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Sample records for acid determination metodos

  1. Determination of the biodiesel acidity index by potentiometric titration by using different methods; Determinacao do indice de acidez de biodiesel por titulacao potenciometrica utilizando-se diferentes metodos

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    Goncalves, Mary Ane; Sobral, Sidney Pereira; Borges, Paulo Paschoal [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial (DIMCI/INMETRO), Duque de Caxias, RJ (Brazil). Diretoria de Metrologia Cientifica e Industrial], E-mail: magoncalves@inmetro.gov.br

    2009-07-01

    This work determined the index of the soybean/fat bio diesel through the potentiometric titration. Four different methods were used with variation of solvent and electrodes. The results were compared by F and t (Student) and it was verified that they were agreed in a 95% confidence interval.

  2. An analytical method for determination of mercury by cold vapor atomic absorption spectroscopy; Determinazione di mercurio. Metodo per spettrometria di assorbimento atomico a vapori freddi (CV-AAS)

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    Campanella, L. [Rome Univ. La Sapienza, Rome (Italy); Mastroianni, D.; Capri, S.; Pettine, M. [CNR, Rome (Italy). Ist. di Ricerca sulle Acque; Spezia, S.; Bettinelli, M. [ENEL, Unified Modelling Language, Piacenza (Italy)

    1999-09-01

    An analytical procedure for the determination of total mercury in wastewaters and natural waters is described. Aqueous samples are fast digested with nitric acid by using the microwave-oven technique; the analysis of mercury is then performed by cold vapor atomic absorption spectrometry (CV-AAS) using two possible instrumental apparatus (batch system or flow injection). Sodium borohydride is used as the reducing agent for mercury in solution (Method A). The use of amalgamation traps on gold for the preconcentration of mercury lowers the detection limit of the analyte (Method B). [Italian] Viene descritta una procedura analitica per la determinazione del mercurio totale in acque di scarico e naturali. Il campione acquoso viene sottoposto a mineralizzazione con acido nitrico in forno a microonde e analizzato mediante spettroscopia di assorbimento atomico a vapori freddi (CV-AAS) in due possibili configurazioni strumentali (sistema batch oppure flow injection), utilizzando sodio boro idruro come agente riducente del mercurio (metodo A). L'impiego della trappola di oro per la preconcentrazione del mercurio mediante amalgama consente di determinare l'analita a livelli di pochi ng/L (metodo B).

  3. Optimized Analytical Method to Determine Gallic and Picric Acids in Pyrotechnic Samples by Using HPLC/UV (Reverse Phase); Optimizacion del Metodo Analitico mediante HPLC/UV Operando en Fase Inversa para la Determinacion de Acido Galico y Acido Picrico en Muestras de Origen Pirotecnico

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    Garcia Alonso, S.; Perez Pastor, R. M.

    2013-10-01

    A study on the optimization and development of a chromatographic method for the determination of gallic and picric acids in pyrotechnic samples is presented. In order to achieve this, both analytical conditions by HPLC with diode detection and extraction step of a selected sample were studied. (Author)

  4. Development of an analytic method for arsenic's determination in lime and tortilla; Desarrollo de un metodo analitico para determinacion de arsenico en cal y tortilla

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    Huato Soberanis, Julio; Ogura, Tetsuya [Universidad Autonoma de Guadalajara, Guadalajara, Jalisco (Mexico)

    1995-02-01

    A spectrophotometric method to determine As in tortilla and lime has been optimized, modifying the AsH{sub 3} generator. The reaction between arsin (AsH{sub 3}){sub 4} and diethyldithiocarbamate of Ag (AgDDC); was followed spectrophotometrically. The conditions under which the As remains in the ash during the calcination of the tortillas were studied. It was found that when they were heated in a quartz tube with a careful control of the air flow and oxygen, as well as the heating temperature, the arsenic loss in minimized. [Spanish] Se ha optimizado el metodo para determinar As en la tortilla y cal mediante espectrometria en el visible del color producido en la reaccion entre Arsina (AsH{sub 3}){sub 4} y dietilditiocarbamato de plata (AgDDC); modificando el generador de AsH{sub 3}. Se han buscado las condiciones en las que el arsenico permanece en las cenizas de la calcinacion de las tortillas; encontrandose que las tortillas deben calentarse en un tubo de cuarzo con control del flujo de aire y oxigeno asi como de la temperatura de calentamiento.

  5. A method for the determination of ascorbic acid using the iron(II)-pyridine-dimethylglyoxime complex

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    Arya, S. P.; Mahajan, M. [Haryana, Kurukshetra Univ. (India). Dept. of Chemistry

    1998-05-01

    A simple and rapid spectrophotometric method for the determination of ascorbic acid is proposed. Ascorbic acid reduces iron (III) to iron (II) which forms a red colored complex with dimethylglyoxime in the presence of pyridine. The absorbance of the resulting solution is measured at 514 nm and a linear relationship between absorbance and concentration of ascorbic acid is observed up to 14 {mu}g ml{sup -1}. Studies on the interference of substances usually associated with ascorbic acid have been carried out and the applicability of the method has been tested by analysing pharmaceutical preparations of vitamin C. [Italiano] Si propone un rapido e semplice metodo spettrofotometrico per la determinazione dell`acido ascorbico. L`acido ascorbico riduce il ferro(III) a ferro(II) che forma con la dimetilgliossima, in presenza di piridina, un complesso colorato in rosso. L`assorbanza della soluzione risultante e` misurata a 514 nm e si ottiene una relazione lineare tra assorbanza e concentrazione dell`acido ascorbico fino a 14 {mu}g ml{sup -1}. Si sono condotti studi sugli interferenti usualmente associati all`acido ascorbico ed e` stata valutata l`applicabilita` del metodo all`analisi di preparati farmaceutici di vitamina C.

  6. Evaluation of methods for wax determination in crude oil; Avaliacao de metodos de determinacao de parafinas em petroleo

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    Dias, Julio Cesar M.; Silva, Maria do Socorro A.J. da; Vasconcellos, Rosa C.U. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Tamanqueira, Juliana B. [Fundacao Gorceix, Ouro Preto, MG (Brazil)

    2008-07-01

    Determining the wax content of crude oil is of great importance for petroleum industry, especially for production, storage and transportation of crude oils. Many different methodologies of wax determining are available in the technical literature. However, the selection of the most suitable method must be in accordance with the aim of the analysis and observing the specificities of each technique. The purpose of this work was to determine the performance of different techniques of wax determining applied to characterization of precipitation properties of waxy compounds in crude oils. Twelve samples of crude oils proceeding from the main Brazilian oil producing sedimentary basins were selected for this study. These samples were analyzed by three important analytical techniques of wax determining: precipitation by cooled solvent; liquid chromatography with precipitation by cooled solvent; and liquid chromatography followed by gas chromatography. Differential scanning calorimetry data related to the wax crystallization in these oils were used as parameters of validation. The results obtained in this study indicate that the liquid chromatography followed by gas chromatography method has the best performance for wax determining in crude oils. (author)

  7. Determination of polycyclic aromatic hydrocarbons (PAHs). gas chromatographic method; Determinazione degli idrocarburi policiclici aromatici (IPA). Metodo gascaromatografico

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    Menichini, E.; Viviano, G. [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Igiene Ambientale

    1997-12-01

    The method enables the determination of 4- to 6- ring PAHs and particularly of carcinogenic PAHs regulated in Italy. This revision is based on the results of a national collaborative study. Sample extract, obtained by a method described in a previous report (Rapporto ISTISAN: 90/33) is cleaned up by thin layer chromatography and analysed by gas chromatography; identification is confirmed by mass spectrometry. An intralaboratory quality control program is described.

  8. Methods of Uranium Determination in solutions of Tributyl Phosphate and Kerosene; Metodos de determinacion de uranio en soluciones de fosfato de tributilo y queroseno

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    Petrement Eguiluz, J.; Palomares Delgado, F.

    1962-07-01

    A new analytical method for the determination of uranium in organic solutions of tributyl phosphate and kerosene is proposed. In this method the uranium is reectracted from the aqueous phase by reduction with cadmium in acid solution. The uranium can be determined in this solution by the usual methods. In case of very diluted solutions, a direct spectrophtometrical determination of uranium in the organic phase with dibenzoylmethane is proposed. (Author) 21 refs.

  9. An alternative method study for determining the content oils and greases derived from spectrophotometric; Estudo de um metodo alternativo para determinacao de oleos e graxas derivado do metodo espectrofotometrico

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    Moura, Leila Rose Benevides; Bezerra, Magna Angelica dos Santos [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Programa de Recursos Humanos da ANP, PRH-14; Melo, Josette Lourdes de Sousa; Melo, Henio Normando de Sousa [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Gomes, Andrea Karla Martins [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Engenharia Quimica

    2004-07-01

    The determination of the Text of Oils and Greases (TOG) it can be done by several methods - gravimetrical or spectrophotometric. That work seeks to study a method alternative spectrophotometric, being compared this with the method used by Curbelo (2002). The modifications were: the reason solvent/sample, and the procedure in which the solvent the sample was mixed. For the method of Curbelo (2002) 100 mL of the sample was mixed to 10 chloroform mL and separated in separation funnel. In the proposed method, adapted denominated Chloroform, the reason was of 20 sample mL for 20 chloroform mL, being this mixture, after manual agitation, taken directly for centrifuge. The medium results were of 81,36 mg/L and 150,44 mg/L for the methods of the Chloroform and Adapted Chloroform, respectively. In spite of the medium values they present differences of almost 50%, it can be verified that the methods demonstrated certain uniformity when evaluated separately, being obtained a minimum deviation of 5,88%. With base in those preliminary results, it can be verified that the developed alternative method gets to remove more oil, mainly for more concentrated samples - exception done to the results of the pattern - and that the two methods present viability of substitution of the gravimetrical methods. (author)

  10. Potentiometric determination of peroxodisulfuric acid during electrolysis sulfuric acid

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    Fedor Malchik

    2013-09-01

    Full Text Available Was proposed two potentiometric methods for determining peroxodisulfuric acid during electrolysis of sulfuric acid (potentiometric titration method and direct potentiometry, based on its interaction with a known excess of a solution Fe2+.

  11. Determination of Sialic Acids by Acidic Ninhydrin Reaction

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    Yao,Kenzabroh

    1987-12-01

    Full Text Available A new acidic ninhydrin method for determining free sialic acids is described. The method is based on the reaction of sialic acids with Gaitonde's acid ninhydrin reagent 2 which yields a stable color with an absorption maximum at 470 nm. The standard curve is linear in the range of 5 to 500 nmol of N-acetylneuraminic acid per 0.9 ml of reaction mixture. The reaction was specific only for sialic acids among the various sugars and sugar derivatives examined. Some interference of this method by cysteine, cystine and tryptophan was noted, although their absorption maxima differed from that of sialic acids. The interference by these amino acids was eliminated with the use of a small column of cation-exchange resin. The acidic ninhydrin method provides a simple and rapid method for the determination of free sialic acids in biological materials.

  12. Spectrophotometric method for the determination of thorium in UO{sub 2} pellets; Metodo espectrofotometrico para la determinacion de torio en pastillas de UO{sub 2}

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    Acosta L, E. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: eal@nuclear.inin.mx

    1995-04-15

    This report presents a procedure with the description of the spectrophotometric method for the determination of the thorium element in uranium products including powders and pellets of uranium dioxide. Quantities can be determined starting from 1 ppm. (Author)

  13. Determination of crystallinity of ceramic materials from the Ruland Method; Determinacao da cristalinidade de materiais ceramicos atraves do metodo de Ruland

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    Kniess, C.T. [Universidade Nove de Julho (UNINOVE), SP (Brazil); Prates, P.B.; Gomes Junior, J.C.; Lima, J.C. de; Riella, H.G.; Kuhnen, N.C., E-mail: kniesscl@gmail.com, E-mail: patybp@gmail.com [Universidade Federal de Santa Catarina (UFSC), SC (Brazil)

    2011-07-01

    Some methods found in literature approach the different characteristics between crystalline and amorphous phases by X ray diffraction technique. These methods use the relation between the intensities of the crystalline peaks and background amorphous or the absolute intensity of one of these to determine the relative amount of crystalline and amorphous material. However, a crystalline substance presents shows coherent diffuse scattering and a loss in the intensity of the peaks of diffraction in function of thermal vibrations of atoms and imperfections in the crystalline structure. A correct method for the determination of the crystallinity must take in account these effects. This work has as objective to determine the crystallinity of ceramic materials obtained with the addition of mineral coal bottom ashes, using the X ray diffraction technique and the Ruland Method, that considers the diminution of the intensity of the crystalline peak because of the disorder affects. The Ruland Method shows adequate for the determination of the crystallinity of the ceramic materials. (author)

  14. Determination of the response time of pressure transducers using the direct method; Determinacao do tempo de resposta de transdutores de pressao utilizando o metodo de medida direta

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    Perillo, S.R.P.

    1994-12-31

    The available methods to determine the response time of nuclear safety related pressure transducers are discussed, with emphasis to the direct method. In order to perform the experiments, a Hydraulic Ramp Generator was built. The equipment produces ramp pressure transients simultaneously to a reference transducer and to the transducer under test. The time lag between the output of the two transducers, when they reach a predetermined setpoint, is measured as the time delay of the transducer under test. Some results using the direct method to determine the time delay of pressure transducers (1 E Class Conventional) are presented. (author). 18 refs, 35 figs, 12 tabs.

  15. Method to determine the activity concentration and total activity of radioactive waste; Metodo para determinar la concentracion de actividad y actividad total de desechos radiactivos

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    Angeles C, A

    2001-02-15

    A characteristic system of radioactive waste is described to determine the concentration of radionuclides activity and the total activity of bundles of radioactive waste. The system this integrated by three subsystems: - Elevator of drums. - Electromechanics. - Gamma spectroscopy. In the system it is analyzed waste of issuing gamma specifically, and this designed for materials of relative low density and it analyzes materials of cylindrical recipients.

  16. Analytical Comparison of Miniaturized Methods for Selected PAH Determination in Clean Waters; Comparacion Analitica de 4 Metodos Miniaturizados de Determinacion de PAHs mediante HPLC en Aguas

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    Garcia, S.; Perez, R. M.; Fernandez, O.

    2012-04-11

    A study on the comparison and evaluation of 4 miniaturized extraction methods for the determination of selected PAHs in clear waters is presented. Four types of liquid-liquid extraction were used for chromatographic analysis by HPLC/ FD. The main objective was the optimization and development of simple, rapid and low cost methods, minimizing the use of extracting solvent volume. The work also includes a study on the scope of the methods developed at low and high levels of concentration. (Author) 13 refs.

  17. Conservative method for determination of material thickness used in shielding of veterinary facilities; Metodo conservativo para determinacao de espessura de materiais utilizados para blindagem de instalacoes veterinarias

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    Lava, Deise D.; Borges, Diogo da S.; Affonso, Renato R.W.; Moreira, Maria de L.; Guimaraes, Antonio C.F., E-mail: deise_dy@hotmail.com, E-mail: diogosb@outlook.com, E-mail: raoniwa@yahoo.com.br, E-mail: malu@ien.gov.br, E-mail: tony@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    For determination of an effective method for shielding of veterinary rooms, was provided shielding methods generally used in rooms which works with X-ray production and radiotherapy. Every calculation procedure is based in traditional variables used to transmission calculation. The thickness of the materials used for primary and secondary shieldings are obtained to respect the limits set by the Brazilian National Nuclear Energy Commission (CNEN). This work presents the development of a computer code in order to serve as a practical tool for determining rapid and effective materials and their thicknesses to shield veterinary facilities. The code determines transmission values of the shieldings and compares them with data from transmission 'maps' provided by NCRP-148 report. These 'maps' were added to the algorithm through interpolation techniques of curves of materials used for shielding. Each interpolation generates about 1,000,000 points that are used to generate a new curve. The new curve is subjected to regression techniques, which makes possible to obtain nine degree polynomial, and exponential equations. These equations whose variables consist of transmission of values, enable trace all the points of this curve with high precision. The data obtained from the algorithm were satisfactory with official data presented by the National Council of Radiation Protection and Measurements (NCRP) and can contribute as a practical tool for verification of shielding of veterinary facilities that require using Radiotherapy techniques and X-ray production.

  18. Trace elements determination in human bone tissue by neutron activation analysis; Determinacao de elementos de traco em tecido osseo humano pelo metodo de ativacao com neutrons

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    Takata, Marcelo K.; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Div. de Radioquimica; Sumita, Nairo M.; Saldiva, Paulo H.N.; Pasqualucci, Carlos A. [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina. Lab. Experimental de Poluicao Atmosferica

    2002-07-01

    Determination of trace elements in human bones is of the great interest for evaluating nutritional state and for prevention, control and study of several diseases caused by mineral or trace element imbalance. In this study, neutron activation analysis (NAA) was applied for trace elements in human rib bone tissue. Elements Ba, Br, Ca, Cl, Fe, K, Mg, Mn, Na, P, Rb, Sr and Zn were determined in total bone tissue and in its subcompartments (cortical and trabecular tissue) separately. Irradiations were performed at IEA-R1 nuclear research reactor of IPEN-CNEN/SP. Short irradiations of 4 minutes were carried out under thermal neutron flux of 4.5x10{sup 11} n cm{sup -2} s{sup -1} and long irradiations of 16 hours under neutron flux of 10{sup 12} n cm{sup -2} s{sup -1}. Results obtained showed a variability between elemental concentrations found for bones from different individuals. A comparative study made between the data obtained for cortical and trabecular bones indicated that these two tissues present different elemental concentrations. Concentrations of Ca, Mg, Na and P obtained for cortical tissue were the same magnitude of those published data. (author)

  19. Determination of Sn in 99{sup m}Tc Radiopharmaceutical Kits by Polarographic Methods; Determinacion de Estano en Radiofarmacos de 99{sup m}Tc mediante Metodos Polarograficos

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    Castro, M.; Cruz, J.; Sanchez, M.

    2009-07-01

    Kits of 99{sup m}Tc radiopharmaceuticals are used in nuclear medicine for diagnosis of different diseases. Sn (II) is one of the essential components in their formulations, which is used for reduction 99{sup m}Tc-pertechnetate in cold kits for on-site preparation 99{sup m}Tc-pertechnetate radiopharmaceuticals. Usually, these cold kits contain different additives (complexing agents, antioxidants, buffers, etc.) and the amount of Sn (II) varies from kit to kit. The determination of Sn in these products is essential in assessing their quality. We report here the development of a new polarographic method for the determination of Sn (II) and total Sn in representative radiopharmaceuticals kits (for the content of Sn and chemical composition) produced at the Center of Isotopes of Cuba (CENTIS). These methods were validated by analysis of variance and recovery techniques. From the results of the validation, the characteristic functions of uncertainties and fits are considered for the established methods, which give the necessary evidences to demonstrate the usefulness of these methods according to the current trends in Analytical Chemistry. This work provides practical results of great importance for CENTIS. After the speciation of Sn in the MAG3 radiopharmaceuticals kit is inferred that the production process is affected by uncontrolled factors that influence in the product stability, which demonstrates the necessity for analytical tools for the characterization of products and processes. (Author) 57 refs.

  20. Trace element determination study in human hair by neutron activation analysis; Estudo da determinacao de elementos traco em cabelos humanos pelo metodo de analise por ativacao com neutrons

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    Frazao, Selma Violato

    2008-07-01

    Human hair analysis studies have been subject of continuous interest due to the fact that they can be used as an important tool to evaluate trace element levels in the human body. These determinations have been carried out to use hair for environmental and occupational monitoring, to identify intoxication or poisoning by toxic metals, to assess nutritional status, to diagnose and to prevent diseases and in forensic sciences. Although hair analysis presents several advantages over other human tissue or fluid analyses, such as organ tissue, blood, urine and saliva, there are some controversies regarding the use of hair analysis data. These controversies arise from the fact that it is difficult to establish reliable reference values for trace elements in hair. The purpose of this study was to evaluate the factors that affect element concentrations in hair samples from a population considered healthy and residing in the Sao Paulo metropolitan area. The collected human head hair was cut in small pieces, washed, dried and analyzed by neutron activation analysis (NAA). Aliquots of hair samples and synthetic elemental standards were irradiated at the IEA-R1 nuclear research reactor for 16 h under a thermal neutron flux of about 5x10{sup 12} n cm{sup -2} s{sup -1} for As, Br, Ca, Co, Cr, Cs, Cu, Fe, K, La, Na, Sb, Sc, Se and Zn determinations. The induced gamma activities of the standards and samples were measured using a gamma ray spectrometer coupled to an hiperpure Ge detector. For quality control of the results, IAEA- 85 Human Hair and INCT-TL-1 Tea Leaves certified reference materials (CRMs) were analyzed. Results obtained in these CRMs presented for most of elements, good agreement with the values of the certificates (relative errors less than 10%) and good precision (variation coefficients less than 13.6%). Results of replicate hair sample analysis showed good reproducibility indicating homogeneity of the prepared sample. Results obtained in the analyses of dyed and

  1. Determination of bacterial endotoxin (pyrogen) in radiopharmaceuticals by the gel clot method. Validation; Determinacao de endotoxina bacteriana (pirogenio) em radiofarmacos pelo metodo de formacao de gel. Validacao

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    Fukumori, Neuza Taeko Okasaki

    2008-07-01

    Before the Limulus amebocyte lysate (LAL) test, the only available means of pirogenicity testing for parenteral drugs and medical devices was the United States Pharmacopoeia (USP) rabbit pyrogen test. Especially for radiopharmaceuticals, the LAL assay is the elective way to determine bacterial endotoxin. The aim of this work was to validate the gel clot method for some radiopharmaceuticals without measurable interference. The FDA's LALTest guideline defines interference as a condition that causes a significant difference between the endpoints of a positive water control and positive product control series using a standard endotoxin. Experiments were performed in accordance to the USP bacterial endotoxins test in the {sup 131}I- m-iodobenzylguanidine; the radioisotopes Gallium-67 and Thallium-201; the lyophilized reagents DTPA, Phytate, GHA, HSA and Colloidal Tin. The Maximum Valid Dilution (MVD) was calculated for each product based upon the clinical dose of the material and a twofold serial dilution below the MVD was performed in duplicate to detect interferences. The labeled sensitivity of the used LAL reagent was 0.125 EU mL{sup -1} (Endotoxin Units per milliliter). For validation, a dilution series was performed, a twofold dilution of control standard endotoxin (CSE) from 0.5 to 0.03 EU mL{sup -1}, to confirm the labeled sensitivity of the LAL reagent being tested in sterile and non pyrogenic water, in quadruplicate. The same dilution series was performed with the CSE and the product in the 1:100 dilution factor, in three consecutive batches of each radiopharmaceutical. The products {sup 131}I-m-iodobenzylguanidine, Gallium-67, Thallium-201, DTPA, HSA and Colloidal Tin were found compatible with the LAL test at a 1:100 dilution factor. Phytate and GHA showed some interference in the gel clot test. Other techniques to determine endotoxins as the chromogenic (color development) and the turbidimetric test (turbidity development), were also assessed to get

  2. Determination of the fast neutrons spectra by the Elastic scattering method (n, p); Determinacion del espectro de neutrones rapidos por el metodo de la dispersion elastica (n, p)

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    Elizalde D, J

    1973-07-01

    This work consists in determining the fast neutron spectra emitted by a Pu-Be isotopic source. The implemented technique is based in the spectrometry (n, p). This consists in making to fall on a fast neutrons beams (polyenergetic) over a thin film of hydrogenated material, detecting the spectra of emitted protons at a fix angle. The polyethylene film and the used solid state detector are inside of a vacuum chamber. The detector is placed at 30 degree with respect to direction of the incident neutrons beam. The protons spectra is stored in a multichannel. the energy is obtained with the prior calibration of the system. The data processing involves the transformation of the protons spectra observed at the falling on neutrons spectra over the film. The energy of the neutrons is related with that of the protons, according to the collision kinematical equations. The cross section of elastic collision of the neutrons with the hydrogen atoms is obtained from literature. Applying these relations to the observed spectra it is obtained the falling on neutron spectra over the film. (Author)

  3. An Optimised Method to Determine PAHs in a Contaminated Soil; Metodo Optimizado para la Determinacion de PAHs en un Suelo Contaminado

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    Garcia Alonso, S.; Perez Pastor, R. M.; Sevillano castano, M. L.; Escolano Segovia, O.; Garcia Frutos, F. J.

    2007-07-20

    An analytical study is presented based on an optimised method to determine selected polycyclic aromatic hydrocarbons (PAHs) by High Performance Liquid Chromatography (HPLC) with fluorescence detection. The work was focused to obtain reliable measurements of PAH in a gas work contaminated soil and was performed in the frame of the project 'Assessment of natural remediation technologies for PAHs in contaminated soils' (Spanish Plan Nacional l+D+i, CTM 2004-05832-CO2-01): First assays were focused to evaluate an initial proposed procedure by sonication extraction in the contaminated soil. Afterwards to extend the efficiency and reduce solvent and time consuming of extraction procedures, the more relevant parameters that affect the extraction step were investigated. A comparison between sonication and microwave procedures was done, and the influence of sample grinding was studied. In general, both extraction techniques led on comparable results, although sonication procedure needs to be more carefully optimised. Finally, as a final application of the optimised method, the effect of particle size on relative distribution of selected PAHs in the contaminated soil was investigated. Relative abundance of more volatile PAHs showed a decreasing according to lower grain size, while relative abundance of less volatile compounds indicated an increasing of concentration levels for lower grain size. (Author) 10 refs.

  4. Determination of titratable acidity in white wine

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    Rajković Miloš B.

    2007-01-01

    Full Text Available The amount of titration acid in must is in the largest number of cases with in the range 5.0-8.0 g/dm3. Wines, as a rule, contain less acids than must, and according to Regulations, titratable acidity is in the range of 4.0-8.0 g/dm3 expressed in tartaric acid, because a part of tartaric acid is deposited in the form of salts (tartar or argol during alcohol fermentation. For wines that contain less than 4 g/dm3 of titratable acids there arises a suspicion about their origin, that is, that during the preparation some illegal acts were done. Because of that, the aim of this paper is to determine titratable acidity in white wine, using standard methods of determination, which are compared with the results received by potentiometric titration using ion-selective electrode. According to the received results it can be seen that wine titration with indicator gives sufficient reliable values of wine titration acidity. However, as potentiometric titration at pH value 7.00 is more reliable and objective method, the values of titratable acids content in wine, expressed through tartaric acid, are given according to this result. The analysis of differential potentiometric curves shows that these curves can give us an answer to the question of the presence of a larger amount of other nonorganic substances, which have already existed in wine. However, none of the used methods gives absolutely reliable answer what substances are present in analysed samples.

  5. Spectrofluorimetric determination of terbium with terephthalic acid

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A spectrofluorimetric method has been developed for the determination of terbium(III) based on the formation of a complex with terephthalic acid [benzene-1, 4-dicarboxylic acid (TPA)] in slightly acidic aqueous solution in the presence of gelatin. Terbium ion can form a stable complex with TPA with the stoichiometry of 1:2. The best excitation and maximum emission wavelengths are observed at 260 nm and 545 nm, respectively. The fluorescence intensity of terbium complex gets the strongest within 20 min and remains stable up to 10 h, and it is proportional to terbium(III) concentration in the range of 4.0(10(5-1.6(10(7 mol@L(1 under the optimum conditions. The fluorescence system has good selectivity, sensitivity and stability. The relative standard deviation is still within (4% in the presence of 1200-fold amounts of the other lanthanide ions when the concentration of terbium(III) is 1.0(10(6 mol@L(1 and common co-existing ions hardly interfere the determination. It has been applied to the direct fluorimetric determination of trace terbium (III) in rare earth ores and oxides.

  6. Seed prepare for oil content determination by NMR method in six cotton varieties; Preparo de sementes para determinacao do teor de oleo pelo metodo de RMN em seis variedades de algodoeiro

    Energy Technology Data Exchange (ETDEWEB)

    Gondim-Tomaz, Rose Marry Araujo; Erismann, Norma de Magalhaes; Sabino, Nelson Paulieri; Kondo, Julio Isao; Cia, Edivaldo; Azzini, Anisio [Instituto Agronomico de Campinas, SP (Brazil). Centro de Algodao e Fibrosas Diversas]. E-mail: gondim@cec.iac.br; Soave, Daise [Instituto Agronomico de Campinas, SP (Brazil). Centro de Genetica, Biologia Molecular e Fitoquimica

    1998-07-01

    Three comparative methods (chemical seed-delinting with sulphuric acid solution, flaming and seed with linter) to prepare cotton seeds for oil determination by the Nuclear Magnetic Resonance (NMR) technique were considered. The chemical treatment with sulphuric acid was the best as long the linter interference was eliminated. The seed oil contents were determined by the NMR method in six cotton varieties from the national variety test. The IAPAR (Instituto Agronomico do Parana) 71 PR3 and IAC (Instituto Agronomico de Campinas) 20 varieties presented the highest oil content followed by the CNPA 7H, CS 50, IAC 22 and CNPA Precoce 2. (author)

  7. Determination of acetylsalicylic acid and salicylic acid in foods, using HPLC with fluorescence detection.

    OpenAIRE

    Venema, D.P.; Hollman, P.C.H.; Janssen, P.L.T.M.K.; Katan, M B

    1996-01-01

    We developed a specific and sensitive HPLC method with fluorescence detection for the determination of free acetylsalicylic acid, free salicylic acid, and free salicylic acid plus salicylic acid after alkaline hydrolysis (free-plus-bound) in foods. Acetylsalicylic acid was detected after postcolumn hydrolysis to salicylic acid. With the method for free acetylsalicylic acid and salicylic acid, recovery was 95-98␏or acetylsalicylic acid added to foods and 92-102␏or salicylic acid. Recovery of a...

  8. Determination of free fatty acids in beer.

    Science.gov (United States)

    Bravi, Elisabetta; Marconi, Ombretta; Sileoni, Valeria; Perretti, Giuseppe

    2017-01-15

    Free fatty acids (FFA) content of beer affects the ability to form a stable head of foam and plays an important role in beer staling. Moreover, the presence of saturated FAs is related sometimes to gushing problems in beer. The aim of this research was to validate an analytical method for the determination of FFAs in beer. The extraction of FFAs in beer was achieved via Liquid-Liquid Cartridge Extraction (LLCE), the FFAs extract was purified by Solid Phase Extraction (SPE), methylated by boron trifluoride in methanol, and injected into GC-FID system. The performance criteria demonstrate that this method is suitable for the analysis of medium and long chain FFAs in beer. The proposed method was tested on four experimental beers.

  9. Spectrophotometric determination of tranexamic acid using vanillin

    Institute of Scientific and Technical Information of China (English)

    EM.A.Rind; M.G.H.Laghari; A.H.Memon; U.R.Mughal; F. Almani; N.Me-mon; M.Y.Khuhawar; M.L.Maheshwari

    2009-01-01

    A new spectrophotometric method has been examined for the determination of the tranexamic acid (TA)by derivatization with vanillin(VAN).The molar absorptivity of TA was calculated 25 160 L·mol-1·cm-1at λ max 354 nm and obeyed the Beer's law within 0.5-2.5 μg·mL-1.The color reaction was highly stable and didnot show any change in absorbance up to 24 h.The method was applied for the analysis of TA from capsules,injections and tooth pastes.The amounts of TA found in capsules,injections and tooth pastes of various pharmaceutical companies were observed with 249.0-250.9 mg/capsule,249.3-250.7 mg/injection and 0.048%-0.049%in tooth pastes with relative standard deviation(RSD)0.2%-5.0%(n=3).

  10. Determination of isocyanic acid in air.

    Science.gov (United States)

    Karlsson, D; Dalene, M; Skarping, G; Marand, A

    2001-08-01

    A method is presented for the determination of isocyanic acid (ICA), HNCO, in air samples as a di-n-butylamine (DBA) derivative. The method is based on sampling in midget impinger flasks containing 10 ml of 0.01 mol l-1 DBA in toluene. Quantification was made using liquid chromatography (LC) and electrospray mass spectrometry (MS) monitoring positive ions. The instrumental detection limit for the LC-MS was 10 fmol of ICA-DBA. ICA was generated by thermal decomposition of urea. A standard solution containing the DBA derivatives of ICA was prepared by collecting the emitted ICA in an impinger flask containing DBA. ICA in the reference solution was characterised by LC and time-of-flight (TOF) MS and quantified by LC chemiluminescent nitrogen detection (LC-CLND). The instrumental detection limit for the LC-CLND was 1 ng of nitrogen. ICA was emitted during thermal degradation of PFU resins and polyurethane (PUR) lacquers, from car metal sheets. ICA was the most dominant isocyanate and in PUR coating up to 8% of the total weight was emitted as ICA and for PFU resins up to 14% was emitted as ICA. When air samples were collected in an iron foundry during casting in sand moulds with furan resins, concentrations of ICA in the range 50-700 micrograms m-3 were found in the working atmosphere.

  11. Determination of acetylsalicylic acid and salicylic acid in foods, using HPLC with fluorescence detection.

    NARCIS (Netherlands)

    Venema, D.P.; Hollman, P.C.H.; Janssen, P.L.T.M.K.; Katan, M.B.

    1996-01-01

    We developed a specific and sensitive HPLC method with fluorescence detection for the determination of free acetylsalicylic acid, free salicylic acid, and free salicylic acid plus salicylic acid after alkaline hydrolysis (free-plus-bound) in foods. Acetylsalicylic acid was detected after postcolumn

  12. Analytical method for determination of benzene-arsenic acids

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, G.L.; Bayse, G.S.

    1988-01-01

    A sensitive analytical method has been modified for use in determination of several benzenearsonic acids, including arsanilic acid (p-aminobenzenearsonic acid), Roxarsone (3-nitro-4-hydroxybenzenearsonic acid), and p-ureidobenzene arsonic acid. Controlled acid hydrolysis of these compounds produces a quantitative yield of arsenate, which is measured colorimetrically as the molybdenum blue complex at 865 nm. The method obeys Beer's Law over the micromolar concentration range. These benzenearsonic acids are routinely used as feed additives in poultry and swine. This method should be useful in assessing tissue levels of the arsenicals in appropriate extracts.

  13. Analytical methods for 2,4-D (Dichlorophenoxyacetic acid) determination; Metodos analiticos para la determinacion del 2,4-D (Acido diclorofenoxiacetico)

    Energy Technology Data Exchange (ETDEWEB)

    Martinez G, M.S.M

    1999-06-01

    The 2,4-D herbicide is one of the main pesticides for controlling the bad grass in crops such as the water undergrowth. In Mexico the allowed bound of this pesticide is 0.05 mg/l in water of 2,4-D so it is required to have methods trusts and exacts, which can used in order to detected low concentration of it. In this work we show some for the conventional techniques and for establishing the 2,4-D concentrations. The UV-Vis spectrometer and liquids chromatography due that they are the most common used nowadays. Beside, we introduce a now developed technique, which is based on the neutronic activation analysis. Though use of the UV-Vis spectrometer technique it was possible target the concentrations interval between 1 and 200 mg/l. In the liquids chromatography interval was between 0.1 and 0.9, and by the neutronic activation analysis the interval was between 0.01 and 200 mg/l. (Author)

  14. [Determination of glutamic acid in biological material by capillary electrophoresis].

    Science.gov (United States)

    Narezhnaya, E; Krukier, I; Avrutskaya, V; Degtyareva, A; Igumnova, E A

    2015-01-01

    The conditions for the identification and determination of Glutamic acid by capillary zone electrophoresis without their preliminary derivatization have been optimized. The effect of concentration of buffer electrolyte and pH on determination of Glutamic acid has been investigated. It is shown that the 5 Mm borate buffer concentration and a pH 9.15 are optimal. Quantitative determination of glutamic acid has been carried out using a linear dependence between the concentration of the analyte and the area of the peak. The accuracy and reproducibility of the determination are confirmed by the method "introduced - found". Glutamic acid has been determined in the placenta homogenate. The duration of analysis doesn't exceed 30 minutes. The results showed a decrease in the level of glutamic acid in cases of pregnancy complicated by placental insufficiency compared with the physiological, and this fact allows to consider the level of glutamic acid as a possible marker of complicated pregnancy.

  15. Determination of peracetic acid and hydrogen peroxide in the mixture

    OpenAIRE

    Bodiroga Milanka; Ognjanović Jasminka

    2002-01-01

    Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2) in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A). Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction...

  16. A modification of a method for phytic acid determination

    OpenAIRE

    DRAGUTIN VELICKOVIC; BILJANA VUCELIC-RADOVIC; SRDJAN BLAGOJEVIC; MIROLJUB BARAC; SLADJANA STANOJEVIC; MAJA LJUBICIC

    1999-01-01

    Several different methods for the determination of phytic acid which do not require sophisticated equipment are currently in use. These methods have been developed to measure the phytic acid content of a variety of materials, such as plant tissues, food stuffs and soils. The aim of the work was to modify the supernatant difference, macro-method developed by Erdman and Thompson1 for the determination of the phytic acid content in soybeans and soybean protein products. A micro-method was develo...

