Sample records for chromatographic columns

  1. Ion chromatographic separation of inorganic ions using a combination of hydrophilic interaction chromatographic column and cation-exchange resin column. (United States)

    Arai, Kaori; Mori, Masanobu; Hironaga, Takahiro; Itabashi, Hideyuki; Tanaka, Kazuhiko


    A combination of hydrophilic interaction chromatographic (HILIC) column and a weakly acidic cation-exchange resin (WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography (IC). Firstly, the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions. The columns used were SeQuant ZIC-HILIC (ZIC-HILIC) with a sulfobetaine-zwitterion stationary phase (ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase (HILIC-10). When using tartaric acid as the eluent, the HILIC columns indicated strong retentions for anions, based on ion-pair interaction. Especially, HILIC-10 could strongly retain anions compared with ZIC-HILIC. The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I(-) > NO3(-) > Br(-) > Cl(-) > H2PO4(-). However, since HILIC-10 could not separate analyte cations, a WCX column (TSKgel Super IC-A/C) was connected after the HILIC column in series. The combination column system of HILIC and WCX columns could successfully separate ten ions (Na+, NH4+, K+, Mg2+, Ca2+, H2PO4(-), Cl(-), Br(-), NO3(-) and I(-)) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6. The relative standard deviations (RSDs) of analyte ions by the system were in the ranges of 0.02% - 0.05% in retention times and 0.18% - 5.3% in peak areas through three-time successive injections. The limits of detection at signal-to-noise ratio of 3 were 0.24 - 0.30 micromol/L for the cations and 0.31 - 1.2 micromol/L for the anions. This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.


    Institute of Scientific and Technical Information of China (English)

    Fangwei Wang; Yongdong Liu; Jing Chen; Zhiguo Su


    Protein expression in E. coli often results in the formation of a kind of protein aggregate called inclusion body. Conversion of the inactive protein aggregate into biologically active protein is a key step in production of recombinant products. Conventional dilution refolding technique suffers from disadvantages of low recovery and low concentration. Various chromatographic refolding techniques have been developed over the last few years. These include size-exclusion chromatography, ion exchange chromatography, hydrophobic interaction chromatography and different affinity chromatography. A successful strategy is the use of gradient elution in column control which provides a gentle and gradual change of the solution environment for the macromolecule to refold at nano-scale. The gradient refolding at column scale could minimize misfolding and aggregation which are induced by sudden change of the solution in conventional refolding operation.

  3. Ion chromatographic separation of inorganic ions using a combination of hydrophilic interaction chromatographic column and cation-exchange resin column

    Institute of Scientific and Technical Information of China (English)

    Kaori ARAI; Masanobu MORI; Takahiro HIRONAGA; Hideyuki ITABASHI; Kazuhiko TANAKA


    A combination of hydrophilic interaction chromatographic ( HILIC ) column and a weakly acidic cation-exchange resin (WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography ( IC ).Firstly,the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions.The columns used were SeQuant ZIC-HILIC (ZIC-HILIC) with a sulfobetainezwitterion stationary phase (ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase (HILIC-10).When using tartaric acid as the eluent,the HILIC columns indicated strong retentions for anions,based on ion-pair interaction.Especially,HILIC-10 could strongly retain anions compared with ZIC-HILIC. The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I- > NO3- > Br- > Cl- >H2PO4-.However,since HILIC-10 could not separate analyte cations,a WCX column (TSKgel Super IC-A/C) was connected after the HILIC column in series.The combination column system of HILIC and WCX columns could successfully separate ten ions (Na+,NH4+,K+,Mg2+,Ca2+,H2PO4-,Cl-,Br-,NO3- and I-) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6.The relative standard deviations (RSDs) of analyte ions by the system were in the ranges of 0.02% - 0.05% in retention times and 0.18% - 5.3% in peak areas through three-time successive injections.The limits of detection at signal-to-noise ratio of 3 were 0.24 - 0.30 μmol/L for the cations and 0.31 - 1.2 μmol/L for the anions.This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.

  4. Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column (United States)

    Huz, Kateryna


    RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

  5. The selection of suitable columns for a reversed-phase liquid chromatographic separation of beta-lactam antibiotics and related substances via chromatographic column parameters. (United States)

    Zhang, Wei-qing; Hu, Qiu-xin; Zhang, Xia; Li, Ya-ping; Wang, Ming-juan; Hu, Chang-qin


    The selection of RP-LC columns suitable for a particular analysis in official compendia is difficult as only a general description of the stationary phase in the description of a LC method is given. General methods to characterize RP-LC columns often assume that each of the column parameters is equally important. This can cause the user to select columns inappropriate for particular analyses. This paper focuses on the relationship between the critical peak pairs and the column parameters (H, S, A, B, and C) in the Snyder/Dolan column characterization methodology to find the key parameters influencing real separations. Some varieties of β-lactam antibiotics and their related compounds were used as test compounds. We found column parameter A to be the most important factor affecting their separation. Parameters B and C also played an important role in some separation processes. This indicated that the hydrogen bonding of column and solute can directly affect the separation of β-lactam antibiotics. Choosing columns for which column parameter A is near 0.1 can facilitate the ideal separations of impurities from β-lactam antibiotics. The most suitable column for any common pharmaceutical analysis could be selected easily if the key column parameters would be given in the description of the chromatographic method. For these reasons, key column parameters should be listed in the monographs of official compendia.

  6. Estimation of Chromatographic Columns Performances using Computer Tomography and CFD Simulations

    DEFF Research Database (Denmark)

    Schmidt, Irma; Lottes, Florian; Minceva, Mirjana;


    The flow inside a chromatographic column depends decisively on the packed bed inside. Non‐destructive X‐ray computed tomography (CT) was applied as a novel measurement technique to visualize the distribution of velocity and axial dispersion coefficients in preparative scale columns. The results s...

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

  8. Potentiality of optical diffraction grating technology in the fabrication of miniaturized multicapillary chromatographic and electrophoresis columns. (United States)

    Samsonov, Y N


    A possible way of fabricating miniaturized multicapillary columns for gas and liquid chromatographs or electrophoresis devices containing many thousands of identical channels with a width (or depth) of approximately 1-30 microm by means of industrial technology for the production of optical plane reflecting diffraction gratings is proposed.


    Institute of Scientific and Technical Information of China (English)

    Guang Yang; Li-na Zhang; Xiao-peng Xiong; Xiao-dong Cao; Yong-liang Yang


    Microporous regenerated cellulose gel particles were prepared by mixing cellulose cuoxam with silk fibroin as pore former, and the mean pore size and pore volume of the particles were 525 nm and 7.27 mL g-1, respectively. A preparative size-exclusion chromatography (SEC) column (550 mm × 20 mm) packed with the cellulose gel particles was used for the fractionation of two polysaccharides Dextran 07 (Mw=7.14×104, d = 1.7) and Dextran 50 (Mw = 50.5×104,d = 3.8) in water phase. The fractionation range of the stationary phase covered Mw from 3 × 103 to 1.1 × 106. The daily throughput was 2.9 g for Dextran 07 (D07) and 4.3 g for Dextran 50 (D50) with a flow-rate of 1.5 mL min-1. The fractions obtained by using the SEC were analyzed by an analytical SEC combined with laser light scattering (LLS), and the polydispersity indices of fractions for Dextran 07 and Dextran 50 were determined to be 1.34-1.57 and 1.53-3.36,respectively. The preparative SEC is a simple, rapid, and suitable means not only for the fractionation of polysaccharides in water but also for other polymers in organic solvents.``

  10. Utilization of a diol-stationary phase column in ion chromatographic separation of inorganic anions. (United States)

    Arai, Kaori; Mori, Masanobu; Kozaki, Daisuke; Nakatani, Nobutake; Itabashi, Hideyuki; Tanaka, Kazuhiko


    We describe the ion chromatographic separation of inorganic anions using a diol-stationary phase column (-CH(OH)CH(2)OH; diol-column) without charged functional groups. Anions were separated using acidic eluent as in typical anion-exchange chromatography. The retention volumes of anions on the diol-column increased with increasing H(+) concentration in the eluent. The anion-exchange capacities of diol-columns in the acidic eluent (pH 2.8) were larger than that of zwitterionic stationary phase column but smaller than that of an anion-exchange column. The separation of anions using the diol-column was strongly affected by the interaction of H(+) ions with the diol-functional groups and by the types of the eluents. In particular, the selection of the eluent was very important for controlling the retention time and resolution. Good separation was obtained using a diol-column (HILIC-10) with 5 mM phthalic acid as eluent. The limits of detection at a signal-to-noise ratio of 3 ranged from 1.2 to 2.7 μM with relative standard deviations (RSD, n=5) of 0.04-0.07% for the retention time and 0.4-2.0% for the peak areas. This method was successfully applied to the determination of H(2)PO(4)(-), Cl(-), and NO(3)(-) in a liquid fertilizer sample.

  11. Improvement in Liquid Chromatographic Performance of Organic Polymer Monolithic Capillary Columns with Controlled Free-Radical Polymerization. (United States)

    Gama, Mariana R; Aggarwal, Pankaj; Liu, Kun; Lee, Milton L; Bottoli, Carla B G


    Capillary columns containing butyl or lauryl methacrylate monoliths were prepared using two different free-radical polymerization methods: conventional free-radical polymerization and controlled/living free-radical polymerization, both initiated thermally, and these methods were compared for the first time. Both monolith morphology and chromatographic efficiency were compared for the synthesized stationary phases using scanning electronic microscopy (SEM) and capillary liquid chromatography, respectively. Columns prepared using controlled method gave better chromatographic performance for both monomers tested. The lauryl-based monolith showed 7-fold improvement in chromatographic efficiency with a plate count of 42,000 plates/m (corrected for dead volume) for a non-retained compound. Columns fabricated using controlled polymerization appeared more homogenous radially with fused small globular morphologies, evaluated by SEM, and lower column permeability. The columns were compared with respect to resolving power of a series of alkylbenzenes under isocratic and gradient elution conditions.

  12. Determinations of gas-liquid partition coefficients using capillary chromatographic columns. Alkanols in squalane. (United States)

    Tascon, Marcos; Romero, Lílian M; Acquaviva, Agustín; Keunchkarian, Sonia; Castells, Cecilia


    This study focused on an investigation into the experimental quantities inherent in the determination of partition coefficients from gas-liquid chromatographic measurements through the use of capillary columns. We prepared several squalane - (2,6,10,15,19,23-hexamethyltetracosane) - containing columns with very precisely known phase ratios and determined solute retention and hold-up times at 30, 40, 50 and 60°C. We calculated infinite dilution partition coefficients from the slopes of the linear regression of retention factors as a function of the reciprocal of the phase ratio by means of fundamental chromatographic equations. In order to minimize gas-solid and liquid-solid interface contributions to retention, the surface of the capillary inner wall was pretreated to guarantee a uniform coat of stationary phase. The validity of the proposed approach was first tested by estimating the partition coefficients of n-alkanes between n-pentane and n-nonane, for which compounds data from the literature were available. Then partition coefficients of sixteen aliphatic alcohols in squalane were determined at those four temperatures. We deliberately chose these highly challenging systems: alcohols in the reference paraffinic stationary phase. These solutes exhibited adsorption in the gas-liquid interface that contributed to retention. The corresponding adsorption constant values were estimated. We fully discuss here the uncertainties associated with each experimental measurement and how these fundamental determinations can be performed precisely by circumventing the main drawbacks. The proposed strategy is reliable and much simpler than the classical chromatographic method employing packed columns.

  13. Validation of a column liquid chromatographic method for the analysis of pramipexole and its five impurities. (United States)

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


    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.

  14. Chromatographic determination of cyanoglycosides prunasin and amygdalin in plant extracts using a porous graphitic carbon column. (United States)

    Berenguer-Navarro, V; Giner-Galván, R M; Grané-Teruel, N; Arrazola-Paternina, G


    The determination of cyanogenic compounds in plants is often performed by HPLC. However, in this analysis, interferences due to compounds in the matrix, such as tannins and other pigments, are encountered, especially in roots and leaves. A new method is proposed for determining the cyanogenic glycosides amygdalin (D-mandelonitrile beta-D-gentiobioside) and prunasin (D-mandelonitrile beta-D-glucoside) in almond tree tissues, using poly(vinylpyrrolidone) or active carbon as scavengers for extracting cyanogenic compounds from roots or leaves, respectively. A new chromatographic approach for conducting the analysis is also discussed herein. The advantages of a Hypercarb column for the analysis of prunasin in roots are shown. The correlation coefficient with a reference method is high (>0.99), and statistical tests prove that the two methods are equivalent. In addition, the results provide evidence that prunasin is the only cyanoglycoside present in almond tree roots.

  15. High-performance liquid chromatographic column packings with different particle sizes: chromatographic behavior for the quality analysis of HuanglianShangqing pill. (United States)

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


    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.

  16. Studies on column size scale-up and flow profile in conical shape liquid chromatographic column of 10° by visualization method

    Institute of Scientific and Technical Information of China (English)

    Guan Wenna; Tan Feng; Guan Yafeng


    An improved visualization device made of polymethyl methacrylate (PMMA) was used to study the 3D flow profile inside conical columns of a 10° opening angle packed with C18 phase.The outside wall of the conical columns was rectangular in shape in order to improve the transparency property of the column wall and reduce the deformation of the image for better observation of the flow profiles of colored solutes inside the column.The influence of flow rate,particle size and shape on the flow profile of a colored band were studied on a 5-cm-long column and a scaled-up column of four fold in volume.It was found that the flow rates of the mobile phase had little influence on the flat flow profile of the iodine band while the properties of the stationary phase had a certain influence on them.We observed that the flow profiles of the scaled-up column were flat during the whole chromatographic process,and the efficiency and resolution of the column were also increased in accordance with theoretical prediction.The experimental results proved that the 10° conical columns can be proportionally scaled up while still keeping the flat flow profile,sample load per unit volume of packing material,and column efficiency,which are superior to the conventional column.

  17. Development of micromachined preconcentrators and gas chromatographic separation columns by an electroless gold plating technology (United States)

    Kuo, C.-Y.; Chen, P.-S.; Chen, H.-T.; Lu, C.-J.; Tian, W.-C.


    In this study, a simple process for fabricating a novel micromachined preconcentrator (μPCT) and a gas chromatographic separation column (μSC) for use in a micro gas chromatograph (μGC) using one photomask is described. By electroless gold plating, a high-surface-area gold layer was deposited on the surface of channels inside the μPCT and μSC. For this process, (3-aminopropyl) trimethoxysilane (APTMS) was used as a promoter for attaching gold nanoparticles on a silicon substrate to create a seed layer. For this purpose, a gold sodium sulfite solution was used as reagent for depositing gold to form heating structures. The microchannels of the μPCT and μSC were coated with the adsorbent and stationary phase, Tenax-TA and polydimethylsiloxane (DB-1), respectively. μPCTs were heated at temperatures greater than 280 °C under an applied electrical power of 24 W and a heating rate of 75 °C s‑1. Repeatable thermal heating responses for μPCTs were achieved; good linearity (R 2  >  0.9997) was attained at three heating rates for the temperature programme for the μSC (0.2, 0.5 and 1 °C s‑1). The volatile organic compounds (VOCs) toluene and m-xylene were concentrated over the μPCT by rapid thermal desorption (peak width of half height (PWHH)  7900. The VOCs acetone, benzene, toluene, m-xylene and 1,3,5-trimethylbenzene were also separated on the μSC as evidenced by their different retention times (47–184 s).

  18. Comparison of two gas-liquid chromatograph columns for the analysis of fatty acids in ruminant meat. (United States)

    Alves, Susana P; Bessa, Rui J B


    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.

  19. Ion Chromatographic Method with Post-Column Fuchsin Reaction for Measurement of Bromate in Chlorinated Water

    Directory of Open Access Journals (Sweden)

    Homer C. Genuino


    Full Text Available An ion chromatographic method that employs a post-column reaction with fuchsin and spectrophotometric detection was optimized for measuring bromate (BrO3- in water. BrO3- is converted to Br2 by sodium metabisulfite and then reacted with acidic fuchsin to form a red-colored product that strongly absorbs at 530 nm. The reaction of BrO3- and fuchsin reagent is optimum at pH 3.5 and 65 oC. The method has a limit of quantitation of 4.5 µg L-1 and is linear up to 150 µg L-1 BrO3-. Recoveries from spiked samples were high ranging from 95 to 102 % using external standard calibration and 87 to 103 % using standard addition method. Intra-batch and inter-batch reproducibility studies of the method resulted to RSD values ranging from 0.62 to 2.01 % and percent relative error of 0.12 to 2.94 % for BrO3- concentrations of 10 µg L-1 and 50 µg L-1. This method is free of interferences from common inorganic anions at levels typically found in chlorinated tap drinking water without preconcentration. The optimized method can be applied to trace analysis of bromate in chlorinated tap drinking water samples.

  20. Studies on Chromatographic Properties of Perhydroxycucurbit[6]uril as a New Type of Gas Chromatographic Column Packing Material

    Institute of Scientific and Technical Information of China (English)

    LI Lai-Sheng; WANG Shang-Wen; CHEN Xiong-Quan; LIU Chao; XU Li-Li


    Perhydroxycucurbit[6]uril{(HO)12CB[6]}has been used successfully as a stationary phase for packed column gas chromatography for the first time.Perhydroxycucurbit[6]uril stationary phase(PSP)exhibited wide operational temperature,outstanding thermostability and good selectivities to various organic compounds,such as alkanes,aromatic hydrocarbons,alcohols,esters,ketones,amines,etc.It was also found that some positional isomers,such as disubstituted benzenes could be well separated on this column.PSP has excellent separation abilities to some complicate samples,for example,commercial toilet water.Some mechanism of the new packing for GC-separation was preliminarily discussed.It was observed that the partial inclusion complexation of PSP with analytes could improve separation selectivity and column efficiency,instead of complete inclusion.Moreover,PSP exhibited low baseline shift even at dramatically programmed temperature for complicate samples covering a wide boiling point range so as to fast assay.

  1. [A simple preparation method of an electric heating apparatus for heating capillary chromatographic columns and its application in liquid chromatography-mass spectrometry system]. (United States)

    Jin, Zuyao; Lü, Yayao; Zhou, Shanshan; Hao, Feiran; Fu, Bin; Ying, Wantao; Qian, Xiaohong; Zhang, Yangjun


    For deep coverage of proteome, especially in performing qualitative identification and quantitative analysis of low-abundance proteins, the most commonly used method is the application of a longer capillary chromatographic column or a capillary column packed with smaller particle sizes. However, this causes another problem, the very high back pressure which results in liquid leaks in some connection parts in a liquid chromatograph. To solve this problem, an electric heating apparatus was developed to raise the temperature of a capillary column for reducing its back pressure, which was further applied in a capillary high performance liquid chromatography-tandem mass spectrometry system (cHPLC-MS/MS), and evaluated in the terms of chromatographic column back pressure and chromatographic column efficiency using bovine serum albumin (BSA) tryptic digests and yeast tryptic digests, separately. The results showed that at the optimum current, our electric heating apparatus could reduce the column pressure of a capillary column packed with 3 µm packing materials by at least 50% during the separation of BSA tryptic digestion and yeast tryptic digestion, compared with that without electric heating. The column efficiency was also increased slightly. This suggested that the electric heating apparatus can significantly reduce the column pressure, which provides an efficient way to use capillary chromatographic columns packed with smaller sizes of particles at a lower pressure.

  2. Cutting through the confusion in high performance liquid chromatographic column technology%非线性电泳

    Institute of Scientific and Technical Information of China (English)



    Column packings continue to evolve as the needs of users for high efficiency, high resolution and highly sensitive high performance liquid chromatographic ( HPLC ) analysis drive further developments. In comparing and contrasting modern HPLC columns technologies, diameters of column packings and particle materials are covered. Some products and applications of modern HPLC columns are provided. Future directions in packing developments are predicted in this introductory article.%@@ 电泳大家当已耳熟能详了,它发现于18世纪初期,有悠久的历史.电泳因Tiselius而进入分离领域,为蛋白质科学的建立和发展立下了汗马功劳.其贡献至今不息,一直是生物学家的掌中宝.

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


    Amir Farshchi; Golbarg Ghiasi; Gholamreza Bahrami


    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...

  4. Evaluation of the retention pattern on ionic liquid columns for gas chromatographic analyses of fatty acid methyl esters. (United States)

    Lin, Chen-Chen; Wasta, Ziar; Mjøs, Svein A


    Fatty acid methyl esters from marine sources were analyzed by gas chromatography-mass spectrometry on three ionic liquid columns, SLB-IL61, SLB-IL82 and SLB-IL100 (Supelco). Retention indices (equivalent chain lengths) are reported for more than 100 compounds and the overlap patterns are evaluated from these data. The influence of chromatographic conditions on the retention indices of unsaturated fatty acid methyl esters is also evaluated. Compared to typical alternative phases the retention patterns on all three columns are highly dependent on the conditions. The SLB-IL61 phase had overlaps between nutritionally important fatty acids that could not be resolved by changing the chromatographic conditions. This column is therefore regarded as unsuitable for clinical and nutritional studies of the fatty acid composition, but similar overlaps may be avoided on IL82 and IL100. On all three columns double bonds close to the carboxyl group in the analytes contribute with limited retention, which makes it challenging to predict the retention of polyunsaturated fatty acid methyl esters.

  5. 1.1 μm superficially porous particles for liquid chromatography: part II: column packing and chromatographic performance. (United States)

    Blue, Laura E; Jorgenson, James W


    The predicted advantages of superficially porous particles over totally porous particles are decreased eddy dispersion, longitudinal diffusion, and resistance to mass transfer contributions to the theoretical plate height. While sub-2 micron superficially porous particles are commercially available, further improvements in performance are predicted by decreasing the particle diameter and decreasing the porous layer thickness. 1.1 μm superficially porous particles with 187Å pores have been synthesized using a layer-by-layer method tuned for production of smaller diameter particles. Following synthesis, these particles were packed into 30 μm i.d. capillary columns and their chromatographic performance evaluated using electrochemical detection. Based on the initial studies, the column efficiency did not meet theory, but was similar to the commercially available products tested. It is believed that the column packing process plays a critical role in the sub-par column performance. To determine if column efficiency could be predicted by solvent-particle interactions, in-solution optical microscopy and sedimentation velocity of particles in various slurry solvents were investigated and compared to column performance. Aggregating slurry solvents, such as methanol were found to produce columns with increased efficiency. The hmin for a column packed with an acetone slurry and a methanol slurry at 3mg/mL were found to be 6.3 and 3.5, respectively. Increasing the slurry concentration to 25mg/mL further improved the efficiency, producing a column with an hmin of 2.6. These efficiency results were accurately predicted by in-solution optical microscopy.

  6. 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


    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.

  7. Combined column-mobile phase mixture statistical design optimization of high-performance liquid chromatographic analysis of multicomponent systems. (United States)

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


    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.

  8. Gas chromatographic separation of fatty acid esters of cholesterol and phytosterols on an ionic liquid capillary column. (United States)

    Hammann, Simon; Vetter, Walter


    Steryl esters are high molecular weight compounds (600-700g/mol) regularly present as a minor lipid class in animal and plant lipids. Different sterol backbones (e.g., cholesterol, β-sitosterol and brassicasterol) which can be esterified with various fatty acids can result in highly complex steryl ester patterns in food samples. The gas chromatographic (GC) analysis of intact steryl esters is challenging, since high elution temperatures are required for their elution. On nonpolar GC phases, steryl esters with fatty acids with differing degree of unsaturation (e.g., oleate and linoleate) cannot be separated and there are only few polar columns available with sufficient temperature stability. In this study, we used gas chromatography with mass spectrometry (GC/MS) and analyzed intact steryl esters on a commercial room temperature ionic liquid (RTIL) column which was shortened to a length of 12m. The column separated the steryl esters both by total carbon number and by degree of unsaturation of the fatty acid. For instance, cholesteryl esters with stearic acid (18:0), oleic acid (18:1n-9), linoleic acid (18:2n-6) and α-linolenic acid (18:3n-3) could be resolved (R≥1.3) from each other. By analysis of synthesized standard substances, the elution orders for different steryl backbones and different fatty acids on a given sterol backbone could be determined. Analysis of spreads and plant oils allowed to determine retention times for 37 steryl esters, although a few co-elutions were observed. The ionic liquid column proved to be well-suited for the analysis of intact steryl esters.

  9. Improved high performance liquid chromatographic separation of anthocyanin compounds from grapes using a novel mixed-mode ion-exchange reversed-phase column. (United States)

    McCallum, Jason L; Yang, Raymond; Young, J Christopher; Strommer, Judith N; Tsao, Rong


    A novel mixed mode HPLC method using a column combining both ion-exchange and reversed-phase separation mechanisms has been developed to facilitate analysis of anthocyanins in grapes. Chromatographic performance and subsequent analysis of anthocyanidin diglucosides and acylated compounds are significantly improved using the new column, compared to those associated with conventional C18 reversed-phase methods. The mixed mode column produces a distinctive eluting pattern for the different anthocyanin subgroups, avoiding overlaps found with C18 columns. The enhanced chromatographic resolution provides nearly complete separation of 37 anthocyanin types, and permits detection of delphinidin 3-O-(6''-O-caffeoyl) beta-D-glucoside for the first time in extracts of skins from Concord grapes.

  10. A Gas Chromatographic Analysis of Light Hydrocarbons on a Column Packed with Modified Silica Gel

    Institute of Scientific and Technical Information of China (English)


    A one-meter long column packed with silica gel is used to separate light hydrocarbons. The silica gel has been modified with several kinds of gas chromatography stationary phases. Among these, PEG 2000 shows fairly good effect when using 80-100 meshes silica gel for the separation of mixture of methane, ethane, ethylene, acetylene, propane, propylene and n-, i-butane. The different behavior of silica gel between batch to batch is also found. When silica gel is coated with a small amount of Al2O3 prepared with sol-gel method, better resolution has been observed on a 2-meter column compared with the non-modified silica gel.

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

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


    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.

  12. 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. (United States)

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


    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.

  13. A new on-line, in-tube pre-column derivatization technique for high performance liquid chromatographic determination of azithromycin in human serum. (United States)

    Bahrami, Gholamreza; Mohammadi, Bahareh


    Pre-column derivatization methods for high performance liquid chromatographic assay of specific pharmaceutical agents using 9-fluorenylmethyl chloroformate (FMOC-Cl) have received special attention because highly fluorescent and stable adducts are provided by these methods. However, unlike the post-column on-line techniques, long derivatization time is needed and the reaction cannot be well controlled. A new, sensitive and fast pre-column on-line derivatization technique coupled with high-performance liquid chromatography using FMOC-Cl as labeling agent is described and validated for determination of azithromycin in human serum. After extraction of the drug from serum, the residue was reconstituted in mixture of acetonitrile-phosphate buffer (3:1, v/v; pH 8.5) and directly injected onto the chromatographic system. Continuous on-line derivatization and analysis of the compounds were successfully performed using in-tube elution of FMOC-Cl. The total time needed for derivatization and chromatographic analysis of the drug was 13 min. The assay was reliable and reproducible, with limit of quantification of 10 ng/ml. The described technique may offer significant advantages over existing off-line derivatization methods using FMOC-Cl.

  14. Rapid determination of lidocaine solutions with non-column chromatographic diode array UV spectroscopy and multivariate calibration. (United States)

    Wiberg, Kent; Hagman, Anders; Jacobsson, Sven P


    A new method for the rapid determination of pharmaceutical solutions is proposed. A conventional HPLC system with a Diode Array Detector (DAD) was used with no chromatographic column connected. As eluent, purified water (Milli Q) was used. The pump and autosampler of the HPLC system were mainly utilised as an automatic and convenient way of introducing the sample into the DAD. The method was tested on the local anaesthetic compound lidocaine. The UV spectrum (245-290 nm) from the samples analysed in the detector was used for multivariate calibration for the determination of lidocaine solutions. The content was determined with PLS regression. The effect on the predictive ability of three factors: flow, data-collection rate and rise time as well as two ways of exporting a representative UV spectrum from the DAD file collected was investigated by means of an experimental design comprising 11 experiments. For each experiment, 14 solutions containing a known content of lidocaine were analysed (0.02-0.2 mg ml(-1)). From these 14 samples two calibration sets and two test sets were made and as the response in the experimental design the Root Mean Square Error of Prediction (RMSEP) values from the predictions of the two test sets were used. When the factor setting giving the lowest RMSEP was found, this setting was used when analysing a new calibration set of 12 lidocaine samples (0.1-0.2 mg ml(-1)). This calibration model was validated by two external test sets, A and B, analysed on separate occasions for the evaluation of repeatability (test set A) and determination over time (test set B). For comparison, the reference method, liquid chromatography, was also used for analysis of the ten samples in test set B. This comparison of the two methods was done twice on different occasions. The results show that in respect of accuracy, precision and repeatability the new method is comparable to the reference method. The main advantages compared with liquid chromatography are the

  15. Development and validation of a pre-column reversed phase liquid chromatographic method with fluorescence detection for the determination of primary phenethylamines in dietary supplements and phytoextracts. (United States)

    Gatti, Rita; Lotti, Cinzia


    A sensitive and selective reversed-phase liquid chromatographic (RP-LC) method was developed and validated to determine octopamine, tyramine and Tyrosine (Tyr) in complex matrices as formulations and phytoextracts (Citrus aurantium), after pre-column derivatization with o-phthaldialdehyde (OPA) reagent. The chromatographic separations were performed at room temperature on a Phenomenex Luna C18 column using methanol and sodium acetate buffer (pH 5.5) by varying composition gradient elution as mobile phase and detected flurometrically at λ(em)=455 nm with λ(ex)=340 nm. The results obtained by the proposed method were compared with those achieved by a validated direct RP-LC method with fluorescence detection at λ(em)=310 nm with λ(ex)=275 nm, as reference method, using a Phenomenex Gemini C18 column under isocratic elution conditions with acetonitrile and sodium 1-heptanesulphonate (pH 3), as mobile phase. The higher sensitivity of the derivatization method (detection limit about 0.06 pmol) allowed the sure determination of octopamine present in traces in the examined samples. The repeatability of method (RSD) was ≤1.90% and there was no significant difference between repeatability and intermediate precision data. Recovery studies showed good results 99.5-101.3% with RSD ranging from 0.8 to 1.2%. All analyses were performed by mild conditions in absence of preliminary difficult extraction methodologies or laborious step of sample pre-treatment.

  16. 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


    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...

  17. Structural variation of solid core and thickness of porous shell of 1.7 μm core-shell silica particles on chromatographic performance: narrow bore columns. (United States)

    Omamogho, Jesse O; Hanrahan, John P; Tobin, Joe; Glennon, Jeremy D


    Chromatographic and mass transfer kinetic properties of three narrow bore columns (2.1×50 mm) packed with new core-shell 1.7 μm EIROSHELL™-C(18) (EiS-C(18)) particles have been studied. The particles in each column varied in the solid-core to shell particle size ratio (ρ), of 0.59, 0.71 and 0.82, with a porous silica shell thickness of 350, 250 and 150 nm respectively. Scanning and transmission electron microscopy (SEM and TEM), Coulter counter analysis, gas pycnometry, nitrogen sorption analysis and inverse size exclusion chromatography (ISEC) elucidated the physical properties of these materials. The porosity measurement of the packed HILIC and C(18) modified phases provided the means to estimate the phase ratios of the three different shell columns (EiS-150-C(18), EiS-250-C(18) and EiS-350-C(18)). The dependence of the chromatographic performance to the volume fraction of the porous shell was observed for all three columns. The naphtho[2,3-a]pyrene retention factor of k'∼10 on the three EiS-C(18s) employed to obtain the height equivalents to theoretical plates (HETPs) data were achieved by varying the mobile phase compositions and applying the Wilke and Chang relationship to obtain a parallel reduced linear velocity. The Knox fit model gave the coefficient of the reduce HETPs for the three EiS-C(18s). The reduced plate height minimum h(min)=1.9 was achieved for the EiS-150-C(18) column, and generated an efficiency of over 350,000 N/m and h(min)=2.5 equivalent to an efficiency of 200,000 N/m for the EiS-350-C(18) column. The efficiency loss of the EiS-C18 column emanating from the system extra-column volume was discussed with respect to the porous shell thickness.

  18. Chromatographic studies of unusual on-column degradations of aniline compounds on XBridge Shield RP18 column in high pH aqueous mobile phase. (United States)

    Wang, Fang; Liu, Xiao-Keng; Lai, Susanna; Fang, Jan; Semin, David


    This paper reports unusual on-column degradations of aniline compounds on Waters XBridge Shield RP18 column when ammonium hydroxide in water and acetonitrile were used as mobile phases in liquid chromatography. The change of the level of on-column degradation of a model compound (Compound 1) with time was observed in the first fifteen injections when started at 60 °C. During a subsequent cooling program from 60 °C to 10 °C with a 10 °C interval, the levels of the degradation products of Compound 1 changed with the change of temperature and reached a maximum at 40 °C. The on-column degradation of Compound 1 was observed when started at 10 °C in the first injection, however, the magnitude of the change of the level of on-column degradation of Compound 1 with time in the first fifteen injections was much smaller than that at 60 °C. During a subsequent heating program from 10 to 60 °C with a 10 °C interval, the levels of the degradation products of Compound 1 increased with the increase in temperature but without a maximum. The change of the degradation product levels of this model compound in the heating process is not super-imposable with that in the cooling process, which demonstrates the degree of the degradation also depends on the heating or cooling process. Column history studies demonstrated that the on-column degradation of Compound 1 changed dramatically on the used columns at both starting temperatures while the dependency of heating and cooling processes on on-column degradation still existed. The unusual on-column degradation of Compound 1 on the used columns can be regenerated in a very similar fashion with an acetic acid column-wash procedure, but is not identical to that on the new column. Similar degradations of other commercially available aniline compounds were also observed with this high pH aqueous mobile phase system.

  19. One-step column chromatographic extraction with gradient elution followed by automatic separation of volatiles, flavonoids and polysaccharides from Citrus grandis. (United States)

    Han, Han-Bing; Li, Hui; Hao, Rui-Lin; Chen, Ya-Fei; Ni, He; Li, Hai-Hang


    Citrus grandis Tomentosa is widely used in traditional Chinese medicine and health foods. Its functional components include volatiles, flavonoids and polysaccharides which cannot be effectively extracted through traditional methods. A column chromatographic extraction with gradient elution was developed for one-step extraction of all bioactive substances from C. grandis. Dried material was loaded into a column with petroleum ether: ethanol (8:2, PE) and sequentially eluted with 2-fold PE, 3-fold ethanol: water (6:4) and 8-fold water. The elutes was separated into an ether fraction containing volatiles and an ethanol-water fraction containing flavonoids and polysaccharides. The later was separated into flavonoids and polysaccharides by 80% ethanol precipitation of polysaccharides. Through this procedure, volatiles, flavonoids and polysaccharides in C. grandis were simultaneously extracted at 98% extraction rates and simply separated at higher than 95% recovery rates. The method provides a simple and high-efficient extraction and separation of wide range bioactive substances.

  20. 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


    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)

  1. Sensitive high-performance liquid chromatographic quantitation of gabapentin in human serum using liquid-liquid extraction and pre-column derivatization with 9-fluorenylmethyl chloroformate. (United States)

    Bahrami, Gholamreza; Kiani, Amir


    Most of the published methods for analysis of gabapentin, an antiepileptic agent, in human serum are based on the same approach, involving o-phthaldialdehyde derivatization of deproteinized serum samples. The present paper however, describes a new, simple and sensitive high-performance liquid chromatographic method for determination of gabapentin in human serum using liquid-liquid extraction and 9-fluorenylmethyl chloroformate (FMOC-Cl) as pre-column labeling agent. The drug and an internal standard (azithromycin) were extracted from serum by salting-out approach using a mixture of dichloromethane-2 propanol (1:1, v/v) as the extracting solvent. The extracted analytes were subjected to derivatization with FMOC-Cl in the presence of phosphate buffer (pH 7). A mobile phase consisting of methanol-0.05 M sodium phosphate buffer (73/27, v/v; pH of 3.9) containing 1 ml/l triethylamine was eluted and chromatographic separation was performed on a Shimpack CLC-C18 (150 mm x 4.6 mm) column. The standard curve was linear over the range of 0.03-20 microg/ml and limit of quantification was 0.03 microg/ml. The performance of analysis was studied and the validated method showed excellent performance in terms of selectivity, specificity, sensitivity, precision and accuracy. No interferences were found from commonly co-administered antiepileptic agents.

  2. High-performance liquid chromatographic determination of polyamines in milk as their 9-fluorenylmethoxycarbonyl derivatives using a column-switching technique. (United States)

    Bellagamba, F; Moretti, V M; Mentasti, T; Albertini, A; Luzzana, U; Valfrè, F


    A high-performance liquid chromatographic method for the determination of polyamines in milk is milk is described. Polyamines were extracted in perchloric acid and derivatized with 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl). The excess of reagent was reacted with aspartic acid before the analysis on a column-switching system. Linearity of derivatization was calculated for each amine and the coefficient of regression ranged from 0.994 to 0.999. Chromatographic separation of FMOC-polyamines was achieved with a gradient elution programme of water-acetonitrile. The correlation coefficients of the standard curves in the concentration range from 0.5 to 5 nmol ml-1 were higher than 0.991. The repeatability of the method, expressed as R.S.D. for each polyamines ranged from 3.0 to 8.6%. The percent mean recoveries at 1 nmol ml-1 spiking level were 49 +/- 3, 58 +/- 5, 61 +/- 5 and 48 +/- 4 for putrescine, cadaverine, spermidine and spermine, respectively. The limit of detection, calculated on the basis of three times signal-to-noise ratio, was 50 pmol ml-1 for each polyamine.

  3. Development and validation of a rapid column-switching high-performance liquid chromatographic method for the determination of Lamotrigine in human serum. (United States)

    Brunetto, María del Rosario; Contreras, Yaritza; Delgado, Yelitza; Gallignani, Máximo; Estela, José Manuel; Martin, Víctor Cerdà


    This study describes a simple and sensitive column-switching high-performance liquid chromatographic method with UV detection for the determination of Lamotrigine in 50 microL of serum. After solid-phase extraction of Lamotrigine on an Oasis HLB extraction precolumn (20 x 3.9 mm; dp: 25 microm), chromatographic separation was achieved at 30 degrees C on a Chromolith RP-18e column (50 mm x 4.6 mm i.d.) using a solution of 20% acetonitrile in 15 mM phosphate buffer (pH 7.0) as the mobile phase, at a flow-rate of 2.0 mL/min. The eluant was detected at 215 nm. The retention time for Lamotrigine was 1.28 min. The total analysis time was ca. 5 min. However, the overlap of sample preparation, analysis, and reconditioning of the precolumn increased the overall sample throughput to one injection every 3 min. The method was validated for system suitability, linearity, precision, accuracy, robustness, and limit of quantitation. The linearity of the calibration lines, expressed by the linear correlation coefficient, was better than 0.9996. Recovery studies achieved from Lamotrigine spiked plasma samples showed values greater than 93%, demonstrating the excellent extraction efficiency of the precolumn. Intra- and inter-day precision were generally acceptable; the coefficient of variation was < 2.3% in all cases. The detection limits for Lamotrigine at a signal-to-noise ratio of 3 was 0.002 microg/mL when a sample volume of 50 microL was injected. However, it was possible to enhance the sensitivity further by injecting larger volumes, up to 200 microL. The method was shown to be robust and the results were within the acceptable range. The method was successfully applied to the determination of Lamotrigine in human serum samples of patients submitted to Lamotrigine therapy.

  4. Determination of marker pteridins and biopterin reduced forms, tetrahydrobiopterin and dihydrobiopterin, in human urine, using a post-column photoinduced fluorescence liquid chromatographic derivatization method

    Energy Technology Data Exchange (ETDEWEB)

    Canada-Canada, Florentina, E-mail: [Department of Analytical Chemistry, University of Extremadura, 06071 Badajoz (Spain); Espinosa-Mansilla, Anunciacion; Munoz de la Pena, Arsenio; Mancha de Llanos, Alicia [Department of Analytical Chemistry, University of Extremadura, 06071 Badajoz (Spain)


    A liquid chromatographic method for the simultaneous analysis of marker pteridins and biopterin reduced forms, in urine samples is proposed. A Zorbax Eclipse XDB-C18 column was used for the chromatographic separation, using a 98/2 (v/v), citrate buffer (pH 5.5)-acetonitrile mobile phase, in isocratic mode. A post-column photoderivatization was carried out with an on-line photoreactor, located between a diode array detector (DAD) and a fast scanning fluorescence detector (FSFD). Neopterin (NEO), biopterin (BIO), pterin (PT) and dihydrobiopterin (BH2) were determined by measuring native fluorescence, using the photoreactor in OFF-mode, and tetrahydrobiopterin (BH4) was determined by measuring of the induced fluorescence of the generated photoproducts, using the photoreactor in ON-mode. In addition, Creatinine (CREA), as a reference of metabolites excrection in urine, was simultaneously determined using the DAD detector. Detection limits were 0.2, 13.0, 0.3, 0.3 and 3.5 ng mL{sup -1}, for NEO, BH2, BIO, PT and BH4, respectively, and 0.4 {mu}g mL{sup -1} for CREA. Ratio values for NEO/CREA, PT/CREA, BH4/CREA, BH2/CREA, NEO/BIO and BIO{sub total}/CREA, in urine samples, of healthy children and adults, phenylketonuric children and infected mononucleosis children, are reported. A comparative study, about the mean values obtained for each of the compounds, by the present procedure and by the classical iodine oxidation method (Fukushimas method), has been performed, in urine samples belonging to healthy volunteers. The values obtained were BH4/CREA: 0.41, BH2/CREA: 0.31 and BIO{sub total}/CREA: 0.73, by the proposed method, and BH4/CREA: 0.35, BH2/CREA: 0.20 and BIO{sub total}/CREA: 0.48, by iodine oxidation method.

  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


    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. Development of an Exhaled Breath Monitoring System with Semiconductive Gas Sensors, a Gas Condenser Unit, and Gas Chromatograph Columns

    Directory of Open Access Journals (Sweden)

    Toshio Itoh


    Full Text Available Various volatile organic compounds (VOCs in breath exhaled by patients with lung cancer, healthy controls, and patients with lung cancer who underwent surgery for resection of cancer were analyzed by gas condenser-equipped gas chromatography-mass spectrometry (GC/MS for development of an exhaled breath monitoring prototype system involving metal oxide gas sensors, a gas condenser, and gas chromatography columns. The gas condenser-GC/MS analysis identified concentrations of 56 VOCs in the breath exhaled by the test population of 136 volunteers (107 patients with lung cancer and 29 controls, and selected four target VOCs, nonanal, acetoin, acetic acid, and propanoic acid, for use with the condenser, GC, and sensor-type prototype system. The prototype system analyzed exhaled breath samples from 101 volunteers (74 patients with lung cancer and 27 controls. The prototype system exhibited a level of performance similar to that of the gas condenser-GC/MS system for breath analysis.

  7. Development of an Exhaled Breath Monitoring System with Semiconductive Gas Sensors, a Gas Condenser Unit, and Gas Chromatograph Columns. (United States)

    Itoh, Toshio; Miwa, Toshio; Tsuruta, Akihiro; Akamatsu, Takafumi; Izu, Noriya; Shin, Woosuck; Park, Jangchul; Hida, Toyoaki; Eda, Takeshi; Setoguchi, Yasuhiro


    Various volatile organic compounds (VOCs) in breath exhaled by patients with lung cancer, healthy controls, and patients with lung cancer who underwent surgery for resection of cancer were analyzed by gas condenser-equipped gas chromatography-mass spectrometry (GC/MS) for development of an exhaled breath monitoring prototype system involving metal oxide gas sensors, a gas condenser, and gas chromatography columns. The gas condenser-GC/MS analysis identified concentrations of 56 VOCs in the breath exhaled by the test population of 136 volunteers (107 patients with lung cancer and 29 controls), and selected four target VOCs, nonanal, acetoin, acetic acid, and propanoic acid, for use with the condenser, GC, and sensor-type prototype system. The prototype system analyzed exhaled breath samples from 101 volunteers (74 patients with lung cancer and 27 controls). The prototype system exhibited a level of performance similar to that of the gas condenser-GC/MS system for breath analysis.

  8. Gas chromatographic-mass spectrometric analysis of acrylamide and acetamide in cigarette mainstream smoke after on-column injection. (United States)

    Diekmann, Joerg; Wittig, Arno; Stabbert, Regina


    A method is described for the simultaneous determination of two short-chained amides, acrylamide and acetamide (classified by the International Agency for Research on Cancer as probable and possible human carcinogens, respectively), in total particulate matter using gas chromatography-on-column injection and mass spectrometric detection. Sample preparation is kept to a minimum, and the proposed analytical procedure proves to be fast, sensitive, and precise. Validation studies show good linearity with a regression coefficient of r2=.000 for both compounds. Quantitation limits are 32 ng/mL for acrylamide and 70 ng/mL for acetamide. In the particulate phase of mainstream smoke from the University of Kentucky Reference Cigarette 2R4F, 2.3 microg/cig acrylamide and 4.7 microg/cig acetamide are found; no acetamide and only .0074 microg/cig acrylamide is found in the gas phase. Possible mechanisms of formation in cigarette smoke are discussed.

  9. Preperation and performance of {sup 99}Mo/{sup 99m}Tc chromatographic column generator based on zirconium molybdosilicate

    Energy Technology Data Exchange (ETDEWEB)

    Mostafa, M.; Saber, H.M.; El-Sadek, A.A. [Atomic Energy Authority, Cairo (Egypt). Hot Labs. Center; Nassar, M.Y. [Benha Univ. (Egypt). Chemistry Dept.


    Zirconium molybdosilicate (ZrMoSi) gel prepared using {sup 99}Mo radiotracer via peroxo route was used as a base material for {sup 99}Mo/{sup 99m}Tc column generator. The {sup 99m}Tc elution yield and {sup 99}Mo breakthrough in the eluate were studied as a function of the pH-value of gel precipitation, gel drying temperature and Zr: Mo: Si molar ratio. Precipitation pH-value of 2, drying temperature of 100 C and Zr: Mo: Si molar ratio of 0.5: 0.5: 1 were found to be the optimum conditions achieving {sup 99m}Tc elution yield of 82% and {sup 99}Mo breakthrough of 1.0 x 10{sup -3}%. The gel prepared with the optimum conditions was characterized by BET surface area and pore size analyzer, IR spectroscopy, thermal analysis (TGA and DTA), XRD, XRF and FESEM. Technetium-99m eluted from the optimum ZrMoSi {sup 99}Mo/{sup 99m}Tc generator was found to have a high radiochemical purity (98% as {sup 99m}TcO{sub 4}{sup -}) and chemical purity meeting criteria of clinical grade.

  10. Ion chromatographic method for the simultaneous determination of nitrite and nitrate by post-column indirect fluorescence detection. (United States)

    Stalikas, Constantine D; Konidari, Constantina N; Nanos, Christos G


    This short paper highlights the suitability of ion chromatography with post-column indirect fluorescence detection to determine simultaneously nitrite and nitrate based on the quenching of tryptophan native fluorescence. The method uses an enhanced fluorescence mobile phase containing tryptophan and detects the suppression of fluorescence of the mobile phase due to the elution of the target ions. The phenomenon of fluorescence quenching of tryptophan is highly induced by the presence of phosphate ions. The quenched fluorescence intensity exhibits concentration dependence in the range 1-25 mg/l and 3-65 mg/l for nitrite and nitrate, respectively. The relative standard deviation for five replicates of a standard solution containing a mixture of 5 mg/l of nitrite and 10 mg/l of nitrate lies around 2.8%. This simple coupling technique results in a relatively sensitive, fast, and accurate method, allowing for both qualitative and quantitative analysis of nitrite and nitrate. The method can easily be implemented to real samples such as foodstuffs, fertilizers and soils and is proven to be precise and accurate when compared with reference methods.

  11. On-line coupling of an ion chromatograph to the ICP-MS: Separations with a cation exchange chromatography column

    Energy Technology Data Exchange (ETDEWEB)

    Roellin, Stefan [Studsvik Nuclear AB, Nykoeping (Sweden)


    An ion chromatography system was coupled on-line to the ICP-MS. All separations were made with a cation exchange chromatography column. Fundamental laws about elution parameters affecting individual retention times and elution forms are explained by applying a proper ion exchange mechanism for the isocratic elution (separations with constant eluent concentration) of mono-, di-, tri-, and tetravalent cations and the actinide species MO{sub 2}{sup +} and MO{sub 2}{sup 2+}. A separation method with two eluents has been investigated to separate mono- from divalent ions in order to separate isobaric overlaps of Rb/Sr and Cs/Ba. The ions normally formed by actinides in aqueous solutions in the oxidation states III to VI are M{sup 3+}, M{sup 4+}, MO{sub 2}{sup +} and MO{sub 2}{sup 2+} respectively. Elution parameters were investigated to separate all four actinide species from each other in order to separate isobaric overlaps of the actinides Np, Pu, U and Am. A major question of concern over the possible release of actinides to the environment is the speciation of actinides within their four possible oxidation states. To check the possibility of speciation analysis with ion chromatography, a separation method was investigated to separate U{sup 4+} and UO{sub 2}{sup 2+} without changing the redox species composition during the separation. First results of Pu speciation analysis showed that Pu could be eluted as three different species. Pu(VI) was always eluting at the same time as Np(V). This was surprising as Pu(VI) is expected to have the same chemical characteristics as U(VI) and thus was expected to elute at the same time as U(VI)

  12. Development and validation of a reversed-phase column liquid chromatographic method for the determination of five cephalosporins in pharmaceutical preparations. (United States)

    Elkady, Ehab F; Abbas, Samah S


    A new, simple, rapid, and precise RP-HPLC method has been developed and validated for the determination of five cephalosporins, namely, cefalexin, cefoperazone, ceftriaxone, ceftazidime, and cefepime. The method has been applied successfully for simultaneous determination of cefalexin in a binary mixture with sodium benzoate in a suspension, and cefoperazone in a binary mixture with sulbactam in vials. Chromatographic separation was achieved on a Waters microBondapak C18 column (250 x 4.6 mm id, 10 pm particle size) using the mobile phase monobasic potassium phosphate (50 mM, pH 4.6)-acetonitrile (80 + 20, v/v) with UV detection. A flow rate of 1 mL/min was applied. Linearity, accuracy, and precision were found to be acceptable over the concentration range of 30-300, 3-30, and 15-120 microg/mL for the studied cephalosporins, sodium benzoate, and sulbactam, respectively. The optimized method proved to be specific, robust, and accurate for QC of the cited drugs in their pharmaceutical preparations.

  13. 出口压减压下非极性薄涂气相色谱柱的特性及应用%Performance and Application of Decompression and Low Coated Non-polar Liquid Phases in Gas Chromatographic Column

    Institute of Scientific and Technical Information of China (English)

    袁晓燕; 陈贻文


    In this paper,performance of decompression and low coated gas chromatographic column of non-polar liquid phases is described. Chromatographic parameters of a column packed with 0.5% OV-101 on glazing support (φ0.18~0.25mm) 302 was studied for C、C7、C8、C9 n-alkanes samples. The results showed that the column pressure 0.068 MPa was best,the column temperature for n-octane could be decreased to 52°C,column efficiency was four time as high as ordinary pressure detection.%以甲基硅油0V-101、210为固定液,研究了出口压减压下薄涂气相色谱柱的特性,从柱压、柱温、保留值、柱效、柱的稳定性等方面进行了探讨。应用于烷烃及几种农药的分离,效果良好。

  14. Preparation of bovine serum albumin biological chromatographic column and its application in determination of Aspirin%牛血清白蛋白色谱柱的制备及对阿司匹林的含量测定

    Institute of Scientific and Technical Information of China (English)

    唐玲利; 韦室百; 黄东萍; 黄明立; 阮冲


    Objective To prepare biological chromatographic column to separate and determine the ingredients of drugs. Methods Silica gel was reacted with 3-aminopropyl trimethoxylsilane to form amine functionalized activated sil-ica gel, which was covalent binding with BSA to synthesize BSA bonded stationary phase. Then BSA bonded stationary phase was packed column with homogenization, thus BSA biological chromatographic column was prepared. Aspirin was taken as a detective object to examine the combination performance and separation performance of BSA bonded sta-tionary phase. Results It came to that, the combined rate was 3.69 μmol/g, the biological chromatographic column was 74 mg/g, the amount of Aspirin in per tablet was 14.65 μg and the labeled amount was 107.8% detected by BSA bio-logical chromatographic column. Conclusion All of above shows that BSA bonded stationary phase is synthesized suc-cessfully, and the BSA biological chromatographic column has good combination property and separation property.%目的:制备生物色谱柱,用于分离或测定药物成分。方法采用3-氨基丙基三甲氧基硅烷(APTS)与硅胶反应生成氨基功能化的活化硅胶,并与牛血清蛋白(BSA)共价结合形成BSA键合固定相,匀浆装柱制备成BSA生物色谱柱,以阿司匹林(Aspirin,ASP)为分析对象考察BSA固定相的结合性能和分离性能。结果 BSA结合率为3.69μmol/g,ASP在BSA键合固定相色谱柱上的最大结合量为74 mg/g,经BSA色谱柱测得阿司匹林肠溶片的含量为14.65μg/片,标示量为107.8%。结论这表明BSA与硅胶载体成功结合形成BSA键合固定相,所制备的BSA生物色谱柱具有良好的结合性能与分离性能。

  15. Validated stability indicating liquid chromatographic determination of ebastine in pharmaceuticals after pre column derivatization: Application to tablets and content uniformity testing

    Directory of Open Access Journals (Sweden)

    Eid Manal


    Full Text Available Abstract An accurate, simple, sensitive and selective reversed phase liquid chromatographic method has been developed for the determination of ebastine in its pharmaceutical preparations. The proposed method depends on the complexation ability of the studied drug with Zn2+ ions. Reversed phase chromatography was conducted using an ODS C18 (150 × 4.6 mm id stainless steel column at ambient temperature with UV-detection at 260 nm. A mobile phase containing 0.025%w/v Zn2+ in a mixture of (acetonitril/methanol; 1/4 and Britton Robinson buffer (65:35, v/v adjusted to pH 4.2, has been used for the determination of ebastine at a flow rate of 1 ml/min. The calibration curve was rectilinear over the concentration range of 0.3 - 6.0 μg/ml with a detection limit (LOD of 0.13 μg/ml, and quantification limit (LOQ of 0.26 μg/ml. The proposed method was successfully applied for the analysis of ebastine in its dosage forms, the obtained results were favorably compared with those obtained by a comparison method. Furthermore, content uniformity testing of the studied pharmaceutical formulations was also conducted. The composition of the complex as well as its stability constant was also investigated. Moreover, the proposed method was found to be a stability indicating one and was utilized to investigate the kinetics of alkaline and ultraviolet induced degradation of the drug. The first-order rate constant and half life of the degradation products were calculated.

  16. HPLC柱效对检测水中磺胺二甲基嘧啶色谱条件的影响%HPLC Column Efifciency Inlfuences on Chromatographic Conditions for Detection of Sulfamethazine in Water

    Institute of Scientific and Technical Information of China (English)

    杨娜; 万俊锋; 王岩; 李红丽


    When column efficiency decreased, the influence of chromatographic condition for determination of sulfamethazine in water was studied. Compared the old and new chromatographic of column separation effect, symmetry and the peak area of chromatographic peak, the results showed that the old chromatographic column efficiency was reduced, the separation effect of the target was poorer, the target of the absorption peak area was smaller, peak shape was asymmetric. The symmetry of peak shape and seperation effect were improved as 0.125% ice acetic acid add into the mobile phase water to adjust pH value of 4.5.%研究色谱柱的柱效降低后对高效液相色谱测定水中磺胺二甲基嘧啶色谱条件的影响.比较了新旧色谱柱的分离效果、色谱峰的对称性和峰面积,结果表明,旧色谱柱的柱效降低,对目标物的分离效果变差,目标物的吸收峰面积变小,峰形不对称.对色谱条件进行了优化试验,结果表明,对流动相水相添加0.125%的冰乙酸调节pH值为4.5后色谱峰的峰形对称性和分离效果得到改善.

  17. Liquid-chromatographic separation and determination of process-related impurities, including a regio-specific isomer of celecoxib on reversed-phase C18 column dynamically coated with hexamethyldisilazane. (United States)

    Rao, R Nageswara; Meena, S; Nagaraju, D; Rao, A Raghuram; Ravikanth, S


    A simple and rapid reversed-phase high-performance liquid-chromatographic method for the separation and determination of process-related impurities of celecoxib (CXB) in bulk drugs and pharmaceuticals was developed. The separation of impurities viz., 4-methylacetophenone (I), 1-(4-methylphenyl)-4,4,4-trifluorobutane-1,3-dione (II), 4-hydrazinobenzene sulfonamide (III) and a regio-specific isomer [3-(4-methylphenyl)-5-trifluoromethyl-1H-pyrazole-1-yl]-benzenesulfonamide (IV), was accomplished on an Inertsil ODS-3 column dynamically coated with 0.1% hexamethyldisilazane (HMDS) in acetonitrile:water (55:45 v/v) as a mobile phase and detection at 242 nm using PDA at ambient temperature. The chromatographic conditions were optimized by studying the effects of HMDS, an organic modifier, time of silanization and column temperature. The method was validated and found to be suitable not only for monitoring the synthetic reactions, but also to evaluate the quality of CXB.

  18. Chromatographic selectivity of poly(alkyl methacrylate-co-divinylbenzene) monolithic columns for polar aromatic compounds by pressure-driven capillary liquid chromatography. (United States)

    Lin, Shu-Ling; Wang, Chih-Chieh; Fuh, Ming-Ren


    In this study, divinylbenzene (DVB) was used as the cross-linker to prepare alkyl methacrylate (AlMA) monoliths for incorporating π-π interactions between the aromatic analytes and AlMA-DVB monolithic stationary phases in capillary LC analysis. Various AlMA/DVB ratios were investigated to prepare a series of 30% AlMA-DVB monolithic stationary phases in fused-silica capillaries (250-μm i.d.). The physical properties (such as porosity, permeability, and column efficiency) of the synthesized AlMA-DVB monolithic columns were investigated for characterization. Isocratic elution of phenol derivatives was first employed to evaluate the suitability of the prepared AlMA-DVB columns for small molecule separation. The run-to-run (0.16-1.20%, RSD; n = 3) and column-to-column (0.26-2.95%, RSD; n = 3) repeatabilities on retention times were also examined using the selected AlMA-DVB monolithic columns. The π-π interactions between the aromatic ring and the DVB-based stationary phase offered better recognition on polar analytes with aromatic moieties, which resulted in better separation resolution of aromatic analytes on the AlMA-DVB monolithic columns. In order to demonstrate the capability of potential environmental and/or food safety applications, eight phenylurea herbicides with single benzene ring and seven sulfonamide antibiotics with polyaromatic moieties were analyzed using the selected AlMA-DVB monolithic columns.

