components in black tea were extracted and analyzed by headspace solid phase micro extraction (HS-SPME) coupled with capillary gas chromatography-mass spectrometry (GC-MS). Two different polarity chromatographic columns were used for the separation of the aroma components in black tea. The result of semi-standard non-polar chromatographic column HP-5MS and standard polar chromatographic column CP-Wax were compared by analysis. The results indicated that the separation effect of two different polarity chromatographic column are satisfactory, and there are some differences between the analysis results. Therefore, in the analysis of different aroma components in black tea, we should select suitable chromatographic columns according to the various analytes.%采用顶空固相微萃取(HS-SPME)对滇红的香气成分进行富集,分别使用两种不同极性的色谱柱进行色谱分离,气质联用(GC-MS)检测分析,比较了非极性色谱柱 HP-5MS 和极性色谱柱 CP-Wax 对红茶香气成分分离效果的差异。结果表明,两种不同极性色谱柱对红茶香气成分的分离效果均表现良好,但分析结果存在一定的差异。因此在对红茶中不同的香气成分进行研究分析时,应根据分析目标的不同选择合适的色谱柱。

  6. Comparison of the phenolic composition of fruit juices by single step gradient HPLC analysis of multiple components versus multiple chromatographic runs optimised for individual families.

    Science.gov (United States)

    Bremner, P D; Blacklock, C J; Paganga, G; Mullen, W; Rice-Evans, C A; Crozier, A

    2000-06-01

    After minimal sample preparation, two different HPLC methodologies, one based on a single gradient reversed-phase HPLC step, the other on multiple HPLC runs each optimised for specific components, were used to investigate the composition of flavonoids and phenolic acids in apple and tomato juices. The principal components in apple juice were identified as chlorogenic acid, phloridzin, caffeic acid and p-coumaric acid. Tomato juice was found to contain chlorogenic acid, caffeic acid, p-coumaric acid, naringenin and rutin. The quantitative estimates of the levels of these compounds, obtained with the two HPLC procedures, were very similar, demonstrating that either method can be used to analyse accurately the phenolic components of apple and tomato juices. Chlorogenic acid in tomato juice was the only component not fully resolved in the single run study and the multiple run analysis prior to enzyme treatment. The single run system of analysis is recommended for the initial investigation of plant phenolics and the multiple run approach for analyses where chromatographic resolution requires improvement.

  7. Quality by Design approach in the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol and its impurities.

    Science.gov (United States)

    Jovanović, Marko; Rakić, Tijana; Tumpa, Anja; Jančić Stojanović, Biljana

    2015-06-10

    This study presents the development of hydrophilic interaction liquid chromatographic method for the analysis of iohexol, its endo-isomer and three impurities following Quality by Design (QbD) approach. The main objective of the method was to identify the conditions where adequate separation quality in minimal analysis duration could be achieved within a robust region that guarantees the stability of method performance. The relationship between critical process parameters (acetonitrile content in the mobile phase, pH of the water phase and ammonium acetate concentration in the water phase) and critical quality attributes is created applying design of experiments methodology. The defined mathematical models and Monte Carlo simulation are used to evaluate the risk of uncertainty in models prediction and incertitude in adjusting the process parameters and to identify the design space. The borders of the design space are experimentally verified and confirmed that the quality of the method is preserved in this region. Moreover, Plackett-Burman design is applied for experimental robustness testing and method is fully validated to verify the adequacy of selected optimal conditions: the analytical column ZIC HILIC (100 mm × 4.6 mm, 5 μm particle size); mobile phase consisted of acetonitrile-water phase (72 mM ammonium acetate, pH adjusted to 6.5 with glacial acetic acid) (86.7:13.3) v/v; column temperature 25 °C, mobile phase flow rate 1 mL min(-1), wavelength of detection 254 nm.

  8. Chromatographic fingerprint analysis and rutin and quercetin compositions in the leaf and whole-plant samples of di- and tetraploid Gynostemma pentaphyllum.

    Science.gov (United States)

    Xie, Zhuohong; Zhao, Yang; Chen, Pei; Jing, Pu; Yue, Jin; Yu, Liangli Lucy

    2011-04-13

    Gynostemma pentaphyllum (Thunb.) Makino, also known as jiaogulan, has been shown to have antioxidant, antiproliferative, and anti-inflammatory activities. Flavonoid is considered a major contributor for these beneficial effects. To obtain chemical patterns of flavonoids in G. pentaphyllum of different genotypes (di- versus tetraploids) and different parts (leaf versus whole plant) of plants, the extraction condition was optimized and a fingerprinting approach was established by means of high-performance liquid chromatography coupled with diode array detection and mass spectrometry (HPLC-DAD-MS). Eight flavonoids were identified, among which rutin and quercetin were quantified. The highest levels of rutin and quercetin were 23.03 and 12.10 mg/g, respectively, observed in the diploid leaf sample 2L3 and 2L2, while the lowest levels of rutin and quercetin were 1.92 and 0.25 mg/g in the tetraploid whole-plant sample 4W3. The chemical patterns were further analyzed by similarity calculation and principal component analysis (PCA). Seven common characteristic peaks were found in all of the tested samples. Flavonoid patterns of tetraploids were significantly different from those of diploids, whereas different parts of plants showed less difference. The flavonoid pattern of the diploid leaf sample was most similar to that of the reference botanical G. pentaphyllum. The combination of chromatographic fingerprint and quantification analysis could be used for quality assessment of G. pentaphyllum and its derived nutraceutical products.

  9. Analysis of Reaction between α-Lipoic Acid and 2-Chloro-1-methylquinolinium Tetrafluoroborate Used as a Precolumn Derivatization Technique in Chromatographic Determination of α-Lipoic Acid

    Directory of Open Access Journals (Sweden)

    Magdalena Godlewska

    2015-01-01

    Full Text Available The present study offers results of analysis concerning the course of reaction between reduced α-lipoic acid (LA and 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT. In water environments, the reaction between CMQT and hydrophilic thiols proceeds very rapidly and the resultant products are stable. For the described analysis, optimum reaction conditions, such as concentration of the reducing agent, environment pH, and concentration of the reagent were carefully selected. The spectrophotometric assay was carried out measuring absorbance at λ=348 nm (i.e., the spectral band of the obtained reaction product. Furthermore, the calibration curve of lipoic acid was registered. It was concluded that the Lambert-Beer law was observed within the range 1–10 μmol L−1. Later, the reaction between LA and CMQT was used as precolumn derivatization in a chromatographic determination of the lipoic acid in the range 2.5–50 μmol L−1. Practical applicability of the designed methods was evaluated by determining lipoic acid in Revitanerv pharmaceutical preparation which contains 300 mg LA in a single capsule. The error of the determination did not exceed 0.5% in relation to the declared value.

  10. Analysis of Reaction between α-Lipoic Acid and 2-Chloro-1-methylquinolinium Tetrafluoroborate Used as a Precolumn Derivatization Technique in Chromatographic Determination of α-Lipoic Acid.

    Science.gov (United States)

    Godlewska, Magdalena; Odachowska, Angelika; Turkowicz, Monika; Karpinska, Joanna

    2015-01-01

    The present study offers results of analysis concerning the course of reaction between reduced α-lipoic acid (LA) and 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT). In water environments, the reaction between CMQT and hydrophilic thiols proceeds very rapidly and the resultant products are stable. For the described analysis, optimum reaction conditions, such as concentration of the reducing agent, environment pH, and concentration of the reagent were carefully selected. The spectrophotometric assay was carried out measuring absorbance at λ = 348 nm (i.e., the spectral band of the obtained reaction product). Furthermore, the calibration curve of lipoic acid was registered. It was concluded that the Lambert-Beer law was observed within the range 1-10 μmol L(-1). Later, the reaction between LA and CMQT was used as precolumn derivatization in a chromatographic determination of the lipoic acid in the range 2.5-50 μmol L(-1). Practical applicability of the designed methods was evaluated by determining lipoic acid in Revitanerv pharmaceutical preparation which contains 300 mg LA in a single capsule. The error of the determination did not exceed 0.5% in relation to the declared value.

  11. Separation of Berberine Hydrochloride and Tetrahydropalmatine and Their Quantitative Analysis with Thin Layer Chromatography Involved with Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Jing Lu

    2015-01-01

    Full Text Available [BMIM]OH was used in mobile and stationary phase of thin layer chromatography (TLC to analyze berberine hydrochloride and tetrahydropalmatine for the first time. Supported imidazole ionic liquid with hydroxide ion on silica gel (SiO2·Im+·OH− was synthesized through simple procedure and characterized by Fourier transform infrared spectroscopy (FT-IR, elemental analysis, and scanning electron microscope (SEM. Moreover, on the plates prepared by SiO2·Im+·OH−, the contents of the above alkaloids in the Chinese patent medicine (CPM of “Stomacheasy” capsule were successfully determined by TLC scanner. The key conditions and chromatographic behaviors were also investigated in detail. According to similar ways, ionic liquids (ILs also can be used in other planar chromatographies in two modes. This study is expected to be helpful in expanding the application of IL and its bonded silica gel in TLC separation field.

  12. Chromatographic methods in the study of autism.

    Science.gov (United States)

    Żurawicz, Ewa; Kałużna-Czaplińska, Joanna; Rynkowski, Jacek

    2013-10-01

    Research into biomarkers of autism is a new means of medical intervention in this disease. Chromatographic techniques, especially coupled with mass spectrometry, are widely used in determination of biomarkers and assessment of effectiveness of autism therapy owing to their sensitivity and selectivity. Among the chromatographic techniques gas chromatography and liquid chromatography, especially high-performance liquid chromatography, have found application in clinical trials. The high-performance liquid chromatography technique allows an analysis of liquid samples with a wide range of molecules, small and large, providing an opportunity to perform advanced assays within a short time frame. Gas chromatography with the appropriate preparation of samples (gaseous and liquid) and a selection of analysis conditions enables the separation of thermally stable, volatile and non-volatile organic substances in short runtimes. The chromatographic techniques that are currently used in metabolic studies in autism are designed to identify abnormalities in three areas: the metabolism of neurotransmitters, nutritional and metabolic status and manifestations of oxidative stress. This review presents a necessary theoretical introduction and examples of applications of chromatographic studies of disorder markers in autism.

  13. Four Layered Approach to Non-Functional Requirements Analysis

    CERN Document Server

    Rao, A Ananda

    2012-01-01

    Identification of non-functional requirements is important for successful development and deployment of the software product. The acceptance of the software product by the customer depends on the non-functional requirements which are incorporated in the software. For this, we need to identify all the non-functional requirements required by all stakeholders. In the literature not many approaches are available for this purpose. Hence, we have proposed a four layered analysis approach for identification of non-functional requirements. The proposed layered approach has many advantages over non-layered approach. As part of this approach some rules are also proposed to be used in each layer. The approach is applied successfully on two case studies. The identified non-functional requirements are validated using a check list and in addition the completeness of the identified non-requirements is computed using a metric.

  14. ANALYSIS OF DIFFERENT BRANDS OF PARACETAMOL 500mg TABLETS USED IN MAIDUGURI, USING ULTRA VIOLET SPECTROPHOTOMETRIC AND HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC (HPLC METHODS

    Directory of Open Access Journals (Sweden)

    Sani Ali. Audu

    2012-08-01

    Full Text Available The study involves quantitative analysis of eight (8 different brands (samples of Paracetamol 500mg tablets used in Maiduguri, using Ultra Violet Spectrophotometric and High Performance Liquid Chromatographic methods, in which the samples were dissolved in 0.1M NaOH and distilled water and their various absorbances determined at wavelength of 257nm and the HPLC method. The results obtained were compared with that of the standard. Percentage content and content in mg for each sample was calculated using the absorbances and peak areas of the samples and that of the standard, to see if it is within the specified limit by official books (90%-110% according to USP. The percentage content of the analyzed samples using HPLC method ranges from 51.04-103.84%, while using UV method it ranges from 50.19-109.1%, indicating none of the samples contains less than 50% of the active principle. It was observed that five (5 samples Neimeth, Unclu P, Palmol, Emzol, Fidson, out of the eight (8 Neimeth, Unclu P, Palmol, Emzol, Shekdol, Fidson, Nemel, Arenol, analysed meet up the USP specified limit. After the calculation of the standard deviation and coefficient of variation of the two methods used, which are 123.5 and 27.7% respectively for UV method and 82.67 and 20.4% respectively for HPLC method, it was also observed that the HPLC method is more suitable for such kind of studies than the UV method,

  15. Concurrent supercritical fluid chromatographic analysis of terpene lactones and ginkgolic acids in Ginkgo biloba extracts and dietary supplements.

    Science.gov (United States)

    Wang, Mei; Carrell, Emily J; Chittiboyina, Amar G; Avula, Bharathi; Wang, Yan-Hong; Zhao, Jianping; Parcher, Jon F; Khan, Ikhlas A

    2016-07-01

    Supercritical fluid chromatography was used to resolve and determine ginkgolic acids (GAs) and terpene lactones concurrently in ginkgo plant materials and commercial dietary supplements. Analysis of GAs (C13:0, C15:0, C15:1, and C17:1) was carried out by ESI (-) mass detection. The ESI (-) spectra of GAs simply displayed only the [M-H](-) pseudo-molecular ions, and selected ion monitoring (SIM) for those ions was used for the quantification. Analysis of terpene lactones (ginkgolides A, B, C, J and bilobalide) was complicated by in-source collision-induced dissociation (IS-CID) in the ESI source. Thus, MS analysis could be influenced by the fragmentation pattern produced by the IS-CID. However, it was established that the fragmentation pattern, measured by ion survival yield (ISY), was independent of analyte concentration or matrix at a fixed cone voltage in the ESI source. Therefore, MS with SIM mode was applicable for the analysis of these analytes. The reported method provided consistent and sensitive analysis for the analytes of interest. The LOQs and LODs were determined to be below 100 and 40 ng/mL for GAs and 1 μg/mL and 400 ng/mL for terpene lactones, respectively. Intra- and inter-day precisions were found to be satisfactory with RSDs being below 5.2 %. Analyte recoveries ranged from 87 to 109 %. The developed method was successfully applied to the analysis of 11 ginkgo plant samples and 8 dietary supplements with an analysis time of less than 12 min.

  16. Fractionation of polyphenols in hawthorn into polymeric procyanidins, phenolic acids and flavonoids prior to high-performance liquid chromatographic analysis.

    Science.gov (United States)

    Svedström, Ulla; Vuorela, Heikki; Kostiainen, Risto; Laakso, Into; Hiltunen, Raimo

    2006-04-21

    Polymeric procyanidins, phenolic carboxylic acids and flavonoids of hawthorn (Crataegus laevigata) were fractionated prior to HPLC analysis using column chromatography and solid-phase extraction (SPE). The flavonoid fraction also contained (-)-epicatechin. The three groups of phenolics, each with clearly different UV spectra, were examined by means of high-performance liquid chromatography-diode array detection (HPLC-DAD) analysis. The average repeatability of the method (RSD) was in the range of 8-13% for chlorogenic acid, (-)-epicatechin and hyperoside. The polymeric procyanidins of hawthorn flowers consisted mainly of (-)-epicatechin subunits, and their mean degree of polymerization (DP) was 22.2. The HPLC methods developed can be used for the qualitative and quantitative analysis of different phenolic compounds in hawthorn plant material and their extracts.

  17. Optimisation and characterisation of silica-based reversed-phase liquid chromatographic systems for the analysis of basic pharmaceuticals

    NARCIS (Netherlands)

    Vervoort, RJM; Debets, AJJ; Claessens, HA; Cramers, CA; de Jong, GJ

    2000-01-01

    Reversed-phase liquid chromatography using silica-based columns is successfully applied in many separations. However, also some drawbacks exist, i.e. the analysis of basic compounds is often hampered by ionic interaction of the basic analytes with residual silanols present on the silica surface, whi

  18. The short and long of it: shorter chromatographic analysis suffice for sample classification during UHPLC-MS-based metabolic fingerprinting

    CSIR Research Space (South Africa)

    Madala, NE

    2013-03-01

    Full Text Available status or origin. UHPLC-MS data from chemically-treated Arabidopsis thaliana plants were used and chromatograms with different gradient lengths were compared. MarkerLynxTM technology was employed for data mining, followed by principal component analysis...

  19. 变压器在线色谱监测装置的应用分析%Application Analysis of Transformer On-line Chromatograph Monitor

    Institute of Scientific and Technical Information of China (English)

    劳永闯; 何燕

    2014-01-01

    简述了在线色谱监测装置的类型及其相关检测原理,将中分3000型在线色谱监测装置与实验室色谱仪进行比较,并通过应用实例分析,指出在线色谱监测技术在变压器状态检修和运行监测中的重要性,最后对在线色谱监测装置的选用提出了一些建议。%This paper briefly describes types and relevant testing principles of the on-line chromatograph monitors. By comparing Zhongfen-3000 on-line chromatograph monitoring device with chromatograph in labo-ratory and analyzing application examples , this paper illustrates the importance of on-line chromatograph mon-itoring technology in condition-based maintenance and operation monitoring of transformer. Finally the paper puts forward suggestions for selecting and use of on-line chromatograph monitoring device.

  20. Application of chemometric analysis based on physicochemical and chromatographic data for the differentiation origin of plant protection products containing chlorpyrifos.

    Science.gov (United States)

    Miszczyk, Marek; Płonka, Marlena; Bober, Katarzyna; Dołowy, Małgorzata; Pyka, Alina; Pszczolińska, Klaudia

    2015-01-01

    The aim of this study was to investigate the similarities and dissimilarities between the pesticide samples in form of emulsifiable concentrates (EC) formulation containing chlorpyrifos as active ingredient coming from different sources (i.e., shops and wholesales) and also belonging to various series. The results obtained by the Headspace Gas Chromatography-Mass Spectrometry method and also some selected physicochemical properties of examined pesticides including pH, density, stability, active ingredient and water content in pesticides tested were compared using two chemometric methods. Applicability of simple cluster analysis and also principal component analysis of obtained data in differentiation of examined plant protection products coming from different sources was confirmed. It would be advantageous in the routine control of originality and also in the detection of counterfeit pesticides, respectively, among commercially available pesticides containing chlorpyrifos as an active ingredient.

  1. Quantitative analysis combined with chromatographic fingerprint and antioxidant activities for the comprehensive evaluation of Compound Danshen Tablets.

    Science.gov (United States)

    Chen, Jiao; Gao, Jiayue; Sun, Guoxiang

    2017-03-01

    The composition of traditional Chinese medicine is extremely complex, so it is difficult to ensure quality consistency. We took Compound Danshen Tablets as the object of the study, by using high-performance liquid chromatography to establish multiwavelength fusion fingerprints. Characteristic fingerprints of 30 batches of samples were generated at four wavelengths and evaluated by systematic quantified fingerprint method. An on-line antioxidant determination method was used for the determination of the antioxidant components in Compound Danshen Tablets. The fingerprint analysis of the marker compounds can reflect the content of the marker compounds, which were determined by using the external standard method. This study elucidated that multiwavelength fusion fingerprint profiles and multiple markers compound analysis in conjunction with the assay of antioxidant activity offered a reliable and efficient approach to quantitatively evaluate the quality consistency of the traditional Chinese medicine and herbal preparations.

  2. Comparison of column phase configurations for comprehensive two dimensional gas chromatographic analysis of crude oil and bitumen

    Energy Technology Data Exchange (ETDEWEB)

    Tran, T.C.; Harynuk, J.; Marriott, P. [RMIT University, Melbourne (Australia). Dept. of Applied Chemistry; Logan, G.A.; Grosjean, E. [Geoscience Australia, Canberra (Australia); Ryan, D. [Charles Sturt University, Wagga Wagga (Australia). School of Science and Technology

    2006-09-15

    An inverted phase (polar to non-polar) column set has been compared with a non-polar to polar column set for the GC x GC separation of petroleum hydrocarbons. This column configuration is shown to provide greatly enhanced resolution for less polar compounds and makes greater use of the two dimensional separation space. It improves resolution of a greater number of components within one analysis and offers new possibilities for crude oil fingerprinting. (Author)

  3. Quality assessment of raw and processed Arctium lappa L. through multicomponent quantification, chromatographic fingerprint, and related chemometric analysis.

    Science.gov (United States)

    Qin, Kunming; Wang, Bin; Li, Weidong; Cai, Hao; Chen, Danni; Liu, Xiao; Yin, Fangzhou; Cai, Baochang

    2015-05-01

    In traditional Chinese medicine, raw and processed herbs are used to treat different diseases. Suitable quality assessment methods are crucial for the discrimination between raw and processed herbs. The dried fruit of Arctium lappa L. and their processed products are widely used in traditional Chinese medicine, yet their therapeutic effects are different. In this study, a novel strategy using high-performance liquid chromatography and diode array detection coupled with multivariate statistical analysis to rapidly explore raw and processed Arctium lappa L. was proposed and validated. Four main components in a total of 30 batches of raw and processed Fructus Arctii samples were analyzed, and ten characteristic peaks were identified in the fingerprint common pattern. Furthermore, similarity evaluation, principal component analysis, and hierachical cluster analysis were applied to demonstrate the distinction. The results suggested that the relative amounts of the chemical components of raw and processed Fructus Arctii samples are different. This new method has been successfully applied to detect the raw and processed Fructus Arctii in marketed herbal medicinal products.

  4. Pareto distance for multi-layer network analysis

    DEFF Research Database (Denmark)

    Magnani, Matteo; Rossi, Luca

    2013-01-01

    services, e.g., Facebook, Twitter, LinkedIn and Foursquare. As a result, the analysis of on-line social networks requires a wider scope and, more technically speaking, models for the representation of this fragmented scenario. The recent introduction of more realistic layered models has however determined...... on the nature of the connections required by the Pareto distance may in theory result in a large number of potential shortest paths between pairs of nodes. However, an experimental computation of distances on multi-layer networks of increasing size shows an interesting and non-trivial stable behavior....

  5. Analysis of anti-neoplastic drug in bacterial ghost matrix, w/o/w double nanoemulsion and w/o nanoemulsion by a validated 'green' liquid chromatographic method.

    Science.gov (United States)

    Youssof, Abdullah M E; Salem-Bekhit, Mounir M; Shakeel, Faiyaz; Alanazi, Fars K; Haq, Nazrul

    2016-07-01

    The objective of the present investigation was to develop and validate a 'green' reversed phase high-performance liquid chromatography (RP-HPLC) method for rapid analysis of a cytotoxic drug 5-fluorouracil (5-FU) in bulk drug, marketed injection, water-in-oil (w/o) nanoemulsion, double water-in-oil-in-water (w/o/w) nanoemulsion and bacterial ghost (BG) matrix. The chromatography study was carried out at room temperature (25±1°C) using an HPLC system with the help of ultraviolet (UV)-visible detector. The chromatographic performance was achieved with a Nucleodur 150mm×4.6mm RP C8 column filled with 5µm filler as a static phase. The mobile phase consisted of ethyl acetate: methanol (7:3% v/v) which was delivered at a flow rate of 1.0mLmin(-1) and the drug was detected in UV mode at 254nm. The developed method was validated in terms of linearity (r(2)=0.998), accuracy (98.19-102.09%), precision (% RSD=0.58-1.17), robustness (% RSD=0.12-0.53) and sensitivity with satisfactory results. The efficiency of the method was demonstrated by the assay of the drug in marketed injection, w/o nanoemulsion, w/o/w nanoemulsion and BG with satisfactory results. The successful resolution of the drug along with its degradation products clearly established the stability-indicating nature of the proposed method. Overall, these results suggested that the proposed analytical method could be effectively applied to the routine analysis of 5-FU in bulk drug, various pharmaceutical dosage forms and BG.

  6. 气相色谱仪在气体组分分析中的应用%The application of gas chromatograph in gas composition analysis

    Institute of Scientific and Technical Information of China (English)

    李军

    2013-01-01

    色谱仪具有相当高的灵敏度和选择性,目前已被广泛地应用在过程工业中。本文简述了气象色谱仪的工作原理及基本结构,介绍了气相色谱常用的TCD、FPD、FID的工作原理。主要针对某项目中低温甲醇洗的具体工况,介绍了气相色谱仪的应用。%As the chromatograph has the excellent properties of sensitivity and selectivity,it has been widely used in process industry.This paper introduces the principle and configuration of gas chromatograph,and the principle of TCD,FPD,FID which have been widely used.Additionaly,this paper presents the application of gas chromatograph in rectisol technology.

  7. Direct thermal desorption of semivolatile organic compounds from diffusion denuders and gas chromatographic analysis for trace concentration measurement.

    Energy Technology Data Exchange (ETDEWEB)

    Tobias, D. E.; Perlinger, J. A.; Morrow, P. S.; Doskey, P. V.; Perram, D.L.; Environmental Science Division; Michigan Technological Univ.

    2007-01-01

    A novel method for collection and analysis of vapor-phase semivolatile organic compounds (SOCs) in ambient air is presented. The method utilizes thermal desorption of SOCs trapped in diffusion denuders coupled with cryogenic preconcentration on Tenax-TA and analysis by high resolution gas chromatography (GC)-electron-capture detection (ECD). The sampling and analysis methods employ custom-fabricated multicapillary diffusion denuders, a hot gas spike (HGS) apparatus to load known quantities of thermally stable standards into diffusion denuders prior to sample collection, a custom-fabricated oven to thermally desorb SOCs from the diffusion denuder, and a programmable temperature vaporization (PTV) inlet containing a liner packed with Tenax-TA for effective preconcentration of the analytes and water management. High flow rates into the PTV inlet of 750 mL min-1during thermal desorption are ca. a factor of ten greater than typically used. To improve resolution and retention time stability, the thermal desorption and PTV inlet programming procedure includes three steps to prevent water from entering the analytic column while effectively transferring the analytes into the GC system. The instrumentation and procedures provide virtually complete and consistent transfer of analytes collected from ambient air into the GC evidenced by recovery of seven replicates of four internal standards of 90.7 {+-} 4.0-120 {+-} 23% (mean {+-} 95% confidence interval, CI). Retention time based compound identification is facilitated by low retention time variability with an average 95% CI of 0.024 min for sixteen replicates of eight standards. Procedure details and performance metrics as well as ambient sampling results are presented.

  8. Direct thermal desorption of semivolatile organic compounds from diffusion denuders and gas chromatographic analysis for trace concentration measurement.