  17. Use of radioanalytical methods for determination of uranium, neptunium, plutonium, americium and curium isotopes in radioactive wastes; Utilizacao de metodos radioanaliticos para a determinacao de isotopos de uranio, plutonio, americio e curio em rejeitos radioativos

    Energy Technology Data Exchange (ETDEWEB)

    Geraldo, Bianca

    2012-07-01

    Activated charcoal is a common type of radioactive waste that contains high concentrations of fission and activation products. The management of this waste includes its characterization aiming the determination and quantification of the specific radionuclides including those known as Difficult-to-Measure Radionuclides (RDM). The analysis of the RDM's generally involves complex radiochemical analysis for purification and separation of the radionuclides, which are expensive and time-consuming. The objective of this work was to define a methodology for sequential analysis of the isotopes of uranium, neptunium, plutonium, americium and curium present in a type of radioactive waste, evaluating chemical yield, analysis of time spent, amount of secondary waste generated and cost. Three methodologies were compared and validated that employ ion exchange (TI + EC), extraction chromatography (EC) and extraction with polymers (ECP). The waste chosen was the activated charcoal from the purification system of primary circuit water cooling the reactor IEA-R1. The charcoal samples were dissolved by acid digestion followed by purification and separation of isotopes with ion exchange resins, extraction and chromatographic extraction polymers. Isotopes were analyzed on an alpha spectrometer, equipped with surface barrier detectors. The chemical yields were satisfactory for the methods TI + EC and EC. ECP method was comparable with those methods only for uranium. Statistical analysis as well the analysis of time spent, amount of secondary waste generated and cost revealed that EC method is the most effective for identifying and quantifying U, Np, Pu, Am and Cm present in charcoal. (author)

  18. Determination of the presence of hyaluronic acid in preparations containing amino acids: the molecular weight characterization.

    Science.gov (United States)

    Bellomaria, A; Nepravishta, R; Mazzanti, U; Marchetti, M; Piccioli, P; Paci, M

    2014-10-15

    Several pharmaceutical preparations contain hyaluronic acid in the presence of a large variety of low molecular weight charged molecules like amino acids. In these mixtures, it is particularly difficult to determine the concentration and the molecular weight of the hyaluronic acid fragments. In fact zwitterionic compounds in high concentration behave by masking the hyaluronic acid due to the electrostatic interactions between amino acids and hyaluronic acid. In such conditions the common colorimetric test of the hyaluronic acid determination appears ineffective and in the (1)H NMR spectra the peaks of the polymer disappear completely. By a simple separation procedure the presence of hyaluronic acid was revealed by the DMAB test and (1)H NMR while its average molecular weight in the final product was determined by DOSY NMR spectroscopy alone. The latter determination is very important due to the healthy effects of some sizes of this polymer's fragments.

  19. Determination of peracetic acid and hydrogen peroxide in the mixture

    Directory of Open Access Journals (Sweden)

    Bodiroga Milanka

    2002-01-01

    Full Text Available Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2 in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A. Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction was used for the quantitative iodometric determination of total peroxide in procedure B. H2O2 reacted with potassium permanganate in acid medium, but peracetic acid did not react under the same conditions. That made possible the selective permanganometric determination of H2O2 in the presence of peracetic acid. The procedure B was performed in two titration vessels (KV=3.4% for peracetic acid, 0.6% for H2O2. The procedure A for iodometric determination of peracetic acid in one titration vessel after permanganometric titration of H2O2 was recommended (KV=2,5% for peracetic acid, 0,45% for H2O2.

  20. MERITEV PROSTANOIDOV V KRVNI PLAZMI Z METODO GC/MS

    OpenAIRE

    Lisac, Nejc

    2014-01-01

    V seminarju obravnavamo biosintezo, kemijsko zgradbo in pomen eikozanoidov v človeškem organizmu. Preučimo metodo priprave vzorca krvne plazme, postopke meritev ter kvalitativne in kvantitativne analize prostanoidov z uporabo plinskega kromatografa in masnega spektrometra. Na podlagi analize masnih spektrov z uporabo internih standardov določimo koncentracijo prisotnih prostanoidov v vzorcu.

  1. A method for the determination of D(-)-lactic acid

    NARCIS (Netherlands)

    Hamer, C.J.A. van den; Elias, R.W.

    1958-01-01

    A method for the determination of D(—)-lactic acid is described. An acetone powder from Escherichia coli B in the presence of methylene blue oxidizes D(—)-lactic specifically. Oxygen consumption in a Warburg apparatus was used as a measure of the D(—)-lactic acid.

  2. Evaluation of human dental loss caused by carbamide peroxide bleacher compared with phosphoric acid conditioning - radioactive method; Avaliacao da perda dental humana com o uso do clareador peroxido de carbamida comparado ao condicionamento com acido fosforico - metodo radiometrico

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Eduardo Makoto; Yousseff, Michel Nicolau [Sao Paulo Univ., SP (Brazil). Faculdade de Odontologia. Dept. de Dentistica; Saiki, Mitiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Lab. de Analise por Ativacao Neutronica

    2002-07-01

    The radiometric method was applied to the evaluation of dental loss caused by carbamide peroxide when it is applied on the surface layers of enamel and dentin tissues. Also the dental loss caused by the etching with 37% phosphoric acid procedure used in aesthetic restoration was assessed for comparison with those results obtained. The tooth samples irradiated with a P standard in a thermal neutron flux of the nuclear reactor were placed in contact with 10% carbamide peroxide or with 37% phosphoric acid solution. The radioactivity of {sup 32} P transferred from the radioactive teeth to the bleaching gel or to etching acid was measured using a Geiger Muller detector to calculate the mass of P removed in this treatment and losses were calculated after obtaining their P concentrations. Results obtained indicated that enamel and dentin exposed to carbamide peroxide bleaching agent lose phosphorus. The extent of enamel loss was smaller than that obtained for dentin. In the case of acid etching, there was no difference between the results obtained for enamel and dentin loss. Also the dentin loss obtained after a treatment of 30 applications of 10% carbamide peroxide was the same magnitude of that one application of 37% phosphoric acid. (author)

  3. Two new methods to determine the adhesion by means of internal friction in materials covered with films; Dos nuevos metodos para determinar la adhesion mediante friccion interna en materiales recubiertos con peliculas

    Energy Technology Data Exchange (ETDEWEB)

    Colorado, H. A.; Ghilarducci, A. A.; Salva, H. R.

    2006-07-01

    Two new models are proposed to determine the adhesion energy be means of the internal friction technique (IF) in thin films layered materials. for the first method is necessary to determine enthalpy by means of the IF technique, for which the adhesion work has been determined with experimental data. In the second method are necessary to perform IF tests at constant temperature. (Author)

  4. Determinants of folic acid knowledge and use among antenatal women.

    LENUS (Irish Health Repository)

    McDonnell, R

    1999-06-01

    Although recommendations on folic acid use were issued by health authorities in a number of countries in the early 1990s, uptake of peri-conceptional folic acid is still disappointingly low. Regardless of food fortification policies, folic acid promotion will probably be required in most countries to optimize folate levels among women of child-bearing age. The aim of this study was to examine folic acid knowledge and use, and their determinants among antenatal women in the east of Ireland in 1997.

  5. Separation and determination of some carboxylic acids by capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Sladkov, V.; Fourest, B

    2006-07-01

    Separation and determination of some organic acids, mono-carboxylic (formic and acetic), dicarboxylic (oxalic and tartaric), tricarboxylic (citric) acids and aromatic acids (phtalic, benzoic, mellitic and trimellitic), by capillary electrophoresis are reviewed. The method development parameters, such as separation and injection mode, are discussed. Special attention is paid to the comparison of different detection types (spectroscopic and electrochemical). The optimisation of the carrier electrolyte composition (choice of carrier electrolyte, effect of pH, ionic strength, electro-osmotic flow modifier) is treated. Different additives (alkali-earth and transition metal ions, cyclodextrins and alcohol), which are often used for improving organic acid separation, are also considered. (authors)

  6. Determination of chlorogenic acid by flow injection irreversible biamperometry

    Institute of Scientific and Technical Information of China (English)

    Li Jun Li; Qi Feng Chen; Lai Bo Yu; Zhao Heng Zhong; Jun Feng; Hao Cheng; Hong Xing Kong; Jian Ling Wu

    2007-01-01

    A flow injection irreversible biamperometric method for the determination of chlorogenic acid is described. The proposed method is based on the electrochemical oxidation of chlorogenic acid at pretreated platinum electrode and the reduction of permanganate at another electrode to form an irreversible biamperometric detection system. Under the external potential difference(△E) of 0 V, in the 0.05 mol/L sulfuric acid, chlorogenic acid can be determined over the range 0.8-120 mg/L with a sample measurement frequency of 80 samples/h. The detection limit is 0.18 mg/L. The proposed method exhibits the satisfactory reproducibility with a relative standard derivation (R.S.D.) of 2.21% for 19 successive determinations of 40 mg/L.

  7. [Spectrophotometric determination of aromatic amino compounds with J-acid].

    Science.gov (United States)

    Yin, Xiao-hang; Shi, Wen-jian; Shen, Xin; Ma, Jun-tao; Li, Liang

    2015-01-01

    The problems such as chromogenic reaction selectivity, reaction rate, sensitivity and water-solubility of azo compounds were considered. The molecular structures of coupling components were theoretically designed and screened in the present research The reaction conditions and methods of chromogenic reaction were investigated. J-Acid (2-amino-5-naphthol-7-sulfonic acid) as a coupling reagent to determine aromatic amino compounds was established. In the presence of potassium bromide, at room temperature, nitrite reacted with aromatic amino compounds in the medium of thin hydrochloric acid. Then diazonium salt reacted with J-Acid in the aqueous solution of sodium carbonate, forming coloured azo dye, which had a maximum adsorption at 480 nm. The molar adsorption coeffcients of aniline, 4-aminobenzene sulfonic acid and 1-naphthylamine were 3. 95 X 10(4), 3. 24 X 10(4) and 3. 91 X 10(4) L . mol-1 . cm-1 , respectively. Experimental results showed that common coexisting ions on the surface water did not affect the results of determination. J-Acid of spectrophotometry was used to determine the samples of Shanghai Fu Xing Dao canal. Meanwhile, recovery experiments by standard addition method were done. Experiment results showed that the recoveries of aniline were in the range of 98. 5%-102. 1%, and RSD was 2. 08%. J-Acid is a common organic reagent. It is soluble in water and low volatile, and its toxicity is much lower than N-ethylenediamine. spectrophotometric determination of aromatic amino compounds by J-Acid has the advantage of high sensitivity, good selectivity, simple rapid operation and accurate results, and thus it can be used for the determination of trace aromatic amino compounds in the environmental water.

  8. Analytical method of Kr-85 determination, using cryogenic concentration and separation and liquid scintillation counting; Desarrollo del metodo de concentracion y se paracion criogenica cromatografica y medida radiactiva por centelleo liquido de Kr-85

    Energy Technology Data Exchange (ETDEWEB)

    Heras, M. C.; Perez, M. M.; Grau, A.

    1983-07-01

    The method used in the Laboratory of the JEN for the determination of Kr-85 levels in gaseous effluents of nuclear power and in the atmosphere is described. Samples of air, collected in metallic cylinders, are introduced into a gas-solid chromatographic separation system which resolves Kr from the other air components. The separated Kr ia dissolved in a toluene based scintillation cocktail, and the Kr-85 content is determined by liquid scintillation counting. (Author)

  9. The two means method for the attenuation coefficient determination of archaeological ceramics from the North of Parana; Metodo dos dois meios para a determinacao do coeficiente de atenuacao de ceramicas arqueologicas do norte do Parana

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Richard Maximiliano Cunha e

    1997-12-31

    This work reports an alternative methodology for the linear attenuation coefficient determination ({mu} {rho}) of irregular form samples, in such a way that is not necessary to consider the sample thickness. With this methodology, indigenous archaeological ceramics fragments from the region of Londrina, north of Parana, were studied. These ceramics fragments belong to the Kaingaing and Tupiguarani traditions. The equation for the {mu} {rho} determination employing the two mean method was obtained and it was used for {mu} {rho} determination by the gamma ray beam attenuation if immersed ceramics, by turns, in two different means with known linear attenuation coefficient. By the other side, {mu} theoretical value was determined with the XCOM computer code. This code uses as input the ceramics chemistry composition and provides an energy versus mass attenuation coefficient table. In order to validate the two mean method validation, five ceramics samples of thickness 1.15 cm and 1.87 cm were prepared with homogeneous clay. Using these ceramics, {mu} {rho} was determined using the attenuation method, and the two mean method. The result obtained for {mu} {rho} and its respective deviation were compared for these samples, for the two methods. With the obtained results, it was concluded that the two means method is good for the linear attenuation coefficient determination of materials of irregular shape, what is suitable, specially, for archaeometric studies. (author) 25 refs., 29 figs., 28 tabs.

  10. Determination of primary nitroparaffins by the nitrous acid reaction

    Energy Technology Data Exchange (ETDEWEB)

    Altshuller, A.P.; Cohen, I.R.

    1960-06-01

    The determination of nitroparaffins and particularly of primary nitroparaffins was reviewed recently. A spectrophotometric method for determining microgram quantities of primary nitroparaffins by coupling with diazotized sulfanilic acid was described. In the course of investigating the gas-phase products of olefins and nitrogen oxides, the reactions of some representative members of various classes of nitroparaffins with nitrous acid also were measured. This type of reaction goes back to the classical red, white and blue reaction of Meyer and Locher. The blue reaction of nitrous acid with secondary nitroparaffins was investigated as a colorimetric procedure. In the present work the nitrous acid reaction with primary nitroparaffins is of immediate interest, but the reactions of secondary nitroparaffins, dinitroparaffins, and a variety of nitroalcohols also are measured. 8 references, 1 table.

  11. Fluorometric determination of uric acid in bovine milk

    DEFF Research Database (Denmark)

    Larsen, Torben; Moyes, Kasey

    2010-01-01

    The primary objective of this study is to validate a new fast method for determination of uric acid in milk. The method is based on an enzymatic-fluorometric technique that requires minimal pre-treatment of milk samples. The present determination of uric acid is based on the enzymatic oxidation...... at -18°C for 24 h. Addition of either allopurinol (a xanthine oxidase inhibitor) or dimethylsulfoxide (a solvent for allopurinol) did not affect milk uric acid concentrations (P=0·96) and may indicate that heat treatment before storage and analysis was sufficient to degrade xanthine oxidase activity...... of uric acid to 5-hydroxyisourate via uricase where the liberated hydrogen peroxide reacts with 10-acetyl-3,7-dihydroxyphenoxazine via peroxidase and the fluorescent product, resorufin, is measured fluorometrically. Fresh composite milk samples (n=1,072) were collected from both Jersey (n=38) and Danish...

  12. Paint samples preparation methods for metals and methaloids determination by atomic spectrometry techniques; Estudo comparativo de metodos de preparo de amostras de tinta para a determinacao de metais e metaloides por tecnicas de espectrometria atomica

    Energy Technology Data Exchange (ETDEWEB)

    Bentlin, Fabrina R.S.; Pozebon, Dirce; Depoi, Fernanda dos Santos [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica], e-mail: dircepoz@iq.ufrgs.br

    2009-07-01

    This work deals with paint decomposition methods for major, minor and trace elements determination. Three methods were investigated: (1) decomposition in closed quartz vessel and heating in microwave oven; (2)decomposition in open vessel using HNO{sub 3} and ashing, following the ASTM D 3335-85a method; and (3) decomposition in open vessel using HNO{sub 3} + HF and ashing. Paints of different types and colours were analyzed, in which several elements were determined using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP OES). It was observed that method (1) is appropriate for trace, minor and major elements determination, while method (3) is appropriate for Ti. (author)

  13. Determination and Correlation for Solubility of Aromatic Acids in Solvents

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Solubility of benzoic acid, terephthalic acid and 2,6-naphthalene dicarboxylic acid in water, acetic acid, N,N-dimethyfformamide, N,N-dimethylacetamide, dimethyl sulphoxide and N-methyl-2-ketopyrrolidine were measured by dynamic method. The solubilities were calculated by UNIFAC group contribution method, in which new groups, BCCOOH and NCCOOH, were introduced to express the activity coefficients of aromatic acids and new interaction parameters of the new groups were expressed as the function of temperature, which were determined from the experimental data. The new interaction parameters provided good calculated result. The experimental data were also correlated with Wilson and λ-h models, and results were compared with present UNIFAC model.

  14. Fluorimetric determination of pipemidinic acid using the europium chelate.

    Science.gov (United States)

    Egorova, A; Beltyukova, S; Teslyuk, O

    1999-11-01

    The sensitized luminescence of europium ion in the complexes with pipemidinic acid is investigated. It was shown that in the result of intramolecular energy transfer from ligand to lanthanide ion the luminescence intensity of the latter increases by 10(10) times. The luminescence properties of the complex were studied and the high sensitive luminescence method for the determination of pipemidinic acid has been developed.

  15. The LTS{sub N} method used for the determination of parameters in heterogeneous shielding for neutrons and photons; O uso do metodo LTS{sub N} na obtencao de parametros de blindagens multiplas para neutrons e fotons

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Volnei [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Dept. de Engenharia Nuclear; Francio, Laci Maria; Brigoni, Justina Ines Fronza [Universidade de Caxias do Sul, RS (Brazil). Dept. de Ciencias Exatas e da Natureza

    2002-07-01

    In this work the LTS{sub N} methodology is used for determination of the radiation flux distribution into the homogeneous and heterogeneous shielding, using the multigroup model in energy, for photons and neutrons. Numerical results for emergent flux, absorbed dose rates and buildup factor are reported. (author)

  16. Two media method for linear attenuation coefficient determination of irregular soil samples; Metodo dos dois meios para a determinacao do coeficiente de atenuacao linear de amostras irregulares de solos

    Energy Technology Data Exchange (ETDEWEB)

    Vici, Carlos Henrique Georges

    2004-07-01

    In several situations of nuclear applications, the knowledge of gamma-ray linear attenuation coefficient for irregular samples is necessary, such as in soil physics and geology. This work presents the validation of a methodology for the determination of the linear attenuation coefficient ({mu}) of irregular shape samples, in such a way that it is not necessary to know the thickness of the considered sample. With this methodology irregular soil samples (undeformed field samples) from Londrina region, north of Parana were studied. It was employed the two media method for the {mu} determination. It consists of the {mu} determination through the measurement of a gamma-ray beam attenuation by the sample sequentially immersed in two different media, with known and appropriately chosen attenuation coefficients. For comparison, the theoretical value of {mu} was calculated by the product of the mass attenuation coefficient, obtained by the WinXcom code, and the measured value of the density sample. This software employs the chemical composition of the samples and supplies a table of the mass attenuation coefficients versus the photon energy. To verify the validity of the two media method, compared with the simple gamma ray transmission method, regular pome stone samples were used. With these results for the attenuation coefficients and their respective deviations, it was possible to compare the two methods. In this way we concluded that the two media method is a good tool for the determination of the linear attenuation coefficient of irregular materials, particularly in the study of soils samples. (author)

  17. Development of an equipment based in microcomputer for the determination of synchronous machine parameters through the frequency response method; Desenvolvimento de um equipamento baseado em microcomputador para determinacao de parametros de maquinas sincronas atraves do metodo de resposta em frequencia

    Energy Technology Data Exchange (ETDEWEB)

    Costa Bortoni, Edson da; Jardini, Jose Antonio [Sao Paulo Univ., SP (Brazil). Escola Politecnica

    1995-12-31

    This work presents the development of a equipment to be used for the determination of synchronous machines parameters though the frequency response method. The methodology is presented. A case study based on literature data is presented 9 figs., 2 tabs., 7 refs.

  18. A Simple Analytical Method Using HPLC with Fluorescence Detection to Determine Selected Polycyclic Aromatic Compounds in Filter Samples; Metodo Analitico Sencillo para la Determinacion de Compuestos Aromaticos Policiclicos en Muestras de Filtros mediante HPLC con Detector de Fluorescencia

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, S.; Perez, R. M.

    2014-06-01

    A study on the comparison and evaluation of a miniaturized extraction method for the determination of selected PACs in sample filters is presented. The main objective was the optimization and development of simple, rapid and low cost methods, minimizing the use of extracting solvent volume. The work also includes a study on the intermediate precision. (Author)

  19. Microscale adaptation of the potentiometric method with ion-selective electrode for the quantification of fluoride; Adaptacion a microescala del metodo potenciometrico con electrodo ion selectivo para la cuantificacion de fluoruro

    Energy Technology Data Exchange (ETDEWEB)

    Guevara Ruiz, Paulina; Ortiz Perez, Maria Deogracias [Laboratorio de Bioquimica, Facultad de de Medicina, Universidad Autonoma de San Luis Potosi, San Luis Potosi, San Luis Potosi, (Mexico)]. E-mail: mdortiz@uaslp.mx

    2009-05-15

    Similarly to other countries, ground water from Mexico is naturally polluted by fluoride. The main effects of fluoride at typical ground water concentrations are dental fluorosis, neurological deficits and reproductive disorders. In order to verify that the fluoride concentration is within the allowed guideline in Mexico (NOM 127 and 201), it is important to monitor fluoride levels in water and commercial beverages. The aim of this work is to develop a modification of the standard potentiometric method for fluoride determination in water, in order to reduce costs and amount of potentially toxic waste substances. Both methods were validated, the standard potentiometric method with the ion selective electrode and the microscale modification proposed in this paper. The methods were compared using statistic tests and graphics, followed by the comparison of 125 samples of commercial bottled water sold in the city of San Luis Potosi. Optimal results were obtained for the validation of both methods, and the microscale modification showed statistically identical results to those obtained with the standard method in all samples of bottled water. The microscale modification is a good alternative for fluoride assessment in water and beverages, and it represents a 95 % reduction of costs and chemical waste. [Spanish] En varios paises, incluido Mexico se presenta una contaminacion natural con fluoruro en agua subterranea; los principales efectos en la salud observados en poblacion expuesta a concentraciones mayores al valor permisible (que en Mexico es de 1.5 mg/L) son la fluorosis dental y esqueletica, asi como dano reproductivo y neurologico. En varios estados de la republica Mexicana, este problema es aun desconocido, de ahi la necesidad de evaluar las concentraciones de fluoruro en agua de consumo en varias comunidades. Asi, el objetivo de este trabajo es desarrollar un metodo a microescala para la determinacion de fluoruro en agua, que al reducir la cantidad de reactivo y

  20. Determination of rare earth and uranium in reference biological materials certified by the method of neutron activation analysis; Determinacao de terras raras e de uranio em materiais biologicos de referencia certificados pelo metodo de analise por ativacao com neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Lais H.P.; Saiki, Mitiko, E-mail: laispaciulli@gmail.com, E-mail: mitiko@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    The objective of this study was to evaluate the precision and accuracy of the determinations of Sc, La, Ce, Nd, Sm, Eu, Tb, Yb, Lu and U in certified reference materials (CRMs). To solve the problem of interference from fission products of U in the determination of lanthanides were obtained correction factors for this interference for {sup 140}La, {sup 141}Ce, {sup 143}Ce, {sup 153}Sm and {sup 147}Nd. The experimental procedure of Neutron Activation Analysis consisted of irradiating aliquots of each of the CRMs with synthetic standards of elements under thermal neutron flux of the IEA-R1 nuclear reactor, followed by gamma-ray spectrometry using a high-resolution hyperpurity GE detector. The analyzes of CRMs indicate good accuracy and precision of results, demonstrating the feasibility of applying of established procedure in NAA of elements studied in organic vegetable matrices.

  1. Contribution to the spectrographic determination of impurities in uranium by the carrier distillation method; Nuevas aportaciones a la determinacion espectrografica de impurezas en materiales de uranio por el metodo de distilacion fraccionada con portador

    Energy Technology Data Exchange (ETDEWEB)

    Capdevila, C.

    1967-07-01

    The carrier distillation method for the determination of impurities in uranium has been modified in order to get a greater sensitivity. Electrodes 9.5 mm. diam. with a crater 7 mm. diam. and 10 mm. deep have been used, being the weigh of charge 300 mg.. The elements considered were: Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, P, Pb, Si, Sn, Ti and V, over the range 0.01 to 30 ppm. (Author) 13 refs.

  2. Semi-empirical determination of the diffusion coefficient of the Fricke Xylenol Gel dosimeter through finite difference methods; Determinacao semi-empirica do coeficiente de difusao do dosimetro Fricke Xilenol Gel atraves do metodo de diferencas finitas

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, E.O.; Oliveira, L.N., E-mail: lucas@ifg.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Goias (IFG), Goiania, GO (Brazil)

    2014-11-01

    Partial Differential Equations (PDE) can model natural phenomena, such as related to physics, chemistry and engineering. For these classes of equations, analytical solutions are difficult to be obtained, so a computational approach is indicted. In this context, the Finite Difference Method (FDM) can provide useful tools for the field of Medical Physics. In this study, is described the implementation of a computational mesh, in order to be used in determining the Diffusion Coefficient (DC) of the Fricke Xylenol Gel dosimeter (FXG). The initial and boundary conditions both referred by experimental factors are modelled in FDM, thus making a semi-empirical study in determining the DC. Together, the method of Reflection and Superposition (SRM) and the analysis of experimental data, served as first validation for the simulation. Such methodologies interface generated concordant results for a range of error of 3% in concentration lines for small times when compared to the analytical solution. The result for the DC was 0.43 mm{sup 2} /h. This value is in concordance with measures parameters range found in polymer gels dosimeters: 0.3-2.0 mm{sup 2} /h. Therefore, the application of computer simulation methodology supported by the FDM may be used in determining the diffusion coefficient in FXG dosimeter. (author)

  3. Drawing up of a procedure for vanadium determination in mussels using the neutron activation analysis method; Estabelecimento de procedimento para determinacao de vanadio em mexilhoes pelo metodo de analise por ativacao com neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Daniele, E-mail: danyseo@uol.com.b [Universidade Presbiteriana Mackenzie, Sao Paulo, SP (Brazil). Centro de Ciencias Biologicas e da Saude; Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Vasconcellos, Marina B.A.; Saiki, Mitiko; Catharino, Marilia G.M.; Moreira, Edson G., E-mail: mbvascon@ipen.b, E-mail: mitiko@ipen.b, E-mail: mgcatharino@uol.com.b, E-mail: emoreira@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Sousa, Eduinetty C.P.M. de; Pereira, Camilo D.S., E-mail: edvinett@usp.b, E-mail: camilo.pereira@usp.b [Universidade de Sao Paulo (IO/USP), SP (Brazil). Inst. Oceanografico. Lab. de Ecotoxicologia Marinha

    2009-07-01

    This work establishes an adequate procedure for obtaining reliable results for determination of vanadium in mussels, leg by leg by the neutron activation analysis (NAA), viewing the posterior application on the bio monitoring the coastal pollution, particularly near the petroleum terminals.For the evaluation of result quality concerning to the quality of those results, the work analysed the reference material certification NIST SRM 1566b Oyster Tissue. The precision of the results were also analysed using repetitions of mussel samples collected at the coastal of northern Sao Paulo state, Brazil. The NAA procedure consisted of 200 mg of sample and a synthetic standard of vanadium during a period of 8 s and under a thermal neutron flux of 6.6 x 10{sup 12} n cm{sup -2} s{sup -1} at the pneumatic station 4 of the IEA-R1 nuclear reactor of IPEN-CNEN/SP. After a 3 min decay, the measurements of the gamma activities of the sample and the standard were done using a Ge hyper pure semi-conductor detector, connected to gamma ray multichannel analyser. The vanadium were determined by the measurement of the gamma activity of the {sup 52}V through the 1434.08 keV peak, and half-life time of 3.75 min. The concentration of V were calculated by the comparative method. The obtained results indicated the viability of the NAA procedure established for the determination of vanadium in mussels

  4. Study of the reaction between {sup 51}CrO{sub 3} and concentrated nitric acid by radio chromatographic methods; Estudo da reacao entre {sup 51}CrO{sub 3} e acido nitrico concentrado por metodos radiocromatograficos

    Energy Technology Data Exchange (ETDEWEB)

    Pezzin, Sergio H. [Univesidade do Estado de Santa Catarina (UDESC), Joinville, SC (Brazil). Centro de Ciencias Tecnologicas; Collins, Carol H.; Collins, Kenneth E. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Quimica

    2000-07-01

    The objective of the present work is to verify the reduction of CrO{sub 3} in concentrated nitric acid, using {sup 51}Cr as a tracer. For the study, {sup 51}CrO{sub 3} (ca. 200,000 cpm/mg) was added to 65% HNO{sub 3} and maintained under agitation at 20 deg C for specified time periods. Aliquots (100 {mu}) were analyzed by open column cation (AG50Wx8, 100-200 mesh, Na{sup +} form) chromatography, either immediately or after dilution to approximately pH 2 and storage for specified time periods. The separations, which were made by stepwise elution using HClO{sub 4} and Ca(ClO{sub 4}){sub 2} solutions as effluents with fraction collection, followed by counting with a NaI(Tl) detector and a single channel analyzer. It was verified that ca. 3.5% of Cr(III) is obtained after 15 min of reaction. The major reaction product is hexaaquo chromium(III), with minor concentrations of mononitrate penta-aquochromium(III), [Cr(H{sub 2}O){sub 5}NO{sub 3}]{sup 2+}, a product which undergoes watering at pH 2 to produce, after 360 h, [Cr(H{sub 2}O){sub 6}]{sup 3+}. (author)

  5. Analysis of a calculation method for the determination of the value of safety or control bars; Analisis de un metodo de calculo para la determinacion del valor de barras de seguridad o control

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar H, F.; Torres A, C.; Filio L, C. [ININ, Gcia. de Reactores, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1982-09-15

    Due to the control or safety bars in a nuclear reactor are constituted by strongly absorbent materials, the Diffusion Theory like tool for the calculation of bar values is not directly applicable, should it use the Transport Theory. However the speed and economy of the Diffusion codes for the reactors calculation, those make attractiveness and by this reason its are used in the determination of characteristic parameters and even in the determination of bar values, not without before to make some theoretical developments that allow to make applicable this theory. The application of the Diffusion Theory in strongly absorbent media is based on the use of some effective cross sections distinct from the real ones obtained when imposing the reason that among the flow and it gradient in the external surface of such media (control element in general, bar type or flagstone) be similar to the one obtained using Transport Theory in all the control region (multiplicative and absorbent media) with those real cross sections. The effective cross sections were obtained of the Leopard-NUMICE cell code which has incorporate the respective calculation theory of effective cross sections. Later these constants its were used in the bidimensional diffusion code Exterminator-II, simulating in it, the distribution of safety or control bars. From the cell code its were also obtained the respective constants of the homogeneous fuel cell. The results as soon as those obtained bar values of the diffusion code, its were compared with some experimental results obtained in the R{phi} Swedish reactor of natural uranium and heavy water. In this work an analysis of the bar value of one of them, trying to determine the applicability of the method is made. (Author)

  6. Alternative method for determination of radiochemical purity of {sup 99m}Tc-MIBI; Metodo alternativo para a determinacao de pureza radioquimica de MIBI-{sup 99m}Tc

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Elisiane G.; Almeida, Erika V.; Benedetti, Stella; Alves, Edson V.; Fukumori, Neuza T.O.; Matsuda, Margareth M.N., E-mail: elisianegmonteiro.farmacia@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Diretoria de Radiofarmacia

    2010-07-01

    {sup 99m}Tc-MIBI ({sup 99m}Tc-2-metoxyisobutylisonitrile) is prescribed for scintigraphy images of myocardial perfusion and assessment of patients with myocardium infarct at risk. The determination of the radiochemical purity (RCP) of {sup 99m}Tc-MIBI in international pharmacopoeias involves the use of a chromatographic method in thin layer with reverse phase (TLC-RP) for determination of % {sup 99m}TcO{sub 4}-, % {sup 99m}TcO2 e % product and also the analysis by high performance liquid chromatography (HPLC). The aim of this work was to determine radiochemical purity (RCP) in {sup 99m}Tc-MIBI by an alternative method to that described in international pharmacopoeias. Paper chromatography (PC) and instant thin layer chromatography (ITLC-SG) with ethyl acetate: methanol (8:2) as mobile phase and thin layer chromatography (TLC-SG) with 0.9% saline were used. The results of % product, %{sup 99m}TcO{sub 4}- and %{sup 99m}TcO{sub 2} obtained by TLC-RP were (97.98 {+-} 0.07)%, (1.49 {+-} 0.07)% and (0.53 {+-} 0.06)%, respectively. In PC, {sup 99m}TcO4- and {sup 99m}TcO2 have Rf = 0.0 and the percentage of impurities was (2.70 {+-} 0.33)%, while the radiochemical purity was (97.31 {+-} 0.33)%. In ITLC-SG, only {sup 99m}TcO2 remains at the origin (Rf = 0,0) with (0.69 {+-} 0.08)%. However, since there was the interruption in the manufacture of ITLC-SG, it was necessary to look for other stationary phases. In this work it was demonstrated that the quality control of {sup 99m}Tc-MIBI can be performed by PC (% Impurities) and TLC-SG (%{sup 99m}TcO4-) as an alternative method for the determination of radiochemical purity. (author)

  7. Analytical Evaluation to Determine Selected PAHs in a Contaminated Soil With Type II Fuel; Metodo Optimizado de Extraccion por Ultrasonidos para la Determinacion de PAHs Seleccionados en un Suelo Contaminado con Fuel de Tipo II

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Alonso, S.; Perez Pastor, R. M.; Sevillano Castano, M. L.; Garcia Frutos, F. J.

    2010-10-21

    A study on the optimization of an ultrasonic extraction method for selected PAHs determination in soil contaminated by type II fuel and by using HPLC with fluorescence detector is presented. The main objective was optimize the analytical procedure, minimizing the volume of solvent and analysis time and avoiding possible loss by evaporation. This work was carried out as part of a project that investigated a remediation process of agricultural land affected by an accidental spillage of fuel (Plan Nacional I + D + i, CTM2007-64 537). The paper is structured as: Optimization of wavelengths in the chromatographic conditions to improve resolution in the analysis of fuel samples. Optimization of the main parameters affecting in the extraction process by sonication. Comparison of results with those obtained by accelerated solvent extraction. (Author) 3 refs.

  8. Analytical Evaluation to Determine Selected PAHs by HPLC in a Type 2 Fuel; Evaluacion Analitica de 4 Metodos de Determinacion de PAHs medianteHPLC en un Fuel de Tipo II

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Alonso, S.; Perez Pastor, R. M.; Sevillano Castano, M. L.; Escolano Segovia, O.; Garcia Frutos, F. J.

    2009-05-21

    An evaluation of analytical parameters to determine selected PAHs in a fuel oil type II by HPLC coupled to fluorescence and diode detectors is presented. The study was focused on four conventional treatments of these kinds of oil samples and the main objective was giving a measure of confidence level of PAH results in the fuel oil. This study was performed in the frame of the project Assessment of natural attenuation of PAHs in agricultural soil contaminated with fuel from an accidental spill (Spanish National Plain I+D+I, CTM2007-64537). This paper is presented as follows: Analysis of reference material 1582 (NIST) by using the four kinds of sample treatments of interest. Application of variance analysis to compare results obtained from type II fuel by using each sample treatment and chromatographic detector. Finally, a statistic calculation was performed to measure uncertainty components in chromatographic analysis. (Author)

  9. Determination of viscosity of fayalite slags for kv model and measurements by means of inclined plane; Estimacion de la viscosidad de escorias fayaliticas utilizando el modelo de calculo kv y el metodo experimental del plano inclinado

    Energy Technology Data Exchange (ETDEWEB)

    Bazan, V.; Goni, C.; Castella, L.; Brandaleze, E.; Verdeja, L. F.; Parra, R.

    2006-07-01

    The viscosity of the lands represents one of the most relevant variables of most of the processes metallurgical and kinetics of the refine operations, since it is one of the decisive factors of the efficiency in the reactions between metal and lag, as much as slag-refractory. In the last decades, the mathematical models of different metallurgical processes have established methods to predict viscosity of mixtures of oxides fused to high temperatures in function of the chemical composition. The model developed by Toguri, based on the data reported by Johasen and Winterhager et al has proposed the Kv model. The used index it is similar to the relationship used in the steel industry like the basicity index. It is presented in this work values determined of viscosity in experimental form by means of the technique of inclined plane. (Author)

  10. Evaluation of analyte additions method for sodium determination in fuel ethanol by flame atomic emission spectrometry; Avaliacao do metodo das adicoes de analito para a determinacao de sodio em alcool combustivel por espectrometria de emissao atomica em chama

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Adriana Paiva de; Okumura, Leonardo Luiz; Gomes Neto, Jose Anchieta [UNESP, Araraquara, SP (Brazil). Inst. de Quimica. Dept. de Quimica Analitica

    2002-07-01

    The analyte additions method was applied for sodium determination in fuel ethanol by atomic emission spectrometry. Graphics involving emission intensity versus analyte concentration in the 0 - 0.300 mg Na L{sup -1} interval concentration range containing 2.1 g K L{sup -1} as an ionisation buffer. Twenty samples of commercial fuel ethanol were collected in different gas stations located in Araraquara city, analyzed and results obtained varied from 0.0072 to 1.55 mg Na L{sup -1}. The limits of detection (L.O.D.) varied from 0.0026 to 0.0239 mg Na L{sup -1}. Recoveries varied in the 95 - 104 % interval. The relative standard deviations (n=12) for three analyte additions in all samples were {<=}4,1 %. (author)

  11. Uncertainty Evaluation and Influence of Gran Size to Determine PAHs in a Contaminated Soil; Influencia del Tamano de Particula de un Suelo Contaminado en las Incertidumbres Asociadas al Metodo de Determinacion de PAHs

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Alonso, S.; Perez Pastor, R. M.; Escolano Segoviano, O.; Garcia Frutos, F. J.

    2007-07-20

    An evaluation of uncertainty associated to PAH determination in a contaminated soil is presented. The work was focused to measure the influence of grain size on concentration deviations and give a measure of result confidence of PAHs in the gasworks contaminated soil. This study was performed in the frame of the project 'Assessment of natural remediation technologies for PAHs in contaminated soils'(Spanish Plan Nacional I+D+i, CTM 2004-05832-CO2-01). This paper is presented as follows: A brief introduction which describes the main uncertainty contributions associated to chromatographic analysis. Afterwards, a statistic calculation was performed to measure each uncertainty component. Finally, a global uncertainty was calculated and the influence of grain size and distribution of compounds according to volatility was evaluated. (Author) 10 refs.