  19. Column Liquid Chromatography. (United States)

    Majors, Ronald E.; And Others


    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  20. Liquid-chromatographic assay of urinary vanillylmandelic acid and homovanillic acid, with clean-up by on-column injection of acetonitrile or methanol. (United States)

    Kodama, K; Yamanaka, K; Nakata, T; Aoyama, M


    To separately measure vanillylmandelic acid (VMA) and homovanillic acid (HVA) in urine, the sample is diluted 10-fold with 50 mmol/L phosphoric acid, then exactly 5 microL is injected directly onto a 50 X 4.6 mm column of Nucleosil 3C18. Samples can be injected at 5-min intervals because all peaks after these compounds of interest are washed away. VMA is eluted from the column after 2.8 min with 50 mmol/L phosphate buffer, pH 2.2, and measured by electrochemical detection. All peaks eluting after VMA are washed away together, by injection of 50 microL of acetonitrile onto the column. HVA is eluted from the column after 3.3 min with a 100/10 (by vol) mixture of the phosphate buffer and acetonitrile. All later-eluting peaks are washed away together, by injection of 50 microL of methanol onto the column. Analytical recoveries of VMA and HVA were 98.5% and 100.6%, respectively; the CVs for various concentrations of either in urine were about 3%.

  1. 气相色谱质谱联用仪一机多用的改进%Simultaneousl application of dual-column and dual detectors on chromatograph-mass spectrometry-FID system

    Institute of Scientific and Technical Information of China (English)



    应用双进样口、双毛细管色谱柱以及质谱检测器(M SD )和氢火焰检测器(FID ),通过四通分流装置在一台带FID的气相色谱质谱联用仪(GCMS)上面实现一根毛细管柱同时采集MSD和FID双检测器信号数据;同时安装两根不同极性的柱子,不需要拆装柱子,进行无痕切换使用来满足不同样品分析要求。%This paper introduces the mathod of MSD and FID simultaneous detection in 6890N/5975C gas chromatograph-mass spectrometer and the mathod can meet different analysis without column ex-change .

  2. Automated column liquid chromatographic determination of amoxicillin and cefadroxil in bovine serum and muscle tissue using on-line dialysis for sample preparation

    NARCIS (Netherlands)

    Snippe, N; van de Merbel, N C; Ruiter, F P; Steijger, O M; Lingeman, H; Brinkman, U A


    A fully automated method is described for the determination of amoxicillin and cefadroxil in bovine serum and muscle tissue. The method is based on the on-line combination of dialysis and solid-phase extraction for sample preparation, and column liquid chromatography with ultraviolet detection. In o

  3. Effect of monomer mixture composition on structure and chromatographic properties of poly(divinylbenzene-co-ethylvinylbenzene-co-2-hydroxyethyl methacrylate) monolithic rod columns for separation of small molecules. (United States)

    Smirnov, Konstantin N; Dyatchkov, Ivan A; Telnov, Maxim V; Pirogov, Andrey V; Shpigun, Oleg A


    Porous poly(divinylbenzene-co-ethylvinylbenzene-co-2-hydroxyethyl methacrylate) monoliths were synthesized via thermally initiated free-radical polymerization in confines of surface-vinylized glass columns (150 mm × 3 mm i.d.) and applied to the reversed-phase separation of low-molecular-weight aromatic compounds. In order to compensate for the polymer shrinkage during the synthesis and prevent the monolith from detachment from the column wall, polymerization was conducted under nitrogen pressure. The reaction proceeded at 60°C for 22 h. 2,2'-Azo-bis-isobutironitrile was used as the initiator and 1-dodecanol was used as the porogen. A series of monoliths with different monomer ratios were obtained. All the monoliths had high specific surface areas ranging from 370 to 490 m(2)/g. In the studied range of monomer mixture compositions, the mechanical stability of the stationary phase in water/acetonitrile eluents was found to be high enough and practically insensitive to the fraction of 2-hydroxyethyl methacrylate (HEMA). Increasing the molar fraction of HEMA from 10.5% to 14.7% resulted in the decrease of column permeability by two orders of magnitude (from 1.1×10(-12) to 1.8×10(-14) m(2)) and led to weaker retention of alkylbenzenes. The higher HEMA content was shown to reduce the plate height of the columns in the separation of small molecules from 160-490 μm to 40-76 μm. This was attributed mainly to the decrease of the domain size of the monoliths leading to lower eddy dispersion and mass transfer resistance in the column.

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


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


    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...

  5. Simultaneous spectrophotometric determination of phosphate and silicate ions in river water by using ion-exclusion chromatographic separation and post-column derivatization. (United States)

    Nakatani, Nobutake; Kozaki, Daisuke; Masuda, Wakako; Nakagoshi, Nobukazu; Hasebe, Kiyoshi; Mori, Masanobu; Tanaka, Kazuhiko


    The simultaneous spectrophotometric determination of phosphate and silicate ions in river water was examined by using ion-exclusion chromatography and post-column derivatization. Phosphate and silicate ions were separated by the ion-exclusion column packed with a polymethacrylate-based weakly acidic cation-exchange resin in the H(+)-form (TSKgel Super IC-A/C) by using ultra pure water as an eluent. After the post-column derivatization with molybdate and ascorbic acid, so-called molybdenum-blue, both ions were determined simultaneously by spectrophotometry. The effects of sulfuric acid, sodium molybdate and ascorbic acid concentrations and reaction coil length, which have relation to form the reduced complexes of molybdate and ions, on the detector response for phosphate and silicate ions were investigated. Under the optimized conditions (color-forming reactant, 50 mM sulfuric acid-10 mM sodium molybdate; reducing agent, 50 mM ascorbic acid; reaction coil length, 6 m), the calibration curves of phosphate and silicate ions were linear in the range of 50-2000 microg L(-1) as P and 250-10,000 microg L(-1) as Si. This method was successfully applied to water quality monitoring of Kurose-river watershed and it suggested that the effluent from a biological sewage treatment plant was significant source of phosphate ion in Kurose-river water.

  6. Monolithic silica spin column extraction and simultaneous derivatization of amphetamines and 3,4-methylenedioxyamphetamines in human urine for gas chromatographic-mass spectrometric detection. (United States)

    Nakamoto, Akihiro; Nishida, Manami; Saito, Takeshi; Kishiyama, Izumi; Miyazaki, Shota; Murakami, Katsunori; Nagao, Masataka; Namura, Akira


    A simple, sensitive, and specific method with gas chromatography-mass spectrometry was developed for simultaneous extraction and derivatization of amphetamines (APs) and 3,4-methylenedioxyamphetamines (MDAs) in human urine by using a monolithic silica spin column. All the procedures, such as sample loading, washing, and elution were performed by centrifugation. APs and MDAs in urine were adsorbed on the monolithic silica and derivatized with propyl chloroformate in the column. Methamphetamine-d(5) was used as an internal standard. The linear ranges were 0.01-5.0 microg mL(-1) for methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA) and 0.02-5.0 microg mL(-1) for amphetamine (AP) and 3,4-methylenedioxyamphetamine (MDA) (coefficient of correlation > or = 0.995). The recovery of APs and MDAs in urine was 84-94%, and the relative standard deviation of the intra- and interday reproducibility for urine samples containing 0.1, 1.0, and 4.0 microg mL(-1) of APs and MDAs ranged from 1.4% to 13.6%. The lowest detection limit (signal-to-noise ratio > or = 3) in urine was 5 ng mL(-1) for MA and MDMA and 10 ng mL(-1) for AP and MDA. The proposed method can be used to perform simultaneous extraction and derivatization on spin columns that have been loaded with a small quantity of solvent by using centrifugation.

  7. Monolithic silica spin column extraction and simultaneous derivatization of amphetamines and 3,4-methylenedioxyamphetamines in human urine for gas chromatographic-mass spectrometric detection

    Energy Technology Data Exchange (ETDEWEB)

    Nakamoto, Akihiro [Scientific Investigation Laboratory, Hiroshima Prefectural Police Headquarters, Kohnan 2-26-3, Naka-ku, Hiroshima 730-0825 (Japan); Nishida, Manami [Hiroshima University Technical Center, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551 (Japan); Saito, Takeshi [Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Shimokasuya 143, Isehara, Kanagawa 259-1143 (Japan); Kishiyama, Izumi; Miyazaki, Shota [GL Sciences Inc., Sayamagahara 237-2, Iruma, Saitama 358-0032 (Japan); Murakami, Katsunori [Scientific Investigation Laboratory, Hiroshima Prefectural Police Headquarters, Kohnan 2-26-3, Naka-ku, Hiroshima 730-0825 (Japan); Nagao, Masataka [Department of Forensic Medicine, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551 (Japan); Namura, Akira, E-mail: [Department of Forensic Medicine, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551 (Japan)


    A simple, sensitive, and specific method with gas chromatography-mass spectrometry was developed for simultaneous extraction and derivatization of amphetamines (APs) and 3,4-methylenedioxyamphetamines (MDAs) in human urine by using a monolithic silica spin column. All the procedures, such as sample loading, washing, and elution were performed by centrifugation. APs and MDAs in urine were adsorbed on the monolithic silica and derivatized with propyl chloroformate in the column. Methamphetamine-d{sub 5} was used as an internal standard. The linear ranges were 0.01-5.0 {mu}g mL{sup -1} for methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA) and 0.02-5.0 {mu}g mL{sup -1} for amphetamine (AP) and 3,4-methylenedioxyamphetamine (MDA) (coefficient of correlation {>=}0.995). The recovery of APs and MDAs in urine was 84-94%, and the relative standard deviation of the intra- and interday reproducibility for urine samples containing 0.1, 1.0, and 4.0 {mu}g mL{sup -1} of APs and MDAs ranged from 1.4% to 13.6%. The lowest detection limit (signal-to-noise ratio {>=} 3) in urine was 5 ng mL{sup -1} for MA and MDMA and 10 ng mL{sup -1} for AP and MDA. The proposed method can be used to perform simultaneous extraction and derivatization on spin columns that have been loaded with a small quantity of solvent by using centrifugation.

  8. High-performance liquid chromatographic assay for catecholamines and metanephrines using fluorimetric detection with pre-column 9-fluorenylmethyloxycarbonyl chloride derivatization. (United States)

    Chan, E C; Wee, P Y; Ho, P Y; Ho, P C


    A convenient HPLC-fluorescent assay of norepinephrine (NE), epinephrine (E), dopamine (DA) and their 3-O-methylated metabolites, normetanephrine (NM) and metanephrine (MN) was developed. These analytes were coupled to 9-fluorenylmethyloxycarbonyl chloride (FMOC-Cl) before assays. Results showed that using a linear gradient elution, peaks of FMOC-NE, FMOC-E, FMOC-DA, FMOC-NM, FMOC-MN and FMOC-DHBA (3,4-dihydroxybenzylamine, internal standard) were simultaneously resolved within 40 min. Optimization of the chromatographic and derivatization conditions, and validation of the assay were further discussed in the paper. The structures of these derivatives were confirmed by atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The molecular ions [M+H]- of FMOC-NE, FMOC-E, FMOC-DA, FMOC-NM and FMOC-MN were m/z 836, 850, 820, 628 and 642, respectively. Based on these findings, the FMOC-derivatives of metanephrines and catecholamines were confirmed to be bi-substituted and tri-substituted respectively at the amino and catechol functional groups. Finally, the assay was successfully applied to the measurement of urinary E, DA, NM and MN after direct derivatization and simple cleaning.

  9. Effect of the silanization conditions on chromatographic behavior of an open-tubular capillary column coated with a modified silica-gel thin layer. (United States)

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


    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.

  10. High-performance liquid chromatographic separations of stereoisomers of chiral basic agrochemicals with polysaccharide-based chiral columns and polar organic mobile phases. (United States)

    Matarashvili, Iza; Shvangiradze, Iamze; Chankvetadze, Lali; Sidamonidze, Shota; Takaishvili, Nino; Farkas, Tivadar; Chankvetadze, Bezhan


    The separation of the stereoisomers of 23 chiral basic agrochemicals was studied on six different polysaccharide-based chiral columns in high-performance liquid chromatography with various polar organic mobile phases. Along with the successful separation of analyte stereoisomers, emphasis was placed on the effect of the chiral selector and mobile phase composition on the elution order of stereoisomers. The interesting phenomenon of reversal of enantiomer/stereoisomer elution order function of the polysaccharide backbone (cellulose or amylose), type of derivative (carbamate or benzoate), nature, and position of the substituent(s) in the phenylcarbamate moiety (methyl or chloro) and the nature of the mobile phase was observed. For several of the analytes containing two chiral centers all four stereoisomers were resolved with at least one chiral selector/mobile phase combination.

  11. Appraisal of four pre-column derivatization methods for the high-performance liquid chromatographic determination of free amino acids in biological materials. (United States)

    Fürst, P; Pollack, L; Graser, T A; Godel, H; Stehle, P


    Reversed-phase high-performance liquid chromatography (RP-HPLC) is a powerful method for assaying physiological amino acid concentrations in biological fluids. Four pre-column derivatization methods, with o-phthaldialdehyde (OPA), 9-fluorenylmethyl chloroformate (FMOC-Cl), phenyl isothiocyanate (PITC) and 1-dimethylaminonaphthalene-5-sulphonyl chloride (dansyl-Cl), were assessed with respect to their applicability in biological research. The methods permit the measurement of 21-26 major amino acids in 13-40 min. The superior sensitivity favours the use of OPA, FMOC-Cl and dansyl-Cl techniques. Because of instability of the OPA adducts, automated on-line derivatization is required when using this method in general practice. Application of the PITC method, although less sensitive, is useful in clinical chemistry, where sample availability is rarely a problem. Cystine determination is not feasible when using OPA or FMOC-Cl and with PITC the reproducibility and linearity are poor, whereas the dansyl-Cl method allows reliable quantitation. The four methods are currently used to perform ca. 8000 OPA and 5000-6000 FMOC-Cl, PITC and dansyl-Cl analyses of biological samples per year. The results obtained with the RP-HPLC methods compare favourably with those derived from conventional ion-exchange amino acid analyses. When the guard column is regularly changed after 120 analyses, the separation remains satisfactory for at least 700 OPA, 800 FMOC-Cl, 150 PITC and 500 dansyl-Cl analyses. Careful control of factors and limitations inherent in the various methodologies is a prerequesite for proper identification and appropriate quantitation.

  12. Spiral multicapillary columns (United States)

    Efimenko, A. P.; Naumenko, I. I.; Soboleva, V. K.


    It was shown in a theoretical study and confirmed by experiment that a spiral multicapillary column had maximum efficiency if the bunch of capillaries was additionally coiled around its longitudinal axis to produce an integral number of coils. This technique made it possible to manufacture gas-chromatographic columns with performance as high as 12 to 16 thousand theoretical plates. These columns can find various applications, especially if quick separation is required.

  13. Simultaneous determination of a ternary mixture of doxylamine succinate, pyridoxine hydrochloride, and folic acid by the ratio spectra-zero-crossing, double divisor-ratio spectra derivative, and column high-performance liquid chromatographic methods. (United States)

    Pathak, Ashutosh; Rajput, Sadhana J


    Three simple, rapid, and accurate methods, i.e., the derivative ratio spectra-zero-crossing method (method I), double divisor-ratio spectra derivative method (method II), and column reversed-phase high-performance liquid chromatographic (RP-HPLC) method (method III) were developed for the simultaneous determination of doxylamine succinate (DOX), pyridoxine hydrochloride (PYR), and folic acid (FA) in their ternary mixtures and in tablets. In methods I and II, the calibration graphs were linear in the range of 2.5-80, 1.0-40, and 1.0-30 microg/mL for DOX, PYR, and FA, respectively. In the HPLC method, the separation of these compounds was performed using mobile phase consisting of 0.05 M phosphate buffer (pH 6.3)-methanol-acetonitrile (50 + 20 + 30, v/v/v), and UV detection was performed at 263 nm. Linearity was observed between the concentrations of the analytes and peak areas [correlation coefficient (r) > or =0.9998] in the concentration range of 1.0-200, 4.0-600, and 4.0-600 microg/mL for DOX, PYR, and FA, respectively. The standard deviation of retention time in method III was 0.011, 0.015, and 0.016 for DOX, PYR, and FA, respectively. The precision studies for all of the methods gave relative standard deviation values of <2%. The results obtained from the methods were statistically compared by means of Student's t-test and the variance ratio F-test. It was concluded that all of the developed methods were equally accurate, sensitive, and precise. These methods could be applied to determine DOX, PYR, and FA in their combined dosage forms.

  14. Column chromatographic separation of polycyclic aromatic hydrocarbons in coal tar pitch and its GC/MS analysis%煤焦油沥青中多环芳烃的柱层析分离及其GC—MS分析

    Institute of Scientific and Technical Information of China (English)

    罗道成; 刘俊峰


    Coal tar pitch was extracted with isometric carbon disulfide - acetone mixed solvent under ultrasonic radiation and room temperature. Polycyclic aromatic hydrocarbons (PAHs) in coal tar pitch were extracted by mixed solvent. The extracts were absorbed by silica gel. The silica gel was eluted with petroleum ether, PAHs in coal tar pitch were separated by using column chromatographic method. A white crystal, a white powder and a colorless crystal (marked as M1, M2, M3 respectively) appeared in three eluents, and M1 ,M2 and M3 were analyzed with GC -MS respectively. The results showed that M1 was mainly composed of 3 - ring PAHs and heterocyclic compounds, M2 was mainly composed of 4 - ring PAHs and heterocyclic compounds, and Ms was composed of 4 - ring or 5 - ring PAHs.%室温下用等体积的二硫化碳-丙酮混合溶剂对煤焦油沥青进行超声辐射萃取,煤焦油沥青中多环芳烃(PAHs)被混合溶剂萃取,用硅胶吸附萃取物,以石油醚为洗脱液洗脱硅胶,采用柱层析法对煤焦油沥青中多环芳烃进行了分离.在定量收取的洗脱液中分别析出了白色晶体、白色粉状物质和无色晶体(分别标记为M1,M2,M3),用气相色谱-质谱联用仪(GC/MS)分别对M1,M2,M3进行了分析,结果表明,M1中主要为3个环的多环芳烃和杂环化合物,M2中主要为4个环的多环芳烃和杂环化合物,M3中全部为4~5个环的多环芳烃.

  15. Comparison of drug substance impurity profiles generated with extended length columns during packed-column SFC. (United States)

    Roston, D A; Ahmed, S; Williams, D; Catalano, T


    The current study assesses the effect of extending column length during gradient packed column sub/supercritical fluid chromatography (PCSFC) experiments on the detection of known and unknown impurities in a drug substance sample. Quantitative drug substance impurity profiles were generated and compared using multiple column PCSFC and HPLC conditions. Also, chromatographic figures of merit were estimated and compared for components of a standard mixture during PCSFC experiments, which used one column, four columns, and six columns in series.

  16. Analysis of phthalates in wine using liquid chromatography tandem mass spectrometry combined with a hold-back column: Chromatographic strategy to avoid the influence of pre-existing phthalate contamination in a liquid chromatography system. (United States)

    Hayasaka, Y


    This paper describes the development and application of a novel method for the analysis of phthalates in wine using HPLC-MS/MS combined with a hold-back column. Phthalates are ubiquitous contaminants in the environment and can be widely found in laboratory materials and equipment. A HPLC system is no exception and can be the source of contamination affecting the accuracy and precision of analytical results. The new method successfully separates phthalates from the different sources, a wine sample and HPLC system by a simple technique using an additional HPLC column (a hold-back column) placed upstream of the injection valve. The hold-back column effectively retains the HPLC-derived contaminants during column equilibrium time and delays their elution times from an analytical column. Consequently, a phthalate from a wine sample can be baseline separated as it elutes sufficiently earlier than the same phthalate from the HPLC system. HPLC-MS/MS analysis combined with the hold-back column demonstrated virtually no influence of the HPLC contaminants on the quantification of phthalates present in wine. Together with a simple and rapid sample preparation and the use of labeled internal standards, the method was confirmed to be robust and reliable to determine concentrations of phthalates in wine. Quantification limits were within the range of 1.6-9.8μgL(-1) for dimethyl, diethyl, dibutyl, benzylbutyl, bis(2-ethylhexyl) and dioctyl phthalates, and 7.5-26.6μgL(-1) for multiple isomeric phthalates, di-iso-nonyl and di-iso-dodecyl phthalates.

  17. Evaluation of glycidyl methacrylate-based monolith functionalized with weak anion exchange moiety inside 0.5 mm i.d. column for liquid chromatographic separation of DNA

    Directory of Open Access Journals (Sweden)

    Aprilia Nur Tasfiyati


    Full Text Available In this study, the organic polymer monolith was developed as a weak anion exchanger column in high performance liquid chromatography for DNA separation. Methacrylate-based monolithic column was prepared in microbore silicosteel column (100 × 0.5 mm i.d. by in-situ polymerization reaction using glycidyl methacrylate as monomer; ethylene dimethacrylate as crosslinker; 1-propanol, 1,4-butanediol, and water as porogenic solvents, with the presence of initiator α,α′-azobisisobutyronitrile (AIBN. The monolith matrix was modified with diethylamine to create weak anion exchanger via ring opening reaction of epoxy groups. The morphology of the monolithic column was studied by SEM. The properties of the monolithic column, such as permeability, mechanical stability, binding capacity and pore size distribution, were characterized in detail. From the results of the characterization, monoliths poly-(GMA-co-EDMA with total monomer percentage (%T 40 and crosslinker percentage (%C 25 was found to be the ideal composition of monomer and crosslinker. It has good mechanical stability and high permeability, adequate molecular recognition sites (represented with binding capacity value of 36 mg ml−1, and has relatively equal proportion of flow-through pore and mesopores (37.2% and 41.1% respectively. Poly-(GMA-co-EDMA with %T 40 and %C 25 can successfully separate oligo(dT12–18 and 50 bp DNA ladder with good resolution.

  18. The use of immunoaffinity columns connected in tandem for selective and cost-effective mycotoxin clean-up prior to multi-mycotoxin liquid chromatographic-tandem mass spectrometric analysis in food matrices. (United States)

    Wilcox, Joyce; Donnelly, Carol; Leeman, David; Marley, Elaine


    This paper describes the use of two immunoaffinity columns (IACs) coupled in tandem, providing selective clean-up, based on targeted mycotoxins known to co-occur in specific matrices. An IAC for aflatoxins+ochratoxin A+fumonisins (AOF) was combined with an IAC for deoxynivalenol+zearalenone+T-2/HT-2 toxins (DZT); an IAC for ochratoxin A (O) was combined with a DZT column; and an aflatoxin+ochratoxin (AO) column was combined with a DZT column. By combining pairs of columns it was demonstrated that specific clean-up can be achieved as required for different matrices. Samples of rye flour, maize, breakfast cereal and wholemeal bread were analysed for mycotoxins regulated in the EU, by spiking at levels close to EU limits for adult and infant foods. After IAC clean-up extracts were analysed by LC-MS/MS with quantification using multiple reaction monitoring. Recoveries were found to be in range from 60 to 108%, RSDs below 10% depending on the matrix and mycotoxin combination and LOQs ranged from 0.1n g/g for aflatoxin B1 to 13.0 ng/g for deoxynivalenol. Surplus cereal proficiency test materials (FAPAS(®)) were also analysed with found levels of mycotoxins falling within the satisfactory range of concentrations (Z score ≤ ± 2), demonstrating the accuracy of the proposed multi-mycotoxin IAC methods.

  19. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of semivolatile organic compounds in bottom sediment by solvent extraction, gel permeation chromatographic fractionation, and capillary-column gas chromatography/mass spectrometry (United States)

    Furlong, E.T.; Vaught, D.G.; Merten, L.M.; Foreman, W.T.; Gates, Paul M.


    A method for the determination of 79 semivolatile organic compounds (SOCs) and 4 surrogate compounds in soils and bottom sediment is described. The SOCs are extracted from bottom sediment by solvent extraction, followed by partial isolation using high-performance gel permeation chromatography (GPC). The SOCs then are qualitatively identified and quantitative concentrations determined by capillary-column gas chromatography/mass spectrometry (GC/MS). This method also is designed for an optional simultaneous isolation of polychlorinated biphenyls (PCBs) and organochlorine (OC) insecticides, including toxaphene. When OCs and PCBs are determined, an additional alumina- over-silica column chromatography step follows GPC cleanup, and quantitation is by dual capillary- column gas chromatography with electron-capture detection (GC/ECD). Bottom-sediment samples are centrifuged to remove excess water and extracted overnight with dichloromethane. The extract is concentrated, centrifuged, and then filtered through a 0.2-micrometer polytetrafluoro-ethylene syringe filter. Two aliquots of the sample extract then are quantitatively injected onto two polystyrene- divinylbenzene GPC columns connected in series. The SOCs are eluted with dichloromethane, a fraction containing the SOCs is collected, and some coextracted interferences, including elemental sulfur, are separated and discarded. The SOC-containing GPC fraction then is analyzed by GC/MS. When desired, a second aliquot from GPC is further processed for OCs and PCBs by combined alumina-over-silica column chromatography. The two fractions produced in this cleanup then are analyzed by GC/ECD. This report fully describes and is limited to the determination of SOCs by GC/MS.

  20. Tadpole toxicity prediction using chromatographic systems. (United States)

    Fernández-Pumarega, Alejandro; Amézqueta, Susana; Fuguet, Elisabet; Rosés, Martí


    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.

  1. Investigations into the chromatographic optimization of combined gas chromatographic/FTIR/MS (United States)

    Wulff, Ditmar


    Even with the explosive growth and acceptance of GC/MS it has some analytical limitations. Several of these deficiencies can be overcome with information provided by GC/FTIR. Combining a GC/MS and a GC/FTIR into one system provides economies of sample, time, space, and money as well as a higher confidence qualitative result. The later results from the ability of the mass spectro -meter to give molecular fragment information with strength in homolog identification while the infrared spectrometer gives class specific-functional group and geometrical isomer data. Several configurations of the combined light pipe GC/FTIR/MS are evaluated looking toward ease of use, information content, and data evaluation. The combined system's sensitivity, chromatographic integrity, and gas chromatographic column choices and their operational parameters are discussed. The series arrangement with the GC column effluent passing through the FTIR light pipe and then serially to the MS is compared to the post column split of the column effluent to the FTIR and MS as well as to the configuration using two GC columns. Operational recommendations are given to maximize chromatographic resolution, detector sensitivity, and sample throughput. Examples are shown illustrating the combined systems operation. All parameters discussed apply to work done on the HP 5890A GC, the HP5965A IRD, and the HP 5970B MSD.

  2. Gas chromatographic separation of hydrogen isotopes using metal hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Aldridge, F.T.


    A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60/sup 0/C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.

  3. Optimization and validation of a fast ultrahigh-pressure liquid chromatographic method for simultaneous determination of selected sulphonamides in water samples using a fully porous sub-2 μm column at elevated temperature. (United States)

    Shaaban, Heba; Górecki, Tadeusz


    High temperature in HPLC is considered a valuable tool helping to overcome the increase in the column backpressure when using small packing particles such as sub-2 μm, as it allows reduction in the mobile-phase viscosity. In this study, a fast analytical method based on HPLC-UV was developed using a sub-2 μm column at elevated temperature for the simultaneous determination of nine sulphonamides. Owing to the lower viscosity of the mobile phase, the separation could be achieved in 3 min at 60°C for all analytes. The effect of temperature, the organic modifier percentage and the flow rate on the retention time was studied. The method developed was used for the determination of selected sulphonamides in surface and wastewater samples. Sample preparation was carried out by solid-phase extraction on Oasis HLB cartridges. The method developed was validated based on the linearity, precision, accuracy, detection and quantification limits. The recovery ranged from 70.6 to 96 % with standard deviations not higher than 4.7%, except for sulphanilamide. Limits of detection ranged from 1 to 10 μg/L after optimization of all analytical steps. This method has the highest performance in terms of analytical speed compared with other published HPLC-UV methods for the determination of sulphonamides in water.

  4. Ion-exclusion chromatographic behavior of aliphatic carboxylic acids and benzenecarboxylic acids on a sulfonated styrene--divinylbenzene co-polymer resin column with sulfuric acid containing various alcohols as eluent. (United States)

    Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi


    The addition of C1-C7 alcohols (methanol, ethanol, propanol, butanol, heptanol, hexanol and heptanol) to dilute sulfuric acid as eluent in ion-exclusion chromatography using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as the stationary phase was carried out for the simultaneous separations of both (a) C1-C7 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, 2-methylvaleric, isocaproic, caproic, 2,2-dimethyl-n-valeric, 2-methylhexanoic, 5-methylhexanoic and heptanoic acids) and (b) benzenecarboxylic acids (pyromellitic, hemimellitic, trimellitic, o-phthalic, m-phthalic, p-phthalic, benzoic and salicylic acids and phenol). Heptanol was the most effective modifier in ion-exclusion chromatography for the improvement of peak shapes and a reduction in retention volumes for higher aliphatic carboxylic acids and benzenecarboxylic acids. Excellent simultaneous separation and relatively highly sensitive conductimetric detection for these C1-C7 aliphatic carboxylic acids were achieved on the TSKgel SCX column (150 x 6 mm I.D.) in 30 min using 0.5 mM sulfuric acid containing 0.025% heptanol as eluent. Excellent simultaneous separation and highly sensitive UV detection at 200 nm for these benzenecarboxylic acids were also achieved on the TSKgel SCX column in 30 min using 5 mM sulfuric acid containing 0.075% heptanol as eluent.

  5. Optimized determination of trace jet fuel volatile organic compounds in human blood using in-field liquid-liquid extraction with subsequent laboratory gas chromatographic-mass spectrometric analysis and on-column large-volume injection. (United States)

    Liu, S; Pleil, J D


    A practical and sensitive method to assess volatile organic compounds (VOCs) from JP-8 jet fuel in human whole blood was developed by modifying previously established liquid-liquid extraction procedures, optimizing extraction times, solvent volume, specific sample processing techniques, and a new on-column large-volume injection method for GC-MS analysis. With the optimized methods, the extraction efficiency was improved by 4.3 to 20.1 times and the detection sensitivity increased up to 660 times over the standard method. Typical detection limits in the parts-per-trillion (ppt) level range were achieved for all monitored JP-8 constituents; this is sufficient for assessing human fuels exposures at trace environmental levels as well as occupational exposure levels. The sample extractions are performed in the field and only solvent extracts need to be shipped to the laboratory. The method is implemented with standard biological laboratory equipment and a modest bench-top GC-MS system.

  6. Column flotation

    Energy Technology Data Exchange (ETDEWEB)

    Kohmuench, J.N.; Norrgran, D.A.; Luttrell, E.; Luttrell, G.H. [Virginia Tech. (United States)


    Over the last decade, column flotation has been recognised in the industry to be most efficient and economical means of recovering fine coal while maximizing product grade. When designed properly, flotation columns provide a high combustible recovery while maintaining a low product ash. The paper looks at the benefits of using column flotation for fine coal recovery. 2 refs., 5 figs.

  7. Ion-exclusion chromatographic separations of C1-C6 aliphatic carboxylic acids on a sulfonated styrene-divinylbenzene co-polymer resin column with 5-methylhexanoic acid as eluent. (United States)

    Ohta, Kazutoku; Towata, Atsuya; Ohashi, Masayoshi


    The application of C7 aliphatic carboxylic acids (heptanoic, 2-methylhexanoic, 5-methylhexanoic and 2,2-dimethyl-n-valeric acids) as eluents in ion-exclusion chromatography with conductimetric detection for C1-C6 aliphatic carboxylic acids (formic, acetic, propionic, isobutyric, butyric, isovaleric, valeric, isocaproic and caproic acids) was carried out using a highly sulfonated styrene-divinylbenzene co-polymer resin (TSKgel SCX) in the H+ form as a stationary phase. When using 0.05 mM sulfuric acid at pH 4.0 as the eluent, peak shapes of hydrophobic carboxylic acids (isovaleric, valeric, isocaproic and caproic acids) were tailed strongly. In contrast, when using 1 mM these C7 carboxylic acids at pH ca. 4 as the eluents, although system peaks (vacant peaks) corresponding to these C7 carboxylic acids appeared, peak shapes of these hydrophobic acids were improved drastically. Excellent simultaneous separation and relatively high sensitive conductimetric detection for these C1-C6 aliphatic carboxylic acids were achieved in 25 min on the TSKgel SCX column (150 x 6 mm I.D.) using 1 mM 5-methylhexanoic acid at pH 4.0 as the eluent.

  8. 毛细管柱气相色谱法测定通心络胶囊中冰片的含量%Capillary Column Gas Chromatographic Determination of Borneol in Tongxinluo Capsule

    Institute of Scientific and Technical Information of China (English)


      目的:建立通心络胶囊中冰片的含量的测定方法。方法:采用毛细管柱气相色谱法,以水杨酸甲酯为内标物,选择SE-54石英毛细管柱, FID检测器测定通心络胶囊中冰片的含量。结果:在该色谱条件下,样品中冰片与内标物能得到很好的分离,冰片在0.2016~2.016 mg·mL范围内线性关系良好(r=0.9998),平均加样回收率为99.84%(n=6)。结论:本方法灵敏、准确、重现性好,可用于该制剂中的冰片含量测定。%Aim: To establish a GC method for determing the contents of borneol in Tonxinluo Capsules. Method: Applying internal standard method with Methyl salicylate as internal substance. Using GC method for quantitative analysis of borneol with SE-54 capillary column, FID detector. Results: The components exhibit an excellent separability and the borneol have an good linearity in the rang of 0.2016~2.016 mg·ml(r=0.9998), with a mean recovery of borneol as high as 99.84 %(n=6). Conclusions:This method is sensitive, accurate and reproducible, and can be used to determing the borneol in Tongxinluo Capsule.

  9. Chromatographic and Related Reactors. (United States)


    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

  10. [The gas chromatographic detection of acetylene in cadaveric material]. (United States)

    Iablochkin, V D


    Acetylene traces were detected by gas chromatography in the cadaveric right crural muscle of a 30-year-old man dead from an explosion of an acetylene reservoir at a plant. Acetylene was identified using the absolute calibration method on 3 standard gas chromatographic columns, reaction gas chromatography, and acetylene "deduction" by silver sulfate on silicagel.

  11. Reading Columns


    Coutts, Marion


    Reading Columns are twin permanent public sculptures commissioned as part of a £245m scheme for the redevelopment of the Chatham Place area in Reading. Dimensions: 3.5m high x 1.3m diameter each Field of knowledge: The work consists of twin bespoke columns of stainless steel and glass over digital colour transparencies. The piece revisits and reworks the idea of the Morris Column, a 19th C feature characteristic of major European metropolitan centres. A wraparound image on each of ...

  12. PULSE COLUMN (United States)

    Grimmett, E.S.


    This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)

  13. [Use of LKhM-80 chromatograph in the analysis of urinary steroids]. (United States)

    Orlov, E N; Antipov, E M


    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.

  14. Column: lef

    NARCIS (Netherlands)

    Reep, Frans van der


    1e alinea column: Ook in je beleggingsbeslissingen is het voor echte performance wellicht tijd om eens voorbij best practices (dan word je namelijk hoogstens tweede) te kijken naar next practices. Als je op zeker speelt, verdien je weinig geld. Want anderen gingen je al voor. Maar kun je nog meer op

  15. Ion-exchange chromatographic analysis of peroxynitric acid. (United States)

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


    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.

  16. Enantiomer separation of polychlorinated biphenyls on chiral chromatographic columns of cellulose and amylose by high-performance liquid chromatography%多氯联苯在纤维素和直链淀粉衍生物类手性色谱柱上的拆分

    Institute of Scientific and Technical Information of China (English)

    尹文华; 吴丞往; 方力; 张安平


    由于多氯联苯(Polychlorinated biphenyls)的纯对映体样品非常难得,国内外大多数的研究工作仅局限于外消旋体,而较少对其对映体的环境行为、生物毒性进行研究.采用三种不同的手性色谱柱对21种手性多氯联苯在不同流动相体系进行了拆分.最终有17种手性多氯联苯达到基线或部分分离,在纯正己烷流动相体系的拆分效果最佳.直链淀粉-三(5-氯-2-甲基苯基氨基甲酸酯)固定相具有很强的手性识别能力,Lux 3u Amylose-2柱可以作为Lux 3u Cellulose-1柱手性拆分的很好补充.当手性多氯联苯分子只含一个4号位氯代或同时含有5,5,号位氯代时,三种手性色谱柱较难对其分离完全.该方法分离速度快,可以作为纯对映体样品的制备方法.%Due to the enantiomer of polychlorinated biphenyls is rare, most of researches were focused on racemes, rather than environmental behavior or biotoxicity of enantiomer at home and abroad. The work investigated enantiomeric separation of 21 kinds of polychlorinated biphenyls with different chiral chromatographic columns by high-performance liquid chromatography. 17 kinds of PCBs achieved baseline or were at least partially separated. This was proved to be the most efficient for the chiral separation of 100% n-hexane mobile phase. As a kind of chiral stationary phases (CSPs), amylose tris (5-chlorine 2-methylphenylcarbamate) has a strong capacity of chiral recognition. Lux 3u Amylose-2 CSP is a great complementary for the chiral separation of Lux 3u Cellulose-1 CSP. The separations are difficult to be achieved for these three CSPs when polychlorinated biphenyls with chlorine substitution only in 4 position or in 5, 5' positions simultaneously. However, this approach could be used to obtain pure enantiomer of PCBs.

  17. Can enantiomers be separated in achiral chromatographic systems? (United States)

    Davankov, V. A.


    Consideration of chromatography of a nonracemic mixture on an achiral sorbent from a stereochemical point of view allows the claim that partial separation of the excess enantiomer zone from the racemate zone is possible only with analytes capable of self-associating under the conditions of the chromatographic column. It is from these positions that features of this process can be explained and conditions for its maximal proceeding formulated.

  18. Multicapillary columns with a porous layer based on the divinylbenzene copolymer (United States)

    Patrushev, Yu. V.; Nikolaeva, O. A.; Sidelnikov, V. N.


    A method for preparing a multicapillary column with a porous layer based on the styrene-divinylbenzene copolymer has been developed. The column makes it possible to quickly separate C1-C4 hydrocarbons and oxygen-containing compounds. The main chromatographic properties of the columns were studied.

  19. Headspace chromatographic determination of water pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Otson, R.; Williams, D.T.


    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 and linear plots of peak area against concentration in the range 0.25-16 were obtained for 32 compounds. At aqueous concentrations of 4 and 16, 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 for 6 weeks at 4/sup 0/C did not usually affect analytical results by more than +/- 15%.

  20. Functional Polymers for Chromatographic Enantiomer Separation

    Institute of Scientific and Technical Information of China (English)

    S. Allenmark; L. Thunberg


    @@ 1Introduction Today, methods to obtain pure enantiomers of organic compounds are of extreme importance, not the least due to the demands imposed on the pharmaceutical industry. Separation of the two enantiomers in a racemate is necessary in order to study possible differences in biological activity. Consequently, research on methods for direct chromatographic resolution by means of columns containing a chiral stationary phase (CSP) has been intense during the last decades and a wide variety of CSPs,many of which commercially available,exist today.Polymeric CSPs have been made from naturally occurring polymers (cellulose, amylose) via suitable derivatization, as well as either by polymerization of chiral monomers or via asymmetric catalysis to yield linear, isotactic polymers of a predominantly single-handed helicity. An excellent review of the field[1], with special emphasis on preparative applications, was published in 1994.

  1. Liquid chromatographic determination of furazolidone in shrimp. (United States)

    Stehly, G R; Plakas, S M; el Said, K R


    A liquid chromatographic (LC) method was developed for the quantitation of furazolidone residues in shrimp muscle. The shrimp homogenate (1.0 g) is extracted with acetonitrile, and the extract is taken to dryness. The residue is dissolved in acetonitrile, and the solution is passed through alumina and C18 cleanup columns. The eluate is taken to dryness and reconstituted in a suitable solvent for reversed-phase (C18) LC with UV detection at 365 nm. Recoveries of furazolidone from shrimp homogenates spiked from 5 to 80 ng/g ranged from 74.3 to 79.7%, and relative standard deviations (RSDs) were 5.0-8.9%. RSDs for incurred furazolidone quantitated at 5.9 and 9.2 ng/g were 6.6 and 7.6%, respectively.

  2. High-separation performance of chromatographic capillaries coated with MOF-5 by the controlled SBU approach. (United States)

    Münch, Alexander S; Seidel, Jürgen; Obst, Anja; Weber, Edwin; Mertens, Florian O R L


    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.

  3. Optimization of the gas chromatographic separations; Optimacion de las separaciones cromatograficas en fase gaseosa

    Energy Technology Data Exchange (ETDEWEB)

    Gasco Sanchez, L.


    A review and a critical study on the optimization of the gas chromatographic separations are made. After dealing with the fundamental gas chromatographic equations, some methods of expressing column performances are discussed: performance indices, performance parameters, resolution and effective plate number per unit time. This is completed with a comparative study on performances of various types of columns. Moreover, optimization methods for operating chromatographic conditions are extensively dealt with: as resolution optimization, separation time, and normalization techniques for the time of analysis in order to achieve the maximum resolution at constant time. Finally, some others non operating parameters such as: selectivity of stationary phases, column preparation and optimization methods by means of computers are studied. (Author) 68 refs.

  4. Chromatographic separation of fructose from date syrup. (United States)

    Al Eid, Salah M


    The objective of this study is to provide a process for separating fructose from a mixture of sugars containing essentially fructose and glucose, obtained from date palm fruits. The extraction procedure of date syrup from fresh dates gave a yield of 86.5% solids after vacuum drying. A process for separating fructose from an aqueous solution of date syrup involved adding the date syrup solutions (20, 30 and 40% by weight) to a chromatographic column filled with Dowex polystyrene strong cation exchange gel matrix resin Ca2 + and divinylbenzene, a functional group, sulfonic acid, particle size 320 microm, with a flow rate of 0.025 and 0.05 bed volume/min, under 30 and 70 degrees C column temperature. After the date sugar solution batch, a calculated quantity of water was added to the column. Glucose was retained by the resin more weakly than fructose and proceeded faster into the water batch flowing ahead. Three fractions were collected: a glucose-rich fraction, a return fraction, and a fructose-rich fraction. The return fraction is based on when the peaks of fructose and glucose were reached, which could be determined by means of an analyzer (polarimeter) based on the property of glucose and fructose solutions to turn the polarization level of polarized light. A high yield of fructose is obtained at 70 degrees C column temperature with a flow rate of 0.025 bed volume/min and date syrup solution containing 40% sugar concentration. The low recovery by weight obtained using date syrup solutions having a sugar concentration of 20 and 30%, encourages the use of a concentration of 40%. However, with the 40% date syrup supply the average concentrations of glucose and fructose in the return fractions were more than 40%, which can be used for diluting the thick date syrup solution extracted from dates.

  5. Chromatographic separation and concentration of quercetin and (+)-catechin using mesoporous composites based on MCM-41 (United States)

    Karpov, S. I.; Belanova, N. A.; Korabel'nikova, E. O.; Nedosekina, I. V.; Roessner, F.; Selemenev, V. F.


    Data on chromatographic separation of quercetin and (+)-catechin-flavonoids with similar physicochemical (including sorption) properties—are presented. The highest efficiency of chromatographic process at high sorption capacity of the material with respect to quercetin and slightly lower capacity for (+)-catechin were observed when silylated composites of ordered MCM-41 type materials were used. The application of acetonitrile as a solvent increased the sorption capacity of the material and can be recommended for separation of related polyphenol substances and their determination using ordered MCM-41 modified with trimethylchlorosilane as a stationary phase in a chromatographic column.

  6. pH和色谱柱对日本鳗鲡肝脏抗菌肽分离纯化效果的影响及抗菌活性检测%Effects of pH and chromatographic column on isolation,purification of antibacterial peptide from Japanese eel liver,and determination of antibacterial activity

    Institute of Scientific and Technical Information of China (English)

    张东玲; 关瑞章; 黄文树; 熊静; 徐继松; 宋宝东


    In order to quickly isolate and purify antimicrobial peptide, different flow phase pH values (cation change pH 3. 0,4. 0,5. 0, and reverse-phase liquid chromatography pH 2. 0,4. 5,7. 0), and different chromatographic columns ( cation-change and gel chromatography coupled with reverse-phase liquid chromatography respectively) were used to isolate and purify antibacterial peptide from Anguilla japonica liver,and the results were analysed and compared. The merits and drawbacks of agar plate diffusion and microporous liquid culture methods on determination of antibacterial activity were analysed. The results showed that pH 4.0 buffer solution was the best flow phase in three-pH-value buffer solutions, which had 16.43% extraction ratio and isolated two elution peaks;We did not obtain perfect result from reverse-phase liquid chromatography ( RPC ) in three-pH-value buffer solutions;Sephadex G-25 gel coupled with RPC significantly improved the isolation effect, elution peak amounts were greater, peaks were sharper and narrower,baseline was flatter and low than those of cation exchange coupled with RPC. Agar plate diffuse method to determine antibacterial activity was simple to operate, and experimental result was intuitional. It required much protein,so it should be used to determine antibacterial activity during protein crude extraction period;Microporous liquid culture method to determine antibacterial activity was sensitive. It required little protein, so it should be used to determine antibacterial activity during isolation and purification of protein in chromatography period.%为了能够快捷地分离纯化出单一的抗菌肽,实验采用不同pH值(离子交换流动相pH3.0、4.0、5.0;反相液相层析流动相pH 2.0、4.5、7.0)缓冲液,不同色谱柱(离子交换和凝胶过滤层析柱分别与反相液相层析柱)联用对日本鳗鲡肝脏抗菌肽分离纯化效果进行了比较,并分析了琼脂板扩散法和微孔液体培

  7. 一种近红外光谱在线监测新方法及其在中药柱层析过程中的应用%A Novel Online Process Monitoring Method Based on Near Infrared Spectroscopy and Its Application to the Column Chromatographic Separation for Traditional Chinese Medicine

    Institute of Scientific and Technical Information of China (English)

    杨辉华; 郭拓; 马晋芳; 唐天彪; 梁琼麟; 王义明; 罗国安


    Near infrared spectroscopy(NIRS) is a process analysis and monitoring tool with many advantages, while it needs to set up quantitative or discriminative calibration models in advance, and needs to adjust these models when the process conditions are varied, which makes it difficult for ordinary user to take its full advantage of it To tackle this problem, this paper presented a novel, simple and model-free methodology for online process monitoring based on two reciprocal viewpoints of measuring the variability of spectroscopy-both the similarity and dissimilarity of process spectrum, i. e. , the adaptive moving window standard deviation function(AMWSW) and similarity function(S). The methodology was validated by a column chromatography process of traditional Chinese medicine using near infrared spectroscopy. The online trend curves of AMWSW and S obtained by proposed method were validated by a comparison with the content variation curves of multiple indicative components analyzed by high performance liquid chromatography ( HPLC), and these trend curves demonstrated their potential for real-time process status monitoring, accurately determining the beginning point, the peak point, the end point of the elution, and the phase change from water solution to ethanol solution. The proposed methodology can also be used to other process analysis techniques, such as ultraviolet/visible, infrared, Raman, fluorescence, chromatograph and mass spectrum.%近红外光谱(NIRS)广泛应用于生产过程分析与监测,常需事先建立定量校正或定性判别模型,并需在生产条件变化后调整模型,使用较复杂.本文从相异度和相似度两个对立互补的角度,提出自适应移动窗口标准差法和过程光谱相似度法,并以此为基础建立一种针对生产过程的无需校正模型的简易光谱在线监测方法.论文以中药柱层析过程为例,对监测过程作NIRS自适应移动窗口标准差趋势图和过程光谱相似度趋势图,

  8. Performance of chromatographic systems to model soil-water sorption. (United States)

    Hidalgo-Rodríguez, Marta; Fuguet, Elisabet; Ràfols, Clara; Rosés, Martí


    A systematic approach for evaluating the goodness of chromatographic systems to model the sorption of neutral organic compounds by soil from water is presented in this work. It is based on the examination of the three sources of error that determine the overall variance obtained when soil-water partition coefficients are correlated against chromatographic retention factors: the variance of the soil-water sorption data, the variance of the chromatographic data, and the variance attributed to the dissimilarity between the two systems. These contributions of variance are easily predicted through the characterization of the systems by the solvation parameter model. According to this method, several chromatographic systems besides the reference octanol-water partition system have been selected to test their performance in the emulation of soil-water sorption. The results from the experimental correlations agree with the predicted variances. The high-performance liquid chromatography system based on an immobilized artificial membrane and the micellar electrokinetic chromatography systems of sodium dodecylsulfate and sodium taurocholate provide the most precise correlation models. They have shown to predict well soil-water sorption coefficients of several tested herbicides. Octanol-water partitions and high-performance liquid chromatography measurements using C18 columns are less suited for the estimation of soil-water partition coefficients.

  9. Column Selection for Biomedical Analysis Supported by Column Classification Based on Four Test Parameters. (United States)

    Plenis, Alina; Rekowska, Natalia; Bączek, Tomasz


    This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the FKUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the FKUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the FKUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the FKUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis.

  10. Evaluation of superficially porous and fully porous columns for analysis of drugs in plasma samples by UHPLC-MS/MS. (United States)

    Acquaro, Vinicius Ricardo; Lanças, Fernando Mauro; Queiroz, Maria Eugênia Costa


    This work compares the performance of recently introduced C18 superficially porous columns (four columns) and C18 fully porous columns (two columns), with different particle sizes, during the analysis of drugs in plasma samples by MS/MS detection. The following chromatographic parameters were evaluated for all the columns: reduced plate height (h) vs reduced linear velocity (v), impedance vs v, chromatographic run time vs flow rate (mLmin(-1)), backpressure vs flow rate (mLmin(-1)), resolution, peak capacity, asymmetry, and retention factor. By using DAD detection, hydrophobicity, silanol activity, and metal impurities were also assessed for the columns. The columns with charged surface displayed improved chromatographic efficiency for the drugs in their ionized form. The columns with particles smaller than 2μm (Cortecs 1.6μm, Acquity 1.7μm, and Kinetex 1.7μm) presented higher chromatographic efficiency for the drugs, which were in their partially ionized form. The generated mathematical models were able to predict the backpressure and chromatographic run time at different flow rates for all the columns. Considering the efficiency, impedance, resolution, peak capacity, retention factor, and hydrophobicity, Cortecs 1.6μm and Acquity 1.7μm were the columns that given the best performance during analysis of the target drugs in plasma samples.

  11. A Simple Design to Realize Micro-column Separation by Conventional Analytical HPLC

    Institute of Scientific and Technical Information of China (English)

    GONG,Wenjun; ZHANG,Junxia; ZHANG,Yuping; ZHANG,Yijun; TIAN,Mengkui; WU,Dafu


    The conventional analytical HPLC was successfully developed for micro-column separation by using a simple eluate splitting system,self-preparation of packing column and on-capillary column detector in our laboratory.Porous inlet frit in fused silica capillary was rapidly prepared by sintering stainless steel powders under 500 meshes for about 20 s.The use of such frits or metal meshes in capillary to retain C18 particles of chromatographic packing was demonstrated to be stable and specially robust with continuous packing and long chromatographic runs.Furthermore,the chromatographic behavior was detailedly evaluated by changing the flow rate and the percentage of mobile phase using the prepared capillary column.Under the optimal experimental conditions,baseline separation of the model analytes including thiourea,benzene,toluene,ethylbenzene was obtained with a high column efficiency near 70000N (plates/m) by the developed capillary-HPLC.

  12. Identification of humic-like substances (HULIS) in oxygenated organic aerosols using NMR and AMS factor analyses and liquid chromatographic techniques

    NARCIS (Netherlands)

    Paglione, M.; Kiendler-Scharr, A.; Mensah, A.A.; Finessi, E.; Giulianelli, L.; Sandrini, S.; Facchini, M.C.; Fuzzi, S.; Schlag, P.; Piazzalunga, A.; Tagliavini, E.; Henzing, J.S.; Decesari, S.


    The atmospheric organic aerosol composition is characterized by a great diversity of functional groups and chemical species, challenging simple classification schemes. Traditional offline chemical methods identify chemical classes based on the retention behaviour on chromatographic columns and absor

  13. Identification of humic-like substances (HULIS) in oxygenated organic aerosols using NMR and AMS factor analyses and liquid chromatographic techniques

    NARCIS (Netherlands)

    Paglione, M.; Kiendler-Scharr, A.; Mensah, A. A.; Finessi, E.; Giulianelli, L.; Sandrini, S.; Facchini, M. C.; Fuzzi, S.; Schlag, P.; Piazzalunga, A.; Tagliavini, E.; Henzing, J. S.; Decesari, S.


    The atmospheric organic aerosol composition is characterized by a great diversity of functional groups and chemical species challenging simple classification schemes. Traditional off-line chemical methods identified chemical classes based on the retention behavior on chromatographic columns and abso

  14. Ion Exchange and Thin Layer Chromatographic Separation and Identification of Amino Acids in a Mixture: An Experiment for General Chemistry and Biotechnology Laboratories (United States)

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


    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…

  15. Gas Chromatographic Mass Spectrometric Determination of Myo-inositol in Humans Utilizing a Deuterated Internal Standard

    DEFF Research Database (Denmark)

    Andersen, Jan Rud; Larsen, Elfinn; Harbo, Helge;


    , was added as internal standard to the samples at an early stage in the analytical procedure. After separation and derivatization to the hexa-acetate, the gas chromatographic mass spectrometric analysis was carried out. A 25 m fused silica capillary column coated with methyl silicone was used, and the ions...

  16. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ying [Iowa State Univ., Ames, IA (United States)


    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

  17. Chromatographic Separations of Enantiomers and Underivatized Oligosaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Ying Liu


    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

  18. Chromatographic removal and heat inactivation of hepatitis A virus during manufacture of human albumin. (United States)

    Adcock, W L; MacGregor, A; Davies, J R; Hattarki, M; Anderson, D A; Goss, N H


    CSL Limited, an Australian biopharmaceutical company, has recently converted its method of manufacture for human albumin from a traditional Cohn-ethanol fractionation method to a method employing chromatographic techniques. Studies were undertaken to determine the efficiency of the chromatographic and pasteurization steps used in the manufacture of Albumex(R) (CSL's trade name for albumin) in removing and inactivating the potential viral contaminant, hepatitis A virus (HAV). The manufacturing process for Albumex(R) includes three chromatographic steps, two of which are ion-exchange steps (DEAE-Sepharose(R) Fast Flow and CM-Sepharose(R) Fast Flow) and the third is a gel-filtration step (Sephacryl(R) S200 HR). The final stage of the Albumex(R) process involves a bulk pasteurization step where product is held at 60 degrees C for 10 h. HAV partitioning experiments on the DEAE-Sepharose(R) FF and CM-Sepharose(R) FF ion-exchange and Sephacryl(R) S200 HR gel-filtration columns were performed with scaled-down models of the production-scale chromatographic Albumex(R) process. Production samples collected before each of the chromatographic steps were spiked with HAV and processed through each of the scaled-down chromatographic columns. Samples collected during processing were assayed and the log10 reduction factors calculated. Inactivation kinetics of HAV were examined during the pasteurization of Albumex(R) 5 and 20 [5% and 20% (w/v) albumin solutions] held at 60 degrees C for 10 h. Log10 reductions for HAV through the DEAE-Sepharose(R) FF, CM-Sepharose(R) FF and Sephacryl(R) S200 HR chromatographic columns were 5.3, 1.5 and 4.2 respectively, whereas a 4.4 and a greater than 3.9 log10 reduction in HAV in Albumex(R) 5 and 20 respectively were achieved during pasteurization.

  19. Improving the productivity of a multidimensional chromatographic preparative system by collecting pure chemicals after each of three chromatographic dimensions. (United States)

    Sciarrone, Danilo; Pantò, Sebastiano; Donato, Paola; Mondello, Luigi


    The enhanced sample collection capability of a heart-cutting three-dimensional GC-prep system is reported. In its original configuration, a highly pure component can be usually collected after the last (3D) column outlet by means of a dedicated preparative station. The latter is located after the last chromatographic column, and this poses the requirement for multiple heart cuts even for those components showing satisfactory degree of purity after the first (or second) separation dimension. The feasibility to collect pure components after each chromatographic dimension is here described, employing a three-dimension MDGC system equipped with high-temperature valves, located inside the first and second GC ovens, with the aim to improve the productivity of the collection procedure. In addition to a commercial preparative collector located at the 3D outlet, two laboratory-made collection systems were applied in the first and second dimension, reached by the effluent to be collected trough a high-temperature valve switching the heart-cut fraction between either the detector (FID), or the collector. Highly pure sesquiterpene components were collected, namely: patchouli alcohol after the first column [poly(5% diphenyl/95% dimethylsiloxane)], α-bulnesene after a second column coated with high molecular weight polyethylene glycol, and α-guaiene after an ionic-liquid based column (SLB-IL60), used as the third dimension. Purity levels ranging from 85 to 95% were achieved with an average collection recovery of 90% (n=5). The following average amounts were collected per run: 160μg for α-guaiene, 295μg for α-bulnesene, and 496μg for patchouli alcohol.

  20. Monolithic columns with organic sorbent based on poly-1-vinylimidazole for high performance liquid chromatography (United States)

    Patrushev, Y. V.; Sidelnikov, V. N.; Yudina, Y. S.


    Monolithic chromatographic columns for HPLC with sorbent based on 1-vinylimidazole are prepared. It is shown that changing the 1-vinylimidazole content in the initial solution allows us to change the polarity of columns. An example of aromatic hydrocarbons separation is presented.

  1. Planar gas chromatography column on glass plate with nanodispersed silica as the stationary phase (United States)

    Platonov, I. A.; Platonov, V. I.; Pavelyev, V. S.; Agafonov, A. N.


    The paper presents the GC column in the plane of the glass plate with the adsorption layer nanodispersed silica. Created gas chromatographic column allows to separate a mixture of five alkanes from pentane to nonane in isothermal (90 ° C) mode less than one minute.

  2. Chromatographic Separation of Vitamin E Enantiomers

    Directory of Open Access Journals (Sweden)

    Ju-Yen Fu


    Full Text Available Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture. Similarly, with only one chiral center, natural tocotrienols occur as the R-isoform. In this review, we aim to discuss a few chromatographic methods that had been used to separate the stereoisomers of tocopherols and tocotrienols. These methods include high performance liquid chromatography, gas chromatography and combination of both. The review will focus on method development including selection of chiral columns, detection method and choice of elution solvent in the context of separation efficiency, resolution and chiral purity. The applications for separation of enantiomers in vitamin E will also be discussed especially in terms of the distinctive biological potency among the stereoisoforms.