    Science.gov (United States)

    Tobias, David E; Perlinger, Judith A; Morrow, Patrick S; Doskey, Paul V; Perram, David L

    2007-01-26

    A novel method for collection and analysis of vapor-phase semivolatile organic compounds (SOCs) in ambient air is presented. The method utilizes thermal desorption of SOCs trapped in diffusion denuders coupled with cryogenic preconcentration on Tenax-TA and analysis by high resolution gas chromatography (GC)-electron-capture detection (ECD). The sampling and analysis methods employ custom-fabricated multicapillary diffusion denuders, a hot gas spike (HGS) apparatus to load known quantities of thermally stable standards into diffusion denuders prior to sample collection, a custom-fabricated oven to thermally desorb SOCs from the diffusion denuder, and a programmable temperature vaporization (PTV) inlet containing a liner packed with Tenax-TA for effective preconcentration of the analytes and water management. High flow rates into the PTV inlet of 750mLmin(-1)during thermal desorption are ca. a factor of ten greater than typically used. To improve resolution and retention time stability, the thermal desorption and PTV inlet programming procedure includes three steps to prevent water from entering the analytic column while effectively transferring the analytes into the GC system. The instrumentation and procedures provide virtually complete and consistent transfer of analytes collected from ambient air into the GC evidenced by recovery of seven replicates of four internal standards of 90.7+/-4.0-120+/-23% (mean+/-95% confidence interval, CI). Retention time based compound identification is facilitated by low retention time variability with an average 95% CI of 0.024min for sixteen replicates of eight standards. Procedure details and performance metrics as well as ambient sampling results are presented.

  9. High-performance liquid chromatographic analysis of dextromethorphan, guaifenesin and benzoate in a cough syrup for stability testing.

    Science.gov (United States)

    Galli, V; Barbas, C

    2004-09-10

    A method has been developed for the analysis of a cough syrup containing dextromethorphan, guaifenesin, benzoic acid, saccharin and other components. Forced degradation was also studied to demonstrate that the method could be employed during a stability study of the syrup. Final conditions were phosphate buffer (25 mM, pH 2.8) with triethylamine (TEA)-acetonitrile (75:25, v/v). In such conditions, all the actives, excipients and degradation products were baseline resolved in less than 14 min, and different wavelengths were used for the different analytes and related compounds.

  10. Authenticity control of essential oils containing citronellal and citral by chiral and stable-isotope gas-chromatographic analysis.

    Science.gov (United States)

    Nhu-Trang, Tran-Thi; Casabianca, Hervé; Grenier-Loustalot, Marie-Florence

    2006-12-01

    Enantioselective capillary GC on a Supelco beta-DEX 225 column (heptakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-beta-cyclodextrin SPB 20poly--20% diphenyl, 80% dimethylsiloxane) and isotope-ratio mass spectrometry, coupled online with capillary GC on an HP5 column have been used for origin-specific analysis and authenticity control of essential oils, for example lemon (Citrus limon), lemongrass (Cymbopogon citratus and Cymbopogon flexuosus), citronella (Cymbopogon nardus L.--Ceylon type and Cymbopogon winterianus--Java type), Litsea cubeba, Lippia citriodora, lemon myrtle (Backhousia citriodora), lemon gum (Eucalyptus citriodora), and, especially, precious lemon balm oil (Melissa officinalis L.). Isotope data (delta13C(PDB) and delta2H(V-SMOW)) for citral (neral + geranial) and citronellal from on-line GC-C/Py-IRMS and chiral data for citronellal in these essential oils are reported. The possibility of using these data to determine the origin of these essential oils and to detect adulteration is discussed. Principal-components analysis (PCA) of specific compounds in two essential oils of lemongrass and Litsea cubeba was performed as a practical statistical method for distinguishing between these two types of oil.

  11. Seasonal Variation, Microscopic and Chromatographic Analysis of Leaves in Malus hupehensis: A Protocol for Its Quality Control

    Institute of Scientific and Technical Information of China (English)

    SHEN Tao; XIANG Lan; REN Dong-mei; WANG Shu-qi; YANG Ming-ren; LOU Hong-xiang

    2013-01-01

    Objective To establish a quality control protocol based on microscopic,TLC,and HPLC methods,and to verify the optimal harvesting time for the leaves of Malus hupehensis (LMH).Methods The LMH were pulverized into powder for microscopic identification or TLC and HPLC analysis after ultrasonic extraction with methanol.Seasonal variations of the phlorizin content and average leaf weight were determined by HPLC analysis and weighing up the leaves collected from May to October.Results Microscopic and macromorphologic characteristics have been described for the leaf identification.A qualitative TLC assay and a quantitative HPLC method have been established for the quality control of LMH.Phlorizin was selected as a reference marker,which resolved at Rf0.53 in TLC assay and at 14.0 min in HPLC assay.The content of phlorizin decreased gradually from 17.0% in leaves collected in May to 7.5% in October.The average leaf weight reached the level of 0.6 g in August and maintained until its falling.Conclusion These methods are simple,selective,accurate,and reliable for the quality control of LMH.The period from late August to early September is suggested as the optimal harvesting time of the LMH.

  12. Determination of DNA adducts by combining acid-catalyzed hydrolysis and chromatographic analysis of the carcinogen-modified nucleobases.

    Science.gov (United States)

    Leung, Elvis M K; Deng, Kailin; Wong, Tin-Yan; Chan, Wan

    2016-01-01

    The commonly used method of analyzing carcinogen-induced DNA adducts involves the hydrolysis of carcinogen-modified DNA samples by using a mixture of enzymes, followed by (32)P-postlabeling or liquid chromatography (LC)-based analyses of carcinogen-modified mononucleotides/nucleosides. In the present study, we report the development and application of a new approach to DNA adduct analysis by combining the H(+)/heat-catalyzed release of carcinogen-modified nucleobases and the use of LC-based methods to analyze DNA adducts. Results showed that heating the carcinogen-modified DNA samples at 70 °C for an extended period of 4 to 6 h in the presence of 0.05% HCl can efficiently induce DNA depurination, releasing the intact carcinogen-modified nucleobases for LC analyses. After optimizing the hydrolysis conditions, DNA samples with C8- and N (2) -modified 2'-deoxyguanosine, as well as N (6) -modified 2'-deoxyadenosine, were synthesized by reacting DNA with 1-nitropyrene, acetaldehyde, and aristolochic acids, respectively. These samples were then hydrolyzed, and the released nucleobase adducts were analyzed using LC-based analytical methods. Analysis results demonstrated a dose-dependent release of target DNA adducts from carcinogen-modified DNA samples, indicating that the developed H(+)/heat-catalyzed hydrolysis method was quantitative. Comparative studies with enzymatic digestion method on carcinogen-modified DNA samples revealed that the two hydrolysis methods did not yield systematically different results.

  13. 气相色谱分析技术在焦化工业中的应用进展%Application and Development of Gas Chromatographic Technique in the Proximate Analysis in Coking Industry

    Institute of Scientific and Technical Information of China (English)

    闫俊杰

    2011-01-01

    综述了近年来气相色谱技术在焦化工业分析方面的应用,包括:回收系统气相色谱分析、焦油加工系统气相色谱分析、环保领域气相色谱分析等.对比分析了各方法的要点和特点,并结合宣钢焦化厂的应用情况及作者的工作实践进行了评述.%Application of Gas Chromatographic Technique in coking proximate analysis in recent years was introduced. It involved gas chromatographic analysis of the recovery system, tar processing system, some environmental protection aspects, etc. The main points and features of various methods were discussed and compared, and some comments were put forward. It was suggested that the gas chromatographic technique should be applied more extensively in the future to meet the needs of the fast development of the proximate analysis in the coking industry.

  14. A high performance liquid chromatographic method of analysis of 4'-O-tetrahydropyranyladriamycin and their metabolites in biological samples.

    Science.gov (United States)

    Matsushita, Y; Iguchi, H; Kiyosaki, T; Tone, H; Ishikura, T; Takeuchi, T; Umezawa, H

    1983-07-01

    A method for measuring 4'-O-tetrahydropyranyladriamycin (THP) and its metabolites in biological samples are described. By reversed-phase high performance liquid chromatography using fluorescence detection, THP and its metabolites were all separated on a single chromatogram within 18 minutes. A linear calibration curve was obtained up to 2,000 ng/ml of THP in plasma. The recovery of THP in the analysis was more than 95% above 5 ng/ml and 87.1% even at 1.25 ng/ml. Thus the lower limit was 1.25 ng/ml in biological samples. Blood levels and urinary excretion in mice and dogs were satisfactory measured by this analytical method.

  15. Development of a chromatographic low pressure flow injection system using amperometric detection: Application to the analysis of niacin in coffee.

    Science.gov (United States)

    Santos, João Rodrigo; Rangel, António O S S

    2015-11-15

    In this work, an analytical flow system able to perform low pressure chromatography with amperometric detection is presented. As case study, the determination of niacin (vitamin B3) in coffee brewed samples was selected. The manifold comprised a 1.0 cm length monolithic column coated with didecyldimethylammonium bromide, a laboratory-made boron doped diamond electrode, and featured in-line ionic strength adjustment of the mobile phase. The figures of merit concerning the selected case study namely, detection limit, 7.90 × 10(-7) M, determination rate, ca. 10 samplesh(-1), mobile phase and ISA solution consumption, ca. 2.6 mL per analysis, and CV, below 5% for retention time and peak height, showed the competitiveness of this analytical strategy comparing to the described HPLC methods for niacin determination. The strategy displays a simple configuration, low cost, fast and easy assembling, foreseeing its use to general purpose applications.

  16. Comprehensive ultra-performance liquid chromatographic separation and mass spectrometric analysis of eicosanoid metabolites in human samples.

    Science.gov (United States)

    Wang, Yan; Armando, Aaron M; Quehenberger, Oswald; Yan, Chao; Dennis, Edward A

    2014-09-12

    Over the past decade, the number of known eicosanoids has expanded immensely and we have now developed an ultra-performance liquid chromatography-electrospray ionization triple quadrupole mass spectrometric (UPLC-QTRAP/MS/MS) method to monitor and quantify numerous eicosanoids. The UPLC-QTRAP/MS/MS approach utilizes scheduled multiple reaction monitoring (MRM) to optimize sensitivity, number of metabolites that can be analyzed and the time requirement of the analysis. A total of 184 eicosanoids including 26 deuterated internal standards can be separated and monitored in a single 5min UPLC run. To demonstrate a practical application, human plasma samples were analyzed following solid-phase extraction (SPE) and the recovery rate and matrix effects were determined for the 26 deuterated internal standards added to the plasma. The method was validated and shown to be sensitive with the limit of quantitation at pg levels for most compounds, accurate with recovery rates of 70-120%, and precise with a CVeicosanoids.

  17. Isolation and identification of phytoestrogens and flavonoids in an Ayurvedic proprietary medicine using chromatographic and Mass Spectroscopic analysis

    Institute of Scientific and Technical Information of China (English)

    Sulaiman CT; Arun A; Anandan EM; Sandhya CR; Indira Balachandran

    2015-01-01

    Objective: To develop analytical methods for the isolation and structural identification of poly phenols including phytoestrogens in Mensokot tablet, a herbal proprietary medicine. Methods:Isolation consisted of an ultrasound-assisted extraction, followed by acid hydrolysis and a final liquid-liquid extraction step in diethyl ether. Identification and structural characterisation was done by liquid chromatography coupled with Q-TOF-ESI-MS/MS analysis. Results:Phytoestrogens such as Coumestrol, Genistein and Glycitein have been identified in Mensokot tablet along with several other flavonoids. Conclusion: In the present research, a rapid HPLC-MS/MS method has been developed for the identification of phytoestrogens and other flavonoids from an Ayurvedic proprietary medicine. Phytoestrogens are considered to play an important role in the prevention of cancers, heart disease, menopausal symptoms and osteoporosis.

  18. Analysis of differential infrared thermography for boundary layer transition detection

    Science.gov (United States)

    Gardner, A. D.; Eder, C.; Wolf, C. C.; Raffel, M.

    2017-09-01

    This paper presents an analysis of the differential infrared thermography (DIT) technique, a contactless method of measuring the unsteady movement of the boundary layer transition position on an unprepared surface. DIT has been shown to measure boundary layer transition positions which correlate well with those from other measurement methods. In this paper unsteady aerodynamics from a 2D URANS solution are used and the resulting wall temperatures computed. It is shown that the peak of the temperature difference signal correlates well with the boundary layer transition position, but that the start and end of boundary layer transition cannot be extracted. A small systematic time-lag cannot be reduced by using different surface materials, but the signal strength can be improved by reducing the heat capacity and heat transfer of the surface layer, for example by using a thin plastic coating. Reducing the image time separation used to produce the difference images reduces the time-lag and also the signal level, thus the optimum is when the signal to noise ratio is at the minimum which can be evaluated.

  19. Analysis of black carbon molecular markers by two chromatographic methods (GC-FID and HPLC-DAD)

    Science.gov (United States)

    Schneider, Maximilian P. W.; Smittenberg, Rienk H.; Dittmar, Thorsten; Schmidt, Michael W. I.

    2010-05-01

    The analysis of benzenepolycarboxylic acids (BPCA) as a quantitative measure for black carbon (BC) in soil and sediment samples is a well-established method [1, 2]. Briefly, the oxidation of polycondensated BC molecules forms seven molecular markers, which can be assigned to BC, and which subsequently can be quantified by GC-FID (gas chromatography with flame ionization detector). Recently this method has been refined for BC quantification in seawater samples measuring BPCA on HPLC-DAD (High performance liquid chromatography with diode array detector) [3]. However, a systematic comparison of BC as determined by both analytical techniques would be essential to the calculation of global BC budgets, but is lacking. Here we present data for the systematic comparison of the two BPCA methods, both for quantity and quality. We prepared chars under well-defined laboratory conditions. Chestnut hardwood chips and rice straw were pyrolysed at temperatures between 200 and 1000°C under constant N2 stream. The BC contents of the chars have been analysed using the BPCA extraction method followed by either GC-FID or HPLC-DAD quantification [4]. It appears that the GC-FID method yields systematically lower concentrations of BPCA in the chars compared to the HPLC-DAD method. Possible reasons for the observed difference are i) higher losses of sample material during preparation for GC-FID; ii) different quality of the linear regression used for quantification; iii) incomplete derivatisation of B5CA and B6CA, which is needed for GC-FID analysis. In a next step, we will test different derivatisation procedures (methylation with dimethyl sulfate or diazomethane, and silylation) for their influence on the GC-FID results. The aim of this study is to test if black carbon can be quantified in soil, sediment and water samples using one single method - a crucial step when attempting a global BC budget. References: [1] Brodowski, S., Rodionov, A., Haumeier L., Glaser, B., Amelung, W. (2005

  20. Simultaneous high performance liquid chromatographic analysis of vitamins B1, B2 and B6 in royal jelly

    Directory of Open Access Journals (Sweden)

    Presoto Ana Elisa F

    2004-01-01

    Full Text Available Royal jelly is used as a food supplement, popularly known as rich in B vitamins. The present work has two objectives: firstly, to apply simultaneous quantitative determination by High Performance Liquid Chromatography of thiamin (vitamin B1, riboflavin (vitamin B2 and pyridoxine (vitamin B6 and secondly to compare the obtained data with the Dietary Reference Intake (DRI values. The values obtained showed no thiamin, a range from 20 to 171 ng g-1 of riboflavin and from 408 to 2 188 ng g-1 of pyridoxine in royal jelly. According to the Food and Nutrition Board (2000, the DRI of these vitamins varies from 0.2-1.4 mg for thiamin; 0.3-1.6 mg for riboflavin and 0.1-2.0 mg for pyridoxine, depending on age and sex. According to these recommendations, royal jelly is not a good source of vitamins B1, B2 or B6 as these vitamins appear only on order of ng g-1. The proposed method can be used in routine analysis for royal jelly, having the advantage of being simple, fast and reliable.

  1. Antioxidant Activity and Gas Chromatographic-Mass Spectrometric Analysis of Extracts of the Marine Algae, Caulerpa peltata and Padina Gymnospora.

    Science.gov (United States)

    Murugan, Kavitha; Iyer, Vidhya V

    2014-01-01

    The results of our previous investigations on extracts of selected marine algae showed that Caulerpa peltata and Padina gymnospora had more promising antiproliferative and antioxidant activities than Gelidiella acerosa and Sargassum wightii. Based on these results, the more active chloroform extract of C. peltata and ethyl acetate extract of P. gymnospora were further analyzed for their constituents by using gas chromatography in tandem with mass spectrometry. The GC-MS analysis (GC % peak area given in parentheses) showed that fucosterol (12.45%) and L-(+)-ascorbic acid 2, 6-dihexadecanoate (8.13%) were the major compounds present in P. gymnospora ethyl acetate extract. On the other hand, C. peltata chloroform extract had 1-heptacosanol (10.52%), hexacosanol acetate (9.28%), tetradecyl ester of chloroacetic acid (7.22%), Z,Z-6, 28-heptatriactontadien-2-one (6.77%) and 10, 13-dimethyl-methyl ester of tetradecanoic acid (5.34%) as major compounds. Also described in the report are the beta-carotene bleaching inhibitory and total reducing activities of the chloroform and ethyl acetate extracts of C. peltata and P. gymnospora, respectively, relative to the other three extracts (aqueous, methanol, chloroform or ethyl acetate) of the two algae.

  2. A SURVEY OF LIQUID CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS OF MERCAPTURIC ACID BIOMARKERS IN OCCUPATIONAL AND ENVIRONMENTAL EXPOSURE MONITORING

    Science.gov (United States)

    Mathias, Patricia I.; B’Hymer, Clayton

    2015-01-01

    High-performance liquid chromatography/mass spectrometry (HPLC/MS) is sensitive and specific for targeted quantitative analysis and is readily utilized for small molecules from biological matricies. This brief review describes recent selected HPLC/MS methods for the determination of urinary mercapturic acids (mercapturates) which are useful as biomarkers in characterizing human exposure to electrophilic industrial chemicals in occupational and environmental studies. Electrophilic compounds owing to their reactivity are used in chemical and industrial processes. They are present in industrial emissions, are combustion products of fossil fuels, and are components in tobacco smoke. Their presence in both the industrial and general environment are of concern for human and environmental health. Urinary mercapturates which are the products of metabolic detoxification of reactive chemicals provide a non-invasive tool to investigate human exposure to electrophilic toxicants. Selected recent mercapturate quantification methods are summarized and specific cases are presented. The biological formation of mercapturates is introduced and their use as biomarkers of metabolic processing of electrophilic compounds is discussed. Also, the use of liquid chromatography/tandem mass spectrometry in simultaneous determinations of the mercapturates of multiple parent compounds in a single determination is considered, as well as future trends and limitations in this area of research. PMID:24746702

  3. Simultaneous analysis of multiple lipid oxidation products in vivo by liquid chromatographic-mass spectrometry (LC-MS).

    Science.gov (United States)

    Yin, Huiyong; Davis, Todd; Porter, Ned A

    2010-01-01

    Free radical-induced oxidation of polyunsaturated fatty acid (PUFAs) has been linked to a number of human diseases including atherosclerosis and neurodegenerative disorders. Oxidation of PUFAs generates hydroperoxides and cyclic peroxides that are reduced to lipid alcohol, such as hydroxyeicosatetraenoic acid (HETEs), and isoprostanes (IsoPs) respectively. The IsoPs are isomers of prostaglandins that are generated from autoxidation of arachidonic acid (C20:4). Quantification of F(2)-IsoPs has been regarded as the "gold standard" to assess oxidative stress status in various human diseases. We herein report the protocol of analyzing HETEs and F(2)-IsoPs using a triple quadrupole mass spectrometer coupled to reverse phase liquid chromatography. The selected reaction monitoring (SRM) mode selects the parent ion of interest in the first Quad (m/z 319 for HETE and m/z 353 for F(2)-IsoPs) and fragments it in the second while an ion characteristic of the analyte of interest is monitored in the third Quad. This highly selective technique permits the simultaneous analysis of multiple oxidation products such as the HETEs and F(2)-IsoPs. This LC-MS technique can be applied to study the free radical oxidation mechanism in vitro and assess the oxidative stress status in biological tissues and fluids.

  4. Unintended compositional changes in transgenic rice seeds ( Oryza sativa L.) studied by spectral and chromatographic analysis coupled with chemometrics methods.

    Science.gov (United States)

    Jiao, Zhe; Si, Xiao-xi; Li, Gong-ke; Zhang, Zhuo-min; Xu, Xin-ping

    2010-02-10

    Unintended compositional changes in transgenic rice seeds were studied by near-infrared reflectance, GC-MS, HPLC, and ICP-AES coupled with chemometrics strategies. Three kinds of transgenic rice with resistance to fungal diseases or insect pests were comparatively studied with the nontransgenic counterparts in terms of key nutrients such as protein, amino acids, fatty acids, vitamins, elements, and antinutrient phytic acid recommended by the Organization for Economic Co-operation and Development (OECD). The compositional profiles were discriminated by chemometrics methods, and the discriminatory compounds were protein, three amino acids, two fatty acids, two vitamins, and several elements. Significance of differences for these compounds was proved by analysis of variance, and the variation extent ranged from 20 to 74% for amino acids, from 19 to 38% for fatty acids, from 25 to 57% for vitamins, from 20 to 50% for elements, and 25% for protein, whereas phytic acid content did not change significantly. The unintended compositional alterations as well as unintended change of physical characteristic in transgenic rice compared with nontransgenic rice might be related to the genetic transformation, the effect of which needs to be elucidated by additional studies.

  5. Combined mass spectrometric and chromatographic methods for in-depth analysis of phenolic secondary metabolites in barley leaves.

    Science.gov (United States)

    Piasecka, Anna; Sawikowska, Aneta; Krajewski, Paweł; Kachlicki, Piotr

    2015-03-01

    Structural analysis via HPLC-ESI-MSn, UPLC-HESI-MS/MS and NMR reported 152 phenolic secondary metabolites in spring barley seedlings (Hordeum vulgare L.). Flavonoids with various patterns of glycosylation and acylation, as well as hydroxycinnamic acid glycosides, esters and amides, were identified in methanolic extracts from leaves of nine varieties of barley originating from different regions of the world. Hordatines derivatives, flavones acylated directly on the aglycone, and hydroxyferulic acid derivatives deserve special attention. Preparative chromatography enabled characterization of a number of compounds at trace levels with the 6-C-[6″-O-glycosyl]-glycosides and the 6-C-[2″,6″-di-O-glycosides]-glucoside structure of flavones. Derivatives of flavonols, quercetin and isorhamnetin were observed only in Syrian varieties. The ultra performance liquid chromatography profiles of UV-absorbing secondary metabolites were used for chemotaxonomic comparison between nine varieties of barley from different climatic conditions. The hierarchical clustering of bred lines from the Fertile Crescent and European and American varieties indicates a great diversity of chemical phenotypes within barley species.

  6. Antioxidant activity and gas chromatographic-mass spectrometric analysis of extracts of the marine algae, caulerpa peltata and padina gymnospora

    Directory of Open Access Journals (Sweden)

    Kavitha Murugan

    2014-01-01

    Full Text Available The results of our previous investigations on extracts of selected marine algae showed that Caulerpa peltata and Padina gymnospora had more promising antiproliferative and antioxidant activities than Gelidiella acerosa and Sargassum wightii. Based on these results, the more active chloroform extract of C. peltata and ethyl acetate extract of P. gymnospora were further analyzed for their constituents by using gas chromatography in tandem with mass spectrometry. The GC-MS analysis (GC % peak area given in parentheses showed that fucosterol (12.45% and L-(+-ascorbic acid 2,6-dihexadecanoate (8.13% were the major compounds present in P. gymnospora ethyl acetate extract. On the other hand, C. peltata chloroform extract had 1-heptacosanol (10.52%, hexacosanol acetate (9.28%, tetradecyl ester of chloroacetic acid (7.22%, Z,Z-6,28-heptatriactontadien-2-one (6.77% and 10,13-dimethyl-methyl ester of tetradecanoic acid (5.34% as major compounds. Also described in the report are the beta-carotene bleaching inhibitory and total reducing activities of the chloroform and ethyl acetate extracts of C. peltata and P. gymnospora, respectively, relative to the other three extracts (aqueous, methanol, chloroform or ethyl acetate of the two algae.

  7. Development of an Ion Chromatography Method for Analysis of Organic Anions (Fumarate, Oxalate, Succinate, and Tartrate) in Single Chromatographic Conditions.

    Science.gov (United States)

    Kaviraj, Yarbagi; Srikanth, B; Moses Babu, J; Venkateswara Rao, B; Paul Douglas, S

    2015-01-01

    A single organic counterion analysis method was developed by using an ion chromatography separation technique and conductivity detector. This allows the rapid characterization of an API to support clinical studies and to fulfil the regulatory requirements for the quantitation of fumarate, oxalate, succinate, and tartrate counterions in active pharmaceutical ingredients (quetiapine fumarate, escitalopram oxalate, sumatriptan succinate, and tolterodine tartrate). The method was developed by using the Metrohm Metrosep A Supp 1 (250 × 4.0 mm, 5.0 µm particle size) column with a mobile phase containing an isocratic mixture of solution A: 7.5 mM sodium carbonate and 2.0 mM sodium bicarbonate in Milli-Q water and solution B: acetonitrile. The flow rate was set at 1.0 mL/min and the run time was 25 minutes. The developed method was validated as per ICH guidelines, and the method parameters were chosen to ensure the spontaneous quantitation of all four anions. The method was validated for all four anions to demonstrate the applicability of this method to common anions present in various APIs.

  8. Numerical Analysis of Piles in Layered Soils: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Ravi Kumar Reddy C

    2015-04-01

    Full Text Available In this paper, numerical analysis of a pile-soil interaction problem is presented considering the parameters influencing the axial load-deformation behavior of the pile embedded in a layered soil medium. The analysis is demonstrated with parametric solutions of a pile with underlain model soil strata under the axial force. An attempt is made to ascertain the extent of influence of elastic properties of the pile, geometry of the pile, end conditions of the pile and the elastic properties of the underlain soil strata on the response of the piles under axial loads lying in a model soil layers in terms of the settlement of the pile and the internal deformation of the pile. The study revealed that the increase in modulus of elasticity of pile improves the settlement resistance of the pile, increase in the ratio of cross sectional dimensions causes decrease in the top deformations of the pile, the settlement of the pile reduced to a great extent when the cross section of the pile adopted is non circular instead of circular and increase in the elastic modulii of top and bottom layers of soil has decreased the settlement of the pile to a great extent, but elastic modulus of soil layers other than top and bottom has got negligible influence on the settlement of the pile.

  9. Multiresolution analysis of density fluctuation in supersonic mixing layer

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Due to the difficulties in measuring supersonic density field, the multiresolution analysis of supersonic mixing layer based on experimental images is still a formidable challenge. By utilizing the recently developed nanoparticle based planar laser scattering method, the density field of a supersonic mixing layer was measured at high spatiotemporal resolution. According to the dynamic behavior of coherent structures, the multiresolution characteristics of density fluctuation signals and density field images were studied based on Taylor’s hypothesis of space-time conversion and wavelet analysis. The wavelet coefficients reflect the characteristics of density fluctuation signals at different scales, and the detailed coefficients reflect the differences of approximation at adjacent levels. The density fluctuation signals of supersonic mixing layer differ from the periodic sine signal and exhibit similarity to the fractal Koch signal. The similarity at different scales reveals the fractal characteristic of mixing layer flowfield. The two-dimensional wavelet decomposition and reconstruction of density field images extract the approximate and detailed signals at different scales, which effectively resolve the characteristic structures of the flowfield at different scales.