  12. Determination of acidity constants of enolisable compounds by capillary electrophoresis.

    Science.gov (United States)

    Mofaddel, N; Bar, N; Villemin, D; Desbène, P L

    2004-10-01

    Research on the structure-activity relationships of molecules with acidic carbon atoms led us to undertake a feasibility study on the determination of their acidity constants by capillary electrophoresis (CE). The studied molecules had diverse structures and were tetronic acid, acetylacetone, diethylmalonate, Meldrum's acid, 3-methylrhodanine, nitroacetic acid ethyl ester, pyrimidine-2,4,6-trione, 3-oxo-3-phenylpropionic acid ethyl ester, 1-phenylbutan-1,3-dione, 5,5-dimethylcyclohexan-1,3-dione and homophthalic anhydride. The p Ka range explored by CE was therefore very large (from 3 to 12) and p Ka values near 12 were evaluated by mathematical extrapolations. The analyses were carried out in CZE mode using a fused silica capillary grafted (or not) with hexadimethrine. Owing to the electrophoretic behaviour of these compounds according to the pH, their acidity constants could be evaluated and appeared in perfect agreement with the literature data obtained, a few decades ago, by means of potentiometry, spectrometry or conductimetry. The p Ka of homophthalic anhydride and 3-methylrhodanine were evaluated for the first time.

  13. Validation of lignocellulosic biomass carbohydrates determination via acid hydrolysis.

    Science.gov (United States)

    Zhou, Shengfei; Runge, Troy M

    2014-11-04

    This work studied the two-step acid hydrolysis for determining carbohydrates in lignocellulosic biomass. Estimation of sugar loss based on acid hydrolyzed sugar standards or analysis of sugar derivatives was investigated. Four model substrates (starch, holocellulose, filter paper and cotton) and three levels of acid/material ratios (7.8, 10.3 and 15.4, v/w) were studied to demonstrate the range of test artifacts. The method for carbohydrates estimation based on acid hydrolyzed sugar standards having the most satisfactory carbohydrate recovery and relative standard deviation. Raw material and the acid/material ratio both had significant effect on carbohydrate hydrolysis, suggesting the acid to have impacts beyond a catalyst in the hydrolysis. Following optimal procedures, we were able to reach a carbohydrate recovery of 96% with a relative standard deviation less than 3%. The carbohydrates recovery lower than 100% was likely due to the incomplete hydrolysis of substrates, which was supported by scanning electron microscope (SEM) images.

  14. Subsurface microbial ecology. Epi fluorescence direct counts; Ecologia microbica del sottosuolo: metodo di conta diretta in epifluorescenza

    Energy Technology Data Exchange (ETDEWEB)

    Barra Caracciolo, A.; Silvestri, C.; Creo, C.; Izzo, G. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

    1998-07-01

    To the aim of recognize the importance of microorganisms in affecting or even determining the fate of xenobiotics in the subsurface environment evaluating bacteria concentration in a subsurface ecosystem, the report discusses a soil sample treatment method which has been developed for epi fluorescence direct counting with DAPI. [Italian] Lo studio discute un metodo di trattamento del campione per la conta diretta in epifluorescenza con un marcatore selettivo per il DNA, il DAPI, al fine di quantificare la concentrazione batterica del sottosuolo e studiare il ruolo dei microrganismi nella biodegradazione delle molecole esogene, ancora poco indagato.

  15. Simultaneous determination of geniposidic acid, chlorogenic acid and geniposide in eucommia by HPLC

    Institute of Scientific and Technical Information of China (English)

    李宇萍; 陈晓青; 彭密军; 贺前峰; 出山武

    2003-01-01

    A high performance liquid chromatography (HPLC) method was established for simultaneous determina-tion of geniposidic acid, chlorogenic acid and geniposide in eucommia. Detection at 240 nm with a reversed-phasecolumn, CH3OH volume fraction, acidic additive and pH value of mobile phase were studied for their effects on theseparability of the compounds. The most suitable separation was obtained with isocratic gradient elution systemusing CH3OH-H2O-H3 PO4 (12.00: 87.96: 0.04, volume ratio) at a flow-rate of 1.0 mL/min. Under the experi-mental conditions, the capacity factors of three compounds are in 3-13. The sample is separated rightly. Theanalysis time is 30 min and the retention time of genfposidic acid, chlorogenic acid and geniposide are 6. 7 min,10.5 min and 21 min, respectively.

  16. Determination of aqueous acid-dissociation constants of aspartic acid using PCM/DFT method

    Science.gov (United States)

    Sang-Aroon, Wichien; Ruangpornvisuti, Vithaya

    Determination of acid-dissociation constants, pKa, of aspartic acid in aqueous solution, using density functional theory calculations combined with the conductor-like polarizable continuum model (CPCM) and with integral-equation-formalism polarizable continuum model (IEFPCM) based on the UAKS and UAHF radii, was carried out. The computed pKa values derived from the CPCM and IEFPCM with UAKS cavity model of bare structures of the B3LYP/6-31+G(d,p)-optimized tetrahydrated structures of aspartic acid species are mostly close to the experimental pKa values.0

  17. Quantitative determination of glycyrrhizinic acid by square-wave

    Directory of Open Access Journals (Sweden)

    Aneta Dimitrovska

    2003-06-01

    Full Text Available Novel adsorptive stripping square-wave voltammetric method as well as a new high-pressure liquid chromatographic method for direct determination of glycyrrhizinic acid in dosage pharmaceutical preparation, used against virus infections, have been developed. Glycyrrhizinic acid is an electrochemically active compound, which undergoes irreversible reduction on a mercury electrode surface in an aqueous medium. Its redox properties were studied thoroughly by means of square-wave voltammetry, as one of the most advanced electroanalytical technique. The voltammetric response depends mainly on the pH of the medium, composition of the supporting electrolyte, as well as the parameters of the excitement signal. It was also observed that the voltammetric properties strongly depend on the accumulation time and potential, revealing significant adsorption of glycyrrhizinic acid onto the mercury electrode surface. Upon this feature, an adsorptive stripping voltammetric method for quantitative determination of glycyrrhizinic acid was developed. A simple, sensitive and precise reversed phase HPLC method with photodiode array UV detection has also been developed, mainly for comparison and conformation of the results obtained with the voltammetric method.

  18. The need of alkalinity determination in the characterization of rain; Necesidad de la determinacion de la alcalinidad en la caracterizacion de la lluvia

    Energy Technology Data Exchange (ETDEWEB)

    Pal Verma, Mahendra [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1998-01-01

    In this paper is presented the alkalinity determination of the carbonic species in the rain waters by the Gran titration method. The alkalinity values obtained by this method in low electric conductivity waters are fairly reliable. Also, the existing studies on the characterization of acid rains, are discussed. [Espanol] En este trabajo se presenta la medicion de la alcalinidad y la determinacion de las especies carbonicas en las aguas de lluvia por el metodo de la titulacion de Gran. Los valores de alcalinidad obtenidos por este metodo en las aguas de baja conductividad electrica son bastante confiables. Asimismo, se discuten los estudios existentes sobre la caracterizacion de la lluvia acida en la republica mexicana.

  19. New analyser for the determination of urinary vanillylmandelic acid, homovanillic acid and creatinine.

    Science.gov (United States)

    Kawaguchi, S; Hirachi, N; Fukamachi, M

    1991-06-14

    We have developed a novel analyser for the determination of vanillylmandelic acid, homovanillic acid and creatinine in urine by high-performance liquid chromatography using three different types of column, cation-exchange, anion-exchange and reversed-phase and the column-switching technique. In this procedure, 10 microliters of intact urine were directly injected into the cation-exchange column, and the pass-through fraction, containing vanillylmandelic acid and homovanillic acid was transferred to the anion-exchange column by column switching. The fraction partially purified from endogenous urinary impurities on the anion-exchange column was transferred to the reversed-phase column. Vanillylmandelic acid and homovanillic acid, separated by the solvent-switching technique, were detected fluorimetrically (excitation at 280 nm, emission at 320 nm). Then, creatinine eluted from the cation-exchange column is spectrophotometrically detected (254 nm). Therefore the successive simultaneous analysis of the three could be performed in a 15-min cycle; the within-assay coefficients of variation for normal and patients' urines were less than 1.9%, less than 3.3% and less than 3.0% for vanillylmandelic acid, homovanillic acid and creatinine, respectively; the recoveries averaged 100, 103 and 100%, respectively, for supplemented urines.

  20. Contributions te the study of methods and factors affecting the spectrophotometric determination of boron traces with carmin uranium compounds; Contribucion al estudio del metodo y factores que afectan a la determinacion espectrofotometrica de trazas de boro con Carmin en compuestos de uranio

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez Cellini, R.; Gasco Sanchez, L.

    1956-07-01

    The study of some factors affecting the spectrophotometric determination of boron traces with carmin is made; the influence of carmin from different origin, the stability of complex carmin-boric acid in relation with the sulphuric acid concentration, the interference produced by ion nitrate, and the ion uraline and light influence are discussed. (Author) 36 refs.

  1. Simultaneous liquid-chromatographic determination of urinary vanillylmandelic acid, homovanillic acid, and 5-hydroxyindoleacetic acid.

    Science.gov (United States)

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

    1988-12-01

    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.

  2. Vitamin B2 content determination in liver paste by using acid and acid-enzyme hydrolysis

    Directory of Open Access Journals (Sweden)

    Basić Zorica

    2007-01-01

    Full Text Available Background/Aim. Vitamin B2 is available in foodstuff in the form of coenzyme and in free form. For its content determination a few procedures should be performed (deliberation from a complex, extraction of free and deliberated form and detection, identification and quantification. There is a particular problem in determination of vitamin B2 in the meat products. For a determination of total vitamin B2 content in liver paste two preparation procedures are compared: acid and acid-enzymatic hydrolysis. The aim of this study thus, was to compare the effectiveness of these two different procedures for vitamin B2 content determination in liver paste. Methods. High pressure liquid chromatography (HPLC method with fluorescence detector, as specific and adequately sensitive for the foodstuff of a complex composition with a natural vitamin content, was used for determination of vitamin B2 in liver paste. Acid hydrolysis was performed with the application 0.1 M hydrochloric acid in a pressure cooker, and enzymatic hydrolysis was performed with the 10% takadiastase on 45 ºC within four hours. Ten samples of liver paste from the supply of the Serbian Army were examined. Separation was performed on the analytical column Nucleosil 50−5 C18 with mobile phase 450 ml CH3OH + 20 ml 5 mM CH3COONH4, and detection on the fluorescent detector with the variable wave length. Both methods were validated: examining a detection limit, quantification limit, specificity (because of a possible B2 vitamin interference with reagents, linearity of a peak area and standard concentration of B2 vitamin ratio in the range from 0.05 μg/ml to 2 μg/ml, precision for the 0.05 μg/ml concentration and recovery. Results. All the previously examined parameters validated both methods as specific, precise and reproductive, with a high recovery (98.5% for acid and 98.2% for acid - enzymatic hydrolysis, as well as linearity in a range that significantly superseded the expected content in

  3. Simultaneous determination of chlorogenic acid, caffeic acid, alantolactone and isoalantolactone in Inula helenium by HPLC.

    Science.gov (United States)

    Wang, Jin; Zhao, Yong-ming; Zhang, Man-li; Shi, Qing-wen

    2015-04-01

    A rapid and sensitive high-performance liquid chromatographic (HPLC) method was developed for the simultaneous separation and determination of chlorogenic acid, caffeic acid, alantolactone and isoalantolactone in Inula helenium. The HPLC separation was performed on an Elite Hypersil C18 column (200 × 4.6 mm i.d., 5 µm particle size) with a gradient elution of solvent A (acetonitrile) and solvent B (0.1% phosphoric acid in water) at a flow rate of 1.0 mL/min. Detection was monitored at 225 nm. The recovery of chlorogenic acid ranged from 95.6 to 107.7%, the recovery of caffeic acid ranged from 95.4 to 104.2%, the recovery of alantolactone ranged from 95.8 to 100.8% and the recovery of isoalantolactone ranged from 96.5 to 102.3%. The retention times for chlorogenic acid, caffeic acid, alantolactone and isoalantolactone were 5.2, 7.1, 25.6 and 26.6 min with the limits of detection of 0.069, 0.021, 0.039 and 0.051 µg/mL, respectively. Relative standard deviation for the intra-day and inter-day was ≤2.5%. The validated method is reliable for the routine control of these four compounds in I. helenium.

  4. Determination of femtomol quantities of gibberellic acid by radioimmunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Weiler, E.W.; Wieczorek, U.

    1981-01-01

    A highly sensitive and specific radioimmunoassay which allows the detection of as little as 5 fmol (2 pg) of gibberellic acid (GA/sub 3/) in crude plant extracts is described. Antisera of high affinity and titer were obtained by immunizing rabbits with a conjugate of carboxyl-coupled GA/sub 3/ and bovine serum albumin. (/sup 125/I) Gibberellic acid-(N-(p-hydroxybenzyl) putrescine) amide of high specific activity, used as the immunotracer, is readily displaced by gibberellic acid methyl ester but not by free gibberellic acid. Thus, methylation of extracts prior to analysis is required. The assay is very specific; besides GA/sub 3/, only the closely related GA/sub 7/ is highly immunoreactive. Various gibberellins, related compounds, as well as other classes of plant hormones do not interfere with the assay. Levels of immunoreactive gibberellins (GA/sub 3/, GA/sub 7/) in actively growing tissues, among them cell suspension cultures of 33 different species, were determined.

  5. Simultaneous determination of salicylic acid and salicylamide in biological fluids

    Science.gov (United States)

    Murillo Pulgarín, J. A.; Alañón Molina, A.; Sánchez-Ferrer Robles, I.

    2011-09-01

    A new methodology for the simultaneous determination of salicylic acid and salicylamide in biological fluids is proposed. The strong overlapping of the fluorescence spectra of both analytes makes impossible the conventional fluorimetric determination. For that reason, the use of fluorescence decay curves to resolve mixtures of analytes is proposed; this is a novel technique that provides the benefits in selectivity and sensitivity of the fluorescence decay curves. In order to assess the goodness of the proposed method, a prediction set of synthetic samples were analyzed obtaining recuperation percentages between 98.2 and 104.6%. Finally, a study of the detection limits was done using a new criterion resulting in values for the detection limits of 8.2 and 11.6 μg L -1 for salicylic acid and salicylamide respectively. The validity of the method was tested in human serum and human urine spiked with aliquots of the analytes. Recoveries obtained were 96.2 and 94.5% for salicylic acid and salicylamide respectively.

  6. HPLC determination of valproic acid in human serum.

    Science.gov (United States)

    Kishore, P; Rajani Kumar, V; Satyanarayana, V; Krishna, D R

    2003-06-01

    A HPLC method for the determination of valproic acid (VA) in human serum using diazepam as internal standard (I.S.) is described. The eluates were separated with a C18 250 x 4.6 mm internal diameter reversed phase column maintained at a temperature of 50 degrees C. A mobile phase consisting of acetonitrile and 0.05 M phosphate buffer (pH 3.0) 45:55 v/v was used at a flow rate of 1.2 ml/min. Wavelength was switched from 360 nm to 210 nm during valproic acid retention. The method was linear over a concentration range of 20 to 160 microg/ml for valproic acid. Recovery was greater than 94% over a concentration range of 20 to 120 microg/ml and the limit of quantitation was 1 microg/ml. The intra day and inter day relative standard deviation (R.S.D.) measured at 20, 60, 80 and 120 microg/ml ranged from 1.46 to 5.34% and 0.83 to 5.03% respectively. The method is simple, rapid, accurate and sensitive and it was used for Therapeutic Drug Monitoring (TDM) in Indian epileptic patient population. The results obtained with this method correlated well with clinical practice.

  7. ION-EXCLUSION CHROMATOGRAPHIC DETERMINATION OF CARBOXYLIC ACIDS USED TO SUPPORT THE MICROBIALLY MEDIATED REDUCTIVE DECHLORINATION OF TETRACHLOROETHENE

    Science.gov (United States)

    An analytical method was developed for the determination of lactic acid, formic acid, acetic acid, propionic acid, and butyric acid in environmental microcosm samples using ion-exclusion chromatography. The chromatographic behavior of various eluents was studied to determine the ...

  8. Polarographic determination of metyrosine through treatment with nitrous acid.

    Science.gov (United States)

    Aly, F A; Belal, F; el-Brashy, A

    1993-10-15

    A simple and sensitive polarographic method is described for the determination of metyrosine through treatment with nitrous acid. The different experimental parameters affecting the derivatization process, as well as the polarographic analysis were studied. The derivatization product was found to be reducible at the dropping mercury electrode over the whole pH range in Britton Robinson buffers. At pH 5, a well-defined diffusion-controlled cathodic wave was produced. The limiting current versus the concentration plot was linear over the range 8-80 mumol/l in the direct current mode with a detection limit of 0.2 mumol/l. The method was then applied to the determination of metyrosine capsules, and the results obtained were in good agreement with those given by the USP method.

  9. Potentiometric determination of the total acidity of humic acids by constant-current coulometry.

    Science.gov (United States)

    Palladino, Giuseppe; Ferri, Diego; Manfredi, Carla; Vasca, Ermanno

    2007-01-16

    A straightforward method for both the quantitative and the equilibrium analysis of humic acids in solution, based on the combination of potentiometry with coulometry, is presented. The method is based on potentiometric titrations of alkaline solutions containing, besides the humic acid sample, also NaClO(4) 1M; by means of constant current coulometry the analytical acidity in the solutions is increased with a high precision, until the formation of a solid phase occurs. Hence, the total acid content of the macromolecules may be determined from the e.m.f. data by using modified Gran plots or least-squares sum minimization programs as well. It is proposed to use the pK(w) value in the ionic medium as a check of the correctness of each experiment; this datum may be readily obtained as a side-result in each titration. Modelling acid-base equilibria of the HA samples analysed was also performed, on the basis of the buffer capacity variations occurring during each titration. The experimental data fit, having the least standard deviation, was obtained assuming a mixture of three monoprotic acids (HX, HY, HZ) having about the same analytical concentration, whose acid dissociation constants in NaClO(4) 1M at 25 degrees C were pK(HX)=3.9+/-0.2, pK(HY)=7.5+/-0.3, pK(HZ)=9.5+/-0.2, respectively. With the proposed method the handling of alkaline HA solutions, the titration with very dilute NaOH or HCl solutions and the need for the availability of very small volumes of titrant to be added by microburettes may be avoided.

  10. Diagnostic value of prostatic acid phosphatase as determined by radioimmunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Wirth, M.P.; Osterhage, H.R.; Ackkermann, R.

    1981-07-01

    Serum concentrations of prostatic acid phosphatase (PAP) were determined with 4 different radioimmunoassays and with the standard enzymatic method (p-nitrophenylphosphate) in 35 patients with prostatic carcinoma. Staging of localized tumors was based on histopathological evaluation after radial prostatectomy and pelvic lymphnode dissection (pTsub(1-3), pN/sub 0/). In tumor lesions Tsub(1-2) N/sub 0/ M/sub 0/ elevated PAP-serum concentrations were found by RIA-determination in only one patient. Increased PAP serum levels were observed in 43-78% of carcinomas stage T/sub 3/ N/sub 0/ M/sub 0/ and in 54-83% in stage Tsub(2-4) Nsub(x) M/sub 1/ tumors, depending on the test kit used for the PAP determination. Concentrations for PAP obtained with the 4 different RIA-kits used, varied significantly and thus are not comparable. No false positive results were observed in sera of 9 patients with benign prostatic hyperplasia. Elevated PAP serum levels were found in a significantly higher frequency when determined by radioimmunoassay than by the enzymatic method. The results clearly indicate, that PAP is of no value for early recognition of carcinoma of the prostate even when measured by radioimmunoassay. However, the RIA-method seems to be of clinical importance in estimating the course of advanced local and metastasizing carcinoma of the prostate.

  11. Volatile organic compounds determination in the atmosphere of Mexico City by the use of optical systems and non conventional methods; Determinacion de compuestos organicos volatiles en la atmosfera de la Ciudad de Mexico mediante el uso de sistemas opticos y metodos convencionales

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Maria Esther; Arriaga, Jose Luis; Garcia, Isidoro [Gerencia de Ciencias de Ambiente, Instituto Mexicano del Petroleo, Mexico, D.F. (Mexico)

    1996-04-01

    Since 1991, volatile organic compounds (VOC) have been determined in Mexico City Metropolitan Area (MCMA) using different analyzing methods. Samples collected in cartridges and canisters area analyzed by GC-MS and HPLC. Continuos monitoring by a long path differential absorption analyzer (DOAS) has also been performed. The Mexican Petroleum Institute (IMP) along with the USEPA and the collaboration of the Mexican environmental authorities have performed, following the EPA TO-14 method, four sampling campaigns of ambient air in canisters among 1992 and 1993. The campaigns were designed to be performed during March, month in which the worst ozone episodes have taken place. Additional sampling was performed in November in order to compare differences between seasons. In March 1993, samples in three different kinds of cartridges were used which selectively adsorb carbonyl compounds, light hydrocarbons (C{sub 2}-C{sub 4}) and heavier hydrocarbons (C{sub 5}-C{sub 1}5). The three techniques employed, canisters, cartridges and the DOAS, reveal very high atmospheric concentrations of the volatile organic compounds, species identified as ozone precursors, these high concentration might appear as responsible for the ozone standards excess. The kinetics of the whole set of atmospheric reactions points then to nitrogen oxides as the limiting species since their relative smaller abundance. This fact engender a NOx limited atmosphere. The three techniques offer different advantages for the determination of species in the atmosphere, the canisters samples provides the total VOC concentration, the speciation of more than 200 compounds and the determination of CO and CH{sub 4}. The sampling in cartridges could be used to detect occasional emissions. On the other hand the DOAS provides the means to follow the evolution of selected species during long periods and the influence of meteorological parameters as the wind speed and direction, on the concentration of each pollutant. The

  12. Determination of residues in honey after treatments with formic and oxalic acid under field conditions

    OpenAIRE

    Bogdanov, Stefan; Charrière, Jean-Daniel; IMDORF, Anton; KILCHENMANN, Verena; Fluri, Peter

    2002-01-01

    International audience; Formic acid and oxalic acid field trials for control of Varroa destructor were carried out in autumn according to the Swiss prescriptions during three successive years in different apiaries in Switzerland. The following parameters were determined in honey that was harvested the year after treatment: formic acid, oxalic acid and free acidity. The following range of values were found in honeys of untreated colonies: formic acid, from 17 to 284 mg/kg, n = 34; oxalic acid,...

  13. Determination of free fatty acids in beer wort.

    Science.gov (United States)

    Bravi, Elisabetta; Benedetti, Paolo; Marconi, Ombretta; Perretti, Giuseppe

    2014-05-15

    The importance of free fatty acids (FFAs) in wort has been known for a long time because of their influence on beer quality and yeast metabolism. Lipids have a beneficial effect on yeast growth during fermentation as well as negative effects on beer quality. Lipids content of beer affects the ability to form a stable head of foam and plays an important role in beer staling. Moreover, the ratio of unsaturated and saturated fatty acids seems to be related to gushing problems. A novel, simple, and reliable procedure for quantitative analysis of FFAs in wort was developed and validated. The determination of FFAs in wort was achieved via liquid-liquid cartridge extraction, purification of FFA fraction by solid phase extraction, boron trifluoride in methanol methylation, and injection into GC-FID system. The proposed method has high accuracy (<0.3%, expressed as the bias), high precision (<1.2%, RSD), and recoveries ranging from 74% to 98%. The method was tested on two different wort samples (9° and 12° Plato).

  14. Liquid chromatographic determination of beta-naphthoxyacetic acid in tomatoes.

    Science.gov (United States)

    Gökmen, V; Acar, J

    1998-03-06

    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.

  15. Determination of Fatty Acid in Asparagus by Gas Chromatography

    Directory of Open Access Journals (Sweden)

    Zehra HAJRULAI-MUSLIU

    2016-05-01

    Full Text Available Asparagus contain a lot of macronutrients and micronutrients including folate, dietary fibre (soluble and insoluble and phenolic compounds. Also asparagus is a good source of unsaturated linoleic and linolenic fatty acids which are precursors for Eicosapentanoic acid (EPA and Docosahexanoic acid (DHA. Unsaturated fatty acids have important biological effects and they have important role in human health. The objective of this study was to analyze fatty acid composition of asparagus as a potential source of linoleic and linolenic acid - a precursor for EPA and DHA. For this reason we analyzed fifty seven samples of asparagus collected from the local market. We used AOAC 996.06 method and analyses were performed with gas chromatograph with flame-ionization detector (GC-FID. The highest concentration of fatty acid in the asparagus was linoleic acid (C18:2n6 which content in asparagus is 25.620±1.0%. Also, asparagus is good source of -linolenic fatty acid (C18:3n3 and content of this fatty acid in asparagus is 8.840±0.3%. The omega-6 to omega-3 (n6/n3 ratio in asparagus was 3.19. Polyunsaturated fatty acids (PUFAs were higher than monounsaturated fatty acids (MUFAs, and from saturated fatty acids, palmitic acid was most frequent with 24.324±1.0%. From our study we can conclude that asparagus is very good source of unsaturated fatty acids, especially linoleic and linolenic fatty acids.

  16. Determining Phthalic Acid Esters Using Terahertz Time Domain Spectroscopy

    Science.gov (United States)

    Liu, L.; Shen, L.; Yang, F.; Han, F.; Hu, P.; Song, M.

    2016-09-01

    In this report terahertz time domain spectroscopy (THz-TDS) is applied for determining phthalic acid esters (PAEs) in standard materials. We reported the THz transmission spectrum in the frequency range of 0.2 to 2.0 THz for three PAEs: di-n-butyl phthalate (DBP), di-isononyl phthalate (DINP), and di-2-ethylhexyl phthalate ester (DEHP). The study provided the refractive indices and absorption features of these materials. The absorption spectra of three PAEs were simulated by using Gaussian software with Density Functional Theory (DFT) methods. For pure standard PAEs, the values of the refractive indices changed between 1.50 and 1.60. At 1.0 THz, the refractive indices were 1.524, 1.535, and 1.563 for DINP, DEHP, and DBP, respectively. In this experiment different concentrations of DBP were investigated using THz-TDS. Changes were measured in the low THz frequency range for refractive indices and characteristic absorption. The results indicated that THz-TDS is promising as a new method in determining PAEs in many materials. The results of this study could be used to support the practical application of THz-TDS in quality detection and food monitoring. In particular, this new technique could be used in detecting hazardous materials and other substances present in wine or foods.

  17. Densitometric determination of urinary 4-hydroxy-3-methoxymandelic acid (vanillylmandelic acid).

    Science.gov (United States)

    Agbaba, D; Stojanov, M; Rajacic, S; Zivanov-Stakic, D; Majkic-Singh, N

    1993-12-01

    We propose a simple and precise densitometric method for measuring vanillylmandelic acid (VMA). The method comprises direct urine application, thin-layer chromatographic (TLC) separation, postchromatographic derivatization, and in situ reading of the formed derivative at 560 nm. Quantitation was done by measuring peak area with a computer-controlled TLC Scanner and applying a five-point calibration function. The calibration function was 7.57-49.23 mumol/L. This method was used to determine urinary concentrations of excreted VMA; concentrations ranged from 4.84 to 56.06 mumol/day.

  18. Simultaneous determination of ascorbic acid, dopamine and uric acid based on tryptophan functionalized graphene

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Qianwen; He, Zhifang; He, Qian; Luo, Ai; Yan, Kaiwang; Zhang, Dongxia [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Geography and Environment Science, Northwest Normal University, Lanzhou, 730070 (China); Lu, Xiaoquan, E-mail: Luxq@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070 (China); Zhou, Xibin, E-mail: zhouxb@nwnu.edu.cn [Key Laboratory of Bioelectrochemistry and Environmental Analysis of Gansu Province, College of Geography and Environment Science, Northwest Normal University, Lanzhou, 730070 (China)

    2014-05-01

    Highlights: • Trp-GR was synthesized by utilizing a facile ultrasonic method. • The material as prepared had well dispersivity in water and better conductivity than pure GR. • Trp-GR/GCE showed excellent potential for the determination of AA, DA and UA. • The proposed method was applied for the analysis of AA, DA and UA in real samples. - Abstract: A new type of tryptophan-functionalized graphene nanocomposite (Trp-GR) was synthesized by utilizing a facile ultrasonic method via π–π conjugate action between graphene (GR) and tryptophan (Trp) molecule. The material as prepared had well dispersivity in water and better conductivity than pure GR. The surface morphology of Trp-GR was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA), and uric acid (UA) were investigated by cyclic voltammetry (CV) on the surface of Trp-GR. The separation of the oxidation peak potentials for AA–DA, DA–UA and UA–AA was about 182 mV, 125 mV and 307 mV, which allowed simultaneously determining AA, DA, and UA. Differential pulse voltammetery (DPV) was used for the determination of AA, DA, and UA in their mixture. Under optimum conditions, the linear response ranges for the determination of AA, DA, and UA were 0.2–12.9 mM, 0.5–110 μM, and 10–1000 μM, with the detection limits (S/N = 3) of 10.09 μM, 0.29 μM and 1.24 μM, respectively. Furthermore, the modified electrode was investigated for real sample analysis.

  19. Novel graphene flowers modified carbon fibers for simultaneous determination of ascorbic acid, dopamine and uric acid.

    Science.gov (United States)

    Du, Jiao; Yue, Ruirui; Ren, Fangfang; Yao, Zhangquan; Jiang, Fengxing; Yang, Ping; Du, Yukou

    2014-03-15

    A novel and sensitive carbon fiber electrode (CFE) modified by graphene flowers was prepared and used to simultaneously determine ascorbic acid (AA), dopamine (DA) and uric acid (UA). SEM images showed that beautiful and layer-petal graphene flowers homogeneously bloomed on the surface of CFE. Moreover, sharp and obvious oxidation peaks were found at the obtained electrode when compared with CFE and glassy carbon electrode (GCE) for the oxidation of AA, DA and UA. Also, the linear calibration plots for AA, DA and UA were observed, respectively, in the ranges of 45.4-1489.23 μM, 0.7-45.21 μM and 3.78-183.87 μM in the individual detection of each component. By simultaneously changing the concentrations of AA, DA and UA, their oxidation peaks appeared at -0.05 V, 0.16 V and 2.6 V, and the good linear responses ranges were 73.52-2305.53 μM, 1.36-125.69 μM and 3.98-371.49 μM, respectively. In addition, the obtained electrode showed satisfactory results when applied to the determination of AA, DA and UA in urine and serum samples.

  20. Quantitative Determination of Citric and Ascorbic Acid in Powdered Drink Mixes

    Science.gov (United States)

    Sigmann, Samuella B.; Wheeler, Dale E.

    2004-01-01

    A procedure by which the reactions are used to quantitatively determine the amount of total acid, the amount of total ascorbic acid and the amount of citric acid in a given sample of powdered drink mix, are described. A safe, reliable and low-cost quantitative method to analyze consumer product for acid content is provided.

  1. Determination of the dissociation constants of polyepoxysuccinic acid

    Institute of Scientific and Technical Information of China (English)

    Lihua ZHANG; Zhiliang ZHU; Yanling QIU; Ronghua ZHANG; Jianfu ZHAO

    2008-01-01

    The dissociation constants of polyepoxysucci-nic acid (PESA) were investigated in this study. Based on the potentiometric titration and the BEST program, the dissociation constants of PESA were determined. Considering the complexity of the dissociation of PESA in aqueous solution, several models were constructed to simulate the dissociation process of PESA. By compar-ison, the dissociation constants of PESA were obtained with model 4. The species distribution of PESA in aque-ous solution as a function of pH was also presented according to the experimental and calculation results. It showed that the H2L model with five basic structure units to describe the dissociation of PESA was reasonable, and the relevant constants had less error and better matching between the experimental and calculation data. The cor-responding values of pKai were 4.68 and 4.92, respectively, for H2L at 35℃ with ionic strength of 0.1 mol/L.

  2. Method for determining microamounts of uranium in solutions from copper ores, by liquid-liquid extraction and spectrophotometry with arsenazo III.; Metodo para determinar microcantidades de uranio en disoluciones de minerales de cobre, por extraccion liquido-liquido y espectrofotometria con arsenazo III

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, B.

    1972-07-01

    A spectrophotometric method is described for determining small amounts of uranium in aqueous solutions from copper ores. Uranium is quantitatively separated in a single extraction by a solution of tri-n-octylphosphine oxide in benzene, using ethylendiaminetetracetic acid and sodium fluoride as complexing agents, for improving the selectivity of the procedure. An aliquot of the extract is diluted with a hydrocolloidal solution of arsenazo III. Optical density is measured at 650 nm. (Author) 3 refs.

  3. Gallic Acid: Review of the Methods of Determination and Quantification.

    Science.gov (United States)

    Fernandes, Felipe Hugo Alencar; Salgado, Hérida Regina Nunes

    2016-05-03

    Gallic acid (3,4,5 trihydroxybenzoic acid) is a secondary metabolite present in most plants. This metabolite is known to exhibit a range of bioactivities including antioxidant, antimicrobial, anti-inflammatory, and anticancer. There are various methods to analyze gallic acid including spectrometry, chromatography, and capillary electrophoresis, among others. They have been developed to identify and quantify this active ingredient in most biological matrices. The aim of this article is to review the available information on analytical methods for gallic acid, as well as presenting the advantages and limitations of each technique.

  4. New method for the determination of bile acid turnover using /sup 75/Se-homocholic acid taurine

    Energy Technology Data Exchange (ETDEWEB)

    Delhez, H.; Meerwaldt, J.H.; van den Berg, J.W.O.; van Blankenstein, M.

    1982-06-01

    The introduction of /sup 75/Se-homocholic acid taurine (/sup 75/SeHCAT) greatly facilitates the investigation of diarrhoea of unknown origin. By using gamma-labelled bile acids, daily faecal bile acid loss can be measured in total collected stools, thus circumventing laborious mixing and sampling. The /sup 75/SeHCAT method proved to be reliable for the determination of bile acid turnover, giving results identical to the established turnover method using /sup 14/C-taurocholic acid. The new method however, is simpler and faster.

  5. Simultaneous Determination Method of Epoxyeicosatrienoic Acids and Dihydroxyeicosatrienoic Acids by LC-MS/MS System.

    Science.gov (United States)

    Mukai, Yuji; Toda, Takaki; Takeuchi, Satoya; Senda, Asuna; Yamashita, Miki; Eliasson, Erik; Rane, Anders; Inotsume, Nobuo

    2015-01-01

    Epoxyeicosatrienoic acids (EETs) are produced primarily by CYPs from arachidonic acid (AA) and then further metabolized to the corresponding dihydroxyeicosatrienoic acids (DHETs). EETs play important roles in physiological processes such as regulating vasodilation and inflammation. Thus, the drug inhibition of CYP-mediated AA metabolism could reduce production of EETs, potentially resulting in adverse cardiovascular events. The aim of this study was to develop a simple method to simultaneously determine the concentrations of both EETs and DHETs using a conventional LC-MS/MS system to evaluate drug-endogenous substance interactions, including eicosanoids. Eight eicosanoids (5,6-EET, 8,9-EET, 11,12-EET, 14,15-EET, 5,6-DHET, 8,9-DHET, 11,12-DHET, and 14,15-DHET) were detected with their corresponding deuterium-labeled eicosanoids as internal standards. The samples were purified by solid-phase extraction columns. Liquid chromatographic separation was achieved on a C18 column. DHETs and EETs were eluted at 4-7 and 18-26 min, respectively. The weighted (1/y(2)) calibration curves were linear over a range of 5-2000 nmol/L for EETs and 2-2000 nmol/L for DHETs. In quality control (QC) samples, the recoveries of eicosanoids were 95.2-118%. The intra-day precisions were within 6% in all three QC samples, and the inter-day precisions were eicosanoid levels in samples from incubation studies of AA by using human recombinant CYP enzyme (rCYP), and confirmed that the method has sensitivity sufficient for assessment of rCYP incubation study.

  6. Amino acid determination in some edible Mexican insects.

    Science.gov (United States)

    Ladrón de Guevara, O; Padilla, P; García, L; Pino, J M; Ramos-Elorduy, J

    1995-06-01

    The amino acid contents of edible insects from different provinces of Mexico and reference proteins were analysed by reversed-phase high-performance liquid chromatography and ion exchange chromatography. The insect amino acid contents were higher than the adult requirements indicated by the WHO/FAO pattern.

  7. Influence of educational level on determinants of folic acid use

    NARCIS (Netherlands)

    Pal-de Bruin, K.M. van der; Walle, H.E.K. de; Rover, C.M. de; Jeeninga, W.; Cornel, M.C.; Jong-van den Berg, L.T.W. de; Buitendijk, S.E.; Paulussen, T.G.W.M.