  3. Automated Composite Column Wrapping


    ECT Team, Purdue


    The Automated Composite Column Wrapping is performed by a patented machine known as Robo-Wrapper. Currently there are three versions of the machine available for bridge retrofit work depending on the size of the columns being wrapped. Composite column retrofit jacket systems can be structurally just as effective as conventional steel jacketing in improving the seismic response characteristics of substandard reinforced concrete columns.

  4. 二氧化碳中环氧乙烷和乙醛分离色谱柱的选择%Selection of Column for Separation Acetaldehyde And Ethylene Oxide in Carbon Dioxide

    Institute of Scientific and Technical Information of China (English)

    边鲁宁; 王崇


    Discussing the ethyene oxide and acetaldehyde separation in carbon dioxide that related to the chromatographic column.Do the experiments, determine the chromatographic column and chromatographic condition .Conclusion separation effect in order to get the best chromatographic column .%讨论二氧化碳中环氧乙烷和乙醛分离有关的色谱柱。进行相关实验,确定色谱柱、色谱条件的选择,总结其分离效果,得出最佳色谱柱。

  5. [Ion-pair chromatography-indirect ultraviolet detection for determination of tetraethyl ammonium using a monolithic column and a packed column]. (United States)

    Zou, Chunmiao; Zhang, Xiaodong; Yu, Hong; Guan, Chao; Wang, Miaoyu


    Two methods were developed for the determination of tetraethyl ammonium by ion-pair chromatography-indirect ultraviolet detection using a monolithic column and a packed column with ionic liquid as additive in mobile phase. Chromatographic separations were performed on a monolithic column and a packed column both on reversed phase using imidazolium ionic liquid aqueous solution-ion-pair reagent-organic solvent as mobile phase. The effects of the background ultraviolet absorption reagent, detection wavelength, ion-pair reagent, organic solvent, column temperature and flow rate on the determination of tetraethyl ammonium were investigated. The difference between the two chromatographic columns was compared and the retention rules were discussed. Under the optimized chromatographic conditions, for tetraethyl ammonium on monolithic column and packed column, the retention times were 2.40 and 3.02 min; the detection limits (S/N=3), 0.04 and 0.07 mg/L; the RSDs (n = 5) for peak areas, 0.16% and 0.11%; and the RSDs (n=5) for retention times, 0.02% and 0.01%, respectively. The two methods have been successfully applied to the determination of tetraethyl ammonium ionic liquids synthesized by laboratory. The recoveries of the tetraethyl ammonium after spiking were 98.2% and 99.1%, respectively. The two methods can meet the requirements for the quantitative analysis of tetraethyl ammonium.

  6. Ion Chromatographic Analyses of Sea Waters, Brines and Related Samples

    Directory of Open Access Journals (Sweden)

    Nataša Gros


    Full Text Available This review focuses on the ion chromatographic methods for the analyses of natural waters with high ionic strength. At the beginning a natural diversity in ionic composition of waters is highlighted and terminology clarified. In continuation a brief overview of other review articles of potential interest is given. A review of ion chromatographic methods is organized in four sections. The first section comprises articles focused on the determination of ionic composition of water samples as completely as possible. The sections—Selected Anions, Selected Cations and Metals—follow. The most essential experimental conditions used in different methods are summarized in tables for a rapid comparison. Techniques encountered in the reviewed articles comprise: direct determinations of ions in untreated samples with ion- or ion-exclusion chromatography, or electrostatic ion chromatography; matrix elimination with column-switching; pre-concentration with a chelation ion chromatography and purge-and-trap pre-concentration. Different detection methods were used: non-suppressed conductometric or suppressed conductometric, direct spectrometric or spectrometric after a post-column derivetization, and inductively coupled plasma in combination with optical emission or mass spectrometry.

  7. Liquid Chromatographic Determination of Alogliptin in Bulk and in its Pharmaceutical Preparation


    El-Bagary, Ramzia I.; Elkady, Ehab F.; Ayoub, Bassam M.


    In this work, a reversed-phase liquid chromatographic (RP-LC) method has been developed for the determination of alogliptin (ALG) based on isocratic elution using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (4.6)-acetonitrile (20:80, v/v) at a flow rate of 1 mL min−1 with UV detection at 215 nm. Chromatographic separation was achieved on a Symmetry® cyanide column (150 mm × 4.6 mm, 5 μm). Linearity, accuracy and precision were found to be acceptable over the concentr...

  8. Identification and quantification of flavonoids in human urine samples by column switching liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry

    DEFF Research Database (Denmark)

    Nielsen, Salka E.; Freese, R.; Cornett, C.


    A rapid and sensitive high-performance liquid chromatographic mass spectrometric (HPLC-MS) method is described for the determination and quantification of 12 dietary flavonoid glycosides and aglycons in human urine samples. Chromatographic separation of the analytes of interest was achieved...... by column-switching, using the first column (a Zorbax 300SB C-3 column) for sample cleanup and eluting the heart-cut flavonoid fraction onto the second column (a Zorbax SE C-18 column) for separation and detection by ultraviolet and atmospheric pressure chemical ionization MS using single ion monitoring...... with high and low flavonoid content was analyzed, and the results are reported....

  9. Evaluation of column hardware on liquid chromatography-mass spectrometry of phosphorylated compounds. (United States)

    Sakamaki, Hiroshi; Uchida, Takeharu; Lim, Lee Wah; Takeuchi, Toyohide


    The influences of column hardware, such as chromatographic tubes and frits, on liquid chromatography-mass spectrometry (LC-MS) analysis of phosphorylated compounds were evaluated. The signal to noise ratio (S/N) and the intensity of flavin adenine dinucleotide (FAD) using a glass lined tube and polyethylene frit (GL-PE) column was approximately 170 and 90 times higher, respectively, than those using conventional stainless steel tube and stainless steel frit (S-S) column. In addition, the retention time of FAD using GL-PE column was the shortest compared to other columns. Interaction between phosphorylated compounds and metal ions in the flow path in the S-S column was stronger than that between them and the GL-PE column. Thus, the metal ions in the flow path in GL-PE column were low. Since the specific surface area of a pair of frits was 70 times larger than that of a chromatographic tube (150 mm×2.1 mm), the frits were found to have more effective improvement of the S/N as well as the intensity than the chromatographic tubes, when phosphorylated compounds were analyzed by LC-MS. When the evaluated phosphorylated compounds were analyzed by LC-MS(/MS) using a GL-PE column, the intensity and S/N were increased.

  10. Vibrational Spectroscopy of Chromatographic Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jeanne E. Pemberton


    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.

  11. Multivariate curve resolution based chromatographic peak alignment combined with parallel factor analysis to exploit second-order advantage in complex chromatographic measurements. (United States)

    Parastar, Hadi; Akvan, Nadia


    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.

  12. Monolithic molecularly imprinted polymeric capillary columns for isolation of aflatoxins. (United States)

    Szumski, Michał; Grzywiński, Damian; Prus, Wojciech; Buszewski, Bogusław


    Monolithic molecularly imprinted polymers extraction columns have been prepared in fused-silica capillaries by UV or thermal polymerization in a two-step process. First, a poly-(trimethylolpropane trimethacrylate) (polyTRIM) core monolith was synthesized either by UV or thermal polymerization. Then it was grafted with the mixture of methacrylic acid (MAA) as a functional monomer, ethylene dimethacrylate (EDMA) as a cross-linking agent, 5,7-dimethoxycoumarin (DMC) as an aflatoxin-mimicking template, toluene as a porogen solvent and 2,2-azobis-(2-methylpropionitrile) (AIBN) as an initiator of the polymerization reaction. Different thermal condition of the photografting and different concentrations of the grafting mixture were tested during polymerization. The extraction capillary columns were evaluated in the terms of their hydrodynamic and chromatographic properties. Retention coefficients for aflatoxin B1 and DMC were used for assessment of the selectivity and imprinting factor. The obtained results indicate that the temperature of photografting and concentration of the grafting mixture are key parameters that determine the quality of the prepared MIPs. From the MIP columns characterized by the highest permeability the column of the highest imprinting factor was applied for isolation of aflatoxins B1, B2, G1 and G2 from the model aqueous sample followed by on-line chromatographic separation. The process was performed using a micro-MISPE-microLC-LIF system of a novel design, which allowed for detection of the eluates from the sample preparation part as well as from the chromatographic separation.

  13. Transesterification of propylene glycol methyl ether in chromatographic reactors using anion exchange resin as a catalyst. (United States)

    Oh, Jungmin; Sreedhar, Balamurali; Donaldson, Megan E; Frank, Timothy C; Schultz, Alfred K; Bommarius, Andreas S; Kawajiri, Yoshiaki


    Reactive chromatography using an anion exchange resin is proposed for a transesterification reaction of propylene glycol methyl ether (DOWANOL™ PM) with ethyl acetate to produce propylene glycol methyl ether acetate (DOWANOL™ PMA). This reaction is studied in batch and chromatographic reactors catalyzed by an anion exchange resin. Several anion exchange resins are tested and compared based on the performance of resin as an adsorbent and a catalyst. A chromatographic column is packed with a selected catalyst, AMBERLITE™ IRA904, and both reaction and chromatographic elution are studied at different temperatures and feed concentrations. The resulting chromatograms are fitted to a mathematical model to obtain adsorption equilibrium and reaction kinetic parameters by the inverse method. Compared to esterification investigated in a previous study, transesterification has advantages such as a higher conversion at lower temperature and easy removal of the byproduct which may lead to higher productivity. Deactivation of anion exchange resins is observed and potential solutions are suggested.

  14. Stationary phase modulation in liquid chromatography through the serial coupling of columns: A review. (United States)

    Alvarez-Segura, T; Torres-Lapasió, J R; Ortiz-Bolsico, C; García-Alvarez-Coque, M C


    Liquid chromatography with single columns often does not succeed in the analysis of complex samples, in terms of resolution and analysis time. A relatively simple solution to enhance chromatographic resolution is the modulation of the stationary phase through the serial coupling of columns. This can be implemented with any type of column using compatible elution conditions and conventional instruments. This review describes the key features of column coupling and published procedures, where two or more columns were coupled in series to solve separation problems. In all reports, the authors could not resolve their samples with single columns, whereas significant enhancement in chromatographic performance was obtained when the columns were combined. Particularly interesting is the reduction in the analysis time in the isocratic mode, which alleviates the "general elution problem" of liquid chromatography, and may represent a stimulus for the proposal of new procedures, especially in combination with mass spectrometric, electrochemical and refractometric detection. Developments proposed to make the serial coupling of columns useful in routine and research laboratories are outlined, including optimisation strategies that facilitate the selection of the appropriate column combination and elution conditions (solvent content, flow rate or temperature) in both isocratic and gradient modes. The availability of zero dead volume couplers, able to connect standard columns, and the commercialisation of short columns with multiple lengths, have expanded the possibilities of success.

  15. Perpentylated (2, 3, 6-Tri-O-pentyl)-β-cyclodextrin Used as Capillary Gas Chromatographic Stationary Phase Prepared by Sol-gel Technology

    Institute of Scientific and Technical Information of China (English)

    Min Min LIANG; Mei Ling QI; Yu LENG; Ruo Nong FU


    Capillary column preparation using perpentylated (2,3,6-tri-O-pentyl)-β-cyclodextrin as stationary phase by sol-gel technology with simplicity and rapidity is described. Multiple preparation steps in conventional column technology were avoided. The prepared columns exhibit satisfactory chromatographic performances and pronounced selectivity for a wide range of test solutes, and have been successfully used for the separation of nitrotoluene, dimethoxybenzene,alcohols, alkanes, dimethylphenol and cresol isomers.


    This paper summarizes the key points of a joint study between the EPA and Metrohm-Peak, Inc., on the use of polyvinyl alcohol [PVA] columns for the ion chromatographic determination of percholorate in aqueous leachates or solutions of fertilizers. A series of fertilizer samples ...

  17. Fast preparation of photopolymerized monolithic columns for capillary electrochromatography

    Institute of Scientific and Technical Information of China (English)

    GONG Wen-jun; XU Guang-ri; ZHANG Yi-jun; ZHANG Yu-ping; CHOI Seong-ho; LEE Kwang-pill


    Photopolymerized sol-gel(PSG) columns were prepared using methacryloxypropyltrimethoxysilane as the monomer,toluene as the porogen and hydrochloric acid as the catalyst. Four different photoinitiators such as benzoin methyl ether, Irgacure 819,lrgacure 1700 and Irgacure 1800 were comparatively used in the reaction solution in the presence and absence of sodium dodecylsulfate. The above eight solutions were respectively irradiated at 365 um for 5-10 min in each capillary (75 μm inside diameter) toprepare the porous monolithic sol-gel column by a one-step, in situ, process. The chromatographic behavior of the eight PSGcolumns were comparatively studied, all of which exhibit reversed-phase character. Using these columns, several neutral compounds,namely thiourea, benzene, toluene, ethyl benzene, biphenyl and naphthalene can be separated from mixtures with a largest columnefficiency of 74 470 plate/column for thiourea. Addition of sodium dodecyl sulfate in the polymerization process has a significantinfluence on the morphology and migration time.

  18. Determination of cyclodextrins in biological fluids by high-performance liquid chromatography with negative colorimetric detection using post-column complexation with phenolphthalein

    NARCIS (Netherlands)

    Frijlink, H.W.; Visser, J.; Drenth, B.F.H.


    A rapid and sensitive high-performance liquid chromatographic method for the analysis of beta- and gamma-cyclodextrin in aqueous biological fluids such as plasma, urine, or tissue homogenate is described. The chromatographic system consists of a microBondapak Phenyl column as stationary phase and a

  19. 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))


    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.

  20. 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)


    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.

  1. Mass transfer kinetics, band broadening and column efficiency. (United States)

    Gritti, Fabrice; Guiochon, Georges


    Important progress was recently made in our understanding of the physico-chemical aspects of mass transfer kinetics in chromatographic columns, in methods used for accurate determination of the different contributions to the height equivalent to a theoretical plate (HETP), and in the application of these advances to the elucidation of mass transfer mechanisms in columns packed with recent chromatographic supports (sub-2 μm fully porous particles, sub-3 μm core-shell particles, and monoliths). The independent contributions to the HETP are longitudinal diffusion, eddy dispersion, liquid-solid mass transfer (including trans-particle or trans-skeleton mass transfer and external film mass transfer), and the contributions caused by the thermal heterogeneity of the column. The origin and importance of these contributions are investigated in depth. This work underlines the areas in which improvements are needed, an understanding of the contribution of the external film mass transfer term, a better design of HPLC instruments providing a decrease of the extra-column band broadening contributions to the apparent HETP, the development of better packing procedures giving more radially homogeneous column beds, and new packing materials having a higher thermal conductivity to eliminate the nefarious impact of heat effects in very high pressure liquid chromatography (vHPLC) and supercritical fluid chromatography (SFC).

  2. Optimization of Chromatographic Conditions for Detecting Ellagic Acid in Pomegranate Peels Using HPLC Method

    Institute of Scientific and Technical Information of China (English)


    [Objective] This study aimed to optimize the chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method. [Method] By using 0.2 mg/ml ellagic acid standard solution, on the basis of single-factor experiment and orthogonal experiment, chromatographic conditions (mobile phase ratio, flow rate, col- umn temperature) for detecting ellagic acid using HPLC were optimized. Based on the optimal chromatographic conditions, the ellagic acid content in experimental pomegranate peels was determined. [Resull] The optimal chromatographic conditions for detecting ellagic acid in pomegranate peels using HPLC method are: 1.2% phos- phoric acid:acetonitrile=85:15, column temperature of 35 ℃, and flow rate of 1.0 ml/min. The linear regression equation of ellagic acid is: y=2.9e+0.6x+4.4e+5 (FF=9 999). Ac- cording to the standard addition recovery test, the average recovery rate of ellagic acid is 98.20%, and RSD is 0.60%. Under above optimized chromatographic condi- tions, ellagic acid can be well separated from other interfering components in pomegranate peels, with shorter peak time and ideal effect, which is convenient for the detection in production practices. [Conclusion] This study laid the foundation for detecting ellagic acid in pomegranate peels using HPLC method.

  3. Improved micromachined column design and fluidic interconnects for programmed high-temperature gas chromatography separations. (United States)

    Gaddes, David; Westland, Jessica; Dorman, Frank L; Tadigadapa, Srinivas


    This work focuses on the development and experimental evaluation of micromachined chromatographic columns for use in a commercial gas chromatography (GC) system. A vespel/graphite ferrule based compression sealing technique is presented using which leak-proof fluidic interconnection between the inlet tubing and the microchannel was achieved. This sealing technique enabled separation at temperatures up to 350°C on a μGC column. This paper reports the first high-temperature separations in microfabricated chromatographic columns at these temperatures. A 2m microfabricated column using a double Archimedean spiral design with a square cross-section of 100μm×100μm has been developed using silicon microfabrication techniques. The microfabricated column was benchmarked against a 2m 100μm diameter commercial column and the performance between the two columns was evaluated in tests performed under identical conditions. High temperature separations of simulated distillation (ASTM2887) and polycyclic aromatic hydrocarbons (EPA8310) were performed using the μGC column in temperature programmed mode. The demonstrated μGC column along with the high temperature fixture offers one more solution toward potentially realizing a portable μGC device for the detection of semi-volatile environmental pollutants and explosives without the thermal limitations reported to date with μGC columns using epoxy based interconnect technology.

  4. Interpretative optimization of the isocratic ion chromatographic separation of anions

    Directory of Open Access Journals (Sweden)

    Todorović Žaklina N.


    Full Text Available Interpretive retention modeling was utilized to optimize the isocratic ion chromatographic (IC separation of the nine anions (formate, fluoride, chloride, nitrite, bromide, nitrate, phosphate, sulfate, oxalate. The carbonate-bicarbonate eluent was used and separation was done on a Dionex AS14 ion-exchange column. The influence of combined effects of two mobile phase factors, the total eluent concentration (2 - 6 mM and the carbonate/bicaronate ratio from 1:9 to 9:1 (which corespondent to pH range 9.35 - 11.27, on the IC separation was studied. The multiple species analyte/eluent model that takes into account ion-exchange equilibria of the eluent and sample anions was used. In order to estimate the parameters in the model, a non-linear fitting of the retention data, obtained at two-factor three-level experimental design, was applied. To find the optimal conditions in the experimental design, the normalized resolution product as a chromatographic objective function was employed. This criterion includes both the individual peak resolution and the total analysis time. A good agreement between experimental and simulated chromatograms was obtained. [Projekat Ministarstva nauke Republike Srbije, br. III43009

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

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


    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.

  6. JCE Feature Columns (United States)

    Holmes, Jon L.


    The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online ( know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad

  7. Evaluation of coverage, retention patterns, and selectivity of seven liquid chromatographic methods for metabolomics. (United States)

    Wernisch, Stefanie; Pennathur, Subramaniam


    Liquid chromatography-mass spectrometry-based metabolomics studies require highly selective and efficient chromatographic techniques. Typically employed reversed-phase (RP) methods fail to target polar metabolites, but the introduction of hydrophilic interaction liquid chromatography (HILIC) is slow due to perceived issues of reproducibility and ruggedness and a limited understanding of the complex retention mechanisms. In this study, we present a comparison of the chromatographic performance of a traditional RP-C18 column with zwitterionic, amide-, alkyl diol-, and aminoalkyl-based HILIC and mixed-mode columns. Our metabolite library represents one of the largest analyte sets available and consists of 764 authentic metabolite standards, including amino acids, nucleotides, sugars, and other metabolites, representing all major biological pathways and commonly observed exogenous metabolites (drugs). The coverage, retention patterns, and selectivity of the individual methods are highly diverse even between conceptually related HILIC methods. Furthermore, we show that HILIC sorbents having highly orthogonal selectivity and specificity enhance the coverage of major metabolite groups in (semi-) targeted applications compared to RP. Finally, we discuss issues encountered in the analysis of biological samples based on the results obtained with human plasma extracts. Our results demonstrate that fast and highly reproducible separations on zwitterionic columns are feasible, but knowledge of analyte properties is essential to avoid chromatographic bias and exclusion of key analytes in metabolomics studies. Graphical Abstract The chromatographic parameters of 764 authentic metabolite standards provide the basis for a comparison of coverage, selectivity and orthogonality of 7 reversed-phase (RP), mixed-mode (MM) and hydrophilic interaction liquid chromatography (HILIC) methods.

  8. High-performance liquid chromatographic separation of rolipram, bupivacaine and omeprazole using a tartardiamide-based stationary phase influence of flow rate and temperature on the enantioseparation. (United States)

    da Silva Junior, Ivanildo José; Sartor, João Paulo; Rosa, Paulo César Pires; de Veredas, Vinícius; Barreto Júnior, Amaro Gomes; Santana, Cesar Costapinto


    Chromatographic separation of the chiral drugs rolipram, bupivacaine and omeprazole on a tartardiamide-based stationary phase commercially named Kromasil CHI-TBB is shown in this work. The effect of temperature on the chromatographic separation of the chiral drugs using the Kromasil CHI-TBB stationary phase was determined quantitatively so as to contribute toward the design for the racemic mixtures of the named compound by using chiral columns. A decrease in the retention and selectivity factors was observed, when the column temperature increased. Van't Hoff plots provided the thermodynamic data. The variation of the thermodynamic parameters enthalpy and entropy are clearly negative meaning that the separation is enthalpy controlled.

  9. Flow rate dependent extra-column variance from injection in capillary liquid chromatography. (United States)

    Aggarwal, Pankaj; Liu, Kun; Sharma, Sonika; Lawson, John S; Dennis Tolley, H; Lee, Milton L


    Efficiency and resolution in capillary liquid chromatography (LC) can be significantly affected by extra-column band broadening, especially for isocratic separations. This is particularly a concern in evaluating column bed structure using non-retained test compounds. The band broadening due to an injector supplied with a commercially available capillary LC system was characterized from experimental measurements. The extra-column variance from the injection valve was found to have an extra-column contribution independent of the injection volume, showing an exponential dependence on flow rate. The overall extra-column variance from the injection valve was found to vary from 34 to 23 nL. A new mathematical model was derived that explains this exponential contribution of extra-column variance on chromatographic performance. The chromatographic efficiency was compromised by ∼130% for a non-retained analyte because of injection valve dead volume. The measured chromatographic efficiency was greatly improved when a new nano-flow pumping system with integrated injection valve was used.

  10. High-Performance Liquid Chromatographic-Tandem Mass Spectrometric Determination of Itraconazole in Human Plasma for Bioavailability and Bioequivalence Studies

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Young Wook; Nam, Dae Young; Kang, Kyoung Hoon; Ha, Kyung Wook; Han, In Hee; Chang, Byung Kon; Yoon, Mi Kyeong; Lee, Jae Hwi [Chung-Ang University, Seoul (Korea, Republic of)


    A highly sensitive high-performance liquid chromatographic-tandem mass spectrometric method (HPLC-MSMS) has been developed to quantify itraconazole in human plasma for the purpose of pharmacokinetic studies. Sample preparation was carried out by liquid-liquid extraction using loratadine as an internal standard. Chromatographic separation used a YMC C{sub 18} column, giving an extremely fast total run time of 3 min. The method was validated and used for the bioequivalence study of itraconazole tablets in healthy male volunteers (n = 31). The lower limit of detection proved to be 0.2 ng /mL for itraconazole.

  11. Uniform chromatographic conditions for quantifying urinary catecholamines, metanephrines, vanillylmandelic acid, 5-hydroxyindoleacetic acid, by liquid chromatography, with electrochemical detection. (United States)

    Parker, N C; Levtzow, C B; Wright, P W; Woodard, L L; Chapman, J F


    Uniform liquid-chromatographic conditions were developed such that we could quantify norepinephrine, epinephrine, normetanephrine, metanephrine, vanillylmandelic acid, and 5-hydroxyindoleacetic acid in urine by using a single mobile phase of monochloroacetic acid and citric acid, 0.1 mol/L each. All compounds were separated on a C18 column and detected electrochemically at a potential of +0.800 V. Optimization of these uniform chromatographic conditions significantly shortens the changeover time required from one assay to another, resulting in a substantial savings of time and cost to the laboratory.

  12. Chromatographic, Spectroscopic and Mass Spectrometric Approaches for Exploring the Habitability of Mars in 2012 and Beyond with the Curiosity Rover (United States)

    Mahaffy, Paul


    The Sample Analysis at Mars (SAM) suite of instruments on the Curiosity Rover of Mars Science Laboratory Mission is designed to provide chemical and isotopic analysis of organic and inorganic volatiles for both atmospheric and solid samples. The goals of the science investigation enabled by the gas chromatograph mass spectrometer and tunable laser spectrometer instruments of SAM are to work together with the other MSL investigations is to quantitatively assess habitability through a series of chemical and geological measurements. We describe the multi-column gas chromatograph system employed on SAM and the approach to extraction and analysis of organic compounds that might be preserved in ancient martian rocks.

  13. Liquid chromatographic analysis of oxytocin and its related substances. (United States)

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


    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.

  14. Gas chromatographic validated method for quantification of ayurvedic polyherbal formulation

    Directory of Open Access Journals (Sweden)

    Navdeep Saini


    Full Text Available A new gas chromatographic-flame ionization detector (GC-FID method was developed for quantification of ayurvedic polyherbal formulation. The GC-FID method was found highly accurate, sensitive, simple and precise. This method was validated as per international conference on harmonization (ICH guidelines. Experimental work was performed by nonpolar capillary column (Zb-5, 5%-Phenyl-95%-dimethylpolysiloxane. Film thickness of capillary column (Zb-5 was (0.25 μm and length 30 m × 0.25 mm i.d. The temperature of the oven, injector and detector were 200, 210 and 280°C respectively. Data processing system was applied to obtain data. The standards and test samples were prepared in absolute ethanol. The principle constituents t-Anethol, d-Limonene, cuminaldehyde and thymol were found in ayurvedic polyherbal formulation. The ICH validation parameters for the proposed procedure, recovery (limit 98.85-100.76%, precision (<1.00%, limits of detection, limits of quantification and linearity (r2 = 0.995 ± 0.002 were observed under acceptance limit. Validation results were statistically calculated. The result shows that method is selective and reproducible for quantification of ayurvedic polyherbal formulation. The presented GC method can be applied for the routine analysis of principle constituents as well as ayurvedic polyherbal formulation.

  15. Liquid chromatographic determination of beta-naphthoxyacetic acid in tomatoes. (United States)

    Gökmen, V; Acar, J


    An alternative high-performance liquid chromatographic method for the determination of beta-naphthoxyacetic acid (BNOA) in tomatoes is described. BNOA was extracted from tomatoes with acetone-dichloromethane (2:1). The extract was cleaned up by Bio-Beads S-X3 gel-permeation chromatography and by partitioning. A reversed-phase C18 column was used for HPLC analysis. The mobile phase was acetonitrile-2% acetic acid in water (50:50, v/v) pumped at a flow-rate of 1.0 ml/min. Retention time of BNOA was ca. 7 min with a percentage coefficient of variation of 0.71. Resolution of BNOA was good on the column. Percentage recoveries of BNOA were 79.5 +/- 6.82, 94.8 +/- 2.70 and 86.4 +/- 16.43 for the corresponding spiking levels of 0.5, 1.0 and 2.0 micrograms per g tomato, respectively. Analysis of 10 greenhouse tomato samples from local markets in Ankara showed no BNOA residue.

  16. Gas chromatograph-combustion system for 14C-accelerator mass spectrometry. (United States)

    McIntyre, Cameron P; Sylva, Sean P; Roberts, Mark L


    A gas chromatograph-combustion (GC-C) system is described for the introduction of samples as CO(2) gas into a (14)C accelerator mass spectrometry (AMS) system with a microwave-plasma gas ion source. Samples are injected into a gas chromatograph fitted with a megabore capillary column that uses H(2) as the carrier gas. The gas stream from the outlet of the column is mixed with O(2) and Ar gas and passed through a combustion furnace where the H(2) carrier gas and separated components are quantitatively oxidized to CO(2) and H(2)O. Water vapor is removed using a heated nafion dryer. The Ar carries the CO(2) to the ion source. The system is able to separate and oxidize up to 10 microg of compound and transfer the products from 7.6 mL/min of H(2) carrier gas into 0.2-1.0 mL/min of Ar carrier gas. Chromatographic performance and isotopic fidelity satisfy the requirements of the (14)C-AMS system for natural abundance measurements. The system is a significant technical advance for GC-AMS and may be capable of providing an increase in sensitivity for other analytical systems such as an isotope-ratio-monitoring GC/MS.

  17. Preparation of macroporous methacrylate-based monoliths for chromatographic applications by the Reactive Gelation Process. (United States)

    Bechtle, M; Butté, A; Storti, G; Morbidelli, M


    Polymeric monoliths are a relatively new separation medium for chromatographic applications. The innovative approach to produce such monoliths, the Reactive Gelation Process, presented by Marti et al. [1] for polystyrene macroporous materials is applied to a methacrylate-based material. It is shown that it is possible to create a macroporous structure by Reactive Gelation also with this polymer even if the properties of the material are different. Besides the analysis of the material by SEM and BET, several chromatographic methods are used to analyze the material properties. The ISEC experiments showed a much smaller size exclusion effect than in conventional packed beds. The permeability of the material is comparable to a packed bed with 4.13 μm particles. The column efficiency is not changing for increasing flow rates. Because of the high efficiency of the material, shorter columns are needed and therefore the comparatively low permeability is compensated. The monolith also exhibits a significant adsorption capacity for hydrophobic interaction, which makes it suitable for chromatographic purification processes.

  18. Simple and rapid gas-liquid-solid chromatographic analysis of trace concentrations of acetaldehyde in urban air. (United States)

    Hoshika, Y


    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.

  19. Chromatographic Separation of Glucose and Fructose (United States)

    Kuptsevich, Yu E.; Larionov, Oleg G.; Stal'naya, I. D.; Nakhapetyan, L. A.; Pronin, A. Ya


    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.

  20. Eruption column physics

    Energy Technology Data Exchange (ETDEWEB)

    Valentine, G.A.


    In this paper the author focuses on the fluid dynamics of large-scale eruption columns. The dynamics of these columns are rooted in multiphase flow phenomena, so a major part of the paper sets up a foundation on that topic that allows one to quickly assess the inherent assumptions made in various theoretical and experimental approaches. The first part is centered on a set of complex differential equations that describe eruption columns, but the focus is on a general understanding of important physical processes rather than on the mathematics. The author discusses briefly the relative merits and weaknesses of different approaches, emphasizing that the largest advances in understanding are made by combining them. He then focuses on dynamics of steady eruption columns and then on transient phenomena. Finally he briefly reviews the effects of varying behavior of the ambient medium through which an eruption column moves. These final sections will emphasize concepts and a qualitative understanding of eruption dynamics. This paper relies on principles of continuum mechanics and transport processes but does not go into detail on the development of those principles. 36 refs., 36 figs., 3 tabs.

  1. A low-power pressure-and temperature-programmed separation system for a micro gas chromatograph.

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, Richard D. (University of Michigan, Ann Arbor, MI); Robinson, Alex Lockwood (Advanced Sensor Technologies, Albuquerque, NM); Lambertus, Gordon R. (University of Michigan, Ann Arbor, MI); Potkay, Joseph A. (University of Michigan, Ann Arbor, MI); Wise, Kensall D. (University of Michigan, Ann Arbor, MI)


    This thesis presents the theory, design, fabrication and testing of the microvalves and columns necessary in a pressure- and temperature-programmed micro gas chromatograph ({micro}GC). Two microcolumn designs are investigated: a bonded Si-glass column having a rectangular cross section and a vapor-deposited silicon oxynitride (Sion) column having a roughly circular cross section. Both microcolumns contain integrated heaters and sensors for rapid, controlled heating. The 3.2 cm x 3.2 cm, 3 m-long silicon-glass column, coated with a non-polar polydimethylsiloxane (PDMS) stationary phase, separates 30 volatile organic compounds (VOCs) in less than 6 min. This is the most efficient micromachined column reported to date, producing greater than 4000 plates/m. The 2.7 mm x 1.4 mm Sion column eliminates the glass sealing plate and silicon substrate using deposited dielectrics and is the lowest power and fastest GC column reported to date; it requires only 11 mW to raise the column temperature by 100 C and has a response time of 11s and natural temperature ramp rate of 580 C/min. A 1 m-long PDMS-coated Sion microcolumn separates 10 VOCs in 52s. A system-based design approach was used for both columns.

  2. Chromatographic fingerprint analysis of yohimbe bark and related dietary supplements using UHPLC/UV/MS. (United States)

    Sun, Jianghao; Chen, Pei


    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.

  3. Comparison among three anion exchange chromatographic supports to capture erythropoietin from cell culture supernatant

    Institute of Scientific and Technical Information of China (English)



    Affinity and ion exchange conventional chromatography have been used to capture erythropoietin ( EPO)from mammalian cell culture supernatant. Currently,chromatographic adsorbent perfusion is available, however a limited number of applications have been found in the literature. In this work,three anion exchange chromatographic supports( gel,membrane and monolithic)were evaluated in the capture step of the recombi-nant erythropoietin purification process. The influences of load and flow rate on each support performance were analyzed. Also the purity of the EPO molecules was determined. A productivity analysis,as a decision tool for larger scale implementation,was done. As a conclusion,the evaluated supports are technically suitable to cap-ture EPO with adequate recovery and good purity. However,the monolithic column admits high operating velocity,showing the highest adsorption capacity and productivity.

  4. Simultaneous liquid-chromatographic determination of urinary vanillylmandelic acid, homovanillic acid, and 5-hydroxyindoleacetic acid. (United States)

    Gironi, A; Seghieri, G; Niccolai, M; Mammini, P


    We describe a liquid-chromatographic method for quantifying, simultaneously by a single procedure, vanillylmandelic acid (VMA), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in urine. After solvent extraction of acidified urine, the analytes were chromatographed on a C8 column, with use of a mobile phase of phosphate buffer (20 mmol/L, pH 4.0) and methanol with a variable gradient elution, and detected fluorometrically. We report the analytical recovery, sensitivity, precision, working linear range, and potential for interference from similar molecules or drugs. The results of such tests demonstrate that the proposed method is sensitive and reproducible. It is, furthermore, easy to perform, and thus is suitable for use in the clinical laboratory.

  5. Robust naphthyl methacrylate monolithic column for high performance liquid chromatography of a wide range of solutes. (United States)

    Jonnada, Murthy; El Rassi, Ziad


    An organic monolithic column based on the co-polymerization of 2-naphthyl methacrylate (NAPM) as the functional monomer and trimethylolpropane trimethacrylate (TRIM) as the crosslinker was introduced for high performance reversed-phase liquid chromatography (RPC). The co-polymerization was performed in situ in a stainless steel column of 4.6mm i.d. in the presence of a ternary porogen consisting of 1-dodecanol and cyclohexanol. This monolithic column (referred to as naphthyl methacrylate monolithic column or NMM column) showed high mechanical stability at relatively high mobile phase flow velocity indicating that the column has excellent hydrodynamic characteristics. To characterize the NMM column, different probe molecules including alkyl benzenes, and aniline, benzene, toluene and phenol derivatives were chromatographed on the column and the results in terms of k, selectivity and plate counts were compared to those obtained on an octadecyl silica (ODS) column in order to assess the presence of π-π and hydrophobic interactions on the NMM column under otherwise the same elution conditions. The NMM column offered additional π-π interactions with aromatic molecules in addition to hydrophobic interactions under RPC elution conditions. Run-to-run and column-to-column reproducibility of solute k values were evaluated, and percent relative standard deviation of column using shallow (30min at 1.0mL/min), steep (10min at 1.0mL/min) and ultra steep (1min at 3.0mL/min) linear gradient elution at increasing ACN concentration in the mobile phase using a 10cm×4.6mm i.d. column in case of shallow and steep linear gradients and a 3cm×4.6mm i.d. column for ultra steep linear gradient.

  6. Monolithic columns in plant proteomics and metabolomics. (United States)

    Rigobello-Masini, Marilda; Penteado, José Carlos Pires; Masini, Jorge Cesar


    Since "omics" techniques emerged, plant studies, from biochemistry to ecology, have become more comprehensive. Plant proteomics and metabolomics enable the construction of databases that, with the help of genomics and informatics, show the data obtained as a system. Thus, all the constituents of the system can be seen with their interactions in both space and time. For instance, perturbations in a plant ecosystem as a consequence of application of herbicides or exposure to pollutants can be predicted by using information gathered from these databases. Analytical chemistry has been involved in this scientific evolution. Proteomics and metabolomics are emerging fields that require separation, identification, and quantification of proteins, peptides, and small molecules of metabolites in complex biological samples. The success of this work relies on efficient chromatographic and electrophoretic techniques, and on mass spectrometric detection. This paper reviews recent developments in the use of monolithic columns, focusing on their applications in "top-down" and "bottom-up" approaches, including their use as supports for immobilization of proteolytic enzymes and their use in two-dimensional and multidimensional chromatography. Whereas polymeric columns have been predominantly used for separation of proteins and polypeptides, silica-based monoliths have been more extensively used for separation of small molecules of metabolites. Representative applications in proteomics and in analysis of plant metabolites are given and summarized in tables.

  7. Extraction chromatographic separation of Am(III) and Eu(III) by TPEN-immobilized gel

    Energy Technology Data Exchange (ETDEWEB)

    Takeshita, K. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 157-8550 (Japan); Ogata, T.; Oaki, H.; Inaba, Y. [Solutions Research Organization, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan); Mori, A. [Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Yaita, T. [Tokai Research and Development Center, Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaragi 319-1195 (Japan); Koyama, S.I. [Oarai Research and Development Center, Japan Atomic Energy Agency. 4002 Narita, Oarai-cho, Ibaraki 311-1393 (Japan)


    A TPEN derivative with 4 vinyl groups, N,N,N',N' -tetrakis-(4-propenyloxy-2-pyridylmethyl)ethylenediamine (TPPEN) was synthesized for the separation of trivalent minor actinides (Am(III)) and lanthanides (Eu(III)). A co-polymer gel with TPPEN and N-isopropylacrylamide (NIPA) showed a high separation factor of Am(III) over Eu(III) (SF[Am/Eu]), which was evaluated to be 26 at pH=5. Thin film of NIPA-TPPEN gel (average thickness: 2-40 nm) was immobilized on the pore surface in porous silica particles (particle diameter : 50 μm, average pore diameter : 50 and 300 nm) and a chromatographic column (diameter: 6 mm, height: 11 mm) packed with the gel-coated particles was prepared. A small amount of weakly acidic solution (pH=4) containing Am(III) and Eu(III) was supplied in the column and the elution tests of Am(III) and Eu(III) were carried out. Eu(III) was recovered separately by a weakly acidic eluent (pH=4) at 313 K and Am(III) by a highly acidic eluent (pH=2) at 298 K. These results suggest that the contentious separation of minor actinides and lanthanides is attainable by a new extraction chromatographic process with two columns adjusted to 298 K and 313 K. (authors)

  8. Fully automated high-performance liquid chromatographic assay for the analysis of free catecholamines in urine. (United States)

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


    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%.

  9. Functional chromatographic technique for natural product isolation†


    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


    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.

  10. Chromatographic methods in the study of autism. (United States)

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


    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.

  11. 40 CFR 1065.267 - Gas chromatograph. (United States)


    ... 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...

  12. Cyclic electrophoretic and chromatographic separation methods

    NARCIS (Netherlands)

    Eijkel, Jan C.T.; Berg, van den Albert; Manz, Andreas


    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† (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.


    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

  14. Chromatography on DEAE ion-exchange and Protein G affinity columns in tandem for the separation and purification of proteins. (United States)

    Qi, Y; Yan, Z; Huang, J


    A high-performance liquid-chromatographic method based on coupled DEAE anion-exchange and Protein G affinity columns has been developed for the simultaneous separation and purification of immunoglobulin G and albumin from mouse serum. The diluted mouse serum was injected directly into this system, and the proteins were eluted separately from the DEAE and Protein G columns, coupled in series, by the column-switching technique. The advantages of this method are that IgG and albumin can be separated and purified simultaneously, the expensive affinity column is protected from contamination by the impurities in the mouse serum, and it is fast, selective, robust, and reproducible.

  15. Hydrodynamic impact of particle shape in slurry packed liquid chromatography columns

    DEFF Research Database (Denmark)

    Lottes, F.; Arlt, W.; Minceva, M.;


    We report on a series of flow velocity and efficiency profiles, which were measured across the cross section of preparative chromatographic columns packed with different stationary phase materials using computed tomography. It is shown that this non-invasive technique is very useful for visualiza......We report on a series of flow velocity and efficiency profiles, which were measured across the cross section of preparative chromatographic columns packed with different stationary phase materials using computed tomography. It is shown that this non-invasive technique is very useful...... for visualization of the inner part of a packed column and measurement of the spatial resolved column packing properties. For evaluation of the influence of the particle shape on the velocity distribution and column performance, irregular and spherical reversed phases were studied in detail. The results showed...... a decreasing velocity towards the column wall most certainly due to a lower permeability. This effect was much less pronounced in the case of spherical particles, indicating a more homogenous packing structure. The influence of the column packing pressure, as a possible measure for improvement of the packing...

  16. Slender CRC Columns

    DEFF Research Database (Denmark)

    Aarup, Bendt; Jensen, Lars Rom; Ellegaard, Peter


    CRC is a high-performance steel fibre reinforced concrete with a typical compressive strength of 150 MPa. Design methods for a number of structural elements have been developed since CRC was invented in 1986, but the current project set out to further investigate the range of columns for which...

  17. Columns in Clay (United States)

    Leenhouts, Robin


    This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

  18. Isolation of flavonoids from Aleurites moluccana using chitosan modified with benzaldehyde (CH-Bz) as chromatographic support. (United States)

    Girardi, L G J; Morsch, M; Cechinel-Filho, V; Meyre-Silva, C; Rodrigues, C A


    This paper describes the preparation, characterization and use of a derivative of chitosan as a chromatographic sorbent. Chitosan modified with benzenic ring (CH-Bz) was used to separate two flavonoids, swertisin and 2"-O-rhamnosylswertisin, from ethyl acetate fraction of Aleurites moluccana. The results showed that CH-Bz can be used as a sorbent for the separation of flavonoid compounds. The studies showed that CH-Bz in column chromatography produces goods results, separation of the flavonoid compounds.

  19. Chromatographic determination of flumequine in food samples by post-column derivatisation with terbium(III)

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Diaz, R.C. [Department of Analytical Chemistry, ' Marie Curie Annex' Building, Campus of Rabanales, University of Cordoba, E-14071 Cordoba (Spain); Fernandez-Romero, J.M. [Department of Analytical Chemistry, ' Marie Curie Annex' Building, Campus of Rabanales, University of Cordoba, E-14071 Cordoba (Spain); Aguilar-Caballos, M.P. [Department of Analytical Chemistry, ' Marie Curie Annex' Building, Campus of Rabanales, University of Cordoba, E-14071 Cordoba (Spain); Gomez-Hens, A. [Department of Analytical Chemistry, ' Marie Curie Annex' Building, Campus of Rabanales, University of Cordoba, E-14071 Cordoba (Spain)]. E-mail:


    The potential usefulness of terbium(III) as reagent for the luminescent determination of flumequine residues in food samples has been studied using both fluorescence (FL) and time-resolved (TR) modes and both batch (B) and integrated liquid chromatography (LC)/derivatisation approaches. The system was optimised in each instance to establish the analytical features of the four methods. The dynamic ranges of the calibration graphs, obtained with standard solutions of flumequine, were (ng mL{sup -1}): B-FL 0.18-600; B-TR 2.4-150; LC-FL 3.7-1000 and LC-TR 52-3000. The detection limits were also obtained giving the following values (ng mL{sup -1}): B-FL 0.055; B-TR 0.7; LC-FL 1.1 and LC-TR 15. The precision, expressed as the percentage of relative standard deviation, was equal or lower than 5.1% in all instances. The LC methods, which avoid the interference of other quinolone antibiotics, were applied to the analysis of chicken muscle and liver, and whole milk samples. The sample pre-treatment only consisted of a deproteinisation step. The validation procedure for the analysis of samples was carried out using EC recommendations, and the decision limit and detection capability were calculated. The recoveries obtained ranged from 95.0% to 103.8%.


    Interest in possible sources of perchlorate (ClO4-) that could lead to environmental release has been heightened since the EPA placed this anion on its Contaminant Candidate List (CCL) for drinking water. Besides its association with defense and aerospace activities, perchlorate ...

  1. A new method for high-performance liquid chromatographic determination of drotaverine in plasma. (United States)

    Mezei, J; Küttel, S; Szentmiklósi, P; Marton, S; Rácz, I


    A sensitive, specific high-performance liquid chromatographic procedure was developed for the determination of plasma drotaverine levels. Basic plasma samples were adjusted to pH 1.5 and extracted with chloroform. HPLC [n-heptane-dichloromethane-diethylamine (50:25:2)] on a microporous silica column, with a variable-wavelength UV detector set at 302 nm allowed the measurement of drotaverine at the 50-ng/mL level. The utility of this method for determination of drotaverine in dog and rat plasma was demonstrated.

  2. Chromatographic Separations Using Solid-Phase Extraction Cartridges: Separation of Wine Phenolics (United States)

    Brenneman, Charles A.; Ebeler, Susan E.


    We describe a simple laboratory experiment that demonstrates the principles of chromatographic separation using solid-phase extraction columns and red wine. By adjusting pH and mobile phase composition, the wine is separated into three fractions of differing polarity. The content of each fraction can be monitored by UV-vis spectroscopy. When the experiment is combined with experiments involving HPLC or GC separations, students gain a greater appreciation for and understanding of the highly automated instrumental systems currently available. In addition, they learn about the chemistry of polyphenolic compounds, which are present in many foods and beverages and which are receiving much attention for their potentially beneficial health effects.

  3. Chromatographic air analyser microsystem for the selective and sensitive detection of atmospheric pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Jean-Baptiste; Lahlou, Houda; Mohsen, Yehya; Berger, Franck [Laboratoire de Chimie Physique et Rayonnements, Alain Chambaudet, UMR CEA E4 UFR ST, Universite de Franche Comte, 25000 Besancon (France); Vilanova, Xavier; Correig, Xavier, E-mail: [Departament d' Enginyeria Electronica, Electrica i Automatica, Universitat Rovira i Virgili, Paisos Catalans 26, 43007, Tarragona (Spain)


    The development of industry and automotive trafic produces Volatile Organic Compounds (VOCs) whose toxicity can affect seriously human health and environment. The level of those contaminants in air must be as low as possible. In this context, there is a need for in situ systems that could monitor selectively the concentration of these compounds. The aim of this study is to demonstrate the efficiency of a system build with a pre-concentrator, a chromatographic micro-column and a tin oxide-based gas sensor for the selective and sensitive detection of atmospheric pollutants. In particular, this study is focused on the selective detection of benzene and 1,3 butadiene.

  4. Controlled oxidative protein refolding using an ion-exchange column. (United States)

    Langenhof, Marc; Leong, Susanna S J; Pattenden, Leonard K; Middelberg, Anton P J


    Column-based refolding of complex and highly disulfide-bonded proteins simplifies protein renaturation at both preparative and process scale by integrating and automating a number of operations commonly used in dilution refolding. Bovine serum albumin (BSA) was used as a model protein for refolding and oxido-shuffling on an ion-exchange column to give a refolding yield of 55% after 40 h incubation. Successful on-column refolding was conducted at protein concentrations of up to 10 mg/ml and refolded protein, purified from misfolded forms, was eluted directly from the column at a concentration of 3 mg/ml. This technique integrates the dithiothreitol removal, refolding, concentration and purification steps, achieving a high level of process simplification and automation, and a significant saving in reagent costs when scaled. Importantly, the current result suggests that it is possible to controllably refold disulfide-bonded proteins using common and inexpensive matrices, and that it is not always necessary to control protein-surface interactions using affinity tags and expensive chromatographic matrices. Moreover, it is possible to strictly control the oxidative refolding environment once denatured protein is bound to the ion-exchange column, thus allowing precisely controlled oxido-shuffling.

  5. Determination of urinary vanillylmandelic acid by direct injection and coupled-column chromatography with electrochemical detection. (United States)

    Eriksson, B M; Persson, B A; Wikström, M


    An automated column-switching system for determination of vanillylmandelic acid in urine is described. The liquid chromatographic system was composed of two separation columns with different selectivity properties, an octadecyl column coated with tributyl phosphate as stationary liquid phase and a silica-based anion exchanger. Urine samples were injected directly onto the first column, where vanillylmandelic acid was separated from the main part of the sample matrix. The internal standard isovanillylmandelic acid was co-eluting with vanillylmandelic acid, and a fraction of the eluate containing both substances was switched to the second column, where separation was performed. To assess peak purity, detection was performed with dual working electrodes in parallel mode. A relative standard deviation of 3.5% was obtained for determination of human urine samples containing 3 microM vanillylmandelic acid, and less than 0.1 microM could be detected.

  6. Exogenous factors contributing to column bed heterogeneity: Part 1: Consequences of 'air' injections in liquid chromatography. (United States)

    Samuelsson, Jörgen; Fornstedt, Torgny; Shalliker, Andrew


    It has been shown that not only the packing homogeneity, but also factors external to the column bed, such as, frits and distributors can have important effects on the column performance. This current communication is the first in a series focusing on the impact of exogenous factors on the column bed heterogeneity. This study is based on several observations by us and others that chromatographic runs often, for technical reasons, include more or less portions of air in the injections. It is therefore extremely important to find out the impact of air on the column performance, the reliability of the results derived from analyses where air was injected, and the effect on the column homogeneity. We used a photographic approach for visualising the air transport phenomena, and found that the air transport through the column is comprised of many different types of transport phenomena, such as laminal flow, viscous fingering like flows, channels and bulbs, and pulsations. More particularly, the air clouds within the column definitely interact in the adsorption, i.e. mobile phase adsorbed to the column surface is displaced. In addition, irrespective of the type of air transport phenomena, the air does not penetrate the column homogeneously. This process is strongly flow dependent. In this work we study air transport both in an analytical scale and a semi-prep column.

  7. Surface modification of polytetrafluoroethylene column for two-stationary phase separations by counter-current chromatography. (United States)

    Quan, Kai-jun; Huang, Xin-yi; Li, Xiao-ting; Wang, Gao-hong; Liu, Yan-juan; Duan, Wen-da; Di, Duo-long


    To improve the separation capability of CCC, a novel solid-liquid two-stationary phases CCC (ASP-CCC) column was prepared employing graphene oxide (GO) conjugated poly-dopamine (PD) coating (GO/PD) as auxiliary stationary phase (ASP). The results of Scanning electron microscopy (SEM), contact angle and X-ray photoelectron spectroscopy (XPS) indicated that nanostructured GO and PD were successfully grafted on the inner wall of the PTFE column. Three alkaloid compounds were selected as the target analytes to evaluate the performance of the novel column. Because of the intermolecular force (hydrogen bond, electrostatic interaction and π-π interaction) between the ASP and model compounds, three analytes were well separated with this novel ASP-CCC column. Additionally, the novel column exhibited higher stationary phase retention ratio, about 8%, than original column without changing the chromatographic condition. Furthermore, the eluotropic sequence of analytes on novel column was in accordance with that in the original column. This suggested that the novel column is a CCC column with auxiliary stationary phase (ASP) in its own right, and the present separation mode is the combination of partition chromatography and adsorption chromatography.

  8. Derringer desirability and kinetic plot LC-column comparison approach for MS-compatible lipopeptide analysis

    Directory of Open Access Journals (Sweden)

    Matthias D’Hondt


    In total, the performance of four different C18 columns, including one UPLC column, were evaluated using two parallel approaches. First, a Derringer desirability function was used, whereby six single and multiple chromatographic response values were rescaled into one overall D-value per column. Using this approach, the YMC Pack Pro C18 column was ranked as the best column for general MS-compatible lipopeptide separation. Secondly, the kinetic plot approach was used to compare the different columns at different flow rate ranges. As the optimal kinetic column performance is obtained at its maximal pressure, the length elongation factor λ (Pmax/Pexp was used to transform the obtained experimental data (retention times and peak capacities and construct kinetic performance limit (KPL curves, allowing a direct visual and unbiased comparison of the selected columns, whereby the YMC Triart C18 UPLC and ACE C18 columns performed as best. Finally, differences in column performance and the (disadvantages of both approaches are discussed.

  9. Slurry bubble column hydrodynamics (United States)

    Rados, Novica

    Slurry bubble column reactors are presently used for a wide range of reactions in both chemical and biochemical industry. The successful design and scale up of slurry bubble column reactors require a complete understanding of multiphase fluid dynamics, i.e. phase mixing, heat and mass transport characteristics. The primary objective of this thesis is to improve presently limited understanding of the gas-liquid-solid slurry bubble column hydrodynamics. The effect of superficial gas velocity (8 to 45 cm/s), pressure (0.1 to 1.0 MPa) and solids loading (20 and 35 wt.%) on the time-averaged solids velocity and turbulent parameter profiles has been studied using Computer Automated Radioactive Particle Tracking (CARPT). To accomplish this, CARPT technique has been significantly improved for the measurements in highly attenuating systems, such as high pressure, high solids loading stainless steel slurry bubble column. At a similar set of operational conditions time-averaged gas and solids holdup profiles have been evaluated using the developed Computed Tomography (CT)/Overall gas holdup procedure. This procedure is based on the combination of the CT scans and the overall gas holdup measurements. The procedure assumes constant solids loading in the radial direction and axially invariant cross-sectionally averaged gas holdup. The obtained experimental holdup, velocity and turbulent parameters data are correlated and compared with the existing low superficial gas velocities and atmospheric pressure CARPT/CT gas-liquid and gas-liquid-solid slurry data. The obtained solids axial velocity radial profiles are compared with the predictions of the one dimensional (1-D) liquid/slurry recirculation phenomenological model. The obtained solids loading axial profiles are compared with the predictions of the Sedimentation and Dispersion Model (SDM). The overall gas holdup values, gas holdup radial profiles, solids loading axial profiles, solids axial velocity radial profiles and solids

  10. Chromatographic fingerprint analysis of Pycnogenol dietary supplements. (United States)

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


    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. Chromatographic separation of low-temperature tar. Part III

    Energy Technology Data Exchange (ETDEWEB)

    Terres, E.; Gebert, F.; Huelsemann, H.; Petereit, H.; Toepsch, H.; Ruppert, W.


    Experiments with crude phenolic mixtures in benzene-MeOH over an alumina chromatographic column are reported. The most effective separation into crude fractions was obtained from a petroleum-ether solution with benzene and benzene-MeOH elution. These fractions are analyzed by paper chromatography. R/sub f/ values for 29 phenols and benzoic acid from water-saturated AmOH are given. Folin-Denis reagent and ultraviolet absorption is used for identification of the phenolic compounds. R/sub f/ values for monohydroxy compounds are larger than 0.9, dihydroxy 0.80 to 0.9, trihydroxy 0.6, hydroxytoluic acids 0.39 to 0.56. R/sub f/ values of Na and K salts are different from those of the free phenols. Tests in aqueous solution near 0/sup 0/ gave important results. R/sub f/ values of the less polar materials decrease and less material is lost through evaporation, smaller and sharper spots are obtained and liquids move at a more even rate. A series of isomeric alkyl phenols is reported; ortho alkyl groups decrease the migration rate most effectively.

  12. Liquid chromatographic determination of sennosides in Cassia angustifolia leaves. (United States)

    Srivastava, Alpuna; Pandey, Richa; Verma, Ram K; Gupta, Madan M


    A simple liquid chromatographic method was developed for the determination of sennosides B and A in leaves of Cassia angustifolia. These compounds were extracted from leaves with a mixture of methanol-water (70 + 30, v/v) after defatting with hexane. Analyte separation and quantitation were achieved by gradient reversed-phase liquid chromatography and UV absorbance at 270 nm using a photodiode array detector. The method involves the use of an RP-18 Lichrocart reversed-phase column (5 microm, 125 x 4.0 mm id) and a binary gradient mobile-phase profile. The various other aspects of analysis, namely, peak purity, similarity, recovery, repeatability, and robustness, were validated. Average recoveries of 98.5 and 98.6%, with a coefficient of variation of 0.8 and 0.3%, were obtained by spiking sample solution with 3 different concentration solutions of standards (60, 100, and 200 microg/mL). Detection limits were 10 microg/mL for sennoside B and 35 microg/mL for sennoside A, present in the sample solution. The quantitation limits were 28 and 100 microg/mL. The analytical method was applied to a large number of senna leaf samples. The new method provides a reliable tool for rapid screening of C. angustifolia samples in large numbers, which is needed in breeding/genetic engineering and genetic mapping experiments.

  13. Selective determination of ammonium ions by high-speed ion-exclusion chromatography on a weakly basic anion-exchange resin column. (United States)

    Mori, Masanobu; Tanaka, Kazuhiko; Helaleh, Murad I H; Xu, Qun; Ikedo, Mikaru; Ogura, Yutaka; Sato, Shinji; Hu, Wenzhi; Hasebe, Kiyoshi


    This paper describes an ion-exclusion chromatographic system for the rapid and selective determination of ammonium ion. The optimized ion-exclusion chromatographic system was established with a polymethacrylate-based weakly basic anion-exchange resin column (TSKgel DEAE-5PW) as the separation column, an aqueous solution containing 0.05 mM tetramethylammonium hydroxide (pH 9.10) as eluent with conductimetric detection for the analyte determination. Under the optimum chromatographic conditions, ammonium ion was determined within 2.3 min with a detection limit (S/N=3) better than 0.125 microM. Ammonium ion in rain and river waters was precisely determined using this ion-exclusion chromatographic system.

  14. [Effect of emulsion on chromatographic process]. (United States)

    Jiang, Yulei; Li, Xi


    The types and features of concentration wave of the chromatographic process in which the mobile phase was emulsion were studied theoretically by the method of characteristics and the concept of multi mobile phase chromatography. When the mobile phase is an emulsion, solute is partitioned between the inner and outer phases of the emulsion as well as simultaneously adsorbed on the stationary phase resulting in the great difference of concentration profiles from the case in which the mobile phase is homogenous. The various profiles and mechanisms of concentration wave of the chromatographic process in which the partition relationship between the inner and outer phases of the emulsion and the adsorption isotherm on the stationary phase were both Langmuir-like were analyzed and discussed with corresponding examples, and the comparison with the case in which the mobile phase is homogenous is also done. It is shown that the chromatographic progress with emulsion is more complicated and multiple. The existence of multi mobile phases may sharpen simple wave to be shock wave or diffuse shock wave to be simple wave.