  10. Extraction chromatographic methods in the sample preparation sequence for thermal ionization mass spectrometric analysis of plutonium isotopes.

    Science.gov (United States)

    Grate, Jay W; O'Hara, Matthew J; Farawila, Anne F; Douglas, Matthew; Haney, Morgan M; Petersen, Steven L; Maiti, Tapas C; Aardahl, Christopher L

    2011-12-01

    A sample preparation sequence for actinide isotopic analysis by thermal ionization mass spectrometry (TIMS) is described that includes column-based extraction chromatography as the first separation step, followed by anion-exchange column separations. The sequence is designed to include a wet ashing step after the extraction chromatography to prevent any leached extractant or oxalic acid eluent reagents from interfering with subsequent separations, source preparation, or TIMS ionization. TEVA resin and DGA resin materials, containing extractants that consist only of C, N, O, and H atoms, were investigated for isolation of plutonium. Radiotracer level studies confirmed expected high yields from column-based separation procedures. Femtogram-level studies were carried out with TIMS detection, using multiple monoisotopic spikes applied sequentially throughout the separation sequence. Pu recoveries were 87% and 86% for TEVA and DGA resin separations, respectively. The Pu recoveries from 400 μL anion-exchange column separation sequences were 89% and 93% for trial sequences incorporating TEVA and DGA resin. Thus, a prior extraction chromatography step in the sequence did not interfere with the subsequent anion-exchange separation when a simple wet ash step was carried out in between these column separations. The average measurement efficiency for Pu, encompassing the chemical separation recoveries and the TIMS ionization efficiency, was 2.73% ± 0.77% (2σ) for the DGA resin trials and 2.67% ± 0.54% for the TEVA resin trials, compared to 3.41% and 2.37% (average 2.89%) for two control trials. These compare with an average measurement efficiency of 2.78% ± 1.70%, n = 33 from process benchmark analyses using Pu spikes processed through a sequence of oxalate precipitation, wet ash, iron hydroxide precipitation, and anion-exchange column separations. We conclude that extraction chromatography can be a viable separation procedure as part of a multistep sequence for TIMS

  11. Chromatographic finger print analysis and lysosomal membrane stabilisation activity of active fraction of Alstonia scholaris leaf extract in arthritic rats

    Directory of Open Access Journals (Sweden)

    Swapnil Goyal

    2014-01-01

    Full Text Available Object: The present study was aimed to assess the anti-arthritic activity of chloroform fraction of Alstonia scholaris leaf extract against Freund′s complete adjuvant (FCA-induced arthritis in rats. Materials and Methods: The anti-inflammatory activity of various fractions of ethanolic extract of Alstonia scholaris at concentration of 100 mg/kg was studied using the carrageenan-induced inflammatory models. The chloroform fraction shows significant anti-inflammatory activity. The chloroform fraction was further studied for anti-arthritic activity and HPTLC fingerprint analysis. For anti-arthritic activity, the active chloroform fraction was administered at the concentrations of 50 and 100 mg/kg body weight. The effect of chloroform fraction on liver ALP, ACP and LDH levels of lysosomal enzymes of FCA arthritic animals were studied. Indomethacin and prednisolone (10 mg/kg was used as standard. HPTLC studies were carried out using CAMAG HPTLC system equipped with linomat IV applicator, TLC scanner; Reprostar 3 and WIN CATS-4 software were used. Results: The chloroform fraction at 100 mg/kg, showed maximum inhibition (34.16% of inflammation induced by carrageenan. In FCA-induced arthritis, the chloroform fraction showed a highly significant reduction in paw volume (50 mg/kg-72.71%; 100 mg/kg-74.35%. The levels of lysosomal enzymes were significantly decreased in the chloroform fraction-treated groups. Conclusion: The possible mechanism of action of the chloroform fraction of Alstonia scholaris leaf extract may be through its stabilising action on lysosomal membranes. Future studies will provide new insights into the anti-arthritic activity of Alstonia scholaris and isolation of compound from it may eventually lead to development of a new class of anti-arthritic agent.

  12. Non-chromatographic screening procedure for arsenic speciation analysis in fish-based baby foods by using electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Garcia, Ignacio; Briceno, Marisol [Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, E-30071 Murcia (Spain); Hernandez-Cordoba, Manuel, E-mail: hcordoba@um.es [Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, E-30071 Murcia (Spain)

    2011-08-05

    Highlights: {yields} Arsenic in fish-based food samples can be determined without the need of a dissolution stage. {yields} Speciation of the main forms of arsenic in fish-based baby foods does not require chromatography. {yields} The behavior of arsenic compounds in ETAAS strongly depends on the chemical modifier used. - Abstract: A procedure for the speciation analysis of arsenic in fish-based baby foods is presented. Inorganic arsenic, methylarsonic acid (MA), dimethylarsinic acid (DMA) and arsenobetaine (AB) were determined by electrothermal atomic absorption spectrometry (ETAAS) using suspensions prepared in a 0.01 mol L{sup -1} tetramethylammonium hydroxide (TMAH) solution. Speciation is based on the use of three different chemically modified ETAAS atomizers to obtain the analytical signals. Using a palladium salt as the chemical modifier, the signal corresponding to the total arsenic concentration is obtained. When palladium is replaced by Ce(IV), the signal is solely due to inorganic arsenic (III and V) + MA. If no signal is obtained in this latter case, it is possible to distinguish between DMA and AB using a zirconium coated atomizer. The signal obtained in this way is due solely to DMA, and the concentration of AB can be obtained by the difference with the total arsenic content. Determinations by ETAAS require the use of the standard additions method. The limits of detection for the determination of AB, DMA and inorganic arsenic (+MA) are 15, 25 and 50 ng g{sup -1} expressed as arsenic, respectively. These detection limits are good enough for the procedure to be appropriate for the rapid determination of these compounds, avoiding extraction processes and/or chromatographic separations. Data for commercial samples, as well as for four standard reference materials, are given.

  13. Evaluation of gas chromatographic isotope fractionation and process contamination by carbon in compound-specific radiocarbon analysis.

    Science.gov (United States)

    Zencak, Zdenek; Reddy, Christopher M; Teuten, Emma L; Xu, Li; McNichol, Ann P; Gustafsson, Orjan

    2007-03-01

    The relevance of both modern and fossil carbon contamination as well as isotope fractionation during preparative gas chromatography for compound-specific radiocarbon analysis (CSRA) was evaluated. Two independent laboratories investigated the influence of modern carbon contamination in the sample cleanup procedure and preparative capillary gas chromatography (pcGC) of a radiocarbon-dead 3,3',4,4',5,5'-hexachlorobiphenyl (PCB 169) reference. The isolated samples were analyzed for their 14C/12C ratio by accelerator mass spectrometry. Sample Delta14C values of -996 +/- 20 and -985 +/- 20 per thousand agreed with a Delta14C of -995 +/- 20 per thousand for the unprocessed PCB 169, suggesting that no significant contamination by nonfossil carbon was introduced during the sample preparation process at either laboratory. A reference compound containing a modern 14C/12C ratio (vanillin) was employed to evaluate process contamination from fossil C. No negative bias due to fossil C was observed (sample Delta14C value of 165 +/- 20 per thousand agreed with Delta14C of 155 +/- 12 per thousand for the unprocessed vanillin). The extent of isotopic fractionation that can be induced during pcGC was evaluated by partially collecting the vanillin model compound of modern 14C/12C abundance. A significant change in the delta13C and delta14C values was observed when only parts of the eluting peak were collected (delta13C values ranged from -15.75 to -49.91 per thousand and delta14C values from -82.4 to +4.71 per thousand). Delta14C values, which are normalized to a delta13C of -25 per thousand, did not deviate significantly (-58.9 to -5.8 per thousand, considering the uncertainty of approximately +/-20 per thousand). This means that normalization of radiocarbon results to a delta13C of -25 per thousand, normally performed to remove effects of environmental isotope fractionation on 14C-based age determinations, also cor-rects sufficiently for putative isotopic fractionation that may

  14. Analysis of Abnormal Chromatographic Data of Transformer HV Bushing%变压器高压套管色谱异常分析

    Institute of Scientific and Technical Information of China (English)

    刘胜军; 何镔; 刘红春

    2012-01-01

    The reason of abnormal chromatographic data of 220kV capacitive oil-paper HV bushing is analyzed. The preventive measures are presented.%分析了一起220kV电容式油纸高压套管色谱异常的故障原因,并提出了预防措施。

  15. Pareto distance for multi-layer network analysis

    DEFF Research Database (Denmark)

    Magnani, Matteo; Rossi, Luca

    2013-01-01

    Social Network Analysis has been historically applied to single networks, e.g., interaction networks between co-workers. However, the advent of on-line social network sites has emphasized the stratified structure of our social experience. Individuals usually spread their identities over multiple...... services, e.g., Facebook, Twitter, LinkedIn and Foursquare. As a result, the analysis of on-line social networks requires a wider scope and, more technically speaking, models for the representation of this fragmented scenario. The recent introduction of more realistic layered models has however determined...... new research problems related to the extension of traditional single-layer network measures. In this paper we take a step forward over existing approaches by defining a new concept of geodesic distance that includes heterogeneous networks and connections with very limited assumptions regarding...

  16. Note on the chromatographic analyses of marine polyunsaturated fatty acids

    Science.gov (United States)

    Schultz, D.M.; Quinn, J.G.

    1977-01-01

    Gas-liquid chromatography was used to study the effects of saponification/methylation and thin-layer chromatographic isolation on the analyses of polyunsaturated fatty acids. Using selected procedures, the qualitative and quantitative distribution of these acids in marine organisms can be determined with a high degree of accuracy. ?? 1977 Springer-Verlag.

  17. 油色谱分析在变压器状态监测中的应用研究%Application of Oil Chromatographic Analysis to Transformer Fault Diagnosis

    Institute of Scientific and Technical Information of China (English)

    李晨

    2012-01-01

      电力变压器发生潜在性故障时,绝缘油会分解产生烃类气体,采用油色谱法分析这些烃类气体,可诊断出电压器中存在的潜伏性故障信息,保证设备可靠运行;首先分析了油色谱分析的原理,然后设计了变压器油色谱在线监测系统,最后测试表明利用油色谱技术对变压器故障进行分析诊断的有效性和正确性。%  Hydrocarbon gas will be generated by the decomposition of the Insulating oil when there is a potential failure in pow⁃er transformers,the potential failure is diagnosed by using Oil Chromatographic Analysis to Hydrocarbon gas,firstly,this paper analyses the principle of Oil chromatographic,and it designs the on-line transformer oil chromatography monitoring system,in the end, the experiment shows the Validity and correctness of using the use of oil chromatographic techniques to Diagnosis the Transformer Fault.

  18. Multiplex real-time quantitative PCR, microscopy and rapid diagnostic immuno-chromatographic tests for the detection of Plasmodium spp: performance, limit of detection analysis and quality assurance

    Directory of Open Access Journals (Sweden)

    Ralevski Filip

    2009-12-01

    Full Text Available Abstract Background Accurate laboratory diagnosis of malaria species in returning travelers is paramount in the treatment of this potentially fatal infectious disease. Materials and methods A total of 466 blood specimens from returning travelers to Africa, Asia, and South/Central America with suspected malaria infection were collected between 2007 and 2009 at the reference public health laboratory. These specimens were assessed by reference microscopy, multipex real-time quantitative polymerase chain reaction (QPCR, and two rapid diagnostic immuno-chromatographic tests (ICT in a blinded manner. Key clinical laboratory parameters such as limit of detection (LOD analysis on clinical specimens by parasite stage, inter-reader variability of ICTs, staffing implications, quality assurance and cost analysis were evaluated. Results QPCR is the most analytically sensitive method (sensitivity 99.41%, followed by CARESTART (sensitivity 88.24%, and BINAXNOW (sensitivity 86.47% for the diagnosis of malaria in returning travelers when compared to reference microscopy. However, microscopy was unable to specifically identify Plasmodia spp. in 18 out of 170 positive samples by QPCR. Moreover, the 17 samples that were negative by microscopy and positive by QPCR were also positive by ICTs. Quality assurance was achieved for QPCR by exchanging a blinded proficiency panel with another reference laboratory. The Kappa value of inter-reader variability among three readers for BINAXNOW and CARESTART was calculated to be 0.872 and 0.898 respectively. Serial dilution studies demonstrated that the QPCR cycle threshold correlates linearly with parasitemia (R2 = 0.9746 in a clinically relevant dynamic range and retains a LOD of 11 rDNA copies/μl for P. falciparum, which was several log lower than reference microscopy and ICTs. LOD for QPCR is affected not only by parasitemia but the parasite stage distribution of each clinical specimen. QPCR was approximately 6-fold more

  19. Quantifying process tradeoffs in the operation of chromatographic sequences.

    Science.gov (United States)

    Ngiam, Sheau-Huey; Bracewell, Daniel G; Zhou, Yuhong; Titchener-Hooker, Nigel J

    2003-01-01

    A method for the rapid representation of key process tradeoffs that need to be made during the analysis of chromatographic sequences has been proposed. It involves the construction of fractionation and maximum purification factor versus yield diagrams, which can be completed easily on the basis of chromatographic data. The output of the framework developed reflects the degree of tradeoff between levels of yield and purity and provides a fast and precise prediction of the sample fraction collection strategy needed to meet a desired process specification. The usefulness of this approach for the purposes of product purification and contaminant removal in a single chromatographic step has been successfully demonstrated in an earlier paper and it is now extended by application to a chromatographic sequence: the separation of a hypothetical three-component protein system by hydrophobic interaction chromatography (HIC) followed by size exclusion chromatography (SEC). The HIC operation has a strong impact upon the subsequent SEC step. The studies show how the analysis of performance in such a chromatographic sequence can be carried out easily and in a straightforward fashion using the fractionation diagram approach. The methodology proposed serves as a useful tool for identifying the process tradeoffs that must be made during operation of a sequence of chromatographic steps and indicates the impact on further processing of the cut-point decisions that are made.

  20. GC-2000Ⅱ型气相色谱仪的故障分析与处理%Fault Analysis and Treatment of GC2000II Gas Chromatograph

    Institute of Scientific and Technical Information of China (English)

    李建军

    2015-01-01

    GC-2000Ⅱ gas chromatograph, which is high performance chromatographic instrument controlled by microcomputer, has widely used in coking industry, and can accurately detect the benzene content in rich and poor oil and coke oven gas. This paper introduces the various faults in the use process of GC-2000Ⅱ gas chromatograph, and puts forward some corresponding treatment measures.%GC-2000Ⅱ气相色谱仪是微机控制的高性能色谱仪器, 配置氢焰FID检测器的GC-2000Ⅱ气相色谱仪在焦化行业大量使用,它可以准确地检测出贫富油含苯和煤气含苯. 介绍了GC-2000Ⅱ气相色谱仪在使用过程中出现的各种故障现象,提出了相应的处理措施.

  1. A Comparative Study of Chromatographic Behavior and Lipophilicity of Selected Imidazoline Derivatives.

    Science.gov (United States)

    Filipic, Slavica; Antic, Aleksandra; Vujovic, Milena; Nikolic, Katarina; Agbaba, Danica

    2016-08-01

    Chromatographic behavior and lipophilicity of 20 selected imidazoline derivatives were examined by thin-layer chromatography using CN, RP-2, RP-8 and RP-18 as the stationary phases and a mixture of methanol, water and ammonia as the mobile phase. In all examined chromatographic systems, linear relationships were established between retention parameters and the volume fraction of methanol in the mobile phase (r > 0.985, 0.978, 0.981, 0.988 for the CN, RP-2, RP-8 and RP-18, respectively). The highest correlation between the obtained [Formula: see text] values was observed for RP-2 and RP-8 stationary phases. The experimental lipophilicity indices ([Formula: see text], m and C0) obtained from the retention data were used in correlation study with the calculated logP values. Experimentally determined [Formula: see text] values for all investigated chromatographic systems exhibited the highest correlation with the calculated ClogP values (r: 0.880, 0.872, 0.897 and 0.889 for the CN, RP-2, RP-8 and RP-18 stationary phases, respectively). In addition, principal component analysis enables new information about similarity and differences between tested compounds as well as experimental lipophilicity indices and calculated logP values. Performed QSRR analysis showed that the frequency of C-C at topological distance 1 and CATS2D Lipophilic-Lipophilic at lag 01 were important descriptors with influence on the [Formula: see text] values in all the examined chromatographic systems, while the differences in the retention behavior of compounds on the examined stationary phases can be distinguished based on their specific geometrical, electronic and constitutional properties.

  2. Analysis of wafer heating in 14nm DUV layers

    Science.gov (United States)

    Subramany, Lokesh; Chung, Woong Jae; Samudrala, Pavan; Gao, Haiyong; Aung, Nyan; Gomez, Juan Manuel; Minghetti, Blandine; Lee, Shawn

    2016-03-01

    To further shrink the contact and trench dimensions, Negative Tone Development (NTD) has become the de facto process at these layers. The NTD process uses a positive tone resist and an organic solvent-based negative tone developer which leads to improved image contrast, larger process window and smaller Mask Error Enhancement Factor (MEEF)[1]. The NTD masks have high transmission values leading to lens heating and as observed here wafer heating as well. Both lens and wafer heating will contribute to overlay error, however the effects of lens heating can be mitigated by applying lens heating corrections while no such corrections exist for wafer heating yet. Although the magnitude of overlay error due to wafer heating is low relative to lens heating; ever tightening overlay requirements imply that the distortions due to wafer heating will quickly become a significant part of the overlay budget. In this work the effects, analysis and observations of wafer heating on contact and metal layers of the 14nm node are presented. On product wafers it manifests as a difference in the scan up and scan down signatures between layers. An experiment to further understand wafer heating is performed with a test reticle that is used to monitor scanner performance.

  3. Multivariate analyses of NP-TLC chromatographic retention data for grouping of structurally-related plant secondary metabolites.

    Science.gov (United States)

    Shawky, Eman

    2016-09-01

    The chromatographic behavior of 28 plant secondary metabolites belonging to four chemically similar classes (alkaloids, flavonoids, flavone glycosides and sesquiterpenes) was studied by normal-phase thin-layer chromatography (NP-TLC) under 5 different chromatographic systems commonly used in plant drug analysis with the aim to explore whether the retention properties of these metabolites can determine the chemical group they belong to. The use of RM values as the retention parameter is implemented as a relatively new approach in plant analysis. Principal component analysis (PCA), hierarchical clustering heat maps and discriminant analysis (DA), were used for statistical evaluation of the chromatographic data and extraction of similarities between chemically related compounds. The twenty eight metabolites were classified into four groups by principal component analysis. The heat map of hierarchical clustering revealed that all metabolites were clustered into four groups, except for caffeine, while linear discriminant analysis showed that 96.4% of metabolites are predicted correctly as the groupings identified by chemical class in original and cross-validated data. The main advantage of the approach described in current paper is its simplicity which can assist with preliminary identification of metabolites in complex plant extracts. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Continuous melting and ion chromatographic analyses of ice cores.

    Science.gov (United States)

    Huber, T M; Schwikowski, M; Gäggele, H W

    2001-06-22

    A new method for determining concentrations of organic and inorganic ions in ice cores by continuous melting and contemporaneous ion chromatographic analyses was developed. A subcore is melted on a melting device and the meltwater produced is collected in two parallel sample loops and then analyzed simultaneously by two ion chromatographs, one for anions and one for cations. For most of the analyzed species, lower or equal blank values were achieved with the continuous melting and analysis technique compared to the conventional analysis. Comparison of the continuous melting and ion chromatographic analysis with the conventional analysis of a real ice core segment showed good agreement in concentration profiles and total amounts of ionic species. Thus, the newly developed method is well suited for ice core analysis and has the advantages of lower ice consumption, less time-consuming sample preparation and lower risk of contamination.

  5. Application of Gas Chromatograph-Mass Spectrometry in Gun-Powder Analysis%气相色谱-质谱联用法在火药剖析中的应用

    Institute of Scientific and Technical Information of China (English)

    李俊平; 崔桂萍; 李彩青; 任洁; 梁瑞红

    2012-01-01

    采用固液萃取的方法对火药样品进行处理,用气相色谱-质谱联用法对某未知火药进行成分剖析,以选择离子质谱法进行定量.目标化合物浓度在20~50 mg/L范围内与色谱峰面积呈良好的线性关系,相关系数在0.9940~0.9996之间.方法加标回收率为96.9%~ 104.3%,测定结果的相对标准偏差为2.4%~4.9%(n=5).气相色谱-质谱联用法可用于火药剖析研究.%The gun-powder sample was treated by solid-liquid extraction method, the components in unknown gun-powder were anatomized by gas chromatograph-mass spectrometry. Selective ion quantitativis method was used for quantitative analysis. The concentration of target compound was linear with chromatographic peak area in the range of 20-50 mg/L, the correlation coefficient was 0.9940-0.9996. The recovery rate was 96.9%-104.3% and relative standard deviation of analysis results was 0.4%-4.9%(n=5). Gas chromatograph-mass spectrometry is suitable for the analysis of gun-powder anatomy research.

  6. Stability and modal analysis of shock/boundary layer interactions

    Science.gov (United States)

    Nichols, Joseph W.; Larsson, Johan; Bernardini, Matteo; Pirozzoli, Sergio

    2016-06-01

    The dynamics of oblique shock wave/turbulent boundary layer interactions is analyzed by mining a large-eddy simulation (LES) database for various strengths of the incoming shock. The flow dynamics is first analyzed by means of dynamic mode decomposition (DMD), which highlights the simultaneous occurrence of two types of flow modes, namely a low-frequency type associated with breathing motion of the separation bubble, accompanied by flapping motion of the reflected shock, and a high-frequency type associated with the propagation of instability waves past the interaction zone. Global linear stability analysis performed on the mean LES flow fields yields a single unstable zero-frequency mode, plus a variety of marginally stable low-frequency modes whose stability margin decreases with the strength of the interaction. The least stable linear modes are grouped into two classes, one of which bears striking resemblance to the breathing mode recovered from DMD and another class associated with revolving motion within the separation bubble. The results of the modal and linear stability analysis support the notion that low-frequency dynamics is intrinsic to the interaction zone, but some continuous forcing from the upstream boundary layer may be required to keep the system near a limit cycle. This can be modeled as a weakly damped oscillator with forcing, as in the early empirical model by Plotkin (AIAA J 13:1036-1040, 1975).

  7. Stability and modal analysis of shock/boundary layer interactions

    Science.gov (United States)

    Nichols, Joseph W.; Larsson, Johan; Bernardini, Matteo; Pirozzoli, Sergio

    2017-02-01

    The dynamics of oblique shock wave/turbulent boundary layer interactions is analyzed by mining a large-eddy simulation (LES) database for various strengths of the incoming shock. The flow dynamics is first analyzed by means of dynamic mode decomposition (DMD), which highlights the simultaneous occurrence of two types of flow modes, namely a low-frequency type associated with breathing motion of the separation bubble, accompanied by flapping motion of the reflected shock, and a high-frequency type associated with the propagation of instability waves past the interaction zone. Global linear stability analysis performed on the mean LES flow fields yields a single unstable zero-frequency mode, plus a variety of marginally stable low-frequency modes whose stability margin decreases with the strength of the interaction. The least stable linear modes are grouped into two classes, one of which bears striking resemblance to the breathing mode recovered from DMD and another class associated with revolving motion within the separation bubble. The results of the modal and linear stability analysis support the notion that low-frequency dynamics is intrinsic to the interaction zone, but some continuous forcing from the upstream boundary layer may be required to keep the system near a limit cycle. This can be modeled as a weakly damped oscillator with forcing, as in the early empirical model by Plotkin (AIAA J 13:1036-1040, 1975).

  8. Combined multivariate data analysis of high-performance thin-layer chromatography fingerprints and direct analysis in real time mass spectra for profiling of natural products like propolis.

    Science.gov (United States)

    Morlock, Gertrud E; Ristivojevic, Petar; Chernetsova, Elena S

    2014-02-07

    Sophisticated statistical tools are required to extract the full analytical power from high-performance thin-layer chromatography (HPTLC). Especially, the combination of HPTLC fingerprints (image) with chemometrics is rarely used so far. Also, the newly developed, instantaneous direct analysis in real time mass spectrometry (DART-MS) method is perspective for sample characterization and differentiation by multivariate data analysis. This is a first novel study on the differentiation of natural products using a combination of fast fingerprint techniques, like HPTLC and DART-MS, for multivariate data analysis. The results obtained by the chemometric evaluation of HPTLC and DART-MS data provided complementary information. The complexity, expense, and analysis time were significantly reduced due to the use of statistical tools for evaluation of fingerprints. The approach allowed categorizing 91 propolis samples from Germany and other locations based on their phenolic compound profile. A high level of confidence was obtained when combining orthogonal approaches (HPTLC and DART-MS) for ultrafast sample characterization. HPTLC with selective post-chromatographic derivatization provided information on polarity, functional groups and spectral properties of marker compounds, while information on possible elemental formulae of principal components (phenolic markers) was obtained by DART-MS. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Enabling Realistic Cross-Layer Analysis based on Satellite Physical Layer Traces

    CERN Document Server

    Kuhn, Nicolas; Lacan, Jerome; Boreli, Roksana; Bes, Caroline; Clarac, Laurence

    2012-01-01

    We present a solution to evaluate the performance of transport protocols as a function of link layer reliability schemes (i.e. ARQ, FEC and Hybrid ARQ) applied to satellite physical layer traces. As modelling such traces is complex and may require approximations, the use of real traces will minimise the potential for erroneous performance evaluations resulting from imperfect models. Our Trace Manager Tool (TMT) produces the corresponding link layer output, which is then used within the ns-2 network simulator via the additionally developed ns-2 interface module. We first present the analytical models for the link layer with bursty erasure packets and for the link layer reliability mechanisms with bursty erasures. Then, we present details of the TMT tool and our validation methodology, demonstrating that the selected performance metrics (recovery delay and throughput efficiency) exhibit a good match between the theoretical results and those obtained with TMT. Finally, we present results showing the impact of di...

  10. Radial transmission line analysis of multi-layer structures

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, H.; Hammons, L.

    2011-03-28

    The analysis of multi-layer beam tubes is a standard problem and involves axially propagating waves. This treatment is ill suited to a short multi-layer structure such as the present example of a ferrite covered ceramic break in the beam tube at the ERL photo-cathode electron gun. This paper demonstrates that such structure can better be treated by radial wave propagation. The theoretical method is presented and numerical results are compared with measured network analyser data and Microwave Studio generated simulations. The results confirm the concept of radial transmission lines as a valid analytical method. An Energy Recovery Linac (ERL) is being constructed at this laboratory for the purpose of research towards an envisioned Electron Ion Collider. One of the pertinent topics is damping of Higher Order Modes (HOM). In this ERL, the damping is provided by ferrite absorbers in the beam tube. A modified version thereof, a ceramic break surrounded by ferrite, is planed for the superconducting electron gun. The damper here is located at room temperature just outside of the gun. If used in a cavity chain, the ceramic break is in the vacuum tube at helium temperature whereas the ferrite is moved into the cryostat insulating vacuum allowing higher temperatures. The general properties of the ferrite HOM dampers have been published but are more detailed in this paper.