    2003-01-01

    In The Netherlands, periconceptional folic acid use to prevent neural tube defects was promoted through a national 'Folic Acid Campaign'. In two regions, a local campaign supplemented the national campaign to increase the chances of reaching women with low socio-economic status (SES). A framework of

  8. Determinants of Serum Glycerophospholipid Fatty Acids in Cystic Fibrosis

    Science.gov (United States)

    Drzymała-Czyż, Sławomira; Krzyżanowska, Patrycja; Koletzko, Berthold; Nowak, Jan; Miśkiewicz-Chotnicka, Anna; Moczko, Jerzy A.; Lisowska, Aleksandra; Walkowiak, Jarosław

    2017-01-01

    The etiology of altered blood fatty acid (FA) composition in cystic fibrosis (CF) is understood only partially. We aimed to investigate the determinants of serum glycerophospholipids’ FAs in CF with regard to the highest number of FAs and in the largest cohort to date. The study comprised 172 CF patients and 30 healthy subjects (HS). We assessed Fas’ profile (gas chromatography/mass spectrometry), CF transmembrane conductance regulator (CFTR) genotype, spirometry, fecal elastase-1, body height and weight Z-scores, liver disease, diabetes and colonization by Pseudomonas aeruginosa. The amounts of saturated FAs (C14:0, C16:0) and monounsaturated FAs (C16:1n-7, C18:1n-9, C20:1n-9, C20:3n-9) were significantly higher in CF patients than in HS. C18:3n-6, C20:3n-6 and C22:4n-6 levels were also higher in CF, but C18:2n-6, C20:2n-6 and C20:4n-6, as well as C22:6n-3, were lower. In a multiple regression analysis, levels of seven FAs were predicted by various sets of factors that included age, genotype, forced expiratory volume in one second, pancreatic status and diabetes. FA composition abnormalities are highly prevalent in CF patients. They seem to be caused by both metabolic disturbances and independent clinical risk factors. Further research into the influence of CFTR mutations on fat metabolism and desaturases’ activity is warranted. PMID:28106773

  9. Bile Acid Determination after Standardized Glucose Load in Pregnant Women

    Science.gov (United States)

    Adams, April; Jacobs, Katherine; Vogel, Rachel Isaksson; Lupo, Virginia

    2015-01-01

    Objective Intrahepatic cholestasis of pregnancy (ICP) is a rare liver disorder, usually manifesting in the third trimester and associated with increased perinatal morbidity and mortality. The hallmark laboratory abnormality in ICP is elevated fasting serum bile acids; however, there are limited data on whether a nonfasting state affects a pregnant woman's total bile acids. This study assesses fasting and nonfasting bile acid levels in 10 healthy pregnant women after a standardized glucose load to provide insight into the effects of a glucose load on bile acid profiles. Study Design Pilot prospective cohort analysis of serum bile acids in pregnant women. A total of 10 healthy pregnant women from 28 to 32 weeks' gestation were recruited for the study before undergoing a glucose tolerance test. Total serum bile acids were collected for each subject in the overnight fasting state, and 1 and 3 hours after the 100-g glucose load. Results There was a statistically significant difference between fasting versus 3-hour values. There was no statistically significant difference between fasting versus 1-hour and 1-hour versus 3-hour values. Conclusion There is a difference between fasting and nonfasting total serum bile acids after a 100-g glucose load in healthy pregnant women. PMID:26495178

  10. Simple and fast chromatographic method for the simultaneous determination of vanillylmandelic acid and homovanillic acid in human urine.

    Science.gov (United States)

    Zilli, M A

    1991-10-04

    A high-performance liquid chromatographic method for the determination of vanillylmandelic acid and homovanillic acid is described. The method is fast despite the great polarity differences between the two acids. Moreover the sample pretreatment is quick and it does not need complex or expensive equipment. The only requirement is the disposition of two pumps (or at least two eluent reservoirs) operated alternatively by means of a switching valve placed before the injection device. This makes the method available for most routine laboratories.

  11. QUANTITATIVE DETERMINATION OF SIALIC ACID IN INDIAN MILK AND MILK PRODUCTS

    OpenAIRE

    D.Karunanithi; V.M.Biju; A.Radhakrishna

    2013-01-01

    Background: Sialic acids are acidic sugars with a 9-carbon backbone, expressed as terminal residue on mammalian glycoconjugates. Sialic acid was found in two forms as N-acetylneuraminic acid (Neu5Ac) and N-Glycolylneuraminic acid (Neu5Gc) in meat and milk products. Neu5Ac is important for the brain and neuro development while Neu5Gc is suspected as human carcinogen. There is no data reported on sialic acid content in Indian milk and milk based products. Objective: To determine sialic acid (Ne...

  12. The application of hydrogen-palladium electrode for potentiometric acid-base determinations in tetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Jokić Anja B.

    2013-01-01

    Full Text Available The application of the hydrogen-palladium electrode (H2/Pd as the indicator electrode for the determination of relative acidity scale (Es, mV of tetrahydrofuran (THF and the potentiometric titrations of acids in this solvent was investigated. The relative acidity scale tetrahydrofuran was determined from the difference half-neutralization potentials of perchloric acid and tetrabutylammonium hydroxide (TBAH, which were measured by using both H2/Pd-SCE and glass-SCE electrode pairs. The experimentally obtained value of Es scale THF with a H2/Pd-SCE electrode pair was 1155 mV, and those obtained with glass-SCE electrode pair 880 mV. By using a H2/Pd indicator electrode, the individual acids (benzoic acid, palmitic acid, maleic acid, acetyl acetone, α-naphthol and two component acid mixtures (benzoic acid + α-naphthol, palmitic acid + α-naphthol, maleic acid + α-naphthol and maleic acid + ftalic acid were titrated with a standard solution of TBAH. In addition, sodium methylate and potassium hydroxide proved to be very suitable titrating agents for titrating of the individual acids and the acids in mixtures, respectively. The relative error of the determination of acids in mixture was less than 3%. The results are in agreement with those obtained by a conventional glass electrode. The advantages of H2/Pd electrode over a glass electrode in potentiometric acid-base determinations in tetrahydrofuran lie in the following: this electrode gives wider relative acidity scale THF, higher the potential jumps at the titration end-point and relatively fast response time; furthermore, it is very durable, simple to prepare and can be used in the titrations of small volumes. [Projekat Ministarstva nauke Republike Srbije, br.172051

  13. Fatty acids determination in Bronte pistachios by gas chromatographic method.

    Science.gov (United States)

    Pantano, Licia; Lo Cascio, Giovanni; Alongi, Angelina; Cammilleri, Gaetano; Vella, Antonio; Macaluso, Andrea; Cicero, Nicola; Migliazzo, Aldo; Ferrantelli, Vincenzo

    2016-10-01

    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.

  14. Fluorometric determination of inulin using 5-quinolineboronic acid and inulinase

    OpenAIRE

    力田, 正大; 江川, 祐哉; 関, 俊暢

    2012-01-01

    Inulin is a polysaccharide composed mainly of d-fructose units and is the most reliable indicator of the glomerular filtration rate. We have proposed an inulin detection method that involves the hydrolysis of inulin to d-fructose using inulinase and the selective binding of d-fructose from inulin using 5-quinolineboronic acid. In this method, the fluorescence of 5-quinolineboronic acid increases, depending on inulin concentration. For inulin in plasma, the detection and quantitation limits we...

  15. Obvladovanje kakovosti montaže pesta z metodo Poka Yoke

    OpenAIRE

    Lipuš, Mitja

    2012-01-01

    Diplomsko delo opisuje postopek iskanja najprimernejše rešitve preverjanja utora na pestu za homokinetični zglob in izdelavo kontrolne naprave. Z izbrano rešitvijo smo želeli vplivati na zmanjšanje reklamacij, katerih posledica so tudi manjši stroški in zvišanje produktivnost podjetja. Za obvladovanja kakovosti smo izbrali metodo »POKA YOKE«, ki preprečuje naključne napake, s predhodno metodo analiz možnih napak in posledic (FMEA). V diplomskem delu so predstavljene tudi ostale možnosti celo...

  16. Influence of educational level on determinants of folic acid use.

    Science.gov (United States)

    van der Pal-de Bruin, Karin M; de Walle, Hermien E K; de Rover, Carolien M; Jeeninga, Wendy; Cornel, Martina C; de Jong-van den Berg, Lolkje T W; Buitendijk, Simone E; Paulussen, Theo G W M

    2003-07-01

    In The Netherlands, periconceptional folic acid use to prevent neural tube defects was promoted through a national 'Folic Acid Campaign'. In two regions, a local campaign supplemented the national campaign to increase the chances of reaching women with low socio-economic status (SES). A framework of outcome criteria, defined as awareness knowledge, perceived safety, attitudes and subjective norms, was developed to evaluate the effectiveness of the two local campaigns. Data were gathered by means of two cross-sectional studies conducted just before and 1 year after the campaigns took place. Before the campaigns were conducted, there were already differences in all effect criteria and folic acid use between women of different educational levels, mostly in favour of women with a high level of education. Although both educational campaigns appeared to have a positive impact on all outcome criteria, they failed to reduce the existing differences in these outcome criteria between women of different educational levels. Folic acid use can be promoted effectively by mass media campaigns, certainly in a large group of women with no prior knowledge of the health benefits associated with periconceptional folic acid use. However, in order to achieve more equal health outcomes among women of low and high SES, it seems that more tailored interventions for women of low SES are needed.

  17. Using Conductivity Measurements to Determine the Identities and Concentrations of Unknown Acids: An Inquiry Laboratory Experiment

    Science.gov (United States)

    Smith, K. Christopher; Garza, Ariana

    2015-01-01

    This paper describes a student designed experiment using titrations involving conductivity measurements to identify unknown acids as being either HCl or H[subscript 2]SO[subscript 4], and to determine the concentrations of the acids, thereby improving the utility of standard acid-base titrations. Using an inquiry context, students gain experience…

  18. [Determination of arsanilic acid and sulfanilic acid as adulterant in feed additives by reversed-phase high performance liquid chromatography].

    Science.gov (United States)

    Xu, Jinping; He, Heng; Xu, Mengyi; Qu, Yanhua

    2010-02-01

    A reversed-phase high performance liquid chromatographic (RP-HPLC) method was established for the determination of arsanilic acid and sulfanilic acid as adulterant in the feed additives. The separation was carried out on a Waters Bondapak C18 column, and methanol-water (pH 2.9 adjusted by 0.01 mol/L phosphoric acid) (1 : 4, v/v) was used as the mobile phase with a flow rate of 1.0 mL/min. A diode array detector was used at 244 nm as the detection wavelength. Arsanilic acid and sulfanilic acid were separated within 3 min. The linear ranges all were 5 - 200 mg/L and the detection limits (S/N = 3) were 0.20 and 0.15 mg/L for arsanilic acid and sulfanilic acid, respectively. This method is simple and rapid, and suitable for the simultaneous determination of arsanilic acid and sulfanilic acid in feed additives.

  19. Determination of polyfluoroalkyl phosphoric acid diesters, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, perfluoroalkyl carboxylic acids, and perfluoroalkane sulfonic acids in lake trout from the Great Lakes region.

    Science.gov (United States)

    Guo, Rui; Reiner, Eric J; Bhavsar, Satyendra P; Helm, Paul A; Mabury, Scott A; Braekevelt, Eric; Tittlemier, Sheryl A

    2012-11-01

    A comprehensive method to extract perfluoroalkyl carboxylic acids, perfluoroalkane sulfonic acids, perfluoroalkyl phosphonic acids, perfluoroalkyl phosphinic acids, and polyfluoroalkyl phosphoric acid diesters simultaneously from fish samples has been developed. The recoveries of target compounds ranged from 78 % to 121 %. The new method was used to analyze lake trout (Salvelinus namaycush) from the Great Lakes region. The results showed that the total perfluoroalkane sulfonate concentrations ranged from 0.1 to 145 ng/g (wet weight) with perfluorooctane sulfonate (PFOS) as the dominant contaminant. Concentrations in fish between lakes were in the order of Lakes Ontario ≈ Erie > Huron > Superior ≈ Nipigon. The total perfluoroalkyl carboxylic acid concentrations ranged from 0.2 to 18.2 ng/g wet weight. The aggregate mean perfluorooctanoic acid (PFOA) concentration in fish across all lakes was 0.045 ± 0.023 ng/g. Mean concentrations of PFOA were not significantly different (p > 0.1) among the five lakes. Perfluoroalkyl phosphinic acids were detected in lake trout from Lake Ontario, Lake Erie, and Lake Huron with concentration ranging from non-detect (ND) to 0.032 ng/g. Polyfluoroalkyl phosphoric acid diesters were detected only in lake trout from Lake Huron, at levels similar to perfluorooctanoic acid.

  20. Response of Substituted Indoleacetic Acids in the Indolo-alpha-pyrone Fluorescence Determination

    DEFF Research Database (Denmark)

    Engvild, Kjeld Christensen; Böttger, M.; Kaiser, P.

    1978-01-01

    .-pyrones. Other halogenated indoleacetic acids show between zero and 60% of the fluorescence of IAA. Apparently the concentration of IAA cannot be determined in crude extracts in the presence of 4-chloro- or 5-hydroxy-indoleacetic acid, because separate determinations of each of these compounds are not possible......The method of indolo-.alpha.-pyrone fluorescence-determination of IAA was investigated to study possible interference from 4-chloro-indoleacetic acid and 5-hydroxyindoleacetic acid, which occur naturally. Both compounds show about 40% of the fluorescence of IAA after conversion into their .alpha...

  1. Determination of Enantiomeric Excess of Glutamic Acids by Lab-made Capillary Array Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Jun WANG; Kai Ying LIU; Li WANG; Ji Ling BAI

    2006-01-01

    Simulated enantiomeric excess of glutamic acid was determined by a lab-made sixteen-channel capillary array electrophoresis with confocal fluorescent rotary scanner. The experimental results indicated that the capillary array electrophoresis method can accurately determine the enantiomeric excess of glutamic acid and can be used for high-throughput screening system for combinatorial asymmetric catalysis.

  2. Flow measurement in a 170-MW hydraulic turbine using the Gibson method; Medicion del flujo de una turbina hidraulica de 170 MW utilizando el metodo Gibson

    Energy Technology Data Exchange (ETDEWEB)

    Urquiza, Gustavo [Universidad Autonoma del Estado de Morelos (Mexico); Adamkowski, Adam [The Szewalski Institute of Fluid-Flow Machinery (Poland); Kubiak, Janusz; Sierra, Fernando [Universidad Autonoma del Estado de Morelos (Mexico); Janicki, Waldemar [The Szewalski Institute of Fluid-Flow Machinery (Poland); Fernandez, J. Manuel [Comision Federal de Electricidad (Mexico)

    2007-07-15

    This paper describes the methodology applied for measuring water flow through a 170-MW hydraulic turbine. The flow rate was measured using the pressure-time method, also known as the Gibson method. This method uses the well-known water hammer phenomenon in pipelines; in turbine penstocks, for instance. The version of this method used here is based on measuring, during total stop of the water stream, the time-history of pressure change in one section of the turbine penstock and relate it to the pressure in the upper reservoir to which the penstock is connected. The volumetric flow rate is determined from the relevant integration of the measured temporary pressure rise. Flow measurement was possible this way because the influence of the penstock inlet was negligible as far as an error of the measurement is concerned. The length of the penstock was 300 m. Previous experience and a standard IEC-41-1991 were the criteria adopted and applied. A fast and efficient acquisition system, including a 16 bit card, was used. The flow rate was calculated using a computer program developed and tested on several cases. The results obtained with the Gibson method were used for calibration of the on-line flow measuring system based on the Winter-Kennedy method as one of the index methods. This method is very often used for continuous monitoring of the flow rate through hydraulic turbines, when the calibration has been done on site by using the results of measurements obtained by the absolute method. Having measured the flow rate and output power, the efficiency was calculated for any operating conditions. A curve showing the best operating conditions based on the highest efficiency is presented and discussed. The details of the instrumentation, its installation, and the results obtained are discussed in the paper. [Spanish] Este articulo describe la metodologia aplicada para la medicion del flujo en una turbina hidraulica de 170 MW. El flujo se midio utilizando el metodo de presion

  3. Probing the Specificity Determinants of Amino Acid Recognition by Arginase

    Energy Technology Data Exchange (ETDEWEB)

    Shishova, E.; Di Costanzo, L; Emig, F; Ash, D; Christianson, D

    2009-01-01

    Arginase is a binuclear manganese metalloenzyme that serves as a therapeutic target for the treatment of asthma, erectile dysfunction, and atherosclerosis. In order to better understand the molecular basis of inhibitor affinity, we have employed site-directed mutagenesis, enzyme kinetics, and X-ray crystallography to probe the molecular recognition of the amino acid moiety (i.e., the ?-amino and ?-carboxylate groups) of substrate l-arginine and inhibitors in the active site of arginase I. Specifically, we focus on (1) a water-mediated hydrogen bond between the substrate ?-carboxylate and T135, (2) a direct hydrogen bond between the substrate ?-carboxylate and N130, and (3) a direct charged hydrogen bond between the substrate ?-amino group and D183. Amino acid substitutions for T135, N130, and D183 generally compromise substrate affinity as reflected by increased KM values but have less pronounced effects on catalytic function as reflected by minimal variations of kcat. As with substrate KM values, inhibitor Kd values increase for binding to enzyme mutants and suggest that the relative contribution of intermolecular interactions to amino acid affinity in the arginase active site is water-mediated hydrogen bond < direct hydrogen bond < direct charged hydrogen bond. Structural comparisons of arginase with the related binuclear manganese metalloenzymes agmatinase and proclavaminic acid amidinohydrolase suggest that the evolution of substrate recognition in the arginase fold occurs by mutation of residues contained in specificity loops flanking the mouth of the active site (especially loops 4 and 5), thereby allowing diverse guanidinium substrates to be accommodated for catalysis.

  4. Use of ionic chromatography in determining the contamination of apple juice by lactic acid.

    Science.gov (United States)

    Wojtczak, M; Antczak, A; Przybyt, M

    2010-06-01

    High-performance anion exchange chromatography (HPAEC) with conductometric detection was used for the determination of the lactic acid content of apple juice subjected to fermentation with the strains of Lactobacillus brevis and Lactobacillus plantarum, obtained from a collection, at 20 and 30 degrees C. At the same time, lactate content was determined by means of enzymatic tests and biosensors. Lactic acid concentrations determined by the chromatographic method are similar to those obtained during analysis by enzymatic tests. However, acid concentrations determined by means of biosensors substantially diverge from these results.

  5. A study on antimony determination in environmental samples by neutron activation analysis: validation of the methodology and determination of the uncertainty of the measurement; Estudo sobre a determinacao de antimonio em amostras ambientais pelo metodo de analise por ativacao com neutrons: validacao da metodologia e determinacao da incerteza da medicao

    Energy Technology Data Exchange (ETDEWEB)

    Matsubara, Tassiane Cristina Martins

    2011-07-01

    Antimony is an element found in low concentrations in the environment. However, its determination has attracted great interest due to the knowledge of its toxicity and increasing application in industry. The determination of antimony has been a challenge for researchers since this element is found in low concentrations which make its analysis a difficult task. Therefore, although neutron activation analysis (NAA) is an appropriate method for the determination of various elements in different types of matrix, in the case of Sb its analysis presents some difficulties, mainly due to spectral interferences. The objective of this research was to validate the NAA method for Sb determination in environmental samples. To establish appropriate conditions for Sb determinations, preliminary assays were carried out for further analysis of certified reference materials (CRM). The experimental procedure was to irradiate samples with a synthetic Sb standard for a period of 8 or 16 hours in the IEA-R1 nuclear research reactor, followed by gamma ray spectrometry. The quantification of Sb was performed by measuring the radioactive isotopes of {sup 122}Sb and '1{sup 24}Sb. The results of preliminary assays indicated the presence of Sb in Whatman no 40 filter paper used in the preparation of the synthetic standard, but at very low concentrations, which could be considered negligible. In the case of the plastic material used in bags for the sample irradiation, it should be chosen carefully, because depending on the thickness, they may contain Sb. The analyses of the stability of the diluted Sb standard solution showed no change in the Sb concentration within eight months after its preparation. Results obtained in the analysis of certified reference materials indicated the interference of {sup 76}As and also of {sup 134}Cs and {sup 152}Eu in the Sb determinations by measuring '1{sup 22}Sb, due to the proximity of the gamma ray energies. The high activity of '2{sup 4}Na

  6. GIUSEPPE DE ROSA, Metodo per pianisti accompagnatori della danza, Milano, Suvini Zerboni, 2010

    Directory of Open Access Journals (Sweden)

    Chiara Sintoni

    2014-12-01

    Full Text Available Il volume di Giuseppe De Rosa è al contempo un agile metodo teorico-pratico per la formazione del pianista accompagnatore della danza classica e un sussidio didattico per la sua attività in situazione. Frutto dell’esperienza pluriennale dell’autore, colma un vuoto nella pubblicistica italiana dedicata all’argomento.

  7. DETERMINATION OF CARBOXYLIC ACIDS BY ION-EXCLUSION CHROMATOGRAPHY WITH NON-SUPPRESSED CONDUCTIVITY AND OPTICAL DETECTORS

    Science.gov (United States)

    Determination of carboxylic acids using non-suppressed conductivity and UV detections is described. The background conductance of 1-octanesulfonic acid, hexane sulfonic acid and sulfuric acid at varying concentrations was determined. Using 0.2 mM 1-octanesulfonic acid as a mobile...

  8. Delphinidin immobilized on silver nanoparticles for the simultaneous determination of ascorbic acid, noradrenalin, uric acid, and tryptophan

    Directory of Open Access Journals (Sweden)

    Navid Nasirizadeh

    2016-04-01

    Full Text Available In the present study, the fabrication of a new modified electrode for electrocatalytic oxidation of noradrenalin, based on the delphinidin immobilized on silver nanoparticles modified glassy carbon electrode. Cyclic voltammetry was used to investigate the redox properties of this modified electrode. The surface charge transfer rate constant (ks and the charge transfer coefficient (α for the electron transfer between the glassy carbon electrode and the immobilized delphinidin were calculated. The differential pulse voltammetry exhibited two linear dynamic ranges and a detection limit of 0.40μM for noradrenalin determination. Moreover, the present electrode could separate the oxidation peak potentials of ascorbic acid, noradrenalin, uric acid, and tryptophan in a mixture. The usefulness of this nanosensor was also investigated for the determination of ascorbic acid, noradrenalin, and uric acid in pharmaceutical and biological fluid samples with satisfactory results.

  9. Determination of the Acid-Base Dissociation Constant of Acid-Degradable Hexamethylenetetramine by Capillary Zone Electrophoresis.

    Science.gov (United States)

    Takayanagi, Toshio; Shimakami, Natsumi; Kurashina, Masashi; Mizuguchi, Hitoshi; Yabutani, Tomoki

    2016-01-01

    The acid-base equilibrium of hexamethylenetetramine (hexamine) was analyzed with its effective electrophoretic mobility by capillary zone electrophoresis. Although hexamine is degradable in a weakly acidic aqueous solution, and the degraded products of ammonia and formaldehyde can be formed, the effective electrophoretic mobility of hexamine was measured in the pH range between 2.8 and 6.9. An acid-base dissociation equilibrium of the protonated hexamine was analyzed based on the mobility change, and an acid dissociation constant of pKa = 4.93 ± 0.01 (mean ± standard error, ionic strength: 0.020 mol dm(-3)) was determined. The monoprotic acid-base equilibrium of hexamine was confirmed through comparisons of its electrophoretic mobility with the N-ethylquinolinium ion and with the monocationic N-ethyl derivative of hexamine, as well as a slope analysis of the dissociation equilibrium.

  10. Occurrence and Determination of Haloacetic Acids in Metro Manila Drinking Water

    Directory of Open Access Journals (Sweden)

    Irene B. Rodriguez

    2009-12-01

    Full Text Available Haloacetic acids are found in chlorinated water with high organic matter content. An analytical method based on a US EPA method for measuring these compounds in water is described. The optimized method used diethyl ether as extraction solvent with sulphuric acid-methanol as esterification agent and subsequent detection by gas chromatography-electron capture detection. Evaluation of this method showed that it was linear in the concentration range of 10 to 150 µg L-1 and the method detection limits were from 17 to 57 µg L-1. Although the method demonstrated low recoveries (16 to 43%, it is useful in the quantitative determination of monochloroacetic acid as well as the qualitative determination of other haloacetic acids in water. Drinking water samples taken from different areas in Metro Manila serviced by the local treatment plants were analysed using the method. Monochloroacetic acid, monobromoacetic acid, and bromochloroacetic acid were detected in these samples. Monochloroacetic acid was quantified and found in concentrations ranging from 19 to 157 µg L-1. In most of the water samples, the concentration of monochloroacetic acid exceeded the US EPA maximum allowable total concentration of 60 µg L-1 for the five haloacetic acids (monochloro-, dichloro-, trichloro-, monobromo-, and dibromoacetic acids in drinking water. This initial study established the occurrence of potentially harmful haloacetic acids in the local drinking water supplies.

  11. Determination of Total Acid in Palygorskite Chemically Modified by N-Butylamine Thermodesorption

    Directory of Open Access Journals (Sweden)

    Ruiz Juan A.C.

    2002-01-01

    Full Text Available The acid properties of palygorskite clay (R1 were studied using n-butylamine as probe molecule. A comparison was made of these properties in palygorskite clay (R1, in an acidified palygorskite (R2 and in acid palygorskite loaded with 2% of lanthanum (R3. The total acid properties were determined by FTIR (Fourier Transform Infrared and TG-DTA (thermogravimetry. The acidity increased as follows: R3>R2>R1. The acid strength sites were classified as physisorbed, weak, medium and strong. The acid treatment did not change the site distribution, apparently only removing channel impurities. The introduction of lanthanum created many more acid sites and increased the specific area. Both weak and strong sites, which increased significantly, were considered new active acid sites produced by the lanthanum.

  12. Simultaneous determination of free amino acids in Pu-erh tea and their changes during fermentation.

    Science.gov (United States)

    Zhu, Yuchen; Luo, Yinghua; Wang, Pengpu; Zhao, Mengyao; Li, Lei; Hu, Xiaosong; Chen, Fang

    2016-03-01

    Pu-erh ripened tea is produced through a unique microbial fermentation process from the sun-dried leaves of large-leaf tea species (Camellia sinensis (Linn.) var. assamica (Masters) Kitamura) in Yunnan province of China. In this study, the changes of amino acid profiles during fermentation of Pu-erh tea were investigated, based on the improved HPLC-UV method with PITC pre-column derivatization for the simultaneous determination of twenty free amino acids. Results showed that aspartic acid, glutamic acid, arginine, alanine, theanine and tyrosine were the major amino acids in tea samples. Fermentation significantly influenced on the amino acid profiles. The total free amino acid contents significantly decreased during fermentation (pamino acids and acrylamide contents in Pu-erh ripened tea.

  13. Determination of nitrite ion and sulfanilic and orthanilic acids by differential pulse polarography

    Energy Technology Data Exchange (ETDEWEB)

    Sulaiman, S.T.

    1984-11-01

    The nitrite ion can be determined with a high degree of accuracy and sensitivity by differential pulse polarography utilizing the rapid and quantitative reaction between the nitrite ion and sulfanilic acid or orthanilic acid at pH 1.5. The experimental detection limit is shown to be 8.6 X 10/sup -8/ M (as NO/sub 2//sup -/) in simple aqueous solution. The method is further used to determine concentrations of sulfanilic acid down to 4 X 10/sup -7/ M and orthanilic acid down to 1.6 X 10/sup -6/ M under optimum conditions.

  14. Capillary gas-chromatographic determination of urinary homovanillic acid and vanillylmandelic acid.

    Science.gov (United States)

    Tuchman, M; Crippin, P J; Krivit, W

    1983-05-01

    This relatively simple, rapid method for quantification of homovanillic acid (HVA) and vanillylmandelic acid (VMA) involves solvent extraction and capillary gas chromatography. With use of this extraction method, the overall analytical recovery from an aqueous solution is 92.5% for HVA and 79.2% for VMA. 3,4-Dihydroxybenzoic acid is the internal standard. Minimal detectable quantities with this method are less than 1 mg/g of creatinine. Capillary gas chromatography produces a chromatogram that is superior to that of packed-column gas chromatography. We also report quantitative results for urinary HVA and VMA in neuroblastoma patients and in normal individuals, demonstrating the diagnostic value of this method.

  15. Quality control of herbs: determination of amino acids in Althaea officinalis, Matricaria chamomilla and Taraxacum officinale.

    Science.gov (United States)

    Qureshi, Muhammad Nasimullah; Stecher, Guenther; Bonn, Guenther Karl

    2014-05-01

    Analysis of raw materials and final products need reliable methods for the standardization of natural product drugs. Legal guideline also emphasizes on the qualitative and quantitative analyses of the plant constituents in an herbal product. In this study, thin layer chromatography (TLC) and amino acid analyzer was used for the determination of amino acids in plant extracts. Samples for this study were standards and aqueous extracts from Althaea officinalis, Matricaria chamomilla and Taraxacum officinale. Different amino acids in the extracts were detected through TLC. An automatic amino acid analyzer was used for the quantification of amino acids in the plant extracts under study.

  16. Determination of Nucleic Acid Hydration Using Osmotic Stress

    Science.gov (United States)

    Rozners, Eriks

    2010-01-01

    Understanding the role water plays in biological processes requires detailed knowledge of the phenomena of biopolymer hydration. Crystal structures have identified exact sites occupied by the water molecules in immediate hydration layers. NMR and molecular modeling have provided information on dynamics of water molecules occupying these sites. However, these studies give little information on the thermodynamic contribution of water molecules to conformational equilibria and recognition affinity. This unit describes probing of nucleic acid hydration using osmotic stress, a method that provides thermodynamic information complementary to crystallography, NMR and molecular modeling. Osmotic stress monitors the depression of melting temperature upon decreasing the water activity and calculates the number of thermodynamically unique water molecules associated with the double helix and released from the single strands upon melting. PMID:21154532

  17. Determination of peroxy radical-scavenging of lactic acid bacteria.

    Science.gov (United States)

    Stecchini, M L; Del Torre, M; Munari, M

    2001-02-28

    Responses of lactic acid bacteria (LAB) to peroxy radicals generated via thermal (40 degrees C) decomposition of the diazocompound 2,2,-azo-bis (2-amidinopropane) dihydrochloride (ABAP), were studied. In general, LAB displayed survival curves with shoulders and tails indicative of 'multihit' killing by exposure to peroxy radicals. One strain, Lactococcus lactis subsp. lactis DIP15, producing a slope of 0.0105 in the kinetic analysis when exposed to 4 mM ABAP, exhibited a measurable antioxidant capacity. The other LAB failed to show any significant antioxidant capacity. The antioxidant capacity of strain DIP15 remained constant after cells have been heat-treated, suggesting that compounds bearing free radical scavenging capacity are rather stable.

  18. Spectrofluorimetric determination of gallium with calon-carboxylic acid

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A simple and sensitive spectrofluorimetric procedure for the analysis of microquantities of gallium in alloy wasdescribed. The method is based on the formation of Ga(Ⅲ)-CCA (calon-carboxylic acid) complex. The emission of thefluorescent complex was measured at λ = 620 nm with excitation at λ = 584 nm. A good linearity was found in the galliumrange of 0.7-280 ng/mL. The precision of the method is good and the relative standard deviation is 1.9% for a gallium stan-dard solution of 70 ng/mL. The procedure was proved to be suitable in terms of accuracy and selectivity for the mi-croamount of gallium in alloy.

  19. [The determination of sialic acid in cancer patients].

    Science.gov (United States)

    Correale, M; Abbate, I; Gargano, G; Catino, A; Musci, M D; Dragone, C D; De Lena, M

    1992-01-01

    The availability of a new rapid and reproducible laboratory test led to an easy dosage of sialic acid (AS) serum levels in neoplastic patients. This substance, involved in tumoral transformation and metastatic spread, has been evaluated in 278 neoplastic patients: 183 patients were affected by lymphoma (96 NHL and 87 HD), 60 by breast cancer and 35 by lung cancer. All groups of patients considered showed mean values of AS higher than healthy controls and the positive percentages, compared with cut-off levels, were respectively: NHL 71%, HD 70%, breast cancer 38%, lung cancer 89%. Even if the low specificity of this marker limits its clinical validity, AS, that seems related to clinical course of disease, could be useful in the monitoring of many neoplasms.

  20. SIMULTANEOUS DETERMINATION OF CHLORINE DIOXIDE AND HYPOCHLOROUS ACID IN BLEACHING SYSTEM

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2011-04-01

    Full Text Available This study has demonstrated a rapid spectroscopic method for the determination of chlorine dioxide and hypochlorous acid concentrations in the pulp bleaching processes. It was found that chlorine dioxide and hypochlorous acid have an isosbestic wavelength of 295 nm. The soluble lignin in such a system is the main interference, but can be corrected by determining the absorbances at 295 nm, 380 nm, and 480 nm. Thus, based on the spectroscopic measurements at 295 nm (the isosbestic point wavelength for chlorine dioxide and hypochlorous acid, 380 nm (absorbance wavelength of chlorine dioxide and 480 nm (the acid soluble lignin absorbance wavelength, the chlorine dioxide and hypochlorous acid concentrations in the bleaching process can be quantified. However, hypochlorous acid was not detected in the real bleaching effluent for its low content. The present method is simple, rapid, accurate, and has the potential for on-line monitoring of the chlorine dioxide bleaching process.

  1. 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

    2003-01-01

    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.

  2. Determination of free medium-chain fatty acids in beer by stir bar sorptive extraction.

    Science.gov (United States)

    Horák, Tomás; Culík, Jirí; Jurková, Marie; Cejka, Pavel; Kellner, Vladimír

    2008-07-04

    Free medium-chain fatty acids in beer originate from raw materials, mainly from the fermentation activity of yeasts, and can influence beer taste, vitality of yeasts and also the foam stability of beer. This study presents the development of the method for the determination of free fatty medium-chain acids including caproic acid, caprylic acid, capric acid and lauric acid in beer or wort using stir bar sorptive extraction (SBSE). The combination of this extraction technique with solvent back extraction of the extracted analytes and subsequent gas chromatographic analysis with flame ionization detection was used for the determination of these compounds. The influences of different solvent back solutions, sampling time, solvent back extraction times and different contents of ethanol were studied. The method had high repeatability (RSD <6.7%), good linearity (the correlation coefficients were higher than 0.9963 for quadratic curves over the concentration range 0.5-8.0mg/l) and recoveries 57-89%.

  3. Determinants of cyanuric acid and melamine assembly in water.

    Science.gov (United States)

    Ma, Mingming; Bong, Dennis

    2011-07-19

    While the recognition of cyanuric acid (CA) by melamine (M) and their derivatives has been known to occur in both water and organic solvents for some time, analysis of CA/M assembly in water has not been reported (Ranganathan, A.; Pedireddi, V. R.; Rao, C. N. R. J. Am. Chem. Soc.1999, 121, 1752-1753; Mathias, J. P.; Simanek, E. E.; Seto, C. T.; Whitesides, G. M. Macromol. Symp.1994, 77, 157-166; Zerkowski, J. A.; MacDonald, J. C.; Seto, C. T.; Wierda, D. A.; Whitesides, G. M. J. Am. Chem. Soc.1994, 116, 2382-2391; Mathias, J. P.; Seto, C. T.; Whitesides, G. M. Polym. Prepr.1993, 34, 92-93; Seto, C. T.; Whitesides, G. M. J. Am. Chem. Soc.1993, 115, 905-916; Zerkowski, J. A.; Seto, C. T.; Whitesides, G. M. J. Am. Chem. Soc.1992, 114, 5473-5475; Seto, C. T.; Whitesides, G. M. J. Am. Chem. Soc.1990, 112, 6409-6411; Wang, Y.; Wei, B.; Wang, Q. J. Chem. Cryst.1990, 20, 79-84; ten Cate, M. G. J.; Huskens, J.; Crego-Calama, M.; Reinhoudt, D. N. Chem.-Eur. J.2004, 10, 3632-3639). We have examined assembly of CA/M, as well as assembly of soluble trivalent CA and M derivatives (TCA/TM), in aqueous solvent, using a combination of solution phase NMR, isothermal titration and differential scanning calorimetry (ITC/DSC), cryo-transmission electron microscopy (cryo-TEM), and synthetic chemistry. While the parent heterocycles coprecipitate in water, the trivalent system displays more controlled and cooperative assembly that occurs at lower concentrations than the parent and yields a stable nanoparticle suspension. The assembly of both parent and trivalent systems is rigorously 1:1 and proceeds as an exothermic, proton-transfer coupled process in neutral pH water. Though CA and M are considered canonical hydrogen-bonding motifs in organic solvents, we find that their assembly in water is driven in large part by enthalpically favorable surface-area burial, similar to what is observed with nucleic acid recognition. There are currently few synthetic systems capable of robust molecular

  4. The Determination of the pKaof Multiprotic, Weak Acids by Analyzing Potentiometric Acid Base Titration Data with Difference Plots

    Science.gov (United States)

    Kraft, Arno

    2003-05-01

    This paper discusses the pKa determination of mono-, di-, and triprotic weak acids with the help of difference (Bjerrum) plots, and the effect of strong acid base concentration errors, ligand weight errors, and nonlinear electrode response. Experimental examples are given for the titration of an acidic heterocycle, as well as glycine, ethylenediamine, and tris(2-aminoethyl)amine (the last two after addition of excess HCl to ensure complete protonation) with standarized NaOH. The analysis procedure makes use of Microsoft Excel spreadsheets and nonlinear least squares curve fitting of the experimental data to the theoretical Bjerrum function. In addition to providing pKa values for mono- and multiprotic acids, this approach has been found suitable for detecting small errors in parameters, such as strong acid and ligand concentration, and corrections can often become necessary to achieve the best fit. Difference plots allow the pKa values of monoprotic and multiprotic weak acids to be determined rapidly and with good precision.

  5. [Simultaneous determination of organic acids and saccharides in lactic acid fermentation broth from biomass using high performance liquid chromatography].

    Science.gov (United States)

    Ma, Rui; Ouyang, Jia; Li, Xin; Lian, Zhina; Cai, Cong

    2012-01-01

    Abstract: A high performance liquid chromatographic method for the simultaneous determination of organic acids and saccharides in lactic acid fermentation broth from biomass was developed. A Bio-Rad Aminex HPX-87H column was used at 55 degrees C. The mobile phase was 5 mmol/L sulfuric acid solution at a flow rate of 0.6 mL/min. The samples were detected by a refractive index detector (RID). The results showed that six organic acids and three saccharides in fermentation broth were completely separated and determined in 17 min. The linear correlation coefficients were above 0.999 8 in the range of 0.15-5.19 g/L. Under the optimized conditions, the recoveries of the organic acids and saccharides in Rhizopus oryzae fermentation broth at two spiked levels were in the range of 96.91%-103.11% with the relative standard deviations (RSDs, n = 6) of 0.81%-4.61%. This method is fast and accurate for the quantitative analysis of the organic acids and saccharides in microbial fermentation broths.