  15. Behavior of Columns During Earthquakes (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The behavior of columns during earthquakes is very important since column failures may lead to additional structural failures and result in total building collapses....

  16. Determination of Two Columns Performance

    Institute of Scientific and Technical Information of China (English)


    When protein is analyzed by high performance liquid chromatography (HPLC), the selection of column is one of the most important factors. There are four quality control parameters for the column, which are theoretical plates n, capacity facto

  17. NMFS Water Column Sonar Database (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water column sonar data are an important component of fishery independent surveys, habitat studies and other research. NMFS water column sonar data are archived here.

  18. In situ sol-gel preparation of porous alumina monoliths for chromatographic separations of adenosine phosphates. (United States)

    Zajickova, Zuzana; Rubi, Emir; Svec, Frantisek


    A method enabling the in situ preparation of porous alumina monoliths within 100 μm i.d. fused silica capillaries has been developed. These monoliths were prepared using the sol-gel process from a mixture consisting of an inorganic aluminum salt, a porogen, an epoxide, and a solvent. We investigated the effects of varying the preparation conditions on the physical characteristics of the monoliths with respect to their potential application in chromatographic separations. The best columns were obtained from a mixture of aluminum chloride hexahydrate, N,N-dimethylformamide, water, ethanol and propylene oxide. Adenosine phosphates were then separated in the optimized column with retention increasing according to number of phosphate functionalities.

  19. A new chromatographic-method for fast separation of active proteins

    Institute of Scientific and Technical Information of China (English)

    KE CongYu; GENG XinDu


    A new method with only a single chromatographic column to accomplish the separation of intact pro-tein molecules by the combination of ion exchange chromatography and hydrophobic interaction chromatography is firstly presented. By selecting twice a suitable stationary phase, mobile phase, buffer exchange condition, and sample injection, some proteins usually required to separate with two-dimensional chromatography can now be accomplished only using the single column in one hour. In addition, the separated proteins can maintain their original three- or four-dimensional molecular structure. It would be expected that this method can also provide a new thought for sample pre-frac-tionation in proteomic investigation, especially, for the limitation of sample source.

  20. First Results From the Gas Chromatograph Mass Spectrometer (GCMS) Experiment on the Cassini-Huygens Probe (United States)

    Niemann, Hasso B.; Demick, J.; Haberman, J.; Harpold, D.; Kasprzak, W.; Raaen, E.; Way, S.; Atreya, S.; Carignan, G.; Bauer, S.


    The Huygens Probe of the Cassini Huygens Mission entered the atmosphere of the moon Titan on January 14,2005. The GCMS was part of the instrument complement on the Probe to measure in situ the chemical composition of the atmosphere during the probe descent and to support the Aerosol Collector Pyrolyser (ACP) experiment by serving as detector for the pyrolization products. The GCMS employed a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns. The mass spectrometer employed five electron impact ion sources with available electron energies of either 70 or 25 eV. Three ion sources served as detectors for the GC columns and two were dedicated to direct atmosphere sampling and ACP gas sampling, respectively. The GCMS gas inlet was heated to prevent condensation, and served to evaporate surface constituents after impact.

  1. Chromatographic separation of vanadium, tungsten and molybdenum with a liquid anion-exchanger. (United States)

    Fritz, J S; Topping, J J


    In acidic solution only molybdenum(VI), tungsten(VI), vanadium(V), niobium(V) and tantalum(V) form stable, anionic complexes with dilute hydrogen peroxide. This fact has been used in developing an analytical method of separating molybdenum(VI), tungsten(VI) and vanadium(V) from other metal ions and from each other. Preliminary investigations using reversed-phase paper chromatography and solvent extraction led to a reversed-phase column Chromatographic separation technique. These metal-peroxy anions are retained by a column containing a liquid anion-exchanger (General Mills Aliquat 336) in a solid support. Then molybdenum(VI), tungsten(VI) and vanadium(V) are selectively eluted with aqueous solutions containing dilute hydrogen peroxide and varying concentrations of sulphuric acid.

  2. Kinetic performance evaluation and perspectives of contemporary packed column capillary electrochromatography. (United States)

    De Smet, Seppe; Lynen, Frederic


    Capillary electrochromatography (CEC) is in essence a highly efficient and fast separation technique but practical constraints limit the current performance, robustness and routine implementation of the technique. In this work the kinetic performance limit (KPL) curve was used to evaluate commercial packed column CEC; this firstly in order to assess the broader applicability of the kinetic plot approach in electrodriven chromatographic techniques, and secondly to allow a more general unbiased comparison with HPLC performance. Evaluations were performed with a mixture of well retained and electrophoretically neutral phenones, to allow the observation of only chromatographic processes. Initial CEC retention time irreproducibility issues were solved by applying high acetonitrile content (80%) in the mobile phase, and solute retention was increased by increasing the phenone chain length. Comparison was performed with HPLC, with a column packed with an identical stationary phase to allow measurement of the performance under optimal conditions, and not with μ-LC on the CEC column as extra column peak broadening phenomena would thereby negatively affect the μ-LC performance. This comparison demonstrated that current HPLC performance largely outcompetes what is achievable with contemporary packed column CEC. Interestingly, significantly improved CEC performance could be obtained at lower temperatures (10°C) indicating a persistent degree of joule heating phenomena taking place in the contemporary packed column (100μm) CEC approach. Effective suppression of the latter opens possibilities for increasing the applicable voltage and outperforming HPLC and UHPLC.

  3. Evaluation of a column classification method using the separation of alfuzosin from its related substances. (United States)

    Szulfer, Jarosław; Plenis, Alina; Bączek, Tomasz


    The popularity and commercial availability of reversed-phase liquid chromatographic (RP-LC) stationary phases cause analysts to be often confronted with the problem of column selection. For this reason, general test methods to characterize RP-LC columns have been extensively studied since the 1970s. This paper focuses on correlating the column classification based on a method developed at the Katholieke Universiteit Leuven (KUL method) with the selectivity obtained for a real separation. The analysis of alfuzosin hydrochloride and related compounds was carried out according to the method prescribed in the European Pharmacopoeia (Ph. Eur.) monograph. This separation was performed on 36 new RP-LC stationary phases which had been previously characterized chromatographically. For deeper comparative analysis of KUL classification of the stationary RP-LC brands and their column performance in pharmaceutical practice two chemometric tools, such as principal component analysis (PCA) and cluster analysis (CA), have been used. It was shown that stationary phase classes closely related by KUL method gave comparable separation for alfuzosin and related compounds. Therefore, the column ranking system based on the evaluation of F-values can be considered as a helpful tool in the selection of a suitable column for pharmaceutical analyses.

  4. Fast HPLC for quality control of Harpagophytum procumbens by using a monolithic silica column: method transfer from conventional particle-based silica column. (United States)

    Schmidt, Alexander H


    The applicability of a monolithic C18-bonded silica column for the rapid HPLC separation of ingredients in medicinal plants and their phytopharmaceutical preparations has been evaluated in the author's laboratory. In this presentation, an existing method for the determination of the iridoid glycoside harpagoside in Harpagophytum procumbens (Devil's Claw) was successfully transferred from a conventional particle-based C18 silica column to a monolithic silica column. The very high porosity of the stationary phase allows chromatography with a much lower backpressure than on conventional columns. Therefore, the flow rate could be easily increased from 0.8 mL/min (particle-based column) to 5 mL/min (monolithic column) and the run-time reduced from 30 to 5 min (that is a reduction about 85% !), without losing any chromatographic resolution of the compound of interest. The amount of harpagoside was measured with the original method on a conventional particle-based silica column and on the adapted method on a monolithic silica column. The statistical mean t-test showed no significant differences of the variances and the means indicating that the fast HPLC method is an acceptable alternative. The shorter analysis time makes the method very valuable for commercial quality control of Harpagophytum extracts and its pharmaceutical preparations.

  5. Mechanism of simultaneously refolding and purification of proteins by hydrophobic interaction chromatographic unit and applications

    Institute of Scientific and Technical Information of China (English)

    GENG; Xindu(耿信笃); BAI; Quan(白泉)


    The hydrophobic amino acid residues of a denatured protein molecule tend to react with the particles of the stationary phase of hydrophobic interaction chromatography (STHIC). These hydrophobic interactions prevent the denatured protein molecules from aggregating with each other. The STHIC can provide high enough energy to a denatured protein molecule to make it dehydration and to refold it into its native or various intermediate states. The outcome not only depends on the specific interactions between amino acids, the structure of STHIC, but also depends on the association between the STHIC and mobile phase. The mechanism of protein refolding and the principle of its quality control by HPHIC were also presented. By appropriate selection of the chromatographic condition, several denatured proteins can be refolded and separated simultaneously in a single chromatographic run. A specially designed unit, with diameter much larger than its length, was designed and employed for both laboratory and preparative scales. That unit for the simultaneous renaturation and purification of proteins (USRPP) had the following four functions: to completely remove denaturant, to renature proteins, to separate renatured proteins from impurities, and to easily recycle waste denaturant. The efficiencies of refolding and purification of proteins by the USRPP are almost comparable to a usual long chromatographic column in laboratory. In preparative scale, USRPP can be easily, rapidly, and economically applied requiring a low pressure gradient. As an example, recombinant human interferon-? is employed to elucidate the application of the preparative USRPP.

  6. Solid-phase microextraction-gas chromatographic determination of volatile monoaromatic hydrocarbons in soil. (United States)

    Zygmunt, B; Namiesnik, J


    Benzene, toluene, ethylbenzene, three isomers of xylene, and cumene have been isolated and enriched from soil samples by a combination of water extraction at room and elevated temperature and headspace-solid-phase microextraction before their gas chromatographic-mass spectrometric (GC-MS) determination. The conditions used for all stages of sample preparation and chromatographic analysis were optimized. Analytes sampled on a polydimethylsiloxane-coated solid-phase microextraction fiber were thermally desorbed in the split/splitless injector of a gas chromatograph (GC) coupled with a mass spectrometer (MS). The desorption temperature was optimized. The GC separation was performed in a capillary column. Detection limits were found to be of the order of ca. 1 ng g(-1). Relative recoveries of the analytes from soils were found to be highly dependent on soil organic-matter content and on compound identity; they ranged from ca 92 to 96% for sandy soil (extraction at room temperature) and from ca 27 to 55% for peaty soil (extraction at elevated temperature). A few real-world soil samples were analyzed; the individual monoaromatic hydrocarbon content ranged from below detection limits to 6.4 ng g(-1) for benzene and 8.1 for the total of p- + m-xylene.

  7. A New Method for Determination of Adsorption and Desorption Coefficients of Pesticides with Soil Column Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)


    The adsorption and desorption coefficients of atrazine, methiocarb and simazine on a sandy loam soil were measured in this study with soil column liquid chromatographic (SCLC) technique. The adsorption and desorption data of all the three pesticides followed Freundlich isotherms revealing the existence of hysteresis. In comparing with other methods, SCLC method showed some characteristics such as rapidity, online and accuracy.

  8. Column: Every Last Byte

    Directory of Open Access Journals (Sweden)

    Simson Garfinkel


    Full Text Available Inheritance powder is the name that was given to poisons, especially arsenic, that were commonly used in the 17th and early 18th centuries to hasten the death of the elderly. For most of the 17th century, arsenic was deadly but undetectable, making it nearly impossible to prove that someone had been poisoned. The first arsenic test produced a gas—hardly something that a scientist could show to a judge. Faced with a growing epidemic of poisonings, doctors and chemists spent decades searching for something better.(see PDF for full column

  9. Detection and quantification of affinity ligand leaching and specific antibody fragment concentration within chromatographic fractions using surface plasmon resonance. (United States)

    Thillaivinayagalingam, Pranavan; Newcombe, Anthony R; O'Donovan, Kieran; Francis, Richard; Keshavarz-Moore, Eli


    Rapid analyses of chromatographic steps within a biopharmaceutical manufacturing process are often desirable to evaluate column performance, provide mass balance data and to permit accurate calculations of yields and recoveries. Using SPR (surface plasmon resonance) biosensor (Biacore) technology, we have developed a sandwich immunoassay to quantify polyclonal anti-digoxin Fab fragments used for the production of the FDA (Food and Drug Administration)-approved biotherapeutic DigiFab. The results show that specific Fab may be quantified in all affinity process streams and accurate yield and mass balance data calculated. Control experiments using sheep Fab and Fc indicate that the assay is specific to DigiFab. The quantification of potential leached ligand within chromatographic fractions may also be technically challenging, particularly when low-molecular-mass ligands are covalently coupled with an affinity absorbent. Typical methods to assess ligand leakage such as DDMA (digoxin-dicarboxymethoxylamine; digoxin analogue) often involve the use of labelled ligands and relatively complex and labour-intensive analytical techniques. Using the same analytical methodologies, an assay to detect leached or eluted ligand off the column was developed. The results indicate minimal levels of leached ligand in all chromatographic fractions, with total levels of leached DDMA calculated to be 1.52 microg. This is less than 0.01% of the total amount of DDMA coupled with the laboratory-scale affinity column. The SPR methods described in the present study may be applicable for the rapid in-process analysis of specific polyclonal Fab fragments (within a polyclonal mixture) and to rapidly assess leakage of small molecule ligands covalently attached to chromatographic supports.

  10. Multivariate analysis of chromatographic retention data as a supplementary means for grouping structurally related compounds. (United States)

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


    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.

  11. Chromatographic resolution of drug analogues: 3-hydroxy-3-methylglutarylcoenzyme A reductase inhibitors (statins). (United States)

    Tahir, Muhammad Saqlain; Adnan, Ahmad; Syed, Quratulain


    A high performance liquid chromatographic method for the simultaneous determination both qualitative and quantitative of cholesterol lowering statin drugs in pharmaceutical formulations has been developed. The most important advantage of developed method is that all seven statin drugs can be determined on a single chromatographic system without modification in detection wavelength. An organic modifier addition (25% v/v methanol) in the presence of buffer (20mM ammonium acetate; pH 4.0 adjusted with dilute acetic acid) played a key role in the resolution of statin drugs in gradient elution with acetonitrile. The drugs were separated on a Purospher Star 4.6mm × 25cm, 5μm, C18 column maintained at 25°C with 1mLmin(-1) flow rate using ultra violet detection at 240nm. Good separation (Rs > 2.5) was achieved in a short analysis allowing simultaneous determination of all seven statins. The effect of variation in flow rate, detection wavelength and column oven temperature was also studied. The proposed method was statistically validated in terms of precision, accuracy, linearity, specificity and robustness. The newly developed method proved to be specific, robust and accurate for the quantification of seven statins in commercial pharmaceutical formulations.

  12. High performance liquid chromatographic separation of eight drugs collected in Chinese Pharmacopoeia 2010 on amylose ramification chiral stationary phase

    Directory of Open Access Journals (Sweden)

    Yan Wang


    Full Text Available The enantiomers separation of eight pharmaceutical racemates collected in Chinese Pharmacopoeia 2010 (Ch.P2010, including nitrendipine, felodipine, omeprazole, praziquantel, sulpiride, clenbuterol hydrochloride, verapamil hydrochloride and chlorphenamine maleate, was performed on chiral stationary phase of amylose ramification by high performance liquid chromatography (HPLC on Chiralpak AD-H column and Chiralpak AS-H column with the mobile phase consisted of isopropanol and n-hexane. The detection wavelength and the flow rate were set at 254 nm and 0.7 mL/min, respectively. The effects of proportion of organic additives, alcohol displacer and temperature on the separation were investigated. The results indicated that eight chiral drugs were separated on chiral stationary phase of amylase ramification in normal phase chromatographic system. The chromatographic retention and resolution of enantiomers were adjusted by factors, including the changes of the concentration of alcohol displacer in mobile phase, organic alkaline modifier and column temperature. It was shown that the resolution was improved with reducing concentration of alcohol displacer. When the concentration of organic alkaline modifier was 0.2%, the resolution and the peak shape were fairly good. Most racemates mentioned above had the best resolution at column temperature of 25 °C. The best temperature should be kept unchanged in the process of separation so as to obtain stable separation results.

  13. Trigonal tricationic ionic liquids: a generation of gas chromatographic stationary phases. (United States)

    Payagala, Tharanga; Zhang, Ying; Wanigasekara, Eranda; Huang, Ke; Breitbach, Zachary S; Sharma, Pritesh S; Sidisky, Leonard M; Armstrong, Daniel W


    chromatographic method. The D core series had a high working temperature range, exceptional selectivities, and higher separation efficiencies than comparable polarity commercial columns. It appears that this specific type of multifunctional ILs may have the most promising future as a new generation of gas chromatographic stationary phases.


    Institute of Scientific and Technical Information of China (English)

    Tingyue Gu; Weiqing Zhou; Guanghui Ma; Zhiguo Su


    More and more biomolecules are being produced by the biotechnology industry for applications ranging from medicine and food to engineering materials. Liquid chromatography plays a center-stage role in a typical downstream process producing biomolecules such as recombinant proteins. Rigid gigaporous media are porous particles possessing large transecting through-pores with a pore-to-particle diameter ratio of dpore/dparticle> 0.01. They allow convective flow in the large through-pores, while the smaller diffusion-pores (typically several hundred angstroms in size) supply the needed surface areas. Because of the transecting gigapores, a portion of the mobile phase flows through the pores in addition to fluid flow in the interstitial spaces between the particles in a packed-bed column. This considerably lowers the operating column pressure drop. This lower pressure drop makes axial-direction scale-up of chromatographic columns possible to avoid pancake columns that invariably degrade separation resolution. The large gigapores also make the binding sites on the diffusion pore surfaces more accessible, thus increasing the loading capacity of large protein molecules that can be hindered sterically if only diffusion pores are present. This work discusses the development of rigid gigaporous media and their potential impact on the design of multi-stage downstream process from the angle of multi-scale analysis.

  15. High-performance liquid chromatographic assay of free norepinephrine, epinephrine, dopamine, vanillylmandelic acid and homovanillic acid. (United States)

    Gerlo, E; Malfait, R


    A procedure is described for the concurrent assay of free norepinephrine, epinephrine, dopamine, vanillylmandelic acid and homovanillic acid in physiological fluids using high-performance liquid chromatography with electrochemical detection. The column packing is an octadecyl-bonded silica. A single mobile phase containing 1-octanesulphonate is used for the assay of catecholamines and for the assay of the acidic metabolites. An efficient sample preparation scheme is presented for the isolation of the catecholamines and their acidic metabolites from the same sample aliquot. Catecholamines are extracted by ion exchange on small columns and adsorption on alumina, using dihydroxybenzylamine as an internal standard. Vanillylmandelic acid and homovanillic acid are recovered from the combined loading and washing effluents of the ion-exchange column by a solvent extraction procedure. Recovery of catecholamines averages 67%. The limit of detection for individual catecholamines is ca. 30 pg. Recoveries of vanillylmandelic acid and homovanillic acid average 77% and 87%, respectively. The use of the same mobile phase for the concurrent assay of catecholamines and their acidic metabolites considerably increases the throughput of samples in the chromatographic system by eliminating the time-consuming column-equilibration periods.

  16. Active flow management in preparative chromatographic separations: a preliminary investigation into enhanced separation using a curtain flow inlet fitting and segmented flow outlet fitting. (United States)

    Camenzuli, Michelle; Ritchie, Harald J; Ladine, James R; Shalliker, R Andrew


    Active flow management in the form of curtain flow sample introduction and segmented outlet flow control has been shown to enable sample to elute through a chromatography column under the principles of the "infinite diameter column". Such an elution process avoids the detrimental effects of the heterogeneity of particle-packed chromatographic columns by injecting the sample directly into the radial core region of the column, thus avoiding wall effects. The process described herein illustrates how the principles of the infinite diameter column can be applied using conventional injection devices suitable for long-term analysis that requires robust protocols. Using this approach, sensitivity in separation was 2.5 times greater than conventional chromatography, yielding a product at twice the concentration. Benefits of curtain flow injection are thus relevant to both preparative-scale and analytical-scale separations.

  17. Separation of rare earth by column chromatography using organic resins XAD/DEPHA

    Energy Technology Data Exchange (ETDEWEB)

    Zini, J.; Ferreira, J.C.; Bergamaschi, V.S.; Santos, I.; Carvalho, F.M.S., E-mail: [Instituto de Pesquisas Energeticas e Nucleares (CCCH/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Celulas a Combustivel e Hidrogenio


    The designation of light and heavy rare earth was used the fractionation used in separation processes. In this study the process of separation of rare earth, in groups, by chromatographic column consisting in fixing of cations these elements in an organic resin Amberlite XAD16 functionalized with the extracting agent DEPHA and another portion functionalized with a mixture of extractors DEPHA/TOP. The preparation of these resins was performed in two forms, one directly as the extracting agent to the resin and the other to be used in ethyl alcohol. Conditioned resins were introduced in chromatographic columns in separation of groups, light and heavy, using a standard solution of cerium nitrate and standard solution of holmium nitrate groups to represent light and heavy respectively. The characterization technique used to identify the rare earth elements was Spectrometry X-Ray Fluorescence (XRF). The results using the technique of chromatography were satisfactory, obtaining 100% separation of the elements. (author)

  18. Packed multi-channels for parallel chromatographic separations in microchips. (United States)

    Nagy, Andrea; Gaspar, Attila


    Here we report on a simple method to fabricate microfluidic chip incorporating multi-channel systems packed by conventional chromatographic particles without the use of frits. The retaining effectivities of different bottlenecks created in the channels were studied. For the parallel multi-channel chromatographic separations several channel patterns were designed. The obtained multipackings were applied for parallel separations of dyes. The implementation of several chromatographic separation units in microscopic size makes possible faster and high throughput separations.

  19. Thermodynamic and Extrathermodynamic Studies of Enantioseparation of Imidazolinone Herbicides on Chiralcel OJ Column


    Wenjian Lao


    A homologous series of chiral imidazolinone herbicide was previously resolved on Chiralcel OJ column in high performance liquid chromatography. However, the mechanism of the chiral separation remains unclear. In this study, chromatographic behaviors of five chiral imidazolinone herbicides were characterized by thermodynamic and extrathermodynamic methods in order to enhance the understanding of the chiral separation. Thermodynamic parameters of this study were derived from equilibrium constan...

  20. [Use of column and thin layer chromatography for detection of vanillyl mandelic acid in urine]. (United States)

    Riabichenko, V V; Barchukov, V G; Chernyĭ, A V; Salenko, Iu A


    The excretion of vanillylmandelic acid was measured by column chromatography of urinary samples on aluminum oxide with subsequent thin-layer chromatography on silica gel. Use of aluminum oxide allowed application of greater urine samples (up to 0.1% of 24-h diuresis) onto chromatographic plates and essentially improved the quality of separation of vanillylmandelic acid from other phenylcarbonic acids by thin-layer chromatography, as well as the specificity and reproducibility of measurements.

  1. European Analytical Column

    DEFF Research Database (Denmark)

    Karlberg, B.; Grasserbauer, M.; Andersen, Jens Enevold Thaulov


    The European Analytical Column has once more invited a guest columnist to give his views on various matters related to analytical chemistry in Europe. This year, we have invited Professor Manfred Grasserbauer of the Vienna University of Technology to present some of the current challenges...... for European analytical chemistry. During the period 2002–07, Professor Grasserbauer was Director of the Institute for Environment and Sustainability, Joint Research Centre of the European Commission (EC), Ispra, Italy. There is no doubt that many challenges exist at the present time for all of us representing...... a major branch of chemistry, namely analytical chemistry. The global financial crisis is affecting all branches of chemistry, but analytical chemistry, in particular, since our discipline by tradition has many close links to industry. We have already noticed decreased industrial commitment with respect...

  2. Column: File Cabinet Forensics

    Directory of Open Access Journals (Sweden)

    Simson Garfinkel


    Full Text Available Researchers can spend their time reverse engineering, performing reverse analysis, or making substantive contributions to digital forensics science. Although work in all of these areas is important, it is the scientific breakthroughs that are the most critical for addressing the challenges that we face.Reverse Engineering is the traditional bread-and-butter of digital forensics research. Companies like Microsoft and Apple deliver computational artifacts (operating systems, applications and phones to the commercial market. These artifacts are bought and used by billions. Some have evil intent, and (if society is lucky, the computers end up in the hands of law enforcement. Unfortunately the original vendors rarely provide digital forensics tools that make their systems amenable to analysis by law enforcement. Hence the need for reverse engineering.(see PDF for full column

  3. Why Hexagonal Basalt Columns? (United States)

    Hofmann, Martin; Anderssohn, Robert; Bahr, Hans-Achim; Weiß, Hans-Jürgen; Nellesen, Jens


    Basalt columns with their preferably hexagonal cross sections are a fascinating example of pattern formation by crack propagation. Junctions of three propagating crack faces rearrange such that the initial right angles between them tend to approach 120°, which enables the cracks to form a pattern of regular hexagons. To promote understanding of the path on which the ideal configuration can be reached, two periodically repeatable models are presented here involving linear elastic fracture mechanics and applying the principle of maximum energy release rate. They describe the evolution of the crack pattern as a transition from rectangular start configuration to the hexagonal pattern. This is done analytically and by means of three-dimensional finite element simulation. The latter technique reproduces the curved crack path involved in this transition.

  4. Micro-fabricated packed gas chromatography column based on laser etching technology. (United States)

    Sun, J H; Guan, F Y; Zhu, X F; Ning, Z W; Ma, T J; Liu, J H; Deng, T


    In this work, a micro packed gas chromatograph column integrated with a micro heater was fabricated by using laser etching technology (LET) for analyzing environmental gases. LET is a powerful tool to etch deep well-shaped channels on the glass wafer, and it is the most effective way to increase depth of channels. The fabricated packed GC column with a length of over 1.6m, to our best knowledge, which is the longest so far. In addition, the fabricated column with a rectangular cross section of 1.2mm (depth) × 0.6mm (width) has a large aspect ratio of 2:1. The results show that the fabricated packed column had a large sample capacity, achieved a separation efficiency of about 5800 plates/m and eluted highly symmetrical Gaussian peaks.

  5. Dependence of the efficiency of a multicapillary column on the liquid phase loading method. (United States)

    Zhdanov, V P; Sidelnikov, V N; Vlasov, A A


    One of the main approaches employed to reach fast chromatographic separation is based on using columns containing up to 1000 capillaries with the diameter size down to 10-100 microm. The efficiency of such columns depends on the dispersion of the capillary radius and on the way of the liquid-film loading. We present general equations describing these effects. Specifically, we show theoretically and experimentally that the separation efficiency can be improved by using the loading methods specially designed in order to take into account correlation between the film thickness and capillary radius.

  6. Enantioseparation of methamphetamine by supercritical fluid chromatography with cellulose-based packed column. (United States)

    Segawa, Hiroki; Iwata, Yuko T; Yamamuro, Tadashi; Kuwayama, Kenji; Tsujikawa, Kenji; Kanamori, Tatsuyuki; Inoue, Hiroyuki


    The enantiomers of methamphetamine were differentiated by supercritical fluid chromatography (SFC) with an enantioselective cellulose-based packed column. The optimization of the chromatographic conditions was achieved by changing column temperature, co-solvent proportion, additive concentration, flow rate and back pressure. In particular, the additive concentration crucially changed the resolution between the enantiomers. After determining the optimized conditions, the enantiomers of methamphetamine were successfully separated. The analytical precision, accuracy and limit of detection were checked by using the authentic standard and seized real samples. We believe that chiral SFC is a promising method for enantioseparation of forensic samples.


    Cooley, C.R.


    The patented extraction apparatus includes a column, perforated plates extending across the column, liquid pulse means connected to the column, and an imperforate spiral ribbon along the length of the column.

  8. Authentication of geographical origin of palm oil by chromatographic fingerprinting of triacylglycerols and partial least square-discriminant analysis. (United States)

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


    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%.

  9. Determination of trace inorganic anions in anionic surfactants by single-pump column-switching ion chromatography

    Institute of Scientific and Technical Information of China (English)

    Jia Jie Zhang; Hai Bao Zhu; Yan Zhu


    An ion chromatography method has been proposed for the determination of three common inorganic anions (chloride,nitrate and sulfate) in anionic surfactants using a single pump system.The new system consists of an ion exclusion column,a concentrator column,and an anion exchange column connected in series via two 6-ports valves in a Dionex ICS-2000 ion chromatograph.The valves were switched several times for removing surfactants,concentrating and separating the three anions.The chromatographic conditions were optimized.Detection limits (S/N =3) were in the range of 0.10-0.68 μg/L.The relative standard deviations (RSDs)of peak area were less than 4.6%.The recoveries were in the range of 84.1-112.6%.

  10. Determination of solute descriptors by chromatographic methods

    Energy Technology Data Exchange (ETDEWEB)

    Poole, Colin F., E-mail: [Department of Chemistry, Wayne State University, Detroit, MI 48202 (United States); Atapattu, Sanka N.; Poole, Salwa K.; Bell, Andrea K. [Department of Chemistry, Wayne State University, Detroit, MI 48202 (United States)


    The solvation parameter model is now well established as a useful tool for obtaining quantitative structure-property relationships for chemical, biomedical and environmental processes. The model correlates a free-energy related property of a system to six free-energy derived descriptors describing molecular properties. These molecular descriptors are defined as L (gas-liquid partition coefficient on hexadecane at 298 K), V (McGowan's characteristic volume), E (excess molar refraction), S (dipolarity/polarizability), A (hydrogen-bond acidity), and B (hydrogen-bond basicity). McGowan's characteristic volume is trivially calculated from structure and the excess molar refraction can be calculated for liquids from their refractive index and easily estimated for solids. The remaining four descriptors are derived by experiment using (largely) two-phase partitioning, chromatography, and solubility measurements. In this article, the use of gas chromatography, reversed-phase liquid chromatography, micellar electrokinetic chromatography, and two-phase partitioning for determining solute descriptors is described. A large database of experimental retention factors and partition coefficients is constructed after first applying selection tools to remove unreliable experimental values and an optimized collection of varied compounds with descriptor values suitable for calibrating chromatographic systems is presented. These optimized descriptors are demonstrated to be robust and more suitable than other groups of descriptors characterizing the separation properties of chromatographic systems.

  11. Quasi-adiabatic vacuum-based column housing for very high-pressure liquid chromatography. (United States)

    Gritti, Fabrice; Gilar, Martin; Jarrell, Joseph A


    A prototype vacuum-based (10(-6)Torr) column housing was built to thermally isolate the chromatographic column from the external air environment. The heat transfer mechanism is solely controlled by surface radiation, which was minimized by wrapping the column with low-emissivity aluminum tape. The adiabaticity of the column housing was quantitatively assessed from the measurement of the operational pressure and fluid temperature at the outlet of a 2.1mm×100mm column (sub-2 μm particles). The pressure drop along the column was raised up to 1kbar. The enthalpy balance of the eluent (water, acetonitrile, and one water/acetonitrile mixture, 70/30, v/v) showed that less than 1% of the viscous heat generated by friction of the fluid against the packed bed was lost to the external air environment. Such a vacuum-based column oven minimizes the amplitude of the radial temperature gradients across the column diameter and maximizes its resolving power.

  12. Sum of ranking differences to rank stationary phases used in packed column supercritical fluid chromatography. (United States)

    West, Caroline; Khalikova, Maria A; Lesellier, Eric; Héberger, Károly


    The identification of a suitable stationary phase in supercritical fluid chromatography (SFC) is a major source of difficulty for those with little experience in this technique. Several protocols have been suggested for column classification in high-performance liquid chromatography (HPLC), gas chromatography (GC), and SFC. However, none of the proposed classification schemes received general acceptance. A fair way to compare columns was proposed with the sum of ranking differences (SRD). In this project, we used the retention data obtained for 86 test compounds with varied polarity and structure, analyzed on 71 different stationary phases encompassing the full range in polarity of commercial packed columns currently available to the SFC chromatographer, with a single set of mobile phase and operating conditions (carbon dioxide-methanol mobile phase, 25°C, 150bar outlet pressure, 3ml/min). First, a reference column was selected and the 70 remaining columns were ranked based on this reference column and the retention data obtained on the 86 analytes. As these analytes previously served for the calculation of linear solvation energy relationships (LSER) on the 71 columns, SRD ranks were compared to LSER methodology. Finally, an external comparison based on the analysis of 10 other analytes (UV filters) related the observed selectivity to SRD ranking. Comparison of elution orders of the UV filters to the SRD rankings is highly supportive of the adequacy of SRD methodology to select similar and dissimilar columns.

  13. Analysis of global components in Ganoderma using liquid chromatography system with multiple columns and detectors. (United States)

    Qian, Zhengming; Zhao, Jing; Li, Deqiang; Hu, Dejun; Li, Shaoping


    In present study, a multiple columns and detectors liquid chromatography system for analysis of global components in traditional Chinese medicines was developed. The liquid chromatography system was consist of three columns, including size exclusion chromatography column, hydrophilic interaction chromatography column, and reversed phase chromatography column, and three detectors, such as diode array detector, evaporative light scattering detector, and mass spectrometry detector, based on column switching technique. The developed multiple columns and detectors liquid chromatography system was successfully applied to the analysis of global components, including macromolecular (polysaccharides), high (nucleosides and sugars)-, and low (triterpenes)-polarity small molecular compounds in Ganoderma, a well-known Chinese medicinal mushroom. As a result, one macromolecular chromatographic peak was found in two Ganoderma species, 19 components were identified in Ganoderma lucidum (two sugars, three nucleosides, and 14 triterpenes), and four components (two sugars and two nucleosides) were identified in Ganoderma sinense. The developed multiple columns and detectors liquid chromatography system was helpful to understand comprehensive chemical characters in TCMs.

  14. Compact electron beam focusing column

    Energy Technology Data Exchange (ETDEWEB)

    Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani


    A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2-D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

  15. Micellar liquid chromatographic determination of arbutin and hydroquinone in medicinal plant extracts and commercial cosmetic products. (United States)

    Thogchai, W; Liawruangrath, B


    A simple micellar liquid chromatographic (MLC) procedure for simultaneous determination of arbutin and hydroquinone in medicinal plant extracts and commercial cosmetic products was proposed. This method was developed and validated. The chromatographic conditions were also optimized. All analyses were performed at room temperature in an isocratic mode, using a mixture of 1% (v/v) acetonitrile and 0.006 mol L⁻¹ Brij 35 (pH 6.0) as a mobile phase. The flow rate was set at 1.0 mL min⁻¹. The analytical column was a 150 × 3.9 mm Nova-Pak C-18 column. The effluent from the analytical column was monitored by UV detection at 280 nm. Under the optimum conditions, arbutin and hydroquinone could be determined within a concentration range of 2-50 μg mL⁻¹ of arbutin, and hydroquinone was obtained with the regression equations; y = 0.045x + 0.042 (r² = 0.9923) and y = 0.091x + 0.050 (r² = 0.9930) respectively. The limits of detection were found to be 0.51 μg mL⁻¹ and 0.37 μg mL⁻¹ for arbutin and hydroquinone respectively. The proposed MLC method was applied for the determination of arbutin and hydroquinone contents in medicinal plant extracts and commercial cosmetic products. This proposed MLC method is thus suitable for routine analysis of arbutin and hydroquinone in the pharmaceutical formulations, cosmetic products and raw medicinal plant extracts.

  16. Development of immobilized membrane-based affinity columns for use in the online characterization of membrane bound proteins and for targeted affinity isolations

    Energy Technology Data Exchange (ETDEWEB)

    Moaddel, Ruin [Gerontology Research Center, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825 (United States); Wainer, Irving W. [Gerontology Research Center, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825 (United States)]. E-mail:


    Membranes obtained from cell lines that express or do not express a target membrane bound protein have been immobilized on a silica-based liquid chromatographic support or on the surface of an activated glass capillary. The resulting chromatographic columns have been placed in liquid chromatographic systems and used to characterize the target proteins and to identify small molecules that bind to the target. Membranes containing ligand gated ion channels, G-protein coupled receptors and drug transporters have been prepared and characterized. If a marker ligand has been identified for the target protein, frontal or zonal displacement chromatographic techniques can be used to determine binding affinities (K {sub d} values) and non-linear chromatography can be used to assess the association (k {sub on}) and dissociation (k {sub off}) rate constants and the thermodynamics of the binding process. Membrane-based affinity columns have been created using membranes from a cell line that does not express the target protein (control) and the same cell line that expresses the target protein (experimental) after genomic transfection. The resulting columns can be placed in a parallel chromatography system and the differential retention between the control and experimental columns can be used to identify small molecules and protein that bind to the target protein. These applications will be illustrated using columns created using cellular membranes containing nicotinic acetylcholine receptors and the drug transporter P-glycoprotein.

  17. Prediction of Peak Shape and Characterization of Column Performance in Liquid Chromatography as a Function of Flow Rate

    Directory of Open Access Journals (Sweden)

    Juan José Baeza-Baeza


    Full Text Available Traditionally, column performance in liquid chromatography has been studied using information from the elution of probe compounds at different flow rates through van Deemter plots, which relate the column plate height to the linear mobile phase velocity. A more recent approach to characterize columns is the representation of the peak widths (or the right and left peak half-widths for a set of compounds versus their retention times, which, for isocratic elution, give rise to almost linear plots. In previous work, these plots have been shown to facilitate the prediction of peak profiles (width and asymmetry with optimization purposes. In this work, a detailed study on the dependence of the peak widths (or half-widths on the flow rate is reported. A new approach to quantify the deterioration of column performance for slow and fast flow rates and to characterize chromatographic columns is proposed. The approach makes use of the width (or half-widths for a set of compounds with similar interaction kinetics and does not require knowledge of the extra-column contributions to the total variance. The chromatographic data of two sets of compounds of different natures (sulfonamides and β-blockers, eluted from Spherisorb and Chromolith columns with acetonitrile-water mixtures, are used to illustrate the approach.

  18. Gas chromatographic determination of yohimbine in commercial yohimbe products. (United States)

    Betz, J M; White, K D; der Marderosian, A H


    The bark of Pausinystalia yohimbe [K. Schumann] Pierre (Rubiaceae), long valued as an aphrodisiac in West Africa, recently has been promoted in the United States as a dietary supplement alternative to anabolic steroids for enhancement of athletic performance. As the number of yohimbe products on the retail market increases, concerns about their safety are raised because of the reported toxicity of yohimbine (the major alkaloid of the plant). Although plant materials are usually identified microscopically, we were unable to identify them in many of the products, because as their labels indicated, the products were mixtures of various botanicals or were bark extracts and contained little or no plant material. A method for extraction and capillary gas chromatographic (GC) separation of the alkaloids of P. yohimbe was, therefore, developed and used to analyze a number of commercial yohimbe products. The method involved solvent extraction and partitioning in chloroform-water followed by separation on a methyl silicone capillary GC column (N-P detection). Comparisons of chromatograms of extracts of authentic bark with those of commercial products indicated that, although many products contained measurable quantities of the alkaloid yohimbine, they were largely devoid of the other alkaloids previously reported in this species. Concentrations of yohimbine in the commercial products ranged from < 0.1 to 489 ppm, compared with 7089 ppm in the authentic material. Authentic bark has been reported to contain up to 6% total alkaloids, 10-15% of which are yohimbine. The possible presence of undeclared diluents in the products was indicated by peaks in product chromatograms but not in those of authentic bark.

  19. Quantitative analysis combined with chromatographic fingerprint for comprehensive evaluation of Xiaoer Chaigui Tuire granules by HPLC-DAD. (United States)

    Liu, Hong-Ming; Nie, Lei


    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.

  20. HPLC method development for the online-coupling of chromatographic Perilla frutescens extract separation with xanthine oxidase enzymatic assay. (United States)

    Kaufmann, Christine M; Grassmann, Johanna; Letzel, Thomas


    Enzyme-regulatory effects of compounds contained in complex mixtures can be unveiled by coupling a continuous-flow enzyme assay to a chromatographic separation. A temperature-elevated separation was developed and the performance was tested using Perilla frutescens plant extracts of various polarity (water, methanol, ethanol/water). Owning to the need of maintaining sufficient enzymatic activity, only low organic solvent concentrations can be added to the mobile phase. Hence, to broaden the spectrum of eluting compounds, two different organic solvents and various contents were tested. The chromatographic performance and elution was further improved by the application of a moderate temperature gradient to the column. By taking the effect of eluent composition as well as calculated logD values and molecular structure of known extract compounds into account, unknown features were tentatively assigned. The method used allowed the successful observation of an enzymatic inhibition caused by P. frutescens extract.

  1. Probabilistic peak detection for first-order chromatographic data

    NARCIS (Netherlands)

    Lopatka, M.; Vivó-Truyols, G.; Sjerps, M.J.


    We present a novel algorithm for probabilistic peak detection in first-order chromatographic data. Unlike conventional methods that deliver a binary answer pertaining to the expected presence or absence of a chromatographic peak, our method calculates the probability of a point being affected by suc

  2. Practical design of stepped columns

    NARCIS (Netherlands)

    Girao Coelho, A.M.; Simao, P.D.; Bijlaard, F.S.K.


    This paper deals with buckling aspects of the design of stepped columns in heavy mill buildings. In these structures, columns have to carry significant axial loads that usually act eccentrically and strength reducing bending moments due to lateral loads. A simple physical model for buckling behaviou

  3. An Undergraduate Column Chromatography Experiment. (United States)

    Danot, M.; And Others


    Background information, list of materials needed, and procedures used are provided for an experiment designed to introduce undergraduate students to the theoretical and technical aspects of column chromatography. The experiment can also be shortened to serve as a demonstration of the column chromatography technique. (JN)

  4. Simple gas chromatographic method for furfural analysis. (United States)

    Gaspar, Elvira M S M; Lopes, João F


    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.

  5. A Robust and Fully-Automated Chromatographic Method for the Quantitative Purification of Ca and Sr for Isotopic Analysis (United States)

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


    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.

  6. 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)



    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.

  7. Mush Column Magma Chambers (United States)

    Marsh, B. D.


    Magma chambers are a necessary concept in understanding the chemical and physical evolution of magma. The concept may well be similar to a transfer function in circuit or time series analysis. It does what needs to be done to transform source magma into eruptible magma. In gravity and geodetic interpretations the causative body is (usually of necessity) geometrically simple and of limited vertical extent; it is clearly difficult to `see' through the uppermost manifestation of the concentrated magma. The presence of plutons in the upper crust has reinforced the view that magma chambers are large pots of magma, but as in the physical representation of a transfer function, actual magma chambers are clearly distinct from virtual magma chambers. Two key features to understanding magmatic systems are that they are vertically integrated over large distances (e.g., 30-100 km), and that all local magmatic processes are controlled by solidification fronts. Heat transfer considerations show that any viable volcanic system must be supported by a vertically extensive plumbing system. Field and geophysical studies point to a common theme of an interconnected stack of sill-like structures extending to great depth. This is a magmatic Mush Column. The large-scale (10s of km) structure resembles the vertical structure inferred at large volcanic centers like Hawaii (e.g., Ryan et al.), and the fine scale (10s to 100s of m) structure is exemplified by ophiolites and deeply eroded sill complexes like the Ferrar dolerites of the McMurdo Dry Valleys, Antarctica. The local length scales of the sill reservoirs and interconnecting conduits produce a rich spectrum of crystallization environments with distinct solidification time scales. Extensive horizontal and vertical mushy walls provide conditions conducive to specific processes of differentiation from solidification front instability to sidewall porous flow and wall rock slumping. The size, strength, and time series of eruptive behavior

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

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


    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.

  9. A validated stability-indicating liquid chromatographic method for determination of process related impurities and degradation behavior of Irbesartan in solid oral dosage


    Nishant Goswami


    The present work describes the development and validation of a stability-indicating RP-HPLC method for the estimation of degradation and process related impurities of Irbesartan, namely Impurity-1, Impurity-2, Impurity-3 and Impurity-4. The developed LC method was validated with respect to specificity, limit of detection and quantification, linearity, precision, accuracy and robustness. The chromatographic separation was achieved on Hypersil Octadecylsilyl (4.6 mm × 150 mm, 3 μm) column by us...

  10. Development of liquid chromatographic method for simultaneous determination of mycophenolate mofetil and its degradation product mycophenolic acid in dosage form. (United States)

    Protić, A; Zivanović, Lj; Zecević, M; Jocić, B


    In this paper, a chemometrical approach is applied for the development of a reversed-phase high-performance liquid chromatography method for the simultaneous determination of mycophenolate mofetil and its degradation product mycophenolic acid in dosage form. The fractional factorial design is used in screening experiments for selecting the variables that significantly influence the chromatographic procedure. The investigated variables are column type, temperature of the column, and composition of the mobile phase (with respect to pH and the percentage of organic modifier). Investigation is performed using two columns, XTerra (RP 18, 150 mmx3.9 mm) and Chromolith (RP-18e, 100 mmx4.6 mm). Because the column type shows no influence on separation process, the Chromolith column is further used due to its ability to achieve a high-speed separation without loss of column efficiency. Total analysis time is reduced from 8.34 min on XTerra to 1.27 min on Chromolith. The columns' efficiency, analysis cost, and peak symmetries are briefly compared. For both substances, only two variables are found significant: percentage of acetonitrile and pH of the water phase. Afterward, the main variables are optimized using response surface methodology for visualization and easier identification of optimal conditions. The optimal conditions are obtained with mobile phase composition of acetonitrile-15 mM phosphate buffer (pH adjusted to 4.0 with 85% orthophosphoric acid) (35:65, v/v) at the flow rate of 5 mL/min. The temperature of the column is adjusted to 25 degrees C and detection is performed at 254 nm.

  11. Relating pressure tuned coupled column ensembles with the solvation parameter model for tunable selectivity in gas chromatography. (United States)

    Sharif, Khan M; Kulsing, Chadin; Chin, Sung-Tong; Marriott, Philip J


    The differential pressure drop of carrier gas by tuning the junction point pressure of a coupled column gas chromatographic system leads to a unique selectivity of the overall separation, which can be tested using a mixture of compounds with a wide range of polarity. This study demonstrates a pressure tuning (PT) GC system employing a microfluidic Deans switch located at the mid-point of the two capillary columns. This PT system allowed variations of inlet-outlet pressure differences of the two columns in a range of 52-17psi for the upstream column and 31-11psi for the downstream column. Peak shifting (differential migration) of compounds due to PT difference are related to a first order regression equation in a Plackett-Burman factorial study. Increased first (upstream) column pressure drop makes the second column characteristics more significant in the coupled column retention behavior, and conversely increased second (downstream) column pressure drop makes the first column characteristics more apparent; such variation can result in component swapping between polar and non-polar compounds. The coupled column system selectivity was evaluated in terms of linear solvation energy relationship (LSER) parameters, and their relation with different pressure drop effects has been constructed by applying multivariate principle component analysis (PCA). It has been found that the coupled column PT system descriptors provide a result that shows a clear clustering of different pressure settings, somewhat intermediate between those of the two commercial columns. This is equivalent to that obtained from a conventional single-column GC analysis where the interaction energy contributed from the stationary phases can be significantly adjusted by choice of midpoint PT. This result provides a foundation for pressure differentiation for selectivity enhancement.

  12. Chromatographic analysis of olopatadine in hydrophilic interaction liquid chromatography. (United States)

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


    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.

  13. [Rapid determination of propranolol enantiomers in rat plasma by column-switching-high performance liquid chromatography]. (United States)

    Wu, Xiaoyu; Wang, Rong; Xie, Hua; Wang, Jianfeng; Jia, Zhengping; Zhang, Qiang; Wang, Xianhua


    A high performance liquid chromatographic (HPLC) method with column-switching was developed and validated for rapid determination of two propranolol enantiomers in rat plasma. The column of restricted-access media was used as a pre-treatment column and a Chiralcel OD-RH was used as analytical column. The plasma samples were injected directly into the pretreatment column to remove plasma protein and endogenous constituents as well as to retent the propranolol enantiomers in the column using the mobile phase of borate buffer (pH 8.5)-methanol (95:5, v/v) at the flow rate of 1.0 mL/min. Then the propranolol enantiomers were transferred to the Chiralcel OD-RH column using the mobile phase of isopropanol-ethanol-0.2 mmol/L borate buffer (pH 8.5) (30: 30: 40, v/v/v) at a flow rate of 0.8 mL/min by column-switching technology. The column-switching time was 3.0 min, the used wavelength was 293 nm and the column temperature was set at 25 degrees C. The calibration curve showed excellent linear relationship (r = 0.999 5) in the concentration range from 25 mg/L to 500 mg/L for propranolol enantiomers in plasma. The intra-day and inter-day assay precisions and accuracies were well and the relative standard deviations (RSDs) were less than 5%. The average recoveries (n = 6) of the two enantiomers at 3 spiked levels were from 97.89% to 101.56%. All the values of the method validation were within the generally accepted criteria for biological sample analysis. The results show that the method is convenient, quick, sensitive and accurate. The method was successfully applied in the determination of propranolol enantiomers in rat blood pharmacokinetics study.

  14. Sol-gel multicapillary columns for gas-solid chromatography. (United States)

    Sidelnikov, Vladimir N; Patrushev, Yuri V; Belov, Yuri P


    In this work, we report the method for the preparation of multicapillary columns (MCCs) for gas-solid chromatography. The porous layer adsorbent is formed on capillary walls by the hydrolysis of aluminum alkoxide in the presence of polypropylene glycol (PPG) and HCl. Porosity and selectivity of the adsorbent depend on reaction conditions and the concentration of PPG. Sol-gel MCCs are well suited for high-speed chromatographic analysis of light hydrocarbons by gas-solid chromatography. Nine-component mixtures of C1-C4 hydrocarbons are separated within 8-12 s. The efficiency of 25-30 cm long alumina sol-gel MCCs consisting of approximately 1400 capillaries of 40 microm diameter is up to 2500-3000 theoretical plates.

  15. Direct probing of chromatography columns by laser-induced fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    McGuffin, V.L.


    This report summarizes the progress and accomplishments of this research project from September 1, 1989 to February 28, 1993. During this period, we have accomplished all of the primary scientific objectives of the research proposal: (1) constructed and evaluated a laser-induced fluorescence detection system that allows direct examination of the chromatographic column, (2) examined nonequilibrium processes that occur upon solute injection and elution, (3) examined solute retention in liquid chromatography as a function of temperature and pressure, (4) examined solute zone dispersion in liquid chromatography as a function of temperature and pressure, and (5) developed appropriate theoretical models to describe these phenomena. In each of these studies, substantial knowledge has been gained of the fundamental processes that are responsible for chromatographic separations. In addition to these primary research objectives, we have made significant progress in three related areas: (1) examined pyrene as a fluorescent polarity probe insupercritical fluids and liquids as a function of temperature and pressure, (2) developed methods for the class-selective identification of polynuclear aromatic hydrocarbons in coal-derived fluids by microcolumn liquid chromatography with fluorescence quenching detection, and (3) developed methods for the determination of saturated and unsaturated (including omega-3) fatty acids in fish oil extracts by microcolumn liquid chromatography with laser-induced fluorescence detection. In these studies, the advanced separation and detection techniques developed in our laboratory are applied to practical problems of environmental and biomedical significance.

  16. Water Column Sonar Data Collection (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The collection and analysis of water column sonar data is a relatively new avenue of research into the marine environment. Primary uses include assessing biological...

  17. Development of a chromatographic method for the determination of saquinavir in plasma samples of HIV patients. (United States)

    Campanero, M A; Escolar, M; Arangoa, M A; Sádaba, B; Azanza, J R


    A simple, sensitive and reproducible high-performance liquid chromatographic method for detecting and quantifying saquinavir in human plasma is described. Verapamil was used as internal standard. The method employes a single liquid-liquid extraction step with tert-butil methyl ether followed by chromatography on a Lichrospher 60 Select B C8 reversed-phase column. Ultraviolet detection was used to identify the compounds of interest. The quantitation limit of saquinavir was 1 ng/mL and only 0.5 mL of plasma sample was required for the determination. The average saquinavir recoveries over a concentration range of 2.5-500 ng/mL ranged from 86 to 95%. Precision and accuracy did not exceed 5%.

  18. Rocket-powered high-performance liquid chromatographic analysis of plant ascorbate and glutathione. (United States)

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


    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.

  19. A fast and accurate numerical method for solving simulated moving bed (SMB) chromatographic separation problems

    DEFF Research Database (Denmark)

    Lim, Young-il; Jørgensen, Sten Bay


    Solving simulated moving bed (SMB) chromatography models requires fast and accurate numerical techniques, since their system size computed is large due to multi-columns and multi-components, in addition the axial solution profiles contain steep moving fronts. The space-time conservation element...... chromatographic problems, non-dissipative and accurate solutions are obtained and fast calculation is achieved in this study. The effects of two-computational parameters (CFL number and mesh stepsize) on the numerical solution are examined, illustrating two SMB processes whose Peclet and Stanton numbers...... and larger mesh stepsize is permitted. In the case study of the SMB adsorption problems, a large CFL number and sufficient number of mesh points (or small mesh stepsize) are desirable to reduce the calculation time and increase accuracy. (C) 2004 Elsevier Ltd. All rights reserved....

  20. The Purification of Natural and Recombinant Peptide Antibodies by Affinity Chromatographic Strategies. (United States)

    Ma, Hui; O'Kennedy, Richard


    The purification of peptide antibodies (e.g., IgG, IgY, scFv, and Fab) are described in this chapter. Affinity chromatographic purification, a very convenient and effective antibody purification strategy, is used to isolate peptide antibodies based on specific binding, i.e., binding of the antibody to a column on which its specific ligand is immobilized with subsequent elution of the purified antibody. In addition, the application of purification methods based on the use of proteins A, G, and L, each of which bind to specific domains on an antibody/fragment, or the use of specific tags (e.g., histidine and biotin) attached to antibodies or antigens are also described.

  1. Solid-phase extraction and liquid chromatographic quantitation of quinfamide in biological samples. (United States)

    Morales, J M; Jung, C H; Alarcón, A; Barreda, A


    This paper describes a high-performance liquid chromatographic method for the assay of quinfamide and its main metabolite, 1-(dichloroacetyl)-1,2,3,4,-tetrahydro-6-quinolinol, in plasma, urine and feces. It requires 1 ml of biological fluid, an extraction using Sep-Pack cartridges and acetonitrile for drug elution. Analysis was performed on a CN column (5 microm) using water-acetonitrile-methanol (40:50:10) as a mobile phase at 269 nm. Results showed that the assay was linear in the range between 0.08 and 2.0 microg/ml. The limit of quantitation was 0.08 microg/ml. Maximum assay coefficient of variation was 14%. Recovery obtained in plasma, urine and feces ranged from 82% to 98%.

  2. 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.

  3. Liquid chromatographic determination and depletion profile of oxytetracycline in milk after repeated intramuscular administration in sheep. (United States)

    Fletouris, Dimitrios J; Papapanagiotou, Elias P; Nakos, Dimitrios S


    A simple, rapid and specific ion-pair liquid chromatographic method for the routine determination of the marker residue of oxytetracycline in sheep milk, at levels as low as 20 microg/kg, has been developed. Milk samples were acidified and extracted with acetonitrile. The extracts were purified by treatment with ammonium sulphate and concentrated into diluted phosphoric acid. Separation was carried out isocratically on a Nucleosil C(18) column using a mobile phase that contained both positively and negatively charged pairing ions. The in-house validated method gave overall recoveries and overall relative standard deviations better than 86% and 4.6%, respectively. The method was successfully applied to study the depletion of oxytetracycline in sheep milk and to estimate the withdrawal period after intramuscular administration of a commercial oxytetracycline formulation.

  4. Chromatographic Monoliths for High-Throughput Immunoaffinity Isolation of Transferrin from Human Plasma

    Directory of Open Access Journals (Sweden)

    Irena Trbojević-Akmačić


    Full Text Available Changes in protein glycosylation are related to different diseases and have a potential as diagnostic and prognostic disease biomarkers. Transferrin (Tf glycosylation changes are common marker for congenital disorders of glycosylation. However, biological interindividual variability of Tf N-glycosylation and genes involved in glycosylation regulation are not known. Therefore, high-throughput Tf isolation method and large scale glycosylation studies are needed in order to address these questions. Due to their unique chromatographic properties, the use of chromatographic monoliths enables very fast analysis cycle, thus significantly increasing sample preparation throughput. Here, we are describing characterization of novel immunoaffinity-based monolithic columns in a 96-well plate format for specific high-throughput purification of human Tf from blood plasma. We optimized the isolation and glycan preparation procedure for subsequent ultra performance liquid chromatography (UPLC analysis of Tf N-glycosylation and managed to increase the sensitivity for approximately three times compared to initial experimental conditions, with very good reproducibility. This work is licensed under a Creative Commons Attribution 4.0 International License.

  5. Gas-liquid chromatographic determination of adipate content of acetylated di-starch adipate. (United States)

    Mitchell, G A; Vanderbist, M J; Meert, F F


    A gas-liquid chromatographic method is described for rapid, quantitative determination of adipate content of acetylated di-starch adipate. The adipate group is very labile and, under mild alkaline conditions at ambient temperature, is easily hydrolyzed from the starch. Free adipic acid is formed by acidification of the solution with HCl, and then extracted with ethyl acetate. Ethyl acetate is removed under vacuum distillation, and a silyl derivative of the adipic acid is formed. Glutaric acid internal standard is introduced into the original starch sample before hydrolysis. An aliquot of the silylated solution is injected into a gas chromatograph fitted with a column having silicone oil as the active phase. A flame ionization detector is also incorporated. Results correlate well the amount of adipylating reagent used. No adipic acid is detectable when a hydrolyzed, extracted sample of acetylated di-starch adipate is subjected to a second extraction. Recovery levels of adipic acid, from starches fortified with 100-500 ppm, are in the range of 97-102.5%.

  6. Development and validation of a specific stability indicating high performance liquid chromatographic method for rizatriptan benzoate. (United States)

    Mallikarjuna Rao, B; Sangaraju, Sivaiah; Srinivasu, M K; Madhavan, P; Lalitha Devi, M; Rajendra Kumar, P; Chandrasekhar, K B; Arpitha, Ch; Satya Balaji, T


    A gradient, reversed-phase liquid chromatographic (RP-LC) method was developed for the quantitative determination of rizatriptan benzoate, used to treat relieves migraine headache symptoms. The developed method can be also employed for the related substance determination in bulk samples. Forced degradation studies were performed on bulk sample of rizatriptan benzoate using acid (0.5 N hydrochloric acid), base (0.1 N sodium hydroxide), oxidation (3.0% hydrogen peroxide), water hydrolysis, heat (60 degrees C) and photolytic degradation. Mild degradation of the drug substance was observed in base hydrolysis and considerable degradation observed during oxidative stress. The chromatographic method was fine tuned using the samples generated from forced degradation studies. Good resolution between the peaks corresponds to degradation products and the analyte was achieved on Agilent Zorbax SB-CN (250 mm x 4.6 mm, 5 microm) column. The mobile phase consists of a mixture of aqueous potassium di hydrogen ortho phosphate (pH 3.4), acetonitrile and methanol. The stress sample solutions were assayed against the qualified reference standard of rizatriptan benzoate and the mass balance in each case was close to 99.7% indicating that the developed method is stability indicating. Validation of the developed method was carried out as per ICH requirements.