  11. Cross-Layer Design and Analysis of Downlink Communications in Cellular CDMA Systems

    Directory of Open Access Journals (Sweden)

    Sun Jin Yuan

    2006-01-01

    Full Text Available A cellular CDMA network with voice and data communications is considered. Focusing on the downlink direction, we seek for the overall performance improvement which can be achieved by cross-layer analysis and design, taking physical layer, link layer, network layer, and transport layer into account. We are concerned with the role of each single layer as well as the interaction among layers, and propose algorithms/schemes accordingly to improve the system performance. These proposals include adaptive scheduling for link layer, priority-based handoff strategy for network admission control, and an algorithm for the avoidance of TCP spurious timeouts at the transport layer. Numerical results show the performance gain of each proposed scheme over independent performance of an individual layer in the wireless mobile network. We conclude that the system performance in terms of capacity, throughput, dropping probability, outage, power efficiency, delay, and fairness can be enhanced by jointly considering the interactions across layers.

  12. Physicochemical and chromatographic method of characterization of Matricaria recutita tinctures

    Directory of Open Access Journals (Sweden)

    Jonathan Parra

    2016-02-01

    Full Text Available Context: The pharmacological activity of medicinal products containing plant materials depends on their specific components. However, these components are not characterized in their entirety in all cases. Therefore, manufacturing processes must be duly characterized and validated. Aims: To characterize a chamomile (Matricaria recutita tincture through chemometric analysis of chromatographic data in order to establish quality parameters for its production. Methods: Various chamomile tinctures were manufactured and the precision and robustness of the production process for each was verified. The physicochemical properties of the tinctures were characterized and their chromatographic digital fingerprints analysed through chemometric methods. Results: A good correlation between the physicochemical characterization and the chromatographic analysis was demonstrated. The preparation methodology was proved to be repeatable as long as the source of the plant material is not altered. Conclusions: The principal component multivariate analysis of chromatograms was a helpful and simple tool for the characterization and traceability of the production method.

  13. Parallel development of chromatographic and mass-spectrometric methods for quantitative analysis of glycation on an IgG1 monoclonal antibody.

    Science.gov (United States)

    Viski, Kornél; Gengeliczki, Zsolt; Lenkey, Krisztián; Baranyáné Ganzler, Katalin

    2016-10-01

    Monitoring post-translational modifications (PTMs) in biotherapeutics is of paramount importance. In pharmaceutical industry, chromatography with optical detection is the standard choice of quantitation of product related impurities; and mass spectrometry is used only for characterization. Parallel development of a boronate affinity chromatographic (BAC) and a mass spectrometric methods for quantitative measurement of glycation on a monoclonal antibody (mAb) shed light on the importance of certain characteristics of the individual methods. Non-specific interactions in BAC has to be suppressed with the so-called shielding reagent. We have found that excessive amount of shielding reagents in the chromatographic solvents may cause significant underestimation of glycation. Although contamination of the retained peak with the non-glycated isoforms in BAC is unavoidable, our work shows that it can be characterized and quantitated by mass spectrometry. It has been demonstrated that glycation can be measured by mass spectrometry at the intact protein level with an LOQ value of 3.0% and error bar of ±0.5%. The BAC and MS methods have been found to provide equivalent results. These methods have not been compared from these points of view before.

  14. 蒲地兰消炎口服液中板蓝根等4味药材薄层色谱鉴别%Thin-layer Chromatographic Identification of Four Chinese Herbs in Pudilan Xiaoyan Oral Liquid Such as Isatis Root

    Institute of Scientific and Technical Information of China (English)

    李亚玲; 叶云; 余德智

    2012-01-01

    Objective: To build thin-layer chromatographic identification method of Pudilan Xiaoyan oral liquid. Methods: The exclusive identification of dandelion, viola yedoensis makino, scutellaria baicalensis and radix isatidis in Pudilan Xiaoyan oral liquid by thin-layer chromatography ( HLC ). Results: The thin-layer chromatography features of each herbs is obvious, negative reference solution isn't interference. Conclusion'. The method is simple, fast, accurate results, high sensitivity, exclusive, and repeatability, which can effectively control quality of Pudilan Xiaoyan oral liquid.%目的:构建蒲地蓝消炎口服液的薄层色谱定性鉴别方法.方法:用薄层色谱法(HLC)对蒲地蓝消炎口服液中的蒲公英、苦地丁、板蓝根、黄芩进行专属定性鉴别.结果:各味药材的薄层色谱特征明显,阴性对照溶液无干扰.结论:本方法操作简便、快速、结果准确、灵敏度高、专属性强、重复性好,可有效控制蒲地蓝消炎口服液的质量.

  15. Five-descriptor model to predict the chromatographic sequence of natural compounds.

    Science.gov (United States)

    Hou, Shuying; Wang, Jinhua; Li, Zhangming; Wang, Yang; Wang, Ying; Yang, Songling; Xu, Jia; Zhu, Wenliang

    2016-03-01

    Despite the recent introduction of mass detection techniques, ultraviolet detection is still widely applied in the field of the chromatographic analysis of natural medicines. Here, a neural network cascade model consisting of nine small artificial neural network units was innovatively developed to predict the chromatographic sequence of natural compounds by integrating five molecular descriptors as the input. A total of 117 compounds of known structure were collected for model building. The order of appearance of each compound was determined in gradient chromatography. Strong linear correlation was found between the predicted and actual chromatographic position orders (Spearman's rho = 0.883, p chromatographic order of multiple compounds. A case study shows that chromatographic sequence prediction based on a neural network cascade facilitated compound identification in the chromatographic fingerprint of Radix Salvia miltiorrhiza. For natural medicines of known compound composition, our method provides a feasible means for identifying the constituents of interest when only ultraviolet detection is available.

  16. Auditing of chromatographic data.

    Science.gov (United States)

    Mabie, J T

    1998-01-01

    During a data audit, it is important to ensure that there is clear documentation and an audit trail. The Quality Assurance Unit should review all areas, including the laboratory, during the conduct of the sample analyses. The analytical methodology that is developed should be documented prior to sample analyses. This is an important document for the auditor, as it is the instrumental piece used by the laboratory personnel to maintain integrity throughout the process. It is expected that this document will give insight into the sample analysis, run controls, run sequencing, instrument parameters, and acceptance criteria for the samples. The sample analysis and all supporting documentation should be audited in conjunction with this written analytical method and any supporting Standard Operating Procedures to ensure the quality and integrity of the data.

  17. A simple 2-directional high-performance thin-layer chromatographic method for the simultaneous determination of curcumin, metanil yellow, and sudan dyes in turmeric, chili, and curry powders.

    Science.gov (United States)

    Dixit, Sumita; Khanna, Subhash K; Das, Mukul

    2008-01-01

    A method using simple extraction and 2-directional high-performance thin-layer chromatography (HPTLC) was developed for the simultaneous determination of curcumin, metanil yellow, and sudan dyes in turmeric, chili, and various mixed curry powder formulations. The method offers resolution (Rf) of turmeric pigments, namely, curcumin (0.77), demethoxycurcumin (0.69), bis(demethoxy)curcumin (0.61), and the synthetic dye metanil yellow (0.05) by the first-directional mobile phase, chloroform-methanol (9 + 1, v/v). The resolution (Rf) of sudan I (0.30) and sudan IV (0.23) was achieved by the second-directional mobile phase, toluene-hexane-acetic acid (50 + 50 + 1, v/v/v). Natural pigments of both turmeric and chili showed no interference in the detection and quantification of synthetic colors. The limit of detection and limit of quantification values for curcumin, metanil yellow, sudan I, and sudan IV were 17.39, 42.90, 15.45, and 7.01 and 52.71,130.0, 46.80, and 21.24 ng/spot, respectively. Analysis of a few market samples showed the presence of metanil yellow (1.5-4.6 mg/g), sudan I (4.8-12.1 mg/g), and sudan IV (0.9-2.0 mg/g) in loose turmeric and chili samples, whereas the curcumin content in turmeric and mixed curry powder samples ranged from 6.5 to 36.4 and from 0.3 to 1.9 mg/g, respectively. The method is relatively simple, offers reasonable sensitivity, and can be used to screen a large number of samples.

  18. Analysis of low active-pharmaceutical-ingredient signal drugs based on thin layer chromatography and surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Li, Xiao; Chen, Hui; Zhu, Qingxia; Liu, Yan; Lu, Feng

    2016-11-30

    Active pharmaceutical ingredients (API) embedded in the excipients of the formula can usually be unravelled by normal Raman spectroscopy (NRS). However, more and more drugs with low API content and/or low Raman scattering coefficient were insensitive to NRS analysis, which was for the first time defined as Low API-Signal Drugs (LASIDs) in this paper. The NRS spectra of these LASIDs were similar to their dominant excipients' profiles, such as lactose, starch, microcrystalline cellulose (MCC), etc., and were classified into three types as such. 21 out of 100 kinds of drugs were screened as LASIDs and characterized further by Raman microscopic mapping. Accordingly, we proposed a tailored solution to the qualitation and quantitation problem of these LASIDs, using surface-enhanced Raman spectroscopic (SERS) detection on the thin layer chromatographic (TLC) plate both in situ and after-separation. Experimental conditions and parameters including TLC support matrix, SERS substrate, detection mode, similarity threshold, internal standard, etc., were optimized. All LASIDs were satisfactorily identified and the quantitation results agreed well with those of high performance liquid chromatography (HPLC). For some structural analogues of LASIDs, although they presented highly similar SERS spectra and were tough to distinguish even with Raman microscopic mapping, they could be successfully discriminated from each other by coupling SERS (with portable Raman spectrometer) with TLC. These results demonstrated that the proposed solution could be employed to detect the LASIDs with high accuracy and cost-effectiveness. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Towards unsupervised analysis of second-order chromatographic data: automated selection of number of components in multivariate curve-resolution methods.

    Science.gov (United States)

    Vivó-Truyols, G; Torres-Lapasió, J R; García-Alvarez-Coque, M C; Schoenmakers, P J

    2007-07-27

    A method to apply multivariate curve-resolution unattendedly is presented. The algorithm is suitable to perform deconvolution of two-way data (e.g. retrieving the individual elution profiles and spectra of co-eluting compounds from signals obtained from a chromatograph equipped with multiple-channel detection: LC-DAD or GC-MS). The method is especially adequate to achieve the advantages of deconvolution approaches when huge amounts of data are present and manual application of multivariate techniques is too time-consuming. The philosophy of the algorithm is to mimic the reactions of an expert user when applying the orthogonal projection approach--multivariate curve-resolution techniques. Basically, the method establishes a way to check the number of significant components in the data matrix. The performance of the method was superior to the Malinowski F-test. The algorithm was tested with HPLC-DAD signals.

  20. [Analysis of writing age of ballpoint pen ink by thin-layer chromatography].

    Science.gov (United States)

    Zhao, P C; Wang, Y J; Cui, L; Shi, X F; Wang, Y H

    2001-07-01

    A method based on using a thin-layer chromatographic method (TLC) for determining changes in dye of ballpoint pen ink developed with writing age. An ink drawn line of 1 cm in length was cut and placed in Eppendorf tube. Extraction was performed with 20 microL ethanol at room temperature for 15 min, and heated in steambath for 10 min. The ethanol solution(4 microL) containing the extracted dyes was then spotted on TLC plate by syringe after cooling. The ballpoint pen ink spots were eluted in a solvent of isopropyl alcohol. Using TLC scanner, the spots on TLC plate were scanned at 580 nm. The relations between ratio of peak heights and writing age were attained. Thus, the information on relative writing age can be obtained. And, the powerful evidence for identifying the age of ballpoint pen ink is provided by this method in the field of forensic science.

  1. Gas chromatography for in situ analysis of a cometary nucleus. II. Analysis of permanent gases and light hydrocarbons with a carbon molecular sieve porous layer open tubular column.

    Science.gov (United States)

    Szopa, C; Sternberg, R; Coscia, D; Raulin, F; Vidal-Madjar, C

    2000-12-22

    Considering the severe constraints of space instrumentation, a great improvement for the in situ gas chromatographic (GC) determination of permanent and noble gases in a cometary nucleus is the use of a new carbon molecular sieve porous layer open tubular (PLOT) column called Carbobond. No exhaustive data dealing with this column being available, studies were carried out to entirely characterize its analytical performances, especially when used under the operating conditions of the cometary sampling and composition (COSAC) experiment of the European Space Agency (ESA) Rosetta space mission to be launched in 2003 for a rendezvous with comet 46 P/Wirtanen in 2011. The high efficiency and speed of analysis of this column at both atmospheric and vacuum outlet column pressure is demonstrated, and the kinetic mass transfer contribution of this carbon molecular sieve adsorbent is calculated. Besides, differential adsorption enthalpies of several gases and light hydrocarbons were determined from the variation of retention volume with temperature. The data indicate close adsorption behaviors on the Carbobond porous layer adsorbent and on the carbon molecular sieve Carboxen support used to prepare the packed columns. Moreover, taking into account the in situ operating conditions of the experiment, a study of two columns with different porous layer thicknesses allowed one to optimize the separation of the target components and to select the column parameters compatible with the instrument constraints. Comparison with columns of similar selectivity shows that these capillary columns are the first ones able to perform the same work as the packed and micro-packed columns dedicated to the separation of this range of compounds in GC space exploration.

  2. Analysis of layer-by-layer thin-film oxide growth using RHEED and Atomic Force Microscopy

    Science.gov (United States)

    Adler, Eli; Sullivan, M. C.; Gutierrez-Llorente, Araceli; Joress, H.; Woll, A.; Brock, J. D.

    2015-03-01

    Reflection high energy electron diffraction (RHEED) is commonly used as an in situ analysis tool for layer-by-layer thin-film growth. Atomic force microscopy is an equally common ex situ tool for analysis of the film surface, providing visual evidence of the surface morphology. During growth, the RHEED intensity oscillates as the film surface changes in roughness. It is often assumed that the maxima of the RHEED oscillations signify a complete layer, however, the oscillations in oxide systems can be misleading. Thus, using only the RHEED maxima is insufficient. X-ray reflectivity can also be used to analyze growth, as the intensity oscillates in phase with the smoothness of the surface. Using x-ray reflectivity to determine the thin film layer deposition, we grew three films where the x-ray and RHEED oscillations were nearly exactly out of phase and halted deposition at different points in the growth. Pre-growth and post-growth AFM images emphasize the fact that the maxima in RHEED are not a justification for determining layer completion. Work conducted at the Cornell High Energy Synchrotron Source (CHESS) supported by NSF Awards DMR-1332208 and DMR-0936384 and the Cornell Center for Materials Research Shared Facilities are supported through DMR-1120296.

  3. Thermal Analysis of Low Layer Density Multilayer Insulation Test Results

    Science.gov (United States)

    Johnson, Wesley L.

    2011-01-01

    Investigation of the thermal performance of low layer density multilayer insulations is important for designing long-duration space exploration missions involving the storage of cryogenic propellants. Theoretical calculations show an analytical optimal layer density, as widely reported in the literature. However, the appropriate test data by which to evaluate these calculations have been only recently obtained. As part of a recent research project, NASA procured several multilayer insulation test coupons for calorimeter testing. These coupons were configured to allow for the layer density to be varied from 0.5 to 2.6 layer/mm. The coupon testing was completed using the cylindrical Cryostat-l00 apparatus by the Cryogenics Test Laboratory at Kennedy Space Center. The results show the properties of the insulation as a function of layer density for multiple points. Overlaying these new results with data from the literature reveals a minimum layer density; however, the value is higher than predicted. Additionally, the data show that the transition region between high vacuum and no vacuum is dependent on the spacing of the reflective layers. Historically this spacing has not been taken into account as thermal performance was calculated as a function of pressure and temperature only; however the recent testing shows that the data is dependent on the Knudsen number which takes into account pressure, temperature, and layer spacing. These results aid in the understanding of the performance parameters of MLI and help to complete the body of literature on the topic.

  4. ANALYSIS OF MICROBUCKLING FOR MONOMOLECULAR LAYERS ADHERING TO A SUBSTRATE

    Institute of Scientific and Technical Information of China (English)

    张田忠; 郭万林; 李国强

    2002-01-01

    A two-dimensional linear spring model is established to study themicrobuckling of a plane monomolecular layer adhering to a substrate. The modelis for the layer subjected to a compressive load having an arbitrary angle with thechemical bond of the layer. The effects of the load angle, the strength of adhesionand the bending stiffness and shearing stiffness (the capability of resisting transversebending and in-plane shearing) of the layer on the minimal buckling force and thecritical buckling mode are discussed. It is found that the minimal buckling forceincreases with increasing load angle and, for a given bending stiffness, increases withincreasing strength of adhesion and decreasing shearing stiffness. Furthermore, acritical condition under which the buckling of the layer can just occur is obtained,which is helpful to avoid buckling in an engineering application.

  5. Performance Analysis of MAC Layer Protocols in Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    Hameeza Ahmed

    2014-10-01

    Full Text Available Media Access Control (MAC layer protocols have a critical role in making a typical Wireless Sensor Network (WSN more reliable and efficient. Choice of MAC layer protocol and other factors including number of nodes, mobility, traffic rate and playground size dictates the performance of a particular WSN. In this paper, the performance of an experimental WSN is evaluated using different MAC layer protocols. In this experiment, a WSN is created using OMNeT++ MiXiM network simulator and its performance in terms of packet delivery ratio and mean latency is evaluated. The simulation results show that IEEE 802.11 MAC layer protocol performs better than CSMA, B-MAC and IEEE 802.15.4 MAC layer protocols. In the considered scenario, IEEE 802.15.4 is ranked second in performance, followed by CSMA and B-MAC.

  6. Sensitivity analysis of bi-layered ceramic dental restorations.

    Science.gov (United States)

    Zhang, Zhongpu; Zhou, Shiwei; Li, Qing; Li, Wei; Swain, Michael V

    2012-02-01

    The reliability and longevity of ceramic prostheses have become a major concern. The existing studies have focused on some critical issues from clinical perspectives, but more researches are needed to address fundamental sciences and fabrication issues to ensure the longevity and durability of ceramic prostheses. The aim of this paper was to explore how "sensitive" the thermal and mechanical responses, in terms of changes in temperature and thermal residual stress of the bi-layered ceramic systems and crown models will be with respect to the perturbation of the design variables chosen (e.g. layer thickness and heat transfer coefficient) in a quantitative way. In this study, three bi-layered ceramic models with different geometries are considered: (i) a simple bi-layered plate, (ii) a simple bi-layer triangle, and (iii) an axisymmetric bi-layered crown. The layer thickness and convective heat transfer coefficient (or cooling rate) seem to be more sensitive for the porcelain fused on zirconia substrate models. The resultant sensitivities indicate a critical importance of the heat transfer coefficient and thickness ratio of core to veneer on the temperature distributions and residual stresses in each model. The findings provide a quantitative basis for assessing the effects of fabrication uncertainties and optimizing the design of ceramic prostheses. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Optimisation and validation of ultra-high performance liquid chromatographic-tandem mass spectrometry method for qualitative and quantitative analysis of potato steroidal alkaloids.

    Science.gov (United States)

    Hossain, Mohammad B; Rai, Dilip K; Brunton, Nigel P

    2015-08-01

    An ultra-high performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS) method for quantification of potato steroidal alkaloids, namely α-solanine, α-chaconine, solanidine and demissidine was developed and validated. Three different column chemistries, i.e. ethylene bridged hybrid (BEH) C18, hydrophilic lipophilic interaction and amide columns, were assessed. The BEH C18 column showed best separation and sensitivity for the alkaloids. Validation data (inter-day and intra-day combined) for accuracy and recovery ranged from 94.3 to 107.7% and 97.0 to 103.5%, respectively. The accuracy data were within the acceptable range of 15% as outlined in the United States Food and Drug Administration (USFDA) guidelines. The recovery data were consistent and reproducible with a coefficient of variation (CV) ranging from 6.2 to 9.7%. In addition, precision of the method also met the criteria of the USFDA with CV values lower than 15% even at lower limit of quantification (LLOQ), while the permissible variation is considered acceptable below 20%. The limit of detection and LLOQ of the four alkaloids were in the range of 0.001-0.004μg/mL whereas the linearities of the standard curves were between 0.980 and 0.995.

  8. Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

    Science.gov (United States)

    Martínez-Bernett, D.; Silva-Granados, A.; Correa-Torres, S. N.; Herrera, A.

    2016-02-01

    It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution.

  9. Performance Analysis of "WBC over DVB-H" Link Layer

    Directory of Open Access Journals (Sweden)

    Ji Zhanlin

    2010-01-01

    Full Text Available This paper presents two novel smart cross-layer error-control coding schemes for improving the error protection of service advertisements that are broadcast to mobile terminals on wireless billboard channels (WBCs established over a digital video broadcast-handheld (DVB-H infrastructure. These are the smart section erasure (SSE and smart transport stream erasure (STSE schemes, which are jointly executed by the link layer and service layer cross-layer algorithms. The new schemes are analysed and compared to existing schemes. The solution enables the "WBC over DVB-H" system to operate with good flexibility, and in a more reliable way and with greater throughput efficiency than the standard IP datacasting supported in DVB-H.

  10. Analysis of diabatic flow modification in the internal boundary layer

    DEFF Research Database (Denmark)

    Floors, Rogier; Gryning, Sven-Erik; Pena Diaz, Alfredo

    2011-01-01

    is controlled by a combination of both downstream and upstream stability and surface roughness conditions. A model based on a diffusion analogy is able to predict the internal boundary layer height well. Modeling the neutral and long-term wind profile with a 3 layer linear interpolation scheme gives good......Measurements at two meteorological masts in Denmark, Horns Rev in the sea and Høvsøre near the coastline on land, are used to analyze the behaviour of the flow after a smooth-to-rough change in surface conditions. The study shows that the wind profile within the internal boundary layer...... results at Høvsøre. Based on a comparison with a numerical model and the measurements, the constants in the interpolation scheme are slightly adjusted, which yields an improvement for the description of the wind profile in the internal boundary layer....

  11. Compression analysis of rectangular elastic layers bonded between rigid plates

    Energy Technology Data Exchange (ETDEWEB)

    Hsiang-Chuan Tsai [National Taiwan University of Science and Technology, Taipei (China). Dept. of Construction Engineering

    2005-06-01

    An elastic layer bonded between two rigid plates has higher compression stiffness than the elastic layer without bonding. While the finite element method can be applied to calculate the stiffness, the compression stiffness of bonded rectangular layers derived through a theoretical approach in this paper provides a convenient way for parametric study. Based on two kinematics assumptions, the governing equation for the mean pressure is derived from the equilibrium equations. Using the approximate shear boundary condition, the mean pressure is solved and the compression stiffness of the bonded rectangular layer is then established in an explicit single-series form. Through the solved pressure, the horizontal displacements are derived from the corresponding equilibrium equations, from which the shear stress on the bonding surface can be found. It is found that the effect of the rectangular aspect on the compression stiffness is significant only when Poisson's ratio is near 0.5. For the smaller Poisson's ratio, the compression stiffness of the rectangular layer can be approximated by the formula for the infinite-strip layer of the same shape factor. (author)

  12. An Analysis of the Characteristics of the Thermal Boundary Layer in Power Law Fluid

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper presents a theoretical analysis of the heat transfer for the boundary layer flow on a continuous moving surface in power law fluid. The expressions of the thermal boundary layer thickness with the different heat conductivity coefficients are obtained according to the theory of the dimensional analysis of fluid dynamics and heat transfer. And the numerical results of CFD agree well with the proposed expressions. The estimate formulas can be successfully applied to giving the thermal boundary layer thickness.

  13. Chondrocyte Behavior on Micropatterns Fabricated Using Layer-by-Layer Lift-Off: Morphological Analysis

    Directory of Open Access Journals (Sweden)

    Jameel Shaik

    2013-01-01

    Full Text Available Cell patterning has emerged as an elegant tool in developing cellular arrays, bioreactors, biosensors, and lab-on-chip devices and for use in engineering neotissue for repair or regeneration. In this study, micropatterned surfaces were created using the layer-by-layer lift-off (LbL-LO method for analyzing canine chondrocytes response to patterned substrates. Five materials were chosen based on our previous studies. These included: poly(dimethyldiallylammonium chloride (PDDA, poly(ethyleneimine (PEI, poly(styrene sulfonate (PSS, collagen, and chondroitin sulfate (CS. The substrates were patterned with these five different materials, in five and ten bilayers, resulting in the following multilayer nanofilm architectures: (PSS/PDDA5, (PSS/PDDA10; (CS/PEI4/CS, (CS/PEI9/CS; (PSS/PEI5, (PSS/PEI10; (PSS/Collagen5, (PSS/Collagen10; (PSS/PEI4/PSS, (PSS/PEI9/PSS. Cell characterization studies were used to assess the viability, longevity, and cellular response to the configured patterned multilayer architectures. The cumulative cell characterization data suggests that cell viability, longevity, and functionality were enhanced on micropatterned PEI, PSS, collagen, and CS multilayer nanofilms suggesting their possible use in biomedical applications.

  14. Plasmon analysis and homogenization in plane layered photonic crystals and hyperbolic metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Davidovich, M. V., E-mail: davidovichmv@info.sgu.ru [Saratov State University (Russian Federation)

    2016-12-15

    Dispersion equations are obtained and analysis and homogenization are carried out in periodic and quasiperiodic plane layered structures consisting of alternating dielectric layers, metal and dielectric layers, as well as graphene sheets and dielectric (SiO{sub 2}) layers. Situations are considered when these structures acquire the properties of hyperbolic metamaterials (HMMs), i.e., materials the real parts of whose effective permittivity tensor have opposite signs. It is shown that the application of solely dielectric layers is more promising in the context of reducing losses.

  15. Plasmon analysis and homogenization in plane layered photonic crystals and hyperbolic metamaterials

    Science.gov (United States)

    Davidovich, M. V.

    2016-12-01

    Dispersion equations are obtained and analysis and homogenization are carried out in periodic and quasiperiodic plane layered structures consisting of alternating dielectric layers, metal and dielectric layers, as well as graphene sheets and dielectric (SiO2) layers. Situations are considered when these structures acquire the properties of hyperbolic metamaterials (HMMs), i.e., materials the real parts of whose effective permittivity tensor have opposite signs. It is shown that the application of solely dielectric layers is more promising in the context of reducing losses.

  16. Analysis of plasmons and homogenization in a flat-layered photonic crystals and hyperbolic metamaterials

    Science.gov (United States)

    Davidovich, Mikhael V.

    2016-04-01

    The dispersion equation and the analysis and homogenization in periodic and quasiperiodic plane layered structures with alternating dielectric layers of metal and dielectric layers, as well as a graphene sheet and SiO2 layers have been investigated. The cases are considered when these patterns become the properties of hyperbolic metamaterials, i.e., having different signs of the real parts of the tensor components of the effective dielectric constant. It is shown that usage only dielectric layers is perspective in reducing losses.