  6. Determination of thoracic and inhalable fraction of sulfuric acid(VI) in workplace air

    OpenAIRE

    Małgorzata Szewczyńska; Małgorzata Pośniak; Emilia Pągowska

    2016-01-01

    Background: The article presents the results of the determination of the inhalable and thoracic fraction of sulfuric acid(VI) in 3 workplaces producing or processing this chemical. Material and Methods: To collect thoracic fractions of sulfuric acid(VI) Parallel Particle Impactor (PPI) was used. To isolate inhalable fraction of sulfuric acid(VI) from the air we used a sampler developed at the Institute of Occupational Medicine (IOM), United Kingdom. Parallel Particle Impactor and IOM samplers...

  7. Determination of fruit characteristics, fatty acid profile and total antioxidant capacity of Mespilus germanica L. fruit

    Directory of Open Access Journals (Sweden)

    Hale Seçilmiş Canbay

    2015-11-01

    Full Text Available Objective: To determine fruit characteristics, fatty acid profile and total antioxidant capacitiy of first cultured Mespilus germanica L. Methods: A total of 15 fruits were taken randomly from four directions of adult trees. Then the physical and chemical properties of first cultured medlar fruit (Istanbul/Turkey were measured by using refractometer, colorimeter, spectrophotometer and gas chromatograph mass spectrometer, respectivly. Results: In the fruit studied, the results showed that palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid and behenic acid were the most abundant fatty acids (FAs, and the main FA was palmitic acid [(35.35 ± 1.20%]. The percentage of linoleic acid and stearic acid in this fruit oil were (29.10 ± 1.70% and (8.53 ± 0.25%, respectively. As a result of the analysis, the total antioxidant capacity of medlar fruit was (1.1 ± 0.2 mmol trolox equivalents/L. Conclusions: The present study has demonstrated the concentrations of FAs and the antioxidantive capacity of first cultured Istanbul medlar fruits by using many tested methods. It is proved that in our daily life, medlar fruit plays a significant role with its nutrition and health effect.

  8. Development of an Analytical System for Determination of Free Acid via a Joint Method Combining Density and Conductivity Measurement

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Determination of free acid plays an important role in spent nuclear fuel reprocessing. It is necessary to develop a rapid analytical device and method for measuring free acid. A novel analytical system and method was studied to monitor the acidity

  9. THE P-31-NMR SPECTROSCOPIC DETERMINATION OF THE ENANTIOMERIC EXCESS OF UNPROTECTED AMINO-ACIDS

    NARCIS (Netherlands)

    HULST, R; DEVRIES, NK; FERINGA, BL

    1992-01-01

    No separation is needed! The enantiomeric excess of unprotected amino acids can be determined very reliable by P-31 NMR spectroscopy after derivatization as phosphonic amides 1. This rapid and simple analytical procedure, suitable for aqueous solutions. is also applicable for amino acid derivatives,

  10. [Study on determination of caffeic acid, chlorogenic acid in rat plasma and their pharmacokinetics with LC-MS/MS].

    Science.gov (United States)

    Dai, Guo-Liang; Ma, Shi-Tang; Liu, Shi-Jia; Cheng, Xiao-Gui; Zang, Yu-Xin; Ju, Wen-Zheng; Tan, Heng-Shan

    2013-11-01

    To establish a LC-MS/MS method to determine caffeic acid, chlorogenic acid in rat plasma and study their pharmacokinetics in rats. Six Sprague-Dawley rats were intravenously injected with 4 mL x kg(-1) of Dengzhanxixin injection, respectively. Their drug plasma concentration was determined by LC-MS/MS, with tinidazole as an internal standard. The pharmacokinetic parameters were calculated by DAS 1.0. The linear concentration ranges of caffeic acid, and chlorogenic acid were 2-128 microg x L(-1) (r = 0.998 1) and 3-384 microg x L(-1) (r = 0.998 7), respectively. The methodological test showed conformance to the requirements. The intraday and inter-day variable coefficients were both less than 10.0%, indicating that both of legitimate precise and accuracy were in conformity with the requirements of biological sample analysis. For caffeic acid, the pharmacokinetic parameter t1/2beta AUC0-t, and CL were (130.91 +/- 38.77) min, (4.89 +/- 0.96) mg x min x L(-1) and (0.12 +/- 0.02) L x min(-1) x kg(-1), respectively. For chlorogenic acid, the pharmacokinetic parameter t1/2beta , AUC0-t, and CL were (49.38 +/- 8.85) min, (9.54 +/- 0.95) mg x min x L(-1) and (0.09 +/- 0.003) L x min(-1) x kg(-1), respectively. The LC-MS/MS analysis method established in this study was proved to be so accurate and sensitive that it can be applied to the pharmacokinetic study of caffeic acid and chlorogenic acid.

  11. Method validation study on determination of melamine and cyanuric acid in food : CEN Collaborative Study 2014 : Melamine and cyanuric acid

    NARCIS (Netherlands)

    Elbers, I.J.W.; Traag, W.A.

    2014-01-01

    At the request of the European Committee for Standardization (CEN) by RIKILT a standard for the determination of melamine (MEL) and cyanuric acid (CYA) in food was described. In order to validate this new CEN method a ring trial was organized between February 2014 and July 2014. The objective is to

  12. Electrocatalytic and simultaneous determination of isoproterenol, uric acid and folic acid at molybdenum (VI) complex-carbon nanotube paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Beitollahi, Hadi, E-mail: h.beitollahi@yahoo.com [Environment Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Sheikhshoaie, Iran [Department of Chemistry, Faculty of Science, Shahid Bahonar University of Kerman, Kerman 76175-133 (Iran, Islamic Republic of)

    2011-11-30

    Highlights: > A molybdenum (VI) complex-carbon nanotube paste electrode have been fabricated. > This electrode reduced the oxidation potential of isoproterenol by about 175 mV. > It resolved the voltammetric waves of isoproterenol, uric acid and folic acid. - Abstract: This paper describes the development, electrochemical characterization and utilization of a novel modified molybdenum (VI) complex-carbon nanotube paste electrode for the electrocatalytic determination of isoproterenol (IP). The electrochemical profile of the proposed modified electrode was analyzed by cyclic voltammetry (CV) that showed a shift of the oxidation peak potential of IP at 175 mV to less positive value, compared with an unmodified carbon paste electrode. Differential pulse voltammetry (DPV) in 0.1 M phosphate buffer solution (PBS) at pH 7.0 was performed to determine IP in the range from 0.7 to 600.0 {mu}M, with a detection limit of 35.0 nM. Then the modified electrode was used to determine IP in an excess of uric acid (UA) and folic acid (FA) by DPV. Finally, this method was used for the determination of IP in some real samples.

  13. Ascorbic Acid Determination in Natural Orange Juice: As a Teaching Tool of Coulometry and Polarography.

    Science.gov (United States)

    Bertotti, Mauro; And Others

    1995-01-01

    Describes an experiment designed to determine ascorbic acid concentrations in natural orange juice. The experiment is used with undergraduate pharmacy students to allow understanding of the principles of operation of the coulometer and polarograph. (DDR)

  14. Determination of solvation and binding site profile within electropolymerised poly(pyrrole-N-propionic acid)

    DEFF Research Database (Denmark)

    Glidle, A.; Swann, M.J.; Gadegaard, Nikolaj

    2000-01-01

    Specular neutron reflectivity measurements were performed on electropolymerised films of poly(pyrrole-N-propionic acid) to determine the degree to which the solvents are capable of supporting biological macromolecules can penetrate the polymer film. The permeation profile of Ni2+ ions which chela...... to the polymer's carboxylic acid moieties for subsequent modified protein binding was also determined. (C) 2000 Elsevier Science B.V. All rights reserved....

  15. Rapid simultaneous determination of organic acids, free amino acids, and lactose in cheese by capillary electrophoresis.

    Science.gov (United States)

    Izco, J M; Tormo, M; Jiménez-Flores, R

    2002-09-01

    A capillary electrophoresis (CE) method for the simultaneous separation of 11 metabolically important organic acids (oxalic, formic, citric, succinic, orotic, uric, acetic, pyruvic, propionic, lactic, and butyric), 10 amino acids (Asp, Glu, Tyr, Gly, Ala, Ser, Leu, Phe, Lys, and Trp), and lactose has been optimized, validated, and tested in dairy products. Repeatability and linearity were calculated for each compound, with detection limit values as low as 0.2 x 10(-2) mM for citric acid and Gly. The method was applied to analyze yogurt and different varieties of commercial cheeses. This method yielded specific CE patterns for different varieties of cheese. Also, it has been shown to be sensitive enough to measure small changes in composition of some of those compounds in fresh cheese stored under accelerated ripening conditions for 2 d at 32 degrees C (e.g., from 1728.3 +/- 45.0 to 1166.7 +/- 4.5 mg/100 g of DM in the case of lactose, or from 23.5 +/- 0.6 to 76.8 +/- 16.7 mg/100 g of DM in the case of acetic acid).

  16. Determination of extracellular kynurenic acid in the striatum of unanesthetized rats: effect of aminooxyacetic acid

    DEFF Research Database (Denmark)

    Speciale, C; Wu, H Q; Gramsbergen, J B;

    1990-01-01

    Kynurenic acid (KYNA) production from its bioprecursor L-kynurenine (KYN) was assessed in vivo by intrastriatal microdialysis in freely moving rats. In the absence of KYN, the extracellular concentration of KYNA was below the limit of assay sensitivity (i.e. less than 8 pmol/30 microliters). In t...

  17. Determining important regulatory relations of amino acids from dynamic network analysis of plasma amino acids.

    Science.gov (United States)

    Shikata, Nahoko; Maki, Yukihiro; Nakatsui, Masahiko; Mori, Masato; Noguchi, Yasushi; Yoshida, Shintaro; Takahashi, Michio; Kondo, Nobuo; Okamoto, Masahiro

    2010-01-01

    The changes in the concentrations of plasma amino acids do not always follow the flow-based metabolic pathway network. We have previously shown that there is a control-based network structure among plasma amino acids besides the metabolic pathway map. Based on this network structure, in this study, we performed dynamic analysis using time-course data of the plasma samples of rats fed single essential amino acid deficient diet. Using S-system model (conceptual mathematical model represented by power-law formalism), we inferred the dynamic network structure which reproduces the actual time-courses within the error allowance of 13.17%. By performing sensitivity analysis, three of the most dominant relations in this network were selected; the control paths from leucine to valine, from methionine to threonine, and from leucine to isoleucine. This result is in good agreement with the biological knowledge regarding branched-chain amino acids, and suggests the biological importance of the effect from methionine to threonine.

  18. Site specific incorporation of heavy atom-containing unnatural amino acids into proteins for structure determination

    Science.gov (United States)

    Xie, Jianming; Wang, Lei; Wu, Ning; Schultz, Peter G.

    2008-07-15

    Translation systems and other compositions including orthogonal aminoacyl tRNA-synthetases that preferentially charge an orthogonal tRNA with an iodinated or brominated amino acid are provided. Nucleic acids encoding such synthetases are also described, as are methods and kits for producing proteins including heavy atom-containing amino acids, e.g., brominated or iodinated amino acids. Methods of determining the structure of a protein, e.g., a protein into which a heavy atom has been site-specifically incorporated through use of an orthogonal tRNA/aminoacyl tRNA-synthetase pair, are also described.

  19. Determination of urinary vanillylmandelic acid by direct injection and coupled-column chromatography with electrochemical detection.

    Science.gov (United States)

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

    1990-04-27

    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.

  20. A method for determining identity and relative purity of carmine, carminic acid and aminocarminic acid.

    Science.gov (United States)

    Dapson, Rw

    2005-01-01

    Carmine is one of the few dyes currently certified by the Biological Stain Commission that is not assayed for dye content. Existing assay methods are complex and do not differentiate the three cochineal derivatives carmine, carminic acid and aminocarminic acid. The latter dye is relatively new to the food trade as an acid-stable red colorant and may eventually enter the biological stains market. The assay proposed here is a two-step procedure using quantitative spectrophotometric analysis at high pH (12.5-12.6) followed by a qualitative scan of a low pH (1.90-2.10) solution. Carmine is distinct at high pH, and the remaining dyes are easily distinguished at low pH. Four instances of mislabeling are documented from 18 commercial products, but the mislabeled dyes were not certified dyes. Samples from nearly all lots of carmine certified by the Biological Stain Commission from 1920 to 2004 proved to be carmine, but they varied widely in dye content. Batches from 1920 through the 1940s were significantly richer in dye content. Variability has been extreme since 2000, and most of the poorest lots have been submitted since 1990.

  1. Determination of fatty acid composition of γ-irradiated hazelnuts, walnuts, almonds, and pistachios

    Science.gov (United States)

    Gecgel, Umit; Gumus, Tuncay; Tasan, Murat; Daglioglu, Orhan; Arici, Muhammet

    2011-04-01

    Hazelnut, walnut, almonds, and pistachio nuts were treated with 1, 3, 5, and 7 kGy of gamma irradiation, respectively. Oil content, free fatty acid, peroxide value, and fatty acid composition of the nuts were investigated immediately after irradiation. The data obtained from the experiments indicated that gamma irradiation did not cause any significant change in the oil content of nuts. In contrast, free fatty acid and peroxide value of the nuts increased proportionally to the dose (p<0.05). Among the fatty acids determined, the concentration of total saturated fatty acids increased while total monounsaturated and total polyunsaturated fatty acids decreased with the irradiation dose (p<0.05 and <0.01).

  2. Determination of fatty acid composition of {gamma}-irradiated hazelnuts, walnuts, almonds, and pistachios

    Energy Technology Data Exchange (ETDEWEB)

    Gecgel, Umit, E-mail: ugecgel@nku.edu.t [Namik Kemal University, Agricultural Faculty, Department of Food Engineering, 59030 Tekirdag (Turkey); Gumus, Tuncay; Tasan, Murat; Daglioglu, Orhan; Arici, Muhammet [Namik Kemal University, Agricultural Faculty, Department of Food Engineering, 59030 Tekirdag (Turkey)

    2011-04-15

    Hazelnut, walnut, almonds, and pistachio nuts were treated with 1, 3, 5, and 7 kGy of gamma irradiation, respectively. Oil content, free fatty acid, peroxide value, and fatty acid composition of the nuts were investigated immediately after irradiation. The data obtained from the experiments indicated that gamma irradiation did not cause any significant change in the oil content of nuts. In contrast, free fatty acid and peroxide value of the nuts increased proportionally to the dose (p<0.05). Among the fatty acids determined, the concentration of total saturated fatty acids increased while total monounsaturated and total polyunsaturated fatty acids decreased with the irradiation dose (p<0.05 and <0.01).

  3. Chromatographic determination of amino acid enantiomers in beers and raw materials used for their manufacture.

    Science.gov (United States)

    Erbe, T; Brückner, H

    2000-06-09

    Using gas chromatography (GC) on a chiral stationary phase, accompanied by high-performance liquid chromatography, beers and raw materials used for manufacturing (hops, barley grains, malts) were investigated for the pattern and quantities of amino acid enantiomers. Although L-amino acids were most abundant, certain D-amino acids were detected in all beers and most of the raw materials. Highest amounts of D-amino acids were detected in special beers such as Berliner Weisse that underwent bottle-conditioning with lactic cultures, and Belgian fruit beers produced by spontaneous fermentation. It is demonstrated that GC on chiral stationary phases is highly suitable for the quantitative determination of amino acid enantiomers in beers and raw materials used for their manufacture. Quantities, relative amounts and pattern of amino acid enantiomers can serve in particular as chiral markers for the authenticity of special beers.

  4. Simultaneous determination of acetylsalicylic and salicylic acids by first derivative spectrometry in pharmaceutical preparations

    Science.gov (United States)

    Rogić, Dunja

    1993-03-01

    A multicomponent first derivative UV spectrometric procedure for determination of acetylsalicylic acid (aspirin) and salicylic acid in the solution containing 1 % (w/v) of citric acid in some pharmaceutical preparations is presented. The method is based on the use of the first derivative minimum spectrometric measurements at 286 nm for aspirin and at 318 nm for salicylic acid. Four kinds of cmmercial Aspirin tablets were assayed without a long pretreatment of the pharmaceuticals from the tablet additives. Beer's law is obeyed from 13.62-68.1 μg ml -1 of aspirin and from 2.723-13.616 μg ml -1 of salicylic acid. Detection limits at the 0.05 level of significance were calculated to be 1.24 and 0.25 μg ml -1 with relative standard deviations of 1.09 % and 1.2 % of aspirin and salicylic acid, respectively.

  5. Potentiometric Determination of Phytic Acid and Investigations of Phytate Interactions with Some Metal Ions.

    Science.gov (United States)

    Marolt, Gregor; Pihlar, Boris

    2015-01-01

    Determination of correct amount (concentration) of phytic acid is of vital importance when dealing with protonation and/or metal complexation equilibria. A novel approach for precise and reliable assay of phytic acid, based on the difference between end points by potentiometric titration, has been presented. Twelve phytic acid protons are classified into three groups of acidity, which enables detection of 2 to 3 distinct equivalent points (EPs) depending on experimental conditions, e.g. counter-ion concentration. Using the differences between individual EPs enables correct phytate determination as well as identification of potential contamination and/or determination of initial protonation degree. Impact of uncertainty of phytate amount on the calculation of protonation constants has been evaluated using computer simulation program (Hyperquad2013). With the analysis of titration curves different binding sites on phytate ligand have been proposed for complexation of Ca2+ and Fe3+ ions.

  6. The comparison of techniques and methods for L-ascorbic acid determination in the fruits

    Directory of Open Access Journals (Sweden)

    Cvetković Biljana R.

    2012-01-01

    Full Text Available Vitamin C is an essential vitamin for human nutrition; with the L-ascorbic acid (AA being the active form of vitamin C. Hence, determination of the L-ascorbic acid in the natural and processed foods is very important. In the past, plenty of methods based on the reversible redox reaction of AA oxidation/DHA reduction were developed. Because of L-ascorbic acid instability in aqueous solutions, it is useful to analyze various types of extraction. The aim of this study is to compare three different methods and three different extractants for the L-ascorbic acid determination. Fruits (kiwi, lemon, orange, and grapefruit were purchased from a local market. The L-ascorbic acid in these four samples was determined by the three different methods: the AOAC, the HPLC method with three different types of extractions, and the colorimetric method using ascorbate-oxidase. For the HPLC measurements, one part of the fruits was extracted with distilled water, the second with potassium hydrogen phosphate, and the third with 3% meta-phosphoric acid (MPA in 8% acetic acid. The HPLC measurements of each sample were repeated three times, the AOAC titration was repeated five times, and in the calorimetric method three measurements were performed. The results were statistically evaluated related to sample basis. Statistical analysis shows that there is a significant difference between the results for all three methods of extraction for all samples, except for the grapefruit sample where no significant difference was observed between the results obtained after the buffer extraction (E2 and the metaphosphoric acid in acetic acid extraction (E3. Discriminative analysis for the HPLC determinations proves that there is a clear difference and defined border between the samples in relation to the methods of extraction during the HPLC determination.

  7. A method for the determination of the dissociation constants of acids with an uncalibrated glass electrode

    NARCIS (Netherlands)

    Bos, M.; Lengton, W.

    1975-01-01

    A method is presented for the determination of absolute pKa values of acids in solvents with a high dielectric constant by potentiometry with an uncalibrated glass electrode; in the determination, the glass electrode becomes calibrated. The method has the advantage that it is rapid and simple. Moreo

  8. Validation of a multi-analyte HPLC-DAD method for determination of uric acid, creatinine, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid and 2-methylhippuric acid in human urine.

    Science.gov (United States)

    Remane, Daniela; Grunwald, Soeren; Hoeke, Henrike; Mueller, Andrea; Roeder, Stefan; von Bergen, Martin; Wissenbach, Dirk K

    2015-08-15

    During the last decades exposure sciences and epidemiological studies attracts more attention to unravel the mechanisms for the development of chronic diseases. According to this an existing HPLC-DAD method for determination of creatinine in urine samples was expended for seven analytes and validated. Creatinine, uric acid, homovanillic acid, niacinamide, hippuric acid, indole-3-acetic acid, and 2-methylhippuric acid were separated by gradient elution (formate buffer/methanol) using an Eclipse Plus C18 Rapid Resolution column (4.6mm×100mm). No interfering signals were detected in mobile phase. After injection of blank urine samples signals for the endogenous compounds but no interferences were detected. All analytes were linear in the selected calibration range and a non weighted calibration model was chosen. Bias, intra-day and inter-day precision for all analytes were below 20% for quality control (QC) low and below 10% for QC medium and high. The limits of quantification in mobile phase were in line with reported reference values but had to be adjusted in urine for homovanillic acid (45mg/L), niacinamide 58.5(mg/L), and indole-3-acetic acid (63mg/L). Comparison of creatinine data obtained by the existing method with those of the developed method showing differences from -120mg/L to +110mg/L with a mean of differences of 29.0mg/L for 50 authentic urine samples. Analyzing 50 authentic urine samples, uric acid, creatinine, hippuric acid, and 2-methylhippuric acid were detected in (nearly) all samples. However, homovanillic acid was detected in 40%, niacinamide in 4% and indole-3-acetic acid was never detected within the selected samples.

  9. Determination of the uronic acid composition of seaweed dietary fibre by HPLC.

    Science.gov (United States)

    Sánchez-Machado, D I; López-Cervantes, J; López-Hernández, J; Paseiro-Losada, P; Simal-Lozano, J

    2004-03-01

    A high-performance liquid chromatographic (HPLC) method is described for determination of the ratio of beta-d-mannuronic acid to alpha-l-guluronic acid (M/G ratio) in dietary fibre of edible seaweeds. Total dietary fibre (TDF) content was determined gravimetrically. The TDF fraction was hydrolysed with 12 m and 1 m H(2)SO(4), then neutralized with AG 4 x 4 resin. The uronic acids were separated in a Tracer Extrasil SAX 5 micro m column (25 cm x 4 mm) at 35 degrees C, with 2 mm KH(2)PO(4) containing 5% methanol as mobile phase at a fl ow rate of 1.5 mL/min. The detection wavelength was UV 210 nm. The chromatographic identifications of beta-d-mannuronic acid and alpha-l-guluronic acid were confirmed by liquid chromatography-mass spectrometry (LC-MS). The method precision was 1.4% for beta-d-mannuronic acid and 3.5% for alpha-l-guluronic acid. The method was used to determine M/G ratio in canned seaweeds (Saccorhiza polyschides and Himanthalia elongata) and in dried seaweeds (H. elongata, Laminaria ochroleuca, Undaria pinnatifida, Palmaria sp. and Porphyra sp.).

  10. Determination of vanillylmandelic, 5-hydroxyindoleacetic and homovanillic acid in urine by isocratic liquid chromatography.

    Science.gov (United States)

    Bonfigli, A R; Coppa, G; Testa, R; Testa, I; De Sio, G

    1997-01-01

    A new isocratic HPLC method, employing electrochemical detection, is described for the determination of urinary vanillylmandelic acid, 5-hydroxyindoleacetic acid and homovanillic acid. The main advantages of this technique are: simplicity, simultaneous determination of all analytes, the absence of an extraction procedure, isocratic elution and low cost. The diluted urine is injected onto a C18 reversed phase column. The mobile phase is potassium dihydrogenphosphate buffer containing 1-heptanesulphonic acid, methanol and acetonitrile. The calibration curves are linear from 0.1 to 50 mg/l; the precision data show CV less than 2.36% for within-day assay and less than 2.72% for day-to-day assays. The mean recoveries for supplemented samples are 98.2 to 102.0% for vanillylmandelic acid, 99.6 to 103.9% for 5-hydroxyindoleacetic acid and 98.7 to 102.0% for homovanillic acid. In comparisons of the present method with Radjaipur's extraction method (Radjaipur M. et al., Eur J Clin Chem Clin Biochem 1994; 32:609-13) the slopes for the three analytes were nearly 1, and the confidence region of the intercepts was close to 0. In conclusion the technique seems to be suitable for routine determination of the three analytes, especially for mass screening purposes.

  11. Simple and Rapid Method for the Determination of Uric Acid-Independent Antioxidant Capacity

    Directory of Open Access Journals (Sweden)

    Darko Modun

    2011-08-01

    Full Text Available Determination of the relative contribution of uric acid level increases to the total measured antioxidative activity could be very useful for testing antioxidative products and their effect on human health. The aim of this report is to present a simple spectrophotometric method that combines the measurement of total antioxidative capacity of a sample by ferric reducing/antioxidative power (FRAP assay, with the uricase-reaction (specific elimination of uric acid, in order to establish and correct for the contribution of uric acid in FRAP values. We measured FRAP values, with (uric acid-independent antioxidant capacity, TAC-UA and without (total antioxidant capacity, TAC uricase treatment, and expressed it as μmol/L of uric acid equivalents. In such way, it was possible to determine both total and uric acid-independent antioxidant capacity, plasma uric acid (UA, as the difference between TAC and TAC-UA, and the ratio of the uric acid in total antioxidant capacity (UA/TAC.

  12. Simultaneous determination of 2-naphthoxyacetic acid and indole-3-acetic acid by first derivation synchronous fluorescence spectroscopy.

    Science.gov (United States)

    Liu, Xiangxiang; Wan, Yiqun

    2013-07-01

    A simple, rapid, sensitive and selective method for simultaneously determining 2-naphthoxyacetic acid (BNOA) and Indole-3-Acetic Acid (IAA) in mixtures has been developed using derivation synchronous fluorescence spectroscopy based on their synchronous fluorescence. The synchronous fluorescence spectra were obtained with Δλ=100 nm in a pH 8.5 NaH2PO4-NaOH buffer solution, and the detected wavelengths of quantitative analysis were set at 239 nm for BNOA and 293 nm for IAA respectively. The over lapped fluorescence spectra were well separated by the synchronous derivative method. Under optimized conditions, the limits of detection (LOD) were 0.003 μg/mL for BNOA and 0.012 μg/mL for IAA. This method is simple and expeditious, and it has been successfully applied to the determination of 2-naphthoxyacetic acid and indole-3-acetic acid in fruit juice samples with satisfactory results. The samples were only filtrated through a 0.45 μm membrane filter, which was free from the tedious separation procedures. The obtaining recoveries were in the range of 83.88-87.43% for BNOA and 80.76-86.68% for IAA, and the relative standard deviations were all less than 5.0%. Statistical comparison of the results with high performance liquid chromatography Mass Spectrometry (HPLC-MS) method revealed good agreement and proved that there were no significant difference in the accuracy and precision between these two methods.

  13. Simultaneous determination of 2-naphthoxyacetic acid and indole-3-acetic acid by first derivation synchronous fluorescence spectroscopy

    Science.gov (United States)

    Liu, Xiangxiang; Wan, Yiqun

    2013-07-01

    A simple, rapid, sensitive and selective method for simultaneously determining 2-naphthoxyacetic acid (BNOA) and Indole-3-Acetic Acid (IAA) in mixtures has been developed using derivation synchronous fluorescence spectroscopy based on their synchronous fluorescence. The synchronous fluorescence spectra were obtained with Δλ = 100 nm in a pH 8.5 NaH2PO4-NaOH buffer solution, and the detected wavelengths of quantitative analysis were set at 239 nm for BNOA and 293 nm for IAA respectively. The over lapped fluorescence spectra were well separated by the synchronous derivative method. Under optimized conditions, the limits of detection (LOD) were 0.003 μg/mL for BNOA and 0.012 μg/mL for IAA. This method is simple and expeditious, and it has been successfully applied to the determination of 2-naphthoxyacetic acid and indole-3-acetic acid in fruit juice samples with satisfactory results. The samples were only filtrated through a 0.45 μm membrane filter, which was free from the tedious separation procedures. The obtaining recoveries were in the range of 83.88-87.43% for BNOA and 80.76-86.68% for IAA, and the relative standard deviations were all less than 5.0%. Statistical comparison of the results with high performance liquid chromatography Mass Spectrometry (HPLC-MS) method revealed good agreement and proved that there were no significant difference in the accuracy and precision between these two methods.

  14. QUANTITATIVE DETERMINATION OF FATTY ACIDS IN INFANT FORMULA BY GAS CHROMATOGRAPHY WITHOUT DERIVATIZATION

    Directory of Open Access Journals (Sweden)

    M. R. Oveisi

    2006-08-01

    Full Text Available Fatty acids play important roles in biological systems and the newborns fatty acids requirements are covered only by the milk. It is of particular interest to qualify the content of the fatty acids in the milk. This study was performed to determine the levels of some fatty acids in the infant formulas and also to describe a method without derivatization for the fatty acids analysis and applying it to the control of infant formulas. Free fatty acids were produced by adding isopropanol- KOH to milk fat extract and heating it to saponify and acidify by H2SO4. Free fatty acids were extracted and were quantified by capillary gas chromatography on a fused silica column (AT-1000 and flame ionization detector. The average experimental values of lauric, palmitic, stearic and linoleic fatty acids contents of twenty infant formulas were 6.47, 16.52, 2.11 and 14.56 g/100g, respectively. The obtained experimental values of lauric and linoleic fatty acids contents of twenty infant formulas were in good agreement with the values proposed by standards of codex alimentary.

  15. Eletropolymerization of Niacinamide for Fabrication of Electrochemical Sensor: Simultaneous Determination of Dopamine, Uric Acid and Ascorbic Acid

    Institute of Scientific and Technical Information of China (English)

    ZHU Xiaohong; LIN Xiangqin

    2009-01-01

    Two polymeric thin film modified electrodes, poly-niacinamide/glassy carbon electrode (poly-NA/GCE) and poly-nicotinic acid/glassy carbon electrode (poly-NC/GCE), have be fabricated at glassy carbon electrodes by sim-ple electropolymerization of niacinamide (NA) in different potential scan ranges of cyclic voltammetry (CV). These two electrodes all showed catalytic ability towards the oxidation of dopamine (DA), uric acid (UA) and ascorbie acid (AA) by obvious reductions of overpotentials, giving well-resolved voltammetric peaks, which allow simulta-neously determination of DA, UA and AA. The poly-NC/GCE showed even higher electrocatalytic activity than the poly-NA/GCE. The electrochemical behavior of poly-NC/GCE was investigated by CV and differential pulse voltammetry (DPV) for determination of DA, UA and AA. The linear ranges of the concentration for the determination of AA, DA and UA using DPV were 75-3000, 0.37-16 and 0.741--230 μmol·L-1, respectively. The slopes of the linear calibration curves for the detection were estimated to be 5.6, 1140 and 102 mA·L·mol-1 for AA, DA and UA, respectively. The poly-NC/GCE shows excellent sensitivity, good selectivity and antifouling properties.

  16. Trace determination of cobalt ion by using malic acid-malonic acid double substrate oscillating chemical system

    Institute of Scientific and Technical Information of China (English)

    Jie Wang; Wu Yang; Jie Ren; Miao Guo; Xiao Dong Chen; Wen Bin Wang; Jin Zhang Gao

    2008-01-01

    A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii (B-Z) oscillating chemical system to form a double substrate one. The results showed that when the concentration of cobalt ion was in the range of 5.27× 10-8 to 5.37×10-12mol L-1 the change of the oscillating period was directly proportional to the negative logarithm of cobalt ion concentration. The sensitivity and precision of the developed method were quite satisfactory. The limit of detection was down to 5.20 x 10-13 mol L-1 which was a highest sensitivity found for determination of metal ions using oscillating chemical reaction so far. Some factors influencing the determination were also examined. The method has been successfully used to determine cobalt ion in vitamin B12 injection.

  17. Fast determination of bioactive phytic acid and pyrophosphate in walnuts using microwave accelerated extraction.

    Science.gov (United States)

    Liu, Tong; He, Liu; Valiente, Manuel; López-Mesas, Montserrat

    2017-04-15

    Bioactive compounds phytic acid (IP6) and pyrophosphate (PPi) are minor components of walnuts with the ability of being inhibitors of urolithiasis, among others. Since simultaneous analysis of IP6 and PPi have known drawbacks, a new method to determine their content in walnuts has been developed with emphasis on their extraction from walnuts by microwave-assisted extraction (MAE). Acid content of extracting solvent, extraction time and temperature were optimized. After extraction, compounds were purified by selective adsorption/desorption on an anion exchange solid phase extraction and analyzed by inductive coupled plasma/mass spectrometry. A mixture of H2SO4 and HCl as solvent to extract both, IP6 and PPi, provided results slightly higher than those determined by conventional extraction with no statistical difference. The possible hydrolysis of phytic acid by MAE was analyzed. Compared with the conventional acid extraction method, significant improvement is achieved by the MAE method reducing extraction time from 3h to 10min.

  18. Chemiluminescence Determination of Benzoic Acid Using A Solid-Phase Verdigris Reactor

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new chemiluminescence flow system has been developed for sequential determina-tion of benzoic acid based on the reaction of the compound with copper carbonate entrapped in a solid-phase reactor. It was found that the unsaturated complex of Cu(II) and benzoic acid (1:1) has strong catalytic effect on the luminol-H2O2 chemiluminescence reaction. The calibration graph is linear over the range of 0.025 ~ 60 μg/mL of benzoic acid, with a relative standard deviation of less than 3.0 %, and the detection limit is 0.01μg@mL-1. The proposed method was applied to the determination of benzoic acid content in different pharmaceutical formulations.

  19. Determination of the Fatty Acid content of pumpkin seed, pygeum, and saw palmetto.

    Science.gov (United States)

    Ganzera, M; Croom, E M; Khan, I A

    1999-01-01

    Fatty acids are major components of many plants, foods and medicines, including pumpkin seeds (Cucubita pepo), pygeum bark (Prunus africana) and saw palmetto (Serenoa repens). With the gas chromatography methods reported here, free fatty acids of these species can be quantified as their trimethylsilyl derivatives. Because of their different fatty acid contents and composition, the gas chromatography method can distinguish which of three plant species was extracted, and, in the case of S. repens, the method of extraction. Although phytosterols can be separated by this method, their content is too low to be assigned directly. The total fatty acid content can be determined through formation of the methyl esters. This is helpful for estimation of the kind and percentage of fatty acids that are present as triglyceride esters in the plant material and for standardization of the products.

  20. Quantitative determination of citric acid in seminal plasma by using Raman spectroscopy.

    Science.gov (United States)

    Huang, Zufang; Chen, Xiwen; Li, Yongzeng; Chen, Jinhua; Lin, Juqiang; Wang, Jing; Lei, Jinping; Chen, Rong

    2013-07-01

    In this study, Raman spectroscopy was first used to study the linear relationship between Raman spectral intensities and citric acid concentrations in aqueous solution. By using the specific Raman band of 942 cm(-1), concentrations of citric acid ranging from 2 to 20 mg/mL were observed linearly (R(2) = 0.993), and the limit of detection was 1.0 mg/mL. Then, citric acid detection in clinical seminal plasma ultrafiltrate samples was performed, and the intensity of the Raman-specific peak demonstrates a good linear correlation (R(2) = 0.946) with citric acid concentrations determined by the enzymatic method. Our results showed that Raman spectroscopy has the potential of being applied to detect concentrations of citric acid in seminal plasma in clinic.

  1. Determination of ascorbic acid and carotenoids in food commodities by liquid chromatography with mass spectrometry detection.

    Science.gov (United States)

    Frenich, A Garrido; Torres, M E Hernández; Vega, A Belmonte; Vidal, J L Martínez; Bolaños, P Plaza

    2005-09-21

    Two methods, one to determine ascorbic acid and one to determine lycopene and beta-carotene, in vegetables and fruits by liquid chromatography coupled with mass spectrometry (LC-MS) have been established. The chromatographic separation of the studied compounds and their MS parameters were optimized to improve selectivity and sensitivity. In both methods, separation was carried out with two coupled columns, first a C(18) and then a dC(18), using as mobile phase 70% methanol (0.005% acetic acid) and 30% acetic acid 0.05% for ascorbic acid determination and a mixture of methanol, tetrahydrofuran, and acetonitrile (60:30:10 v/v/v) for carotenoid analysis in isocratic mode. The molecular ion was selected for the quantification in selective ion monitoring (SIM) mode. Ascorbic acid was detected with electrospray ionization probe (ESI) in negative mode, while chemical ionization atmospheric pressure (APCI) in positive mode was used for the target carotenoids. The methodology for ascorbic acid analysis is based on an extraction with polytron using methanol and a mixture of methaphosphoric acid and acetic acid. Extraction of the carotenoids was carried out with tetrahydrofuran/methanol (1:1) (v/v). The proposed methods were applied, after their corresponding validations, to the analysis of four varieties of tomatoes, tomato in tin enriched and dried tomato, and to the analysis of mango and kiwi fruits, to compare the content in these compounds. Moreover, the influence of the process of freezing and the effect that the manipulation/preservation has in the content of ascorbic acid in tomato have also been studied.

  2. Simple and Rapid Method for the Determination of Uric Acid-Independent Antioxidant Capacity

    OpenAIRE

    2011-01-01

    Determination of the relative contribution of uric acid level increases to the total measured antioxidative activity could be very useful for testing antioxidative products and their effect on human health. The aim of this report is to present a simple spectrophotometric method that combines the measurement of total antioxidative capacity of a sample by ferric reducing/antioxidative power (FRAP) assay, with the uricase-reaction (specific elimination of uric acid), in order to establish and co...

  3. [Determination of amino acids in honey by capillary electrophoresis with indirect ultraviolet detection].