    Directory of Open Access Journals (Sweden)

    Sheikh Rahila


    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.

  8. Liquid chromatographic and spectrophotometric methods for the determination of erythromycin stearate and trimethoprim in tablets

    Directory of Open Access Journals (Sweden)

    Sonia T. Hassib


    Full Text Available Simple, accurate and precise reversed-phase liquid chromatographic (LC and spectrophotometric methods have been developed and validated for the determination of erythromycin stearate (ERS and trimethoprim (TMP in mixture. In LC method, chromatographic separation was achieved on a Symmetry® Waters C18 column (150 × 4.6 mm, 5 μm based on isocratic elution using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (9:acetonitrile:water (25:100:50, v/v/v at a flow rate of 1.6 ml min−1 with UV detection at 210 nm for ERS and 280 nm for TMP. Besides, two spectrophotometric methods were applied after reaction with perchloric acid (12 M which gives a colored product with ERS. Then, the spectral interference between the colored product of ERS and TMP was resolved by either ratio spectra derivative spectrophotometry in the first spectrophotometric method or chemometric techniques, namely classical least-squares (CLS, principal component regression (PCR and partial least-squares regression (PLS in the second spectrophotometric method. The results were statistically compared using one-way analysis of variance (ANOVA. The methods developed were satisfactorily applied to the analysis of the pharmaceutical preparation containing the two drugs and proved to be specific and accurate for the quality control of the cited drugs in pharmaceutical dosage forms.

  9. Development and Validation of Reversed-Phase High Performance Liquid Chromatographic Method for Hydroxychloroquine Sulphate. (United States)

    Singh, A; Roopkishora; Singh, C L; Gupta, R; Kumar, S; Kumar, M


    In the present work new, simple reversed-phase high performance liquid chromatographic method was developed and validated for the determination of hydroxychloroquine sulphate in blood plasma. Chloroquine sulphate was used as an internal standard. The chromatographic separation was achieved with octadecyl silane Hypersil C18 column (250×6 mm, 5 μm) using water and organic (acetonitrile:methanol: 50:50, v/v) mobile phase in 75:25 v/v ratio, with sodium 1-pentanesulfonate and phosphoric acid. This organic phase was maintained at pH 3.0 by orthophosphoric acid. The flow rate of 2.0 ml/min(.) with detection at 343 nm was used in the analysis. The calibration curve of standard hydroxychloroquine sulphate was linear in range 0.1-20.0 μg/ml. The method was validated with respected to linearity, range, precision, accuracy, specificity and robustness studies according to ICH guidelines. The method was found to be accurate and robust to analyze the hydroxychloroquine sulphate in plasma samples.

  10. Development and validation of a reversed phase liquid chromatographic method for analysis of griseofulvin and impurities. (United States)

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


    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.

  11. Development and validation of a high-performance liquid chromatographic method for bioanalytical application with rimonabant. (United States)

    Bhaumik, Uttam; Ghosh, Animesh; Chatterjee, Bappaditya; Sengupta, Pinaki; Darbar, Soumendra; Roy, Bikash; Nandi, Utpal; Pal, Tapan K


    A simple and feasible high-performance liquid chromatographic method with UV detection was developed and validated for the quantification of rimonabant in human plasma. The chromatographic separation was carried out in a Hypersil BDS, C(18) column (250 mm x 4.6mm; 5 microm). The mobile phase was a mixture of 10 mM phosphate buffer and acetonitrile (30:70, v/v) at a flow rate of 1.0 ml/min. The UV detection was set at 220 nm. The extraction recovery of rimonabant in plasma at three quality control (QC) samples was ranged from 84.17% to 92.64%. The calibration curve was linear for the concentration range of 20-400 ng/ml with the correlation coefficient (r(2)) above 0.9921. The method was specific and sensitive with the limit of quantification of 20 ng/ml. The accuracy and precision values obtained from six different sets of QC samples analyzed in separate occasions ranged from 88.13% to 106.48% and 0.13% to 3.61%, respectively. In stability tests, rimonabant in human plasma was stable during storage and assay procedure. The method is very simple, sensitive and economical and the assay was applied to human plasma samples in a clinical (pharmacokinetic) study of rimonabant.

  12. [Multi-component quantitative analysis combined with chromatographic fingerprint for quality assessment of Onosma hookeri]. (United States)

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


    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.

  13. Extraction chromatographic separations of tantalum and tungsten from hafnium and complex matrix constituents

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Mathew S.; Finck, Martha R.; Carney, Kevin P.; Morrison, Samuel S.


    Ta, Hf, and W analyses from complex matrices (including environmental samples) require high purification of these analytes from each other and major/trace matrix constituents, however, current state-of-the-art Ta/Hf/W separations rely on traditional anion exchange approaches that suffer from relatively similar distribution coefficient (Kd) values for these analytes. This work reports assessment of three commercially available extraction chromatographic resins (TEVA, TRU, and UTEVA) for Ta/Hf/W separations. Batch contact studies show differences in Ta/W,Hf Kd values of up to 106, representing an improvement of a factor of 100 and 300 in Ta/Hf and Ta/W Kd values (respectively) over AG1x4 resin. Variations in the Kd values as a function of HCl concentration for TRU resin show that this resin is well suited for Ta/Hf/W separations, with Ta/Hf, Ta/W, and W/Hf Kd value improvements of 10, 200, and 30 (respectively) over AG1x4 resin. Finally, analyses of digested soil samples (NIST 2710a) using TRU resin and tandem TEVA-TRU columns demonstrate the ability to achieve extremely high purification (>99%) of Ta and W from each other and Hf, as well as enabling very high purification of Ta and W from the major and trace elemental constituents present in soils, using a single chromatographic step.

  14. Choline chloride-based deep eutectic solvents as additives for optimizing chromatographic behavior of caffeic acid

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guizhen; Zhu, Tao; Lei, Yingjie [Tianjin University of Technology, Tianjin (China)


    A series of deep eutectic solvents (DESs) were prepared using glycerol and choline chloride (ChCl), and Fourier transform infrared spectrometer (FT-IR) was used to analyze the spectra of glycerol, choline chloride and DESs based on glycerol and choline chloride. Then DESs were used as the additives of mobile phase to optimize chromatographic behavior of caffeic acid in high performance liquid chromatography (HPLC). A 17-run Box-Behnken design (BBD) was employed to evaluate effect of DESs as additives by analyzing the maximum theoretical plate number. Three factors, reaction temperature (60 .deg. C, 80 .deg. C, 100 .deg. C), molar ratio of glycerol and choline chloride (2 : 1, 3 : 1, 4 : 1, n/n), and volume percent of additives (0.05%, 0.10%, 0.15%, v/v), were investigated in BBD. The optimum experiment condition was that of reaction temperature (80 .deg. C), molar ratio of glycerol and ChCl (3 : 1, n/n), and volume percent of additive (0.10%, v/v). The mean chromatographic theoretical plate number of the caffeic acid this condition was 1567.5, and DESs as additives shorten the retention time and modify the chromatogram shape, proving DESs as additives for effective theoretical plate number and column efficiency in HPLC.

  15. Gas chromatographic method for the determination of lumefantrine in antimalarial finished pharmaceutical products

    Directory of Open Access Journals (Sweden)

    Sultan Suleman


    Full Text Available A simple method has been developed and validated for quantitative determination of lumefantrine in antimalarial finished pharmaceutical products using gas chromatography coupled to flame ionization detector. Lumefantrine was silylated with N,O–bis(trimethyl-silyltrifluoro-acetamide at 70°C for 30 minutes, and chromatographic separation was conducted on a fused silica capillary (HP-5, 30 m length × 0.32 mm i.d., 0.25 μm film thickness column. Evaluation of the method within analytical quality-by-design principles, including a central composite face-centered design for the sample derivatization process and Plackett–Burman robustness verification of the chromatographic conditions, indicated that the method has acceptable specificity toward excipients and degradants, accuracy [mean recovery = 99.5%, relative standard deviation (RSD = 1.0%], linearity (=0.9986, precision (intraday = 96.1% of the label claim, RSD = 0.9%; interday = 96.3% label claim, RSD = 0.9%, and high sensitivity with detection limits of 0.01 μg/mL. The developed method was successfully applied to analyze the lumefantrine content of marketed fixed-dose combination antimalarial finished pharmaceutical products.

  16. Tetanus toxoid purification: chromatographic procedures as an alternative to ammonium-sulphate precipitation. (United States)

    Stojićević, Ivana; Dimitrijević, Ljiljana; Dovezenski, Nebojša; Živković, Irena; Petrušić, Vladimir; Marinković, Emilija; Inić-Kanada, Aleksandra; Stojanović, Marijana


    Given an existing demand to establish a process of tetanus vaccine production in a way that allows its complete validation and standardization, this paper focuses on tetanus toxoid purification step. More precisely, we were looking at a possibility to replace the widely used ammonium-sulphate precipitation by a chromatographic method. Based on the tetanus toxin's biochemical characteristics, we have decided to examine the possibility of tetanus toxoid purification by hydrophobic chromatography, and by chromatographic techniques based on interaction with immobilized metal ions, i.e. chelating chromatography and immobilized metal affinity chromatography. We used samples obtained from differently fragmented crude tetanus toxins by formaldehyde treatment (assigned as TTd-A and TTd-B) as starting material for tetanus toxoid purification. Obtained results imply that purification of tetanus toxoid by hydrophobic chromatography represents a good alternative to ammonium-sulphate precipitation. Tetanus toxoid preparations obtained by hydrophobic chromatography were similar to those obtained by ammonium-sulphate precipitation in respect to yield, purity and immunogenicity. In addition, their immunogenicity was similar to standard tetanus toxoid preparation (NIBSC, Potters Bar, UK). Furthermore, the characteristics of crude tetanus toxin preparations had the lowest impact on the final purification product when hydrophobic chromatography was the applied method of tetanus toxoid purification. On the other hand, purifications of tetanus toxoid by chelating chromatography or immobilized metal affinity chromatography generally resulted in a very low yield due to not satisfactory tetanus toxoid binding to the column, and immunogenicity of the obtained tetanus toxoid-containing preparations was poor.

  17. Extraction chromatographic separations of tantalum and tungsten from hafnium and complex matrix constituents. (United States)

    Snow, Mathew S; Finck, Martha R; Carney, Kevin P; Morrison, Samuel S


    Tantalum (Ta), hafnium (Hf), and tungsten (W) analyses from complex matrices require high purification of these analytes from each other and major/trace matrix constituents, however, current state-of-the-art Ta/Hf/W separations rely on traditional anion exchange approaches that show relatively similar distribution coefficient (Kd) values for each element. This work reports an assessment of three commercially available extraction chromatographic resins (TEVA, TRU, and UTEVA) for Ta/Hf/W separations. Batch contact studies show differences in Ta/Hf and Ta/W Kd values of up to 10(6) and 10(4) (respectively), representing an improvement of a factor of 100 and 300 in Ta/Hf and Ta/W Kd values (respectively) over AG1×4 resin. Variations in the Kd values as a function of HCl concentration for TRU resin show that this resin is well suited for Ta/Hf/W separations, with Ta/Hf, Ta/W, and W/Hf Kd value improvements of 10, 200, and 30 (respectively) over AG1×4 resin. Analyses of digested soil samples (NIST 2710a) using TRU resin and tandem TEVA-TRU columns demonstrate the ability to achieve extremely high purification (>99%) of Ta and W from each other and Hf, as well as enabling very high purification of Ta and W from the major and trace elemental constituents present in soils using a single chromatographic step.

  18. Analysis of variance of designed chromatographic data sets: The analysis of variance-target projection approach. (United States)

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


    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.

  19. Linear solvation energy relationships as classifiers in non-target analysis - a gas chromatographic approach. (United States)

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


    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.

  20. Virus elimination during the purification of monoclonal antibodies by column chromatography and additional steps. (United States)

    Roberts, Peter L


    The theoretical potential for virus transmission by monoclonal antibody based therapeutic products has led to the inclusion of appropriate virus reduction steps. In this study, virus elimination by the chromatographic steps used during the purification process for two (IgG-1 & -3) monoclonal antibodies (MAbs) have been investigated. Both the Protein G (>7log) and ion-exchange (5 log) chromatography steps were very effective for eliminating both enveloped and non-enveloped viruses over the life-time of the chromatographic gel. However, the contribution made by the final gel filtration step was more limited, i.e., 3 log. Because these chromatographic columns were recycled between uses, the effectiveness of the column sanitization procedures (guanidinium chloride for protein G or NaOH for ion-exchange) were tested. By evaluating standard column runs immediately after each virus spiked run, it was possible to directly confirm that there was no cross contamination with virus between column runs (guanidinium chloride or NaOH). To further ensure the virus safety of the product, two specific virus elimination steps have also been included in the process. A solvent/detergent step based on 1% triton X-100 rapidly inactivating a range of enveloped viruses by >6 log inactivation within 1 min of a 60 min treatment time. Virus removal by virus filtration step was also confirmed to be effective for those viruses of about 50 nm or greater. In conclusion, the combination of these multiple steps ensures a high margin of virus safety for this purification process.


    Institute of Scientific and Technical Information of China (English)

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


    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.

  2. Green approach using monolithic column for simultaneous determination of coformulated drugs. (United States)

    Yehia, Ali M; Mohamed, Heba M


    Green chemistry and sustainability is now entirely encompassed across the majority of pharmaceutical companies and research labs. Researchers' attention is careworn toward implementing the green analytical chemistry principles for more eco-friendly analytical methodologies. Solvents play a dominant role in determining the greenness of the analytical procedure. Using safer solvents, the greenness profile of the methodology could be increased remarkably. In this context, a green chromatographic method has been developed and validated for the simultaneous determination of phenylephrine, paracetamol, and guaifenesin in their ternary pharmaceutical mixture. The chromatographic separation was carried out using monolithic column and green solvents as mobile phase. The use of monolithic column allows efficient separation protocols at higher flow rates, which results in short time of analysis. Two-factor three-level experimental design was used to optimize the chromatographic conditions. The greenness profile of the proposed methodology was assessed using eco-scale as a green metrics and was found to be an excellent green method with regard to the usage and production of hazardous chemicals and solvents, energy consumption, and amount of produced waste. The proposed method improved the environmental impact without compromising the analytical performance criteria and could be used as a safer alternate for the routine analysis of the studied drugs.

  3. Preparation of porous hollow silica spheres via a layer-by-layer process and the chromatographic performance (United States)

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


    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.

  4. Improved high-performance liquid chromatographic determination of khellin and visnagin in Ammi visnaga fruits and pharmaceutical formulations. (United States)

    el-Domiaty, M M


    An improved, simple, selective, and sensitive reversed-phase high-performance liquid chromatographic (HPLC) assay for khellin and visnagin in Ammi visnaga L. fruits was developed by using an internal standardized technique. The HPLC column was a reversed-phase microBondapack C18 column, the mobile phase was water: methanol:acetonitrile (49:49:2), and the flow rate was 1.5 mL/min. Khellin and visnagin were detected and analyzed with a spectrophotometer set at 250 nm. Results of the HPLC analysis indicate a relative standard deviation of less than 0.04%. The analytical procedure was used for the quantification of khellin in various pharmaceutical dosage forms, such as ampules, tablets, and suppositories, with relative standard deviations of 1.2, 1.4, and 1.7%, respectively. As little as 10 ng of khellin or visnagin could be detected accurately in less than 13 min.

  5. Gas-chromatographic determination of aluminum in catalytic systems

    Energy Technology Data Exchange (ETDEWEB)

    Astapova, T.I.; Kutepova, A.I.; Frolova, O.D.


    The authors studied conditions for the chromatographic determination of aluminum in the form of a complex with pentane-2,4-dione in pilot plant-produced samples of GIAP-16, GIAP-16-2, SPM catalysts, talums and kaolins, aluminum oxides, and hydroxides. The influence of Zn, Mg, Ca, Na, Ni, Ti, and Mn on the extraction and the chromatographic determination of aluminum was studied.

  6. Computational analysis and ratiometric comparison approaches aimed to assist column selection in hydrophilic interaction liquid chromatography-tandem mass spectrometry targeted metabolomics. (United States)

    Sampsonidis, Ioannis; Witting, Michael; Koch, Wendelin; Virgiliou, Christina; Gika, Helen G; Schmitt-Kopplin, Philippe; Theodoridis, Georgios A


    In the present work two different approaches, a semi-quantitative and a Derringer function approach, were developed to assist column selection for method development in targeted metabolomics. These approaches were applied in the performance assessment of three HILIC columns with different chemistries (an amide, a diol and a zwitterionic phase). This was the first step for the development of a HILIC UPLC-MS/MS method that should be capable to analyze a large number of polar metabolites. Two gradient elution profiles and two mobile phase pH values were tested for the analysis of multi-analyte mixtures. Acquired chromatographic data were firstly treated by a ratiometric, "semi-quantitative" approach which quantifies various overall analysis parameters (e.g. the percent of detected compounds, retentivity and resolved critical pairs). These parameters were used to assess chromatographic performance in a rather conventional/traditional and cumbersome/labor-intensive way. Secondly, a comprehensive and automated comparison of the three columns was performed by monitoring several well-known chromatographic parameters (peak width, resolution, tailing factor, etc.) using a lab-built programming script which calculates overall desirability utilizing Derringer functions. Derringer functions exhibit the advantage that column performance is ultimately expressed in an objective single and quantitative value which can be easily interpreted. In summary, results show that each column exhibits unique strengths in metabolic profiling of polar compounds. The applied methodology proved useful for the selection of the most effective chromatographic system during method development for LC-MS/MS targeted metabolomics, while it could further assist in the selection of chromatographic conditions for the development of multi-analyte methods.

  7. High performance liquid chromatographic method for the determination of cinepazide maleate and its application to a pharmacokinetic study in rats. (United States)

    Zhao, Jinyi; Song, Ying; Wang, Hujun; Sun, Yuan; Liu, Meiyou; Lu, Chengtao; Li, Yan; Wang, Shan; Zhu, Xiaohe; Hai, Wenli; Wen, Aidong; Jia, Yanyan


    A simple and reliable high performance liquid chromatographic (HPLC) method has been developed and validated to quantify cinepazide maleate, a calcium blocker, in rat plasma. Cinepazide maleate and Tinidazole (internal standard) have been extracted by a simple liquid-liquid extraction before injection into chromatographic system. Chromatographic separation was achieved on a reversed phase C18 column with a mobile phase consisted of a water mixture of 10mM potassium dihydrogen phosphate (pH=4.5):methanol (40:60, v/v), pumped at flow rate of 1.0mL/min, and detected at 303nm. The method exhibited a linear range of 0.12-120μg/mL in blank rat plasma, with the lower detection limit of 0.06μg/mL. The method was statistically validated for linearity, accuracy, precision, selectivity and stability following FDA guidelines. The intra- and inter-assay coefficients of variation did not exceed ±15% from the nominal concentration. The accuracy of cinepazide maleate was within ±15% of the theoretical value. The assay has been applied successfully in a pharmacokinetic study of cinepazide maleate after a single intravenous at three doses in rat. And cinepazide maleate injection can improve the bioavailability of cinepazide maleate greatly, and has a dose-dependence profile in rats.

  8. Development and validation of a reversed-phase liquid chromatographic method for analysis of demeclocycline and related impurities. (United States)

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


    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.

  9. Novel column-based protein refolding strategy using dye-ligand affinity chromatography based on macroporous biomaterial. (United States)

    Li, Feng; Dong, Ping-Jun; Zhuang, Qian-Fen


    A novel column-based chromatographic protein refolding strategy was developed using dye-ligand affinity chromatography (DLAC) based on macroporous biomaterial. Chitosan-silica (CS-silica) biomaterial with macroporous surface was used as the supporting matrix for the preparation of the DLAC material. The dye-ligand Cibacron Blue F3GA (CBF) was selected as affinity handle and could be covalently immobilized to form dye-ligand affinity adsorbent (CBF-CS-silica) using the reactivity of NH(2) on CS-silica biomaterial. After the model protein catalase was denatured with 6mol/L urea, the denaturant could be rapidly removed and catalase could be successfully refolded as facilitated by the adsorption of CBF-CS-silica. The urea denaturation process and the elute condition for the chromatographic refolding were optimized by measuring tryptophan fluorescence and activity of catalase. The refolding performance of the proposed DLAC was compared with dilution refolding. The protein concentration during the proposed chromatographic refolding increased by a factor of 20 without reducing the yield achieved as compared to dilution refolding. The column-based protein refolding strategy based on dye-ligand affinity chromatography with porous biomaterial being matrix possessed potential in chromatographic refolding of protein.

  10. Quantifying process tradeoffs in the operation of chromatographic sequences. (United States)

    Ngiam, Sheau-Huey; Bracewell, Daniel G; Zhou, Yuhong; Titchener-Hooker, Nigel J


    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.

  11. High-speed ion-exclusion chromatography of dissolved carbon dioxide on a small weakly acidic cation-exchange resin column with ion-exchange enhancement columns of conductivity detection. (United States)

    Mori, Masanobu; Ikedo, Mikaru; Hu, Wenzhi; Helaleh, Murad I H; Xu, Qun; Itabashi, Hideyuki; Tanaka, Kazuhiko


    The high-speed ion-exclusion chromatographic determination of dissolved carbon dioxide, i.e., carbonic acid, hydrogencarbonate or carbonate, with conductivity detection was obtained using a small column packed with a weakly acidic cation-exchange resin in the H+-form (40 mm long x 4.6 mm i.d., 3 microm-particle and 0.1 meq./ml-capacity). Two different ion-exchange resin columns, which were a strongly acidic cation-exchange resin in the K+-form and a strongly basic anion-exchange resin in the OH- -form, were connected after the separation column. The sequence of columns could convert dissolved carbon dioxide to KOH having high conductivity response. The enhancement effect for dissolved carbon dioxide could retain even on the vast chromatographic runs, by using the enhancement columns with high ion-exchange capacity above 1.0 meq./ml. The retention time was in 60 s at flow-rate of 1.2 ml/min. The calibration graph of dissolved carbon dioxide estimated as H2CO3- was linear in the range of 0.005-10 mM. The detection limit at signal to noise of 3 was 0.15 microM as H2CO3-. This method was applicable to several rainwater and tap water samples.

  12. Performance of the same column in supercritical fluid chromatography and in liquid chromatography. (United States)

    Lambert, Nándor; Felinger, Attila


    We have studied the chromatographic behavior of the homologous series of alkylbenzenes (ranging from octylbenzene to octadecylbenzene) on the same C18 reversed-phase column in supercritical fluid chromatography (SFC) and reversed phase liquid chromatography (RPLC) at various experimental conditions, such as different eluent compositions, flow-rates, and mobile phase densities. The first and the second moments of the peaks were used to estimate the overall mass-transfer processes in both chromatographic modes using the stochastic model of chromatography. The results confirm that in SFC - as the density of the mobile phase is influenced by the flow-rate - there is a broader variation of mass-transfer properties than in liquid chromatography. As expected, the optimum mobile phase velocity is higher in SFC, but there is no real difference in the minimum value of plate height, i.e. in the optimum efficiency.

  13. Micro-column solid phase extraction to determine uranium and thorium in environmental samples. (United States)

    Tsai, Tsuey-Lin; Lin, Chun-Chih; Chu, Tieh-Chi


    Extraction chromatographic separation techniques based on U/TEVA and TEVA resins were utilized to separate uranium and thorium isotopes in complex matrices from environmental samples. This approach has the advantages of ease of quantitative analysis, small sample size, an absence of mixed waste solvents, complete separation of U/Th isotopes, acceptable chemical yields and good energy resolution in the alpha spectrum. The procedure for analyzing alpha-emitting isotopes of uranium and thorium in geothermal water from Peito, Taiwan, is illustrated in detail. It involves sample pre-concentration, filtration and separation by highly selective extraction chromatographic resins, followed by electroplating and alpha-spectroscopy. The analytical results show a chemical recovery exceeding 55% for U and 65% for Th, respectively, under optimized conditions. The efficient and cost-effective use of recyclable columns makes the analytical methods simple, accurate, rapid, reliable and robust.

  14. Characterization of low molecular weight alkoxylated polymers using long column SFC/MS and an image analysis based quantitation approach. (United States)

    Pinkston, J David; Marapane, Suresh B; Jordan, Glenn T; Clair, B David


    The utility of low viscosity mobile phases and long chromatographic columns for complex polymer analysis is demonstrated. We use long column supercritical fluid chromatography/mass spectrometry (SFC/MS) with electrospray ionization (ESI) to characterize a variety of complex, low molecular weight polymers. When quantitative analysis is desired, the resulting three-dimensional (time, intensity, and mass-to-charge ratio [m/z]) data are converted to images. Custom image analysis software is used to detect and integrate peaks in arbitrarily defined regions of the time-m/z map. These integrated peak volumes can be used to quantitate distinct component classes of the polymer mixtures.

  15. Liquid chromatographic determination with fluorescence detection of B{sub 6} vitamers and riboflavin in milk and pharmaceuticals

    Energy Technology Data Exchange (ETDEWEB)

    Gatti, R. [Dipartimento di Scienze Farmaceutiche, Universita di Bologna, Via Belmeloro 6, 40126 Bologna (Italy)]. E-mail:; Gioia, M.G. [Dipartimento di Scienze Farmaceutiche, Universita di Bologna, Via Belmeloro 6, 40126 Bologna (Italy)


    A simple, reliable and selective high performance liquid chromatographic method with fluorescence detection at different programmed wavelengths has been developed for the simultaneous analysis of B{sub 6} vitamers (pyridoxal 5'-phosphate, 4-pyridoxic acid, pyridoxal, pyridoxine and pyridoxamine) and Vitamin B{sub 2} in commercial vitaminized milk and in woman milk. The chromatographic separations were performed on a reversed phase octyl column by using a mobile phase consisting of sodium pentanesulfonate in 1% acetic acid-methanol-tetrahydrofuran under gradient elution conditions. The fluorescence intensity of pyridoxal 5'-phosphate was enhanced by post-column photochemical conversion, giving significantly different fluorescence spectra by a on-line photoreactor switched OFF and ON under irradiation at 254 nm. In addition, a simple and rapid method in isocratic conditions without the need of photochemical conversion was proposed for the analysis of Vitamin B{sub 6} and Vitamin B{sub 2} in pharmaceuticals. Linearity, precision, recovery, selectivity and sensitivity were found satisfactory for each analysed compound. Quantitation limits ranged from 26 to 240 fmol.

  16. Micellar liquid chromatographic determination of sertaconazole and terconazole in bulk, pharmaceutical dosage forms and spiked human plasma

    Directory of Open Access Journals (Sweden)

    Mohamed Rizk


    Full Text Available A micellar liquid chromatographic method was developed for the determination of sertaconazole and terconazole in bulk, dosage forms and human plasma using intersil cyano column and mobile phase consisting of 0.1 M sodium dodecyl sulphate, 20% 1-propanol, and 0.3% triethylamine in 0.02 M ortho-phosphoric acid (pH 4 at 225 nm. Different chromatographic parameters were studied, e.g. types of columns, pH of mobile phase, concentration of sodium dodecyl sulphate, 1-propanol, triethylamine, etc. The method was validated over the concentration ranges 8–40 and 16–80 μg/ml, for sertaconazole and terconazole, respectively. The method was sensitive with limits of detection of 1.24 and 1.67 μg/ml for sertaconazole and terconazole in bulk, respectively. Inter and intra-day results showed % RSD < 0.9% and 1.55% for sertaconazole and terconazole, respectively. The result obtained by the proposed method was compared with that obtained by the reference HPLC technique. Furthermore, the proposed method was successfully applied as a stability-indicating method for the determination of drugs under different stressed conditions. The method showed good selectivity, repeatability, linearity and sensitivity according to the evaluation of the validation parameters.

  17. Direct chromatographic enantioresolution of fully constrained β-amino acids: exploring the use of high-molecular weight chiral selectors. (United States)

    Sardella, Roccaldo; Ianni, Federica; Lisanti, Antonella; Scorzoni, Stefania; Marini, Francesca; Sternativo, Silvia; Natalini, Benedetto


    To the best of our knowledge enantioselective chromatographic protocols on β-amino acids with polysaccharide-based chiral stationary phases (CSPs) have not yet appeared in the literature. Therefore, the primary objective of this work was the development of chromatographic methods based on the use of an amylose derivative CSP (Lux Amylose-2), enabling the direct normal-phase (NP) enantioresolution of four fully constrained β-amino acids. Also, the results obtained with the glycopeptide-type Chirobiotic T column employed in the usual polar-ionic (PI) mode of elution are compared with those achieved with the polysaccharide-based phase. The Lux Amylose-2 column, in combination with alkyl sulfonic acid containing NP eluent systems, prevailed over the Chirobiotic T one, when used under the PI mode of elution, and hence can be considered as the elective choice for the enantioseparation of this class of rigid β-amino acids. Moreover, the extraordinarily high α (up to 4.60) and R S (up to 10.60) values provided by the polysaccharidic polymer, especially when used with camphor sulfonic acid containing eluent systems, make it also suitable for preparative-scale enantioisolations.

  18. A validated stability-indicating liquid chromatographic method for the determination of retapamulin in topical dosage form. (United States)

    Nalwade, Santaji; Reddy, Vangala Ranga


    A sensitive, stability-indicating reversed-phase high-performance liquid chromatographic method is developed and validated for the quantitative determination of retapamulin in topical dosage form. The chromatographic separation is achieved by using a C18 column (XTerra RP 18 250 × 4.6 mm, 5 µm) at 30°C. The mobile phase comprises a mixture of 0.05M potassium dihydrogen phosphate buffer (pH 6.1), acetonitrile and methanol in the ratio of 35:50:15 (v/v/v). The flow rate is set at 1.0 mL/min and chromatograms are extracted at 243 nm using a photodiode array detector. The method is validated with respect to linearity, accuracy, precision, robustness and forced degradation studies, which further prove the stability-indicating supremacy of the method. During forced degradation studies, retapamulin is observed to be labile to oxidative and base hydrolysis stress and stable in thermal, photolytic and acid hydrolysis stress. The degradation products are well separated from the retapamulin peak, thus proving the stability-indicating superiority of the method. The method is found to be sensitive for retapamulin, with a detection limit of 25 ng/mL and a quantification limit of 80 ng/mL. The proposed method is found to be very sensitive and accurate for the determination of retapamulin in topical dosage form. The method is also demonstrated to be robust, because it is resistant to small variations of chromatographic variables such as pH, mobile phase composition, flow rate and column temperature.

  19. Effect of Coriolis force on counter-current chromatographic separation by centrifugal partition chromatography. (United States)

    Ikehata, Jun-Ichi; Shinomiya, Kazufusa; Kobayashi, Koji; Ohshima, Hisashi; Kitanaka, Susumu; Ito, Yoichiro


    The effect of Coriolis force on the counter-current chromatographic separation was studied using centrifugal partition chromatography (CPC) with four different two-phase solvent systems including n-hexane-acetonitrile (ACN); tert-butyl methyl ether (MtBE)-aqueous 0.1% trifluoroacetic acid (TFA) (1:1); MtBE-ACN-aqueous 0.1% TFA (2:2:3); and 12.5% (w/w) polyethylene glycol (PEG) 1000-12.5% (w/w) dibasic potassium phosphate. Each separation was performed by eluting either the upper phase in the ascending mode or the lower phase in the descending mode, each in clockwise (CW) and counterclockwise column rotation. Better partition efficiencies were attained by the CW rotation in both mobile phases in all the two-phase solvent systems examined. The mathematical analysis also revealed the Coriolis force works favorably under the CW column rotation for both mobile phases. The overall results demonstrated that the Coriolis force produces substantial effects on CPC separation in both organic-aqueous and aqueous-aqueous two-phase systems.

  20. An improved ion chromatographic method for determination of trace levels of perchlorate in environmental water

    Institute of Scientific and Technical Information of China (English)


    An improved ion chromatographic (IC)method was developed to determine trace levels of perchlorate in environmental water samples.Perchlorate was separated in the hydroxide selective column IonPac AS 16 using NaOH as an eluent with an organic modifier.To eliminate the coelution of perchlorate and 4-chlorobenzene sulfonate (4-CBS),an organic solvent as modifier was added to the eluent.Of four organic solvents studied,acetonitrile proved to be the most efficient based on the retention time of perchlorate and 4-CBS.To improve the method sensitivity,a concentrator column (AGI9) was used to concentrate perchlorate online.With the adoption of a preconcentration step,the sensitivity of our method was improved and the method detection limit (MDL) was reduced to 0.1 μg/L.The linear range was from 0.2 μg/L to 200/.μg/L with a linear correlation coefficient of 0.9989 and the relative standard deviation (RSD) of peak area for eleven successive injections of 0.5 μg/L perehlorate was 4.2%.The method had been applied to the determination of perchlorate in some real environmental water samples and recovery was between 93% and 113%.

  1. High-performance liquid chromatographic analysis and pharmacokinetics of terazosin in healthy volunteers. (United States)

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


    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.

  2. Modeling of the simulated countercurrent moving-bed chromatographic reactor used for the oxidative coupling of methane

    Energy Technology Data Exchange (ETDEWEB)

    Tonkovich, A.L.Y. [Pacific Northwest Lab., Richland, WA (United States); Carr, R.W. [Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Chemical Engineering and Materials Sciences


    The oxidative coupling reaction of methane (OCM) is a potential industrial reaction for the efficient production of ethylene. Replacement of current technologies requires significant product yield improvements. An experimental novel reactor design, the modified simulated countercurrent moving-bed chromatographic reactor (SCMCR), has reported improved ethane and ethylene product yields over other reported values. An understanding of the reactor operation is aided by concurrent mathematical modeling. The model mimics the exact experimental reactor configuration. Four sections are used; each section contains a reaction column and two separation columns connected in series. The feed is switched from section to section at discrete intervals. Reaction occurs in the first column and is followed by product and reactant separation in the ensuing section columns. Langmuir adsorption isotherms are used. The model does not incorporate the realistic and complex kinetics rising, from the OCM, rather a simplified reaction term is used to qualitatively gain insight into the operation of the modified SCMCR. A unimolecular reaction network is used in the model. The rate constants are set to permit a small fractional conversion, 5% per pass, at the concentrations during the first cycle. Similarly to the experimental reactor, the model adds a make-up feed (defined as percentage of the original feed, where excess methane is fed during the first cycle of the experimental reactor) to augment lost reactants.

  3. Post-synthetic modification of MIL-101(Cr) with pyridine for high-performance liquid chromatographic separation of tocopherols. (United States)

    Yang, Fang; Yang, Cheng-Xiong; Yan, Xiu-Ping


    Effective separation of tocopherols is challenging and significant due to their structural similarity and important biological role. Here we report the post-synthetic modification of metal-organic framework (MOF) MIL-101(Cr) with pyridine for high-performance liquid chromatographic (HPLC) separation of tocopherols. Baseline separation of four tocopherols was achieved on a pyridine-grafted MIL-101(Cr) packed column within 10 min using hexane/isopropanol (96:4, v/v) as the mobile phase at a flow rate of 0.5 mL min(-1). The pyridine-grafted MIL-101(Cr) packed column gave high column efficiency (85,000 plates m(-1) for δ-tocopherol) and good precision (0.2-0.3% for retention time, 1.8-3.4% for peak area, 2.6-2.7% for peak height), and also offered much better performance than unmodified MIL-101(Cr) and commercial amino-bonded silica packed column for HPLC separation of tocopherols. The results not only show the promising application of pyridine-grafted MIL-101(Cr) as a novel stationary phase for HPLC separation of tocopherols, but also reveal a facile post-modification of MOFs to expand the application of MOFs in separation sciences.

  4. [Influences of the mobile phase constitution, salt concentration and pH value on retention characters of proteins on the metal chelate column]. (United States)

    Li, R; Di, Z M; Chen, G L


    The effects of the nature and concentration of salts, pH value and competitive eluent in the mobile phase on the protein retention have been systematically investigated. A mathematical expression describing the protein retention in metal chelate chromatography has been derived. It is proposed that the eluting power of the salt solution can be expressed by the eluent strength exponent epsilon. According to the retention characters of protein under different chromatographic conditions, the interaction between the various metal chelate ligands and proteins is discussed. The protein retention on the metal chelate column is a cooperative interactions of coordination, electrostatic and hydrophobic interaction. For the strong combined metal column with proteins such as IDA-Cu, the coordination is the most important, and the electrostatic interaction is secondary in chromatographic process. However, for the weak combined metal columns with proteins such as IDA-Ni, IDA-Co and IDA-Zn, the electrostatic interaction between the metal chelate ligands and proteins is the chief one, while the coordination is the next in importance. When the mobile phase contains high concentration of salt which can't form complex with the immobilized metal, the hydrophobic interaction between the protein and stationary phase will be increased. As the interaction between the metal chelate ligand and proteins relates to chromatographic operating conditions closely, different elution processes may be selected for different metal chelate columns. The gradient elution is generally performed by the low concentration of salt or different pH for weakly combined columns with proteins, however the competitive elution procedure is commonly utilized for strongly combined column. The experiment showed that NH3 is an excellent competitive eluent. It isn't only give the efficient separation of proteins, but also has the advantages of cheapness, less bleeding of the immobilized metals and ease of controlling NH3

  5. Column Holdup Formula of Soil Solute Transport

    Institute of Scientific and Technical Information of China (English)


    The shortcomings of the present two formulae for describing column holdup are analyzed and deductions are made to find a new formula. The column holdup, Hw, described by the new formula is dimensional,and related to soil solute transport kinesis and column physical properties. Compared with the other two column holdups, Hw is feasible to describe dimensional column holdup during solute transport process. The relationships between Hw and retardation factor, R, in different solute transport boundary conditions are established.

  6. Profiling of triacylglycerols in plant oils by high-performance liquid chromatography-atmosphere pressure chemical ionization mass spectrometry using a novel mixed-mode column. (United States)

    Hu, Na; Wei, Fang; Lv, Xin; Wu, Lin; Dong, Xu-Yan; Chen, Hong


    In this investigation, a rapid and high-throughput method for profiling of TAGs in plant oils by liquid chromatography using a single column coupled with atmospheric pressure chemical ionization (APCI) mass spectrometry was reported. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this separation system. The phenyl-hexyl column could provide hydrophobic interactions as well as π-π interactions. Compared with two traditionally columns used in TAG separation - the C18 column and silver-ion column, this column exhibited much higher selectivity for the separation of TAGs with great efficiency and rapid speed. By comparison with a novel mix-mode column (Ag-HiSep OTS column), which can also provide both hydrophobic interactions as well as π-π interactions for the separation of TAGs, phenyl-hexyl column exhibited excellent stability. LC method using phenyl-hexyl column coupled with APCI-MS was successfully applied for the profiling of TAGs in soybean oils, peanut oils, corn oils, and sesame oils. 29 TAGs in peanut oils, 22 TAGs in soybean oils, 19 TAGs in corn oils, and 19 TAGs in sesame oils were determined and quantified. The LC-MS data was analyzed by barcodes and principal component analysis (PCA). The resulting barcodes constitute a simple tool to display differences between different plant oils. Results of PCA also enabled a clear identification of different plant oils. This method provided an efficient and convenient chromatographic technology for the fast characterization and quantification of complex TAGs in plant oils at high selectivity. It has great potential as a routine analytical method for analysis of edible oil quality and authenticity control.

  7. Tunable separation of anions and cations by column switching in ion chromatography. (United States)

    Amin, Muhammad; Lim, Lee Wah; Takeuchi, Toyohide


    A convenient ion chromatography method has been proposed for the routine and simple determination of anions (Cl(-), SO(4)(2-) and NO(3)(-)) and/or cations (Na(+), NH(4)(+), K(+), Mg(2+) and Ca(2+)) using a single pump, a single eluent and a single detector. The present system used cation-exchange and anion-exchange columns connected in series via two 6-port switching valves or a single 10-port valve. The connection order of the ion-exchange columns could be varied by switching the valve(s). The present system therefore allowed the separation of either cations or anions in a single chromatographic run. While one ion-exchange column is being operated, the other ion-exchange column is being conditioned, i.e., the columns are always ready for analysis at any time. When 2.4mM 5-sulfosalicylic acid was used as the eluent, the three anions and the five cations could be separated on the anion-exchange column and cation-exchange column, respectively. In order to obtain the separations of the target ions, the injection valve was placed between the two columns. Complete separations of the above anions or cations were demonstrated within 10min each. The detection limits at S/N=3 were 19-50ppb (mug/l) for cations and 10-14ppb for anions. The relative standard deviations of the analyte ions were less than 1.1, 2.9 and 2.8% for retention time, peak area and peak height, respectively. This proposed technique was applied to the determination of common anions and cations in river water samples.

  8. Partial least squares model and design of experiments toward the analysis of the metabolome of Jatropha gossypifolia leaves: Extraction and chromatographic fingerprint optimization. (United States)

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


    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.

  9. Development of Chromatographic Fingerprints of Eurycoma longifolia (Tongkat Ali) Roots Using Online Solid Phase Extraction-Liquid Chromatography (SPE-LC). (United States)

    Zaini, Nor Nasriah; Osman, Rozita; Juahir, Hafizan; Saim, Norashikin


    E. longifolia is attracting interest due to its pharmacological properties and pro-vitality effects. In this study, an online SPE-LC approach using polystyrene divinyl benzene (PSDVB) and C18 columns was developed in obtaining chromatographic fingerprints of E. longifolia. E. longifolia root samples were extracted using pressurized liquid extraction (PLE) technique prior to online SPE-LC. The effects of mobile phase compositions and column switching time on the chromatographic fingerprint were optimized. Validation of the developed method was studied based on eurycomanone. Linearity was in the range of 5 to 50 µg∙mL(-1) (r² = 0.997) with 3.2% relative standard deviation of peak area. The developed method was used to analyze 14 E. longifolia root samples and 10 products (capsules). Selected chemometric techniques: cluster analysis (CA), discriminant analysis (DA), and principal component analysis (PCA) were applied to the fingerprint datasets of 37 selected peaks to evaluate the ability of the chromatographic fingerprint in classifying quality of E. longifolia. Three groups were obtained using CA. DA yielded 100% correlation coefficient with 19 discriminant compounds. Using PCA, E. longifolia root samples were clearly discriminated from the products. This study showed that the developed online SPE-LC method was able to provide comprehensive evaluation of E. longifolia samples for quality control purposes.

  10. Development and validation of an ultra high-performance liquid chromatographic method for the determination of a diastereomeric impurity in (+)-pinoresinol diglucoside chemical reference substance. (United States)

    Song, Jing-Zheng; Cheung, Lok Man; Liu, Xin; Qiao, Chun-Feng; Zhou, Yan; Li, Song-Lin; Chen, Shi-Lin; Xu, Hong-Xi


    (+)-Pinoresinol 4,4'-di-O-beta-D-glucopyranoside ((+)-PDG) is one of the major lignans with various pharmacological activities which could be isolated from Duzhong and other plant species. In this study, a diastereomeric impurity, (-)-pinoresinol 4,4'-di-O-beta-D-glucopyranoside ((-)-PDG), the main impurity was identified in (+)-PDG chemical reference substance (CRS) and a reliable chromatographic method for rapid purity determination of (+)-PDG CRS was firstly developed. The optimal chromatographic condition was found to be using ACN/1,4-dioxane-water (2.5:6:91.5, v/v/v) as mobile phase on a Waters Acquity UPLC HSS T3 column (2.1 mm x 100 mm, 1.8 microm) with column temperature of 37 degrees C. The method was validated and applied to determine the chromatographic purity of five (+)-PDG CRS samples. The content of (-)-PDG in four commercial (+)-PDG CRS was 8.47-20.30%, whereas no (-)-PDG was detected in our in-house prepared (+)-PDG CRS in which purity was confirmed to be 99.80%. The above results confirmed that this method is fast and highly efficient for purity determination of the (+)-PDG CRS.

  11. QbD-oriented development and validation of a bioanalytical method for nevirapine with enhanced liquid-liquid extraction and chromatographic separation. (United States)

    Beg, Sarwar; Chaudhary, Vandna; Sharma, Gajanand; Garg, Babita; Panda, Sagar Suman; Singh, Bhupinder


    The present studies describe the systematic quality by design (QbD)-oriented development and validation of a simple, rapid, sensitive and cost-effective reversed-phase HPLC bioanalytical method for nevirapine in rat plasma. Chromatographic separation was carried out on a C18 column using isocratic 68:9:23% v/v elution of methanol, acetonitrile and water (pH 3, adjusted by orthophosphoric acid) at a flow rate of 1.0 mL/min using UV detection at 230 nm. A Box-Behnken design was applied for chromatographic method optimization taking mobile phase ratio, pH and flow rate as the critical method parameters (CMPs) from screening studies. Peak area, retention time, theoretical plates and peak tailing were measured as the critical analytical attributes (CAAs). Further, the bioanalytical liquid-liquid extraction process was optimized using an optimal design by selecting extraction time, centrifugation speed and temperature as the CMPs for percentage recovery of nevirapine as the CAA. The search for an optimum chromatographic solution was conducted through numerical desirability function. Validation studies performed as per the US Food and Drug Administration requirements revealed results within the acceptance limit. In a nutshell, the studies successfully demonstrate the utility of analytical QbD approach for the rational development of a bioanalytical method with enhanced chromatographic separation and recovery of nevirapine in rat plasma. Copyright © 2015 John Wiley & Sons, Ltd.

  12. Columns

    Institute of Scientific and Technical Information of China (English)

    Carrie Tsang; 丁燕燕; 韩多妮; RAY


    <正>Paris承诺的展现33岁的墨西哥艺术家Mario Garcia Torres是近年国际艺坛炙手可热的新星,他以录象、摄影、幻灯及装置为创作形式,透过个人视点及独特演绎手法来重新思考历史。他是一个思考型艺术家,同时又是一个淘气的大孩子,作品往往反映了他的双重性格——嬉戏中带有深沉的历史感。这次是GarciaTorres首次在法国的国家博物馆举行展览,整合出版了他过往两年间在

  13. Columns

    Institute of Scientific and Technical Information of China (English)

    于晓悠; 丁燕燕; 韩多妮; Ray; Carrie; 未冉


    <正>New York Whitney艺术双年展今年第75届纽约Whitney双年展不设题目,但以"2010"指示策展方向,继续以发掘年轻艺术家、展示创作实验为目标。参展的55位艺术家,最年轻的是23岁摄影师Tam Tran,最老资历的是75岁的概念艺术家Lorraine O’Grady。这届的另一先创性,是每位艺术家只限一件或一个系列的作品,避免了去届双年展的"小型个人回顾展"现象,而五层楼的展场各有特色,如录像及短片将独立于三楼展出,而美术馆馆藏则移师五楼。这届双年展由著名的意大利策展人Francesco Bonami联同助手Gary Carrion-Murayarn共同制作,两位策展人说明,双年展的重要性是预示未来,创新及前瞻性依然是取决原则。

  14. Continuous melting and ion chromatographic analyses of ice cores. (United States)

    Huber, T M; Schwikowski, M; Gäggele, H W


    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.

  15. Physicochemical and chromatographic method of characterization of Matricaria recutita tinctures

    Directory of Open Access Journals (Sweden)

    Jonathan Parra


    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.

  16. Mathematical functions for the representation of chromatographic peaks. (United States)

    Di Marco, V B; Bombi, G G


    About ninety empirical functions for the representation of chromatographic peaks have been collected and tabulated. The table, based on almost 200 references, reports for every function: (1) the most used name; (2) the most convenient equation, with the existence intervals for the adjustable parameters and for the independent variable; (3) the applications; (4) the mathematical properties, in relation to the possible applications. The list includes also equations originally proposed to represent peaks obtained in other analytical techniques (e.g. in spectroscopy), which in many instances have proved useful in representing chromatographic peaks as well; the built-in functions employed in some commercial peak-fitting software packages were included, too. Some of the most important chromatographic functions, i.e. the Exponentially Modified Gaussian, the Poisson, the Log-normal, the Edgeworth/Cramér series and the Gram/Charlier series, have been reviewed and commented in more detail.

  17. Recent advances in the preparation and application of monolithic capillary columns in separation science

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Tingting; Yang, Xi; Xu, Yujing [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing, 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing, 210009 (China); Ji, Yibing, E-mail: [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing, 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing, 210009 (China)


    Novel column technologies involving various materials and efficient reactions have been investigated for the fabrication of monolithic capillary columns in the field of analytical chemistry. In addition to the development of these miniaturized systems, a variety of microscale separation applications have achieved noteworthy results, providing a stepping stone for new types of chromatographic columns with improved efficiency and selectivity. Three novel strategies for the preparation of capillary monoliths, including ionic liquid-based approaches, nanoparticle-based approaches and “click chemistry”, are highlighted in this review. Furthermore, we present the employment of state-of-the-art capillary monolithic stationary phases for enantioseparation, solid-phase microextraction, mixed-mode separation and immobilized enzyme reactors. The review concludes with recommendations for future studies and improvements in this field of research. - Highlights: • Preparation of novel monolithic capillary columns have shown powerful potential in analytical chemistry field. • Various materials including ionic liquids and nanoparticles involved into capillary monolithic micro-devices are concluded. • Click chemistry strategy applied for preparing monolithic capillary columns is reviewed. • Recent strategies utilized in constructing different capillary monoliths for enantiomeric separation are summarized. • Advancement of capillary monoliths for complex samples analysis is comprehensively described.

  18. Simultaneous determination of iodide and iodate in povidone iodine solution by ion chromatography with homemade and exchange capacity controllable columns and column-switching technique. (United States)

    Huang, Zhongping; Zhu, Zuoyi; Subhani, Qamar; Yan, Wenwu; Guo, Weiqiang; Zhu, Yan


    A simple ion chromatographic method for simultaneous detection of iodide and iodate in a single running was proposed, with columns packed with homemade functionalized polystyrene-divinylbenzene (PS-DVB) resins and column-switching technique. Homemade resins were functionalized with controllable amounts of quaternary ammonium groups. The low-capacity anion-exchange column and high-capacity anion-exchange column were prepared, due to the resins having different exchange capacities. With this method, iodide and iodate in povidone iodine solution were detected simultaneously in a short time with iodide being eluted off first. A series of standard solutions consisting of target anions of various concentrations from 0.01 mg/L to 100 mg/L were analyzed. Each anion exhibited satisfactory linearity, with correlation coefficient r ≥ 0.9990. The detection limits (LODs) for iodide and iodate obtained by injecting 100 μL of sample were 5.66 and 14.83 μg/L (S/N=3), respectively. A spiking study was performed with satisfactory recoveries between 101.2% and 100.6% for iodide and iodate.

  19. Modeling of column apparatus processes

    CERN Document Server

    Boyadjiev, Christo; Boyadjiev, Boyan; Popova-Krumova, Petya


    This book presents a new approach for the modeling of chemical and interphase mass transfer processes in industrial column apparatuses, using convection-diffusion and average-concentration models. The convection-diffusion type models are used for a qualitative analysis of the processes and to assess the main, small and slight physical effects, and then reject the slight effects. As a result, the process mechanism can be identified. It also introduces average concentration models for quantitative analysis, which use the average values of the velocity and concentration over the cross-sectional area of the column. The new models are used to analyze different processes (simple and complex chemical reactions, absorption, adsorption and catalytic reactions), and make it possible to model the processes of gas purification with sulfur dioxide, which form the basis of several patents.

  20. Beam Studies with Electron Columns

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, V.; Valishev, A.; Kuznetsov, G.; /Fermilab; Kamerdzhiev, V.; /Julich, Forschungszentrum; Romanov, A.; /Novosibirsk, IYF


    We report preliminary results of experimental studies of 'electron columns' in the Tevatron and in a specialized test setup. In the Tevatron, a beam of 150 GeV protons ionizes residual gas and ionization electrons are stored in an electrostatic trap immersed into strong longitudinal magnetic field. Shifts of proton betatron frequencies are observed. In the test setup, we observe effects pointing to accumulation and escape of ionization electrons.

  1. Developments and applications of microfluidic chip-based chromatographic technique%基于微流控芯片的色谱技术的研究进展及其应用

    Institute of Scientific and Technical Information of China (English)

    王新珏; 祝莹; 方群


    Microfluidic chip-based chromatographic technique has undergone rapid progress in recent years. The progress in the fabrication of chromatographic columns , the design of valves and pumps, the integration of these components into a single chip and the applications of the chip-based chromatographic systems. are reviewed, and 66 references are cited.%近年来.基于微流控芯片的色谱技术研究取得了快速发展.本文对微流控芯片上色谱柱的加工方法、泵阀驱动控制装置的设计、集成及联用色谱系统的研制及其应用等方面予以综述,涉及文献66篇.

  2. Water Column Methylation in Estuaries (United States)

    Schartup, A. T.; Calder, R.; Soerensen, A. L.; Mason, R. P.; Balcom, P. H.; Sunderland, E. M.


    Methylmercury (MeHg) is a neurotoxin that bioaccumulates in aquatic food webs and affects humans and wildlife through fish consumption. Many studies have measured active methylation/demethylation in ocean margin sediments but few have reported similar rates for the marine water column. This presentation will review available evidence for water column methylation in estuaries, including new experimental measurements of methylation/demethylation rates from a deep subarctic fjord in Labrador Canada collected in Spring and Fall of 2012-2013. We used these and other data to construct a mass budget for MeHg in the estuary and show that water column methylation (with rates ranging from 1.5 to 2.8 % day-1), is the largest contributor, followed by inputs from rivers (4.9 mol year-1), to the in situ pool of MeHg available for uptake by biota. By contrast, the sediment in this system is a net sink for MeHg (-1.5 mol year-1). We discuss the relationship between observed MeHg and other ancillary environmental factors (organic carbon, sulfur and nutrients) as well as implications for the response time of fish to future changes in mercury inputs.

  3. Non-targeted chromatographic analyses of cuticular wax flavonoids from Physalis alkekengi L. (United States)

    Kranjc, Eva; Albreht, Alen; Vovk, Irena; Makuc, Damjan; Plavec, Janez


    Since Chinese lantern (Physalis alkekengi L.) represents a rich source of various bioactive secondary metabolites, there is an urge for its detailed characterization. Non-polar flavonoid aglycones represent one of the few bioactive species found in plant's cuticular waxes. The separation of flavonoids is already extensively covered in the literature, but methods dedicated to separation and identification of methylated flavonoids are rather scarce. In the present study a non-targeted approach for the separation, isolation and identification of methylated flavonoids present in P. alkekengi L. var. franchetii cuticular waxes was established. A rapid and simple separation on HPTLC silica gel was developed for preliminary screening of flavonoids. Fast HPLC-UV-MS(n) and HPLC-UV methods using a C6-Phenyl and a C18 stationary phase were also developed, respectively. In both cases, the right combination of temperature and tetrahydrofuran, as a mobile phase modifier, were shown to be crucial for a baseline separation of all studied compounds. By employing a semi-preparative analog of the C18 column, a simultaneous isolation of pure unknown analytes was achieved. Using these developed methods in combination with NMR, four 3-O-methylated flavonols were detected and identified in P. alkekengi L. var. franchetii cuticular waxes: myricetin 3,7,3'-trimethyl ether, quercetin 3,7-dimethyl ether, myricetin 3,7,3',5'-tetramethyl ether and quercetin 3,7,3'-trimethyl ether. Moreover, the simple and fast isocratic HPLC-UV-MS(n) method (under 8min) should prove useful in quality control of P. alkekengi L. var. franchetii by enabling chromatographic fingerprinting of external methylated flavonols. Finally, a rationale for the mechanism of separation of these metabolites by HPLC is also given, which establishes a foundation for future development of chromatographic methods for methylated flavonols and related compounds.

  4. Chromatographic fingerprinting as a strategy to identify regulated plants in illegal herbal supplements. (United States)

    Custers, D; Van Praag, N; Courselle, P; Apers, S; Deconinck, E


    Erectile dysfunction (ED) is a sexual disorder characterized by the inability to achieve or maintain a sufficiently rigid erection. Despite the availability of non-invasive oral treatment options, many patients turn to herbal alternatives. Furthermore, herbal supplements are increasingly gaining popularity in industrialized countries and, as a consequence, quality control is a highly important issue. Unfortunately, this is not a simple task since plants are often crushed and mixed with other plants, which complicates their identification by usage of classical approaches such as microscopy. The aim of this study was to explore the potential use of chromatographic fingerprinting to identify plants present in herbal preparations intended for the treatment of ED. To achieve this goal, a HPLC-PDA and a HPLC-MS method were developed, using a full factorial experimental design in order to acquire characteristic fingerprints of three plants which are potentially beneficial for treating ED: Epimedium spp., Pausinystalia yohimbe and Tribulus terrestris. The full factorial design demonstrated that for all three plant references a C8 column (250mm×4.6mm; 5µm particle size) is best suited; methanol and an ammonium formate buffer (pH 3) were found to be the best constituents for the mobile phase. The suitability of this strategy was demonstrated by analysing several self-made triturations in three different botanical matrices, which mimic the influential effects that could be expected when analysing herbal supplements. To conclude, this study demonstrates that chromatographic fingerprinting could provide a useful means to identify plants in a complex herbal mixture.

  5. Study of ion chromatographic behavior of inorganic and organic antimony species by using inductively coupled plasma mass spectrometric (ICP-MS) detection

    Energy Technology Data Exchange (ETDEWEB)

    Ulrich, N. [University of Hannover, Department of Inorganic Chemistry (Germany)


    An on-line method for the analysis of Sb(III), Sb(V) and trimethylstiboxide (TMSbO) is presented. The separation is performed using ion chromatography (IC) on a strong anion-exchange column with phthalic acid plus 2% acteone at pH 5 as mobile phase. The chromatographic system is coupled to an ICP-MS as detector. The influence of different complexing agents on the chromatographic behavior of the antimony species is studied. Rather stable complexes of Sb(III) seem to be formed with citrate and tartrate under the experimental conditions. TMSbO forms a dianionic species with citrate in contrast to the otherwise monoanionic complex. (orig.) With 3 figs., 2 tabs., 8 refs.