  17. Modeling and analysis of ultrasound propagation in layered-medium

    Science.gov (United States)

    Dey, Joyoni

    For many medical applications of ultrasonic devices, it is often of interest to determine the distortion of ultrasound waves due to tissue layers of fat and muscle. Bending of the acoustic rays due to refraction at intermediate layers degrades image resolution, causes distortion and other artifacts in ultrasound images. In this work, ultrasound propagation in layered media is modeled analytically. Closed-form expressions are presented for the field amplitude of spherical waves for the following cases: (1)transmission through a three-layered media, (2)extension to transmission through multi-layered medium, (3)a special case of modeling received echoes from an interface through two layers. In our derivations, ray-acoustic approximations have been assumed. We show that ray-acoustic approximations are valid for wavelengths (relative to medium layer dimensions) of interest. The field amplitude is calculated by taking differentials of the rays to form flux tubes and algebraically calculating the ratios of flux-tube areas. We also take into account the frequency dependent attenuation due to absorption and backscattering loss in the media. The interfaces between media are assumed to be arbitrary shaped, but can be broken up into small planar segments. The resulting response can be extended to different aperture geometries and different beam formations by delaying and summing the result for the Huygen waves emanating from the points forming the aperture. We have considered the inversion problem for the case of two layers on a reflective interface, where the layers are planar and parallel to the aperture. We showed that it is better to use demodulated versions of signal outputs than use the raw signals themselves to avoid local minima at regular intervals around the global minimum. Validation experiments were performed using custom made tissue mimicking phantoms of fat and muscle and a steel- block. We fit the forward-model to the experimental data using Levenberg

  18. Analysis of tetrodotoxin by hyphenated chromatographic techniques%多种色谱联用技术分析替曲朵辛

    Institute of Scientific and Technical Information of China (English)

    代秀梅; 于风平; 张启明

    2013-01-01

    目的:建立替曲朵辛原料药含量及有关物质的测定方法,并对有关物质的结构进行分析.方法:采用HPLC法测定替曲朵辛原料药含量及有关物质,采用UPLC-UV-MS/MS和LC-NMR联用技术对含量最高的杂质9的结构进行分析.结果:重复性好,替曲朵辛浓度在0.294~44.16 μg· mL-1范围内线性关系良好(r =0.9999),有关物质中最大杂质为4,9,10,11二脱水河豚毒素.结论:本方法操作简便,结果准确,可作为替曲朵辛原料药含量测定和有关物质检查的方法.%Objective:To establish a hyphenated chromatographic method for content determination of tetrodotoxin (TTX) raw medicine and related substances and to analyze the structure of related substances.Methods:HPLC was used to determin the content of tetrodotoxin mw medicine and related substances,and UPLC-UV-MS/MS and LC-NMR were used to study the structure of related substances.Results:There was a good linear relationship for tetrodotoxin in the range of 0.294-44.16 μg · mL-1 (r =0.9999).The impurity of the highest content was 4,9,10,11-dianhydro-TTX.Conclusion:The method is simple,accurate,and well reproducible which can be applied to content determination of Tet rodotoxin raw medicine and related substances.

  19. Well test analysis for wells producing layered reservoirs with crossflow

    Energy Technology Data Exchange (ETDEWEB)

    Prijambodo, R.; Raghavan, R.; Reynolds, A.C.

    1981-01-01

    The pressure response of a well producing a two-layer reservoir with crossflow is examined. It is shown that the flowing pressure response of a well at early times can be divided into three flow periods. The first period is one in which the reservoir behaves as if it were a stratified system (no-crossflow). This period is followed by a transitional period. During the third period, the reservoir can be described by an equivalent single-layer system. The influence of the skin regions is presented. The significance of the estimate of the skin factor obtained from a pressure test is discussed. It is shown that the nature and magnitude of the skin regions and the size of the reservoir determine the applicability of procedures that are based on single-layer systems. 17 refs.

  20. Headspace chromatographic determination of water pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Otson, R.; Williams, D.T.

    1982-05-01

    A readily constructed, automated purging assembly, on-column trapping, and simultaneous use of flame ionization and electrolytic conductivity detectors were applied to develop a dynamic headspace gas chromatographic technique which was evaluated for the determination of 42 organic polluants in water. Detection limits of <1 ..mu..g/L and linear plots of peak area against concentration in the range 0.25-16 ..mu..g/L were obtained for 32 compounds. At aqueous concentrations of 4 and 16 ..mu..g/L, peak area precision of <10% relative standard deviation (RSD) for triplicate sample analysis and purging efficiencies of >75% were generally obtained. Storage of aqueous composite standard solutions at 4 and 16 ..mu..g/L for 6 weeks at 4/sup 0/C did not usually affect analytical results by more than +/- 15%.

  1. Quality assessment of Cinnamomi Ramulus by the simultaneous analysis of multiple active components using high-performance thin-layer chromatography and high-performance liquid chromatography.

    Science.gov (United States)

    Wu, Xiaoxue; He, Jiao; Xu, Huarong; Bi, Kaishun; Li, Qing

    2014-09-01

    A novel and improved method for the quality assessment of Cinnamomi Ramulus was developed and completely validated. The method was established using fingerprint technology and simultaneous quantitative determination of six main marker compounds including coumarin, cinnamic alcohol, cinnamic acid, 2-methoxy cinnamic acid, cinnamaldehyde, and 2-methoxy cinnamaldehyde in the herbal medicine for the first time. A newly developed high-performance thin-layer chromatography method, which achieved simultaneous definition of five marker components by comparing the colors and retardation factor values of the bands in high-performance thin-layer chromatography, was first used for the authentication of Cinnamomi Ramulus. The fingerprints of 26 batches of herbal samples from different regions of China showed very similar chromatographic patterns that were evaluated by similarity analysis and hierarchical clustering analysis. In addition, six marker compounds were simultaneously determined using single standard to determine multiple components by the relative response factors. Compared with the external standard method, the new quantitative method was validated to determine multiple compounds in 26 batches of Cinnamomi Ramulus samples. All results demonstrated that the simple and rapid method could be effectively utilized for the quality control of Cinnamomi Ramulus. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Transient Analysis Used to Study Thermal Radiation Effects in Single and Composite Semitransparent Layers

    Science.gov (United States)

    1996-01-01

    In a continuing in-house program at the NASA Lewis Research Center, analytical and numerical methods are being developed to apply radiative analysis to predict transient temperature distributions and heat flows in partially transmitting materials. Results have been obtained for a single plane layer, and a transient analysis is being developed for a two-layer composite where each layer has a different refractive index. Because the ceramic refractive indices are larger than one, internal reflections are produced at the surfaces and at the internal interface. Reflections tend to distribute energy within a layer, and this affects the transient temperature distributions.

  3. Ratiometric analysis of in vivo retinal layer thicknesses in multiple sclerosis

    Science.gov (United States)

    Bhaduri, Basanta; Nolan, Ryan M.; Shelton, Ryan L.; Pilutti, Lara A.; Motl, Robert W.; Boppart, Stephen A.

    2016-09-01

    We performed ratiometric analysis of retinal optical coherence tomography images for the first time in multiple sclerosis (MS) patients. The ratiometric analysis identified differences in several retinal layer thickness ratios in the cohort of MS subjects without a history of optic neuritis (ON) compared to healthy control (HC) subjects, and there was no difference in standard retinal nerve fiber layer thickness (RNFLT). The difference in such ratios between HC subjects and those with mild MS-disability, without a difference in RNFLT, further suggests the possibility of using layer ratiometric analysis for detecting early retinal changes in MS. Ratiometric analysis may be useful and potentially more sensitive for detecting disease changes in MS.

  4. Well test analysis for wells producing layered reservoirs with crossflow

    Energy Technology Data Exchange (ETDEWEB)

    Raghavan, R.; Prijambodo, R.; Reynolds, A.C.

    1985-06-01

    The pressure response of a well producing a two-layer reservoir with crossflow is examined. Virtually all studies on the response of a well in multilayered systems with crossflow claim that after a few hours of production these systems behave as if they are single-layer systems. In this study, the authors show that the flowing pressure response of a well at early times can be divided into three flow periods. The first period is one in which the reservoir behaves as if it were a stratified (no-crossflow) system. This period is followed by a transitional period. The response of the well during this period depends on the contrast in horizontal permeabilities and on the degree of communication between the layers. During the third period, the reservoir can be described by an equivalent single-layer system. An examination of the time ranges of the various flow periods indicates that, unless tests are designed properly, most of the interpretable pressure buildup data would be measured during the time the well response is influenced by the transitional period. The influence of the skin regions on the well response is examined. The significance of the estimate of the skin factor obtained from a pressure test is discussed. The authors show that the nature and the magnitude of the skin regions and the size of the reservoir determine the applicability of conventional semilog procedures to systems with interlayer communication.

  5. Scanning electron microscopy and dentinal permeability analysis of smear layer.

    Science.gov (United States)

    Prati, C; Mongiorgi, R; Pashley, D H; Riva di Sanseverino, L

    1991-05-01

    The aim of the present study was to evaluate the surface morphology and the permeability of dentine after different acid treatments: polyacrylic acid, maleic acid, phosphoric acid and saline solution as control. Dentine permeability was expressed as hydraulic conductance. All the acid treatments removed the smear layer and increased the dentine permeability.

  6. Local Structure Analysis of Materials for Solar Cell Absorber Layer

    OpenAIRE

    Jewell, Leila Elizabeth

    2016-01-01

    This dissertation examines solar cell absorber materials that have the potential to replace silicon in solar cells, including several copper-based sulfides and perovskites. Earth-abundant absorbers such as these become even more cost-effective when used in a nanostructured solar cell. Atomic layer deposition (ALD) and chemical vapor deposition (CVD) deposit highly conformal films and hence are important tools for developing extremely thin absorber solar cells with scalability. Thus, the prima...

  7. Cross-Layer Cloud Performance Monitoring, Analysis and Recovery

    OpenAIRE

    Mdhaffar, Afef

    2015-01-01

    The basic idea of Cloud computing is to offer software and hardware resources as services. These services are provided at different layers: Software (Software as a Service: SaaS), Platform (Platform as a Service: PaaS) and Infrastructure (Infrastructure as a Service: IaaS). In such a complex environment, performance issues are quite likely and rather the norm than the exception. Consequently, performance-related problems may ...

  8. Thermographic analysis of turbulent non-isothermal water boundary layer

    CERN Document Server

    Znamenskaya, Irina A

    2015-01-01

    The paper is devoted to the investigation of the turbulent water boundary layer in the jet mixing flows using high-speed infrared (IR) thermography. Two turbulent mixing processes were studied: a submerged water jet impinging on a flat surface and two intersecting jets in a round disc-shaped vessel. An infrared camera (FLIR Systems SC7700) was focused on the window transparent for IR radiation; it provided high-speed recordings of heat fluxes from a thin water layer close to the window. Temperature versus time curves at different points of water boundary layer near the wall surface were acquired using the IR camera with the recording frequency of 100 Hz. The time of recording varied from 3 till 20 min. The power spectra for the temperature fluctuations at different points on the hot-cold water mixing zone were calculated using the Fast Fourier Transform algorithm. The obtained spectral behavior was compared to the Kolmogorov "-5/3 spectrum" (a direct energy cascade) and the dual-cascade scenario predicted for...

  9. Analysis of the transfer function for layered piezoelectric ultrasonic sensors

    Directory of Open Access Journals (Sweden)

    E. Gutiérrrez-Reyes

    2017-06-01

    Full Text Available We model theoretically the voltage response to an acoustic pulse of a multilayer system forming a low noise capacitive sensor including a Polyvinylidene Fluoride piezoelectric film. First we model a generic piezoelectric detector consisting of a piezoelectric film between two metallic electrodes that are the responsible to convert the acoustic signal into a voltage signal. Then we calculate the pressure-to-voltage transfer function for a N-layer piezo-electric capacitor detector, allowing to study the effects of the electrode and protective layers thickness in typical layered piezoelectric sensors. The derived transfer function, when multiplied by the Fourier transform of the incident acoustic pulse, gives the voltage electric response in the frequency domain. An important concern regarding the transfer function is that it may have zeros at specific frequencies, and thus inverting the voltage Fourier transform of the pulse to recover the pressure signal in the time domain is not always, in principle, possible. Our formulas can be used to predict the existence and locations of such zeroes. We illustrate the use of the transfer function by predicting the electric signal generated at a multilayer piezoelectric sensor to an ultrasonic pulse generated photoacoustically by a laser pulse at a three media system with impedance mismatch. This theoretical calculations are compared with our own experimental measurements.

  10. Assessment of antioxidant activity in Victorian marine algal extracts using high performance thin-layer chromatography and multivariate analysis.

    Science.gov (United States)

    Agatonovic-Kustrin, Snezana; Morton, David W; Ristivojević, Petar

    2016-10-14

    The aim of this study was to develop and validate a rapid and simple high performance thin layer chromatographic (HPTLC) method to screen for antioxidant activity in algal samples. 16 algal species were collected from local Victorian beaches. Fucoxanthin, one of the most abundant marine carotenoids was quantified directly from the HPTLC plates before derivatization, while derivatization either with 2,2-diphenyl-1-picrylhydrazyl (DPPH) or ferric chloride (FeCl3) was used to analyze antioxidants in marine algae, based on their ability to scavenge non biological stable free radical (DPPH) or to chelate iron ions. Principal component analysis of obtained HPTLC fingerprints has classified algae species into 5 groups according to their chemical/antioxidant profiles. The investigated brown algae samples were found to be rich in non-and moderate-polar compounds and phenolic compounds with antioxidant activity. Most of the phenolic iron chelators also have shown free radical scavenging activity. Strong positive and significant correlations between total phenolic content and DPPH radical scavenging activity showed that, phenolic compounds, including flavonoids are the main contributors of antioxidant activity in these species. The results suggest that certain brown algae possess significantly higher antioxidant potential when compared to red or green algae and could be considered for future applications in medicine, dietary supplements, cosmetics or food industries. Cystophora monilifera extract was found to have the highest antioxidant concentration, followed by Zonaria angustata, Cystophora pectinate, Codium fragile, and Cystophora pectinata. Fucoxanthin was found mainly in the brown algae species. The proposed methods provide an edge in terms of screening for antioxidants and quantification of antioxidant constituents in complex mixtures. The current application also demonstrates flexibility and versatility of a standard HPTLC system in the drug discovery. Proposed

  11. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Ying Liu

    2004-12-19

    My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were able to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic

  12. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    My graduate research has focused on separation science and bioanalytical analysis, which emphasized in method development. It includes three major areas: enantiomeric separations using high performance liquid chromatography (HPLC), Super/subcritical fluid chromatography (SFC), and capillary electrophoresis (CE); drug-protein binding behavior studies using CE; and carbohydrate analysis using liquid chromatograph-electrospray ionization mass spectrometry (LC-ESI-MS). Enantiomeric separations continue to be extremely important in the pharmaceutical industry. An in-depth evaluation of the enantiomeric separation capabilities of macrocyclic glycopeptides CSPs with SFC mobile phases was investigated using a set of over 100 chiral compounds. It was found that the macrocyclic based CSPs were able to separate enantiomers of various compounds with different polarities and functionalities. Seventy percent of all separations were achieved in less than 4 min due to the high flow rate (4.0 ml/min) that can be used in SFC. Drug-protein binding is an important process in determining the activity and fate of a drug once it enters the body. Two drug/protein systems have been studied using frontal analysis CE method. More sensitive fluorescence detection was introduced in this assay, which overcame the problem of low sensitivity that is common when using UV detection for drug-protein studies. In addition, the first usage of an argon ion laser with 257 nm beam coupled with CCD camera as a frontal analysis detection method enabled the simultaneous observation of drug fluorescence as well as the protein fluorescence. LC-ESI-MS was used for the separation and characterization of underivatized oligosaccharide mixtures. With the limits of detection as low as 50 picograms, all individual components of oligosaccharide mixtures (up to 11 glucose-units long) were baseline resolved on a Cyclobond I 2000 column and detected using ESI-MS. This system is characterized by high chromatographic

  13. Thin Layer Chromatography-High Performance Liquid Chromatographic Method for the Determination of Sudan Red in Food%薄层层析-高效液相色谱法测定食品中苏丹红

    Institute of Scientific and Technical Information of China (English)

    李春香; 黄坚; 马慧雪; 张祥

    2011-01-01

    The new method of determining banned additives in the food such as Sudan red Ⅰ and Ⅱ was established with thin layer chromatography(TLC) and high performance liquid chromatography(HPLC) two methods combined.Sudan red and impurities can be separated by silica gel plate.Under the condition of chromatography in setting,the concentration in the 0.1~20.0 μg/mL range,the peak areas(Y) and concentration(X) present good linear relationship,Sudan red Ⅰ,Ⅱ regression equations Y1=-18785+138962X,Y2=-2623+131432X.Correlation coefficient R1=0.9997,R2=0.9998.Its application of determing the Sudan red Ⅰ and Ⅱ in chili powder,chili oil,and tomato sauce was studied,and got the detection limit of 0.024 μg/g,0.027 μg/g,respectively.%建立了薄层层析-高效液相色谱联合技术测定食品中违禁添加物苏丹红Ⅰ、Ⅱ的新方法。采用硅胶板将苏丹红与杂质分离,在设定的色谱条件下测得浓度在0.1~20.0μg/mL范围内,峰面积(Y)与浓度(X)呈良好线性关系,苏丹红Ⅰ、的回归方程为Y1=-18785+138962X,Y2=-2623+131432X,相关系数R1=0.9997,R2=0.9998。将该法应用于辣椒粉、辣椒油、番茄酱等中的苏丹红Ⅰ、Ⅱ的检测。其检出限分别为0.024μg/g0、.027μg/g。

  14. Comparative study of Passiflora taxa leaves: II. A chromatographic profile

    Directory of Open Access Journals (Sweden)

    Luma Wosch

    Full Text Available ABSTRACT Popularly known as passion fruit, some species of the genus Passiflora are widely used in folk medicines, such as sedatives and tranquilizers in many countries. Although these plants are employed for the same purposes, research with different species of Passiflora has indicated their heterogeneous chemical compositions. Since different chemical compositions can result in varying degrees of therapeutic efficiency, quality control based on the chemical constituents of each species is essential. To that end, the aim of this study was to compare pharmacognostically species of Passiflora in order to establish a chromatographic profile for the quality control of drugs in herbal medicines containing passion fruit. The study was conducted by collecting samples of leaves from twelve Passiflora taxa (i.e., ten species and two forms of P. edulis – P. actinia, P. alata, P. amethystina, P. capsularis, P. cincinnata, P. edulis f. flavicarpa, P. edulis f. edulis, P. incarnata, P. morifolia, P. urnifolia, P. coccinea, and P. setacea – from different locations and obtaining their chromatographic profiles via thin-layer chromatography and high-performance liquid chromatography. Both methods used the flavonoid C-glycosides isoorientin, orientin, vitexin, and isovitexin as reference compounds and could ultimately establish specific profiles for each species. The chromatographic analyses discussed here can be used to assist in determining the quality and authenticity of herbal drugs derived from Passiflora species.

  15. Measurement of a thin layers thickness using independent component analysis of ground penetrating radar data

    Institute of Scientific and Technical Information of China (English)

    LI Xiang-tang; ZHANG Xiao-ning; WANG Duan-yi

    2008-01-01

    To detect overlapped echoes due to the thin pavement layers, we present a thickness measurement approach for the very thin layer of pavement structures. The term "thin" is relative to the incident wavelength or pulse. By means of independent component analysis of noisy signals received by a single radar sensor, the over-lapped echoes can be successfully separated. Once the echoes from the top and bottom side of a thin layer have been separated, the time delay and the layer thickness determination follow immediately. Results of the simula-tion and real data re fy the feasibility of the presented method.

  16. Chromatographic and computational assessment of lipophilicity using sum of ranking differences and generalized pair-correlation.

    Science.gov (United States)

    Andrić, Filip; Héberger, Károly

    2015-02-06

    Lipophilicity (logP) represents one of the most studied and most frequently used fundamental physicochemical properties. At present there are several possibilities for its quantitative expression and many of them stems from chromatographic experiments. Numerous attempts have been made to compare different computational methods, chromatographic methods vs. computational approaches, as well as chromatographic methods and direct shake-flask procedure without definite results or these findings are not accepted generally. In the present work numerous chromatographically derived lipophilicity measures in combination with diverse computational methods were ranked and clustered using the novel variable discrimination and ranking approaches based on the sum of ranking differences and the generalized pair correlation method. Available literature logP data measured on HILIC, and classical reversed-phase combining different classes of compounds have been compared with most frequently used multivariate data analysis techniques (principal component and hierarchical cluster analysis) as well as with the conclusions in the original sources. Chromatographic lipophilicity measures obtained under typical reversed-phase conditions outperform the majority of computationally estimated logPs. Oppositely, in the case of HILIC none of the many proposed chromatographic indices overcomes any of the computationally assessed logPs. Only two of them (logkmin and kmin) may be selected as recommended chromatographic lipophilicity measures. Both ranking approaches, sum of ranking differences and generalized pair correlation method, although based on different backgrounds, provides highly similar variable ordering and grouping leading to the same conclusions.

  17. Analysis of carbonyl compounds via headspace solid-phase microextraction with on-fiber derivatization and gas chromatographic-ion trap tandem mass spectrometric determination of their O-(2,3,4,5,6-pentafluorobenzyl)oxime derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Schmarr, Hans-Georg [Dienstleistungszentrum Laendlicher Raum (DLR) Rheinpfalz, Breitenweg 71, D-67435 Neustadt an der Weinstrasse (Germany)], E-mail: hans-georg.schmarr@dlr.rlp.de; Potouridis, Theodoros; Ganss, Sebastian; Sang, Wei; Koepp, Benedikt; Bokuz, Ursula; Fischer, Ulrich [Dienstleistungszentrum Laendlicher Raum (DLR) Rheinpfalz, Breitenweg 71, D-67435 Neustadt an der Weinstrasse (Germany)

    2008-06-09

    An improved method for the analysis of carbonyls is described utilizing a headspace solid-phase microextraction (HS-SPME) step and on-fiber derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) hydrochloride. Thermal desorption of the oxime derivatives formed on the fiber is followed by gas chromatographic separation coupled to an ion trap tandem mass spectrometer (GC-ITMS). Selecting specific fragment ions within the electron ionization (EI{sup +}) mass spectra of these oxime derivatives as precursor ions for MS-MS fragmentation provides a suitable method for the target analysis of individual carbonyl classes, such as alkanals, (E)-2-alkenals, (E,E)-2,4-alkadienals, and others. Retention indices on polar as well as on apolar stationary phases along with EI{sup +} mass spectra patterns are presented for a large set of oxime derivatives, giving valuable information needed for unambiguous assignment of substances in complex sample matrices. The fast sample preparation and derivatization step via HS-SPME can be automated and is applicable to a variety of biological samples and foodstuffs, allowing rapid and sensitive screening analyses of important aldehydic biomarkers and aroma active compounds.

  18. Use of Reciprocal Lattice Layer Spacing in Electron Backscatter Diffraction Pattern Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Eades, J.A.; Michael, J.R.

    1999-05-10

    In the scanning electron microscope (SEM), using electron backscattered diffraction (EBSD), it is possible to measure the spacing of the layers in the reciprocal lattice. These values are of great use in confirming the identification of phases. The technique derives the layer spacing from the HOLZ rings which appear in patterns from many materials. The method adapts results from convergent-beam electron diffraction (CBED) in the transmission electron microscope (TEM). For many materials the measured layer spacing compares well with the calculated layer spacing. A noted exception is for higher atomic number materials. In these cases an extrapolation procedure is described that requires layer spacing measurements at a range of accelerating voltages. This procedure is shown to improves the accuracy of the technique significantly. The application of layer spacing measurements in EBSD is shown to be of use for the analysis of two polytypes of SiC.

  19. Analysis of the cell surface layer ultrastructure of the oral pathogen Tannerella forsythia.

    Science.gov (United States)

    Sekot, Gerhard; Posch, Gerald; Oh, Yoo Jin; Zayni, Sonja; Mayer, Harald F; Pum, Dietmar; Messner, Paul; Hinterdorfer, Peter; Schäffer, Christina

    2012-06-01

    The Gram-negative oral pathogen Tannerella forsythia is decorated with a 2D crystalline surface (S-) layer, with two different S-layer glycoprotein species being present. Prompted by the predicted virulence potential of the S-layer, this study focused on the analysis of the arrangement of the individual S-layer glycoproteins by a combination of microscopic, genetic, and biochemical analyses. The two S-layer genes are transcribed into mRNA and expressed into protein in equal amounts. The S-layer was investigated on intact bacterial cells by transmission electron microscopy, by immune fluorescence microscopy, and by atomic force microscopy. The analyses of wild-type cells revealed a distinct square S-layer lattice with an overall lattice constant of 10.1 ± 0.7 nm. In contrast, a blurred lattice with a lattice constant of 9.0 nm was found on S-layer single-mutant cells. This together with in vitro self-assembly studies using purified (glyco)protein species indicated their increased structural flexibility after self-assembly and/or impaired self-assembly capability. In conjunction with TEM analyses of thin-sectioned cells, this study demonstrates the unusual case that two S-layer glycoproteins are co-assembled into a single S-layer. Additionally, flagella and pilus-like structures were observed on T. forsythia cells, which might impact the pathogenicity of this bacterium.

  20. Analysis of the scattering performance of human retinal tissue layers

    Science.gov (United States)

    Zhu, Dan; Gao, Zhisan; Ye, Haishui; Yuan, Qun

    2017-02-01

    Human retina is different from other ocular tissues, such as cornea, crystalline lens and vitreous because of high scattering performance. As an anisotropic tissue, we cannot neglect its impact on the polarization state of the scattered light. In this paper, Mie scattering and radiative transfer theory are applied to analyze the polarization state of backscattered light from four types of retinal tissues, including neural retina, retinal pigment epithelial (RPE), choroid and sclera. The results show that the most backscattered zones in different depths have almost the same electrical fields of Jones vector, which represents the polarization state of light, whether neural retina layer is under normal incidence or oblique incidence. Very little change occurs in the polarization of backscattered light compared to that of the incident light. Polarization distribution of backward scattered light from neural retina layer doesn't make apparent effects on polarization phase shifting in spectral domain OCT because its thickness is far less than photon mean free path, while other retinal tissues do not meet this rule.

  1. Interferometer and analysis methods for the in vitro characterization of dynamic fluid layers on contact lenses

    Science.gov (United States)

    Primeau, Brian C.; Greivenkamp, John E.

    2012-06-01

    The anterior refracting surface of the eye when wearing a contact lens is the thin fluid layer that forms on the surface of the contact lens. Under normal conditions, this fluid layer is less than 10 μm thick. The fluid layer thickness and topography change over time and are affected by the material properties of the contact lens and may affect vision quality and comfort. An in vitro method of characterizing dynamic fluid layers applied to contact lenses mounted on mechanical substrates has been developed by use of a phase-shifting Twyman-Green interferometer. This interferometer continuously measures light reflected from the surface of the fluid layer, allowing precision analysis of the dynamic fluid layer. Movies showing this fluid layer behavior can be generated. Quantitative analysis beyond typical contact angle or visual inspection methods is provided. Different fluid and contact lens material combinations have been evaluated, and variations in fluid layer properties have been observed. This paper discusses the interferometer design and analysis methods used. Example measurement results of different contact lens are presented.