    Science.gov (United States)

    Zhou, Xianjing; Shi, Yanping

    2013-07-01

    A method of capillary electrophoresis with indirect ultraviolet (UV) detection was developed for the separation and determination of nine amino acids such as lysine, tryptophan, glutamic acid, etc. The effects of sodium dihydrogen phosphates concentration, pH of buffer and sample injection type and time on the reproducibility and efficiency were investigated. The optimum injection time was 5 s at 5 kPa. The optimum electrophoretic conditions were as follow: 10 mmol/L sodium dihydrogen phosphates (pH 10. 2) containing 0. 5 mmol/L cetrimonium bromide, 20 mmol/L nicotinic acid and 10% (v/v) methanol as running buffer, applied voltage of - 15 kV, detection wavelength of 220 nm. The base line separation of the nine amino acids was achieved successfully within 11 min. The lowest detection limit was 0. 3 mg/L. All of the nine analytes showed good linearities within 1. 0 - 1000 mg/L. The relative standard deviations of migration time and peak area were 0. 64% - 5. 83%. The recoveries of the eight amino acids spiked in a real sample were between 60. 00% and 118.37%. The method was applied in the determination of the amino acids in honey samples from different nectar plants and origins. Prolin, serine and aspartic acid were found in five honey samples, and tryptophan was only found in a litchi honey sample. This method can provide good reference to the evaluation of the quality and nectar origin of honey.

  4. Simple determination of L-ascorbic acid on TLC by visual detection using autocatalytic reaction.

    Science.gov (United States)

    Akasaka, Kazuaki

    2013-01-01

    The L-ascorbic acid concentration in beverages was measured after separation by silica gel thin layer chromatography (TLC) by visually determining the time in autocatalytic reaction for the L-ascorbic acid spot to turn the same yellow color of the background and disappear (the end time of the induction period) after spraying the slide with a 3,6-dihydroxyxanthane solution. There was a good linear relationship between the end time of the induction period and the concentration of L-ascorbic acid for concentrations in the range of 5.0 - 20 mM (r(2) = 0.9944). In addition, there was a good relationship expressed by a quadratic equation in the concentration range of 0.1 - 5.0 mM (r(2) = 0.9975). The relative standard deviations of the L-ascorbic acid values for 3 beverages (2.2 - 8.6 mM) were less than 5% (n = 5), and the recovery of 5.0 mM L-ascorbic acid from 4 beverages (0.7 - 7 mM) was 97 - 110%. A good correlation was also observed between the L-ascorbic acid values of 23 beverages (0 - 86 mM) determined by the proposed TLC method and the colorimetric method contained in a commercially available kit for L-ascorbic acid (r(2) = 0.9945).

  5. Determination of water-soluble forms of oxalic and formic acids in soils by ion chromatography

    Science.gov (United States)

    Karicheva, E.; Guseva, N.; Kambalina, M.

    2016-03-01

    Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils. The aim of the article is to determine water-soluble forms of same carboxylic acids — (oxalic and formic acids) in soils by ion chromatography with gradient elution. For the separation and determination of water-soluble carboxylic acids we used reagent-free gradient elution ion-exchange chromatography ICS-2000 (Dionex, USA), the model solutions of oxalate and formate ions, and leachates from soils of the Kola Peninsula. The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography. A stability indicating method was developed for the simultaneous determination of water-soluble organic acids in soils. The method has shown high detection limits such as 0.03 mg/L for oxalate ion and 0.02 mg/L for formate ion. High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L (formate), from 0.1 mg/g to 25 mg/L (oxalate). The concentration of formate and oxalate ions in soil samples is from 0.04 to 0.9 mg/L and 0.45 to 17 mg/L respectively.

  6. Application of flow-injection potentiometric system for determination of total concentration of aliphatic carboxylic acids.

    Science.gov (United States)

    Mroczkiewicz, Monika; Górski, Łukasz; Zamojska-Jaroszewicz, Anna; Szewczyk, Krzysztof W; Malinowska, Elżbieta

    2011-09-30

    In this work, flow-injection system with potentiometric detection was tested for determination of total carboxylic acid concentration. Detection part of the examined system consists of ion-selective electrodes (ISEs) with polymer membranes of different compositions. First electrode is based on Zr(IV)-tetraphenylporphyrin as ionophore selective towards carboxylic acid anions, the membrane of second one contains only liphophilic anion exchanger - tridodecylmethylammonium chloride. Final response of the system is a result of combination of EMF signals from both electrodes. Combination of two detectors enables significant decrease of differences between potentiometric signals induced by mixtures of studied anions of various concentrations as compared to results obtained only with metalloporphyrin-based ISE. The use of anion-exchanger based detector allows for elimination of the influence of aliphatic carboxylic acids lipophilicity. Proposed potentiometric flow-injection system was employed for determination of short-chain aliphatic carboxylic acids (so-called VFA - volatile fatty acids) in samples originating from an anaerobic digester. Results obtained for these relatively complicated samples are in good agreement with results obtained with the use of reference colorimetric method. Linear response towards carboxylic acids was observed in the concentration range of 10(-4) to 10(-2)mold m(-3), with the slopes in the range of -110 to -150 mV dec(-1) (for acetate(-) and butyrate(-), respectively). System enables for determination of about 6 samples per hour. Life time of ISEs average about 2 months.

  7. Simultaneous determination of rutin and ascorbic acid mixture in their pure forms and combined dosage form

    Science.gov (United States)

    Attia, Tamer Z.

    2016-12-01

    A simple, rapid, sensitive and selective high performance liquid chromatographic (HPLC) method with ultraviolet detection has been developed for simultaneous determination of ascorbic acid and rutin in pure forms and pharmaceutical dosage form. HPLC separation was performed on Phenomenex C18 analytical column with 0.1% v/v acetic acid in water and acetonitrile (75:25, v/v), as mobile phase. The separation was done at ambient temperature with flow rate of 1 mL·min- 1 in isocratic mode. HPLC measurements were carried out using ultraviolet detection wavelength at 257 nm. The average retention times were 2.72 and 7.00 min for ascorbic acid and rutin, respectively. The calibration plots were constructed over the concentration range of 5.0-30.0 for ascorbic acid and 10.0-60.0 μg·mL- 1 for rutin. The limits of detection were 1.06 and 1.89 μg·mL- 1 and limits of quantification were 3.54 and 6.31 μg·mL- 1 for ascorbic acid and rutin, respectively. The proposed HPLC-UV method was successfully applied for determination of ascorbic acid in its tablets and for simultaneous determination of the studied drugs in their laboratory prepared mixtures and in pharmaceutical formulation. Statistical comparisons of the results with the reference method show an excellent agreement and indicate no significant difference in respect to accuracy and precision.

  8. Flow-injection Spectrophotometric Determination of Uric Acid in Urine via Prussian Blue Reaction

    Institute of Scientific and Technical Information of China (English)

    WASEEM Amir; YAQOOB Mohammad; NABI Abdul; MURTAZA Ghulam; HUSSAIN Izhar

    2011-01-01

    A simple and sensitive flow injection(FI)spectrophotometric method was reported for the determination of uric acid based on the reduction of Fe(Ⅲ)/ferricyanide in the presence of uric acid.The in situ reduced ions reacted with unreduced portion of ferricyanide/Fe(Ⅲ)to form soluble Prussian blue,which was monitored at an absorption wavelength of 735 nm.The optimized conditions allow a linear calibration graph in a concentration range of 1-100μmol/L.The relative standard deviation was in a range of 0.5%-2.5%,with a detection limit(3σ blank)of 0.3 μmol/L and a sampling frequency of 60 injection/h was obtained.The effect of common substances present in human physiological fluids on the determination of uric acid was examined.The method was applied to determining uric acid in human urine samples with the recoveries in a range of 96%-105%.The results agree well with those by spectrophotometric reference method at a confidence level of 95%.Spectrophotometric procedures for uric acid determination in clinical samples were reviewed briefly.

  9. Determination of fatty acid profile in ram spermatozoa and seminal plasma.

    Science.gov (United States)

    Díaz, R; Torres, M A; Bravo, S; Sanchez, R; Sepúlveda, N

    2016-08-01

    Fatty acids are important in male reproductive function because they are associated with membrane fluidity, acrosome reaction, sperm motility and viability, but limited information exists about the fatty acid profile of ram semen. Our aim was to determine the fatty acid composition in ram spermatozoa and seminal plasma. Sixty ejaculates were obtained from three ram (20 ejaculates/ram) using artificial vagina. Ram spermatozoa (RS) and seminal plasma (SP) were separated using centrifugation, and the fatty acids were analysed by gas chromatography. Total lipids obtained in ram spermatozoa were 1.8% and 1.6% in seminal plasma. Saturated fatty acid (SFA) was proportionally major in SP (66.6%) that RS (49.9%). The highest proportions of SFA corresponded to C4:0 (RS = 16.3% and SP = 28.8%) and C16:0 (RS = 16.3% and PS = 20%). The most important unsaturated fatty acid (UFA) was docosahexaenoic acid (DHA), 44.9% in RS and 31.5% in SP. The profile of fatty acid and their proportions showed differences between spermatozoa and seminal plasma.

  10. Determination of organic acids in biological fluids by ion chromatography: plasma lactate and pyruvate and urinary vanillylmandelic acid.

    Science.gov (United States)

    Rich, W; Johnson, E; Lois, L; Kabra, P; Stafford, B; Marton, L

    1980-09-01

    We describe the general aspects of ion chromatography and how on-line counted ion-exchange techniques can be utilized to determine pyruvic and lactic acids in plasma and vanillymandelic acid in urine. Pyruvate and lactate are extracted from deproteinized plasma by use of an ion-exclusion resin. After elution from the resin, the plasma extract is chromatographed on an anion-exchange column, with 0.66 mmol/L sodium bicarbonate as the mobile phase. The effluent is detected with an electrical conductivity cell. Vanillylmandelic acid is extracted from diluted urine by use of an anion-exchange resin. After elution from resin, the urine extract is chromatographed on an ion-exclusion column, followed by electrochemical detection. We evaluated the procedures for precision, linearity, analytical recovery, intefering substances, and correlation with an established procedure. the combination of a preliminary resin extraction, an ion chromatographic separation, and a conductivity or electrochemical detector results in rapid, specific methods that can be adapted for use in the clinical laboratory. Preliminary data for other organic acids are presented.

  11. Simultaneous determination of shikimic acid, salicylic acid and jasmonic acid in wild and transgenic Nicotiana langsdorffii plants exposed to abiotic stresses.

    Science.gov (United States)

    Scalabrin, Elisa; Radaelli, Marta; Capodaglio, Gabriele

    2016-06-01

    The presence and relative concentration of phytohormones may be regarded as a good indicator of an organism's physiological state. The integration of the rolC gene from Agrobacterium rhizogenes and of the rat glucocorticoid receptor (gr) in Nicotiana langsdorffii Weinmann plants has shown to determine various physiological and metabolic effects. The analysis of wild and transgenic N. langsdorffii plants, exposed to different abiotic stresses (high temperature, water deficit, and high chromium concentrations) was conducted, in order to investigate the metabolic effects of the inserted genes in response to the applied stresses. The development of a new analytical procedure was necessary, in order to assure the simultaneous determination of analytes and to obtain an adequately low limit of quantification. For the first time, a sensitive HPLC-HRMS quantitative method for the simultaneous determination of salicylic acid, jasmonic acid and shikimic acid was developed and validated. The method was applied to 80 plant samples, permitting the evaluation of plant stress responses and highlighting some metabolic mechanisms. Salicylic, jasmonic and shikimic acids proved to be suitable for the comprehension of plant stress responses. Chemical and heat stresses showed to induce the highest changes in plant hormonal status, differently affecting plant response. The potential of each genetic modification toward the applied stresses was marked and particularly the resistance of the gr modified plants was evidenced. This work provides new information in the study of N. langsdorffii and transgenic organisms, which could be useful for the further application of these transgenes.

  12. Determination of acetylsalicylic acid and its major metabolites in bovine urine using ultra performance liquid chromatography.

    Science.gov (United States)

    Castillo-García, M L; Aguilar-Caballos, M P; Gómez-Hens, A

    2015-03-15

    A new method based on ultra high performance liquid chromatography (UPLC) with photometric and fluorometric detection for the determination of acetylsalicylic acid and its main metabolites, namely gentisic, salicylic and salicyluric acids, in bovine urine samples is reported. Photometric detection was used for acetylsalicylic acid determination, whereas the native fluorescence of the metabolites was monitored using fluorometric detection. The separation was performed under isocratic conditions, using acetonitrile-phosphate solution (3.5mM, pH 3.5) (26:74, v/v) as the mobile phase. The retention times of the four compounds were lower than 2min, which are shorter than those achieved using conventional HPLC. Under the optimum separation conditions, the dynamic ranges and detection limits (ngmL(-1)) were: 0.2-2500, 0.09 for gentisic acid; 0.2-2500, 0.08 for salicylic acid and 2.5-15,000, 1.1 for salicyluric acid, using fluorescence detection, and 10-25,000, 2.2 for acetylsalicylic acid, using UV detection. Intra-day and inter-day precision data were assessed at two levels of concentration of each analyte using both detection systems. The selectivity of the method was checked by assaying different drugs of veterinary use showing that most of them did not interfere with the determination of the analytes. The method has been applied to the analysis of bovine urine samples, which only required a simple clean up step of the samples prior to injection in the UPLC system. A recovery study was performed, which provided values in the range of 80-100%. This fact proves the practical usefulness of this method as an ultrafast analytical tool for the therapeutic control of acetylsalicylic acid administration in bovine animals intended for food production.

  13. Determination of gallic acid with rhodanine by reverse flow injection analysis using simplex optimization.

    Science.gov (United States)

    Phakthong, Wilaiwan; Liawruangrath, Boonsom; Liawruangrath, Saisunee

    2014-12-01

    A reversed flow injection (rFI) system was designed and constructed for gallic acid determination. Gallic acid was determined based on the formation of chromogen between gallic acid and rhodanine, resulting in a colored product with a λmax at 520 nm. The optimum conditions for determining gallic acid were also investigated. Optimizations of the experimental conditions were carried out based on the so-call univariate method. The conditions obtained were 0.6% (w/v) rhodanine, 70% (v/v) ethanol, 0.9 mol L(-1) NaOH, 2.0 mL min(-1) flow rate, 75 μL injection loop and 600 cm mixing tubing length, respectively. Comparative optimizations of the experimental conditions were also carried out by multivariate or simplex optimization method. The conditions obtained were 1.2% (w/v) rhodanine, 70% (v/v) ethanol, 1.2 mol L(-1) NaOH, flow rate 2.5 mL min(-1), 75 μL injection loop and 600 cm mixing tubing length, respectively. It was found that the optimum conditions obtained by the former optimization method were mostly similar to those obtained by the latter method. The linear relationship between peak height and the concentration of gallic acid was obtained over the range of 0.1-35.0 mg L(-1) with the detection limit 0.081 mg L(-1). The relative standard deviations were found to be in the ranges 0.46-1.96% for 1, 10, 30 mg L(-1) of gallic acid (n=11). The method has the advantages of simplicity extremely high selectivity and high precision. The proposed method was successfully applied to the determination of gallic acid in longan samples without interferent effects from other common phenolic compounds that might be present in the longan samples collected in northern Thailand.

  14. Are the Crystal Structures of Enantiopure and Racemic Mandelic Acids Determined by Kinetics or Thermodynamics?

    Science.gov (United States)

    Hylton, Rebecca K; Tizzard, Graham J; Threlfall, Terence L; Ellis, Amy L; Coles, Simon J; Seaton, Colin C; Schulze, Eric; Lorenz, Heike; Seidel-Morgenstern, Andreas; Stein, Matthias; Price, Sarah L

    2015-09-02

    Mandelic acids are prototypic chiral molecules where the sensitivity of crystallized forms (enantiopure/racemic compound/polymorphs) to both conditions and substituents provides a new insight into the factors that may allow chiral separation by crystallization. The determination of a significant number of single crystal structures allows the analysis of 13 enantiopure and 30 racemic crystal structures of 21 (F/Cl/Br/CH3/CH3O) substituted mandelic acid derivatives. There are some common phenyl packing motifs between some groups of racemic and enantiopure structures, although they show very different hydrogen-bonding motifs. The computed crystal energy landscape of 3-chloromandelic acid, which has at least two enantiopure and three racemic crystal polymorphs, reveals that there are many more possible structures, some of which are predicted to be thermodynamically more favorable as well as slightly denser than the known forms. Simulations of mandelic acid dimers in isolation, water, and toluene do not differentiate between racemic and enantiopure dimers and also suggest that the phenyl ring interactions play a major role in the crystallization mechanism. The observed crystallization behavior of mandelic acids does not correspond to any simple "crystal engineering rules" as there is a range of thermodynamically feasible structures with no distinction between the enantiopure and racemic forms. Nucleation and crystallization appear to be determined by the kinetics of crystal growth with a statistical bias, but the diversity of the mandelic acid crystallization behavior demonstrates that the factors that influence the kinetics of crystal nucleation and growth are not yet adequately understood.

  15. DETERMINATION OF Cu, Fe, Mn, Zn AND FREE FATTY ACIDS IN PEQUI OIL

    Directory of Open Access Journals (Sweden)

    Aparecida M. S. Mimura

    2016-06-01

    Full Text Available Pequi (Caryocar brasiliense Camb., a typical fruit of the Brazilian Cerrado, is an important source of micronutrients and fatty acids. In this work, a new approach for the acid digestion (using H2SO4, HNO3 and H2O2 of pequi oil samples and the determination of Cu, Fe, Zn and Mn by flame atomic absorption spectrometry (F AAS was employed. Capillary zone electrophoresis (CZE was used for free fatty acid (FFA determination after simple and fast extraction with heated ethanol. Good results regarding precision (RSD < 10%, in most cases, sensitivity and adequate LOD and LOQ values were obtained. The accuracy was evaluated using spike tests and the recoveries were from 97 to 107%. The analytes were investigated in four different pequi oil samples. Fe was the trace element with the highest concentration (from 1.99 to 10.3 mg/100 g, followed by Zn, Mn and Cu (1.15 to 3.19, 0.42 to 0.91 and 0.31 to 0.56 mg/100 g, respectively. The main FFA found were oleic acid and palmitic acid (1.61 to 10.7 and 0.82 to 2.69 g/100 g, respectively, while linoleic acid (0.50 g/100 g was detected in only one sample. The pequi oil chemical composition showed good characteristics to be used as a food additive, in cosmetic formulations and for traditional medicine.

  16. Flow injection-chemiluminescence determination of ascorbic acid based on luminol–ferricyanide–gold nanoparticles system

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Yong Ping, E-mail: dongyp@ahut.edu.cn [School of chemistry and chemical engineering, Anhui University of Technology, Maanshan, China, 243002 (China); Gao, Ting Ting; Chu, Xiang Feng; Chen, Jun [School of chemistry and chemical engineering, Anhui University of Technology, Maanshan, China, 243002 (China); Wang, Cheng Ming, E-mail: chmwang@ustc.edu.cn [Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, China, 230026 (China)

    2014-10-15

    A novel flow-injection chemiluminescence (CL) method for the determination of ascorbic acid (AA) is proposed, based upon its enhancing effect on the CL reaction of luminol with ferricyanide catalyzed by gold nanoparticles in alkaline solution. Different sizes gold nanoparticles exhibited different catalyzing effect towards luminol CL and 38 nm gold nanoparticles exhibited the best enhancing effect. Under the optimal experimental conditions, a linear relationship was obtained between the CL intensity and the concentration of ascorbic acid in the range of 1.0×10{sup −10}–1.0×10{sup −6} mol L{sup −1}. The detection limit was 2.0×10{sup –11} mol {sup −1} and the relative standard deviation for 1.0×10{sup −6} mol L{sup −1} ascorbic acid was 0.71% (n=10). This method has been successfully applied in the determination of ascorbic acid in several real samples. - Highlights: • Gold nanoparticles could enhance luminol–K{sub 3}Fe(CN){sub 6} CL signal. • 38 nm gold nanoparticles exhibited the best catalyzing effect. • Ascorbic acid could further enhance luminol–K{sub 3}Fe(CN){sub 6}–gold nanoparticles CL. • Ascorbic acid could be detected sensitively based on its enhancing effect.

  17. Determination of sugars, organic acids, aroma components, and carotenoids in grapefruit pulps.

    Science.gov (United States)

    Zheng, Huiwen; Zhang, Qiuyun; Quan, Junping; Zheng, Qiao; Xi, Wanpeng

    2016-08-15

    The composition and content of sugars, organic acids, volatiles and carotenoids, in the pulps of six grapefruit cultivars, were examined by HPLC and GC-MS. The results showed that sucrose was the dominant sugar in grapefruit, making up 40.08-59.68% of the total sugars, and the ratio of fructose to glucose was almost 1:1. Citric acid was the major organic acid and represented 39.10-63.55% of the total organic acids, followed by quininic acid. The ratios of individual sugars and organic acids play an important role in grapefruit taste determination. Monoterpenes and sesquiterpenes were the predominant volatiles in grapefruit, in particular d-limonene and caryophyllene. Caryophyllene, α-humulene, humulen-(v1), β-linalool and tert-butyl 2-methylpropanoate are the characteristic aroma compounds of grapefruit. Although β-carotene is the primary carotenoid in grapefruit, the pulp color is mainly determined by the ratios of zeaxanthin, β-cryptoxanthin and lycopene. Our results provide the first complete chemical characterization of the taste, aroma and color of grapefruit.

  18. Determination of Monochloroacetic Acid in Swimming Pool Water by Ion Chromatography-Conductivity Detection

    Directory of Open Access Journals (Sweden)

    Maria Pythias B. Espino

    2013-02-01

    Full Text Available In this study, an analytical method involving ion chromatography with conductivity detection was developed and optimized for the determination of monochloroacetic acid in swimming pool water. The ion chromatographic method has a detection limit of 0.02 mg L-1 and linear range of 0.05 to 1.0 mg L-1 with correlation coeff icient of 0.9992. The method is reproducible with percent RSD of 0.052% (n=10. The recovery of monochloroacetic acid spiked in different water types (bottled, tap and swimming pool water ranged from 28 to 122%. In dilute solutions, chloride and bromide were simultaneously analyzed along with monochloroacetic acid using the optimized method. Chloride and bromide have detection limits of 0.01 to 0.05 mg L-1, respectively. The usefulness of the ion chromatographic method was demonstrated in the analysis of monochloroacetic acid in swimming pool water samples. In such highly-chlorinated samples, an Ag/H cartridge was used prior to the ion chromatographic determination so as to minimize the signal due to chloride ion. Monochloroacetic acid was detected in concentrations between 0.020 and 0.093 mg L-1 in three of the six swimming pool water samples studied. The presence of monochloroacetic acid in the swimming pool water samples suggests the possible occurrence of other disinfection by-products in these waters.

  19. Determination of Monochloroacetic Acid in Swimming Pool Water by Ion Chromatography-Conductivity Detection

    Directory of Open Access Journals (Sweden)

    Maria Pythias B. Espino

    2013-12-01

    Full Text Available In this study, an analytical method involving ion chromatography with conductivity detection was developed and optimized for the determination of monochloroacetic acid in swimming pool water. The ion chromatographic method has a detection limit of 0.02 mg L-1 and linear range of 0.05 to 1.0 mg L-1 with correlation coeff icient of 0.9992. The method is reproducible with percent RSD of 0.052% (n=10. The recovery of monochloroacetic acid spiked in different water types (bottled, tap and swimming pool water ranged from 28 to 122%. In dilute solutions, chloride and bromide were simultaneously analyzed along with monochloroacetic acid using the optimized method. Chloride and bromide have detection limits of 0.01 to 0.05 mg L-1, respectively. The usefulness of the ion chromatographic method was demonstrated in the analysis of monochloroacetic acid in swimming pool water samples. In such highly-chlorinated samples, an Ag/H cartridge was used prior to the ion chromatographic determination so as to minimize the signal due to chloride ion. Monochloroacetic acid was detected in concentrations between 0.020 and 0.093 mg L-1 in three of the six swimming pool water samples studied. The presence of monochloroacetic acid in the swimming pool water samples suggests the possible occurrence of other disinfection by-products in these waters.

  20. Flow-injection chemiluminescence determination of tryptophan using galangin-potassium permanganate-polyphosphoric acid system

    Institute of Scientific and Technical Information of China (English)

    Hui Chen; Li Li; Min Zhou; Yong Jun Ma

    2008-01-01

    A high sensitive flow-injection chemiluminescence (FI-CL)method for the determination of tryptephan has been developed.The method is based on the chemiluminescence reaction of galangin-potassium perrnanganate-tryptophan in polyphosphoric acid (PPA)media.Under the optimized conditions,tryptophan was determined in the range 0.05-10 μg/mL with the detection limit (30)of 5.0× 10-3 μg/mL.The relative standard deviation (RSD)was 1.0% for 11 replicate determinations of 1.0 μg/mL tryptophan.Three synthetic samples were determined selectively with recoveries in the range from 99.6% to 102.0% in the presence of other amino acids.

  1. Determination of homovanillic acid and vanillylmandelic acid in neuroblastoma screening by stable isotope dilution GC-MS.

    Science.gov (United States)

    Fauler, G; Leis, H J; Huber, E; Schellauf, C; Kerbl, R; Urban, C; Gleispach, H

    1997-05-01

    A method for the quantitative determination of homovanillic acid (HVA) and vanillylmandelic acid (VMA), two metabolites of catecholamines, is presented. The assay is based on gas chromatography/electron impact mass spectrometry. The preparation of 13C-labeled VMA from [13C6]vanillin is described. Together with purchased deuterated HVA the 13C-labeled VMA is used as an internal standard in stable isotope dilution GC/MS. The method involves elution from soaked filter-papers, determination of creatinine content, extraction of HVA and VMA from eluted and urinary samples and derivatization to the di-and tri(trimethylsilyl) derivatives, respectively. The detection limits were found to be 4.0 pg for HVA and 0.8 pg for VMA. The method was applied to the routine determination of urinary HVA and VMA in a range from 5 to 100 ng HVA and VMA per microgram creatinine. The lower limits of pathological concentrations are set at 35 ng micrograms-1 creatinine for HVA and to 20 ng micrograms-1 creatinine for VMA, which are in close correlation with the values from other methods, but with the main advantage of reducing the amount of questionable or elevated results from 6.7% (high-performance liquid chromatography (HPLC) alone) to 0.9% (HPLC and GC/MS).

  2. Determination of fatty acid composition and quality characteristics of oils from palm fruits using solvent extraction

    Science.gov (United States)

    Kasmin, Hasimah; Lazim, Azwan Mat; Awang, Roila

    2015-09-01

    Palm oil contains about 45% of saturated palmitic acid and 39% of mono-unsaturated oleic acid. Investigations made in the past to trace the fatty acid composition in palm revealed that ripeness of fresh fruit bunch (FFB) affect oil composition. However, there is no evidence that processing operations affect oil composition, although different stage of processing does affect the quality of oil extracted. An improved method for sterilizing the oil palm fruits by dry heating, followed by oil extraction has been studied. This method eliminates the use of water, thus, increasing the extraction of lipid soluble. The objective of this study is to determine the possibility production of palm oil with different fatty acid composition (FAC) as well as the changes in quality from conventional milling. The unripe and ripe FFB were collected, sterilized and extracted using different method of solvent extraction. Preliminary data have shown that variation in FAC will also alter the physical and chemical properties of the oil extracted.

  3. Dispersing of Petroleum Asphaltenes by Acidic Ionic Liquid and Determination by UV-Visible Spectroscopy

    Directory of Open Access Journals (Sweden)

    Eshagh Rezaee Nezhad

    2013-01-01

    Full Text Available Nowadays, constructing a mechanism to prevent the aggregation petroleum asphaltenes by the use of new acidic ionic liquids has become of fundamental importance. In this research, 3-(2-carboxybenzoyl-1-methyl-1H-imidazol-3-ium chloride ([CbMIM] [Cl] and other ionic liquids such as [CbMIM]BF4, [HMIM]Cl, [BMIM]Br, and [HMIM]HSO4 were tested. It should be noted that during the experiment the presence of the acidic ionic liquid moiety enhanced interactions between asphaltenes and acidic ionic liquids and it greatly limited asphaltene aggregation. We considered parameters such as temperature, amount of dispersant, effect of water: toluene ratio, the stirring time and effects of other ionic liquids, and determination of concentration of petroleum asphaltenes after dispersing by acidic ionic liquid under various parameters using UV-Visible spectroscopy.

  4. Spectrophotometric method for determination and kinetics of amino acids through their reaction with syringaldehyde

    Science.gov (United States)

    Medien, H. A. A.

    1998-02-01

    A spectrophotometric method is described for the determination of amino acids. The method is based on the reaction between amino acids and syringaldehyde at pH 9.0, by which a color is developed with maximum absorption at 420 nm in aqueous methyl alcohol. The absorption of the product obeys Beer's law within the concentration range of 0.025-0.5 mM of original amino acid. The kinetics of the reaction follows overall second order kinetics, first order in each of the reactants. The rates of the reaction were investigated as a function of pH of the reaction medium and structure of the amino compounds. Logarithms of the second-order rate constants increased with amino acid anion concentration as the pH was increased. The mechanisms of the reaction have been discussed.

  5. Method for determination of fatty acids in bovine colostrum using GC-FID.

    Science.gov (United States)

    Yurchenko, S; Sats, A; Poikalainen, V; Karus, A

    2016-12-01

    Bovine colostrum is potentially valuable source of essential fatty acids (FAs), but so far only few studies have made the effort to estimate FA composition of this potential resource. The aim of current research was to fill this gap with selecting and validating an accurate procedure for the analysis of the composition of the FAs in bovine colostrum. We used colostrum samples of Holstein-Friesian cattle from Märja experimental farm as a test material. The validated method includes derivatization, in which FAs are sent through esterification with the acidic catalyst boron trifluoride. Formed methyl esters of fatty acids (FAMEs) were analysed using GC-FID. The obtained LOD and the LOQ of FAMEs were 0.11-0.68 and 0.37-2.27ppm, respectively. The analysis of fortified samples showed very good and similar recoveries, indicating that the method proposed here can be routinely used for determination and investigation of the fatty acids in dairy products.

  6. Determination of salicylic acid by HPLC in plasma and saliva from children with juvenile chronic arthritis.

    Science.gov (United States)

    Legaz, M E; Acitores, E; Valverde, F

    1992-12-01

    A high performance liquid chromatography (HPLC) method has been developed for measuring salicylic acid in the plasma and saliva of children with juvenile chronic arthritis (JCA). Samples were extracted with diethyl ether and, after drying, redissolved in methanol to be chromatographed. Quantitation of salicylic acid was performed by reverse phase HPLC on a spherisorb ODS-2 column, using methanol: water: acetic acid as mobile phase. Phenolic was monitored by absorbance at 237 nm. Linearity between the amount of mass injected and the response in the detector was determined. This method was applied to compare concentrations of salivary and plasma salicylic acid. The method also permitted the quantitation of salivary salicylate as a non-invasive, indirect method for monitoring the concentration of plasma salicylate in patients with JCA.

  7. Amino acids analysis by total neutron cross-sections determinations: part V

    Energy Technology Data Exchange (ETDEWEB)

    Voi, Dante L.; Ferreira, Francisco de O., E-mail: dante@ien.gov.br, E-mail: fferreira@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Rocha, Helio F. da, E-mail: helionutro@hotmail.com [Universidade Federal do Rio de Janeiro (IPPMG/UFRJ), Rio de Janeiro, RJ (Brazil). Instituto de Pediatria

    2013-07-01

    Total neutron cross-sections of twenty essential and non-essential amino acids to human were determined using crystal spectrometer installed on the Argonauta reactor of IEN (Instituto de Engenharia Nuclear (CNEN-RJ) and compared with data generated by parceling and grouping methodologies developed at this institution. For each amino acid was calculated the respective neutron cross-section by molecular structure, conformation and chemistry analysis. The results obtained for eighteen of twenty amino acids confirm the specifications and product formulations indicated by manufactures. These initial results allow to build a neutron cross-sections database as part of quality control of the amino supplied to hospitals for production of nutriments for parenteral or enteral formulations used in critical patients dependent on artificial feed, and for application in future studies of structure and dynamics for more complex molecules, including proteins, enzymes, fatty acids, membranes, organelles and other cell components. (author)

  8. Spectrophotometric determination of acidity constants of some macrolides in acetonitrile-water binary mixtures.

    Science.gov (United States)

    Sanli, Senem; Sanli, Nurullah; Alsancak, Güleren

    2010-12-01

    The acidity constants of eight macrolides (erythromycin, roxithromycin, oleandomycin, azithromycin, josamycin, tylosin tartrate, tilmicosin and spiramycin) have been determined in acetonitrile-water binary mixtures (30%, 40% and 50% (v/v)) by spectrophotometric method. The pKa's available in literature determined by various methods are compiled in comparison with the value of this work. These results are expected to essentially facilitate the research on occurrence, fate and effects, analysis method development, and control of antibiotics in various treatment occurrences.

  9. A method for determining thermophysical properties of organic material in aqueous solutions: Succinic acid

    Science.gov (United States)

    Riipinen, I.; Svenningsson, B.; Bilde, M.; Gaman, A.; Lehtinen, K. E. J.; Kulmala, M.

    2006-12-01

    A method for determining evaporation rates and thermodynamic properties of aqueous solution droplets is introduced. The method combines evaporation rate measurements using modified TDMA technique with data evaluation using an accurate evaporation model. The first set of data has been collected and evaluated for succinic acid aqueous solution droplets. Evaporation rates of succinic acid solution droplets have been measured using a TDMA system at controlled relative humidity (65%) and temperature (298 K). A temperature-dependent expression for the saturation vapour pressure of pure liquid phase succinic acid at atmospheric temperatures has been derived by analysing the evaporation rate data with a numerical model. The obtained saturation vapour pressure of liquid phase succinic acid is ln( p) = 118.41 - 16204.8/ T - 12.452ln( T). The vapour pressure is in unit of Pascal and the temperature in Kelvin. A linear expression for the enthalpy of vaporization for liquid state succinic acid is also presented. According to the results presented in the following, a literature expression for the vapour pressure of liquid phase succinic acid defined for temperatures higher than 461 K [Yaws, C.L., 2003. Yaws' Handbook of Thermodynamic and Physical Properties of Chemical Compounds, Knovel] can be extrapolated to atmospheric temperatures with very good accuracy. The results also suggest that at 298 K the mass accommodation coefficient of succinic acid is unity or very close to unity.

  10. Paper-based electroanalytical devices for in situ determination of salicylic acid in living tomato leaves.

    Science.gov (United States)

    Sun, Li-Jun; Feng, Qiu-Mei; Yan, Yong-Feng; Pan, Zhong-Qin; Li, Xiao-Hui; Song, Feng-Ming; Yang, Haibing; Xu, Jing-Juan; Bao, Ning; Gu, Hai-Ying

    2014-10-15

    Detection of phytohormones in situ has gained significant attention due to their critical roles in regulating developmental processes and signaling for defenses in plants at low concentration. As one type of plant hormones, salicylic acid has recently been found to be one of pivotal signal molecules for physiological behaviors of plants. Here we report the application of paper-based electroanalytical devices for sensitively in situ detection of salicylic acid in tomato leaves with the sample volume of several microliters. Specifically, disposable working electrodes were fabricated by coating carbon tape with the mixture of multiwall carbon nanotubes and nafion. We observed that the treatment of the modified carbon tape electrodes with oxygen plasma could significantly improve electrochemical responses of salicylic acid. The tomato leaves had a punched hole of 1.5mm diameter to release salicylic acid with minor influence on continuous growth of tomatoes. By incorporating the tomato leaf with the paper-based analytical device, we were able to perform in situ determination of salicylic acid based on its electrocatalytic oxidation. Our experimental results demonstrated that the amounts of salicylic acid differed statistically in normal, phytoene desaturase (PDS) gene silent and diseased (infected by Botrytis cinerea) tomato leaves. By quantifying salicylic acid at the level of several nanograms in situ, the simple paper-based electroanalytical devices could potentially facilitate the study of defense mechanism of plants under biotic and abiotic stresses. This study might also provide a sensitive method with spatiotemporal resolution for mapping of chemicals released from living organisms.

  11. Rapid determination of amino acids in biological samples using a monolithic silica column.

    Science.gov (United States)

    Song, Yanting; Funatsu, Takashi; Tsunoda, Makoto

    2012-05-01

    A high-performance liquid chromatography method in which fluorescence detection is used for the simultaneous determination of 21 amino acids is proposed. Amino acids were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) and then separated on a monolithic silica column (MonoClad C18-HS, 150 mm×3 mm i.d.). A mixture of 25 mM citrate buffer containing 25 mM sodium perchlorate (pH 5.5) and acetonitrile was used as the mobile phase. We found that the most significant factor in the separation was temperature, and a linear temperature gradient from 30 to 49°C was used to control the column temperature. The limits of detection and quantification for all amino acids ranged from 3.2 to 57.2 fmol and 10.8 to 191 fmol, respectively. The calibration curves for the NBD-amino acid had good linearity within the range of 40 fmol to 40 pmol when 6-aminocaproic acid was used as an internal standard. Using only conventional instruments, the 21 amino acids could be analyzed within 10 min. This method was found to be suitable for the quantification of the contents of amino acids in mouse plasma and adrenal gland samples.

  12. Selective extraction and determination of chlorogenic acid in fruit juices using hydrophilic magnetic imprinted nanoparticles.

    Science.gov (United States)

    Hao, Yi; Gao, Ruixia; Liu, Dechun; He, Gaiyan; Tang, Yuhai; Guo, Zengjun

    2016-06-01

    In this paper, the novel hydrophilic magnetic molecularly imprinted nanoparticles were developed for selective separation and determination of chlorogenic acid in aqueous fruit juices. The polymers were prepared by using amino-functionalized magnetic nanoparticles as carriers, branched polyethyleneimine as functional monomer, and chlorogenic acid as template molecule. Branched polyethyleneimine with abundant active amino groups could react with template sufficiently, and its unique dendritic structure may amplify the number of the imprinted cavities. Meanwhile, it would improve the hydrophilicity of imprinted materials for attaining high extraction efficiency. The resulted polymers exhibit fast kinetics, high adsorption capacity, and favorable selectivity. In addition, the obtained nanoparticles were used as solid-phase extraction sorbents for selective isolation and determination of chlorogenic acid in peach, apple, and grape juices (0.92, 4.21, and 0.75 μg mL(-1), respectively).