  6. Metal-Organic Framework Thin Films as Stationary Phases in Microfabricated Gas-Chromatography Columns.

    Energy Technology Data Exchange (ETDEWEB)

    Read, Douglas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sillerud, Colin Halliday [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    The overarching goal of this project is to integrate Sandia's microfabricated gas-chromatography ( GC) columns with a stationary phase material that is capable of retaining high-volatility chemicals and permanent gases. The successful integration of such a material with GCs would dramatically expand the repertoire of detectable compounds for Sandia's various microanalysis systems. One such promising class of candidate materials is metal-organic frameworks (MOFs). In this report we detail our methods for controlled deposition of HKUST-1 MOF stationary phases within GC columns. We demonstrate: the chromatographic separation of natural gas; a method for determining MOF film thickness from chromatography alone; and the first-reported GC x GC separation of natural gas -- in general -- let alone for two disparate MOF stationary phases. In addition we determine the fundamental thermodynamic constant for mass sorption, the partition coefficient, for HKUST-1 and several light hydrocarbons and select toxic industrial chemicals.

  7. Evaluation of fructooligosaccharides separation using a fixed-bed column packed with activated charcoal. (United States)

    Kuhn, Raquel Cristine; Mazutti, Marcio A; Albertini, Lilian Buoro; Filho, Francisco Maugeri


    Recent studies have shown that the chromatographic separation of mixtures of saccharides may be improved by making use of activated charcoal, a promising low cost material for the separation of sugars, including fructooligosaccharides. In this work, the development of a methodology to separate fructooligosaccharides from glucose, fructose and sucrose, using a fixed bed column packed with activated charcoal is proposed. The influence of temperature, eluant concentration and step gradients were evaluated to increase the separation efficiency and fructooligosaccharide purity. The final degree of fructooligosaccharide purification and separation efficiency were about 94% and 3.03 respectively, using ethanol gradient concentration ranging from 3.5% to 15% (v/v) at 40°C. The fixed bed column packed with the activated charcoal was shown to be a promising alternative for sugar separation, mainly those rich in fructooligosaccharides, leading to solutions of acceptable degrees of purification.

  8. A new method for the determination of peak distribution across a two-dimensional separation space for the identification of optimal column combinations. (United States)

    Leonhardt, Juri; Teutenberg, Thorsten; Buschmann, Greta; Gassner, Oliver; Schmidt, Torsten C


    For the identification of the optimal column combinations, a comparative orthogonality study of single columns and columns coupled in series for the first dimension of a microscale two-dimensional liquid chromatographic approach was performed. In total, eight columns or column combinations were chosen. For the assessment of the optimal column combination, the orthogonality value as well as the peak distributions across the first and second dimension was used. In total, three different methods of orthogonality calculation, namely the Convex Hull, Bin Counting, and Asterisk methods, were compared. Unfortunately, the first two methods do not provide any information of peak distribution. The third method provides this important information, but is not optimal when only a limited number of components are used for method development. Therefore, a new concept for peak distribution assessment across the separation space of two-dimensional chromatographic systems and clustering detection was developed. It could be shown that the Bin Counting method in combination with additionally calculated histograms for the respective dimensions is well suited for the evaluation of orthogonality and peak clustering. The newly developed method could be used generally in the assessment of 2D separations. Graphical Abstract ᅟ.

  9. Chromatographic separation of alkaline phosphatase from dental enamel

    DEFF Research Database (Denmark)

    Moe, D; Kirkeby, S; Salling, E


    Alkaline phosphatase (AP) was prepared from partly mineralized bovine enamel by extraction in phosphate buffer, centrifugation and various chromatographic techniques. Chromatofocusing showed that the enamel enzyme possessed five isoelectric points at the acid pH level ranging from pH 5.7 to pH 4....

  10. On the ion chromatographic determination of S(IV) (United States)

    Dasgupta, Purnendu K.

    Ion Chromatographie determination of S(IV) is described with special reference to the determination of SO 2(g) and/or aerosol S(IV) along with chloride, nitrate and sulfate in particulate matter. A method is presented for the baseline separation of the above species. The Chromatographic behavior of hydroxymethanesulfonate under various eluent conditions is discussed.

  11. Chromatographic fingerprints analysis for evaluation of Ginkgo Biloba products (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...

  12. Chromatographic profiles of Ginkgo biloba leaves and selected products (United States)

    An LC-DAD-ESI/MS method was developed to obtain chromatographic profiles for the flavonoids and terpene lactones of Ginkgo biloba leaves and selected G. biloba products. The method was used to identify 46 glycosylated flavonols and flavones, 3 free flavonol aglycones, catechin, 10 biflavones, a dihy...

  13. Note on the chromatographic analyses of marine polyunsaturated fatty acids (United States)

    Schultz, D.M.; Quinn, J.G.


    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.

  14. Optimizing Chromatographic Separation: An Experiment Using an HPLC Simulator (United States)

    Shalliker, R. A.; Kayillo, S.; Dennis, G. R.


    Optimization of a chromatographic separation within the time constraints of a laboratory session is practically impossible. However, by employing a HPLC simulator, experiments can be designed that allow students to develop an appreciation of the complexities involved in optimization procedures. In the present exercise, a HPLC simulator from "JCE…

  15. Chromatographic performance of synthetic polycrystalline diamond as a stationary phase in normal phase high performance liquid chromatography. (United States)

    Peristyy, Anton; Paull, Brett; Nesterenko, Pavel N


    The chromatographic properties of high pressure high temperature synthesised diamond (HPHT) are investigated in normal phase mode of high performance liquid chromatography. Purified nonporous irregular shape particles of average particles size 1.2 μm and specific surface area 5.1 m(2) g(-1) were used for packing 100×4.6 mm ID or 50×4.6 mm ID stainless steel columns. The retention behaviour of several classes of compounds including alkyl benzenes, polyaromatic hydrocarbons (PAH), alkylphenylketones, phenols, aromatic acids and bases were studied using n-hexane-2-propanol mixtures as mobile phase. The results are compared with those observed for microdispersed sintered detonation nanodiamond (MSDN) and porous graphitic carbon (PGC). HPHT diamond revealed distinctive separation selectivity, which is orthogonal to that observed for porous graphitic carbon; while selectivities of HPHT diamond and microdispersed sintered detonation nanodiamonds are similar. Owing to non-porous particle nature, columns packed with high pressure high temperature diamond exhibited excellent mass transfer and produce separations with maximum column efficiency of 128,200 theoretical plates per meter.

  16. Preparation of Immobilized Metal Affinity Chromatographic Packings Based on Monodisperse Hydrophilic Non-porous Beads and Their Application

    Institute of Scientific and Technical Information of China (English)

    BO Chun-Miao; GONG Bo-Lin; HU Wen-Zhi


    Three hydrophilic immobilized metal affinity chromatographic packings for HPLC have been synthesized by chemical modification of 3.0 μm monodisperse non-porous poly(glycidyl methacrylate-co-ethylenedimethacrylate)(PGMMEDMA)beads.The retention behavior of proteins on the metal ion chelated columns loaded with copper(Ⅱ),nickel(Ⅱ)and zin(Ⅱ)ion was studied.The effect of pH on the protein retention Was investigated on both the naked and metal ion chelated columns in the range from 4.0 to 9.0.Four proteins were quickly separated in 3.0 min with linear gradient elution at a flow rate of 3.0 mL/min by using the synthesized Ni2+ -IDA(iminodiacetic acid)packings.The separation time was shorter than other immobilized metal affinity chromatography reported in the literature.Purification of lysozyme from egg white and trypsin on the commercially available trypsin was performed on the naked-IDA and Cu2+ -IDA columns,respectively.The purities of the purified trypsin and lysozyme were more than 92%and 95%,respectively.

  17. [Development of an automatic vacuum liquid chromatographic device and its application in the separation of the components from Schisandra chinensis (Turz) Baill]. (United States)

    Zhu, Jingbo; Liu, Baoyue; Shan, Shibo; Ding, Yanl; Kou, Zinong; Xiao, Wei


    In order to meet the needs of efficient purification of products from natural resources, this paper developed an automatic vacuum liquid chromatographic device (AUTO-VLC) and applied it to the component separation of petroleum ether extracts of Schisandra chinensis (Turcz) Baill. The device was comprised of a solvent system, a 10-position distribution valve, a 3-position changes valve, dynamic axis compress chromatographic columns with three diameters, and a 10-position fraction valve. The programmable logic controller (PLC) S7- 200 was adopted to realize the automatic control and monitoring of the mobile phase changing, column selection, separation time setting and fraction collection. The separation results showed that six fractions (S1-S6) of different chemical components from 100 g Schisandra chinensis (Turcz) Baill. petroleum ether phase were obtained by the AUTO-VLC with 150 mm diameter dynamic axis compress chromatographic column. A new method used for the VLC separation parameters screened by using multiple development TLC was developed and confirmed. The initial mobile phase of AUTO-VLC was selected by taking Rf of all the target compounds ranging from 0 to 0.45 for fist development on the TLC; gradient elution ratio was selected according to k value (the slope of the linear function of Rf value and development times on the TLC) and the resolution of target compounds; elution times (n) were calculated by the formula n ≈ ΔRf/k. A total of four compounds with the purity more than 85% and 13 other components were separated from S5 under the selected conditions for only 17 h. Therefore, the development of the automatic VLC and its method are significant to the automatic and systematic separation of traditional Chinese medicines.

  18. Express analysis of explosives, chemical warfare agents and drugs with multicapillary column gas chromatography and ion mobility increment spectrometry. (United States)

    Buryakov, Igor A


    Description of a gas chromatograph designed for express analysis of explosives (2,4-dinitrotoluene, 2,4,6-trinitrotoluene, pentaerythritol tetranitrate), chemical warfare agents (mustard gas, lewisite, sarin) and drugs (heroin, cocaine hydrochloride, crack) is given. The devices comprises a multicapillary chromatographic column and an ion mobility increment spectrometer (MCC-IMIS). The main analytical characteristics of an IMIS (estimated detection limit (DL), linear dynamic range (LDR), speed of response) and a chromatographic column (separation power, degree of separation, a number of possible peaks at a chromatogram section, divided by analysis time) are determined. The maximum value of DL equal to 5 pg/ml was registered for cis-alpha-LW, and the lowest one of 0.001 pg/ml was for cocaine. The maximum value of LDR equal to 1000 was registered for sarin and the lowest one of 150 was for the ions of lewisite. Speed of response of one compound detection with the IMIS was 0.7 s.

  19. Capillary electrophoresis and column chromatography in biomedical chiral amino acid analysis. (United States)

    Waldhier, Magdalena C; Gruber, Michael A; Dettmer, Katja; Oefner, Peter J


    Free amino acids are typically quantified as the sum of their enantiomers, because in terrestrial organisms they mainly exist in the left-handed form. However, with increasing understanding of the biological significance of right-handed amino acids interest in enantioselective quantification of amino acids has steadily increased. Initially, electrophoretic and chromatographic methods using chiral (pseudo)-stationary phases or chiral eluents were applied to the separation of amino acid enantiomers. Later, derivatization of amino acids prior to chromatography with chiral reagents gained in popularity, because the diastereomers formed can be resolved on conventional reversed-phase columns. Novel multi-interaction chiral columns turned attention back to direct chiral chromatographic methods. Hyphenation to mass spectrometry has increasingly replaced optical detection because of superior selectivity, although this has not obviated the need for baseline resolution of amino acid enantiomers. Despite the progress made, enantioselective separation and quantification of amino acids remains an analytical challenge owing to frequently incomplete resolution of all naturally occurring enantiomers and insufficient sensitivity for the determination of the trace amounts of D-amino acids typically found in biological fluids and tissues.

  20. A novel molecular distance edge vector as applied to chemical modeling of quantitative structure-retention relationships: Various gas chromatographic retention behaviors of polychlorinated dibenzo-furans on different polarity-varying stationary phases

    Institute of Scientific and Technical Information of China (English)

    DENG Hong; HUANG Ping; HU Yinyu; YE Nancy; LI Zhiliang


    Based on the identical group as a pseudo atom instead of a typical atom, a novel modified molecular distance-edge (MDE) vector μ was developed in our laboratory to characterize chemical structure of polychlorinated dibenzofurans (PCDFs) congeners and/or isomers. Quantitative structure-retention relationships (QSRRs) between the new VMDE parameters and gas chromatographic (GC) retention behavior of PCDFs were then generated by multiple linear regression (MLR) method for non-polar, moderately polar, and polar stationary phases. Four excellent models with high correlation coefficients, R=0.984-0.995, were proposed for non-polar columns (DB-5, SE-54, OV-101). For the moderately polar columns (OV-1701), the correlation coefficient of the developed good model is only 0.958. For the polar columns (SP-2300), the QSRR model is poor with R=0.884. Then cross validation with leave-one out of procedure (CV) is performed in high correlation with the non-polar (Rcv=992-0.974) and weakly polar (Rcv=921) columns and in little correlation (Rcv=0.834) with the polar columns. These results show that the new μ vector is suitable for describing the retention behaviors of PCDFs on non-polar and moderately polar stationary phases and not for the various gas chromatographic retention behaviors of PCDFs on the different polarity-varying stationary phases.

  1. Matrix-assisted refolding of autoprotease fusion proteins on an ion exchange column. (United States)

    Schmoeger, Elisabeth; Berger, Eva; Trefilov, Alexandru; Jungbauer, Alois; Hahn, Rainer


    Refolding of proteins must be performed under very dilute conditions to overcome the competing aggregation reaction, which has a high reaction order. Refolding on a chromatography column partially prevents formation of the intermediate form prone to aggregation. A chromatographic refolding procedure was developed using an autoprotease fusion protein with the mutant EDDIE from the N(pro) autoprotease of pestivirus. Upon refolding, self-cleavage generates a target peptide with an authentic N-terminus. The refolding process was developed using the basic 1.8-kDa peptide sSNEVi-C fused to the autoprotease EDDIE or the acidic peptide pep6His, applying cation and anion exchange chromatography, respectively. Dissolved inclusion bodies were loaded on cation exchange chromatographic resins (Capto S, POROS HS, Fractogel EMD SO(3)(-), UNOsphere S, SP Sepharose FF, CM Sepharose FF, S Ceramic HyperD F, Toyopearl SP-650, and Toyopearl MegaCap II SP-550EC). A conditioning step was introduced in order to reduce the urea concentration prior to the refolding step. Refolding was initiated by applying an elution buffer containing a high concentration of Tris-HCl plus common refolding additives. The actual refolding process occurred concurrently with the elution step and was completed in the collected fraction. With Capto S, POROS HS, and Fractogel SO(3)(-), refolding could be performed at column loadings of 50mg fusion protein/ml gel, resulting in a final eluate concentration of around 10-15 mg/ml, with refolding and cleavage step yields of around 75%. The overall yield of recovered peptide reached 50%. Similar yields were obtained using the anion exchange system and the pep6His fusion peptide. This chromatographic refolding process allows processing of fusion peptides at a concentration range 10- to 100-fold higher than that observed for common refolding systems.

  2. Determination of Trace Amount of Polycyclic Aromatic Hydrocarbons in Urban Sewage by Solid-phase Extraction Coupled with High Performance Liquid Chromatograph

    Institute of Scientific and Technical Information of China (English)


    [Method] This study aimed to determine trace amount of polycyclic aromatic hydrocarbons(PAHs) in urban sewage by using solid-phase extraction(SPE) coupled with high performance liquid chromatograph(HPLC).[Method] From the aspects of solid-phase extraction column,elution solvent,elution volume,elution speed and so forth,the test conditions of SPE-HPLC method were optimized,and trace amount of PAHs in urban sewage was determined.[Result] The optimized solid-phase extraction conditions were SUPELCLEAN LC-18 so...

  3. Rapid and sensitive electron-capture gas chromatographic method for the determination of pinazepam and its metabolites in human plasma, urine and milk. (United States)

    Pacifici, G M; Placidi, G F


    A rapid, sensitive and specific gas-liquid chromatographic method for the measurement of pinazepam and its metabolites in biological fluids is reported. After a single extraction of the sample with toluene, the organic phase is concentrated and, after chromatography on a 3% OV-17 column, measured with an electron-capture detector. The sensitivity was 1.0 ng/ml for pinazepam and 5.0 ng/ml for its metabolites. Plasma levels and urinary excretion in human volunteers and plasma and milk levels in women suffering from anxiety during breastfeeding are reported.

  4. Elastic stability of non-uniform columns (United States)

    Lee, S. Y.; Kuo, Y. H.


    A simple and efficient method is proposed to investigate the elastic stability of three different tapered columns subjected to uniformly distributed follower forces. The influences of the boundary conditions and taper ratio on critical buckling loads are investigated. The critical buckling loads of columns of rectangular cross section with constant depth and linearly varied width ( T1), constant width and linearly varied depth ( T2) and double taper ( T3) are investigated. Among the three different non-uniform columns considered, taper ratio has the greatest influence on the critical buckling load of column T3 and the lowest influence on that of column T1. The types of instability mechanisms for hinged-hinged and cantilever non-uniform columns are divergence and flutter respectively. However, for clamped-hinged and clamped-clamped non-uniform columns, the type of instability mechanism for column T1 is divergence, while that for columns T2 and T3 is divergence only when the taper ratio of the columns is greater than certain critical values and flutter for the rest value of taper ratio. When the type of instability mechanism changes from divergence to flutter, there is a finite jump for the critical buckling load. The influence of taper ratio on the elastic stability of cantilever column T3 is very sensitive for small values of the taper ratio and there also exist some discontinieties in the critical buckling loads of flutter instability. For a hinged-hinged non-uniform column ( T2 or T3) with a rotational spring at the left end of the column, when the taper ratio is less than the critical value the instability mechanism changes from divergence to flutter as the rotational spring constant is increased. For a clamped-elastically supported non-uniform column, when the taper ratio is greater than the critical value the instability mechanism changes from flutter to divergence as the translational spring constant is increased.

  5. Chromatographic characterisation, under highly aqueous conditions, of a molecularly imprinted polymer binding the herbicide 2,4-dichlorophenoxyacetic acid. (United States)

    Legido-Quigley, C; Oxelbark, J; De Lorenzi, E; Zurutuza-Elorza, A; Cormack, P A G


    The affinity of a 2,4-dichlorophenoxyacetic acid (2,4-D) molecularly imprinted polymer (MIP), which was synthesised directly in an aqueous organic solvent, for its template (2,4-D) was studied and compared with the affinity exhibited by two other reference (control) polymers, NIPA and NIPB, for the same analyte. Zonal chromatography was performed to establish the optimal selectivity, expressed as imprinting factor (IF), under chromatographic conditions more aqueous than those described so far in the literature. Frontal analysis (FA) was performed on columns packed with these polymers, using an optimized mobile phase composed of methanol/phosphate buffer (50/50, v/v), to extract adsorption isotherm data and retrieve binding parameters from the best isotherm model. Surprisingly, the template had comparable and strong affinity for both MIP (K = 3.8x10(4) M(-1)) and NIPA (K = 1.9x10(4) M(-1)), although there was a marked difference in the saturation capacities of selective and non-selective sites, as one would expect for an imprinted polymer. NIPB acts as a true control polymer in the sense that it has relatively low affinity for the template (K = 8.0x10(2) M(-1)). This work provides the first frontal chromatographic characterization of such a polymer in a water-rich environment over a wide concentration range. The significance of this work stems from the fact that the chromatographic approach used is generic and can be applied readily to other analytes, but also because there is an increasing demand for well-characterised imprinted materials that function effectively in aqueous media and are thus well-suited for analytical science applications involving, for example, biofluids and environmental water samples.

  6. Impact of reversed phase column pairs in comprehensive two-dimensional liquid chromatography. (United States)

    Allen, Robert C; Barnes, Brian B; Haidar Ahmad, Imad A; Filgueira, Marcelo R; Carr, Peter W


    A major issue in optimizing the resolving power of two-dimensional chromatographic separations is the choice of the two phases so as to maximize the distribution of the analytes over the separation space. In this work, we studied the choice of appropriate reversed phases to use in on-line comprehensive two-dimensional liquid chromatography (LC×LC). A set of four chemically different conventional bonded reversed phases was used in the first dimension. The second dimension column was either a conventional bonded C18 phase or a carbon-clad phase (CCP). The LC×LC chromatograms and contour plots were all rather similar indicating that the selectivities of the two phases were also similar regardless of the reverse phase column used in the first dimension. Further, the spatial coverage seen with all four first dimension stationary phases when paired with a second dimension C18 phase were low and the retention times were strongly correlated. However, when the C18 column was replaced with the CCP column much improved separations were observed with higher spatial coverages, greater orthogonalities and significant increases in the number of observed peaks.

  7. Development Of ABEC Column For Separation Of Tc-99 From Northstar Dissolved Target Solution

    Energy Technology Data Exchange (ETDEWEB)

    Stepinski, Dominique C. [Argonne National Lab. (ANL), Argonne, IL (United States); Bennett, Megan E. [Argonne National Lab. (ANL), Argonne, IL (United States); Naik, Seema R. [Argonne National Lab. (ANL), Argonne, IL (United States); ling, lei [Argonne National Lab. (ANL), Argonne, IL (United States); Wang, N-H. Linda [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)


    Batch and column breakthrough experiments were performed to determine isotherms and mass-transfer parameters for adsorption of Tc on aqueous biphasic extraction chromatographic (ABEC) sorbent in two solutions: 200 g/L Mo, 5.1 M K+, 1 M OH-, and 0.1 M NO3- (Solution A) and 200 g/L Mo, 9.3 M K+, 5 M OH-, and 0.1 M NO3- (Solution B). Good agreement was found between the isotherm values obtained by batch and column breakthrough studies for both Solutions A and B. Potassium-pertechnetate intra-particle diffusivity on ABEC resin was estimated by VERSE simulations, and good agreement was found among a series of column-breakthrough experiments at varying flow velocities, column sizes, and technetium concentrations. However, testing of 10 cc cartridges provided by NorthStar with Solutions A and B did not give satisfactory results, as significant Tc breakthrough was observed and ABEC cartridge performance varied widely among experiments. These different experimental results are believed to be due to inconsistent preparation of the ABEC resin prior to packing and/or inconsistent packing.

  8. Development and Validation of Liquid Chromatographic Method for Estimation of Naringin in Nanoformulation. (United States)

    Musmade, Kranti P; Trilok, M; Dengale, Swapnil J; Bhat, Krishnamurthy; Reddy, M S; Musmade, Prashant B; Udupa, N


    A simple, precise, accurate, rapid, and sensitive reverse phase high performance liquid chromatography (RP-HPLC) method with UV detection has been developed and validated for quantification of naringin (NAR) in novel pharmaceutical formulation. NAR is a polyphenolic flavonoid present in most of the citrus plants having variety of pharmacological activities. Method optimization was carried out by considering the various parameters such as effect of pH and column. The analyte was separated by employing a C18 (250.0 × 4.6 mm, 5 μm) column at ambient temperature in isocratic conditions using phosphate buffer pH 3.5: acetonitrile (75 : 25% v/v) as mobile phase pumped at a flow rate of 1.0 mL/min. UV detection was carried out at 282 nm. The developed method was validated according to ICH guidelines Q2(R1). The method was found to be precise and accurate on statistical evaluation with a linearity range of 0.1 to 20.0 μg/mL for NAR. The intra- and interday precision studies showed good reproducibility with coefficients of variation (CV) less than 1.0%. The mean recovery of NAR was found to be 99.33 ± 0.16%. The proposed method was found to be highly accurate, sensitive, and robust. The proposed liquid chromatographic method was successfully employed for the routine analysis of said compound in developed novel nanopharmaceuticals. The presence of excipients did not show any interference on the determination of NAR, indicating method specificity.

  9. Development and Validation of Liquid Chromatographic Method for Estimation of Naringin in Nanoformulation

    Directory of Open Access Journals (Sweden)

    Kranti P. Musmade


    Full Text Available A simple, precise, accurate, rapid, and sensitive reverse phase high performance liquid chromatography (RP-HPLC method with UV detection has been developed and validated for quantification of naringin (NAR in novel pharmaceutical formulation. NAR is a polyphenolic flavonoid present in most of the citrus plants having variety of pharmacological activities. Method optimization was carried out by considering the various parameters such as effect of pH and column. The analyte was separated by employing a C18 (250.0 × 4.6 mm, 5 μm column at ambient temperature in isocratic conditions using phosphate buffer pH 3.5: acetonitrile (75 : 25% v/v as mobile phase pumped at a flow rate of 1.0 mL/min. UV detection was carried out at 282 nm. The developed method was validated according to ICH guidelines Q2(R1. The method was found to be precise and accurate on statistical evaluation with a linearity range of 0.1 to 20.0 μg/mL for NAR. The intra- and interday precision studies showed good reproducibility with coefficients of variation (CV less than 1.0%. The mean recovery of NAR was found to be 99.33 ± 0.16%. The proposed method was found to be highly accurate, sensitive, and robust. The proposed liquid chromatographic method was successfully employed for the routine analysis of said compound in developed novel nanopharmaceuticals. The presence of excipients did not show any interference on the determination of NAR, indicating method specificity.

  10. Review of UV spectroscopic, chromatographic, and electrophoretic methods for the cholinesterase reactivating antidote pralidoxime (2-PAM). (United States)

    John, Harald; Blum, Marc-Michael


    Pralidoxime (2-PAM) belongs to the class of monopyridinium oximes with reactivating potency on cholinesterases inhibited by phosphylating organophosphorus compounds (OPC), for example, pesticides and nerve agents. 2-PAM represents an established antidote for the therapy of anticholinesterase poisoning since the late 1950s. Quite high therapeutic concentrations in human plasma (about 13 µg/ml) lead to concentrations in urine being about 100 times higher allowing the use of less sensitive analytical techniques that were used especially in the early years after 2-PAM was introduced. In this time (mid-1950s until the end of the 1970s) 2-PAM was most often analyzed by either paper chromatography or simple UV spectroscopic techniques omitting any sample separation step. These methods were displaced completely after the establishment of column liquid chromatography in the early 1980s. Since then, diverse techniques including cation exchange, size-exclusion, reversed-phase, and ligand-exchange chromatography have been introduced. Today, the most popular method for 2-PAM quantification is ion pair chromatography often combined with UV detection representing more than 50% of all column chromatographic procedures published. Furthermore, electrophoretic approaches by paper and capillary zone electrophoresis have been successfully used but are seldom applied. This review provides a commentary and exhaustive summary of analytical techniques applied to detect 2-PAM in pharmaceutical formulations and biological samples to characterize stability and pharmacokinetics as well as decomposition and biotransformation products. Separation techniques as well as diverse detectors are discussed in appropriate detail allowing comparison of individual preferences and limitations. In addition, novel data on mass spectrometric fragmentation of 2-PAM are provided.

  11. A versatile noninvasive method for adsorber quantification in batch and column chromatography based on the ionic capacity. (United States)

    Huuk, Thiemo C; Briskot, Till; Hahn, Tobias; Hubbuch, Jürgen


    Within the Quality by Design (QbD) framework proposed by the International Conference on Harmonisation (ICH), high-throughput process development (HTPD) and mechanistic modeling are of outstanding importance for future biopharmaceutical chromatography process development. In order to compare the data derived from different column scales or batch chromatographies, the amount of adsorber has to be quantified with the same noninvasive method. Similarly, an important requirement for the implementation of mechanistic modeling is the reliable determination of column characteristics such as the ionic capacity Λ for ion-exchange chromatography with the same method at all scales and formats. We developed a method to determine the ionic capacity in column and batch chromatography, based on the adsorption/desorption of the natural, uv-detectable amino acid histidine. In column chromatography, this method produces results comparable to those of classical acid-base titration. In contrast to acid-base titration, this method can be adapted to robotic batch chromatographic experiments. We are able to convert the adsorber volumes in batch chromatography to the equivalent volume of a compressed column. In a case study, we demonstrate that this method increases the quality of SMA parameters fitted to batch adsorption isotherms, and the capability to predict column breakthrough experiments. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:666-677, 2016.

  12. Development and validation of a rapid ultra high pressure liquid chromatographic method for the determination of methylxanthines in herbal infusions. (United States)

    Zacharis, Constantinos K; Kika, Fotini S; Tzanavaras, Paraskevas D; Fytianos, Konstantinos


    An ultra high pressure liquid chromatographic method coupled with diode array detector (UHPLC-DAD) has been developed and validated for the fast separation and determination of three major methylxanthines, i.e., caffeine, theophylline and theobromine, in various herbal beverages. Isocratic elution using 0.1vol% formic acid/CH3OH (92.5:7.5, v/v) enabled the completion of the separation cycle in less than 3min using a flow rate of 0.7mL/min and a column temperature of 50°C. Validation of the method included linearity (0.5-50mg/L), limits of detection (12-35μg/L) and quantification (40-120μg/L), precision, matrix effect and accuracy. The percent recoveries ranged between 90 and 108%.

  13. Development of liquid chromatographic enantiomer separation methods and validation for the estimation of (R)-enantiomer in eslicarbazepine acetate. (United States)

    Mone, Mahesh Kumar; Chandrasekhar, K B


    Chiral separation method development was carried out for eslicarbazepine acetate and its (R)-enantiomer on diverse chiral stationary phases. Better chiral selectivity was observed on cellulose tris-(3,5-dichlorophenylcarbamate) immobilized column (Chiralpak IC-3). Under polar organic mode (POM), with 100% acetonitrile as mobile phase and 0.5 ml/min flow, a resolution close to three was achieved. With normal phase (NP) mobile phase consisting dichloromethane:ethanol (90:10, v/v) and 1.0 ml/min flow, a resolution close to six was achieved. Detection was done by UV at 220 and 240 nm respectively. Both the methods were found to be robust and were validated with respect to robustness, precision, linearity, limit of detection, limit of quantification and accuracy. The proposed methods are suitable for the accurate estimation of (R)-enantiomer in bulk drug samples up to 0.1% when a 1mg/ml analyte test solution is chromatographed.

  14. Determination of chromatographic dissociation constants of some carbapenem group antibiotics and quantification of these compounds in human urine. (United States)

    Çubuk Demiralay, Ebru; Koç, Duygu; Daldal, Y Doğan; Alsancak, Güleren; Ozkan, Sibel A


    The dissociation constant values (s (s) pKa ) of some carbapenem group drugs (ertapenem, meropenem, doripenem) in different percentages of methanol-water binary mixtures (18, 20 and 22%, v/v) were determined from the mobile phase pH dependence of their retention factor. Evaluation of these data was performed using the NLREG program. From calculated pKa values, the aqueous pKa values of these subtances were calculated by different approaches. Moreover, the correlation established between retention factor and the pH of the water-methanol mobile phase was used to determine the optimum separation conditions. In order to validate the optimized conditions, these drugs were studied in human urine. The chromatographic separation was realized using a Gemini NX C18 column (250 × 4.6 mm i.d., 5 µm particles) and UV detector set at 220 and 295 nm.

  15. Development and validation of high-perfomance liquid chromatographic method for determination of ofloxacin and lomefloxacin in human plasma

    Directory of Open Access Journals (Sweden)



    Full Text Available Ahigh-performance liquid chromatographicmethod for the determination of ofloxacin and lomefloxacin in human plasma has been developed and validated. The effect of organic modifiers on the retention of the investigated drugs was investigated. Asimple isocratic chromatographic assay with UV-detection at 280 nm was performed on a Hibar Lichrospher 100 RP 8 column (250×4.6 mm, 5 mm. Merck, Germany using a mixture of acetonitrile and 0.5 % triethylamine in water (pH adjusted to 2.5 with H3PO4 (15:85, V/V as the mobile phase at flow rate of 1.2 mL min-1. The calibration curves were linear in the concentration ragne of 0.5 – 6.0 mg mL-1 for ofloxacin and 0.2-4.5 mg mL-1 for lomefloxacin.

  16. Development and validation of a liquid chromatographic-electrospray tandem mass spectrometric multiresidue method for anthelmintics in milk. (United States)

    De Ruyck, Hendrik; Daeseleire, Els; De Ridder, Herman; Van Renterghem, Roland


    A liquid chromatographic-tandem mass spectrometric multiresidue method for the simultaneous quantitative determination of the tetrahydroimidazole, levamisole and the benzimidazoles thiabendazole, oxfendazole, oxibendazole, albendazole, fenbendazole, febantel and triclabendazole in milk has been developed and validated. The anthelmintic residues were extracted with ethyl acetate. The liquid chromatographic separation was performed on a reversed-phase C18 column with gradient elution. The analytes were detected by tandem quadrupole mass spectrometry after positive electrospray ionisation by multiple reaction monitoring. The confirmatory method is very sensitive and each component can be detected at a residue level lower than 1 microgram/l. The method is validated according to the revised European Union requirements and all parameters were found conform the criteria. The evaluated parameters were linearity, specificity, stability, recovery, precision (repeatability and within-laboratory reproducibility) and analytical limits (detection limit, decision limit and detection capability). This analytical method is applied in the Belgian monitoring programme for classical anthelmintic veterinary drugs in raw farm cow's milk.

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

    Savasci, Sahin; Akçay, Mehmet; Ergül, Soner


    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.


    Directory of Open Access Journals (Sweden)

    Lanka Venkateswararao


    Full Text Available A novel reverse phase high performance liquid chromatographic method (RP-HPLC was developed and validated for the determination of doxofylline (DXF in pharmaceutical formulations. Agilent 1100 series HPLC instrument equipped with variable wavelength programmable UV-Visible detector and a chromosil C18 (250mm x 4.6mm, 5μm column with an auto injector was used for the present investigation. A volume of 20µL of working standard of concentration 25µg/mL was injected into the chromatographic system, the component was separated by using the mobile phase of the mixture of potassium dihydrogen phosphate buffer of pH 5.5 and acetonitrile in the ratio 75:25(v/v at a flow rate of 1.0 mL/min and the detection of the components was carried out at a wavelength of 275nm. Chemstation software was used for the data acquisition through out the analysis. The system suitable parameters such as number of theoretical plates, tailing factor and resolution were found to be satisfactory. The retention time of the component was found to be at 4.814 minutes. The proposed method was validated in terms of precision, accuracy, linearity, limit of detection, limit of quantification, robustness and ruggedness. The developed method was found to be rapid, simple and sensitive hence it could be used as an alternative method in assay of the doxofylline in any pharmaceutical industries.

  19. Chromatographic analysis of some drugs employed in erectile dysfunction therapy: qualitative and quantitative studies using calixarene stationary phase. (United States)

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


    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.

  20. Development of a validated liquid chromatographic method for determination of related substances of telmisartan in bulk drugs and formulations. (United States)

    Rao, R Nageswara; Guru Prasad, K; Gangu Naidu, Ch; Maurya, Pawan K


    A simple and rapid reversed phase liquid chromatographic method for separation and determination of the related substances of telmisartan (TLM) was developed and validated. The chromatographic separation was achieved on Lichrospher RP-18 column (250 × 4.6 mm, 5 μm), using 20 mM ammonium acetate containing 0.1% (v/v) triethylamine (pH adjusted to 3.0 with trifluoroacetic acid) and acetonitrile as mobile phase at 25°C. The detection was performed at 254 nm. The method was validated and found to be robust, precise, specific and linear between 0.37 and 500 μg/mL. The limits of detection and quantification of telmisartan were 0.11 and 0.37 μg/mL, respectively. The method was successfully applied to quantify related substances and assay of TLM in bulk drugs and commercial tablets. The related substances relate to a novel synthetic route and different from those A-H impurities reported by European Pharmacopeia.

  1. Development and Validation of a Stability-Indicating Liquid Chromatographic Method for Estimating Olmesartan Medoxomil Using Quality by Design. (United States)

    Beg, Sarwar; Sharma, Gajanand; Katare, O P; Lohan, Shikha; Singh, Bhupinder


    The current studies entail systematic quality by design (QbD)-based development of a simple, rapid, sensitive and cost-effective stability-indicating method for the estimation of olmesartan medoxomil. Quality target method profile was defined and critical analytical attributes (CAAs) for the reverse-phase liquid chromatography method earmarked. Chromatographic separation accomplished on a C18 column using acetonitrile and water (containing 0.1% orthophosphoric acid, pH 3.5) in 40 : 60 (v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 243 nm. Risk assessment studies and screening studies facilitated comprehensive understanding of the factors affecting CAAs. The mobile phase ratio and flow rate were identified as critical method parameters (CMPs) and were systematically optimized using face-centered cubic design, evaluating for CAAs, namely peak area, retention time, theoretical plates and peak tailing. Statistical modelization was accomplished followed by response surface analysis for comprehending plausible interaction(s) among CMPs. Search for optimum solution was conducted through numerical and graphical optimization for demarcating the design space. Analytical method validation and subsequent forced degradation studies corroborated the method to be highly efficient for routine analysis of drug and its degradation products. The studies successfully demonstrate the utility of QbD approach for developing the highly sensitive liquid chromatographic method with enhanced method performance.

  2. 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


    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.

  3. Chromatographic fingerprinting analysis of Zhizhu Wan preparation by high-performance liquid chromatography coupled with photodiode array detector (United States)

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


    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

  4. Micellar high performance liquid chromatographic determination of flunixin meglumine in bulk, pharmaceutical dosage forms, bovine liver and kidney

    Directory of Open Access Journals (Sweden)

    Fathalla F. Belal


    Full Text Available A simple, sensitive and rapid liquid chromatographic method was developed and validated for the analysis of flunixin meglumine (flunixin-M in bulk, pharmaceutical dosage forms, bovine liver and kidney. Analytical separation was performed in less than 4 min using a C18 column with UV detection at 284 nm. A micellar solution composed of 0.15 M sodium dodecyl sulphate, 8% n-butanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 7.0 was used as the mobile phase. The method was fully validated in accordance with the International Conference on Harmonization (ICH guidelines. The limit of detection and the limit of quantitation were 0.02 and 0.06 μg mL−1, respectively. The recoveries obtained were in range of 95.58–106.94% for bovine liver and kidney. High extraction efficiency was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. The method showed good repeatability, linearity and sensitivity according to the evaluation of the validation parameters.

  5. Produced fluids separation using a coalascer column

    Energy Technology Data Exchange (ETDEWEB)

    Renouf, G.; Soveran, D.; Soveran, L. [Saskatchewan Research Council, Saskatoon, SK (Canada)


    This paper reports the results of a laboratory study in which a coalescer column was used to successfully remove water from produced heavy oil emulsions. The coalescer column is a simple, inexpensive, and environmentally friendly technology that can improve basic sediment and water values after 4 hours of settling time by about 38 per cent. The laboratory study tested the use of the column, and the effects of column length, column packing size, temperature, flow rate, demulsifier concentration, and water addition. More than 100 tests were conducted and 24 pairs of tests compared the treating effects with and without the column. The use of the coalescer column in the treatment facility resulted in a a reduction of demulsifier concentration from 250 ppm to 70 ppm, translating to an annual cost savings of $320,000 to $1,100,000 per battery. Incorporating the coalescer column also allowed operators to reduce both temperatures and demulsifier concentrations. The column also promoted faster treating. Water droplets grew by as much as 34 per cent, suggesting that treating time could be faster by 21 to 80 per cent. It was concluded that the coalescer column was very successful at improving water removal from heavy oil battery emulsions. 22 refs., 9 tabs., 7 figs.

  6. Column flotation testing at Suncor Energy Inc.

    Energy Technology Data Exchange (ETDEWEB)

    Cleyle, P.; Lee, L. [Suncor Energy Inc. Oil Sands, Fort McMurray, AB (Canada)


    The operations at Suncor's primary extraction plant were reviewed with reference to the column flotation process and the history of column flotation testing at Suncor. Tertiary bitumen recovery processes were also reviewed. In March and August 2005, an in-plant pilot scale column flotation test was conducted at Suncor's Millennium Primary Extraction plant near Fort McMurray, Alberta. The purpose was to evaluate the feasibility of using column flotation for tertiary bitumen recovery from cyclone overflow. The test was performed in a 4 ft diameter by 25 ft high column to determine the effects of column feed flow rate, froth wash water supply, and froth depth. The feed ranged from 0.14 to 3.79 wt per cent bitumen. Feed flow rate ranged from 59 to 237 USGPM. The test results indicated that wash water reduced froth mineral content. Increasing the wash water did not make any difference in mineral rejection. Although bitumen upgrading improved when the test column was operated at a deeper froth depth, the mineral content was not reduced. Both mechanical cell and flotation column tailings samples were collected in the flotation column tests. The average tailings composition for the last cell in the tertiary mechanical bank was 0.22 per cent bitumen, 12.10 per cent mineral, and 87.66 per cent water. At an average test column feed rate of 158 USGPM, the average tailings composition was 0.23 per cent bitumen, 12.13 per cent mineral, and 87.62 per cent water. It was concluded that flotation columns are capable of producing a tailings product similar to that of the tertiary mechanical bank. Therefore, it is feasible to use flotation columns as an alternative to mechanical cells. In fact, since there are no rotating parts requiring off-line maintenance work, flotation columns may be a better alternative from a maintenance and operations perspective. tabs., figs.

  7. Oscillating water column structural model

    Energy Technology Data Exchange (ETDEWEB)

    Copeland, Guild [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jepsen, Richard Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by a BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.

  8. TLC chromatographic-densitometric assay of ibuprofen and its impurities. (United States)

    Starek, Małgorzata; Krzek, Jan


    A simple and sensitive thin-layer chromatographic (TLC)-densitometric method for the quantitative estimation of S(+)-2-[4-isobutylphenyl]propionic acid (ibuprofen) and its impurities in pharmaceutical preparations has been developed. The chromatographic separation was carried out on silica gel 60 F(254) TLC plates using toluene-ethyl acetate-glacial acetic acid (17:13: 1, v/v/v) as the mobile phase. Detection was carried out densitometrically with a UV detector. The developed method has detection and quantitation limits ranging from 0.13 μg per spot to 0.72 μg per spot. For individual constituents the recovery ranged from 96.8% to 99.0%. In addition, the stability of ibuprofen solutions was investigated, including the effect of pH, temperature, and incubation time. The method is rapid, simple, and suitable for routine quality-control analysis of pharmaceuticals containing ibuprofen.

  9. Chiral Ionic Liquids in Chromatographic Separation and Spectroscopic Discrimination (United States)

    Li, Min; Bwambok, David K.; Fakayode, Sayo O.; Warner, Isiah M.

    Chiral ionic liquids (CILs) are a subclass of ionic liquids (ILs) in which the cation, anion, or both may be chiral. The chirality can be central, axial, or planar. CILs possess a number of unique advantageous properties which are inherited from ionic liquids including negligible vapor pressure, wide liquidus temperature range, high thermal stability, and high tunability. Due to their dual functionalities as chiral selectors and chiral solvents simultaneously, CILs recently have been widely used both in enantiomeric chromatographic separation and in chiral spectroscopic discrimination. In this chapter, the various applications of CILs in chiral chromatographic separations such as GC, HPLC, CE, and MEKC are reviewed. The applications of CILs in enantiomeric spectroscopic discrimination using techniques such as NMR, fluorescence, and NIR are described. In addition, chiral recognition and separation mechanism using the CILs as chiral selectors or chiral solvents is also discussed.

  10. Development and validation of a chromatographic method for determining Clematichinenoside AR and related impurities

    Directory of Open Access Journals (Sweden)

    Zhou Yang


    Full Text Available Abstract Background Clematichinenoside AR is a promising lead compound for the treatment of rheumatoid arthritis. A systematic research for the related impurities in AR bulk samples is still lacking. For the safe use of this natural product in future clinical practice, the structure and content of each constituent, including the main ingredient as well as the impurities in AR bulk sample must be characterized in detail. Results A simple and stability indicating RP-HPLC method was developed and validated for determining the purity of clematichinenoside AR (AR, a natural product from the roots of Clematis manshurica Rupr. (Ranunculaceae with the potential of treating rheumatoid arthritis. Five impurities were characterized, and impurity 2 (Clematomandshurica saponin F is a new triterpenoid saponin isolated from this product. Optimum separation for clematichinenoside AR and five related impurities was carried out on an Agilent octadecylsilane bonded silica gel column (TC-C18, 4.6 mm ×150 mm, 5 μm using a gradient HPLC method. The validation results showed good sensitivity, specificity, linearity(r2>0.9992 precision(RSD Conclusion Five related impurities of clematichinenoside AR were characterized, including a new triterpenoid saponins firstly found in clematichinenoside AR bulk samples. In the simple chromatographic method for determining clematichinenoside AR and its related impurities in bulk samples, the correction factor was better for the quality control in the relative stable concentrations.

  11. Liquid Chromatographic Determination of Pioglitazone in Pharmaceuticals, Serum and Urine Samples

    Directory of Open Access Journals (Sweden)

    Shahnaz Perveen


    Full Text Available A rapid and reliable analytical method based on high-performance liquid chromatography (HPLC with UV detection (221nm has been developed for the determination of the anti-hyperglycemic agent Pioglitazone in pharmaceutical formulations and biological fluids (serum and urine after clean-up with solid-phase extraction. Chromatographic separation was achieved with a Chromolith® Performance RP-18e (100×4.6mm column using mobile phase composition of acetonitrile: mixed phosphate buffer (pH 2.5; 10mM (30:70, v/v with a flow rate of 2.0mL/min. The total run time was 2 min. under optimized conditions. The calibration curve was found to be linear in the range of 1-10 µg mL-1 with regression coefficient of 0.9996, and the lower limit of detection 72 ng/20µL injection. The method has been validated for the system suitability, linearity, precision and accuracy, limits of detection, specificity, stability and robustness. The %recovery of Pioglitazone in pharmaceutical formulations was found to be 104.7%. The assay has been applied successfully to the pharmaceutical Tablet samples and biological fluids (serum and urine of healthy volunteers.

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

    Directory of Open Access Journals (Sweden)

    Chandra Bala Sekaran


    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.

  13. Gas chromatographic method for the determination of hexaconazole residues in black tea

    Institute of Scientific and Technical Information of China (English)

    Chinnachamy KARTHIKA; Paul James SACHIN


    A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.

  14. Hydroxypyridyl Imines: Enhancing Chromatographic Separation and Stereochemical Analysis of Chiral Amines via Circular Dichroism. (United States)

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


    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.

  15. An improved liquid chromatographic method for the analysis of tylosin and its impurities. (United States)

    Ashenafi, Dunge; Hoogmartens, Jos; Adams, Erwin


    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.

  16. Micellar Liquid Chromatographic Determination of Carbaryl and 1-Naphthol in Water, Soil, and Vegetables

    Directory of Open Access Journals (Sweden)

    Mei-Liang Chin-Chen


    Full Text Available A liquid chromatographic procedure has been developed for the determination of carbaryl, a phenyl-N-methylcarbamate, and its main metabolite 1-naphthol, using a C18 column (250’mm’ × ’4.6’mm with a micellar mobile phase and fluorescence detection at maximum excitation/emission wavelengths of 225/333’nm, respectively. In the optimization step, surfactants sodium dodecyl sulphate (SDS, Brij-35 and N-cetylpyridinium chloride monohydrate, and organic solvents propanol, butanol, and pentanol were considered. The selected mobile phase was 0.15’M SDS-6% (v/v-pentanol-0.01’M NaH2PO4 buffered at pH 3. Validation studies, according to the ICH Tripartite Guideline, included linearity (r>0.999, limit of detection (5 and 18’ng mL-1, for carbaryl and 1-naphthol, resp., and limit of quantification (15 and 50’ng mL-1, for carbaryl and 1-naphthol, resp., with intra- and interday precisions below 1%, and robustness parameters below 3%. The results show that the procedure was adequate for the routine analysis of these two compounds in water, soil, and vegetables samples.

  17. Determination of vapor pressures for nonpolar and semipolar organic compounds from gas chromatographic retention data (United States)

    Hinckley, D.A.; Bidleman, T.F.; Foreman, W.T.; Tuschall, J.R.


    Vapor pressures for nonpolar and moderately polar organochlorine, pyrethroid, and organophosphate insecticides, phthalate esters, and organophosphate flame retardants were determined by capillary gas chromatography (GC). Organochlorines and polycyclic aromatic hydrocarbons with known liquid-phase vapor pressures (P??L) (standard compounds) were chromatographed along with two reference compounds n-C20 (elcosane) and p,p???-DDT on a 1.0-m-long poly(dimethylsiloxane) bonded-phase (BP-1) column to determine their vapor pressures by GC (P??GC). A plot of log P??L vs log P??GC for standard compounds was made to establish a correlation between measured and literature values, and this correlation was then used to compute P??L of test compounds from their measured P??GC. P??L of seven major components of technical chlordane, endosulfan and its metabolites, ??-hexachlorocyclohexane, mirex, and two components of technical toxaphene were determined by GC. This method provides vapor pressures within a factor of 2 of average literature values for nonpolar compounds, similar to reported interlaboratory precisions of vapor pressure determinations. GC tends to overestimate vapor pressures of moderately polar compounds. ?? 1990 American Chemical Society.

  18. Chromatographic evaluation and antimicrobial activity of Neem (Azadirachta indica A. Juss., Meliaceae leaves hydroalcoholic extracts

    Directory of Open Access Journals (Sweden)

    Priscila D. Alves


    Full Text Available Neem (Azadirachta indica is an Indian tree well known for its several pharmacological activities, including antimicrobial activity. More than 300 composites have already been isolated and azadirachtin (AZA is its main active component. In the present work, Neem leaves hydroalcoholic extracts were prepared by percolation in 96% ethanol different concentrations (50%, 60%, 70%, 80% and 90% (v/v. The presence of AZA was tested by TLC by eluting the extracts and a standard solution of AZA through a chromatographic plate developed with anisaldehyde/sulfuric acid solution followed by heating. By HPLC, extracts elution took place on a C18 column, water:acetonitrile (60:40 as mobile phase, 1.0 mL/min flow rate and detection at λ217 nm. The extracts did not display AZA spots or peaks, however, they were tested against Gram-positive and Gram-negative bacteria, yeasts and a mold fungus. The extracts were tested in different increasing concentrations, in order to detect a dose-dependent relationship of the activity. Despite the absence of AZA, the 70% and 80% (v/v ethanol extracts showed activity against Staphylococcus aureus. However, this activity was not dose-dependent according to Tukey's test (q0,05;3;7.

  19. An improved extraction chromatographic resin for the separation of uranium from acidic nitrate media

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, M.L.; Horwitz, E.P.; Sajdak, L.R.; Chiarizia, R. [Chemistry Division, Argonne National Laboratory, 60439 Argonne, IL (United States)


    The preparation and characterization of a new extraction chromatographic resin exhibiting extraordinarily strong retention of hexavalent uranyl ion over a wide range of nitric acid concentrations and very high selectivity for U(VI) over Fe(III) and numerous other cations is described. This new material (designated U/TEVA-2) comprises a novel liquid stationary phase consisting of an equimolar mixture of diamyl amylphosphonate (DA[AP]) and Cyanex 923{sup registered} (a commercially available trialkyl-phosphine oxide, TRPO) sorbed on silanized silica or Amberchrom CG-71. Cyanex 923 is shown to be preferable to a related TRPO, Cyanex 925{sup registered}, due to its lower viscosity and higher selectivity for U(VI) over Fe(III). The retention of uranyl nitrate by the U/TEVA-2 resin, as measured by the k' values (number of free column values to peak maximum) is >5000 from approximately 0.1 to 8 M HNO{sub 3}. The ability of the new resin to strongly and selectively retain U(VI) from such a wide range of acid concentrations, along with its favorable physical properties, make it a good candidate for application in the separation and preconcentration of U(VI) from complex environmental, biological, and nuclear waste samples for subsequent determination.

  20. An improved extraction chromatographic resin for the separation of uranium from acidic nitrate media. (United States)

    Dietz, M L; Horwitz, E P; Sajdak, L R; Chiarizia, R


    The preparation and characterization of a new extraction chromatographic resin exhibiting extraordinarily strong retention of hexavalent uranyl ion over a wide range of nitric acid concentrations and very high selectivity for U(VI) over Fe(III) and numerous other cations is described. This new material (designated U/TEVA-2) comprises a novel liquid stationary phase consisting of an equimolar mixture of diamyl amylphosphonate (DA[AP]) and Cyanex 923((R)) (a commercially available trialkyl-phosphine oxide, TRPO) sorbed on silanized silica or Amberchrom CG-71. Cyanex 923 is shown to be preferable to a related TRPO, Cyanex 925((R)), due to its lower viscosity and higher selectivity for U(VI) over Fe(III). The retention of uranyl nitrate by the U/TEVA-2 resin, as measured by the k' values (number of free column values to peak maximum) is >5000 from approximately 0.1 to 8 M HNO(3). The ability of the new resin to strongly and selectively retain U(VI) from such a wide range of acid concentrations, along with its favorable physical properties, make it a good candidate for application in the separation and preconcentration of U(VI) from complex environmental, biological, and nuclear waste samples for subsequent determination.

  1. Furosine as a pasta quality marker: evaluation by an innovative and fast chromatographic approach. (United States)

    Giannetti, Vanessa; Mariani, Maurizio Boccacci; Mannino, Paola


    A fast and simple high-performance liquid chromatography method suitable for determining furosine level in heat-treated food samples was developed. The analysis of furosine was performed by a novel mixed-mode column that provides multiple and simultaneous retention mechanisms including cation-exchange, anion-exchange, reversed-phase, or hydrophilic interaction. Each retention mechanism could be independently controlled by setting chromatographic conditions. Adequate retention and selectivity of polar charged furosine were achieved by adjusting mobile phase pH, buffer concentration, organic content, and ionic strength. The optimized method was successfully applied to determinate furosine in durum wheat semolina pasta samples. Furosine level in pasta may be used as a reliable marker of health and nutritional damage occurring during pasta manufacture. Indeed, a low content of furosine is generally related to high nutritional quality of food and application of mild heat treatments. A wide range of dry pasta samples, collected from both supermarkets (large-scale retail trade) and shops selling local products, were analyzed. Variable amounts of furosine, ranging from 107 to 506 mg/100 g of protein, were found in pasta samples. The proposed method allows to discriminate products submitted to different time-temperature conditions during the drying process. At the same time, it may be used to highlight potential label fraud.

  2. Gas chromatographic quantitative analysis of methanol in wine: operative conditions, optimization and calibration model choice. (United States)

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


    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.

  3. Simultaneous determination of a quaternary mixture of oxomemazine, sodium benzoate, guaifenesin and paracetamol by chromatographic methods

    Directory of Open Access Journals (Sweden)

    Nehal F. Farid


    Full Text Available The aim of the present work was to develop simple, accurate, sensitive and selective methods for the simultaneous determination of oxomemazine (Ox, sodium benzoate (SB, guaifenesin (Gu, andparacetamol (Par. Two methods were described and validated for the simultaneous determination of the four drugs in syrup and suppositories. The first method was a reversed phase HPLC and UVdetection at 220 nm. The assay was performed using C 18 column and an isocratic elution using acetonitrile – methanol – 35 mM KH2PO4 (20: 5: 75; by volume, pH was adjusted to 2.9 ± 0.1 as the mobile phase. The flow rate was 1.5 mL/min and separation was achieved in less than 15 min. The second method was a TLC- spectrodensitometric method, used to separate, identify and quantify the four drugs when present in combination. The drugs were applied on silica gel plates and development was made using methylene chloride- methanol- acetic acid- 33% ammonia (89: 8.4: 2: 0.6, by volume as a mobile phase. The bands of the four drugs were quantified by scanning spectrodensitometricaly at 270 nm. The suggested chromatographic methods were validated and applied successfully to the analysis of the syrup and suppositories.

  4. Preparation of Medium Cation Exchange Stationary Phase of Polymeric Matrix and Their Chromatographic Properties

    Institute of Scientific and Technical Information of China (English)

    CHEN,Gang; GONG,Bo-Lin; BAI,Quan; GENG,Xin-Du


    Based on the monodisperse poly(glycidyl methacrylate-co-ethylenedimethacrylate) beads (PGMA/EDMA) with macropore as a medium, a new hydrophilic medium cation exchange (MCX) stationary phase for HPLC was synthesized by a new chemically modified method. The stationary phase was evaluated with the property of ion exchange, separability, reproducibility, hydrophilicity, effect of salt concentration, salt types, column loading and pH on the separation and retention of proteins in detail. It was found that it follows ion exchange chromatographic (IEC)retention mechanism. The measured bioactivity recovery for lysozyme was (96±5)%. The dynamic protein loading capacity of the synthesized MCX packings was 21.8 mg/g. Five proteins were almost completely separated within 6.0 min at a flow rate of 4 mL/min using the synthesized MCX resin. The MCX resin was also used for the rapid separation and purification of lysozyme from egg white with only one step. The purity and specific bioactivity of the purified lysozyme was found more than 95% and 70345 U/mg, respectively.

  5. Liquid chromatographic determination of naringin and neohesperidin as a detector of grapefruit juice in orange juice. (United States)

    Rouseff, R L


    Naringin/neohesperidin ratios can be used to differentiate orange juice which may contain added grapefruit juice from orange juice which may include juices from other naringin-containing cultivars. The naringin/neohesperidin ratios in juice vary from 14 to 83 in grapefruit (C. grandis) and from 1.3 to 2.5 in sour orange (C. aurantium) cultivars; the ratio is always less than 1 for the K-Early tangelo. Concentrations of both naringin and neohesperidin can be determined in orange juice by using a single liquid chromatographic isocratic reverse-phase system with a C-18 column. The detection limit for both compounds is 1 ppm with a linear working range to 500 ppm. Concentration relative standard deviations range from 0.47 to 1.06% for naringin and from 0.4 to 1.27% for neohesperidin. Naringin and neohesperidin recoveries ranged from 93 to 102% at concentrations of 5 and 50 ppm. Naringin values from blind duplicate samples of orange/grapefruit juice blends could be duplicated to +/- 3%.

  6. Synthesis of a specific monolithic column with artificial recognition sites for L-glutamic acid via cryo-crosslinking of imprinted nanoparticles. (United States)

    Göktürk, Ilgım; Üzek, Recep; Uzun, Lokman; Denizli, Adil


    In this study, a new molecular imprinting (MIP)-based monolithic cryogel column was prepared using chemically crosslinked molecularly imprinted nanoparticles, to achieve a simplified chromatographic separation (SPE) for a model compound, L-glutamic acid (L-Glu). Cryogelation through crosslinking of imprinted nanoparticles forms stable monolithic cryogel columns. This technique reduces the leakage of nanoparticles and increases the surface area, while protecting the structural features of the cryogel for stable and efficient recognition of the template molecule. A non-imprinted monolithic cryogel column (NIP) was also prepared, using non-imprinted nanoparticles produced without the addition of L-Glu during polymerization. The molecularly imprinted monolithic cryogel column (MIP) indicates apparent recognition selectivity and a good adsorption capacity compared to the NIP. Also, we have achieved a significant increase in the adsorption capacity, using the advantage of high surface area of the nanoparticles.

  7. Monitoring of benzodiazepines (clobazam, diazepam and their main active metabolites) in human plasma by column-switching high-performance liquid chromatography. (United States)

    Lacroix, C; Wojciechowski, F; Danger, P


    A column-switching high-performance liquid chromatographic method for the simultaneous determination of clobazam, diazepam and their main metabolites in human plasma is described. A 200-microliters plasma sample was directly injected into a precolumn filled with TSK-gel PW. After a washing step with potassium phosphate buffer, the retained substances were backflushed into a reversed-phase column with a mobile phase of acetonitrile-phosphate buffer-diethylamine. Various drugs frequently co-administered with clobazam or diazepam do not interfere with the determination.