  2. Elastoplastic numerical analysis of layered soil foundation under the rectangular shallow footing subjected to vertical load

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Finite and infinite coupled element method was used to analyze the strength and deformation in layered soil foundation which was under the rectangular shallow footing subjected to vertical loads. In the numerical analysis, the footing was assumed to be elastic; the soil was assumed to be elastoplastic and the Drucker-Prager constitutive model was applied to describe its mechanic behavior. Corresponding program was employed to compute six kinds of layered soil foundations constituted by different soil layers. The conclusions which are useful in the theory and practice were made according to the analysis of the computation results.

  3. Design and analysis of two-layer anonymous communication system

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-ping; WANG Jian-xin

    2007-01-01

    A new architecture for scalable anonymous communication system(SACS) was proposed. The users were divided into several subgroups managed by different sub-blenders, and all sub-blenders were managed by the main-blender using two layers management scheme. The identity information of members are distributed on different sub-blenders, which makes each member keep much less information and network overload greatly reduce. The anonymity and the overhead of the new scheme were analyzed and compared with that of Crowds, which shows the cost of storage and network overhead for the new scheme largely decreases while the anonymity is little degraded. The experiment results also show that the new system architecture is well scalable. The ratio of management cost of SACS to that of Crowds is about 1:25 while the value of P(I|H1+) only increases by 0.001-0.020, which shows that SACS keeps almost the same anonymity with Crowds.

  4. Modified boundary layer analysis for a mode III crack problem

    Energy Technology Data Exchange (ETDEWEB)

    Beom, Hyeon Gyu; Kim, Yu Hwan; Cho, Chong Du; Kim, Chang Boo [Inha University, Incheon (Korea, Republic of)

    2008-04-15

    A modified boundary layer problem of a semi-infinite crack in an elastic-perfectly plastic material under a Mode III load is analyzed. The analytic solution of elastic fields is derived by using complex function theory. It is found that the size and the shape of the plastic zone near the crack tip depend on the elastic T-stress given on the remote boundary. A method for determining higher order singular solutions of elastic fields is also proposed. In order to determine the higher order singular solutions of the elastic fields, Williams expansion of the solution is used. Higher order terms in the Williams expansion are obtained through simple mathematical manipulation. The coefficients of each term in the Williams expansion are also calculated numerically with the J-based mutual integral

  5. Two multidimensional chromatographic methods for enantiomeric analysis of o,p'-DDT and o,p'-DDD in contaminated soil and air in a malaria area of South Africa.

    Science.gov (United States)

    Naudé, Yvette; Rohwer, Egmont R

    2012-06-12

    In rural parts of South Africa the organochlorine insecticide DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is still used for malaria vector control where traditional dwellings are sprayed on the inside with small quantities of technical DDT. Since o,p'-DDT may show enantioselective oestrogenicity and biodegradability, it is important to analyse enantiomers of o,p'-DDT and its chiral degradation product, o,p'-DDD, for both health and environmental-forensic considerations. Generally, chiral analysis is performed using heart-cut multidimensional gas chromatography (MDGC) and, more recently, comprehensive two-dimensional gas chromatography (GC×GC). We developed an off-line gas chromatographic fraction collection (heart-cut) procedure for the selective capturing of the appropriate isomers from a first apolar column, followed by reinjection and separation on a second chiral column. Only the o,p'-isomers of DDT and DDD fractions from the first dimension complex chromatogram (achiral apolar GC column separation) were selectively collected onto a polydimethylsiloxane (PDMS) multichannel open tubular silicone rubber trap by simply placing the latter device on the flame tip of an inactivated flame ionisation detector (FID). The multichannel trap containing the o,p'-heart-cuts was then thermally desorbed into a GC with time-of-flight mass spectrometry detection (GC-TOFMS) for second dimension enantioselective separation on a chiral column (β-cyclodextrin-based). By selectively capturing only the o,p'-isomers from the complex sample chromatogram, (1)D separation of ultra-trace level enantiomers could be achieved on the second chiral column without matrix interference. Here, we present solventless concentration techniques for extraction of DDT from contaminated soil and air, and report enantiomeric fraction (EF) values of o,p'-DDT and o,p'-DDD obtained by a new multidimensional approach for heart-cut gas chromatographic fraction collection for off-line second dimension

  6. A numerical framework for the mechanical analysis of dual-layer stents in intracranial aneurysm treatment.

    Science.gov (United States)

    Alherz, Ali I; Tanweer, Omar; Flamini, Vittoria

    2016-08-16

    Dual-layer stents and multi-layer stents represent a new paradigm in endovascular interventions. Multi-layer stents match different stent designs in order to offer auxiliary functions. For example, dual-layer stents used in the endovascular treatment of intracranial aneurysms, like the FRED(TM) (MicroVention, CA) stent, combine a densely braided inner metallic mesh with a loosely braided outer mesh. The inner layer is designed to divert blood flow, whereas the outer one ensures microvessels branching out of the main artery remain patent. In this work, the implemented finite element (FE) analysis identifies the key aspects of dual-stent mechanics. In particular, dual-layer stents used in the treatment of intracranial aneurysms require the ability to conform to very narrow passages in their closed configuration, while at the same time they have to provide support and stability once deployed. This study developed a numerical framework for the analysis of dual-layer stents for endovascular intracranial aneurysm treatment. Our results were validated against analytical methods. For the designs considered, we observed that foreshortening was in average 37.5%±2.5%, and that doubling the number of wires in the outer stent increased bending moment by 23%, while halving the number of wires of the inner stent reduced von Mises stress by 2.3%. This framework can be extended to the design optimization of multi-layer stents used in other endovascular treatments.

  7. Optimization of a novel headspace-solid-phase microextraction-gas chromatographic method by means of a Doehlert uniform shell design for the analysis of trace level ethylene oxide residuals in sterilized medical devices.

    Science.gov (United States)

    DiCicco, Michael P; Lang, Bridget; Harper, Thomas I

    2009-06-01

    Medical devices sterilized by ethylene oxide (EtO) retain trace quantities of EtO residuals, which may irritate patients' tissue. Reliably quantifying trace level EtO residuals in small medical devices requires an extremely sensitive analytical method. In this research, a Doehlert uniform shell design was utilized in obtaining a response surface to optimize a novel headspace-solid-phase microextraction-gas chromatographic (HS-SPME-GC) method developed for analyzing trace levels of EtO residuals in sterilized medical devices, by evaluating sterilized, polymer-coated, drug-eluting cardiovascular stents. The effects of four independent experimental variables (HS-SPME desorption time, extraction temperature, GC inlet temperature and extraction time) on GC peak area response of EtO were investigated simultaneously and the most influential experimental variables determined were extraction temperature and GC inlet temperature, with the fitted model showing no evidence of lack-of-fit. The optimized HS-SPME-GC method demonstrated overall good linearity/linear range, accuracy, repeatability, reproducibility, absolute recovery and high sensitivity. This novel method was successfully applied to analysis of trace levels of EtO residuals in sterilized/aerated cardiovascular stents of various lengths and internal diameter, where, upon heating, trace EtO residuals fully volatilized into HS for extraction, thereby nullifying matrix effects. As an alternative, this novel HS-SPME-GC method can offer higher sensitivity compared with conventional headspace analyzer-based sampling.

  8. QUALITY ASSURANCE STUDY OF MARINE LIPID CLASS DETERMINATION USING CHROMAROD/IATROSCAN( REG. TRADEMARK) THIN-LAYER CHROMATOGRAPHY-FLAME IONIZATION DETECTOR

    Science.gov (United States)

    An Iatroscan thin-layer chromatorgraphy-flame ionization detector has been utilized to quantify lipid classes in marine samples. This method was evaluated relative to established quality assurance (QA) procedures used for the gas chromatographic analysis of PCBs. A method for ext...

  9. Nanofluidic Size-Exclusion Chromatograph

    Science.gov (United States)

    Feldman, Sabrina; Svehla, Danielle; Grunthaner, Frank; Feldman, Jason; Shakkottai, P.

    2004-01-01

    Efforts are under way to develop a nanofluidic size-exclusion chromatograph (SEC), which would be a compact, robust, lightweight instrument for separating molecules of interest according to their sizes and measuring their relative abundances in small samples. About as large as a deck of playing cards, the nanofluidic SEC would serve, in effect, as a laboratory on a chip that would perform the functions of a much larger, conventional, bench-top SEC and ancillary equipment, while consuming much less power and much smaller quantities of reagent and sample materials. Its compactness and low power demand would render it attractive for field applications in which, typically, it would be used to identify and quantitate a broad range of polar and nonpolar organic compounds in soil, ice, and water samples. Size-exclusion chromatography is a special case of high-performance liquid chromatography. In a conventional SEC, a sample plug is driven by pressure along a column packed with silica or polymer beads that contain uniform nanopores. The interstices between, and the pores in, the beads collectively constitute a size-exclusion network. Molecules follow different paths through the size-exclusion network, such that characteristic elution times can be related to sizes of molecules: basically, smaller molecules reach the downstream end of the column after the larger ones do because the smaller ones enter minor pores and stay there for a while, whereas the larger ones do not enter the pores. The volume accessible to molecules gradually diminishes as their size increases. All molecules bigger than a pore size elute together. For most substances, the elution times and sizes of molecules can be correlated directly with molecular weights. Hence, by measuring the flux of molecules arriving at the downstream end as a function of time, one can obtain a liquid mass spectrum for the molecules present in a sample over a broad range of molecular weights.

  10. Two-step ion-exchange chromatographic purification combined with reversed-phase chromatography to isolate C-peptide for mass spectrometric analysis.

    Science.gov (United States)

    Kabytaev, Kuanysh; Durairaj, Anita; Shin, Dmitriy; Rohlfing, Curt L; Connolly, Shawn; Little, Randie R; Stoyanov, Alexander V

    2016-02-01

    A liquid chromatography with mass spectrometry on-line platform that includes the orthogonal techniques of ion exchange and reversed phase chromatography is applied for C-peptide analysis. Additional improvement is achieved by the subsequent application of cation- and anion-exchange purification steps that allow for isolating components that have their isoelectric points in a narrow pH range before final reversed-phase mass spectrometry analysis. The utility of this approach for isolating fractions in the desired "pI window" for profiling complex mixtures is discussed.

  11. ANALYSIS OF ELASTIC LAYERS WITH DILATIVE EIGENSTRAINS VARYING THROUGH THE THICKNESS

    Institute of Scientific and Technical Information of China (English)

    何陵辉; 林志华; 刘人怀

    2003-01-01

    Elastic layers with varying dilative eigenstrains through the thickness were concerned. A general procedure was proposed for the analysis of such layers under arbitrary loads. The study is based on the state-space method and an asymptotic expansion technique.When the external loads are uniform, the expansion terminates after some leading terms, and an explicit representation for the mechanical field in a layer is obtained. This representation relies only on the displacement components of the mid-plane, which are governed by a set of two-dimensional differential equations similar to those in the classical plate theory.Consequently, obtaining the solution to the two-dimensional equations immediately gives the three-dimensional responses of the layer. As an illustrative example, a clamped elliptical layer under a uniformly distributed transverse load is analyzed in detail.

  12. Physicochemical, thin layer and gas-liquid chromatographic ...

    African Journals Online (AJOL)

    DELL

    2012-05-22

    May 22, 2012 ... tree considered to be indigenous to the Indo-Pakistan subcontinent and has been .... is given in Table 1. Most common vegetable oils .... Physico-chemical attributes and heavy metals content of mangoes. (Magnifera Indica) ...

  13. Thin layer chromatographic detection of some common antioxidants

    Directory of Open Access Journals (Sweden)

    Komaitis, M. E.

    1991-12-01

    Full Text Available A method is described for the qualitative determination of butylated hydroxyanisole, butylated hidroxytoluene, propyl gallate, octyl gallate and dodecyl gallate in edible fats and oils. The method is based on the development of a specific colour derived from the reaction of the antioxidants with N,N-dimethyl-p-phenylenediamine in the presence of a mild oxidizing agent in alkaline solution. The method gave good results and can be carried out easily with facilities existing in most analytical laboratories.

    Se describe un método para la determinación cualitativa de 3-t-butil-4-hidroxianisol, 2,6-di-t-butil-4-hidroxitolueno, galato de propilo, galato de octilo y galato de dodecilo en aceites y grasas comestibles. El método está basado en el desarrollo de un derivado coloreado específico a partir de la reacción de los antioxidantes con la N,N-dimetil-p-fenilenediamina en presencia de agente oxidante suave en solución alcalina. El método dio buenos resultados y puede llevarse a cabo fácilmente con los medios existentes en la mayoría de los laboratorios analíticos.

  14. Vibration Suppression Analysis for Supporter with Constrained Layer Damping

    Institute of Scientific and Technical Information of China (English)

    杜华军; 邹振祝; 黄文虎

    2004-01-01

    By analyzing the correlation between modal calculations and modal experiments of a typical supporter, an effective finite element analysis( FEA)model of the actual aerospace supporter is created. According to the analysis of constrained viscoelastic damping, the strategies of PVC have been worked out, and the correlation between modal calculations and modal experiments of the supporter has also been computed, and then, an experiment has been designed based on the calculation results. The results of experiments verify that the PVC strategy can effectively suppress vibration.

  15. Application of Finite Layer Method in Pavement Structural Analysis

    Directory of Open Access Journals (Sweden)

    Pengfei Liu

    2017-06-01

    Full Text Available The finite element (FE method has been widely used in predicting the structural responses of asphalt pavements. However, the three-dimensional (3D modeling in general-purpose FE software systems such as ABAQUS requires extensive computations and is relatively time-consuming. To address this issue, a specific computational code EasyFEM was developed based on the finite layer method (FLM for analyzing structural responses of asphalt pavements under a static load. Basically, it is a 3D FE code that requires only a one-dimensional (1D mesh by incorporating analytical methods and using Fourier series in the other two dimensions, which can significantly reduce the computational time and required resources due to the easy implementation of parallel computing technology. Moreover, a newly-developed Element Energy Projection (EEP method for super-convergent calculations was implemented in EasyFEM to improve the accuracy of solutions for strains and stresses over the whole pavement model. The accuracy of the program is verified by comparing it with results from BISAR and ABAQUS for a typical asphalt pavement structure. The results show that the predicted responses from ABAQUS and EasyFEM are in good agreement with each other. The EasyFEM with the EEP post-processing technique converges faster compared with the results derived from ordinary EasyFEM applications, which proves that the EEP technique can improve the accuracy of strains and stresses from EasyFEM. In summary, the EasyFEM has a potential to provide a flexible and robust platform for the numerical simulation of asphalt pavements and can easily be post-processed with the EEP technique to enhance its advantages.

  16. Ring-element analysis of layered orthotropic bodies

    DEFF Research Database (Denmark)

    Jørgensen, O.

    1993-01-01

    to be determined in the finite element analysis. The element chosen is an eight node isoparametric element of the serendipity family. The Fourier series show very high rate of convergence for the problems solved. The investigation shows that the computational work is remarkably reduced in relation...

  17. Development and validation of an improved reversed-phase liquid chromatographic method combined with pulsed electrochemical detection for the analysis of netilmicin.

    Science.gov (United States)

    Manyanga, Vicky; Hoogmartens, Jos; Adams, Erwin

    2010-07-01

    Netilmicin is one of the aminoglycoside antibiotics that lacks a strong UV absorbing chromophore. However, the application of pulsed electrochemical detection has been used successfully for the direct analysis of aminoglycoside antibiotics. This study describes an improved LC method combined with pulsed electrochemical detection for the analysis of netilmicin. Using a Zorbax SB C-18 column (250 mm x 4.6 mm id, 5 microm), isocratic elution was carried out with a mobile phase containing sodium sulfate (20 g/L), sodium octanesulfonate (0.3 g/L), THF (20 mL/L), and 0.2 M phosphate buffer pH 3.0 (50.0 mL/L). The robustness of the method was examined by means of an experimental design. The method proved to be sensitive, repeatable, linear, and robust. The method has also been used to analyze some commercial netilmicin samples.

  18. Application of acetone acetals as water scavengers and derivatization agents prior to the gas chromatographic analysis of polar residual solvents in aqueous samples.

    Science.gov (United States)

    van Boxtel, Niels; Wolfs, Kris; Van Schepdael, Ann; Adams, Erwin

    2015-12-18

    The sensitivity of gas chromatography (GC) combined with the full evaporation technique (FET) for the analysis of aqueous samples is limited due to the maximum tolerable sample volume in a headspace vial. Using an acetone acetal as water scavenger prior to FET-GC analysis proved to be a useful and versatile tool for the analysis of high boiling analytes in aqueous samples. 2,2-Dimethoxypropane (DMP) was used in this case resulting in methanol and acetone as reaction products with water. These solvents are relatively volatile and were easily removed by evaporation enabling sample enrichment leading to 10-fold improvement in sensitivity compared to the standard 10μL FET sample volumes for a selection of typical high boiling polar residual solvents in water. This could be improved even further if more sample is used. The method was applied for the determination of residual NMP in an aqueous solution of a cefotaxime analogue and proved to be considerably better than conventional static headspace (sHS) and the standard FET approach. The methodology was also applied to determine trace amounts of ethylene glycol (EG) in aqueous samples like contact lens fluids, where scavenging of the water would avoid laborious extraction prior to derivatization. During this experiment it was revealed that DMP reacts quantitatively with EG to form 2,2-dimethyl-1,3-dioxolane (2,2-DD) under the proposed reaction conditions. The relatively high volatility (bp 93°C) of 2,2-DD makes it possible to perform analysis of EG using the sHS methodology making additional derivatization reactions superfluous.

  19. Pheromone synthesis. Part 245: Synthesis and chromatographic analysis of the four stereoisomers of 4,8-dimethyldecanal, the male aggregation pheromone of the red flour beetle, Tribolium castaneum

    Science.gov (United States)

    All four stereoisomers of 4,8-dimethyldecanal (1) were synthesized from the enantiomers of 2-methyl-1-butanol and citronellal. Enantioselective GC analysis enabled separation of (4R,8R)-1 and (4R,8S)-1 from a mixture of (4S,8R)-1 and (4S,8S)-1, when octakis- (2,3-di-O-methoxymethyl-6-O-t-butyldimet...

  20. The Analysis and Construction of Perfectly Matched Layers for the Linearized Euler Equations

    Science.gov (United States)

    Hesthaven, J. S.

    1997-01-01

    We present a detailed analysis of a recently proposed perfectly matched layer (PML) method for the absorption of acoustic waves. The split set of equations is shown to be only weakly well-posed, and ill-posed under small low order perturbations. This analysis provides the explanation for the stability problems associated with the split field formulation and illustrates why applying a filter has a stabilizing effect. Utilizing recent results obtained within the context of electromagnetics, we develop strongly well-posed absorbing layers for the linearized Euler equations. The schemes are shown to be perfectly absorbing independent of frequency and angle of incidence of the wave in the case of a non-convecting mean flow. In the general case of a convecting mean flow, a number of techniques is combined to obtain a absorbing layers exhibiting PML-like behavior. The efficacy of the proposed absorbing layers is illustrated though computation of benchmark problems in aero-acoustics.

  1. Finite layer and triangular prism element method to subsidence prediction and stress analysis in underground mining

    Institute of Scientific and Technical Information of China (English)

    LIU Li-min(刘立民); LIU Han-long(刘汉龙); LIAN Chuan-jie(连传杰)

    2003-01-01

    The application of the finite layer & triangular prism element method to the 3D ground subsidence and stress analysis caused by mining is presented. The layer elements and the triangular prism elements have been alternatively used in the numerical simulation system, the displacement pattern, strain matrix, elastic matrix, stiffness matrix, load matrix and the stress matrix of the layer element and triangular prism element have been presented. By means of the Fortran90 programming language, a numerical simulation system based on finite layer & triangular prism element have been built up, and this system is suitable for subsidence prediction and stress analysis of all mining condition and mining methods. Comparing with the infinite element method, this approach dramatically reduces the size of the set of equations that need to be solved, and greatly reduces the amount of data preparation required. It not only saves the internal storage, and the computation time, but also decreases the cost.

  2. Comprehensive automation of the solid phase extraction gas chromatographic mass spectrometric analysis (SPE-GC/MS) of opioids, cocaine, and metabolites from serum and other matrices.

    Science.gov (United States)

    Lerch, Oliver; Temme, Oliver; Daldrup, Thomas

    2014-07-01

    The analysis of opioids, cocaine, and metabolites from blood serum is a routine task in forensic laboratories. Commonly, the employed methods include many manual or partly automated steps like protein precipitation, dilution, solid phase extraction, evaporation, and derivatization preceding a gas chromatography (GC)/mass spectrometry (MS) or liquid chromatography (LC)/MS analysis. In this study, a comprehensively automated method was developed from a validated, partly automated routine method. This was possible by replicating method parameters on the automated system. Only marginal optimization of parameters was necessary. The automation relying on an x-y-z robot after manual protein precipitation includes the solid phase extraction, evaporation of the eluate, derivatization (silylation with N-methyl-N-trimethylsilyltrifluoroacetamide, MSTFA), and injection into a GC/MS. A quantitative analysis of almost 170 authentic serum samples and more than 50 authentic samples of other matrices like urine, different tissues, and heart blood on cocaine, benzoylecgonine, methadone, morphine, codeine, 6-monoacetylmorphine, dihydrocodeine, and 7-aminoflunitrazepam was conducted with both methods proving that the analytical results are equivalent even near the limits of quantification (low ng/ml range). To our best knowledge, this application is the first one reported in the literature employing this sample preparation system.

  3. Analysis and combined optimization of the cladding layer in outcoupling-improved top emitting OLEDs

    Institute of Scientific and Technical Information of China (English)

    Ligong Yang(杨立功); Peng Wu(吴鹏); Biqin Huang(黄弼勤); Peifu Gu(顾培夫)

    2004-01-01

    Within the associated framework of metal-dielectric films optics and the dual-metal-mirror microcavity structure, the effect of a cladding dielectric layer on the light outcoupling efficiency of the top emitting orgainic light-emitting devices (OLEDs) is analyzed. A combined evaluation followed by detailed design and optimization is proposed and described in detail. The analysis shows that this cladding layer affects the device's outcoupling efficiency with three different extents as the thickness of the metal layer in the multilayer cathode varying. The simulation results give a reasonable agreement with former experiment results.

  4. Analysis and combined optimization of the cladding layer in outcoupling-improved top emitting OLEDs

    Institute of Scientific and Technical Information of China (English)

    杨立功; 吴鹏; 黄弼勤; 顾培夫

    2004-01-01

    Within the associated framework of metal-dielectric films optics and the dual-metal-mirror mnicrocavity structure, the effect of a cladding dielectric layer on the light outcoupling efficiency of the top emitting orgainic light-emitting devices (OLEDs) is analyzed. A combined evaluation followed by detailed design and optimization is proposed and described in detail. The analysis shows that this cladding layer affects the device's outcoupling efficiency with three different extents as the thickness of the metal layer in the multilayer cathode varying. The simulation results give a reasonable agreement with former experiment results.

  5. Decomposition Methods For a Piv Data Analysis with Application to a Boundary Layer Separation Dynamics

    Directory of Open Access Journals (Sweden)

    Václav URUBA

    2010-12-01

    Full Text Available Separation of the turbulent boundary layer (BL on a flat plate under adverse pressure gradient was studied experimentally using Time-Resolved PIV technique. The results of spatio-temporal analysis of flow-field in the separation zone are presented. For this purpose, the POD (Proper Orthogonal Decomposition and its extension BOD (Bi-Orthogonal Decomposition techniques are applied as well as dynamical approach based on POPs (Principal Oscillation Patterns method. The study contributes to understanding physical mechanisms of a boundary layer separation process. The acquired information could be used to improve strategies of a boundary layer separation control.

  6. Liquid chromatographic assay for dicloxacillin in plasma.

    Science.gov (United States)

    Alderete, Oscar; González-Esquivel, Dinora F; Del Rivero, L Misael; Castro Torres, Nelly

    2004-06-15

    A simple high-performance liquid chromatographic method for the determination of dicloxacillin in plasma has been developed. The method only requires 0.5 ml of plasma, phosphate buffer solution (pH = 4.7), acidification with 0.5N hydrochloride acid and liquid extraction with dichloromethane. Posterior evaporation of organic under nitrogen steam and redissolution in mobile phase is carried out. The analysis was performed on a Spherisorb C18 (5 microm) column, using methanol -0.05 M phosphate buffer, pH = 4.7 (75:25; v/v) as mobile phase, with ultraviolet detection at 220 nm. Results showed that the assay is sensitive: 0.5 microg/ml. The response is linear in the range of 0.5 - 10 microg/ml. Maximum inter-day coefficient of variation was 12.4%. Mean extraction recovery obtained was 96.95%. Stability studies showed that the loss was not higher than 10%, samples are stable at room temperature for 6 h, at -20 Celsius for 2 months, processed samples were stable at least for 24 h and also after two freeze-thaw cycles. The method has been used to perform pharmacokinetic and bioequivalence studies in humans.

  7. Analysis of Components in Refinery Gases by Gas Chromatograph -External Standard Normalization%用气相色谱校正归一法分析炼厂气组成

    Institute of Scientific and Technical Information of China (English)

    魏然波; 李冬; 李保; 周晓哲

    2009-01-01

    建立了用HP7890A系列气相色谱仪分析炼厂气的方法,本方法操作简单,一次进样测定炼厂气组成,分析时间在7 min以内.炼厂气的分析由三个通道完成,FID A通道用于分析C_1~C_4和C_5~+烃类,TCD B通道用于分析永久性气体,包括CO_2、H_2S、O_2、N_2和CO,TCD C通道单独用于分析氢气.数据利用安捷伦工作站采集和输出,采用外标面积归一化法进行定量计算.结果表明,该方法准确、快速、简便,适用于炼厂气分析.%A method is established for analyzing refinery gases by HP7890A series gas chromatograph. The operation of this method was simple, all components of refinery gases can determined by injecting sample only once within 7 minutes. The refinery gases were analyzed by three channels. The FID A channel is used to analyze the hydrocarbon components from C_1~C_4 and C_5~+, TCD B channel is used to analyze inert gases, including CO_2, H_2S, O_2, N_2, CO, and TCD C channel is only used to analyze hydrogen. The chemstation of HP7890A can collect and output analysis data. External standard-area normalization was used in quantitative calculation. The result shows this method has the advantages of accuracy, rapidity and simplicity, being suitable for refinery gases analysis.