  13. New method for spectrophotometric determination of quinones and barbituric acid through their reaction. A kinetic study

    Science.gov (United States)

    Medien, H. A. A.

    1996-11-01

    A new and sensitive spectrophotometric method is described for the determination of p-benzoquinone, p-chloranil and 1.4-naphthoquinone. The method is based on the reaction between quinones and barbituric acid, by which a color is developed with maximum absorption between 485 and 555 nm in 50% methyl alcohol-water mixture. The absorption of the product obeys Beer's law within the concentration range 0.025-05 mM of orginal quinone. The kinetics of the reaction between p-benzoquinone and barbituric acid was studied in a range of methyl alcohol-water mixtures. The reaction follows overall second order kinetics, first order in each of the reactants. The rate increases with increasing dielectric constant. The method was applied for determination of barbituric acid with p-benzoquinone in the concentration range of 0.025-0.345 mM. Other barbiturates do not interfere.

  14. Determination of Free Fatty Acids and Triglycerides by Gas Chromatography Using Selective Esterification Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kail, Brian W; Link, Dirk D; Morreale, Bryan D

    2012-11-01

    A method for selectively determining both free fatty acids (FFA) and triacylglycerides (TAGs) in biological oils was investigated and optimized using gas chromatography after esterification of the target species to their corresponding fatty acid methyl esters (FAMEs). The method used acid catalyzed esterification in methanolic solutions under conditions of varying severity to achieve complete conversion of more reactive FFAs while preserving the concentration of TAGs. Complete conversion of both free acids and glycerides to corresponding FAMEs was found to require more rigorous reaction conditions involving heating to 120°C for up to 2 h. Method validation was provided using gas chromatography–flame ionization detection, gas chromatography–mass spectrometry, and liquid chromatography–mass spectrometry. The method improves on existing methods because it allows the total esterified lipid to be broken down by FAMEs contributed by FFA compared to FAMEs from both FFA and TAGs. Single and mixed-component solutions of pure fatty acids and triglycerides, as well as a sesame oil sample to simulate a complex biological oil, were used to optimize the methodologies. Key parameters that were investigated included: HCl-to-oil ratio, temperature and reaction time. Pure free fatty acids were found to esterify under reasonably mild conditions (10 min at 50°C with a 2.1:1 HCl to fatty acid ratio) with 97.6 ± 2.3% recovery as FAMEs, while triglycerides were largely unaffected under these reaction conditions. The optimized protocol demonstrated that it is possible to use esterification reactions to selectively determine the free acid content, total lipid content, and hence, glyceride content in biological oils. This protocol also allows gas chromatography analysis of FAMEs as a more ideal analyte than glyceride species in their native state.

  15. Determination of free fatty acids and triglycerides by gas chromatography using selective esterification reactions.

    Science.gov (United States)

    Kail, Brian W; Link, Dirk D; Morreale, Bryan D

    2012-01-01

    A method for selectively determining both free fatty acids (FFA) and triacylglycerides (TAGs) in biological oils was investigated and optimized using gas chromatography after esterification of the target species to their corresponding fatty acid methyl esters (FAMEs). The method used acid catalyzed esterification in methanolic solutions under conditions of varying severity to achieve complete conversion of more reactive FFAs while preserving the concentration of TAGs. Complete conversion of both free acids and glycerides to corresponding FAMEs was found to require more rigorous reaction conditions involving heating to 120°C for up to 2 h. Method validation was provided using gas chromatography-flame ionization detection, gas chromatography-mass spectrometry, and liquid chromatography-mass spectrometry. The method improves on existing methods because it allows the total esterified lipid to be broken down by FAMEs contributed by FFA compared to FAMEs from both FFA and TAGs. Single and mixed-component solutions of pure fatty acids and triglycerides, as well as a sesame oil sample to simulate a complex biological oil, were used to optimize the methodologies. Key parameters that were investigated included: HCl-to-oil ratio, temperature and reaction time. Pure free fatty acids were found to esterify under reasonably mild conditions (10 min at 50°C with a 2.1:1 HCl to fatty acid ratio) with 97.6 ± 2.3% recovery as FAMEs, while triglycerides were largely unaffected under these reaction conditions. The optimized protocol demonstrated that it is possible to use esterification reactions to selectively determine the free acid content, total lipid content, and hence, glyceride content in biological oils. This protocol also allows gas chromatography analysis of FAMEs as a more ideal analyte than glyceride species in their native state.

  16. Fluorimetric determination of phytic acid in urine based on replacement reaction.

    Science.gov (United States)

    Chen, Yingyu; Chen, Jingwen; Ma, Kang; Cao, Shuhong; Chen, Xiaoqing

    2007-12-19

    A sensitive fluorimetric method for determination of phytic acid in human urine samples was described. The method was based on a fluorimetric replacement reaction, in which the added phytic acid replaced the Cu2+ ion from Cu2+-gelatin complex, liberating the fluorescent gelatin molecule. The fluorescence of the solution was accordingly recovered proportionally to the amount of the foreign phytic acid. The excitation wavelength was 273.5 nm and the characteristic emission wavelength was 305.0 nm, respectively. The calibration graph was obtained by plotting the recovered fluorescent intensity at maximum 305.0 nm against the added standard phytic acid, and was divided into two sections. One section was linear over the range of 0.40-2.40 mg L(-1) with a linear regression equation of I(f) = -0.895+15.146c (R2 > 0.9993), and the other over the range of 2.40-9.20 mg L(-1) with a linear regression equation of I(f) = -29.526+26.113c (R2 > 0.9996), respectively. The relative standard deviation (R.S.D.) at 95% confidence degree for a 2.0 mg L(-1) of standard phytic acid within 1 month was less than 1.26% (n = 5), indicating the procedure is reproducible. The detection and the quantification limits of phytic acid were estimated to be 0.23 and 0.40 mg L(-1), respectively. The proposed method was applied to the determination of phytic acid in urine samples and the found concentrations of phytic acid in urine were in the range of 0.49-0.75 mg L(-1) with recoveries of 96.2-108.8%. Comparison of the obtained results with the reported HPLC was performed, indicating the proposed method was reliable.

  17. Flow injection chemiluminescence determination of loxoprofen and naproxen with the acidic permanganate-sulfite system

    Institute of Scientific and Technical Information of China (English)

    Li-Juan Wang; Yu-Hai Tang; Yang-Hao Liu

    2011-01-01

    A novel flow injection chemiluminescence(CL)method for the determination of loxoprofen and naproxen was proposed based on the CL system of KMnO4 and Na2SO3 in acid media.The CL intensity of KMnO4-Na2SO3 was greatly enhanced in the presence of loxoprofen a

  18. Interference of flavonoids with enzymatic assays for the determination of free fatty acid and triglyceride levels

    NARCIS (Netherlands)

    Hoek-van den Hil, E.F.; Beekmann, K.; Keijer, J.; Hollman, P.C.H.; Rietjens, I.; Schothorst, van E.M.

    2012-01-01

    Flavonoids are bioactive food compounds with potential lipid-lowering effects. Commercially available enzymatic assays are widely used to determine free fatty acid (FFA) and triglyceride (TG) levels both in vivo in plasma or serum and in vitro in cell culture medium or cell lysate. However, we have

  19. Amino Acid Profile as a Feasible Tool for Determination of the Authenticity of Fruit Juices

    Directory of Open Access Journals (Sweden)

    Mostafa Asadpoor

    2014-12-01

    Full Text Available Purpose: Fruit juice is a nutrient rich food product with a direct connection to public health. The purpose of this research was to determine the amino acid profile of juices and provide a quick and accurate indicator for determining their authenticity. Methods: The method of analysis was HPLC with fluorescence detector and pre-column derivatization by orthophtaldialdehyde (OPA. Sixty-six samples of fruit juices were analyzed, and fourteen amino acids were identified and determined in the sampled fruit juices. The fruit samples used for this analysis were apples, oranges, cherry, pineapple, mango, apricot, pomegranate, peach and grapes. Results: The results showed that 32% of samples tested in this study had a lower concentrate percentage as compared to that of their labels and/or other possible authenticity problems in the manufacturing process. The following samples showed probable adulteration: four cherry juice samples, two pomegranate juice samples, one mango, three grape, four peach, seven orange, two apple and one apricot juice samples. Conclusion: In general, determining the amount of amino acids and comparing sample amino acids profiles standard values seems to be an indicator for quality control. This method can the regulatory agencies with a tool, to help produce a healthier The aim of this study is the analytical control of the fruit juice composition is becoming an important issue, and HPLC can provide an important and essential tool for more accurate research as well as for routine analysis.

  20. Simple Method to Determine the Partition Coefficient of Naphthenic Acid in Oil/Water

    DEFF Research Database (Denmark)

    Bitsch-Larsen, Anders; Andersen, Simon Ivar

    2008-01-01

    The partition coefficient for technical grade naphthenic acid in water/n-decane at 295 K has been determined (K-wo = 2.1 center dot 10(-4)) using a simple experimental technique with large extraction volumes (0.09 m(3) of water). Furthermore, nonequilibrium values at different pH values are prese...

  1. Effect of intraarticular osmic acid on synovial membrane volume and inflammation, determined by magnetic resonance imaging

    DEFF Research Database (Denmark)

    Østergaard, Mikkel; Stoltenberg, M; Gideon, P;

    1995-01-01

    The changes in MR-determined synovial membrane volume, early synovial enhancement, and cartilage and bone erosions after osmic acid knee synovectomy were studied. Gadolinium-DTPA enhanced magnetic resonance imaging (MRI) of 18 knees with persistent arthritis was performed before and 1 month after...... treatment. The synovial membrane volume was significantly reduced (median -52%) in all 9 patients brought into clinical remission (p

  2. Development of gamma spectrometric method for the determination of thorium in phosphoric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Mirashi, N.N.; Chaudhury, S.; Aggarwal, S.K. [Fuel Chemistry Div., Bhabha Atomic Research Centre, Mumbai (India)

    2010-07-01

    Gamma spectrometric determination of thorium in sintered thoria dissolved in strong phosphoric acid was studied using a high purity germanium (HPGe) detector. {sup 232}Th was determined using the highly abundant (27%) gamma ray (911.4 keV) emitted by its daughter {sup 228}Ac. The count rates in peak regions were plotted against the amount of thorium present in thorium nitrate working standard solution to obtain a calibration curve and the extent of thoria dissolved in 88% phosphoric acid was determined. Further studies on determination of thorium were carried out using thorium phosphate solutions, instead of using thorium nitrate working standard solutions. The solution of thorium phosphate obtained after quantitative dissolution of thoria in 88% phosphoric acid was also found to give a linear calibration curve at 911.4 keV. Using the calibration curves, expected count rates for thorium in sintered thoria dissolved in 88% phosphoric acid were calculated and were in good agreement ({+-}3%) with the observed count rates. (orig.)

  3. Determination of Distribution Coefficient of Nitrous Acid and Evaluation of Influential Factors

    Institute of Scientific and Technical Information of China (English)

    ZHU; Li-yang; CHEN; Yan-xin; TANG; Hong-bin; HE; Hui

    2013-01-01

    Nitrous acid is inevitably present in Purex process,thus,it is desired to build a HNO2 distribution model which could be incorporated into Purex computer simulation code.In this work base titration and diazotization-coupling reaction was used to determine the concentration of HNO3 and HNO2 in both

  4. Determination of organophosphorus acids by thermo-spray liquid chromatography-mass spectrometry

    NARCIS (Netherlands)

    Wils, E.R.J.; Hulst, A.G.

    1988-01-01

    The determination of thirteen organophosphorus acids, hydrolysis products of nerve agents and pesticides, by a combination of ion-pair liquid chromatography on a reversed-phase C18 column and thermospray mass spectrometry was investigated. Ammonium acetate and three tetraalkylammonium salts with dif

  5. Spectrophotometric method for the determination of sorbic acid in various food samples with iron(III) and 2-thiobarbituric acid as reagents.

    Science.gov (United States)

    Lau, O W; Luk, S F; Lam, R K

    1989-02-01

    A simple, rapid and accurate spectrophotometric method has been developed for the determination of sorbic acid in various food samples based on the oxidation of sorbic acid by iron(III) at 100 degrees C to malonaldehyde, which then reacts with 2-thiobarbituric acid to form a reddish brown product. The optimum experimental conditions for colour development have been assessed. Absorbance measurements were made at 529 nm in the presence of 0.4% m/V citric acid. The calibration graph was linear for 0-6 micrograms ml-1 of sorbic acid with a slope of 0.131 A micrograms-1 ml. The recoveries of sorbic acid at concentrations of 164-557 micrograms ml-1 ranged from 96 to 103%. The relative standard deviations of ten replicate determinations of sorbic acid in a synthetic cream soda sample spiked with 573 micrograms ml-1 of sorbic acid and in an onion juice sample containing 82 micrograms ml-1 of sorbic acid were 1.6 and 1.9%, respectively. Interferences from several common food additives can be minimised by extracting sorbic acid with diethyl ether and then back-extracting the acid with sodium hydrogen carbonate. The method has been applied successfully to the determination of sorbic acid in a wide range of food samples including beverages, cake, cake mate, garlic bread sprinkle, onion juice, oyster flavoured sauce and grenadine syrup.

  6. Quantitative determination of carboxylic acids, amino acids, carbohydrates, ethanol and hydroxymethylfurfural in honey by (1)H NMR.

    Science.gov (United States)

    del Campo, Gloria; Zuriarrain, Juan; Zuriarrain, Andoni; Berregi, Iñaki

    2016-04-01

    A method using (1)H NMR spectroscopy has been developed to quantify simultaneously thirteen analytes in honeys without previous separation or pre-concentration steps. The method has been successfully applied to determine carboxylic acids (acetic, formic, lactic, malic and succinic acids), amino acids (alanine, phenylalanine, proline and tyrosine), carbohydrates (α- and β-glucose and fructose), ethanol and hydroxymethylfurfural in eucalyptus, heather, lavender, orange blossom, thyme and rosemary honeys. Quantification was performed by using the area of the signal of each analyte in the honey spectra, together with external standards. The regression analysis of the signal area against concentration plots, used for the calibration of each analyte, indicates a good linearity over the concentration ranges found in honeys, with correlation coefficients higher than 0.985 for the thirteen quantified analytes. The recovery studies give values over the 93.7-105.4% range with relative standard deviations lower than 7.4%. Good precision, with relative standard deviations over the range of 0.78-5.21% is obtained.

  7. Methods for extraction and determination of phenolic acids in medicinal plants: a review.

    Science.gov (United States)

    Arceusz, Agnieszka; Wesolowski, Marek; Konieczynski, Pawel

    2013-12-01

    Phenolic acids constitute a group of potentially immunostimulating compounds. They occur in all medicinal plants and are widely used in phytotherapy and foods of plant origin. In recent years, phenolic acids have attracted much interest owing to their biological functions. This paper reviews the extraction and determination methods of phenolic acids in medicinal plants over the last 10 years. Although Soxhlet extraction and ultrasonic assisted extraction (UAE) are commonly used for the extraction of phenolic acids from plant materials, alternative techniques such as supercritical fluid extraction (SFE), and accelerated solvent extraction (ASE) can also be used. After extraction, phenolic acids are determined usually by liquid chromatography (LC) owing to the recent developments in this technique, especially when it is coupled with mass spectrometry (MS). Also detection systems are discussed, including UV-Vis, diode array, electrochemical and fluorimetric. Other popular techniques for the analysis of this group of secondary metabolites are gas chromatography coupled with mass spectrometry (GC-MS) and capillary electrophoresis (CE).

  8. EXTRACTION, QUANTIFICATION, AND MOLAR MASS DETERMINATION OF HYALURONIC ACID EXTRACTED FROM CHICKEN CREST

    Directory of Open Access Journals (Sweden)

    C. S. ROSA

    2008-11-01

    Full Text Available

    Hyaluronic acid (HA is part of the connective tissue. The polymer is composed of alternating units of ß-d-glucuronic acid and N-acetyl-ß-d-glucosamine linked, respectively, via 1-3 and 1-4 bonds. The chicken crest is one of the richest tissues in this polysaccharide. Since Brazil is one of the main chicken exporters in the world, the utilization of the crests of abated animals for the HA obtaining is particularly attractive. The present work sought to extract HA from chicken crest and to determine the molar mass of the extracted acid. Extraction was accomplished by proteolytic digestion with papain during 24 h at 60oC, followed by precipitation with cetylpyridinium chloride (CPC. Hexuronic acid content was determined via the carbazole method, the intrinsic viscosity was measured using the ball viscosimeter, and the molar mass was calculated by extrapolating the calibration line to zero. In addition, qualitative infrared spectroscopy was carried out on the sample using the Bomem MB spectrophotometer. The results show that the extraction method was effective: the extracted acid possesses a large molecular mass, and the extract contains a signifi cant amount of HA.

  9. Determination of caffeic acid in root and rhizome of Black cohosh (Cimicifuga racemosa (L. Nutt.

    Directory of Open Access Journals (Sweden)

    Zapala Karolina

    2014-06-01

    Full Text Available Cimicifuga racemosa, is a plant with a diverse and long history of medicinal use. Caffeic acid, bioactive compound, which often occurs with other polyphenols can influence the biological activity of this plant. The aim of our work was quantitative analysis of caffeic acid in roots and rhizomes of two varieties of C. racemosa. Analysis was performed by HPLC method. The extracts were separated on C18 reversed-phase column using mixture of methanol, water and formic acid (25:75:0.5 v/v/v as a mobile phase. The flow rate of eluent was 1.0 ml·min-1. The obtained validation parameters such as linearity, linear regression equation and precision expressed as a relative standard deviation were adequate for quantitative determination. Caffeic acid was found in all tested extracts. The highest total amount of caffeic acid was determined in C. racemosa var. racemosa (255.3 μg·g-1 while its concentration in C. racemosa var. cordifolia was significantly lower (213.0 μg·g-1.

  10. Simultaneous determination of the concentrations of isoproterenol, uric acid, and folic acid in solution using a novel nanostructurebased electrochemical sensor

    Institute of Scientific and Technical Information of China (English)

    Mohammad Mazloum-Ardakani; Fariba Sabaghian; Alireza Khoshroo; Hossein Naeimi

    2014-01-01

    A carbon paste electrode modified with 2-((7-(2,5- dihydrobenzylideneamino)heptylimino)methyl) benzene-1,4-diol (DHB) and carbon nanotubes were used to simultaneously determine the concen-trations of isoproterenol (IP), uric acid (UA), and folic acid (FA) in solution. First, cyclic voltammetry was used to investigate the redox properties of the modified electrode at various scan rates. Next, the mediated oxidation of IP at the modified electrode is described. At the optimum pH of 7.0, the oxidation of IP occurs at a potential about 90 mV less than that of an unmodified carbon paste elec-trode. Based on the results of differential pulse voltammetry (DPV), the oxidation of IP showed a dynamic range between 10 and 6000 μmol/L, and a detection limit of 1.24 µmol/L. Finally, DPV was used to simultaneously determine the concentrations of IP, UA, and FA in solution at the modified electrode.

  11. Voltammetric determination of chlorogenic acid in pharmaceutical products using poly(aminosulfonic acid modified glassy carbon electrode

    Directory of Open Access Journals (Sweden)

    Mingyong Chao

    2014-12-01

    Full Text Available In this work, a poly(aminosulfonic acid modified glassy carbon electrode was fabricated and the electrochemical behavior of chlorogenic acid (CGA was studied by cyclic voltammetry. Compared with a bare glassy carbon electrode, the modified electrode exhibits excellent catalytic effect on the electrochemical redox of CGA. Utilizing this catalytic effect, a sensitive and selective electrochemical method for the determination of CGA was developed. The analytical parameters were optimized. Under the optimized conditions, the oxidation peak current is linearly proportional to the concentration of CGA in the range from 4.00 × 10−7 to 1.20 × 10−5 mol/L and the detection limit is 4.00 × 10−8 mol/L. Further, the performance of the proposed method has been validated in terms of linearity (r = 0.9995, recovery (96.3–102.8%, reproducibility (RSD < 4.0%, n = 6 and robustness. The developed method has been successfully applied for the determination of CGA in a variety of pharmaceutical products.

  12. Multi-elemental analysis of atmospheric pollutants and determination of particle size using the PIXE method, a cascade impactor and a filter unit constructed in Mexico; Analisis multielemental de contaminantes atmosfericos y determinacion de tamano de particula utilizando el metodo PIXE, un impactor de cascada y una unidad de filtro construidos en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Aldape U, F. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1989-01-15

    This work presents: 1) The methodology and the experimental conditions of the PIXE technique so that it is used as a better option inside the analytical methods in aerosols studies, 2) The development, tests and applications of a cascade impactor of the Batelle type built to determine particle size to use it jointly with the mentioned technique in the determination of the elements concentration according to its size.By this way is fulfilled with the first goal of this extensive project. (Author)

  13. GC determination of fatty acids in green beans grown in Galicia (N.W. Spain

    Directory of Open Access Journals (Sweden)

    López Hernández, J.

    1996-06-01

    Full Text Available The concentrations of lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, arachidic acids in green beans (Phaseolus vulgaris L. grown in Galicia (N.W. Spain were determinated by capillary gas chromatography (GC. Palmitic acid was the most abundant fatty acid component (113 mg/100 g. of lyophilizate; 35.2% of total fatty acid content, followed by linolenic acid (23.1% and linoleic acid (21.6%.

    Se determinaron, mediante cromatografía gaseosa, las concentraciones de ácidos láurico, mirístico, palmítico, palmitoleico, esteárico, oieico, linoleico, linolénico y araquídico en judías verdes producidas en Galicia (N.O. España. El ácido palmítico fue el más abundante (113 mg/100 g. de liofilizado; 35,2% del contenido total de ácidos grasos, seguido por los ácidos linolénico (23,1% y linoleico (21,6%.

  14. Micellar LC Separation of Sesquiterpenic Acids and Their Determination in Valeriana officinalis L. Root and Extracts

    Directory of Open Access Journals (Sweden)

    Artem U. Kulikov

    2012-01-01

    Full Text Available A simple micellar liquid chromatography (MLC method was developed and validated according to ICH Guidelines for the determination of sesquiterpenic acids (valerenic, hydroxyvalerenic, and acetoxyvalerenic acids in root and rhizome extract from Valeriana officinalis L. and valerian dry hydroalcoholic extract. Samples were analyzed on Nucleosil C18 column (150mm×4.6mm, 5 μm using an isocratic mobile phase which consisted of Brij 35 (5% (w/v aqueous solution; pH 2.3±0.1 by phosphoric acid and 1-butanol (6% (v/v; UV detection was at 220 nm. Micellar mobile phase using allows to fully separate valerenic acids within 25 minutes. Linearity for hydroxyvalerenic, acetoxyvalerenic, and valerenic acids was 1.9–27.9, 4.2–63.0, and 6.1–91·3 μg.mL−1, and limit of detection was 0.14, 0.037, and 0.09 μg·mL−1, respectively. Intraday and interday precisions were not less than 2% for all investigated compounds. The proposed method was found to be reproducible and convenient for quantitative analysis of sesquiterpenic acids in valerian root and related preparations.

  15. Chromatographic method for determination of the free amino acid content of chamomile flowers

    Directory of Open Access Journals (Sweden)

    Xiaoli Ma

    2015-01-01

    Full Text Available Objective: To determine the free amino acid contents of chamomile flowers using reverse-phase high-performance column chromatography preceded by pre-column derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC, and to determine the reliability of this method. Materials and Methods: Derivatization with reconstituted AQC was used to prepare the samples and standards for injection into the chromatography column. The peaks were analyzed by fluorescence detection (λ excitation, 250 nm; λ emission, 395 nm. Results: Alanine, proline, and leucine were the most abundant amino acids, whereas tyrosine and methionine were the least abundant. The linearity of the method was found to be good with amino acid concentrations of 0.012-0.36 μM. The precision was 0.05-1.36%; average recovery, 91.12-129.41%; and limit of detection, 0.006-0.058 μM. Conclusion: The method is reliable for determining the free amino acid content of different types of chamomile flowers.

  16. Spectrophotometric determination of thioctic (a-Aipoic acid in water and pharmaceutical preparations

    Directory of Open Access Journals (Sweden)

    ZAGORKA KORICANAC

    2007-01-01

    Full Text Available A spectrophotometric method is described for the assay of thioctic acid. The method is based on the reaction between the drug and palladium(II chloride. In this reaction, a yellow-coloured, water soluble product with a 1:1 stoichiometric ratio and an absorption maximum at 365 nm was formed. The stability of the formed complex depends on various factors (pH, reaction time, concentration of reagents, ionic strength. Based on these findings, a new method is suggested for the spectrophotometric determination of thioctic acid in pharmaceutical formulations. This method is simple, sensitive and reproducible.

  17. Fast mass spectrometry-based enantiomeric excess determination of proteinogenic amino acids.

    Science.gov (United States)

    Fleischer, Heidi; Thurow, Kerstin

    2013-03-01

    A rapid determination of the enantiomeric excess of proteinogenic amino acids is of great importance in various fields of chemical and biologic research and industries. Owing to their different biologic effects, enantiomers are interesting research subjects in drug development for the design of new and more efficient pharmaceuticals. Usually, the enantiomeric composition of amino acids is determined by conventional analytical methods such as liquid or gas chromatography or capillary electrophoresis. These analytical techniques do not fulfill the requirements of high-throughput screening due to their relative long analysis times. The method presented allows a fast analysis of chiral amino acids without previous time consuming chromatographic separation. The analytical measurements base on parallel kinetic resolution with pseudoenantiomeric mass tagged auxiliaries and were carried out by mass spectrometry with electrospray ionization. All 19 chiral proteinogenic amino acids were tested and Pro, Ser, Trp, His, and Glu were selected as model substrates for verification measurements. The enantiomeric excesses of amino acids with non-polar and aliphatic side chains as well as Trp and Phe (aromatic side chains) were determined with maximum deviations of the expected value less than or equal to 10ee%. Ser, Cys, His, Glu, and Asp were determined with deviations lower or equal to 14ee% and the enantiomeric excess of Tyr were calculated with 17ee% deviation. The total screening process is fully automated from the sample pretreatment to the data processing. The method presented enables fast measurement times about 1.38 min per sample and is applicable in the scope of high-throughput screenings.

  18. Determination of Kr-85 in environmental samples and gaseous effluents from nuclear industries using the standard method; Aplicacion del metodo de concentracion separacion y medida radiactiva por centelleo liquido de Kr-85 en muestras ambientales y en efluentes gaseosos de la industria nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Heras, M. c.; Perez, M. M.

    1983-07-01

    The determination of the Kr-85 activity in environmental samples and gaseous effluents from Spanish Nuclear Power Stations is described. The method employed has been published elsewhere. The determinations has been carried out in environmental samples token at JEN Laboratories (Madrid) and the Nuclear Power Stations, Jose Cabrera (Zorita), Garona and Vandellos. Also samples of gaseous effluents of the three plants has been analyzed. Values of the Kr-85 environmental background activity in the Almaraz Nuclear Power Stations, has been determined, before the beginning of its nuclear activity. In this paper the sampling equipment used is described and the values found of Kr-85 activity in all the samples in given. (Author) 29 refs.

  19. Determination of dopamine in presence of ascorbic acid and uric acid using poly (Spands Reagent) modified carbon paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Veera Manohara Reddy, Y.; Prabhakara Rao, V.; Vijaya Bhaskar Reddy, A.; Lavanya, M.; Venu, M.; Lavanya, M.; Madhavi, G., E-mail: gmchem01@gmail.com

    2015-12-01

    In this paper, we have fabricated a modified carbon paste electrode (CPE) by electropolymerisation of spands reagent (SR) onto surface of CPE using cyclic voltammetry (CV). The developed electrode was abbreviated as poly(SR)/CPE and the surface morphology of the modified electrode was studied by using scanning electron microscopy (SEM). The developed electrode showed higher electrocatalytic properties towards the detection of dopamine (DA) in 0.1 M phosphate buffer solution (PBS) at pH 7.0. The effect of pH, scan rate, accumulation time and concentration of dopamine was studied at poly(SR)/CPE. The poly(SR)/CPE was successfully used as a sensor for the selective determination of DA in presence of ascorbic acid (AA) and uric acid (UA) without any interference. The poly(SR)/CPE showed a good detection limit of 0.7 μM over the linear dynamic range of 1.6 μM to 16 μM, which is extremely lower than the reported methods. The prepared poly(SR)/CPE exhibited good stability, high sensitivity, better reproducibility, low detection limit towards the determination of DA. The developed method was also applied for the determination of DA in real samples. - Highlights: • Electropolymerization of spands reagent was fabricated by cyclic voltammetry • The Poly (spands reagent) electrode shows excellent electrocatalytic activity for the detection of dopamine. • The detection limit for dopamine was found to be 0.7 μM. • The proposed method can be applied for DA in injection and human blood serum samples.

  20. Lysine requirements of pre-lay broiler breeder pullets: determination by indicator amino acid oxidation.

    Science.gov (United States)

    Coleman, Russell A; Bertolo, Robert F; Moehn, Soenke; Leslie, Michael A; Ball, Ronald O; Korver, Doug R

    2003-09-01

    The indicator amino acid oxidation (IAAO) method allows the determination of amino acid requirements under conditions of low growth rate as found in pre-laying broiler breeder pullets. Cobb 500 breeder pullets (20 wk old; 2290 +/- 280 g, n = 4) were adapted (6 d) to a pelleted, purified control diet containing all nutrients at >or=110% of NRC recommendations. After recovery from surgery for implantation of a jugular catheter, each bird was fed, in random order, test diets containing one of nine levels of lysine (0.48, 0.96, 1.92, 2.88, 3.84, 4.80, 7.68, 9.60 and 14.40 g/kg of diet). Indicator oxidation was determined during 4-h primed (74 kBq/kg body), constant infusions (44 kBq x h(-1). kg body(-1)) of L-[1-(14)C]phenylalanine. Using the breakpoint of a one-slope broken-line model, the lysine requirement was determined to be 4.88 +/- 0.96 g/kg of diet or 366 +/- 72 mg x hen(-1) x d(-1) with an upper 95% CI of 6.40 g/kg of diet or 480 mg x hen(-1) x d(-1). IAAO allows determination of individual bird amino acid requirements for specific ages and types of birds over short periods of time and enables more accurate broiler breeder pullet diet formulation.

  1. Alternative method for impurities content determination in Al{sub 2}O{sub 3}-B{sub 4}C; Metodo alternativo para a determinacao de alguns contaminantes em Al{sub 2}O{sub 3}-B{sub 4}C

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Ieda S.; Gennari, Roseli F. [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), SP (Brazil). Lab. de Caracterizacao Quimica

    2000-07-01

    The compound AL{sub 2} O{sub 3}-B{sub 4} C is used in PWR reactors (Pressurized Water Reactor) as burn poison. Its function is to control the reaction rate in nucleus during reactor operation. The boron is the dispersed neutrons absorption material in alumina matrix. Once the poisons burn are fundamental for a regular, safety and constant operation, in the PWR reactor cycle beginning, the impurities content must be accurately controlled. The ASTM norm C809 states as standard methodology, for impurity determination, the direct current arc optical emission spectrometry. In this work, a comparative study for chromium, iron, nickel and silicon determination was made. The studied samples were Al{sub 2} O{sub 3} (in the power or in sintered pellets form) and Al{sub 2} O{sub 3}-B{sub 4} C (in sintered pellet form), and using two instrumental techniques: Direct Current Arc Optical Emission Spectrometry (DCArc-OES) and X-rays Fluorescence Spectrometry (XRF), looking for one alternative methodology for some impurities determination. With the obtained results it was possible to conclude that XRF can be used as alternative methodology for Cr, Fe, Ni and Si determination in Al{sub 2} O{sub 3} and/or Al{sub 2} O{sub 3}-B{sub 4} C samples. (author)

  2. Recent developments in fatty acids profile determination in biological samples - a review

    Directory of Open Access Journals (Sweden)

    Tiuca Ioana

    2015-12-01

    Full Text Available The present paper is a literature review of the recent years dealing with the most important separation techniques of fatty acids in biological samples. Our aim was to make a synthesis of the analytical methods used, to note the most used ones, but also to mention other methods that are less utilized, which can have important advantages (such as less time consuming, greener reagents, etc.. Gas-chromatographic separation methods were described and compared to liquid chromatographic separations of fatty acids in different types of biological samples. In the same time, the importance of determining fatty acids profiles in biological samples was revealed, pointing out the possible implications in diagnostics of different types of disorders or remarking different profiles compared to healthy states.

  3. Electrochemical Oxidation and Determination of Oxalic Acid at an Exfoliated Graphite-Polystyrene Composite Electrode

    Directory of Open Access Journals (Sweden)

    Joop Schoonman

    2007-04-01

    Full Text Available An exfoliated graphite-polystyrene composite electrode was evaluated as analternative electrode in the oxidation and the determination of oxalic acid in 0.1 M Na2SO4supporting electrolyte. Using CV, LSV, CA procedures, linear dependences I vs. C wereobtained in the concentrations range of oxalic acid between 0.5 to 3 mM, with LOD =0.05mM, and recovery degree of 98%, without need of surface renewing between successiveruns. The accuracy of the methods was evaluated as excellent comparing the detection resultswith that obtained using conventional KMnO4 titration method. In addition, the apparentdiffusion coefficient of oxalic acid D was found to be around 2.89 · 10-8 cm2·s-1 by CA andCV.

  4. [Determination of acidity and vitamin C in apples using portable NIR analyzer].

    Science.gov (United States)

    Yang, Fan; Li, Ya-Ting; Gu, Xuan; Ma, Jiang; Fan, Xing; Wang, Xiao-Xuan; Zhang, Zhuo-Yong

    2011-09-01

    Near infrared (NIR) spectroscopy technology based on a portable NIR analyzer, combined with kernel Isomap algorithm and generalized regression neural network (GRNN) has been applied to establishing quantitative models for prediction of acidity and vitamin C in six kinds of apple samples. The obtained results demonstrated that the fitting and the predictive accuracy of the models with kernel Isomap algorithm were satisfactory. The correlation between actual and predicted values of calibration samples (R(c)) obtained by the acidity model was 0.999 4, and for prediction samples (R(p)) was 0.979 9. The root mean square error of prediction set (RMSEP) was 0.055 8. For the vitamin C model, R(c) was 0.989 1, R(p) was 0.927 2, and RMSEP was 4.043 1. Results proved that the portable NIR analyzer can be a feasible tool for the determination of acidity and vitamin C in apples.

  5. Determination of uric acid in human urine by ion chromatography with conductivity detector

    Institute of Scientific and Technical Information of China (English)

    Fu Yong Zhao; Zong Hua Wang; Hui Wang; Rui Zhao; Ming Yu Ding

    2011-01-01

    A simple, fast, precise and eco-friendly analytical method for the determination of uric acid (UA) in human urine by ion chromatography (IC) was established. The sample pretreatment was not required, only needed centrifugation and filtration. The separation was carried out on a cation exchange column with 2.0 mmol/L nitric acid as mobile phase at the flow-rate 1.0 mL/min. A non-suppressed conductivity detector was used. The IC analysis time for one run was within 10 min under the optimized IC condition. The detection limits were 0.5 μg/L(S/N = 3) for uric acid. The recovery was 100.1 % while the relative standard deviation (RSD) was 1.8% from 10 measurements.

  6. Voltammetric determination of carbidopa and folic acid using a modified carbon nanotubes paste electrode

    Directory of Open Access Journals (Sweden)

    Keshtkar Nasrin

    2015-01-01

    Full Text Available A novel electrochemical sensor for the selective and sensitive detection of carbidopa in presence of large excess of folic acid at physiological pH was developed by the bulk modification of carbon paste electrode (CPE with carbon nanotubes (CNTs and vinylferrocene. Large peak separation, good sensitivity and stability allow this modified electrode to analyze carbidopa individually and simultaneously along with folic acid. Applying square wave voltammetry (SWV, a linear dynamic range of 1.0×10-6- 7.0×10-4 M with detection limit of 2.0×10-7 M was obtained for carbidopa. Finally, the proposed method was applied to the determination of carbidopa and folic acid in urine sample.

  7. Interference from alpha-amino acid and protein on determination of formaldehyde in food

    Science.gov (United States)

    Lu, Xiumin; Zhang, Xiaofeng; Fu, Yujie; Xiang, Jinxin

    2005-12-01

    The disturbance of alpha-amino acids and proteins on the analysis of formaldehyde content in food was investigated by electrochemical assay. Results show that the pH decreases gradually from 9.91 to 4.36 with increasing aspartic acid concentration. The recovery rate changes from 8% to 100% after different amounts of formaldehyde were added into protein solutions. For edible bamboo shoots, the recovery rate of formaldehyde is 80% to 100%. For shrimp kernel, however, the recovery rate of formaldehyde is 8% to 60%. These results indicate that the consumed quantity of formaldehyde is correlative with the protein concentration in foods. Therefore, the determinate formaldehyde content in food is actually not the totally applied amount, but just the residue after its reaction with the alpha-amino acids or free amino groups on the protein surface.

  8. Simultaneous Determination of Trigonelline, Caffeine, Chlorogenic Acid and Their Related Compounds in Instant Coffee Samples by HPLC Using an Acidic Mobile Phase Containing Octanesulfonate.