  8. Chromatographic and electrophoretic methods for nanodisc purification and analysis

    DEFF Research Database (Denmark)

    Justesen, Bo Højen; Günther-Pomorski, Thomas


    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....

  9. Size-exclusion chromatographic NMR under HR-MAS


    Lucena Alcalde, Guillermo; Anderson, Natalie; Day, Iain J.


    The addition of stationary phases or sample modifiers can be used to modify the separation achievable in the diffusion domain of diffusion NMR experiments or provide information on the nature of the analyte–sample modifier interaction. Unfortunately, the addition of insoluble chromatographic stationary phases can lead to line broadening and degradation in spectral resolution, largely because of differences in magnetic susceptibility between the sample and the stationary phase. High-resolution...

  10. Chromatographic design for the purification of recombinant human membrane COMT


    Santos, Fátima Raquel Milhano dos


    Several studies suggest that membrane form of catechol-O-methyltransferase OMT (MB-COMT) is the main responsible for O-methylation at physiologically low concentrations of catecholamines. Despite this, until now no studies have been allowed the total isolation of MB-COMT. Then, a sustainable chromatographic step should be developed in order to obtain significant quantities of active and pure enzyme for posterior application on biochemical, kinetic and structural studies. For the first time, w...

  11. 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.

  12. The jet flotation column control system

    Energy Technology Data Exchange (ETDEWEB)

    Xu Zhiqiang; Ming Shangzhi; Liu Lijian; Huangfu Jinghua; Huo Sen; Zhang Rongzeng [China Univ. of Mining and Technology, Beijing (China). Mineral Processing Dept.; Yang Hongjun [Hebi Coal Mine Administrative (China)


    Compared with the conventional mechanical flotation column, the jet flotation column has the advantages of high selectivity of separation, low investment and production cost, low floor space requirement, low dosage of reagent, easy control; it is more suitable to process fine particles. Recently, many new types of flotation columns have been developed with new methods. Mineral Processing Dept., China University of Mining and Technology (Beijing) designed an aerated, double-jet flotation column in the lab and the industrial trial will be put into operation. One of the significant characteristics of the new type of flotation column is high selectivity of separation, fast bubble mineralization speed. As it is sensitive to various factors, a control system for flotation column has been developed to stabilize the working condition, and this set of control system has been operated in the lab experiment.

  13. The current revolution in column technology: how it began, where is it going? (United States)

    Gritti, Fabrice; Guiochon, Georges


    This work revisits the exceptionally rapid evolution of the technology of chromatographic columns and the important progress in speed of analysis and resolution power that was achieved over the last ten years. Whereas columns packed with 10 and 5 μm fully porous particles dominated the field for nearly thirty years (1975-2000), it took barely six years to see the commercialization of monolithic silica rods (2000), their raise to fame and decay to oblivion, the development of finer fully porous particles with size down to 1.7 μm (2006), and of sub-3 μm superficially porous particles (2006). Analysis times and plate heights delivered by columns packed with these recent packing materials have then been improved by more than one order of magnitude in this short period of time. This progress has rendered practically obsolete the age-old design of LC instruments. For low molecular weight compounds, analysts can now achieve peak capacities of 40 peaks in about 15s with a hold-up time of the order of 1.5s , in gradient elution, by operating columns packed with sub-3 μm shell particles at elevated temperatures, provided that they use optimized high pressure liquid chromatographs. This is the ultimate limit allowed by modern instruments, which have an extra-column band broadening contribution of 7 μL² at 4.0 mL/min and data acquisition rate of 160 Hz. The best 2.1 mm × 50 mm narrow-bore columns packed with 1.7 μm silica core-shell particles provide peaks that have a variance of 2.1 μL² for k=1. Finally, this work discusses possible ways to accelerate separations and, in the same time perform these separations at the same level of efficiency as they have today. It seems possible to pack columns with smaller particles, probably down to 1 μm and operate them with current vHPLC equipments for separations of biochemicals. Analyses of low molecular weight compounds will require new micro-HPLC systems able to operate 1mm I.D. columns at pressures up to 5 kbar, which

  14. Automated hydrophobic interaction chromatography column selection for use in protein purification. (United States)

    Murphy, Patrick J M; Stone, Orrin J; Anderson, Michelle E


    In contrast to other chromatographic methods for purifying proteins (e.g. gel filtration, affinity, and ion exchange), hydrophobic interaction chromatography (HIC) commonly requires experimental determination (referred to as screening or "scouting") in order to select the most suitable chromatographic medium for purifying a given protein (1). The method presented here describes an automated approach to scouting for an optimal HIC media to be used in protein purification. HIC separates proteins and other biomolecules from a crude lysate based on differences in hydrophobicity. Similar to affinity chromatography (AC) and ion exchange chromatography (IEX), HIC is capable of concentrating the protein of interest as it progresses through the chromatographic process. Proteins best suited for purification by HIC include those with hydrophobic surface regions and able to withstand exposure to salt concentrations in excess of 2 M ammonium sulfate ((NH(4;))(2;)SO(4;)). HIC is often chosen as a purification method for proteins lacking an affinity tag, and thus unsuitable for AC, and when IEX fails to provide adequate purification. Hydrophobic moieties on the protein surface temporarily bind to a nonpolar ligand coupled to an inert, immobile matrix. The interaction between protein and ligand are highly dependent on the salt concentration of the buffer flowing through the chromatography column, with high ionic concentrations strengthening the protein-ligand interaction and making the protein immobile (i.e. bound inside the column) (2). As salt concentrations decrease, the protein-ligand interaction dissipates, the protein again becomes mobile and elutes from the column. Several HIC media are commercially available in pre-packed columns, each containing one of several hydrophobic ligands (e.g. S-butyl, butyl, octyl, and phenyl) cross-linked at varying densities to agarose beads of a specific diameter (3). Automated column scouting allows for an efficient approach for determining

  15. SNAP-TITE Composite Column Reinforcement


    ECT Team, Purdue


    Recent earthquakes throughout the world have demonstrated the vulnerabilities of older reinforced concrete columns to seismic deformation demands. The Snap Tite Composite Column Reinforcement strengthens a concrete column by confining it in an external composite jacket, which prevents the concrete from expanding during seismic activity or prolonged freeze-thaw cycles. The pre-manufactured fiberglass jacket is comprised of glass fibers and corrosion resistant isopolyester resins.

  16. Parametric resonance in concrete beam-columns


    Sharma,Mamta R.; Singh,Arbind K; Benipal,Gurmail S


    A dynamic instability, called parametric resonance, is exhibited by undampedelastic beam-columns when under the action of pulsating axial force. The scope of the existing theory of parametric resonance is restricted to physically linear beam-columns undergoing finite lateral displacements. In this Paper, the dynamic behaviour of physically nonlinear elastic cracked concrete beam-columns under pulsating axial force and constant lateral force is investigated. The constitutive equations derived ...

  17. Water quality monitoring system for determination of ionic nutrients by ion-exclusion chromatography with spectrophotometric detection on cation- and anion-exchange resin columns using water eluent. (United States)

    Kozaki, Daisuke; Nakatani, Nobutake; Mori, Masanobu; Nakagoshi, Nobukazu; Tanaka, Kazuhiko


    A unified ion-exclusion chromatography (IEC) system for monitoring anionic and cationic nutrients like NH4+, NO2-, NO3-, phosphate ion, silicate ion and HCO3- was developed and applied to several environmental waters. The IEC system consisted of four IEC methodologies, including the IEC with ultraviolet (UV) form connected with detection at 210 nm for determining NH4+ on anion-exchange separation column in OH anion-exchange UV-conversion column in I- form in tandem, the IEC with UV-detection at 210 nm for determining simultaneously NO3- and NO3- on cation-exchange separation column in H+ form, the IEC with UV-detection at 210 nm for determining HCO3- on cation-exchange separation column in H+ form connected with anion-exchange UV-conversion column in I- form in tandem, and the IEC with visible-detection based on molybdenum-blue reaction for determining simultaneously silicate and phosphate ions on cation-exchange separation column in H+ form. These IEC systems were combined through three manually-driven 6-port column selection valves to select each separation column to determine selectively the ionic nutrients. Using this sequential water quality monitoring system, the analytical performances such as calibration linearity, reproducibility, detection limit and recovery were also tested under the optimized chromatographic conditions. This novel water quality monitoring system has been applied successfully for the determination of the ionic eutrophication components in sub-urban river waters.

  18. Detection of endogenous ethanol and other compounds in the breath by gas chromatography with on-column concentration of sample. (United States)

    Phillips, M; Greenberg, J


    A new method is described for collecting and concentrating volatile compounds in the breath, in order to facilitate their assay by gas chromatography. Breath was collected into sealed Mylar bags containing an internal standard (isopropyl alcohol). The sample was pumped through a cooled gas chromatograph column, where the volatile compounds were concentrated by adsorption onto the resin packing (Porapak Q) at 35 degrees C. The column was then heated, and the volatilized sample was separated for assay by flame ionization detection. The assay was highly sensitive for ethanol (detecting at least 4.0 nmol) and linear up to 20 nmol (r2 = 0.98). Accuracy and precision were determined by assaying nine replicates of a sample containing 12.0 nmol ethanol; a mean value of 12.18 nmol ethanol was obtained with a coefficient of variation of 10.26%. In a group of normal volunteers, endogenous breath ethanol concentrations ranged from 2.23 to 6.51 nmol/liter. This assay provided a number of advantages over previously described methods: The use of breath collection bags enabled the collection of samples outside the laboratory. The use of an internal standard in the collection bag reduced errors that might have resulted from leakage of the specimen. An on-column concentration of the sample in the gas chromatograph eliminated the need for an additional preconcentration device, such as a cryogenic or adsorptive trapping apparatus.

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

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


    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.

  20. 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. (United States)

    Moskovets, Eugene V; Ivanov, Alexander R


    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).

  1. Development and Validation of High Performance Liquid Chromatographic Method for the Simultaneous Determination of Ceftazidime and Sulbactam in Spiked Plasma and Combined Dosage form-Zydotam

    Directory of Open Access Journals (Sweden)

    Masoom R. Siddiqui


    Full Text Available Problem statement: To develop a sensitive method to determine simultaneously ceftizidime and sulbactam in spiked plasma and combined formulation. Approach: In this study an isocratic High performance liquid chromatographic method with UV detection at 230 nm was described for simultaneous determination of Ceftazidime and sulbactam sodium in plasma and combined dosage form. Chromatographic separation of two drugs was achieved on a Hypersil ODS C-18 column using a mobile phase consisting of a binary mixture of acetonitrile and tetrabutyl ammonium hydroxide adjusted to pH 5.0 with orthophosphoric acid in ratio 25:75. Results: The developed performance liquid chromatographic method offers symmetric peak shape, good resolution and reasonable retention time for both drugs. Linearity, accuracy and precision were found to be acceptable over the concentration range of 125-625 ppm for Ceftazidime and 62.5-312.5 ppm for sulbactam sodium. Conclusion: The results showed that this method could be well used for the simultaneous estimation of Ceftazidime and Sulbactam in plasma and combined formulation.

  2. Column: Factors Affecting Data Decay

    Directory of Open Access Journals (Sweden)

    Kevin Fairbanks


    Full Text Available In nuclear physics, the phrase decay rate is used to denote the rate that atoms and other particles spontaneously decompose. Uranium-235 famously decays into a variety of daughter isotopes including Thorium and Neptunium, which themselves decay to others. Decay rates are widely observed and wildly different depending on many factors, both internal and external. U-235 has a half-life of 703,800,000 years, for example, while free neutrons have a half-life of 611 seconds and neutrons in an atomic nucleus are stable.We posit that data in computer systems also experiences some kind of statistical decay process and thus also has a discernible decay rate. Like atomic decay, data decay fluctuates wildly. But unlike atomic decay, data decay rates are the result of so many different interplaying processes that we currently do not understand them well enough to come up with quantifiable numbers. Nevertheless, we believe that it is useful to discuss some of the factors that impact the data decay rate, for these factors frequently determine whether useful data about a subject can be recovered by forensic investigation.(see PDF for full column

  3. Development and validation of a simple stability-indicating high performance liquid chromatographic method for the determination of miconazole nitrate in bulk and cream formulations. (United States)

    De Zan, María M; Cámara, María S; Robles, Juan C; Kergaravat, Silvina V; Goicoechea, Héctor C


    A simple and stability-indicating high performance liquid chromatographic method was developed and validated for the determination of miconazole nitrate in bulk and cream preparations. The extraction step for cream samples consisted in a warming, cooling and centrifugation procedure that assures the elimination of the lipophilic matrix component, in order to avoid further precipitation in the chromatographic system. Separation was achieved on a ZORBAX Eclipse XDB - C18 (4.6 mm x 150 mm, 5 microm particle size) column, using a mobile phase consisting of water, methanol and acetonitrile, in a flow and solvent gradient elution for 15 min. The column was maintained at 25 degrees C and 10 microL of solutions were injected. UV detection was performed at 232 nm, although employment of a diode array detector allowed selectivity confirmation by peak purity evaluation. The method was validated reaching satisfactory results for selectivity, precision and accuracy. Degradation products in naturally aged samples could be simultaneously evaluated, without interferences in the quantitative analysis.

  4. Development and validation of reversed phase high performance liquid chromatographic method for determination of moxonidine in the presence of its impurities. (United States)

    Milovanović, Svetlana; Otašević, Biljana; Zečević, Mira; Zivanović, Ljiljana; Protić, Ana


    A simple, rapid, isocratic reversed-phase high-performance liquid chromatographic method was developed and validated for the analysis of moxonidine and its impurities in tablet formulations. The chromatographic separation was achieved on a Symmetry shield C18 column (250 mm × 4.6 mm, 5 μm) by employing a mobile phase consisting of methanol-potassium phosphate buffer (0.05 M) mixture (15:85, v/v) (pH 3.5) at a flow rate of 1 ml min⁻¹; detection at 255 nm. Central composite design technique and response surface method were used to evaluate the effects of variations of selected factors (buffer pH value, column temperature, methanol content) in order to achieve the best isocratic separation within short analysis time (less than 10 min), as well as for robustness test considerations. The method fulfilled the validation criteria: specificity, linearity, accuracy, precision, limit of detection and limit of quantitation. The method was successfully applied for the analysis of commercial moxonidine tablets.

  5. Development and Validation of a RP-Ultra performance liquid chromatographic Method for Quantification of Topotecan Hydrochloride in Bulk and Injection Dosage Form. (United States)

    Saini, P K; Jain, C L; Singh, R M; Mathur, S C; Singh, G N


    A simple, very fast, precise and accurate reverse phase ultra performance liquid chromatographic method was developed for the determination and validation of topotecan hydrochloride in bulk and injection dosage form. A Waters BEH C18, 50×2.1 mm, 1.7 μm particle size column in gradient mode was used with mobile phase comprising of 0.1% v/v orthophosphoric acid in water and acetonitrile. The analytical column was thermostated at 50° and flow rate was set at 0.4 ml per min, with photo diode array detection at 260 nm. The retention time of topotecan was found 1.38 min. The method was validated in terms of linearity, accuracy, precision and specificity. The calibration curve was found linear between 20 to 60 μg/ml. The limit of detection and limit of quantification were found 0.2353 and 0.7131 μg/ml, respectively. Percentage recoveries were obtained in the range of 98.91% and 99.17%. The proposed method is precise, accurate, selective and reproducible. The ultra performance liquid chromatographic assay procedure, which proved superior because of its greater sensitivity and relatively shorter (4 min) run time, should be an important tool for speedy future analysis of topotecan hydrochloride in bulk and its injection dosage form.

  6. Validation and application of reversed phase high-performance liquid chromatographic method for quantification of pizotifen malate in pharmaceutical solid dosage formulations. (United States)

    Rahman, Shaikh Mukidur; Lutfulkabir, Abulkalam; Jahan, M D Arshad; Momen, A Z M Ruhul; Rouf, Abushara Shamsur


    The aim of this study was to develop and validate an isocratic reversed phase high-performance liquid chromatographic method for quantification of pizotifen malate in pharmaceutical solid dosage formulations. Good chromatographic separation of pizotifen malate was achieved by using an analytical column, C(18) ODS column. The system was operated at 40°C oven temperature using a mobile phase consisting of acetonitrile and acetate buffer pH 7.0 (60:40) at a flow rate of 2 ml/min. The method showed high sensitivity with good linearity (r(2)= 0.99997) over the tested concentration range of 0.0020-0.0300 mg/ml for pizotifen malate. Detection was carried out at 231 nm and retention time was 2.838 min. Placebo and blank studies were performed and no peak was observed at the retention time of pizotifen malate. The intermediate precision and accuracy results (mean ± RSD, n=3) were (99.11±0.21) % and (99.19±0.55) % respectively with tailing factor (1.26±0.19). The proposed method was validated in terms of selectivity, linearity, accuracy, precision, range, detection and quantitation limit, system suitability and solution stability.This method can be successfully employed for simultaneous quantitative analysis of pizotifen malate in pharmaceutical solid dosage formulations.

  7. FastTrack to supercritical fluid chromatographic purification: Implementation of a walk-up analytical supercritical fluid chromatography/mass spectrometry screening system in the medicinal chemistry laboratory. (United States)

    Aurigemma, Christine; Farrell, William


    Medicinal chemists often depend on analytical instrumentation for reaction monitoring and product confirmation at all stages of pharmaceutical discovery and development. To obtain pure compounds for biological assays, the removal of side products and final compounds through purification is often necessary. Prior to purification, chemists often utilize open-access analytical LC/MS instruments because mass confirmation is fast and reliable, and the chromatographic separation of most sample constituents is sufficient. Supercritical fluid chromatography (SFC) is often used as an orthogonal technique to HPLC or when isolation of the free base of a compound is desired. In laboratories where SFC is the predominant technique for analysis and purification of compounds, a reasonable approach for quickly determining suitable purification conditions is to screen the sample against different columns. This can be a bottleneck to the purification process. To commission SFC for open-access use, a walk-up analytical SFC/MS screening system was implemented in the medicinal chemistry laboratory. Each sample is automatically screened through six column/method conditions, and on-demand data processing occurs for the chromatographers after each screening method is complete. This paper highlights the "FastTrack" approach to expediting samples through purification.

  8. Synthesis of metronidazole-imprinted molecularly imprinted polymers by distillation precipitation polymerization and their use as a solid-phase adsorbent and chromatographic filler. (United States)

    Liu, Jiang; Zhang, Lu; Li Han Song, Le; Liu, Yuan; Tang, Hui; Li, Yingchun


    Metronidazole-imprinted polymers with superior recognition properties were prepared by a novel strategy called distillation-precipitation polymerization. The as-obtained polymers were characterized by Fourier-transform infrared spectroscopy, laser particle size determination and scanning electron microscopy, and their binding performances were evaluated in detail by static, kinetic and dynamic rebinding tests, and Scatchard analysis. The results showed that when the fraction of the monomers was 5 vol% in the whole reaction system, the prepared polymers afforded good morphology, monodispersity, and high adsorption capacity and excellent selectivity to the target molecule, metronidazole. The optimal binding performance is 12.41 mg/g for metronidazole just before leakage occurred and 38.51 mg/g at saturation in dynamic rebinding tests. Metronidazole-imprinted polymers were further applied as packing agents in solid-phase extraction and as chromatographic filler, both of which served for the detection of metronidazole in fish tissue. The results illustrated the recoveries of spiked samples ranged from 82.97 to 87.83% by using molecularly imprinted solid-phase extraction combined with a C18 commercial column and 93.7 to 101.2% by directly using the polymer-packed chromatographic column. The relative standard deviation of both methods was less than 6%.

  9. Wall modified photonic crystal fibre capillaries as porous layer open tubular columns for in-capillary micro-extraction and capillary chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Kazarian, Artaches A. [Australian Centre for Research on Separation Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia); W.M. Keck FT-ICR-MS Laboratory, Department of Chemistry, North Carolina State University, Raleigh, NC (United States); Sanz Rodriguez, Estrella; Deverell, Jeremy A. [Australian Centre for Research on Separation Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia); McCord, James; Muddiman, David C. [W.M. Keck FT-ICR-MS Laboratory, Department of Chemistry, North Carolina State University, Raleigh, NC (United States); Paull, Brett, E-mail: [Australian Centre for Research on Separation Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia); ARC Centre of Excellence for Electromaterials Science, School of Physical Sciences, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001 (Australia)


    Wall modified photonic crystal fibre capillary columns for in-capillary micro-extraction and liquid chromatographic separations is presented. Columns contained 126 internal parallel 4 μm channels, each containing a wall bonded porous monolithic type polystyrene-divinylbenzene layer in open tubular column format (PLOT). Modification longitudinal homogeneity was monitored using scanning contactless conductivity detection and scanning electron microscopy. The multichannel open tubular capillary column showed channel diameter and polymer layer consistency of 4.2 ± 0.1 μm and 0.26 ± 0.02 μm respectively, and modification of 100% of the parallel channels with the monolithic polymer. The modified multi-channel capillaries were applied to the in-capillary micro-extraction of water samples. 500 μL of water samples containing single μg L{sup −1} levels of polyaromatic hydrocarbons were extracted at a flow rate of 10 μL min{sup −1}, and eluted in 50 μL of acetonitrile for analysis using HPLC with fluorescence detection. HPLC LODs were 0.08, 0.02 and 0.05 μg L{sup −1} for acenaphthene, anthracene and pyrene, respectively, with extraction recoveries of between 77 and 103%. The modified capillaries were also investigated briefly for direct application to liquid chromatographic separations, with the retention and elution of a standard protein (cytochrome c) under isocratic conditions demonstrated, proving chromatographic potential of the new column format, with run-to-run retention time reproducibility of below 1%. - Highlights: • Novel PS-DVB modified photonic crystal fibres for in-capillary micro-extraction. • New method for micro-extraction of PAHs and HPLC-FL detection at sub-ppb levels. • Demonstration of PS-DVB modified photonic crystal fibres for capillary bioseparations.

  10. Wall modified photonic crystal fibre capillaries as porous layer open tubular columns for in-capillary micro-extraction and capillary chromatography. (United States)

    Kazarian, Artaches A; Sanz Rodriguez, Estrella; Deverell, Jeremy A; McCord, James; Muddiman, David C; Paull, Brett


    Wall modified photonic crystal fibre capillary columns for in-capillary micro-extraction and liquid chromatographic separations is presented. Columns contained 126 internal parallel 4 μm channels, each containing a wall bonded porous monolithic type polystyrene-divinylbenzene layer in open tubular column format (PLOT). Modification longitudinal homogeneity was monitored using scanning contactless conductivity detection and scanning electron microscopy. The multichannel open tubular capillary column showed channel diameter and polymer layer consistency of 4.2 ± 0.1 μm and 0.26 ± 0.02 μm respectively, and modification of 100% of the parallel channels with the monolithic polymer. The modified multi-channel capillaries were applied to the in-capillary micro-extraction of water samples. 500 μL of water samples containing single μg L(-1) levels of polyaromatic hydrocarbons were extracted at a flow rate of 10 μL min(-1), and eluted in 50 μL of acetonitrile for analysis using HPLC with fluorescence detection. HPLC LODs were 0.08, 0.02 and 0.05 μg L(-1) for acenaphthene, anthracene and pyrene, respectively, with extraction recoveries of between 77 and 103%. The modified capillaries were also investigated briefly for direct application to liquid chromatographic separations, with the retention and elution of a standard protein (cytochrome c) under isocratic conditions demonstrated, proving chromatographic potential of the new column format, with run-to-run retention time reproducibility of below 1%.

  11. Dynamic effects of diabatization in distillation columns

    DEFF Research Database (Denmark)

    Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens


    The dynamic effects of diabatization in distillation columns are investigated in simulation emphasizing the heat-integrated distillation column (HIDiC). A generic, dynamic, first-principle model has been formulated, which is flexible enough to describe various diabatic distillation configurations...

  12. Dynamic Effects of Diabatization in Distillation Columns

    DEFF Research Database (Denmark)

    Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens


    The dynamic eects of diabatization in distillation columns are investigated in simulation with primary focus on the heat-integrated distillation column (HIDiC). A generic, dynamic, rst-principle model has been formulated, which is exible to describe various diabatic distillation congurations. Dyn...

  13. Rasch models with exchangeable rows and columns

    DEFF Research Database (Denmark)

    Lauritzen, Steffen Lilholt

    The article studies distributions of doubly infinite binary matrices with exchangeable rows and columns which satify the further property that the probability of any $m \\times n$ submatrix is a function of the row- and column sums of that matrix. We show that any such distribution is a (unique...... of existence of measures with given marginals....

  14. Rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography using a monolithic column

    Institute of Scientific and Technical Information of China (English)

    Xu Huang; Hong Yu; Ying Jie Dong


    A method for rapid and simultaneous determination of imidazolium and pyridinium ionic liquid cations by ion-pair chromatography with ultraviolet detection was developed.Chromatographic separations were performed on a reversed-phase silica-based monolithic column using 1-heptanesulfonic acid sodium-acetonitrile as mobile phase.The effects of ion-pair reagent and acetonitrile concentration on retention of the cations were investigated.The retention times of the cations accord with carbon number rule.The method has been successfully applied to the determination of four ionic liquids synthesized by organic chemistry laboratory.

  15. 蓝萼香茶菜高效液相指纹图谱研究%Study on chromatographic fingerprint of Isodon japonica by HPLC

    Institute of Scientific and Technical Information of China (English)

    杨丽霞; 朱晓红; 刘必旺


    Objective:To study and establish the chromatographic fingerprint of Isodon japonica by RP-HPLC. Methods:The chromatographic conditions were as follows.A Diamonsil C18 column was used and the mobile phase was composed of methanol and water (70:30). The flow rate was 1.0 mL/min,the column temperature was 20 ℃ and the detection wave-length was set at 231 nm. Results:The chromatographic fingerprint of Isodon japonica was established. The similarity of 5 batches of Isodon japonica was not lower than 0.962 7. Conclusion:The quality of Isodon japonica can be controlled ef-fectively by HPLC fingerprint.%目的:采用RP-HPLC法建立蓝萼香茶菜药材的指纹图谱. 方法:采用Diamonsil钻石C18色谱柱(250 mm ×4.6 mm, 5μm);流动相为甲醇-水(体积比70:30),流速为1.0 mL/min,柱温为20℃,检测波长为231 nm. 结果:建立了蓝萼香茶菜药材的RP-HPLC指纹图谱,5批蓝萼香茶菜药材指纹图谱R≥0.962 7.结论:采用RP-HPLC指纹图谱检测技术可以有效控制蓝萼香茶菜药材的内在质量.

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

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


    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.

  17. Multidimensional high-performance liquid chromatography on Pinkerton ISRP and RP18 columns: direct serum injection to quantify creatinine. (United States)

    Puhlmann, A; Dülffer, T; Kobold, U


    A two-dimensional high-performance liquid chromatographic method for the determination of creatinine with direct serum injection without sample pretreatment has been developed. The column-switching technique allowed a switch from columns packed with internal surface reversed-phase (ISRP) material to columns of almost any other material, even if the eluents necessary in a particular case do not appear to be directly compatible. A Pinkerton ISRP column, which stands out because of its very good stability when loaded with undiluted serum samples, was used as precolumn. The creatinine-containing fraction was switched to a reversed-phase Shandon RP18 column and was focused there by alteration of the eluent from pH 6.5 to phosphoric acid-ion-pair reagent. The separation occurs via a pH gradient, with ultraviolet detection at 234 nm. This method stands out particularly for its good long-term stability, simple sample handling without pretreatment, high selectivity, a broad linearity (0.3-30 mg/dl creatinine), good reproducibility (inter-assay coefficient of variation less than 3%) and high recovery (97-100%) relative to values obtained with gas chromatography-mass spectrometry.

  18. Refolding and simultaneous purification of recombinant human proinsulin from inclusion bodies on protein-folding liquid-chromatography columns. (United States)

    Yuan, Jie; Zhou, Huifang; Yang, Yicong; Li, Weimin; Wan, Yi; Wang, Lili


    Protein-folding liquid chromatography (PFLC) is an effective and scalable method for protein renaturation with simultaneous purification. However, it has been a challenge to fully refold inclusion bodies in a PFLC column. In this work, refolding with simultaneous purification of recombinant human proinsulin (rhPI) from inclusion bodies from Escherichia coli were investigated using the surface of stationary phases in immobilized metal ion affinity chromatography (IMAC) and high-performance size-exclusion chromatography (HPSEC). The results indicated that both the ligand structure on the surface of the stationary phase and the composition of the mobile phase (elution buffer) influenced refolding of rhPI. Under optimized chromatographic conditions, the mass recoveries of IMAC column and HPSEC column were 77.8 and 56.8% with purifies of 97.6 and 93.7%, respectively. These results also indicated that the IMAC column fails to refold rhPI, and the HPSEC column enables efficient refolding of rhPI with a low-urea gradient-elution method. The refolded rhPI was characterized by circular dichroism spectroscopy. The molecular weight of the converted human insulin was further confirmed with SDS-18% PAGE, Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) and the biological activity assay by HP-RPLC.

  19. Ultrafast UPLC-ESI-MS and HPLC with monolithic column for determination of principal flavor compounds in vanilla pods. (United States)

    Sharma, Upendra K; Sharma, Nandini; Sinha, Arun K; Kumar, Neeraj; Gupta, Ajai P


    In this study, two novel chromatographic methods based on monolithic column high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC) were developed for the ultrafast determination of principal flavor compounds namely vanillin, vanillic acid, p-hydroxybenzoic acid, and p-hydroxybenzaldehyde in ethanolic extracts of Vanilla planifolia pods. Good separation was achieved within 2.5 min using Chromolith RP18e column (100 mm x 4.6 mm) for HPLC and Acquity BEH C-18 (100 mm x 2.1 mm, 1.7 microm) column for UPLC. Both methods were compared in terms of total analysis time, mobile phase consumption, sensitivity, and validation parameters like precision, accuracy, LOD, and LOQ. Further, system suitability test data including resolution, capacity factor, theoretical plates, and tailing factor was determined for both the methods by ten replicate injections. Monolithic column based HPLC gave better results for most of the selected parameters while UPLC was found to be more eco-friendly with low mobile phase consumption and better sensitivity. Both methods may be used conveniently for the high throughput analysis of large number of samples in comparison to traditional particulate column.

  20. Single-walled carbon nanotube-based polymer monoliths for the enantioselective nano-liquid chromatographic separation of racemic pharmaceuticals. (United States)

    Ahmed, Marwa; Yajadda, Mir Massoud Aghili; Han, Zhao Jun; Su, Dawei; Wang, Guoxiu; Ostrikov, Kostya Ken; Ghanem, Ashraf


    Single-walled carbon nanotubes were encapsulated into different polymer-based monolithic backbones. The polymer monoliths were prepared via the copolymerization of 20% monomers, glycidyl methacrylate, 20% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) or 16.4% monomers (16% butyl methacrylate, 0.4% sulfopropyl methacrylate), 23.6% ethylene glycol dimethacrylate and 60% porogens (36% 1-propanol, 18% 1,4-butanediol) along with 6% single-walled carbon nanotubes aqueous suspension. The effect of single-walled carbon nanotubes on the chiral separation of twelve classes of pharmaceutical racemates namely; α- and β-blockers, antiinflammatory drugs, antifungal drugs, dopamine antagonists, norepinephrine-dopamine reuptake inhibitors, catecholamines, sedative hypnotics, diuretics, antihistaminics, anticancer drugs and antiarrhythmic drugs was investigated. The enantioselective separation was carried out under multimodal elution to explore the chiral recognition capabilities of single-walled carbon nanotubes using reversed phase, polar organic and normal phase chromatographic conditions using nano-liquid chromatography. Baseline separation was achieved for celiprolol, chlorpheniramine, etozoline, nomifensine and sulconazole under multimodal elution conditions. Satisfactory repeatability was achieved through run-to-run, column-to-column and batch-to-batch investigations. Our findings demonstrate that single-walled carbon nanotubes represent a promising stationary phase for the chiral separation and may open the field for a new class of chiral selectors.

  1. Chromatographic fingerprint analysis and simultaneous determination of eight lignans in Justicia procumbens and its compound preparation by HPLC-DAD. (United States)

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


    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.

  2. Development and Validation of Stability-indicating High Performance Liquid Chromatographic Method for the Estimation of Everolimus in Tablets. (United States)

    Sharmila, D; Rao, A Lakshmana; Kalyani, L


    The present study depicts the development of a validated reversed-phase high performance liquid chromatographic method for the determination of the everolimus in presence of degradation products or pharmaceutical excipients. Stress study was performed on everolimus and it was found that it degrade sufficiently in oxidizing and acidic conditions but less degradation was found in alkaline, neutral, thermal and photolytic conditions. The separation was carried out on Hypersil BDS C18 column (100×4.6 mm, 5 μ) column having particle size 5 μ using acetate buffer:acetonitrile (50:50 v/v) with pH 6.5 adjusted with orthophosphoric acid as mobile phase at flow rate of 1 ml/min. The wavelength of the detection was 280 nm. A retention time (Rt) nearly 3.110 min was observed. The calibration curve for everolimus was linear (r(2)=0.999) from range of 25-150 μg/ml with limit of detection and limit of quantification of 0.036 μg/ml and 0.109 μg/ml, respectively. Analytical validation parameters such as selectivity, specificity, linearity, accuracy and precision were evaluated and relative standard deviation value for all the key parameters were less than 2.0%. The recovery of the drug after standard addition was found to be 100.55%. Thus, the developed RP-HPLC method was found to be suitable for the determination of everolimus in tablets containing various excipients.

  3. Development and validation of a rapid liquid chromatographic method for the determination of oxatomide and its related impurities. (United States)

    Curtin Whelan, Laura; Geary, Michael; Sweetman, Paul


    A rapid liquid chromatographic method was developed for the determination of oxatomide in its finished active pharmaceutical ingredient form and in the presence of its process impurities. The method was developed on a sub 2 µm Hypersil Zorbax XDB C18 column (30 × 4.6 mm, i.d., 1.8 µm). The rapid method employed a gradient mobile phase consisting of solvent A: 0.01 M tetrabutylammonium hydrogen sulfate and 0.5% (w/v) ammonium acetate in water and solvent B: acetonitrile. A flow rate of 2 mL/min was employed with the diode-array detector set at 230 nm. The original method supplied by Janssen Pharmaceuticals Ltd was run on a Thermo Scientific octadecylsilyl silica gel C18 column (100 × 4.6 mm, i.d., 5 µm) with an analysis time of 20 min. The main aim was to substantially reduce the analysis time while maintaining good efficiency. Run-time was reduced to 6.5 min with a total loss in analysis time of 68%. Solvent consumption was also reduced by 68%. Validation according to the International Conference of Harmonization guidelines was undertaken. The parameters examined were accuracy, precision, linearity, selectivity, robustness, limit of detection and limit of quantification; all criteria were met. Sample stability testing was also carried out. Oxatomide proved stable under ambient and 4°C temperatures and in the presence of light for up to 24 h.

  4. Fast gas chromatographic residue analysis in animal feed using split injection and atmospheric pressure chemical ionisation tandem mass spectrometry. (United States)

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


    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.

  5. [A reversed-phase high performance liquid chromatographic method for the determination of pinoresinol diglucopyranoside in Eucommia Ulmoides Oliv]. (United States)

    Qi, X; Zhang, S


    A reversed-phase high performance liquid chromatographic method for the determination of (+)-pinoresinol-di-O-beta-D-glucopyranoside in the bark of Eucommia Ulmoides was established. The air-dried bark of E. Ulmoides was ground into powder and extracted continuously with methanol. The extract was evaporated under reduced pressure, then suspended in water. This suspension being subjected to column chromatography was eluted successively with water, 30%, 50% and 90% aqueous solution of ethanol. The 30% EtOH eluate was concentrated and then injected into HPLC system. The conditions of HPLC were: YWG-C18 column (250 mm x 4.6 mm i.d. 10 microns); 28%(V/V) methanol mobile phase and UV detector at 232 nm. The calibration curve was linear in the range of 0.068 microgram-0.68 microgram of(+)-pinoresinol-di-O-beta-D-glucopyranoside with correlation coefficient of 0.9999. The coefficient of variation and average recovery were 0.50%-0.74% (n = 5) and 99.22% (n = 3) respectively.

  6. Application of Analytical Quality by Design concept for bilastine and its degradation impurities determination by hydrophilic interaction liquid chromatographic method. (United States)

    Terzić, Jelena; Popović, Igor; Stajić, Ana; Tumpa, Anja; Jančić-Stojanović, Biljana


    This paper deals with the development of hydrophilic interaction liquid chromatographic (HILIC) method for the analysis of bilastine and its degradation impurities following Analytical Quality by Design approach. It is the first time that the method for bilastine and its impurities is proposed. The main objective was to identify the conditions where an adequate separation in minimal analysis duration could be achieved within a robust region. Critical process parameters which have the most influence on method performance were defined as acetonitrile content in the mobile phase, pH of the aqueous phase and ammonium acetate concentration in the aqueous phase. Box-Behnken design was applied for establishing a relationship between critical process parameters and critical quality attributes. The defined mathematical models and Monte Carlo simulations were used to identify the design space. Fractional factorial design was applied for experimental robustness testing and the method is validated to verify the adequacy of selected optimal conditions: the analytical column Luna(®) HILIC (100mm×4.6mm, 5μm particle size); mobile phase consisted of acetonitrile-aqueous phase (50mM ammonium acetate, pH adjusted to 5.3 with glacial acetic acid) (90.5:9.5, v/v); column temperature 30°C, mobile phase flow rate 1mLmin(-1), wavelength of detection 275nm.

  7. Single-walled carbon nanotubes as stationary phase in gas chromatographic separation and determination of argon, carbon dioxide and hydrogen. (United States)

    Safavi, Afsaneh; Maleki, Norooz; Doroodmand, Mohammad Mahdi


    A chromatographic technique is introduced based on single-walled carbon nanotubes (SWCNTs) as stationary phase for separation of Ar, CO(2) and H(2) at parts per million (ppm) levels. The efficiency of SWCNTs was compared with solid materials such as molecular sieve, charcoal, multi-walled carbon nanotubes and carbon nanofibers. The morphology of SWCNTs was optimized for maximum adsorption of H(2), CO(2) and Ar and minimum adsorption of gases such as N(2), O(2), CO and H(2)O vapour. To control temperature of the gas chromatography column, peltier cooler was used. Mixtures of Ar, CO(2) and H(2) were separated according to column temperature program. Relative standard deviation for nine replicate analyses of 0.2 mL H(2) containing 10 microL of each Ar or CO(2) was 2.5% for Ar, 2.8% for CO(2) and 3.6% for H(2). The interfering effects of CO, and O(2) were investigated. Working ranges were evaluated as 40-600 ppm for Ar, 30-850 ppm for CO(2) and 10-1200 ppm for H(2). Significant sensitivity, small relative standard deviation (RSD) and acceptable limit of detection (LOD) were obtained for each analyte, showing capability of SWCNTs for gas separation and determination processes. Finally, the method was used to evaluate the contents of CO(2) in air sample.

  8. Development and validation of a gas chromatographic method for the assay of memantine hydrochloride in pure and tablet dosage forms

    Directory of Open Access Journals (Sweden)

    Siddappa K.


    Full Text Available A gas chromatographic method has been developed and validated for the determination of memantine hydrochloride (MMT in pure and pharmaceutical preparations. The detection was carried out using flame ionization detector. Separation was achieved on a DB-624 fused silica packed capillary column (30 m x 0.320 mm x 1.8 μm. Nitrogen was used as a carrier gas at a flow rate of 40 mL/min. The column temperature was maintained at 300°C while the temperature of injection port and detector were maintained at 270° and 300°C, respectively. Gabapentin (GPN was used as an internal standard. The procedure gave a linear response over the concentration range of 0.5-3.5 mg/mL with sufficient reproducibility. The method has been applied successfully for the determination of MMT in pure and pharmaceutical formulations. The excipients present in the formulations did not interfere with the assay procedure. The recovery values were found to be in the range of 99.85-100.1% with RSD values less than 1%. The results obtained from this method were compared with the reference method (HPTLC reported in literature and no significant difference was found statistically.

  9. Five-descriptor model to predict the chromatographic sequence of natural compounds. (United States)

    Hou, Shuying; Wang, Jinhua; Li, Zhangming; Wang, Yang; Wang, Ying; Yang, Songling; Xu, Jia; Zhu, Wenliang


    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.

  10. Chromatographic separation of bioactive oxycholesterols by GC, HPLC and SFC. (United States)

    McAllister, Heather; Wu, Jiejun


    In this paper we report the development of chromatographic methods for the separation of 8 biologically active hydroxycholesterols (OHC's) which include the single-hydroxyl addition species 7α-OHC, 7β-OHC, 25-OHC and 27- OHC, together with the double-hydroxyl addition species 7α, 25-OHC, 7β, 25-OHC, 7α, 27-OHC, and 7β, 27-OHC. Four complementary techniques were employed (gas chromatography, normal phase and reversed phase high performance liquid chromatography, and supercritical fluid chromatography), and for each of the techniques, an optimized method for the separation of all eight compounds in a mixture is presented.

  11. Chromatographic zinc isotope separation by phenol formaldehyde benzo crown resin. (United States)

    Ding, Xingcheng; Nomura, Masao; Suzuki, Tatsuya; Sugiyama, Yuichi; Kaneshiki, Toshitaka; Fujii, Yasuhiko


    New types of phenol formaldehyde resin having benzo crown as a functional group were synthesized and applied to zinc isotope chromatographic operation. Zinc adsorption and isotope separation capacities were dramatically improved by using phenol formaldehyde benzo-15-crown-5 resin. Zinc batch adsorption tests were performed by various dehydrated organic solvents. Separation coefficient, epsilon 8.1 x 10(-4) and height equivalent to a theoretical plate (HETP) 0.105 cm for the isotopic pair of 68Zn/64Zn in phenol formaldehyde benzo-15-crown-5 resin were obtained in the case of acetone as the solvent at 298+/-1K.

  12. Reversal of elution order for profen acid enantiomers in packed-column SFC on Chiralpak AD. (United States)

    Gyllenhaal, Olle; Stefansson, Morgan


    Enantiomeric separations of four 2-substituted propionic acid drugs have been studied using packed-column supercritical fluid chromatography (SFC) with amylose tris(3,5-dimethylphenylcarbamate) coated on silica as support (Chiralpak AD). Under standard conditions (i.e., flow rate, 1.5 ml/min; column temperature, 30 degrees C; back-pressure, 150 bar), the order of elution could be reversed when the polar alcohol modifier methanol in carbon dioxide was replaced by 2-propanol for ibuprofen, ketoprofen, and naproxen. For flurbiprofen, with the highest selectivity factor, no reversal was observed, although selectivity was reduced significantly with higher alcohols. Naproxen and flurbiprofen were also investigated with 2-butanol and 2-pentanol. The former showed reversal of elution order but not the latter. For higher alcohol modifiers, including 2-propanol, the peak symmetry was poor but could be improved by addition of citric acid in the alcohol modifier. These results stress the importance to investigate enantiomer elution order during the development of enantioselective methods and when chromatographic conditions are optimized. Preliminary experiments with column temperatures over the range of -15 to 45 degrees C revealed that, in a few cases, reversal took place with a change in temperature only.

  13. The setup of an extraction system coupled to a hydrogen isotopes distillation column

    Energy Technology Data Exchange (ETDEWEB)

    Zamfirache, M.; Bornea, A.; Stefanescu, I.; Bidica, N.; Balteanu, O.; Bucur, C. [INC-DTCI, ICSIRm. Valcea, Uzinei Street 4, Rm. Valcea (Romania)


    Among the most difficult problems of cryogenic distillation one stands apart: the extraction of the heavy fraction. By an optimal design of the cycle scheme, this problem could be avoided. A 'worst case scenario' is usually occurring when the extracted fraction consists of one prevalent isotope such as hydrogen and small amounts of the other two hydrogen isotopes (deuterium and/or tritium). This situation is further complicated by two parameters of the distillation column: the extraction flow rate and the hold-up. The present work proposes the conceptual design of an extraction system associated to the cryogenic distillation column used in hydrogen separation processes. During this process, the heavy fraction (DT, T{sub 2}) is separated, its concentration being the highest at the bottom of the distillation column. From this place the extraction of the gaseous phase can now begin. Being filled with adsorbent, the extraction system is used to temporarily store the heavy fraction. Also the extraction system provides samples for the gas Chromatograph. The research work is focused on the existent pilot plant for tritium and deuterium separation from our institute to validate the experiments carried out until now. (authors)

  14. Direct injection HPLC method for the determination of selected benzodiazepines in plasma using a Hisep column. (United States)

    Pistos, C; Stewart, James T


    A direct plasma injection HPLC method has been developed for the determination of selected benzodiazepines (nitrazepam, clobazam, oxazepam, lorazepam). The method uses an analytical hydrophobic shielded phase (Hisep) column equipped with a Hisep guard column, are easy to perform and requires 20 ul of a filtered plasma sample. The chromatographic run time is less than 15 min using a mobile phase of 15:85 v/v acetonitrile-0.18 M ammonium acetate pH 2.5. The method is good for 175 injections before replacement of the guard column. The method was linear in the range 0.5-18 ug ml(-1) (r>0.99, n=6) for the analytes with R.S.D. less than 10.82%. Interday and intraday variability were found to be less than 14%. The limits of detection and quantitation were 0.16 (s/n>3) and 0.5 ug ml(-1) (s/n>10), respectively, for each of the four benzodiazepines.

  15. Temperature Control of Gas Chromatograph Based on Switched Delayed System Techniques

    Directory of Open Access Journals (Sweden)

    Xiao-Liang Wang


    Full Text Available We address the temperature control problem of the gas chromatograph. We model the temperature control system of the gas chromatograph into a switched delayed system and analyze the stability by common Lyapunov functional technique. The PI controller parameters can be given based on the proposed linear matrix inequalities (LMIs condition and the designed controller can make the temperature of gas chromatograph track the reference signal asymptotically. An experiment is given to illustrate the effectiveness of the stability criterion.

  16. Highly efficient capillary columns packed with superficially porous particles via sequential column packing. (United States)

    Treadway, James W; Wyndham, Kevin D; Jorgenson, James W


    Highly efficient capillary columns packed with superficially porous particles were created for use in ultrahigh pressure liquid chromatography. Superficially porous particles around 1.5μm in diameter were packed into fused silica capillary columns with 30, 50, and 75μm internal diameters. To create the columns, several capillary columns were serially packed from the same slurry, with packing progress plots being generated to follow the packing of each column. Characterization of these columns using hydroquinone yielded calculated minimum reduced plate heights as low as 1.24 for the most efficient 30μm internal diameter column, corresponding to over 500,000plates/m. At least one highly efficient column (minimum reduced plate height less than 2) was created for all three of the investigated column inner diameters, with the smallest diameter columns having the highest efficiency. This study proves that highly efficient capillary columns can be created using superficially porous particles and shows the efficiency potential of these particles.

  17. Evaluation of mobile phase characteristics on three zwitterionic columns in hydrophilic interaction liquid chromatography mode for liquid chromatography-high resolution mass spectrometry based untargeted metabolite profiling of Leishmania parasites. (United States)

    Zhang, Rong; Watson, David G; Wang, Lijie; Westrop, Gareth D; Coombs, Graham H; Zhang, Tong


    It has been reported that HILIC column chemistry has a great effect on the number of detected metabolites in LC-HRMS-based untargeted metabolite profiling studies. However, no systematic investigation has been carried out with regard to the optimisation of mobile phase characteristics. In this study using 223 metabolite standards, we explored the retention mechanisms on three zwitterionic columns with varied mobile phase composition, demonstrated the interference from poor chromatographic peak shapes on the output of data extraction, and assessed the quality of chromatographic signals and the separation of isomers under each LC condition. As expected, on the ZIC-cHILIC column the acidic metabolites showed improved chromatographic performance at low pH which can be attributed to the opposite arrangement of the permanently charged groups on this column in comparison with the ZIC-HILIC column. Using extracts from the protozoan parasite Leishmania, we compared the numbers of repeatedly detected LC-HRMS features under different LC conditions with putative identification of metabolites not amongst the standards being based on accurate mass (±3ppm). Besides column chemistry, the pH of the mobile phase plays a key role in not only determining the retention mechanisms of solutes but also the output of the LC-HRMS data processing. Fast evaporation of ammonium carbonate produced less ion suppression in ESI source and consequently improved the detectability of the metabolites in low abundance in comparison with other ammonium salts. Our results show that the combination of a ZIC-pHILIC column with an ammonium carbonate mobile phase, pH 9.2, at 20mM in the aqueous phase or 10mM in both aqueous and organic mobile phase components, provided the most suitable LC conditions for LC-HRMS-based untargeted metabolite profiling of Leishmania parasite extracts. The signal reliability of the mass spectrometer used in this study (Exactive Orbitrap) was also investigated.

  18. Determination of Imidacloprid and metabolites by liquid chromatography with an electrochemical detector and post column photochemical reactor

    Energy Technology Data Exchange (ETDEWEB)

    Rancan, M. [Consiglio per la Ricerca e la Sperimentazione in Agricoltura (CRA), Istituto Nazionale di Apicoltura, Via di Saliceto 80, I-40128 Bologna (Italy)]. E-mail:; Sabatini, A.G. [Consiglio per la Ricerca e la Sperimentazione in Agricoltura (CRA), Istituto Nazionale di Apicoltura, Via di Saliceto 80, I-40128 Bologna (Italy); Achilli, G. [Euroservice s.r.l., Piazza Maggiolini 3A, I-20015 Parabiago, Milan (Italy); Galletti, G.C. [Dipartimento di Chimica ' G.Ciamician' , University of Bologna, Via F. Selmi 2, I-40126 Bologna (Italy)


    A procedure for the determination of Imidacloprid and its main metabolites was set up by means of liquid chromatography with an electrochemical detector and post-column photochemical reactor (LC-h{nu}-ED). Sample clean-up was developed for bees, filter paper and maize leaves. Chromatographic conditions were based on a reversed-phase C-18 column operated by phosphate buffer 50 mM/CH{sub 3}CN (80/20, v/v) at pH 2.9. Detection of Imidacloprid and its metabolites was performed at a potential of 800 mV after photoactivation at 254 nm. Compared to conventional techniques such as gas chromatography/mass spectrometry (GC/MS) or LC coupled to other detectors, the present method allows simultaneous trace-level determination of both Imidacloprid (0.6 ng ml{sup -1}) and its main metabolites (2.4 ng ml{sup -1})

  19. Adsorption behavior of plasmid DNA onto perfusion chromatographic matrix

    Institute of Scientific and Technical Information of China (English)



    Anion exchange chromatography is the most popular chromatographic method for plasmid separa-tion.POROS RI 50 is a perfusion chromatographic support which is a reversed phase matrix and is an alterna-tive to conventional ones due to its mass transfer properties.The adsorption and elution of the pIDKE2 plasmidonto reversed phase POROS RI 50 was studied.Langmuir isotherm model was adjusted in order to get the max-imum adsorption capacity and the dissociation constant for POROS RI 50-plasmid DNA (pDNA) system.Break-through curves were obtained for volumetric flows between 0.69-3.33mL/min,given dynamic capacity up to2.3 times higher than those reported for ionic exchange matrix used during the purification process of plasmidswith similar size to that of pIDKE2.The efficiency was less than 45% for the flow conditions and initial concen-tration studied,which means that the support will not be operated under saturation circumstances.

  20. Size-exclusion chromatographic NMR under HR-MAS. (United States)

    Lucena Alcalde, Guillermo; Anderson, Natalie; Day, Iain J


    The addition of stationary phases or sample modifiers can be used to modify the separation achievable in the diffusion domain of diffusion NMR experiments or provide information on the nature of the analyte-sample modifier interaction. Unfortunately, the addition of insoluble chromatographic stationary phases can lead to line broadening and degradation in spectral resolution, largely because of differences in magnetic susceptibility between the sample and the stationary phase. High-resolution magic angle spinning (HR-MAS) techniques can be used to remove this broadening. Here, we attempt the application of HR-MAS to size-exclusion chromatographic NMR with limited success. Observed diffusion coefficients for polymer molecular weight reference standards are shown to be larger than those obtained on static samples. Further investigation reveals that under HR-MAS it is possible to obtain reasonably accurate estimates of diffusion coefficients, using either full rotor synchronisation or sophisticated pulse sequences. The requirement for restricting the sample to the centre of the MAS rotor to ensure homogeneous magnetic and RF fields is also tested. Copyright © 2016 John Wiley & Sons, Ltd.

  1. Gas chromatographic determination of chloramphenicol residues in shrimp: interlaboratory study. (United States)

    Munns, R K; Holland, D C; Roybal, J E; Storey, J M; Long, A R; Stehly, G R; Plakas, S M


    An interlaboratory study of a gas chromatographic method for determining chloramphenicol (CAP) residues in shrimp was conducted. An internal standard (Istd), the meta isomer of CAP, was added to the shrimp, and the treated shrimp were homogenized with ethyl acetate. The ethyl acetate extract was defatted with hexane, and the CAP was partitioned into ethyl acetate from an aqueous salt solution. The ethyl acetate was evaporated, and the dried residue was treated with Sylon, a trimethylsilyl derivatizing agent, to yield the trimethylsilyl derivative of CAP. A portion of the solution containing the derivative was injected into a gas chromatograph equipped with an electron capture detector. Levels of fortified and incurred CAP were calculated from the peak area ratio of standard CAP to Istd. Recoveries of CAP from tissue directly fortified at 5 ppb were 102% (within-laboratory relative standard deviation [RSDr] = 5.6%), 104% (RSDr = 5.5%), and 108% (RSDr = 6.3%) from Laboratories 1, 2, and 3, respectively. Incurred-CAP residues at 5 and 10 ppb levels were also determined, with the following results: Laboratory 1: composite A, 4.56 ppb (RSDr = 14.0%); composite B, 8.38 ppb (RSDr = 11.6%); Laboratory 2: composite A, 4.17 ppb (RSDr = 12.5%); composite B, 8.90 ppb (RSDr = 5.60%); Laboratory 3: composite A, 4.66 ppb (RSDr = 14.9%); composite B, 11.0 ppb (RSDr = 11.8%).


    Institute of Scientific and Technical Information of China (English)

    WangHaifeng; XuYutai; 等


    Separation and purification of human chorionic gonadotropion(HCG) in the urine sample of early pregnant women by D3520 resin adsorption chromatography is reported.The crude product obtained by DEAE-Cellulose 23 and DEAE-Sephadex A50 column chromatography showed a high activity of HCG. Further purification of the sample by gel filtration chromatography on a Sephadex G75 column gives a final preparation of 6000-6500 IU/mg.The preparation meets the requirements of the pyrogn test in Chinese Law of Pharmacopeia.

  3. 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. (United States)

    Szopa, C; Sternberg, R; Coscia, D; Raulin, F; Vidal-Madjar, C


    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.

  4. New chiral reverse phase HPLC method for enantioselective analysis of ketorolac using chiral AGP column

    Institute of Scientific and Technical Information of China (English)

    Sunil K. Dubey; Jangala Hemanth; Chiranjeevi Venkatesh K.; R.N. Saha; S. Pasha


    A simple, specific, precise, sensitive and rapid reverse phase-HPLC method was developed for determination of ketorolac enantiomers, a potent nonnarcotic analgesic in pharmaceutical formulations. The method was developed on a chiral AGP column. Mobile phase was 0.1 M sodium phosphate buffer (pH 4.5): lsopropanol (98:2, v/v), at a flow rate of 1 mL/min with run time of 15 min. Ultraviolet detection was made at 322 nm. The linearity range was 0.02 10 μg/mL for each of the enantiomers. The mobile phase composition was systematically studied to find the optimum chromatographic conditions. Validation of the method under the conditions selected showed that it was selective and precise and that the detector response was linear function of ketorolac.

  5. Extra-column dispersion of macromolecular solutes in aqueous-phase size-exclusion chromatography. (United States)

    Grznárová, G; Polakovic, M; Acai, P; Görner, T


    A set of dextran standards was used to study the extra-column dispersion in conventional chromatographic equipment at a broad range of molecular weights, different mobile phase flow rates and connecting tube lengths and diameters. All known correlations for the tube dispersion at laminar flow, including those for short tubes, overestimated the values of the variance of the outlet concentration signal. The difference increased with the solute molecular weight and the flow rate. It was assumed that the discrepancy was due to the effect of natural convection invoked by the density differences of the injected dextran solutions and water. A suitable approximation of the relative band spreading was suggested in a form of a power function of the Reynolds and Schmidt numbers. A significant decrease of the dispersion was observed when the chromatography tubing was coiled into a circle. This decrease was successfully predicted combining the existing correlations for long coiled tubes and short straight tubes.

  6. Determination of Five Organic Acids in Radix Isatidis by Column Partition Chromatography and Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    CHAIYi-fen; JISong-gang; ZHANGGuo-qing; LIUChang-hai


    Aim To determine five organic acids in Radix lsatidis. Method The extraction method and the column partition chromatographic conditiom were studied. Then a capillary zone dectrophorefic method was set up for the determina-tion. Results The linear ranges of quinazolinone acid, n-anthranilic acid, benzoic acid, salicylic acid, and syringic acid were 5.52 - 92.0μg·mL-1 , 5.12 - 102μg·mL-1 , 2.28 - 84.4μg·mL-1, 4.78 - 159 μg·mL-1, and 1.74- 87.0μg·mL-1 respectively. Conclusion The established method is accurate and simple.

  7. Preparation of a biomimetic polyphosphorylcholine monolithic column for immobilized artificial membrane chromatography. (United States)

    Zhao, XiangLong; Chen, WeiJia; Zhou, ZhengYin; Wang, QiQin; Liu, ZhengHua; Moaddel, Ruin; Jiang, ZhengJin


    The present work aims to prepare a novel phosphatidylcholine functionalized monolithic stationary phase by in situ co-polymerization of 12-methacryloyl dodecylphosphocholine (MDPC) and ethylene dimethacrylate (EDMA) for immobilized artificial membrane chromatography. Scanning electron microscopy, energy dispersive X-ray spectroscopy, FT-IR spectroscopy, pore size distribution analysis, ζ-potential analysis and micro-HPLC were used to evaluate the monolithic structure and physicochemical properties. Satisfactory morphology, high mechanical stability, good permeability and chromatographic performance were obtained on the optimized monolithic columns. A typical reverse-phase retention mechanism was observed over a wide range of organic solvent content (acetonitrilecolumn (IAM.PC.DD2) and poly(MDPC-co-EDMA) monolith. This novel poly(MDPC-co-EDMA) monolith exhibited good potential for studying the drug-membrane interaction.