  8. Digitally Enhanced Thin-Layer Chromatography: An Inexpensive, New Technique for Qualitative and Quantitative Analysis

    Science.gov (United States)

    Hess, Amber Victoria Irish

    2007-01-01

    A study conducted shows that if digital photography is combined with regular thin-layer chromatography (TLC), it could perform highly improved qualitative analysis as well as make accurate quantitative analysis possible for a much lower cost than commercial equipment. The findings suggest that digitally enhanced TLC (DE-TLC) is low-cost and easy…

  9. Digitally Enhanced Thin-Layer Chromatography: An Inexpensive, New Technique for Qualitative and Quantitative Analysis

    Science.gov (United States)

    Hess, Amber Victoria Irish

    2007-01-01

    A study conducted shows that if digital photography is combined with regular thin-layer chromatography (TLC), it could perform highly improved qualitative analysis as well as make accurate quantitative analysis possible for a much lower cost than commercial equipment. The findings suggest that digitally enhanced TLC (DE-TLC) is low-cost and easy…

  10. Analysis of WiMAX Physical Layer Using Spatial Multiplexing

    CERN Document Server

    Sanghoi, Pavani

    2012-01-01

    Broadband Wireless Access (BWA) has emerged as a promising solution for providing last mile internet access technology to provide high speed internet access to the users in the residential as well as in the small and medium sized enterprise sectors. IEEE 802.16e is one of the most promising and attractive candidate among the emerging technologies for broadband wireless access. The emergence of WiMAX protocol has attracted various interests from almost all the fields of wireless communications. MIMO systems which are created according to the IEEE 802.16-2005 standard (WiMAX) under different fading channels can be implemented to get the benefits of both the MIMO and WiMAX technologies. In this paper analysis of higher level of modulations (i.e. M-PSK and M-QAM for different values of M) with different code rates and on WiMAX-MIMO system is presented for Rayleigh channel by focusing on spatial multiplexing MIMO technique. Signal-to Noise Ratio (SNR) vs Bit Error Rate (BER) analysis has been done.

  11. Interlaboratory comparison of two AOAC liquid chromatographic fluorescence detection methods for paralytic shellfish toxin analysis through characterization of an oyster reference material.

    Science.gov (United States)

    Turner, Andrew D; Lewis, Adam M; Rourke, Wade A; Higman, Wendy A

    2014-01-01

    An interlaboratory ring trial was designed and conducted by the Centre for Environment, Fisheries, and Aquaculture Science to investigate a range of issues affecting the analysis of a candidate Pacific oyster paralytic shellfish toxin reference material. A total of 21 laboratories participated in the study and supplied results using one or more of three instrumental methods, specifically precolumn oxidation (Pre-COX) LC with fluorescence detection (FLD; AOAC Official Method 2005.06), postcolumn oxidation (PCOX) LC-FLD (AOAC Official Method 2011.02), and hydrophilic interaction LC/MS/MS. Each participant analyzed nine replicate samples of the oyster tissue in three separate batches of three samples over a period of time longer than 1 week. Results were reported in a standardized format, reporting both individual toxin concentrations and total sample toxicity. Data were assessed to determine the equivalency of the two AOAC LC methods and the LC/MS/MS method as well as an assessment of intrabatch and interbatch repeatability and interlaboratory reproducibility of each method. Differences among the results reported using the three methods were shown to be statistically significant, although visual comparisons showed an overlap between results generated by the majority of tests, the exception being the Pre-COX quantitation of N-hydroxylated toxins in post ion-exchange fractions. Intralaboratory repeatability and interlaboratory reproducibility were acceptable for most of the results, with the exception of results generated from fractions. The results provided good evidence for the acceptable performance of the PCOX method for the quantitation of C toxins. Overall the study showed the usefulness of interlaboratory analysis for the characterization of paralytic shellfish poisoning matrix reference materials, highlighting some issues that may need to be addressed with further method assessment at individual participant laboratories.

  12. Analysis of phenolics in wine by high performance thin-layer chromatography with gradient elution and high resolution plate imaging.

    Science.gov (United States)

    Agatonovic-Kustrin, Snezana; Hettiarachchi, Chandima G; Morton, David W; Razic, Slavica

    2015-01-01

    Health benefits of wine, especially with red wine, have been linked to the presence of a wide range of phenolic antioxidants. Thus, the aim of this study was to develop a simple, high performance thin layer chromatographic (HPTLC) method combined with high resolution digital plate images to visually compare multiple wine samples simultaneously on a single chromatographic plate and to quantify levels of gallic acid, caffeic acid, resveratrol and rutin, as representatives of the four different classes of phenolics found in wines. We also wanted to investigate the contribution of the investigated phenolic compounds to the total polyphenolic content (TPC) and total antioxidant capacity (TAC) of the wine samples. The average concentrations of caffeic acid, gallic acid, resveratrol, and rutin in the red wines were 2.15, 30.17, 0.59 and 2.47 mg/L respectively with their concentration below limit of quantification in the white wine samples. The highest concentration of resveratrol and rutin is found in the Cabernet and Shiraz wine samples. The amounts of gallic acid are correlated with TPC (r=0.58). Italian wines have the highest correlation between TPC and TAC (r=0.99) although they do not contain detectable amounts of resveratrol, they contain significant amount of rutin. Therefore, antioxidant properties might be associated with the presence of flavanols in these wines.

  13. Mass fragmentation study of the trimethylsilyl derivatives of arctiin, matairesinoside, arctigenin, phylligenin, matairesinol, pinoresinol and methylarctigenin: their gas and liquid chromatographic analysis in plant extracts.

    Science.gov (United States)

    Boldizsár, I; Füzfai, Zs; Tóth, F; Sedlák, E; Borsodi, L; Molnár-Perl, I

    2010-03-01

    The mass fragmentation patterns and the characteristic behavior of the trimethylsilyl (TMS) derivatives of the dibenzylbutyrolactone-type (arctiin, arctigenin, methylarctigenin, matairesinoside, matairesinol) and those of the diphenylperhydrofurotetrahydrofurane-type (phylligenin, pinoresinol) lignans, obtained by gas chromatography-mass spectrometry (GC-MS), were presented. It was shown that upon acidic hydrolysis the dibenzylbutyrolactone-type lignans are stable while the diphenylperhydrofurotetrahydrofurane-type ones decompose. As a novelty to the field we confirmed that the fragment species of the derivatized lignan glycosides, in the presence of excess hexamethyldisilazane, leaded to their in situ derivatization. Quantification of the selective fragment ions of the TMS derivatives by GC-MS, in respect of the ions found one by one, and concerning the selective fragment ions {SFI(s)} in total, provided acceptable reproducibilities, suitable for quantitation purposes: varying between 1.20% and 6.6% relative standard deviation percentages (RSD%). For characterization of the behavior of various type of lignans, analyses were performed with the untreated and with the trifluoroacetic acid hydrolyzed plant extracts, from the same sample, in parallel, both by GC-MS and by high performance liquid chromatography-mass spectrometry, working in the positive electron ionization mode (HPLC-ESPI-MS). The analysis of lignans in fruit and leaf extracts (obtained from the Arctium, Centaurea and Forsythia plants) was confirmed both by GC-MS and by HPLC-ESPI-MS. Our multicomponent system (including the identification and quantification of sugars, sugar alcohols, and several members of various homologous series of acids, anthraquinones and flavonoids) has been extended to the analysis of lignan glycosides and to the free lignans. Reproducibilities in the quantitation of lignans in plant matrices, as averages on GC and HPLC basis, varied between 0.9% and 11% (RSD). The distribution

  14. A rapid method for the chromatographic analysis of volatile organic compounds in exhaled breath of tobacco cigarette and electronic cigarette smokers.

    Science.gov (United States)

    Marco, Esther; Grimalt, Joan O

    2015-09-04

    A method for the rapid analysis of volatile organic compounds (VOCs) in smoke from tobacco and electronic cigarettes and in exhaled breath of users of these smoking systems has been developed. Both disposable and rechargeable e-cigarettes were considered. Smoke or breath were collected in Bio-VOCs. VOCs were then desorbed in Tenax cartridges which were subsequently analyzed by thermal desorption coupled to gas chromatography-mass spectrometry. The method provides consistent results when comparing the VOC compositions from cigarette smoke and the equivalent exhaled breath of the smokers. The differences in composition of these two sample types are useful to ascertain which compounds are retained in the respiratory system after tobacco cigarette or e-cigarette smoking. Strong differences were observed in the VOC composition of tobacco cigarette smoke and exhaled breath when comparing with those of e-cigarette smoking. The former involved transfers of a much larger burden of organic compounds into smokers, including benzene, toluene, naphthalene and other pollutants of general concern. e-Cigarettes led to strong absorptions of propylene glycol and glycerin in the users of these systems. Tobacco cigarettes were also those showing highest concentration differences between nicotine concentrations in smoke and exhaled breath. The results from disposable e-cigarettes were very similar to those from rechargeable e-cigarettes. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Liquid Anion Exchange Chromatographic Extraction and Separation of Platinum(IV with n-Octylaniline as a Metallurgical Reagent: Analysis of Real Samples

    Directory of Open Access Journals (Sweden)

    Ashwini P. Gaikwad

    2013-01-01

    Full Text Available A simple and selective method was developed for the determination of platinum(IV with n-octylaniline in toluene. In present study, the use of n-octylaniline in toluene for the extraction of platinum(IV from ascorbate media was carried out. The effect of various parameters, such as pH, equilibrium time, extractant concentration, and organic solvent on the extraction has been discussed. The back extraction of platinum(IV has been performed. On the basis of slope analysis, the composition of the extracted species was determined as [RR′NH2+ Pt(Succinate2−](org. The interfering effects of various cations and anions were also studied, and the selectivity of the method is enhanced by using suitable masking agents. The proposed method is rapid, reproducible and successfully applied for the determination of platinum(IV in binary and synthetic mixtures. The separation of pt(IV from other associated metals has been studied. Comparison of the results with those obtained using an atomic absorption spectrophotometer also tested the validity of the method.

  16. Chromatographic and Spectral Analysis of Two Main Extractable Compounds Present in Aqueous Extracts of Laminated Aluminum Foil Used for Protecting LDPE-Filled Drug Vials

    Directory of Open Access Journals (Sweden)

    Samuel O. Akapo

    2009-01-01

    Full Text Available Laminated aluminum foils are increasingly being used to protect drug products packaged in semipermeable containers (e.g., low-density polyethylene (LDPE from degradation and/or evaporation. The direct contact of such materials with primary packaging containers may potentially lead to adulteration of the drug product by extractable or leachable compounds present in the closure system. In this paper, we described a simple and reliable HPLC method for analysis of an aqueous extract of laminated aluminum foil overwrap used for packaging LDPE vials filled with aqueous pharmaceutical formulations. By means of combined HPLC-UV, GC/MS, LC/MS/MS, and NMR spectroscopy, the two major compounds detected in the aqueous extracts of the representative commercial overwraps were identified as cyclic oligomers with molecular weights of 452 and 472 and are possibly formed from poly-condensation of the adhesive components, namely, isophthalic acid, adipic acid, and diethylene glycol. Lower molecular weight compounds that might be associated with the “building blocks” of these compounds were not detected in the aqueous extracts.

  17. Automated multi-plug filtration cleanup for liquid chromatographic-tandem mass spectrometric pesticide multi-residue analysis in representative crop commodities.

    Science.gov (United States)

    Qin, Yuhong; Zhang, Jingru; Zhang, Yuan; Li, Fangbing; Han, Yongtao; Zou, Nan; Xu, Haowei; Qian, Meiyuan; Pan, Canping

    2016-09-01

    An automated multi-plug filtration cleanup (m-PFC) method on modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) extracts was developed. The automatic device was aimed to reduce labor-consuming manual operation workload in the cleanup steps. It could control the volume and the speed of pulling and pushing cycles accurately. In this work, m-PFC was based on multi-walled carbon nanotubes (MWCNTs) mixed with other sorbents and anhydrous magnesium sulfate (MgSO4) in a packed tip for analysis of pesticide multi-residues in crop commodities followed by liquid chromatography with tandem mass spectrometric (LC-MS/MS) detection. It was validated by analyzing 25 pesticides in six representative matrices spiked at two concentration levels of 10 and 100μg/kg. Salts, sorbents, m-PFC procedure, automated pulling and pushing volume, automated pulling speed, and pushing speed for each matrix were optimized. After optimization, two general automated m-PFC methods were introduced to relatively simple (apple, citrus fruit, peanut) and relatively complex (spinach, leek, green tea) matrices. Spike recoveries were within 83 and 108% and 1-14% RSD for most analytes in the tested matrices. Matrix-matched calibrations were performed with the coefficients of determination >0.997 between concentration levels of 10 and 1000μg/kg. The developed method was successfully applied to the determination of pesticide residues in market samples.

  18. Automated resolution of chromatographic signals by independent component analysis-orthogonal signal deconvolution in comprehensive gas chromatography/mass spectrometry-based metabolomics.

    Science.gov (United States)

    Domingo-Almenara, Xavier; Perera, Alexandre; Ramírez, Noelia; Brezmes, Jesus

    2016-07-01

    Comprehensive gas chromatography-mass spectrometry (GC×GC-MS) provides a different perspective in metabolomics profiling of samples. However, algorithms for GC×GC-MS data processing are needed in order to automatically process the data and extract the purest information about the compounds appearing in complex biological samples. This study shows the capability of independent component analysis-orthogonal signal deconvolution (ICA-OSD), an algorithm based on blind source separation and distributed in an R package called osd, to extract the spectra of the compounds appearing in GC×GC-MS chromatograms in an automated manner. We studied the performance of ICA-OSD by the quantification of 38 metabolites through a set of 20 Jurkat cell samples analyzed by GC×GC-MS. The quantification by ICA-OSD was compared with a supervised quantification by selective ions, and most of the R(2) coefficients of determination were in good agreement (R(2)>0.90) while up to 24 cases exhibited an excellent linear relation (R(2)>0.95). We concluded that ICA-OSD can be used to resolve co-eluted compounds in GC×GC-MS.

  19. Comparison of solid-phase microextraction and dynamic headspace methods for the gas chromatographic-mass spectrometric analysis of light-induced lipid oxidation products in milk.

    Science.gov (United States)

    Marsili, R T

    1999-01-01

    A sensitive, rapid procedure for testing lipid oxidation products in milk is developed using solid-phase microextraction (SPME) and gas chromatography-mass spectrometry. SPME is as sensitive as dynamic headspace (DH) analysis for measuring the pentanal and hexanal produced in milk after exposure to light. Furthermore, compared with DH, SPME is less expensive and demonstrates better precision and accuracy. In addition, SPME does not exhibit carryover or septa artifact peaks. The linearity of calibration curves (based on the method of additions technique with an internal standard) is consistently better for SPME than for DH. Furthermore, replicate analyses of pentanal and hexanal spiked in skim milk and 2% milk at 2 ng/mL demonstrate significantly lower coefficients of variation using SPME. To further test the practicality of SPME for measuring light-induced chemical changes in milk, 2% milk and skim milk samples are exposed to fluorescent light (200 foot-candles) for 0, 3, 6, 9, 12, 17, 24, and 48 h and analyzed by SPME and DH. Pentanal and hexanal in all samples are measured by SPME and DH. Correlation coefficients of resulting plots indicate that SPME is more accurate than DH in measuring the quantity of lipid oxidation products in milk.

  20. OPTIMISATION OF RESIDENTIAL ROOF INSULATION LAYER THICKNESS BASED ON ECONOMIC ANALYSIS BY GREY RELATION METHOD

    Directory of Open Access Journals (Sweden)

    D. PRAKASH

    2015-12-01

    Full Text Available This study is focussed on the optimisation of residential building roof insulation layers that includes weathering tile, wood wool and phase change material through grey relation analysis and numerical simulation techniques. The optimum thickness of insulation layers is determined for the quality objective of minimization of insulation material cost and energy consumption cost by air conditioning system over a life time of 10 years. For optimisation of roof insulation layer, the insulation layers are varied to five levels with reference to the height of concrete (HC layer and various combination of roof layers are obtained from Taguchi’s L25 orthogonal array. The 25 combination of roof structures are analysed by Numerical simulation technique to determine yearly heating transmission load and in turn used to calculate the cost of energy consumption for cooling a period of 10 years. As a result, the optimum thickness value of roof insulation layer - weathering tile, wood wool and phase change material are predicted as 0.33*HC, 0.33*HC and 0.066*HC respectively and this optimum value will have the cost of insulation and yearly electricity cost of cooling for 10 years as 92 $/m2 and 12.45$/m2 respectively.

  1. High-separation performance of chromatographic capillaries coated with MOF-5 by the controlled SBU approach.

    Science.gov (United States)

    Münch, Alexander S; Seidel, Jürgen; Obst, Anja; Weber, Edwin; Mertens, Florian O R L

    2011-09-19

    Recently developed MOF surface-coating techniques, the controlled SBU approach (CSA) for the generation of MOF-5, and the use of self-assembled monolayers have been combined to generate a wall-bonded, crosslinked stationary phase for gas chromatographic capillary columns displaying excellent performance in the separation of natural gas components. The chromatographic performance of this new type of column has been compared to the state-of-the-art solution for this separation problem, namely a coated silica column of the porous layer open tubular (PLOT) type. Chromatographic parameters such as separation, resolution, and tailing factors, as well as plate numbers and heights in the case of isothermal operation, have been determined. Kinetic and thermodynamic parameters characterizing the analyte-stationary phase interaction have been determined for various C1-C4 analytes.

  2. Model and numerical analysis of 3D corrosion layer of reinforced concrete structure

    Institute of Scientific and Technical Information of China (English)

    李永和; 葛修润

    2003-01-01

    Under the assumption that the corrosion at the end of steel bolt or steel bar is shaped like the contour line of ellipsoid, a mathematic model and formulas of calculating the thickness of corrosion layer at arbitrary point are presented in this paper. Then regarding the arbitrary points of 3D corrosion layer as patch element model of fictitious displacement discontinuity, we propose the basic solution of 3D problem of the patch element acting on discontinuous displacement. With three basic assumptions of the corrosion layer, we set up the 3D numerical discreted model, and derive the stress boundary equation for fictitious corrosion layer of 3D numerical analysis. We also make the numerical stimulating calculation of the shotcrete structure at some lane using 3D finite element method. The results show that this method is effective and reasonable.

  3. Stress Analysis of a Three-Layer Metal Composite System of Bearing Assemblies During Grinding

    Science.gov (United States)

    Pashnyov, V. A.; Pimenov, D. Yu.

    2015-03-01

    A mathematical model of the stress state of a three-layer metal composite system caused by cutting forces during grinding the working layer of the system is elaborated. The implementation of the model by using the finite-element method made it possible to assess the effect of structure of the system, the deformation properties of layer materials, and grinding conditions on the distribution and level of normal and tangential stresses in layers, which determine the load-carrying capacity of the system. The results of an analysis of stress fields can serve as a basis for determining the grinding conditions ensuring retention of the load-carrying capacity of the metal composite system.

  4. 续断的色谱指纹及LC-ESI-MS分析%Chromatographic fingerprint of Dipsacus asper and analysis by HPLC-MS

    Institute of Scientific and Technical Information of China (English)

    韦英杰; 贾晓斌; 樊宏伟; 彭蕴茹; 詹雯

    2011-01-01

    目的:建立中药续断高效液相指纹图谱,分析色谱峰的化合物类型和质谱特征,提高续断的质量控制水平.方法:采用高效液相色谱-二极管阵列检测器(HPLC-DAD),Zorbax Extend Cl8(4.6 mm×150 mm,5 μm)色谱柱,乙腈-0.1%磷酸水梯度洗脱,以川续断皂苷VI为参照物,建立续断色谱指纹.通过二极管阵列检测分析色谱指纹峰的化合物类型,采用液相色谱与电喷雾质谱联用技术首次分析了续断化学成分的质谱特征.结果:确定24批续断药材的17个共有峰,该指纹图谱具有良好的精密度、稳定性和重复性,成功用于24批续断药材的质量评价.二极管阵列检测区分了续断皂苷和非皂苷类化合物的指纹峰,液相色谱与质谱联用技术鉴定了30多个化合物的相对分子质量,通过与对照品或文献对照对其中10个特征成分进行了推测、确认.结论:采用高效液相色谱与质谱联用技术对续断指纹图谱中的特征峰进行结构确认,结束了续断色谱指纹盲分析的现状,可使其色谱指纹图谱的特征性更强,能更有效、全面的控制续断药材质量.%A high performance liquid chromatography (HPLC) method was developed for fingerprint of Dipsacus asper. Analysis were carried out on a Zorbax C-18 column by gradient elution using 0. 1% phosphoric acid and acetonitrile as the mobile phases.The column was maintained at 25 ℃, the flow rate was 1 mL · min-1 , and the detection wavelength was set at 205 nm. Asperosaponin VI was selected as reference compound, Seventeen common peaks were selected, and the fingerprint with good precision, stability and repeatability was successfully used to evaluate quality of 24 batches of crude extracts of D. asper. Chemical characteristics of D. asper was analyzed by DAD detection and HPLC-MS techniques with an ESI source. The quasi-molecular ions of compounds in both negative and positive modes were observed for molecule mass information of 33

  5. Analysis and Treatment of Abnormal Chromatographic Result Fault in 220kV Main Transformer%一台220kV主变色谱异常故障的分析及处理

    Institute of Scientific and Technical Information of China (English)

    孔祥凤; 李进

    2012-01-01

    The abnormal chromatographic result in 220kV main transformer is analyzed. The fault position is diagnosed based on electric test results.%对220kV主变色谱异常结果进行了分析,结合电气试验对故障的位置进行了判断。

  6. 变压器油色谱分析技术在设备状态检修中的应用%Application of Transformer Oil Chromatographic Analysis Technology to Equipment Condition Maintenace

    Institute of Scientific and Technical Information of China (English)

    粱艳丽; 曹阳

    2011-01-01

    Based on examples, the application of transformer oil chromatographic technology to eqaipment maintenance is analyzed.%通过故障实例,分析了变压器油色谱技术在设备状态检修中的应用。

  7. Enhanced Multi-Layer Fatigue-Analysis Approach for Unbonded Flexible Risers

    Institute of Scientific and Technical Information of China (English)

    杨和振; 姜豪; 杨启

    2014-01-01

    This paper proposes an enhanced approach for evaluating the fatigue life of each metallic layer of unbonded flexible risers. Owing to the complex structure of unbonded flexible risers and the nonlinearity of the system, particularly in the critical touchdown zone, the traditional method is insufficient for accurately evaluating the fatigue life of these risers. The main challenge lies in the transposition from global to local analyses, which is a key stage for the fatigue analysis of flexible pipes owing to their complex structure. The new enhanced approach derives a multi-layer stress-decomposition method to meet this challenge. In this study, a numerical model validated experimentally is used to demonstrate the accuracy of the stress-decomposition method. And a numerical case is studied to validate the proposed approach. The results demonstrate that the multi-layer stress-decomposition method is accurate, and the fatigue lives of the metallic layers predicted by the enhanced multi-layer analysis approach are rational. The proposed fatigue-analysis approach provides a practical and reasonable method for predicting fatigue life in the design of unbonded flexible risers.

  8. Chromatographic Separation of Glucose and Fructose

    Science.gov (United States)

    Kuptsevich, Yu E.; Larionov, Oleg G.; Stal'naya, I. D.; Nakhapetyan, L. A.; Pronin, A. Ya

    1987-03-01

    The structures, mutarotation, and the physicochemical properties of glucose and fructose as well as methods for their separation are examined. Their chromatographic separation on cation exchangers in the calcium-form is discussed in detail. A theory of the formation of complexes of carbohydrates with metal cations is described and the mechanism of the separation of glucose and fructose on cation exchangers in the calcium-form is discussed in detail. Factors influencing the chromatographic separation of glucose and fructose on sulphonic acid cation-exchange resins are also considered. The bibliography includes 138 references.

  9. ANALYSIS AND MEASUREMENT OF STOKES LAYER FLOWS IN AN OSCILLATING NARROW CHANNEL

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The velocities of boundary layer flows between two parallel oscillating plates separated by small distance, i.e., in so called narrow channel, were theoretically and experimentally studied. The focus was on the laminar case where the Reynolds number is much smaller than the transition value. The theoretical analysis of the Stokes layer in oscillating flow over a narrow channel was made first. Then Laser Doppler Velocimeter (LDV) was employed to measure the Stokes boundary layer above an oscillating flat plate and inside the oscillating narrow channel at various numbers. At the same time, the phase angle difference along the vertical direction in both analysis and experiment were provided. The good agreements are shown between the measured results and the theoretical solution.

  10. Performance Analysis of IEEE 802.16e Wimax Physical Layer

    Directory of Open Access Journals (Sweden)

    Dr. Vineeta Saxena Nigam *,

    2014-05-01

    Full Text Available WiMAX (worldwide inter-operability for microwave access is an emerging technology for global broadband wireless system offering high speed access to mobile and broadband services. It is based on IEEE 802.16e standard. This standard only deals with MAC and PHY layer specification of network architecture. Considerable research has been done on performance analysis of PHY layer model of WiMAX system over AWGN channel model. This paper attempts performance analysis of IEEE 802.16e PHY layer model over AWGN as well as SUI channel models as SUI channel models are more realistic models based on empirical results. Different modulation schemes, coding rates, and different values of cyclic prefix are considered for comparison using BER (Bit error rate ratio and SNR (Signal to Noise ratio as performance parameters.

  11. Stochastic analysis of spectral broadening by a free turbulent shear layer

    Science.gov (United States)

    Hardin, J. C.; Preisser, J. S.

    1981-01-01

    The effect of the time-varying shear layer between a harmonic acoustic source and an observer on the frequency content of the observed sound is considered. Experimental data show that the spectral content of the acoustic signal is considerably broadened upon passing through such a shear layer. Theoretical analysis is presented which shows that such spectral broadening is entirely consistent with amplitude modulation of the acoustic signal by the time-varying shear layer. Thus, no actual frequency shift need be hypothesized to explain the spectral phenomenon. Experimental tests were conducted at 2, 4, and 6 kHz and at free jet flow velocities of 10, 20, and 30 m/s. Analysis of acoustic pressure time histories obtained from these tests confirms the above conclusion, at least for the low Mach numbers considered.

  12. Ion beam analysis of multi-layered structure in Nb/Cu system

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Shunya; Goppelt-Langer, P.; Naramoto, Hiroshi; Aoki, Yasushi; Takeshita, Hidefumi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    1997-03-01

    The dependence of H concentration on the layer thickness in H charged Nb/Cu multilayer samples has been studied using {sup 15}N resonance nuclear reaction analysis({sup 15}N-NRA) and high energy elastic recoil detection analysis(HE-ERDA). Also a simulation code has been developed for accurate simulation of the {sup 1}H({sup 15}N,{alpha}{gamma}){sup 12}C4.43 MeV {gamma}-yields at 6.385 MeV and 13.365 MeV reaction energy. The simulation are in good agreement with the experimental results. The present results show smooth increase of the H concentrations in Nb layers with increasing layer thickness. (author)

  13. Gas chromatographic analysis of plant sterols

    Science.gov (United States)

    Phytosterols are well-known for their ability to lower blood cholesterol by competing with absorption of cholesterol from the diet and reabsorption of bile cholesterol. Phytosterols as food ingredients are “Generally Recognized As Safe” (GRAS) by the FDA, and they are increasingly incorporated into ...