  8. An innovative monolithic column preparation for the isolation of 25 kilo base pairs DNA. (United States)

    Ongkudon, Clarence M; Pan, Sharadwata; Danquah, Michael K


    The use of large DNAs in preparing multivalent vaccines that will eventually give protective immunity against multiple pathogenic microbes is becoming a major debate nowadays. One of the important issues in ensuring the successful implementation of the new vaccine technology is the development of a chromatographic technique that can handle larger DNAs. This paper reports the development of a novel conical monolithic column format with pore and surface characteristics engineered for the isolation of 25 kbp DNA in a single step fashion. An effective method of eliminating wall channelling, a defect of most conventional monolithic chromatography systems which has caused significant loss of product, was applied to maximise DNA recovery. This method was based on a systematic reduction of wall channel size based on a predetermined correlation between column’s back pressure and wall channel size of a particular monolith pore size.

  9. Electroosmotic Driving Liquid Using Nanosilica Packed Column

    Institute of Scientific and Technical Information of China (English)

    Ling Xin CHEN; Guo An LUO; Tao WEN


    The electroosmotic pump (EOP) using nanosilica particles packed-bed column was experimentally studied. The relationship between flowrate, pressure and applied voltage of the pump, and pressure-flowrate (P-Q) characteristic were investigated.

  10. Early development of the vertebral column. (United States)

    Scaal, Martin


    The segmental organization of the vertebrate body is most obviously visible in the vertebral column, which consists of a series of vertebral bones and interconnecting joints and ligaments. During embryogenesis, the vertebral column derives from the somites, which are the primary segments of the embryonic paraxial mesoderm. Anatomical, cellular and molecular aspects of vertebral column development have been of interest to developmental biologists for more than 150 years. This review briefly summarizes the present knowledge on early steps of vertebral column development in amniotes, starting from sclerotome formation and leading to the establishment of the anatomical bauplan of the spine composed of vertebral bodies, vertebral arches, intervertebral discs and ribs, and their specific axial identities along the body axis.

  11. Extraction chromatographic separation of Sr, Pu and Am in environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, Rajdeep


    An accurate determination of radionuclides from various sources in the environment is essential for assessment of the potential hazards and suitable countermeasures both in case of an authorised release, accidents and routine surveillance. Due to the short range of alpha and beta radiation, the accurate determination of pure alpha and beta emitters must always include radiochemical separations to separate the analytes from the matrix and from other interfering stable and radioactive nuclides. Hence, the procedures used for their determination are usually tedious and involve several preconcentration and separation steps. This work deals with the determination of {sup 90}Sr, {sup 241}Am, {sup 238}Pu, {sup 239,240}Pu and {sup 244}Cm, whic some of the most important artificial radionuclides. Due to either absence or low yield of gamma radiation, a secure determination of low concentrations of all these nuclides requires a dedicated chemistry. Selective extraction chromatographic resins (TRU- and Sr-Resin) have been utilised to develop new procedures for the analyses of Pu, Am and Cm isotopes in seawater and both these and {sup 90}Sr in soil, sediment, urine and low-level liquid radioactive effluents. The proposed method for the analyses of Pu and Am in seawater offers a quick and secure mode for the determination of these radionuclides in marine waters. Combined pre-concentration of actinides and strontium (oxalate or phosphate precipitation) followed by dual column separation on TRU- and Sr-Resin significantly reduces the through put time and costs compared to traditional ion exchange and precipitation methods. The greatest gain in productivity and environmental friendliness is achieved in Sr separations using Sr-Resin instead of precipitations involving fuming nitric acid and oxalate, hydroxide, chromate and carbonate precipitations. (author)

  12. High-performance liquid chromatographic determination of memantine hydrochloride in rat plasma using sensitive fluorometric derivatization. (United States)

    Xie, Mei-Fen; Zhou, Wei; Tong, Xin-Yi; Chen, Yi-Le; Cai, Yi; Li, Yan; Duan, Geng-Li


    In this study, we investigated a simple, sensitive and reliable liquid chromatography-fluorescence detection method for the determination of memantine hydrochloride in rat plasma which was based on derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). For the first time, FMOC-Cl was introduced into derivatization of memantine hydrochloride in rat plasma. The amino groups of memantine hydrochloride and amantadine hydrochloride (internal standard) were trapped with FMOC-Cl to form memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions, which can be very compatible for LC-FLD. Precipitation of plasma proteins by acetonitrile was followed by vortex mixing and centrifugation. Chromatographic separation was performed on a C(18) column (DIAMONSIL 150 × 4.6 mm, id 5 μm) with a mobile phase consisting of acetonitrile and water at a flow rate of 1.0 mL/min. The retention times of memantine hydrochloride-FMOC-Cl and amantadine hydrochloride-FMOC-Cl compositions were 23.69 and 40.27 min, respectively. Optimal conditions for the derivatization of memantine hydrochloride were also described. The limit of quantification (LOQ) was 25 ng/mL for memantine hydrochloride in plasma, the linear range was 0.025-5.0 μg/mL in plasma with a correlation coefficient (r) of 0.9999. The relative standard deviations (RSDs) of intra-day and inter-day assays were 4.46-12.19 and 5.23-11.50%, respectively. The validated method was successfully applied to the determination of memantine hydrochloride in rat plasma samples.

  13. Validation of stability indicating high performance liquid chromatographic method for estimation of Desloratadine in tablet formulation

    Directory of Open Access Journals (Sweden)

    R.B. Patel


    Full Text Available A simple, sensitive and specific stability indicating high performance liquid chromatographic (HPLC method for the estimation of Desloratadine was developed and validated. Desloratadine was separated and quantitated on Inertsil ODS-3 V column (250 mm length, 4.6 mm id, 5 μm particle size using a mixture of methanol–phosphate buffer of pH 7.0 (70:30 v/v as a mobile phase and at a flow rate of 1.0 mL/min. Quantification was achieved with an UV detector at 254 nm over the concentration range of 5–75 μg/mL. The applied HPLC method allowed the separation and quantification of Desloratadine with good linearity (r2 = 0.999 in the studied concentration range. Limit of detection and limit of quantification were found to be 1.28 μg/mL and 3.89 μg/mL, respectively. The method was validated as per the International Conference on Harmonization (ICH guidelines. Desloratadine stock solution was subjected to different stress conditions. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. Stressed samples were assayed using developed HPLC method. Statistical analysis of the data showed that the method is precise, accurate, reproducible, and selective for the analysis of Desloratadine. The method was successfully applied to the estimation of Desloratadine in tablet dosage form.

  14. Modeling Tropical Precipitation in a Single Column. (United States)

    Sobel, Adam H.; Bretherton, Christopher S.


    A modified formulation of the traditional single column model for representing a limited area near the equator is proposed. This formulation can also be considered a two-column model in the limit as the area represented by one of the columns becomes very large compared to the other. Only a single column is explicitly modeled, but its free tropospheric temperature, rather than its mean vertical velocity, is prescribed. This allows the precipitation and vertical velocity to be true prognostic variables, as in prior analytical theories of tropical precipitation. Two models developed by other authors are modified according to the proposed formulation. The first is the intermediate atmospheric model of J. D. Neelin and N. Zeng, but with the horizontal connections between columns broken, rendering it a set of disconnected column models. The second is the column model of N. O. Rennó, K. A. Emanuel, and P. H. Stone. In the first model, the set of disconnected column models is run with a fixed temperature that is uniform in the Tropics, and insolation, SST, and surface wind speed taken from a control run of the original model. The column models produce a climatological precipitation field that is grossly similar to that of the control run, despite that the circulation implied by the column models is not required to conserve mass. The addition of horizontal moisture advection by the wind from the control run substantially improves the simulation in dry regions. In the second model the sensitivity of the modeled steady-state precipitation and relative humidity to varying SST and wind speed is examined. The transition from shallow to deep convection is simulated in a `Lagrangian' calculation in which the column model is subjected to an SST that increases in time. In this simulation, the onset of deep convection is delayed to a higher SST than in the steady-state case, due to the effect of horizontal moisture advection (viewed in a Lagrangian reference frame). In both of the

  15. Fuzzy Based composition Control of Distillation Column

    Directory of Open Access Journals (Sweden)



    Full Text Available This paper proposed a control scheme based on fuzzy logic for a methanol - water system of bubble cap distillation column. Fuzzy rule base and Inference System of fuzzy (FIS is planned to regulatethe reflux ratio (manipulated variable to obtain the preferred product composition (methanol for a distillation column. Comparisons are made with conventional controller and the results confirmed the potentials of the proposed strategy of fuzzy control.

  16. Nonlinear control of high purity distillation columns


    Groebel, Markus; Allgöwer, Frank; Storz, Markus; Gilles, Ernst Dieter


    Two simple models of distillation columns are studied to investigate their suitability for the practical use with exact I/O-linearization. An extension of exact I/O-linearization, the asymptotically exact I/O-linearization is applied to the control of a high purity distillation column, using one of these models to derive the static state feedback law. Simulation studies demonstrate the advantage of asymptotically exact I/O-linearization versus classical exact I/O-linearization techniques. Exp...

  17. The Dissipative Column: A New Hysteretic Damper


    Bruno Palazzo; Paolo Castaldo; Ivana Marino


    A new replaceable hysteretic damper to better control seismic building damage, consisting of two or more adjacent steel vertical elements connected to each other with continuous mild/low strength steel shear links, is proposed and investigated in this paper. New Dampers, called Dissipative Columns (DC), continuously linked with X-shaped steel plates, provide additional stiffness and damping to a lateral system by using a basic and minimally invasive construction element: the column. Working i...

  18. Transfer of pharmacopoeial liquid chromatography reversedphase methods for determination of related compounds in diclofenac sodium and metamizole sodium from conventional to core-shell column

    Directory of Open Access Journals (Sweden)

    Katerina Brezovska


    Full Text Available Core-shell silica particles were developed as a new material for chromatographic stationary phases in order to provide fast and high efficiency separations of small and large molecules and complex samples, at pressures compatible with conventional HPLC equipment. The aim of our work was to show the applicability of the HPLC columns based on a core-shell technology for determination of related substances in diclofenac sodium and in metamizole sodium using the methods described in the corresponding monographs of the European pharmacopoeia. The obtained results have shown that the proposed methods can be successfully transferred on core shell column, with suitable adjustment of injection volume and flow rate. The advantage of using core-shell column is fast and highly efficient separation on conventional HPLC equipment with increased sensitivity of the method and high throughput of the analysis, providing enhanced lab productivity and reduced costs.

  19. The handedness of historiated spiral columns. (United States)

    Couzin, Robert


    Trajan's Column in Rome (AD 113) was the model for a modest number of other spiral columns decorated with figural, narrative imagery from antiquity to the present day. Most of these wind upwards to the right, often with a congruent spiral staircase within. A brief introductory consideration of antique screw direction in mechanical devices and fluted columns suggests that the former may have been affected by the handedness of designers and the latter by a preference for symmetry. However, for the historiated columns that are the main focus of this article, the determining factor was likely script direction. The manner in which this operated is considered, as well as competing mechanisms that might explain exceptions. A related phenomenon is the reversal of the spiral in a non-trivial number of reproductions of the antique columns, from Roman coinage to Renaissance and baroque drawings and engravings. Finally, the consistent inattention in academic literature to the spiral direction of historiated columns and the repeated publication of erroneous earlier reproductions warrants further consideration.

  20. Similarity analyses of chromatographic herbal fingerprints: A review

    Energy Technology Data Exchange (ETDEWEB)

    Goodarzi, Mohammad [Department of Analytical Chemistry and Pharmaceutical Technology, Center for Pharmaceutical Research, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels (Belgium); Russell, Paul J. [Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ (United Kingdom); Vander Heyden, Yvan, E-mail: [Department of Analytical Chemistry and Pharmaceutical Technology, Center for Pharmaceutical Research, Vrije Universiteit Brussel, Laarbeeklaan 103, B-1090 Brussels (Belgium)


    Graphical abstract: -- Highlights: •Similarity analyses of herbal fingerprints are reviewed. •Different (dis)similarity approaches are discussed. •(Dis)similarity-metrics and exploratory-analysis approaches are illustrated. •Correlation and distance-based measures are overviewed. •Similarity analyses illustrated by several case studies. -- Abstract: Herbal medicines are becoming again more popular in the developed countries because being “natural” and people thus often assume that they are inherently safe. Herbs have also been used worldwide for many centuries in the traditional medicines. The concern of their safety and efficacy has grown since increasing western interest. Herbal materials and their extracts are very complex, often including hundreds of compounds. A thorough understanding of their chemical composition is essential for conducting a safety risk assessment. However, herbal material can show considerable variability. The chemical constituents and their amounts in a herb can be different, due to growing conditions, such as climate and soil, the drying process, the harvest season, etc. Among the analytical methods, chromatographic fingerprinting has been recommended as a potential and reliable methodology for the identification and quality control of herbal medicines. Identification is needed to avoid fraud and adulteration. Currently, analyzing chromatographic herbal fingerprint data sets has become one of the most applied tools in quality assessment of herbal materials. Mostly, the entire chromatographic profiles are used to identify or to evaluate the quality of the herbs investigated. Occasionally only a limited number of compounds are considered. One approach to the safety risk assessment is to determine whether the herbal material is substantially equivalent to that which is either readily consumed in the diet, has a history of application or has earlier been commercialized i.e. to what is considered as reference material. In order

  1. A novel two-dimensional liquid chromatographic system for the online toxicity prediction of pharmaceuticals and related substances

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian; Xu, Li [Tongji School of Pharmacy, Huazhong University of Science and Technology, Wuhan 430030 (China); Shi, Zhi-guo, E-mail: [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Hu, Min [Hubei Instrument for Food and Drug Control, Wuhan (China)


    Highlights: • A novel two-dimensional liquid chromatographic system was developed. • The 1st dimension was ODS to separate components in the sample. • The 2nd dimension was biopartitioning micellar chromatography to predict toxicity. • The system was used to screen toxicity of pharmaceuticals and related substances. • It was promising for fast online toxicity screening of complex sample in one step. - Abstract: In this study, a novel two-dimensional liquid chromatographic (2D-LC) system was developed for simultaneous separation and toxicity prediction of pharmaceutical and its related substances. A conventional ODS column was used on the 1st-D to separate the sample; while, bio-partitioning micellar chromatography served as the 2nd-D to predict toxicity of the components. The established system was tested for the toxicity of ibuprofen and its impurities with known toxicity. With only one injection, ibuprofen and its impurities were separated on the 1st-D; and LC50 values of individual impurity were obtained based on the quantitative retention–activity relationships, which agreed well with the reported data. Furthermore, LC50 values of photolysis transformation products (TPs) of carprofen, ketoprofen and diclofenac acid (as unknown compounds) were screened in this 2D-LC system, which could be an indicator of the toxicity of these TPs and was meaningful for the environmental monitoring and drinking water treatment. The established 2D-LC system was cost-effective, time-saving and reliable, and was promising for fast online screening of toxicity of known and unknown analytes in the complex sample in a single step. It may find applications in environment, pharmaceutical and food, etc.

  2. Practical Implication of Chromatographic Method for Estimation of Aceclofenac and Pregabalin in Bulk and Pharmaceutical Dosage Forms

    Directory of Open Access Journals (Sweden)

    Hitendrakumar D. Gelani


    Full Text Available Background. Aceclofenac and Pregabalin in combination significantly reduce pain as compared to individual drug in chronic low back pain. Literature reveals that all the reported spectrophotometric methods either need tedious extraction procedures, do not offer high sensitivity, use nonspecific reagent, or recommend the measurement of absorbance in the near UV region where interference most probably occurs that does not offer suitable linearity range. Result. A selective, sensitive, accurate, and precise, high performance liquid chromatographic method with UV detector analysis of Aceclofenac and Pregabalin was investigated. Good chromatographic separation was achieved using an ODS-BP hypersil C18 column (250 mm × 4.6 mm, i.d., 5 μm and a mobile phase consisting of 0.05 M phosphate buffer (KH2PO4 (pH 6.0 : methanol (60 : 40, v/v at a flow rate 1 mL/min. The ultraviolet detector was set at wavelength 218 nm. Retention time for Aceclofenac and Pregabalin was found to be 3.220 and 5.910 min, respectively. Rectilinear relationship with good regression coefficients 0.999 and 0.999 was found over the concentration ranges of 5–25 μg/mL and 3.75–18.75 μg/mL for ACF and PGB, respectively, with detection limits 0.64 and 0.35 μg/mL and quantitation limits 1.95 and 1.06 μg/mL. Conclusion. The mean percentage recoveries were in the range of 98.45–100.08 and 99.69–100.48 for ACF and PGB, respectively. The developed method was successfully applied to the analysis of the drugs in their commercial tablets.

  3. Liquid chromatographic determination of sitagliptin either alone or in ternary mixture with metformin and sitagliptin degradation product. (United States)

    El-Bagary, Ramzia I; Elkady, Ehab F; Ayoub, Bassam M


    Two reversed-phase liquid chromatographic (RP-LC) methods have been developed for the determination of sitagliptin phosphate monohydrate (STG). The first method comprised the determination of STG alone in bulk and plasma; and in its pharmaceutical preparation. This method was based on isocratic elution of STG using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (7.8)-acetonitrile (70:30, v/v) at a flow rate of 1 mL min(-1) with flourometric detection. The flourometric detector was operated at 267 nm for excitation and 575 nm for emission. In the second method, the simultaneous determination of STG and metformin (MET) in the presence of sitagliptin alkaline degradation product (SDP) has been developed. In this method, the ternary mixture of STG, MET and SDP was separated using a mobile phase consisting of potassium dihydrogen phosphate buffer pH (4.6)-acetonitrile-methanol (30:50:20, v/v/v) at a flow rate of 1 mL min(-1) with UV detection at 220 nm. Chromatographic separation in the two methods was achieved on a Symmetry(®) Waters C18 column (150 mm×4.6 mm, 5 μm). Linearity, accuracy and precision were found to be acceptable over the concentration ranges of 0.25-200 μg mL(-1) for STG with the first method and 5-160 μg mL(-1), 25-800 μg mL(-1) for STG and MET, respectively with the second method. The optimized methods were validated and proved to be specific, robust and accurate for the quality control of the cited drugs in pharmaceutical preparations.

  4. Validation of a micellar liquid chromatographic method for determination of caffeine and non-steroidal anti-inflammatories. (United States)

    El Sherbiny, Dina; Wahba, Mary E K


    An accurate, simple, sensitive and selective micellar liquid chromatographic method has been developed for the simultaneous determination of caffeine (CAF) and two non-steroidal anti-inflammatory drugs, namely ibuprofen (IBU) and ketoprofen (KET). The chemometric approach was applied to the optimization of separation of the studied drugs. To optimize their separation, the effect of six experimental parameters on retention was investigated by means of multivariate analysis. Separation was conducted using an ODS C18 (150 × 4.6 mm i.d.) stainless steel column at ambient temperature with UV detection at 260 nm. A mobile phase composed of 40 mM sodium dodecyl sulphate (SDS), 10% 1-propanol and 0.3% tri-ethylamine in 0.02 M phosphoric acid adjusted to pH 3 has been used at a flow rate of 1 mL/min. Regression models were characterized by both descriptive and predictive ability (R(2) ≥ 97.9% and R(cv)(2) ≥ 96.2%) and allowed the chromatographic separation of the drugs with a good resolution and a total analysis time within 15 min. The calibration curves were rectilinear over the concentration ranges of 2.0-25.0, 1.5-15.0 and 1.0-10.0 µg/mL for IBU, KET and CAF, respectively, with detection limits of 1.2, 1.0 and 0.6 µg/mL, and quantification limits of 1.6, 1.2 and 0.8 µg/mL, respectively. The results obtained were in good agreement with those obtained by the comparison method.

  5. New liquid chromatographic-chemometric approach for the determination of sunset yellow and tartrazine in commercial preparation. (United States)

    Dinç, Erdal; Aktaş, A Hakan; Ustündağ, Ozgür


    A new liquid chromatographic (LC)-chemometric approach was developed for the determination of sunset yellow (SUN) and tartrazine (TAR) in commercial preparations. This approach uses LC and chemometric calibration methods, i.e., classical least-squares (CLS), principal component regression (PCR), and partial-least squares (PLS), simultaneously. The combined LC-chemometric approaches, denoted as LC-CLS, LC-PCR, and LC-PLS, are based on photodiode array (PDA) detection at multiple wavelengths. Optimum chromatographic separation of SUN and TAR with allura red as the internal standard (IS) was obtained by using a Waters Symmetry C18 column, 5 microm, 4.6 x 250 mm, and 0.2 M acetate buffer (pH 5)-acetonitrile-methano-bidistilled water (55 + 20 + 15 + 10, v/v) as the mobile phase at a flow rate of 1.9 mL/min. The LC data sets consisting of the ratios of analyte peak areas to the IS peak area were obtained by using PDA detection at 5 wavelengths (465, 470, 475, 480, and 485 nm). LC-chemometric calibrations for SUN and TAR were separately constructed by using the relationship between the peak-area ratio and the training sets for each colorant. LC-chemometric approaches were tested for different synthetic mixtures containing SUN and TAR in the presence of the IS. These LC-chemometric calibrations were applied to a commercial preparation of the 2 colorants. The experimental results of the LC-chemometric approaches were compared with those obtained by a developed classical LC method using single-wavelength detection.

  6. Studies and research concerning BNFP pilot-scale pulsed columns: column profile and holdup studies

    Energy Technology Data Exchange (ETDEWEB)

    Cermak, A. F.


    Experimental studies were conducted on pilot-scaled pulsed columns for the purpose of obtaining data for verification of contactor computer programs. This work is in support of safeguards programs related to determination of near real-time inventories in pulsed columns. Holdup tests were performed resulting in the derivation of an empirical equation for estimation of the dispersed phase holdup in a column. Uranium solvent extraction mass-transfer tests were conducted in which all four process cycles were simulated under coprocessing flowsheet conditions. Extensive data were obtained during these tests on uranium profiles and inventories within the columns. Transient profile data were also determined between selected runs under the tested operating conditions. No concentration peaks could be observed during the transient period. Based on the extensive inventory data taken, empirical equations were developed for relating uranium inventory in a column to the test parameters. These equations were found useful for predicting and estimating the column inventory under the known run conditions.

  7. Accessing reaction rate constants in on-column reaction chromatography: an extended unified equation for reaction educts and products with different response factors. (United States)

    Trapp, Oliver; Bremer, Sabrina; Weber, Sven K


    An extension of the unified equation of chromatography to directly access reaction rate constants k(1) of first-order reaction in on-column chromatography is presented. This extended equation reflects different response factors in the detection of the reaction educt and product which arise from structural changes by elimination or addition, e.g., under pseudo-first-order reaction conditions. The reaction rate constants k(1) and Gibbs activation energies DeltaG(double dagger) of first-order reactions taking place in a chromatographic system can be directly calculated from the chromatographic parameters, i.e., retention times of the educt E and product P (t(R)(A) and t(R)(B)), peak widths at half height (w(A) and w(B)), the relative plateau height (h(p)) of the conversion profile, and the individual response factors f(A) and f(B). The evaluation of on-column reaction gas chromatographic experiments is exemplified by the evaluation of elution profiles obtained by ring-closing metathesis reaction of N,N-diallytrifluoroacetamide in presence of Grubbs second-generation catalyst, dissolved in polydimethylsiloxane (GE SE 30).

  8. Silica-based monolithic column with evaporative light scattering detector for HPLC analysis of bacosides and apigenin in Bacopa monnieri. (United States)

    Bhandari, Pamita; Kumar, Neeraj; Singh, Bikram; Singh, Virendra; Kaur, Inderjeet


    A high performance liquid chromatographic method using a silica-based monolithic column coupled with evaporative light scattering detector (HPLC-ELSD) was developed and validated for simultaneous quantification of bacosides (bacoside A, bacopaside I, bacoside A(3), bacopaside II, bacopaside X, bacopasaponin C) and apigenin in Bacopa monnieri. The chromatographic resolution was achieved on a Chromolith RP-18 (100x4.6 mm) column with acetonitrile/water (30:70) as mobile phase in isocratic elution at a flow rate of 0.7 mL/min. The drift tube temperature of the ELSD was set to 95 degrees C, and the nitrogen flow rate was 2.0 SLM (standard liter per minute). The calibration curves revealed a good linear relationship (r(2) > 0.9988) within the test ranges. The detection limits (S/N = 3) and the quantification limits (S/N = 10) for the compounds were in the range of 0.54-6.06 and 1.61-18.78 microg/mL, respectively. Satisfactory average recovery was observed in the range of 95.8-99.0%. The method showed good reproducibility for the quantification of these compounds in B. monnieri with intra- and inter-day precision of less than 0.69 and 0.67%, respectively. The validated method was successfully applied to quantify analytes in nine accessions of B. monnieri and thus provides a new basis for overall quality assessment of B. monnieri.

  9. Developing Inquiry-Based Labs Using Micro-Column Chromatography (United States)

    Barden-Gabbei, Laura M.; Moffitt, Deborah L.


    Chromatography is a process by which mixtures can be separated or substances can be purified. Biological and chemical laboratories use many different types of chromatographic processes. For example, the pharmaceutical industry uses chromatographic techniques to purify drugs, medical labs use them to identify blood components such as cholesterol,…

  10. Multiple chromatographic fingerprinting and its application to the quality control of herbal medicines

    Energy Technology Data Exchange (ETDEWEB)

    Fan Xiaohui [Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310027 (China); Cheng Yiyu [Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310027 (China)]. E-mail:; Ye Zhengliang [Pharmaceutical Informatics Institute, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310027 (China); Lin Ruichao [National Institute for the Control of Pharmaceutical and Biological Products, Beijing 100050 (China); Qian Zhongzhi [Committee of Chinese Pharmacopoeia, Beijing 100061 (China)


    Recently, chromatographic fingerprinting has become one of the most powerful approaches to quality control of herbal medicines. However, the performance of reported chromatographic fingerprinting constructed by single chromatogram sometimes turns out to be inadequate for complex herbal medicines, such as multi-herb botanical drug products. In this study, multiple chromatographic fingerprinting, which consists of more than one chromatographic fingerprint and represents the whole characteristics of chemical constitutions of the complex medicine, is proposed as a potential strategy in this complicated case. As a typical example, a binary chromatographic fingerprinting of 'Danshen Dropping Pill' (DSDP), the best-sold traditional Chinese medicine in China, was developed. First, two HPLC fingerprints that, respectively, represent chemical characteristics of depsides and saponins of DSDP were developed, which were used to construct binary chromatographic fingerprints of DSDP. Moreover, the authentication and validation of the binary fingerprints were performed. Then, a data-level information fusion method was employed to capture the chemical information encoded in two chromatographic fingerprints. Based on the fusion results, the lot-to-lot consistency and frauds can be determined either using similarity measure or by chemometrics approach. The application of binary chromatographic fingerprinting to consistency assessment and frauds detection of DSDP clearly demonstrated that the proposed method was a powerful approach to quality control of complex herbal medicines.

  11. Derivatization in gas chromatographic determination of phenol and aniline traces in aqueous media (United States)

    Gruzdev, I. V.; Zenkevich, I. G.; Kondratenok, B. M.


    Substituted anilines and phenols are the most common hydrophilic organic environmental toxicants. The principles of gas chromatographic determination of trace amounts of these compounds in aqueous media at concentrations extractive preconcentration and selective chromatographic detection. Among the known reactions, this condition is best met by electrophilic halogenation of compounds at the aromatic moiety. The bibliography includes 177 references.

  12. Structural Decoupling and Disturbance Rejection in a Distillation Column

    DEFF Research Database (Denmark)

    Bahar, Mehrdad; Jantzen, Jan; Commault, C.;


    Introduction, distillation column model, input-output decoupling, disturbance rejection, concluding remarks, references.......Introduction, distillation column model, input-output decoupling, disturbance rejection, concluding remarks, references....

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

  14. Chromatographic separation of radioactive noble gases from xenon

    CERN Document Server

    Akerib, D S; Bai, X; Bailey, A J; Balajthy, J; Beltrame, P; Bernard, E P; Bernstein, A; Biesiadzinski, T P; Boulton, E M; Bramante, R; Cahn, S B; Carmona-Benitez, M C; Chan, C; Chiller, A A; Chiller, C; Coffey, T; Currie, A; Cutter, J E; Davison, T J R; Dobi, A; Dobson, J E Y; Druszkiewicz, E; Edwards, B N; Faham, C H; Fiorucci, S; Gaitskell, R J; Gehman, V M; Ghag, C; Gibson, K R; Gilchriese, M G D; Hall, C R; Hanhardt, M; Haselschwardt, S J; Hertel, S A; Hogan, D P; Horn, M; Huang, D Q; Ignarra, C M; Ihm, M; Jacobsen, R G; Ji, W; Kamdin, K; Kazkaz, K; Khaitan, D; Knoche, R; Larsen, N A; Lee, C; Lenardo, B G; Lesko, K T; Lindote, A; Lopes, M I; Manalaysay, A; Mannino, R L; Marzioni, M F; McKinsey, D N; Mei, D -M; Mock, J; Moongweluwan, M; Morad, J A; Murphy, A St J; Nehrkorn, C; Nelson, H N; Neves, F; O'Sullivan, K; Oliver-Mallory, K C; Palladino, K J; Pease, E K; Pech, K; Phelps, P; Reichhart, L; Rhyne, C; Shaw, S; Shutt, T A; Silva, C; Solovov, V N; Sorensen, P; Stephenson, S; Sumner, T J; Szydagis, M; Taylor, D J; Taylor, W; Tennyson, B P; Terman, P A; Tiedt, D R; To, W H; Tripathi, M; Tvrznikova, L; Uvarov, S; Verbus, J R; Webb, R C; White, J T; Whitis, T J; Witherell, M S; Wolfs, F L H; Yazdani, K; Young, S K; Zhang, C


    The Large Underground Xenon (LUX) experiment operates at the Sanford Underground Research Facility to detect nuclear recoils from the hypothetical Weakly Interacting Massive Particles (WIMPs) on a liquid xenon target. Liquid xenon typically contains trace amounts of the noble radioactive isotopes $^{85}$Kr and $^{39}$Ar that are not removed by the {\\em in situ} gas purification system. The decays of these isotopes at concentrations typical of research-grade xenon would be a dominant background for a WIMP search exmperiment. To remove these impurities from the liquid xenon, a chromatographic separation system based on adsorption on activated charcoal was built. 400\\,kg of xenon was processed, reducing the average concentration of krypton from 130\\,ppb to 3.5\\,ppt as measured by a cold-trap assisted mass spectroscopy system. A 50 kg batch spiked to 0.001 g/g of krypton was processed twice and reduced to an upper limit of 0.2 ppt.

  15. Extraction, chromatographic and mass spectrometric methods for lipid analysis. (United States)

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


    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.

  16. Measurement uncertainty of liquid chromatographic analyses visualized by Ishikawa diagrams. (United States)

    Meyer, Veronika R


    Ishikawa, or cause-and-effect diagrams, help to visualize the parameters that influence a chromatographic analysis. Therefore, they facilitate the set up of the uncertainty budget of the analysis, which can then be expressed in mathematical form. If the uncertainty is calculated as the Gaussian sum of all uncertainty parameters, it is necessary to quantitate them all, a task that is usually not practical. The other possible approach is to use the intermediate precision as a base for the uncertainty calculation. In this case, it is at least necessary to consider the uncertainty of the purity of the reference material in addition to the precision data. The Ishikawa diagram is then very simple, and so is the uncertainty calculation. This advantage is given by the loss of information about the parameters that influence the measurement uncertainty.

  17. Fatty acids determination in Bronte pistachios by gas chromatographic method. (United States)

    Pantano, Licia; Lo Cascio, Giovanni; Alongi, Angelina; Cammilleri, Gaetano; Vella, Antonio; Macaluso, Andrea; Cicero, Nicola; Migliazzo, Aldo; Ferrantelli, Vincenzo


    A gas chromatographic with flame ionization detector (GC-MS FID) method for the identification and quantification of fatty acids based on the extraction of lipids and derivatisation of free acids to form methyl esters was developed and validated. The proposed method was evaluated to a number of standard FAs, and Bronte pistachios samples were used for that purpose and to demonstrate the applicability of the proposed method. In this regard, repeatability, mean and standard deviation of the analytical procedure were calculated. The results obtained have demonstrated oleic acid as the main component of Bronte pistachios (72.2%) followed by linoleic acid (13.4%) and showed some differences in composition with respect to Tunisian, Turkish and Iranian pistachios.

  18. Model-based design of peptide chromatographic purification processes. (United States)

    Gétaz, David; Stroehlein, Guido; Butté, Alessandro; Morbidelli, Massimo


    In this work we present a general procedure for the model-based optimization of a polypeptide crude mixture purification process through its application to a case of industrial relevance. This is done to show how much modeling can be beneficial to optimize complex chromatographic processes in the industrial environment. The target peptide elution profile was modeled with a two sites adsorption equilibrium isotherm exhibiting two inflection points. The variation of the isotherm parameters with the modifier concentration was accounted for. The adsorption isotherm parameters of the target peptide were obtained by the inverse method. The elution of the impurities was approximated by lumping them into pseudo-impurities and by regressing their adsorption isotherm parameters directly as a function of the corresponding parameters of the target peptide. After model calibration and validation by comparison with suitable experimental data, Pareto optimizations of the process were carried out so as to select the optimal batch process.

  19. Liquid Chromatographic Method for Determination of Nisoldipine from Pharmaceutical Samples

    Directory of Open Access Journals (Sweden)

    Amit Gupta


    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.

  20. A Duffing oscillator algorithm to detect the weak chromatographic signal. (United States)

    Zhang, Wei; Xiang, Bing-Ren


    Based on the Duffing equation, a Duffing oscillator algorithm (DOA) to improve the signal-to-noise ratio (SNR) was presented. By simulated and experimental data sets, it was proven that the signal-to-noise ratio (SNR) of the weak signal could be greatly enhanced by this method. Using signal enhancement by DOA, this method extends the SNR of low concentrations of methylbenzene from 2.662 to 29.90 and the method can be used for quantitative analysis of methylbenzene, which are lower than detection limit of an analytical system. The Duffing oscillator algorithm (DOA) might be a promising tool to extend instrumental linear range and to improve the accuracy of trace analysis. The research enlarged the application scope of Duffing equation to chromatographic signal processing.

  1. Luminescent determination of quinolones in milk samples by liquid chromatography/post-column derivatization with terbium oxide nanoparticles. (United States)

    Yánez-Jácome, G S; Aguilar-Caballos, M P; Gómez-Hens, A


    The usefulness of terbium oxide nanoparticles (Tb4O7NPs) as post-column derivatizing reagent for the liquid chromatographic determination of residues of quinolone antibiotics in milk samples has been studied. Seven quinolones of veterinary use have been chosen as model analytes to develop this method. The derivatization step is based on the formation of luminescent chelates of quinolones with Tb4O7NPs, which are monitored at λex=340nm and λem=545nm. Another relevant feature of the method is that the use of a 10-cm column and a ternary mixture of methanol, acetonitrile and acetic acid as mobile phase in gradient elution mode allow the chromatographic separation of the quinolones in about 13min, whereas previously described chromatographic methods require about 20min. The dynamic ranges of the calibration graphs and limits of detection are, respectively: 65-900ngmL(-1) and 35ngmL(-1) for marbofloxacin, 7.2-900ngmL(-1) and 2.5ngmL(-1) for ciprofloxacin, 6-900ngmL(-1) and 2ngmL(-1) for danofloxacin, 50-900ngmL(-1) and 20ngmL(-1) for enrofloxacin, 35-900ngmL(-1) and 12ngmL(-1) for sarafloxacin, 5-900ngmL(-1) and 2ngmL(-1) for oxolinic acid, and 7-900ngmL(-1) and 2.5ngmL(-1) for flumequine. The precision, established at two concentration levels of each analyte and expressed as the percentage of the relative standard deviation is in the range of 1.9-8.1% using standards, and of 3.4-10.7% in the presence of milk samples. The method has been satisfactorily applied to the analysis of skimmed, semi-skimmed and whole milk samples, with recoveries ranging from 89.0 to 106.5%.

  2. Column flotation of bitumen at Fort Hills

    Energy Technology Data Exchange (ETDEWEB)

    Lizama, H.M. [Teck Cominco, Vancouver, BC (Canada); Romero, D. [UTS Energy Corp., Calgary, AB (Canada); Armour, M. [Petro-Canada, Calgary, AB (Canada)


    Flotation columns are used by mineral processors to separate mineral species. The separation is based on the premise that different mineral particles have different surface hydrophobicities. There are 2 carrier phases, notably air bubbles moving up and aqueous pulp moving down. Hydrophobic particles predominantly adhere to rising air bubbles and form a froth, while hydrophilic particles remain in aqueous suspension and flow down and out the bottom of the column. This paper described a demonstration plant near Fort McMurray where bitumen extraction was tested. The plant included 2 columns for bitumen flotation. Oil sands material was passed through a roll sizer and fed to a countercurrent drum separator, where it was mixed with water at 75 degrees C. Column data from the demonstration plant provided the opportunity to examine the separation behaviour during flotation of bitumen. The bitumen grade was described only in terms of bitumen content and solids content in order to simplify the interpretation of the bitumen flotation data. Bitumen/solids separation in the first column was successful at 50 to 60 degrees C, with feeds having bitumen grades between 1 and 19 per cent, and where the solids had about 60 per cent fines. Bitumen/solids separation did not occur in the second column at 50 to 60 degrees C, with feeds having bitumen grades between 8 and 63 per cent, and where the solids had about 90 per cent fines. The lack of separation was probably due to high solids entrainment in the flotation froth. It was concluded that bitumen column flotation data can be analyzed and interpreted by adopting mineral processing principles. Bitumen/solids separation can be evaluated and predicted by plotting solids recovery as a function of bitumen recovery. 7 refs., 1 tab., 6 figs.

  3. Ion-exclusion chromatography with the direct UV detection of non-absorbing inorganic cations using an anion-exchange conversion column in the iodide-form. (United States)

    Mori, Masanobu; Itabashi, Hideyuki; Ikedo, Mikaru; Tanaka, Kazuhiko


    An ion-exclusion chromatographic method for the direct UV detection of non-absorbing inorganic cations such as sodium (Na(+)), ammonium (NH(4)(+)) and hydrazine (N(2)H(5)(+)) ions was developed by connecting an anion-exchange column in the I(-)-form after the separation column. For example, NH(4)(+) is converted to a UV-absorbing molecule, NH(4)I, by the anion-exchange column in the I(-)-form after the ion-exclusion separation on anion-exchange column in the OH(-)-form with water eluent. As a result, the direct UV detection of Na(+), NH(4)(+) and N(2)H(5)(+) could be successfully obtained as well as the well-resolved separation. The calibration graphs of the analyte cations detected with UV at 230nm were linear in the range of 0.001-5.0mM. The detection limits at S/N=3 of the cations were below 0.1muM. This method was applied to real water analysis, the determination of NH(4)(+) in river and rain waters, or that of N(2)H(5)(+) in boiler water, with the satisfactory results. This could be applied also to low- or non-absorbing anions such as fluoride or hydrogencarbonate ions by the combination of a weakly acidic cation-exchange resin in the H(+)-form as the separation column and the anion-exchange conversion column.

  4. Comparison of sulfuric acid treatment and multi-layer silica gel column chromatography in cleanup methods for determination of PCDDs, PCDFs and dioxin-like PCBs in foods. (United States)

    Amakura, Yoshiaki; Tsutsumi, Tomoaki; Sasaki, Kumiko; Toyoda, Masatake; Maitani, Tamio


    Two typical cleanup methods, sulfuric acid treatment and multi-layer silica gel column chromatography, for the determination of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) in seventeen food samples were examined and compared. Vegetables, fruits, cereals, fish, meat and dairy foods were extracted by conventional methods (shaking with acetone/n-hexane or with n-hexane after alkaline treatment). The extracts were cleaned up by sulfuric acid treatment or multi-layer silica gel column chromatography, followed by several column chromatographic steps. Of the samples treated, the vegetable, fruit and cereal samples could be directly applied to the multi-layer silica gel column after extraction. However, the samples containing fats and oils such as fish, meat and dairy foods needed to be treated several times with concentrated sulfuric acid before multi-layer column chromatography, because these samples plugged the column with oily residues. Both cleanup methods gave similar values of isomeric concentrations and showed similar efficiency of purification, and the recoveries ranged from 40 to 120%. These results are considered to provide useful data for the efficient analysis of dioxins in foods which have wide-ranging compositions.

  5. Post Column Derivatization Using Reaction Flow High Performance Liquid Chromatography Columns. (United States)

    Jones, Andrew; Pravadali-Cekic, Sercan; Hua, Stanley; Kocic, Danijela; Camenzuli, Michelle; Dennis, Gary; Shalliker, Andrew


    A protocol for the use of reaction flow high performance liquid chromatography columns for methods employing post column derivatization (PCD) is presented. A major difficulty in adapting PCD to modern HPLC systems and columns is the need for large volume reaction coils that enable reagent mixing and then the derivatization reaction to take place. This large post column dead volume leads to band broadening, which results in a loss of observed separation efficiency and indeed detection in sensitivity. In reaction flow post column derivatization (RF-PCD) the derivatization reagent(s) are pumped against the flow of mobile phase into either one or two of the outer ports of the reaction flow column where it is mixed with column effluent inside a frit housed within the column end fitting. This technique allows for more efficient mixing of the column effluent and derivatization reagent(s) meaning that the volume of the reaction loops can be minimized or even eliminated altogether. It has been found that RF-PCD methods perform better than conventional PCD methods in terms of observed separation efficiency and signal to noise ratio. A further advantage of RF-PCD techniques is the ability to monitor effluent coming from the central port in its underivatized state. RF-PCD has currently been trialed on a relatively small range of post column reactions, however, there is currently no reason to suggest that RF-PCD could not be adapted to any existing one or two component (as long as both reagents are added at the same time) post column derivatization reaction.

  6. Instrument contributions to resolution and sensitivity in ultra high performance liquid chromatography using small bore columns: comparison of diode array and triple quadrupole mass spectrometry detection. (United States)

    Buckenmaier, Stephan; Miller, Christine A; van de Goor, Tom; Dittmann, Monika M


    UHPLC with DAD-UV detection or in combination with mass spectrometry (MS) has proven to be a robust and widely applicable platform for high sensitivity analyses of many types of chemical compounds. The majority of users employ narrow bore columns with 2.1mm internal diameter (ID) typically exhibiting very high efficiencies (>200,000 plates/m). This ultimately sets stringent demands upon the chromatographic system as the separation efficiency can be compromised by external contributions to dispersion caused by connection capillaries, auto-sampler and/or the detection device. Sample limited applications often use reduced column diameters down to capillary- or even nano-column format. Capillary (ID≤0.5mm) or small-bore columns (ID≤1mm) can be a good compromise between system robustness and enhanced sensitivity. Yet in this case, extra-column dispersion gains additional importance due to reduced peak volumes. To design an optimized system configuration for specific column dimensions and applications it is crucial to understand the dispersion contributions of individual extra-column components. This was subject to many studies done within our group and by others. Here, we employed a fully optimized UHPLC/UV system to investigate the contribution to peak dispersion obtained from columns ranging from capillary to narrow bore (0.3, 0.5, 1, 2.1mm) using a set of small molecules that were analyzed in gradient mode. Further UV detection was replaced by a triple quadrupole (QQQ) MS in order to evaluate its contribution to band broadening. In this context the impact of column-ID upon MS sensitivity when interfaced with an Agilent Jet Stream source was investigated. Data obtained from our test suite of compounds shows mostly mass-sensitive behavior of this advanced electrospray technology.

  7. Optimisation and validation of ultra-high performance liquid chromatographic-tandem mass spectrometry method for qualitative and quantitative analysis of potato steroidal alkaloids. (United States)

    Hossain, Mohammad B; Rai, Dilip K; Brunton, Nigel P


    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. Liquid chromatographic-electrospray mass spectrometric determination (LC-ESI-MS) of phase II metabolites of flobufen in rat liver microsomes-Chiral discrimination. (United States)

    Babú, Yogeeta N; Nemec, Michal; Solich, Petr; Wsól, Vladimír


    Glucuronidation of the non-steroidal anti-inflammatory chiral drug flobufen and its major metabolite M17203 has been implicated as an important mechanism of flobufen elimination. To characterize flobufen metabolism by O-glucuronidation, new liquid chromatographic method (LC) coupled with ESI-MS was developed to detect the conjugates of flobufen and its metabolites formed in vitro in rat liver microsomes. Discovery DSC-18 LT cartridge columns were utilized for solid phase extraction (SPE) and Discovery C18 column (150 mm x 2.1 mm, 5 microm particle size) was used for LC separation. Chiral inversion of flobufen and its metabolites enantiomers was checked by special 1-allyl-(5R,8S,10R)-terguride column (150 mm x 4.6 mm). O-Glucuronidation of the S-enantiomer displayed a typical Michaelis-Menten kinetics, whereas the R-enantiomer exhibited a substrate inhibition type of kinetics. The study of glucuronidation of M17203 led to kinetics with sigmoidal characteristics.

  9. High-performance liquid chromatographic determination of clindamycin in human plasma or serum: application to the bioequivalency study of clindamycin phosphate injections. (United States)

    Liu, C M; Chen, Y K; Yang, T H; Hsieh, S Y; Hung, M H; Lin, E T


    This paper presents an assay of clindamycin phosphate injection in human plasma or serum. A 0.5-ml volume of plasma was used with the internal standard, propranolol. The sample was loaded onto a silica extraction column. The column was washed with deionized water and then eluted with methanol. The eluates were evaporated under nitrogen gas. The residue was reconstituted with the mobile phase and injected onto the high-performance liquid chromatographic system: a 5-micron, 25 cm X 4.6 mm I.D. ODS2 column was used with acetonitrile, tetrahydrofuran and 0.05 M phosphate buffer as the mobile phase and with ultraviolet detection at 204 nm. A limit of quantitation of 0.05 microgram/ml was found, with a coefficient of variation of 11.6% (n = 6). The linear range is between 0.05 and 20.00 micrograms/ml and gives a coefficient of determination (r2) or 0.9992. The method has been successfully applied to the bioavailability study of two commercial preparations of clindamycin phosphate injection (300 mg each) in twelve healthy adult male volunteers.

  10. Robust Matrix Completion with Corrupted Columns

    CERN Document Server

    Chen, Yudong; Caramanis, Constantine; Sanghavi, Sujay


    This paper considers the problem of matrix completion, when some number of the columns are arbitrarily corrupted, potentially by a malicious adversary. It is well-known that standard algorithms for matrix completion can return arbitrarily poor results, if even a single column is corrupted. What can be done if a large number, or even a constant fraction of columns are corrupted? In this paper, we study this very problem, and develop an efficient algorithm for its solution. Our results show that with a vanishing fraction of observed entries, it is nevertheless possible to succeed in performing matrix completion, even when the number of corrupted columns grows. When the number of corruptions is as high as a constant fraction of the total number of columns, we show that again exact matrix completion is possible, but in this case our algorithm requires many more -- a constant fraction -- of observations. One direct application comes from robust collaborative filtering. Here, some number of users are so-called mani...

  11. Three-dimensional topographic index applied to the prediction of acyclic C5-C8 alkenes Kováts retention indices on polydimethylsiloxane and squalane columns. (United States)

    Ren, Yueying; Liu, Huanxiang; Yao, Xiaojun; Liu, Mancang


    A novel approach is described for the prediction of gas chromatographic Kováts retention indices of 150 acyclic C5-C8 alkenes on two stationary phases (polydimethylsiloxane, PDMS, and squalane, SQ). The heuristic method was used to build multiple linear regression models using descriptors calculated by MODLESLAB software and CODESSA program. The resulting quantitative structure-retention relationship (QSRR) models were well-correlated, with predictive R2 values of 0.970 and 0.958 for retention indices on PDMS and SQ columns, respectively. 1Omegap, a three-dimensional (3D) topographic index, was found to play the most important role in the description of the chromatographic retention behavior of the alkenes in these two stationary phases. Moreover, this index could completely distinguish different isomers of alkene. Therefore, it can also be extended to distinguish different isomers of other compounds so that can well describe their quantitative structure-retention relationships.

  12. A rapid HPLC column switching method for sample preparation and determination of β-carotene in food supplements. (United States)

    Brabcová, Ivana; Hlaváčková, Markéta; Satínský, Dalibor; Solich, Petr


    A simple and automated HPLC column-switching method with rapid sample pretreatment has been developed for quantitative determination of β-carotene in food supplements. Commercially samples of food supplements were dissolved in chloroform with help of saponification with 1M solution of sodium hydroxide in ultrasound bath. A 20-min sample dissolution/extraction step was necessary before chromatography analysis to transfer β-carotene from solid state of food supplements preparations (capsules,tablets) to chloroform solution. Sample volume - 3μL of chloroform phase was directly injected into the HPLC system. Next on-line sample clean-up was achieved on the pretreatment precolumn Chromolith Guard Cartridge RP-18e (Merck), 10×4.6mm, with a washing mobile phase (methanol:water, 92:8, (v/v)) at a flow rate of 1.5mL/min. Valve switch to analytical column was set at 2.5min in a back-flush mode. After column switching to the analytical column Ascentis Express C-18, 30×4.6mm, particle size 2.7μm (Sigma Aldrich), the separation and determination of β-carotene in food supplements was performed using a mobile phase consisting of 100% methanol, column temperature at 60°C and flow rate 1.5mL/min. The detector was set at 450nm. Under the optimum chromatographic conditions standard calibration curve was measured with good linearity - correlation coefficient for β-carotene (r(2)=0.999014; n=6) between the peak areas and concentration of β-carotene 20-200μg/mL. Accuracy of the method defined as a mean recovery was in the range 96.66-102.40%. The intraday method precision was satisfactory at three concentration levels 20, 125 and 200μg/mL and relative standard deviations were in the range 0.90-1.02%. The chromatography method has shown high sample throughput during column-switching pretreatment process and analysis in one step in short time (6min) of the whole chromatographic analysis.

  13. Non-planar microfabricated gas chromatography column (United States)

    Lewis, Patrick R.; Wheeler, David R.


    A non-planar microfabricated gas chromatography column comprises a planar substrate having a plurality of through holes, a top lid and a bottom lid bonded to opposite surfaces of the planar substrate, and inlet and outlet ports for injection of a sample gas and elution of separated analytes. A plurality of such planar substrates can be aligned and stacked to provide a longer column length having a small footprint. Furthermore, two or more separate channels can enable multi-channel or multi-dimensional gas chromatography. The through holes preferably have a circular cross section and can be coated with a stationary phase material or packed with a porous packing material. Importantly, uniform stationary phase coatings can be obtained and band broadening can be minimized with the circular channels. A heating or cooling element can be disposed on at least one of the lids to enable temperature programming of the column.

  14. Methylmercury production in the marine water column (United States)

    Topping, G.; Davies, I. M.


    Although the biosynthesis of methylmercury in sediments is well established1, this is not necessarily the exclusive natural source of methylmercury entering the marine food chain, particularly commercial fish and shellfish species for human consumption. An examination of mercury levels in freshwater fish2, collected from a lake with a history of industrial mercury contamination, suggested that levels in fish are controlled in part by mercury in suspension and it followed that methylation should occur in the water column. Although methylmercury is present in seawater in coastal areas receiving discharges of waste containing either inorganic mercury3 or methylmercury4 there is no evidence that methylmercury is actually formed in the water column. We now present data which demonstrate that inorganic mercury can be methylated in the water column and we compare this production with that known to occur in marine sediments.

  15. Computational analysis of ozonation in bubble columns

    Energy Technology Data Exchange (ETDEWEB)

    Quinones-Bolanos, E. [Univ. of Guelph, School of Engineering, Guelph, Ontario (Canada)]|[Univ. de Cartagena, Facultad de Ciencias e Ingenieria, Cartagena de Indias (Colombia); Zhou, H.; Otten, L. [Univ. of Guelph, School of Engineering, Guelph, Ontario (Canada)]. E-mail:


    This paper presents a new computational ozonation model based on the principle of computational fluid dynamics along with the kinetics of ozone decay and microbial inactivation to predict the performance of ozone disinfection in fine bubble columns. The model can be represented using a mixture two-phase flow model to simulate the hydrodynamics of the water flow and using two transport equations to track the concentration profiles of ozone and microorganisms along the height of the column, respectively. The applicability of this model was then demonstrated by comparing the simulated ozone concentrations with experimental measurements obtained from a pilot scale fine bubble column. One distinct advantage of this approach is that it does not require the prerequisite assumptions such as plug flow condition, perfect mixing, tanks-in-series, uniform radial or longitudinal dispersion in predicting the performance of disinfection contactors without carrying out expensive and tedious tracer studies. (author)

  16. Neutron camera employing row and column summations (United States)

    Clonts, Lloyd G.; Diawara, Yacouba; Donahue, Jr, Cornelius; Montcalm, Christopher A.; Riedel, Richard A.; Visscher, Theodore


    For each photomultiplier tube in an Anger camera, an R.times.S array of preamplifiers is provided to detect electrons generated within the photomultiplier tube. The outputs of the preamplifiers are digitized to measure the magnitude of the signals from each preamplifier. For each photomultiplier tube, a corresponding summation circuitry including R row summation circuits and S column summation circuits numerically add the magnitudes of the signals from preamplifiers for each row and for each column to generate histograms. For a P.times.Q array of photomultiplier tubes, P.times.Q summation circuitries generate P.times.Q row histograms including R entries and P.times.Q column histograms including S entries. The total set of histograms include P.times.Q.times.(R+S) entries, which can be analyzed by a position calculation circuit to determine the locations of events (detection of a neutron).

  17. Preparation of a poly(3'-azido-3'-deoxythymidine-co-propargyl methacrylate-co-pentaerythritol triacrylate) monolithic column by in situ polymerization and a click reaction for capillary liquid chromatography of small molecules and proteins. (United States)

    Lin, Zian; Yu, Ruifang; Hu, Wenli; Zheng, Jiangnan; Tong, Ping; Zhao, Hongzhi; Cai, Zongwei


    Combining free radical polymerization with click chemistry via a copper-mediated azide/alkyne cycloaddition (CuAAC) reaction in a "one-pot" process, a facile approach was developed for the preparation of a poly(3'-azido-3'-deoxythymidine-co-propargyl methacrylate-co-pentaerythritol triacrylate) (AZT-co-PMA-co-PETA) monolithic column. The resulting poly(AZT-co-PMA-co-PETA) monolith showed a relatively homogeneous monolithic structure, good permeability and mechanical stability. Different ratios of monomers and porogens were used for optimizing the properties of a monolithic column. A series of alkylbenzenes, amides, anilines, and benzoic acids were used to evaluate the chromatographic properties of the polymer monolith in terms of hydrophobic, hydrophilic and cation-exchange interactions, and the results showed that the poly(AZT-co-PMA-co-PETA) monolith exhibited more flexible adjustment in chromatographic selectivity than that of the parent poly(PMA-co-PETA) and AZT-modified poly(PMA-co-PETA) monoliths. Column efficiencies for toluene, DMF, and formamide with 35,000-48,000 theoretical plates per m could be obtained at a linear velocity of 0.17 mm s(-1). The run-to-run, column-to-column, and batch-to-batch repeatabilities of the retention factors were less than 4.2%. In addition, the proposed monolith was also applied to efficient separation of sulfonamides, nucleobases and nucleosides, anesthetics and proteins for demonstrating its potential.

  18. Accelerating selected columns of the density matrix computations via approximate column selection

    CERN Document Server

    Damle, Anil; Ying, Lexing


    Localized representation of the Kohn-Sham subspace plays an important role in quantum chemistry and materials science. The recently developed selected columns of the density matrix (SCDM) method [J. Chem. Theory Comput. 11, 1463, 2015] is a simple and robust procedure for finding a localized representation of a set of Kohn-Sham orbitals from an insulating system. The SCDM method allows the direct construction of a well conditioned (or even orthonormal) and localized basis for the Kohn-Sham subspace. The SCDM procedure avoids the use of an optimization procedure and does not depend on any adjustable parameters. The most computationally expensive step of the SCDM method is a column pivoted QR factorization that identifies the important columns for constructing the localized basis set. In this paper, we develop a two stage approximate column selection strategy to find the important columns at much lower computational cost. We demonstrate the effectiveness of this process using a dissociation process of a BH$_{3}...

  19. Final Report, Distillation Column Flooding Predictor

    Energy Technology Data Exchange (ETDEWEB)

    George E. Dzyacky


    The Flooding Predictor is an advanced process control strategy comprising a patented pattern-recognition methodology that identifies pre-flood patterns discovered to precede flooding events in distillation columns. The grantee holds a U.S. patent on the modeling system. The technology was validated at the Separations Research Program, The University of Texas at Austin under a grant from the U. S. Department of Energy, Inventions & Innovation Program. Distillation tower flooding occurs at abnormally high vapor and/or liquid rates. The loss in tray efficiencies is attributed to unusual behavior of liquid inventories inside the column leading to conditions of flooding of the space in between trays with liquid. Depending on the severity of the flood condition, consequences range from off spec products to equipment damage and tower shutdown. This non-intrusive pattern recognition methodology, processes signal data obtained from existing column instrumentation. Once the pattern is identified empirically, it is modeled and coded into the plant's distributed control system. The control system is programmed to briefly "unload" the tower each time the pattern appears. The unloading takes the form of a momentary reduction in column severity, e.g., decrease bottom temperature, reflux or tower throughput. Unloading the tower briefly at the pre-flood state causes long-term column operation to become significantly more stable - allowing an increase in throughput and/or product purity. The technology provides a wide range of value between optimization and flooding. When a distillation column is not running at capacity, it should be run in such a way ("pushed") that optimal product purity is achieved. Additional benefits include low implementation and maintenance costs, and a high level of console operator acceptance. The previous commercial applications experienced 98% uptime over a four-year period. Further, the technology is unique in its ability to distinguish between

  20. Complex osteotomies vertebral column resection and decancellation. (United States)

    Obeid, Ibrahim; Bourghli, Anouar; Boissière, Louis; Vital, Jean-Marc; Barrey, Cédric


    Pedicle subtraction osteotomy (PSO) is nowadays widely used to treat sagittal imbalance. Some complex malalignment cases cannot be treated by a PSO, whereas the imbalance is coronal or mixed or the sagittal imbalance is major and cannot be treated by a single PSO. The aim of this article was to review these complex situations--coronal imbalance, mixed imbalance, two-level PSO, vertebral column resection, and vertebral column decancellation, and to focus on their specificities. It wills also to evoke the utility of navigation in these complex cases.