  14. Liquid chromatographic analysis of coal surface properties

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, K.C.

    1992-12-15

    Experiments on equilibrium adsorption of various alcohols on 60--200 mesh Illinois No. 6 coal (DECS-2; Randolph county) were performed during the July--September period. The alcohols include ethanol, methanol, isobutanol, t-butanol, 1-heptanol, 1-octanol, 1-hexadecanol, 4-methyl-2-pentanol, and 2-methyl-l-pentanol. Amounts of equilibrium adsorption of alcohols (ALCO) on 60--200 mesh Illinois No. 6 coal are 1 - 230 [times] 10[sup [minus]6] mg-ALCO/g-coal, whereas equilibrium concentrations of alcohols are 3--40 ppM. Relations between equilibrium loadings of alcohols on the coal and equilibrium concentrations of alcohols in aqueous solutions are shown to be linear.

  15. Ion chromatographic analysis of oil shale leachates

    Energy Technology Data Exchange (ETDEWEB)

    Butler, N.L.

    1990-10-01

    In the present work an investigation of the use of ion chromatography to determine environmentally significant anions present in oil shale leachates was undertaken. Nadkarni et al. have used ion chromatography to separate and quantify halogen, sulfur and nitrogen species in oil shales after combustion in a Parr bomb. Potts and Potas used ion chromatography to monitor inorganic ions in cooling tower wastewater from coal gasification. Wallace and coworkers have used ion chromatography to determine anions encountered in retort wastewaters. The ions of interest in this work were the ions of sulfur oxides including sulfite (SO{sub 3}{sup 2{minus}}), sulfate (SO{sub 4}{sup 2{minus}}), thiosulfate (S{sub 2}O{sub 3}{sup 2{minus}}), dithionite (S{sub 2}O{sub 4}{sup 2{minus}}), dithionate (S{sub 2}O{sub 6}{sup 2{minus}}), peroxyodisulfate (S{sub 2}O{sub 8}{sup 2{minus}}), and tetrathionate (S{sub 4}O{sub 6}{sup 2{minus}}), and thiocyanate (SCN{sup {minus}}), sulfide (S{sup 2{minus}}) hydrosulfide (HS{sup {minus}}), cyanide (CN{sup {minus}}), thiocyanate (SCN{sup {minus}}), and cyanate (OCN{sup {minus}}). A literature search was completed and a leaching procedure developed. 15 refs., 6 figs., 1 tab.

  16. Analysis of thermal protection characteristics of a rectangular cell filled with PCM/air layer

    Energy Technology Data Exchange (ETDEWEB)

    Ho, C.J.; Chu, C.H. [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Mechanical Engineering

    1995-12-31

    The present paper presents a numerical analysis concerning thermal protection characteristics of a rectangular composite cell filled with a solid-liquid phase change material (PCM) and air layer. Inside the composite cell the PCM layer is separated from air layer by a solid partition of negligible thickness. The buoyancy-induced flows developed in both the air-filled layer and the molten PCM zone inside the PCM layer were modeled as two-dimensional laminar Newtonian fluid flow adhering to the Boussinesq approximation. Meanwhile, two-dimensional conduction heat transfer was accounted for the unmelted solid PCM region. Delineation is made via a parametric simulation of the effects of the pertinent parameters: Ste (Stefan number), Sc (subcooling factor), Ra (Rayleigh number), aspect ratio of composite cell, A, and relative thickness ratio A{sub p}/A{sub a}, on the transient thermal protection performance of the composite cell. Results demonstrate that by means of the latent-heat absorption inside the PCM layer, heat penetration across the composite cell can be greatly retarded over an effective duration until a critical instant until the melting front of PCM reaches the partition wall. Such an effective thermal protection duration is found to be a strong function of Ra, Ste, A{sub p}/A{sub a}, and A.

  17. Infrared reflectometry of skin: Analysis of backscattered light from different skin layers

    Science.gov (United States)

    Pleitez, Miguel A.; Hertzberg, Otto; Bauer, Alexander; Lieblein, Tobias; Glasmacher, Mathias; Tholl, Hans; Mäntele, Werner

    2017-09-01

    We have recently reported infrared spectroscopy of human skin in vivo using quantum cascade laser excitation and photoacoustic or photothermal detection for non-invasive glucose measurement . Here, we analyze the IR light diffusely reflected from skin layers for spectral contributions of glucose. Excitation of human skin by an external cavity tunable quantum cascade laser in the spectral region from 1000 to 1245 cm- 1, where glucose exhibits a fingerprint absorption, yields reflectance spectra with some contributions from glucose molecules. A simple three-layer model of skin was used to calculate the scattering intensities from the surface and from shallow and deeper layers using the Boltzmann radiation transfer equation. Backscattering of light at wavelengths around 10 μm from the living skin occurs mostly from the Stratum corneum top layers and the shallow layers of the living epidermis. The analysis of the polarization of the backscattered light confirms this calculation. Polarization is essentially unchanged; only a very small fraction (skin would have the drawback that only shallow layers containing some glucose at concentrations only weakly related to blood glucose are monitored.

  18. A validated high performance thin layer chromatography method for determination of yohimbine hydrochloride in pharmaceutical preparations

    OpenAIRE

    Badr, Jihan M.

    2013-01-01

    Background: Yohimbine is an indole alkaloid used as a promising therapy for erectile dysfunction. A number of methods were reported for the analysis of yohimbine in the bark or in pharmaceutical preparations. Materials and Method: In the present work, a simple and sensitive high performance thin layer chromatographic method is developed for determination of yohimbine (occurring as yohimbine hydrochloride) in pharmaceutical preparations and validated according to International Conference of Ha...

  19. Determination of losartan potassium, quinapril hydrochloride and hydrochlorothiazide in pharmaceutical preparations using derivative spectrophotometry and chromatographic-densitometric method.

    Science.gov (United States)

    Stolarczyk, Mariusz; Maślanka, Anna; Apola, Anna; Krzek, Jan

    2013-01-01

    Two methods, spectrophotometric and chromatographic-densitometric ones, were developed for determination of losartan potassium, quinapril hydrochloride and hydrochlorothiazide in pharmaceutical preparations. Spectrophotometric method involved derivative spectrophotometry and zero order spectrophotometry. The measurements were carried out at lambda = 224.0 nm for quinapril, lambda = 261.0 nm for hydrochlorothiazide and lambda = 270.0 nm for losartan when the derivative spectrophotometry was applied and lambda = 317.0 nm when zero order spectrophotometry was applied for the determination of hydrochlorothiazide. In chromatographic-densitometric studies high performance thin layer chromatography (HPTLC) plates were used as stationary phase and a mixture of solvents n-butanol : acetic acid : water (15 : 5 : 1, v/v/v) as mobile phase. Under the established conditions good resolution of examined constituents was obtained. Retardation factor for quinapril hydrochloride was R(f) - 0.70, for losartan potassium R(f) - 0.85 and for hydrochlorothiazide R(f) - 0.78. The developed methods are characterized by high sensitivity and accuracy. For quantitative analysis, densitometric measurements were carried out at lambda = 218.0 nm for quinapril, lambda = 275.0 nm for hydrochlorothiazide and = 232.0 nm for losartan.

  20. Design and analysis of optimal multi-layer walls for time-varying thermal excitation

    Science.gov (United States)

    Bond, Danielle E. M.

    U.S. buildings are a significant source of energy consumption (about 50%) and carbon emissions (about 40%), and providing conditioning to building interiors is a major portion of that expenditure. Improving building envelope performance can reduce the amount of energy used for heating and cooling, since external walls provide an important barrier between occupied building spaces and variable ambient conditions. In general, multi-layer exterior walls tend to perform better than single-layer walls, even for the same overall R-value and thermal capacitance. This work addresses practical choices in multi-layer wall design to minimize internal temperature swings that result from outside, or ambient, temperature fluctuations. An electrical analogy is used to model one-dimensional heat conduction using RC circuits. A frequency response analysis is conducted based on a period of one day. For a fixed wall thickness, four features are optimized: materials, proportion of materials, number of layers, and material distribution. Key design features include pairing insulating and thermally massive materials, distributing layers evenly, and positioning the insulating layers at the inner- and outer-most layers of the wall (i.e., near the indoor and outdoor environments). Methods for determining the optimal proportion of each material and number of layers are also presented. Combined, these easily implemented features can reduce interior temperature fluctuations by several orders of magnitude compared to ambient temperature variations. This helps maintain steady indoor temperatures, which is more comfortable for building occupants, and supports energy management strategies, like reducing peak heating and cooling loads.

  1. Analysis and Identification of Acid-Base Indicator Dyes by Thin-Layer Chromatography

    Science.gov (United States)

    Clark, Daniel D.

    2007-01-01

    Thin-layer chromatography (TLC) is a very simple and effective technique that is used by chemists by different purposes, including the monitoring of the progress of a reaction. TLC can also be easily used for the analysis and identification of various acid-base indicator dyes.

  2. Wave analysis of the evolution of a single wave packet in supersonic boundary layer

    Science.gov (United States)

    Yermolaev, Yury G.; Yatskikh, Aleksey A.; Kosinov, Alexander D.; Semionov, Nickolay V.

    2016-10-01

    The evolution of the artificial wave packet in laminar flat-plate boundary layer was experimentally studied by hot-wire measurements at M=2. The localized disturbances were generated by pulse glow discharge. The wave analysis of evolution of wave packet was provided. It was found, that the most unstable waves are oblique, that consistent with results of linear theory.

  3. Boundary Layer Equations and Lie Group Analysis of a Sisko Fluid

    Directory of Open Access Journals (Sweden)

    Gözde Sarı

    2012-01-01

    Full Text Available Boundary layer equations are derived for the Sisko fluid. Using Lie group theory, a symmetry analysis of the equations is performed. A partial differential system is transferred to an ordinary differential system via symmetries. Resulting equations are numerically solved. Effects of non-Newtonian parameters on the solutions are discussed.

  4. In-situ RHEED analysis of atomic layer deposition and characterization of AL203 gate dielectrics

    NARCIS (Netherlands)

    Bankras, R.G.; Aarnink, A.A.I.; Holleman, J.; Schmitz, J.

    2003-01-01

    A new custom designed reactor was realized at the MESA+ cleanroom to fabricate high-k dielectrics using atomic layer deposition (ALD). Key features of the reactor are: a small reactor volume, in-situ RHEED analysis and low background pressure. The effect of precursor and purge pulse times is discuss

  5. Analysis and Identification of Acid-Base Indicator Dyes by Thin-Layer Chromatography

    Science.gov (United States)

    Clark, Daniel D.

    2007-01-01

    Thin-layer chromatography (TLC) is a very simple and effective technique that is used by chemists by different purposes, including the monitoring of the progress of a reaction. TLC can also be easily used for the analysis and identification of various acid-base indicator dyes.

  6. Composite Beam Cross-Section Analysis by a Single High-Order Element Layer

    DEFF Research Database (Denmark)

    Couturier, Philippe; Krenk, Steen

    2015-01-01

    An analysis procedure of general cross-section properties is presented. The formulation is based on the stress-strain states in the classic six equilibrium modes of a beam by considering a finite thickness slice modelled by a single layer of 3D finite elements. The theory is illustrated by applic...

  7. Simple setup for gas-phase H/D exchange mass spectrometry coupled to electron transfer dissociation and ion mobility for analysis of polypeptide structure on a liquid chromatographic time scale.

    Science.gov (United States)

    Mistarz, Ulrik H; Brown, Jeffery M; Haselmann, Kim F; Rand, Kasper D

    2014-12-01

    Gas-phase hydrogen/deuterium exchange (HDX) is a fast and sensitive, yet unharnessed analytical approach for providing information on the structural properties of biomolecules, in a complementary manner to mass analysis. Here, we describe a simple setup for ND3-mediated millisecond gas-phase HDX inside a mass spectrometer immediately after ESI (gas-phase HDX-MS) and show utility for studying the primary and higher-order structure of peptides and proteins. HDX was achieved by passing N2-gas through a container filled with aqueous deuterated ammonia reagent (ND3/D2O) and admitting the saturated gas immediately upstream or downstream of the primary skimmer cone. The approach was implemented on three commercially available mass spectrometers and required no or minor fully reversible reconfiguration of gas-inlets of the ion source. Results from gas-phase HDX-MS of peptides using the aqueous ND3/D2O as HDX reagent indicate that labeling is facilitated exclusively through gaseous ND3, yielding similar results to the infusion of purified ND3-gas, while circumventing the complications associated with the use of hazardous purified gases. Comparison of the solution-phase- and gas-phase deuterium uptake of Leu-Enkephalin and Glu-Fibrinopeptide B, confirmed that this gas-phase HDX-MS approach allows for labeling of sites (heteroatom-bound non-amide hydrogens located on side-chains, N-terminus and C-terminus) not accessed by classical solution-phase HDX-MS. The simple setup is compatible with liquid chromatography and a chip-based automated nanoESI interface, allowing for online gas-phase HDX-MS analysis of peptides and proteins separated on a liquid chromatographic time scale at increased throughput. Furthermore, online gas-phase HDX-MS could be performed in tandem with ion mobility separation or electron transfer dissociation, thus enabling multiple orthogonal analyses of the structural properties of peptides and proteins in a single automated LC-MS workflow.

  8. Electrochemical impedance spectroscopy on in-situ analysis of oxide layer formation in liquid metal

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, M., E-mail: kondo.masatoshi@tokai-u.jp [Department of Nuclear Engineering, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Suzuki, N.; Nakajima, Y. [Department of Nuclear Engineering, School of Engineering, Tokai University, 4-1-1 Kitakaname, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Tanaka, T.; Muroga, T. [National Institute for Fusion Science, Toki, Gifu 502-5292 (Japan)

    2014-10-15

    Graphical abstract: Some test materials (i.e. Fe, Cr, Y and JLF-1 steel) were immersed to liquid metal lead (Pb) mainly at 773 K as the working electrode of electrochemical impedance spectroscopy (EIS). Some oxide layers formed on the electrodes in liquid Pb were analyzed by EIS. The impedance response was summarized as semicircular Nyquist plot, and the electrical properties and the thickness of the oxide layers were evaluated in non-destructive manner. Large impedance due to the formation of Y oxide formed in liquid Pb was detected by EIS, though impedance of Fe oxide and Cr oxide could not be detected due to their small electro resistance. The time constant of the oxide layers was evaluated from the impedance information, and this value identified the types of oxides. The change of the time constant with the immersion time indicated the change of the electrical properties determined by the chemical composition and the crystal structure. The thickness of the oxide layer estimated by EIS agreed well with that evaluated by metallurgical analysis. The growth of Y oxide layer in the liquid Pb was successfully detected by EIS in non-destructive manner. - Highlights: • The electrical properties and the thickness of lead oxide layer formed in liquid Pb were obtained by electrochemical impedance spectroscopy (EIS). • The Fe oxide, Cr oxide and Fe–Cr oxide formed on the electrodes in liquid Pb were not detected by EIS due to their small electrical resistance. • The formation and the growth of Y oxide formed in liquid Pb was detected by EIS. - Abstract: Some test materials (i.e. Fe, Cr, Y and JLF-1 steel) were immersed to liquid metal lead (Pb) mainly at 773 K as the working electrode of electrochemical impedance spectroscopy (EIS). Some oxide layers formed on the electrodes in liquid Pb were analyzed by EIS. The impedance response was summarized as Nyquist plot, and the electrical properties and the thickness of the oxide layers were evaluated in non

  9. Convective stability analysis of a micropolar fluid layer by variational method

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    This paper studies Rayleigh-B'enard convection of micropolar fluid layer heated from below with realistic boundary conditions.A specific approach for stability analysis of a convective problem based on variational principle is applied to characterize the Rayleigh number for quite general nature of bounding surfaces.The analysis consists of replacing the set of field equations by a variational principle and the expressions for Rayleigh number are then obtained by using trial function satisfying the essential...

  10. 40 CFR 1065.267 - Gas chromatograph.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Gas chromatograph. 1065.267 Section 1065.267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Hydrocarbon Measurements § 1065.267 Gas...

  11. Functional chromatographic technique for natural product isolation†

    Science.gov (United States)

    Lau, Eric C.; Mason, Damian J.; Eichhorst, Nicole; Engelder, Pearce; Mesa, Celestina; Kithsiri Wijeratne, E. M.; Gunaherath, G. M. Kamal B.; Leslie Gunatilaka, A. A.

    2015-01-01

    Natural product discovery arises through a unique interplay between chromatographic purification and biological assays. Currently, most techniques used for natural product purification deliver leads without a defined biological action. We now describe a technique, referred to herein as functional chromatography, that deploys biological affinity as the matrix for compound isolation. PMID:25588099

  12. Cyclic electrophoretic and chromatographic separation methods

    NARCIS (Netherlands)

    Eijkel, Jan C.T.; Berg, van den Albert; Manz, Andreas

    2004-01-01

    A review is given of the application of cyclic analytical methods in capillary electroseparation (CE) and liquid chromatography (LC) systems. Cyclic methods have been used since the early sixties in chromatographic systems to overcome pressure limitations to resolution. From the early nineties on th

  13. Functional chromatographic technique for natural product isolation†

    OpenAIRE

    Lau, Eric C.; Mason, Damian J.; Eichhorst, Nicole; Engelder, Pearce; Mesa, Celestina; Kithsiri Wijeratne, E. M.; Gunaherath, G. M. Kamal B.; Leslie Gunatilaka, A. A.; La Clair, James J.; Chapman, Eli

    2015-01-01

    Natural product discovery arises through a unique interplay between chromatographic purification and biological assays. Currently, most techniques used for natural product purification deliver leads without a defined biological action. We now describe a technique, referred to herein as functional chromatography, that deploys biological affinity as the matrix for compound isolation.

  14. Analysis of the growth of concomitant nitride layers produced by a post-discharge assisted process

    Energy Technology Data Exchange (ETDEWEB)

    Oseguera, J. [ITESM-CEM, Carretera al Lago de Guadalupe km. 3.5 Atizapan, 52926 (Mexico)]. E-mail: joseguer@itesm.mx; Castillo, F. [ITESM-CEM, Carretera al Lago de Guadalupe km. 3.5 Atizapan, 52926 (Mexico); Gomez, A. [UFRO, Av. Francisco Salazar 01145, Temuco, Casilla 54-d (Chile); Fraguela, A. [BUAP, Rio Verde y Ave. San Claudio, San Manuel, Puebla, 72570 (Mexico)

    2006-11-23

    In the present work, the growth of concomitant nitride layers during a post-discharge process is studied. The analysis takes into account the similarities and differences between nitriding post-discharge processes and other nitriding processes, employing a mathematical simulation of nitrogen diffusion. The considered differences are related to the thermodynamic standard states, the nitrogen concentration on the surface and the sputtering of the surface (this one for plasma processes). Nitrogen diffusion and layer formation are described from the beginning of the process by means of a mathematical model.

  15. Tadpole toxicity prediction using chromatographic systems.

    Science.gov (United States)

    Fernández-Pumarega, Alejandro; Amézqueta, Susana; Fuguet, Elisabet; Rosés, Martí

    2015-10-30

    Toxicity has been emulated in tadpole species through chromatographic systems. The parameter studied to evaluate the non-specific toxicity of a compound is the narcosis concentration (Cnar), which is defined as the concentration needed for the immobilization of the organism. Because experimental investigation with animals is lengthy, costly, technically difficult, and ethically questionable, there is a great interest in developing surrogate physicochemical systems able to emulate biological systems to obtain the same information in a faster, more economic, and easier manner. In order to see which chromatographic systems would be able to emulate tadpole narcosis, both, tadpole narcosis data and data in several chromatographic and electrophoretic systems, were fitted to a linear solvation energy relationship (LSER) model. Thus, by comparison of the models it was possible to see which of the chromatographic systems were more similar to the biological one. The physicochemical systems that best emulate tadpole narcosis were an HPLC system based on an immobilized artificial membrane (IAM) column, and two micellar electrokinetic chromatography (MEKC) systems based on sodium taurocholate (STC) and a mixture of sodium dodecylsulphate (SDS) and Brij 35 as surfactants. A system based on a RP18 HPLC column also was selected for comparison because it is a common column in most analytical laboratories. To establish the models, a set of compounds with known Cnar values were analyzed in the chromatographic, and electrophoretic selected systems and, then, the retention factor (k) was correlated to the concentration of narcosis. Statistics showed that the system based on STC micelles was the best to emulate toxicity in tadpoles. The robustness and predictive ability of the developed models were validated.

  16. Liquid Chromatographic Method for Determination of Nisoldipine from Pharmaceutical Samples

    Directory of Open Access Journals (Sweden)

    Amit Gupta

    2010-01-01

    Full Text Available A simple and specific high performance thin layer chromatographic method was developed and validated for the determination of nisoldipine from tablet dosage form. The method was carried out at 320 nm after extraction of drug in methanol. The method uses aluminum plates pre-coated with silica gel 60F-254 as stationary phase and cyclohexane-ethyl acetate-toluene (3:3:4, v/v/v as mobile phase. Linearity was established over a range of 400-2400 ng per zone. Both peak area ratio and peak height ratio showed acceptable correlation coefficient i.e. more than 0.99. However we used peak area for validation purpose. Intra-day and inter-day precision was determined and found to have less than 6.0 % RSD.

  17. Noninvasive analysis of thin turbid layers using microscale spatially offset Raman spectroscopy.

    Science.gov (United States)

    Conti, Claudia; Realini, Marco; Colombo, Chiara; Sowoidnich, Kay; Afseth, Nils Kristian; Bertasa, Moira; Botteon, Alessandra; Matousek, Pavel

    2015-06-01

    Here, we demonstrate, for the first time, the extension of applicability of recently developed microscale spatially offset Raman spectroscopy (SORS), micro-SORS, from the area of cultural heritage to a wider range of analytical problems involving thin, tens of micrometers thick diffusely scattering turbid layers. The method can be applied in situations where a high turbidity of layers prevents the deployment of conventional confocal Raman microscopy with its depth resolving capability. The method was applied successfully to detect noninvasively the presence of thin, highly turbid layers within polymers, wheat seeds, and paper. An invasive, cross sectional analysis confirmed the micro-SORS findings. Micro-SORS represents a new Raman imaging modality expanding the portfolio of noninvasive, chemically specific analytical tools.

  18. Analysis of estrogens residues in milk by gas chromatographic-tandem mass spectrometry%GC-MS法测定生鲜乳中雌激素类药物残留量

    Institute of Scientific and Technical Information of China (English)

    王丽娜; 田晓玲; 陈玉艳

    2013-01-01

    本研究建立了测定生鲜乳中己烯雌酚(diethylstilbestrol)、雌二醇(estradiol)、炔雌醇(ethi-nylestradiol)、戊酸雌二醇(estradiol valerate)残留量的GC- MS法,为控制食源性动物食品的质量安全提供依据。本试验的样品经乙腈和乙酸乙酯提取,HLB固相萃取小柱净化,70℃衍生后在EI源SIM模式下进样分析。试验结果显示,己烯雌酚、雌二醇、炔雌醇含量在2.0~100.0μg/kg内、戊酸雌二醇含量在4.0~200.0μg/kg内线性关系良好,己烯雌酚、雌二醇、炔雌醇、戊酸雌二醇相关系数分别为0.9991、0.9987、0.9978、0.9983,平均回收率(n=6)为74.2%~85.8%(RSD为1.9%~9.2%)。该方法能够为测定生鲜乳中这4种雌激素类药物残留量提供可靠依据。%This research to develop and validate a rapid sensitive and specific meth-od for quantitative analytes of estrogens residues(DES, Diethylstilbestrol: E2, Es-tradiol: EE2, Ethynylestradiol: EV, Estradiol Valerate)in milk by gas chromatograph-ic-tandem mass spectrometry and be applied to estrogens residues in milk studies. The 4 kinds of components were extracted from homogenized samples with ethyl acetate fol-lowed by solid-phase extraction with HLB column and trimethylsilylation at 70 ℃ for 40 minutes, then the GC-MS method in selected ion monitoring mode(SIM)was used to an-alyze them. A good linearity was achieved with the coefficient r2 > 0.997 8(n =2). The average recovery of estrogens was more than 74.2% with RSD lower than 9.2%(n = 9). The method is sensitive, accurate, rapid, and suitable for the analysis estrogens resi-dues in milk.

  19. A Comparative Analysis of Series And Finite Element Solutions For Flow In Multi-layer Aquifers With Contiguous Layers

    Science.gov (United States)

    Wong, S.; Craig, J. R.

    2009-05-01

    Recently, Wong S. & J.R. Craig [Computational Methods in Water Resources XVII International Conference, 2008] have developed a semi-analytic series (SAS) solution method for simulating 2D steady-state groundwater flow in multi-layer aquifers with natural unconformity. The advantages of the approach include the capability to predict groundwater flow in aquifer systems with a geometrically complex structure, i.e., layers that are contiguous but vary (sometimes dramatically) in thickness across the modelled domain. The SAS approach is unorthodox compared to numerical scheme such as finite element (FE) method when handling an aquifer basin with contiguous layers. This research attempts to compare the robustness of the SAS solution with that of the FE solution under variety of different geometric conditions, including the increasing of system aspect ratios and the inclusion of pinching layers. It was found that the SAS approach is a useful benchmarking tool and that for contiguous layers, both FE methods continue to be highly accurate at even large aspect ratios. Based on the benchmarking experiments, some rules of thumb for mesh generation in FE models of regional aquifer systems with both contiguous and discontiguous layering are identified.

  20. Transient analysis for damping identification in rotating composite beams with integral damping layers

    Science.gov (United States)

    Smith, Clifford B.; Wereley, Norman M.

    1996-10-01

    The first objective of this paper is to evaluate the performance of damping identification algorithms. The second objective is to determine the feasibility of damping augmentation in rotating composite beams via passive constrained layer damping (PCLD). Damping identification schemes were applied to four rectangular cross-section laminated composite beams with cocured integral damping layers over the span of the beam. The cocured beam consisted of a twenty-ply balanced and symmetric cross-ply Gr/Ep composite host structure, a top and bottom damping layer of viscoelastic material (VEM), and a 2-ply Gr/Ep constraining layer sandwiching the viscoelastic material to the host structure. Four VEM thicknesses were considered: 0, 5, 10, and 15 mils. The cantilevered beams were tested at rotational speeds ranging from 0 to 900 RPM in a vacuum chamber. Excitation in bending was provided using piezo actuators, and the bending response was measured using full strain gauge bridges. Transient data were analysed using logarithmic decrement, a Hilbert transform technique, and an FFT- based moving block analysis. When compared to the beam with no VEM, a 19.2% volume fraction (15 mil layer) of viscoelastic in the beam produced a 400% increase in damping ratio in the non-rotating case, while at 900 RPM, the damping ratio increased only 360%. Overall structural damping was reduced as a function of RPM, due to centrifugal stiffening.