    Science.gov (United States)

    Arai, Kana; Terashima, Hiroyuki; Aizawa, Sen-ichi; Taga, Atsushi; Yamamoto, Atsushi; Tsutsumiuchi, Kaname; Kodama, Shuji

    2015-01-01

    In order to analyze trigonelline, caffeine, chlorogenic acid, and their related compounds simultaneously, an HPLC method using an InertSustain C18 column and a mobile phase containing octanesulfonate as an ion-pairing reagent under an acidic condition was developed. The optimum mobile phase conditions were determined to be 0.1% phosphoric acid, 4 mM octanesulfonate, and 15% methanol at 35°C. Using the proposed method, trigonelline, nicotinic acid, caffeine, theophylline, chlorogenic acid, and caffeic acid in ten instant coffee samples were analyzed. These analytes except for theophylline were detected in all samples. An increase in the caffeine content in instant coffee samples tended to decrease in both trigonelline and chlorogenic acid contents, and the trigonelline content was found to be correlated well with the chlorogenic acid content (R(2) = 0.887).

  9. Determination of tenuazonic acid in human urine by means of a stable isotope dilution assay.

    Science.gov (United States)

    Asam, Stefan; Habler, Katharina; Rychlik, Michael

    2013-05-01

    The content of tenuazonic acid in human urine was determined by a stable isotope dilution assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02-100. The limits of detection and determination were 0.2 and 0.6 μg/L, respectively. The mean recovery of the stable isotope dilution assay was 102 ± 3 % in the range between 1.0 and 100 μg/L. Interassay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of tenuazonic acid: In the first study, tenuazonic acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3-17.3 μg/L or 2.3-10.3 ng/mg(-1) creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 μg tenuazonic acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested tenuazonic acid was 54-81 % after 6 h, depending on matrix and volunteer. After 24 h, 87-93 % of the ingested amount of tenuazonic acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.

  10. A Modified Amino Acid Analysis Using PITC Derivatization for Soybeans with Accurate Determination of Cysteine and Half-Cystine

    Science.gov (United States)

    Breeding efforts to change amino acid profile of seed protein and the assessment of genetic variation for amino acid composition among soybean germplasm resources have been hampered by lack of a rapid and inexpensive method for amino acid determination. A modified procedure presented here is based p...

  11. Response to the Letter to the Editor regarding "Determination of the fatty acid profile by 1H-NMR spectroscopy."

    Science.gov (United States)

    In expansion of previous work (G. Knothe, J.A. Kenar, Determination of the fatty acid profile by 1H-NMR spectroscopy, Eur. J. Lipid Sci. Technol. 2004, 106, 88-96), an additional approach is discussed for quantitating saturated fatty acids in the fatty acid profiles of common vegetable oils by 1H-NM...

  12. Spectrophotometric determination of the acidity constants of calcon in water and mixed water–organic solvents

    Directory of Open Access Journals (Sweden)

    MOHAMMAD MAZLOUM-ARDAKANI

    2009-02-01

    Full Text Available The acid–base properties of calcon (1-(2-hydroxy-1-naphthylazo-2-naphthol-4-sulfonic acid in water and mixed water–organic solvents at 25 °C at an ionic strength of 0.10 M are studied by a multiwavelength spectrophotometric method. The organic solvents used were the amphiprotic (methanol, dipolar aprotic (dimethylsulfoxide, and low basic aprotic (acetonitrile. To evaluate the pH absorbance data, a resolution method based on the combination of soft- and hard-modeling was applied. The acidity constants of all related equilibria were estimated using the whole spectral fitting of the collected data to an established factor analysis model. The data analysis program Datan was applied for determination of the acidity constants. The corresponding pKa values were determined in water and mixed water–organic solvents. Linear relationship between the acidity constants and the mole fraction of the different sol-vents in the mixtures exist. The effect of solvent properties on acid–base behavior is discussed.

  13. Coulometric-potentiometric determination of autoprotolysis constant and relative acidity scale of water

    Directory of Open Access Journals (Sweden)

    Džudović Radmila M.

    2010-01-01

    Full Text Available The autoprotolysis constant and relative acidity scale of water were determined by applying the coulometric-potentiometric method and a hydrogen/palladium (H2/Pd generator anode. In the described procedure for the evaluation of autoprotolysis constant, a strong base generated coulometrically at the platinum cathode in situ in the electrolytic cell, in presence of sodium perchlorate as the supporting electrolyte, is titrated with hydrogen ions obtained by the anodic oxidation of hydrogen dissolved in palladium electrode. The titration was carried out with a glass-SCE electrode pair at 25.0±0.1°C. The value obtained pKw = 13.91 ± 0.06 is in agreement with literature data. The range of acidity scale of water is determined from the difference between the halfneutralization potentials of electrogenerated perchloric acid and that of sodium hydroxide in a sodium perchlorate medium. The halfneutralization potentials were measured using both a glass-SCE and a (H2/Pdind-SCE electrode pairs. A wider range of relative acidity scale of water was obtained with the glass-SCE electrode pair.

  14. Compositional characteristics of commercial yoghurt based on quantitative determination of viable lactic acid bacteria

    Directory of Open Access Journals (Sweden)

    Niketić Gordana B.

    2009-01-01

    Full Text Available Yoghurt quality is particularly difficult to standardize because of the many forms, varieties, manufacturing methods, ingredients and consumer preferences that exist. Since these factors will always play an important role, it is unlikely that a uniform yoghurt quality concept will ever emerge, such as has been developed for other dairy products. There are a number of common denominators, however that have bearing on yoghurt quality. Since a number of producers are recognized within the broad category entitled yoghurt. This situation makes yoghurt an interesting, challenging, but also a confusing area to work in. The present investigation was undertaken to isolate from commercial yoghurt the strains involved in its manufacture and determine the characteristics of Streptococcus thermophilus and Lactobacillus delbrueckii subsp.bulgaricus. This study is concerned with the lactic acid bacteria (L.delbrueckii subsp. bulgaricus and S. thermophilus growth in yoghurt from involving different procedures and with the determination of the number of lactic acid bacteria in dependence of the temperature and acidity in the period of storage. Predominant samples of yoghurt were with 11-107/ml lactic acid lactococci (44.28%.

  15. HPLC/DAD determination of rosmarinic acid in Salvia officinalis: sample preparation optimization by factorial design

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Karina B. de [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Farmacia; Oliveira, Bras H. de, E-mail: bho@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Quimica

    2013-01-15

    Sage (Salvia officinalis) contains high amounts of the biologically active rosmarinic acid (RA) and other polyphenolic compounds. RA is easily oxidized, and may undergo degradation during sample preparation for analysis. The objective of this work was to develop and validate an analytical procedure for determination of RA in sage, using factorial design of experiments for optimizing sample preparation. The statistically significant variables for improving RA extraction yield were determined initially and then used in the optimization step, using central composite design (CCD). The analytical method was then fully validated, and used for the analysis of commercial samples of sage. The optimized procedure involved extraction with aqueous methanol (40%) containing an antioxidant mixture (ascorbic acid and ethylenediaminetetraacetic acid (EDTA)), with sonication at 45 deg C for 20 min. The samples were then injected in a system containing a C{sub 18} column, using methanol (A) and 0.1% phosphoric acid in water (B) in step gradient mode (45A:55B, 0-5 min; 80A:20B, 5-10 min) with flow rate of 1.0 mL min-1 and detection at 330 nm. Using this conditions, RA concentrations were 50% higher when compared to extractions without antioxidants (98.94 {+-} 1.07% recovery). Auto-oxidation of RA during sample extraction was prevented by the use of antioxidants resulting in more reliable analytical results. The method was then used for the analysis of commercial samples of sage. (author)

  16. DETERMINATION OF AMINO ACIDS IN TWO POLYSIPHONIA SPECIES AND STUDY OF ENZYMATIC HYDROLYSIS METHOD

    Institute of Scientific and Technical Information of China (English)

    张立新; 范晓; 魏玉西

    2002-01-01

    The total content ot the nch amino acids in two common red algae, Potystpnoma urceolata and Polysiphonia japonica growing in the Qingdao seashore were determined. The algae powder was hydrolyzed by 6 mol/L HC1 at 110℃ for 48 h and determined by amino acid analyzer. The content was 25.35% and 24.16% , respectively, much higher than that of some other species. In addition, a nutritive liquid with abundant amino acids was prepared (by the enzymatic hydrolysis method using Polysiphonia urceolata ) as raw material for a kind of health beverage. The dried seaweed was decolored by 0.25% KMnO4 and 0.5% active carbon, then enzymalized. In the selection of enzymalizing condition, the orthogonal experimental design was used. Four factors including kinds of enzyme, quantity of enzyme, temperature and time were studied at 3 levels. According to the orthogonal design results, we can choose an optimal condition: hydrolyzing at 45℃ by neutral proteinase (0.25% , w/w) for 2 h, adjusting pH to 8.5, then adding trypsin (0.25% , w/w) and hydrolyzing for 2 h. Finally the above solution was alkalized by NaOH and neutralized by casein. After the hydrolyzed liquid was filtered and concentrated, suitable additives were added. The final products contain rich amino acids.

  17. Application of a method for the determination of yeast cell density to studies on the sedimentation of Saccharomyces cerevisiae in alcoholic fermentation broths; Aplicacao de metodo para a determinacao da densidade de celulas de leveduras a estudos sobre sedimentacao de Aaccharomyces cerecisiae em mostos de fermentacao alcoolica

    Energy Technology Data Exchange (ETDEWEB)

    Maia, Amazile B.R.A. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Escola de Engenharia. Dept. de Engenharia Quimica; Nelson, David Lee [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Faculdade de Farmacia. Dept. de Alimentos

    1993-09-01

    A technique that permitted the determination of the Saccharomyces cerevisiae cell density was developed. The average results (1,04 g/ml) attributed to the cells under the conditions of the effected tests, was applied to a previously developed mathematical model for predicting the clarification velocity of alcoholic fermentation broths in a sedimenter prototype designed for accelerating the sedimentation of cells. (author) 19 refs., 1 fig., 4 tabs.

  18. Determination of the transient parameters of synchronous machines by the finite element method considering the characteristic effect in the shock absorber buses; Determinacao dos parametros transitorios de maquinas sincronas pelo metodo dos elementos finitos considerando o efeito pelicular nas barras amortecedoras

    Energy Technology Data Exchange (ETDEWEB)

    Nabeta, Silvio Ikuyo; Cardoso, Jose Roberto [Sao Paulo Univ., SP (Brazil). Escola Politecnica; Foggia, Albert; Coulomb, Jean Louis; Reyne, Gilbert [Institut National Polytechnique, 38 - Grenoble (France)

    1995-12-31

    This work presents the determination of the parameters of a hydro generator through the simulation of the frequency response test. The special characteristic of this work is that it takes into consideration shock absorbers buses, which are sites of induced currents when the peculiar effect is present and require that sub-transients parameters are analysed. Simulation results are analysed and compared to the obtained values when the traditional three-phase short circuit test is used 8 figs., 2 tabs., 13 refs.

  19. Simultaneous determination of betulin and betulinic acid in white birch bark using RP-HPLC.

    Science.gov (United States)

    Zhao, Guoling; Yan, Weidong; Cao, Dan

    2007-02-19

    A simple procedure is described for the simultaneous extraction and determination of betulin and betulinic acid in white birch bark. The extraction was checked using different solvents: dichloromethane, ethyl acetate, acetone, chloroform, methanol and 95% ethanol (aqueous solution, v/v). It was found 95% ethanol was a good extraction solvent that allowed extraction of triterpenoid with a highest content. Separation was achieved on a reversed phase C(18) column with acetonitrile-water 86:14 (v/v). Detection was accomplished with UV detection at lambda=210 nm. Using this method, the bioactive triterpenoid in white birch bark were simultaneously determined. Significant variations in the content of betulin and betulinic acid in white birch bark growing in different locations of China were also observed.

  20. Glycosyltransferases A and B: Four Critical Amino Acids Determine Blood Type

    Science.gov (United States)

    Rose, Natisha L.; Palcic, Monica M.; Evans, Stephen V.

    2005-12-01

    Human A, B, and O blood type is determined by the presence or absence of distinct carbohydrate structures on red blood cells. Type O individuals have α-fucose(1→2)galactose disaccharides [O(H) structures] on their cell surfaces while in type A or B individuals, the O antigen is capped by the addition of an α- N -acetylgalactosamine or α-galactose residue, respectively. The addition of these monosaccharides is catalyzed by glycosyltransferase A (GTA) or glycosyltransferase B (GTB). These are homologous enzymes differing by only 4 amino acids out of 354 that change the specificity from GTA to GTB. In this review the chemistry of the blood group ABO system and the role of GTA, GTB, and the four critical amino acids in determining blood group status are discussed. See JCE Featured Molecules .

  1. Determination of Precipitation Limit of Zn(II Ion with (2S-2-Aminobutanedioic Acid

    Directory of Open Access Journals (Sweden)

    Fatmir Faiku

    2009-01-01

    Full Text Available Problem statement: In this study we examined the precipitation of Zn(II ion in water solutions of ZnSO4.7H2O (1.10-2 and 5.10-3 mol L-1 with (2S-2-aminobutanedioic acid (1.10--1.10-3 mol L-1 in constant ionic strength of 0.6 mol L-1 NaCl. We have determined the concentration region where we have found the clear solution and solid phase. The solid phase is analyzed by IR spectroscopy. Approach: From precipitation diagrams of zinc with (2S-2-aminobutanedioic acid in ionic force 0.6 mol L-1 NaCl, we have found that during decreasing the concentration (2S-2-aminobutanedioic acid in case of constant concentration of Zn(II the limit of precipitation is shifted to lower values of pH. Results: Also from precipitation diagrams we can see that when the concentration of zinc increases, in case of constant concentration of (2S-2-aminobutanedioic acid the limit of precipitation will shift at lower values of pH. Conclusion: From the IR spectroscopic analysis we can conclude that Zn (II ion has reacted with (2S-2-aminobutanedioic acid.

  2. Simultaneous determination of acidic pesticides in vegetables and fruits by liquid chromatography--tandem mass spectrometry.

    Science.gov (United States)

    Shida, Shizuka S; Nemoto, Satoru; Matsuda, Rieko

    2015-01-01

    A sensitive and efficient method has been developed for the simultaneous determination of 73 multi-class acidic pesticides, such as phenoxy acid and sulfonylurea herbicides, in vegetables and fruits. The sample preparation procedure was carefully optimized for the efficient removal of co-extracted matrix components. The method involves extraction of acidic pesticides with acetonitrile containing hydrochloric acid, removal of water from crude extract by salting out, and sequential cleanup by octadecylsilyl silica gel and silica gel columns. For samples containing high amounts of pigments, such as spinach, additional cleanup using a graphitized carbon column was performed prior to liquid chromatography-mass spectrometry (LC-MS/MS) analysis. Recovery tests were performed for five times for each sample of cabbage, spinach, potato, eggplant, orange, and apple fortified at 0.01 mg kg-1. Out of the 73 tested pesticides, 70 for cabbage, 67 for spinach, 69 for potato, 67 for eggplant, 64 for orange, and 70 for apple were within the range of 70-120%, with relative standard deviations below 25%. Nitenpyram and pyrasulfotole showed low recoveries for all the samples tested, probably due to low recoveries from silica gel column. The developed method effectively removed co-extracted matrix components and was highly selective, with no interfering peaks found in the chromatograms of blank samples. The overall results indicate that the developed method is suitable for the quantitative analysis of acidic pesticide residues in vegetables and fruits.

  3. Microwave-Assisted Synthesis of (±-Mandelic Acid-d5, Optical Resolution, and Absolute Configuration Determination

    Directory of Open Access Journals (Sweden)

    Claudio Bruno

    2013-01-01

    Full Text Available An efficient microwave-assisted synthesis of (±-mandelic acid-d5 was developed. The racemic mixture was resolved by diastereomeric salt formation using 1-phenylethylamine enantiomers as resolving agents. At each step, the resolution process was checked by determining mandelic acid-d5 enantiomer ee values directly on fractional crystallized diastereomeric salts by chiral capillary electrophoresis analysis. Highly enriched (−- and (+-mandelic acid-d5 (95% and 90% ee, resp. were obtained and their absolute configurations—R and S, respectively—were determined by correlation of the (−-mandelic acid-d5 circular dichroism spectrum to the (R-mandelic acid one.

  4. Determination of free fatty acids in pharmaceutical lipids by ¹H NMR and comparison with the classical acid value.

    Science.gov (United States)

    Skiera, Christina; Steliopoulos, Panagiotis; Kuballa, Thomas; Diehl, Bernd; Holzgrabe, Ulrike

    2014-05-01

    Indices like acid value, peroxide value, and saponification value play an important role in quality control and identification of lipids. Requirements on these parameters are given by the monographs of the European pharmacopeia. (1)H NMR spectroscopy provides a fast and simple alternative to these classical approaches. In the present work a new (1)H NMR approach to determine the acid value is described. The method was validated using a statistical approach based on a variance components model. The performance under repeatability and in-house reproducibility conditions was assessed. We applied this (1)H NMR assay to a wide range of different fatty oils. A total of 305 oil and fat samples were examined by both the classical and the NMR method. Except for hard fat, the data obtained by the two methods were in good agreement. The (1)H NMR method was adapted to analyse waxes and oleyloleat. Furthermore, the effect of solvent and in the case of castor oil the effect of the oil matrix on line broadening and chemical shift of the carboxyl group signal are discussed.

  5. Morphology-dependent Electrochemical Enhancements of Porous Carbon as Sensitive Determination Platform for Ascorbic Acid, Dopamine and Uric Acid

    Science.gov (United States)

    Cheng, Qin; Ji, Liudi; Wu, Kangbing; Zhang, Weikang

    2016-02-01

    Using starch as the carbon precursor and different-sized ZnO naoparticles as the hard template, a series of porous carbon materials for electrochemical sensing were prepared. Experiments of scanning electron microscopy, transmission electron microscopy and Nitrogen adsorption-desorption isotherms reveal that the particle size of ZnO has big impacts on the porous morphology and surface area of the resulting carbon materials. Through ultrasonic dispersion of porous carbon and subsequent solvent evaporation, different sensing interfaces were constructed on the surface of glassy carbon electrode (GCE). The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) were studied. On the surface of porous carbon materials, the accumulation efficiency and electron transfer ability of AA, DA and UA are improved, and consequently their oxidation signals enhance greatly. Moreover, the interface enhancement effects of porous carbon are also controlled by the particle size of hard template. The constructed porous carbon interface displays strong signal amplification ability and holds great promise in constructing a sensitive platform for the simultaneous determination of AA, DA and UA.

  6. Determination of oleanolic acid, ursolic acid and amygdalin in the flower of Eriobotrya japonica Lindl. by HPLC.

    Science.gov (United States)

    Zhou, Chunhua; Chen, Kunsong; Sun, Chongde; Chen, Qingjun; Zhang, Wangshu; Li, Xian

    2007-07-01

    Simple and accurate HPLC methods were developed for the determination of oleanolic acid (OA), ursolic acid (UA) and amygdalin in loquat (Eriobotrya japonica Lindl.) flower, which is commonly used for the treatment of various diseases as a traditional Chinese medicine. HPLC assay was performed on a reversed-phase C(18) column and all three compounds were detected at 210 nm with a flow rate of 1.0 mL/min. The mobile phase consisted of methanol (A) and 0.03 mol/L phosphate buffer (pH 2.8) (B) with a ratio of 88:12 (A:B, v/v) for simultaneous detection of OA and UA, and 25:75 (A:B, v/v) for detection of amygdalin. The established methods showed good precision and accuracy with overall intra-day and inter-day variation of 0.99-3.55 and 1.05-4.05%, respectively, and overall recoveries of 97.37-99.32% for the three compounds. Application of these methods to determine the OA, UA and amygdalin contents in loquat flower showed that cultivar had a minor effect on the contents of all three compounds, with average amounts of 0.38-0.51 mg OA/g dry weight (DW), 2.15-2.68 mg UA/g DW and 1.23-1.56 mg amygdalin/g DW among five loquat cultivars tested. However, developmental stages and flower tissues showed significant effect on the contents of all three bioactive components.

  7. Determination of the mean solid-liquid interface energy of pivalic acid

    Science.gov (United States)

    Singh, N. B.; Gliksman, M. E.

    1989-01-01

    A high-confidence solid-liquid interfacial energy is determined for an anisotropic material. A coaxial composite having a cylindrical specimen chamber geometry provides a thermal gradient with an axial heating wire. The surface energy is derived from measurements of grain boundary groove shapes. Applying this method to pivalic acid, a surface energy of 2.84 erg/sq cm was determined with a total systematic and random error less than 10 percent. The value of interfacial energy corresponds to 24 percent of the latent heat of fusion per molecule.

  8. Determination of uranium isotopes in environmental samples by anion exchange in sulfuric and hydrochloric acid media.

    Science.gov (United States)

    Popov, L

    2016-09-01

    Method for determination of uranium isotopes in various environmental samples is presented. The major advantages of the method are the low cost of the analysis, high radiochemical yields and good decontamination factors from the matrix elements, natural and man-made radionuclides. The separation and purification of uranium is attained by adsorption with strong base anion exchange resin in sulfuric and hydrochloric acid media. Uranium is electrodeposited on a stainless steel disk and measured by alpha spectrometry. The analytical method has been applied for the determination of concentrations of uranium isotopes in mineral, spring and tap waters from Bulgaria. The analytical quality was checked by analyzing reference materials.

  9. Catalytic Kinetic Determination of Micro Amounts of Oxalic Acid by Second-Order Derivative Oscillopolarography

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    It was found that micro amounts of oxalate showed a very strong catalytic effect on the slow reaction between K2Cr2O7 and Orange Ⅳ in a diluted sulfuric acid medium in a water bath at 70 ℃. Orange Ⅳ exhibited a sensitive second-order derivative polarographic wave at -0.50 V(vs. SCE). This provides the basis for a sensitive and selective catalytic kinetic method for oxalate determination with second-order derivative oscillopolarography. The effects of sulphuric acid, K2Cr2O7, and orange Ⅳ concentrations, reaction temperature and reaction time were investigated. A calibration curve of oxalate in the range of 0.1—2.0 μg/mL was obtained by the fixed-time procedure. The detection limit was 0.03 μg/ mL. The possible interference from co-existing substances or ions was examined. The new method has a high sensitivity and a good selectivity compared to other existing methods for oxalic acid determination. It has been applied to the determination of micro amounts of oxalate in real urine samples with satisfactory results.

  10. Determination of ingestion levels of arsenic, antimony, cadmium, thorium and uranium in children diets by duplicate portion method; Determinacao dos niveis de ingestao dietetica dos elementos arsenio, antimonio, cadmio, torio, tungstenio e uranio em dietas de criancas pelo metodo da porcao em duplicata

    Energy Technology Data Exchange (ETDEWEB)

    Maihara, Vera T.; Vasconcellos, Marina B.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Supervisao de Radioquimica

    1996-07-01

    A study was made with a group of 19 pre-school children at the central nursery of the University of Sao Paulo with the aim of evaluating the toxic elements contents present in diets of this group. The diet samples were collected by duplicate portion method. A radiochemical was applied to the determination of Cd, Sb, Th, U and W by means of retention of these elements in the chelating resin Chelex 100, in 0,1 M H Ac-NH{sub 4}Ac medium, followed by retention of As in the inorganic exchanger tin dioxide, in HCl 6 M medium. (author)

  11. Study of an X-ray fluorescence thin film method for the determination of uranium in low activity solutions; Estudio de un metodo de fluorescencia de rayos X en capa delgada para la determinacion del uranio en soluciones de baja actividad

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Guerra, J. P.

    1980-07-01

    The application of the X-ray fluorescence thin film technique to the uranium determination in nitric solutions for a concentration range from 1 g/l to 100 g/l and activity levels under 5 mCi/ml is studied. The most suited excitation and measurement conditions are also studied and the uranium matrix effect correction, which is performed through the double dilution, {alpha}{sub U}U interaction coefficient calculation and internal standard methods, is discussed. The specimen preparation is satisfactorily accomplished by using P.V.C. filters fixed on aluminium supports. (Author) 18 refs.

  12. Optimization of the Analytical Method Using HPLC with Fluorescence Detection to Determine Selected Polycyclic Aromatic Compounds in Clean Water Samples; Optimizacion del Metodo Analitico mediante HPLC con Detector de Fluorescencia para la Determinacion de Ciertos Compuestos Aromaticos Policiclicos en Muestras de Aguas Limpias

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Alonso, S.; Perez Pastor, R. M.

    2013-10-01

    A study on the comparison and evaluation of 3 miniaturized extraction methods for the determination of selected PACs in clear waters is presented. Three types of liquid-liquid extraction were used for chromatographic analysis by HPLC with fluorescence detection. The main objective was the optimization and development of simple, rapid and low cost methods, minimizing the use of extracting solvent volume. The work also includes a study on the scope of the methods developed at low and high levels of concentration and intermediate precision. (Author)

  13. Determination of the ratio of the spectral fluence of electrons in water, using a Newton Cotes closed quadrature method: rule composed of trapezium with non equi-spaced nodes; Determinacion de la razon de fluencias espectrales de electrones en agua, usando un metodo de cuadratura cerrada de Newton Cotes: regla compuesta del trapecio con nodos no equi-espaciados

    Energy Technology Data Exchange (ETDEWEB)

    Moranchel y Rodriguez, M. [IPN, ESFM, Departamento de Ingenieria Nuclear, 07738 Mexico D.F. (Mexico)]. e-mail: mmoranchel@ipn.mx

    2008-07-01

    The central problem of the dosimetry of the ionizing radiations is the determination of the dissipated energy by unit of mass of irradiated material. This energy usually is inferred of ionization measures in a small cavity of air housed inside the material medium. The Bragg-Gray cavity theory was the first one in estimating the dissipated energy through the ionizations that the primary electrons cause in the cavity. The primary electrons are generated by photoelectric effect, pair production and by Compton dispersion of the photon beams that initially impact on the material. However, in a more realist approach the existence of secondary electrons due to the electron-electron interaction it will be considered. The Spencer-Attix cavity theory considers to the secondary electrons as responsible part for the energy deposited in the means, for that a total spectral fluence of electrons (primary and secondary) it appears in this theory. Few electrons spectra have been published, mainly, those that include the contribution of secondary electrons ({delta} rays). Leaving of the ideas of Spencer-Attix, in this work an approach method to determine the rate of electron spectral fluences (total regarding primary) for a wide variety of material Z, and energy sources T{sub 0} is presented. The method for materials used by Spencer-Attix is applied, it is proven its reliability and it is applied to the water like absorber medium by its importance in the clinical dosimetry. (Author)

  14. Implantation of gravimetric method for O/U ratio determination in fuel pellets of U O{sub 2}, at Centro de Desenvolvimento da Tecnologia Nuclear (CDTN); Implantacao no CDTN de metodo gravimetrico para determinacao de relacao O/U em pastilhas combustiveis de UO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, R.A.N.; Assis, G. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    1997-12-01

    The gravimetric methodology used by the Kraftwerk Union/Erlangen U O{sub 2} Laboratory is presented. This methodology was absorbed, transferred and implanted at the CDTN Materials and Nuclear Fuel Supervision. The method consist in oxide fuel pellets to U{sub 3} O{sub 8} in a platinum crucible. The crucible is previously dried at 800{sup 0} C during one hour and cooler in a desiccator under vacuum to avoid humidity adsorption, and then weighted. Fuel pellets pieces are put in the crucible, which is again weighted to determine the U O{sub 2} mass. The oxidation is performed in a muffle furnace at 470{sup 0} C during two hours and after dwell time the temperature is increased to 900{sup 0} C and maintained during two hours. The crucible is then removed and placed to cool down in the desiccator and weighted. From mass increasing, the O/U ratio of the sample is calculated. This methodology is routinely utilized in the fuel pellets quality control at CDTN, and was used to determine the stoichiometry of fuel pellets for irradiation tests. In this paper the methodology is presented as well as the experimental results obtained in these fuel pellets. (author). 1 ref., 1 tab.

  15. Determination of {sup 60} Co by means of Neutron Activation Analysis in the sorption of Co in synthesized porous oxides by the combustion method; Determinacion de {sup 60} Co por medio de AAN en la sorcion de Co en oxidos porosos sintetizados por metodo de combustion

    Energy Technology Data Exchange (ETDEWEB)

    Lugo, V.; Bulbulian, S.; Urena, F. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: violelugo@yahoo.es

    2005-07-01

    Recently inorganic materials are investigating as sorbent of radioactive pollutants present in water. The inorganic oxides belong to this group of materials. A quick method exists for the obtaining of inorganic oxides, denominated combustion method that could be used to produce porous oxides successfully with good properties for the sorption of radioactive ions. In this investigation, iron oxides, magnesium and zinc were synthesized obtained by the combustion method, comparing them with those synthesized by the calcination method, using two different synthesis temperatures. The obtained solids were characterized by scanning electron microscopy (Sem), by X-ray diffraction (XRD) and by semiquantitative elemental analysis (EDS). After the characterization, the crystalline oxides synthesized by both methods, to temperature of 800 C, were evaluated as sorbents in the removal of Co{sup 2+} ions, through experiments in batch, and using neutron activation analysis, determining the sorption percentage, with this it was concluded that the magnesium oxide produced by combustion it is more effective in the removal of Co{sup 2+} ions than that synthesized by calcination. It was determined the surface area of the magnesium oxides, obtaining a surface area greater for the synthesized oxide by combustion method. (Author)

  16. Total Acid Value Titration of Hydrotreated Biomass Fast Pyrolysis Oil: Determination of Carboxylic Acids and Phenolics with Multiple End-Point Detection

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, E.; Alleman, T. L.; McCormick, R. L.

    2013-01-01

    Total acid value titration has long been used to estimate corrosive potential of petroleum crude oil and fuel oil products. The method commonly used for this measurement, ASTM D664, utilizes KOH in isopropanol as the titrant with potentiometric end point determination by pH sensing electrode and Ag/AgCl reference electrode with LiCl electrolyte. A natural application of the D664 method is titration of pyrolysis-derived bio-oil, which is a candidate for refinery upgrading to produce drop in fuels. Determining the total acid value of pyrolysis derived bio-oil has proven challenging and not necessarily amenable to the methodology employed for petroleum products due to the different nature of acids present. We presented an acid value titration for bio-oil products in our previous publication which also utilizes potentiometry using tetrabutylammonium hydroxide in place of KOH as the titrant and tetraethylammonium bromide in place of LiCl as the reference electrolyte to improve the detection of these types of acids. This method was shown to detect numerous end points in samples of bio-oil that were not detected by D664. These end points were attributed to carboxylic acids and phenolics based on the results of HPLC and GC-MS studies. Additional work has led to refinement of the method and it has been established that both carboxylic acids and phenolics can be determined accurately. Use of pH buffer calibration to determine half-neutralization potentials of acids in conjunction with the analysis of model compounds has allowed us to conclude that this titration method is suitable for the determination of total acid value of pyrolysis oil and can be used to differentiate and quantify weak acid species. The measurement of phenolics in bio-oil is subject to a relatively high limit of detection, which may limit the utility of titrimetric methodology for characterizing the acidic potential of pyrolysis oil and products.

  17. Determination of Antioxidant, Anticholinesterase, Tyrosinase Inhibitory Activities and Fatty Acid Profiles of 10 Anatolian Klasea Cass. Species

    Directory of Open Access Journals (Sweden)

    Gülsen Tel

    2016-01-01

    Full Text Available In search of new natural fatty acid sources, extract of 10 different Turkish Klasea species were studies. Fatty acids of Klasea species were studied by GC and GC-MSD. Oleic acid (4.8-45.8%, palmitic acid (15.6-51.8%, linoleic acid (0.3-45.5%, palmitoleic acid (0.8-28.4% and linolenic acid (15.6-34.6% were the main fatty acids elucidated. All extracts were also subjected to acetylcholinesterase, butyrylcholinesterase, tyrosinase, β-carotene-linoleic acid, DPPH • scavenging, CUPRAC and ferrous ion-chelating ability activities. Total flavonoid and phenolic contents were determined as quercetin and pyrocatechol equivalents. All extracts showed significant antioxidant activity in all tests, except hexane extracts of K. serratuloides and K. cerinthifolia that showed weak inhibition against BChE and AChE. The hexane extract of K. coriaceae and methanol extract of K. serratuloides exhibited notable tyrosinase inhibitory activity.

  18. Comparison among physical and mathematical simulation methods to calibrate the scintillating detector to determine the high energy radionuclides in human body; Comparacao entre metodos de simulacao fisica e matematica para calibracao de detetor de cintilacao, visando a determinacao de radionuclideos de alta energia no corpo humano

    Energy Technology Data Exchange (ETDEWEB)

    Mello, J.Q.; Dantas, A.L.A.; Almeida, A.P.F.; Hunt, J.G.; Dantas, B.M., E-mail: jquince@bolsista.ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2015-07-01

    In vivo monitoring of photon emitters requires prior calibration of the detectors in order to obtain factors relate the count rate obtained in measuring the individual with this activity in the body. In this work were compared two calibration methods of a Nal scintillation detector (Tl) 3 x 3 for determination in vivo of {sup 40}K: (1) Experimental method using a physical-anthropomorphic simulator called BOMAB and (2) mathematical method using the VMC software (Visual Monte Carlo). Both methods aim at simulation of radionuclide distribution in the human body geometry and interaction of photons with the detector. The obtained results show the similarities and limitations of the evaluated methods for the measurement conditions used.

  19. Weak Acid Ionization Constants and the Determination of Weak Acid-Weak Base Reaction Equilibrium Constants in the General Chemistry Laboratory

    Science.gov (United States)

    Nyasulu, Frazier; McMills, Lauren; Barlag, Rebecca

    2013-01-01

    A laboratory to determine the equilibrium constants of weak acid negative weak base reactions is described. The equilibrium constants of component reactions when multiplied together equal the numerical value of the equilibrium constant of the summative reaction. The component reactions are weak acid ionization reactions, weak base hydrolysis…

  20. Determination of higher carboxylic acids in snow samples using solid-phase extraction and LC/MS-TOF.

    Science.gov (United States)

    Kippenberger, Matthias; Winterhalter, Richard; Moortgat, Geert K

    2008-12-01

    The objective of this work was to develop a method to determine the concentrations of higher organic acids in snow samples. The target species are the homologous aliphatic alpha,omega-dicarboxylic acids from C(5) to C(13), pinonic acid, pinic acid and phthalic acid. A preconcentration procedure utilizing solid phase extraction was developed and optimized using solutions of authentic standards. The influences of different parameters such as flow rate during extraction and the concentration of the eluent on the efficiency of the extraction procedure were investigated. The compounds of interest were separated by HPLC and detected by a quadrupole time-of-flight mass spectrometer (qTOF-MS). The recovery rate (extraction efficiency) of the extraction procedure was found to vary between 41% for tridecanedioic acid and 102% for adipic acid. The limits of detection were determined for all compounds and were between 0.9 nmol/L (dodecanedioic acid) and 29.5 nmol/L (pinonic acid). An exception is pinic acid, for which a considerably higher detection limit of 103.9 nmol/L was calculated. Snow samples were collected in December 2006 and January 2007 at the Fee glacier (Switzerland) from locations at heights from 3056 to 3580 m asl and from different depths within the snow layer. In total, the analysis of 61 single snow samples was performed, and the following compounds could be quantified: homologous aliphatic alpha,omega-dicarboxylic acids with 5-12 carbon atoms and phthalic acid. Tridecanedioic acid, pinonic and pinic acid were identified in the samples but were not quantified due to their low concentrations. The three most abundant acids found in the molten snow samples were glutaric acid (C(5)-di; 3.90 nmol/L), adipic acid (C(6)-di; 3.35 nmol/L) and phthalic acid (Ph; 3.04 nmol/L).

  1. Determination of some aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography with conductimetric detection on a weakly acidic cation-exchange resin column.

    Science.gov (United States)

    Ito, Kazuaki; Takayama, Yohichi; Ikedo, Mikaru; Mori, Masanobu; Taoda, Hiroshi; Xu, Qun; Hu, Wenzhi; Sunahara, Hiroshi; Hayashi, Tsuneo; Sato, Shinji; Hirokawa, Takeshi; Tanaka, Kazuhiko

    2004-06-11

    The determination of seven aliphatic carboxylic acids, formic, acetic, propionic, isobutyric, n-butyric, isovaleric and n-valeric acids in anaerobic digestion process waters was examined using ion-exclusion chromatography with conductimetric detection. The analysis of these biologically important carboxylic acids is necessary as a measure for evaluating and controlling the process. The ion-exclusion chromatography system employed consisted of polymethacrylate-based weakly acidic cation-exchange resin columns (TSKgel OApak-A or TSKgel Super IC-A/C). weakly acidic eluent (benzoic acid), and conductimetric detection. Particle size and cation-exchange capacity were 5 microm and 0.1 meq./ml for TSKgel OApak-A and 3 microm and 0.2 meq./ml for TSKgel Super IC-A/C, respectively. A dilute eluent (1.0-2.0 mM) of benzoic acid was effective for the high resolution and highly conductimetric detection of the carboxylic acids. The good separation of isobutyric and n-butyric acids was performed using the TSKgel Super IC-A/C column (150 mm x 6.0 mm i.d. x 2). The simple and good chromatograms were obtained by the optimized ion-exclusion chromatography conditions for real samples from mesophilic anaerobic digestors, thus the aliphatic carboxylic acids were successfully determined without any interferences.

  2. Determination of free amino acids in burley tobacco by high performance liquid chromatography

    Science.gov (United States)

    Jing, Yanqiu; Zhang, Baolin; Yuan, Xiuxiu; Gao, Yuzhen; Lu, Ping; Wang, Weifeng; Xu, Min

    2015-01-01

    A reversed-phase high performance liquid chromatographic method was developed for determining free amino acids in burley tobacco. The test was done by OPA/3-mercaptopropionic acid as the pre-column derivatizing reagent. Chromatographic column was Elitte C18 column (4.6 mm × 250 mm i.d., 5 μm). Mobile phase A was 18 mol/l NaAc (pH7.2) including 0.002%(v/v) triethylamine and 0.3%(v/v) furanidine. Mobile phase B was 100 mol/l NaAc (pH7.2)–acetonitrile–methanol (v/v = 1:2:2). The column temperature was 40 °C and the flow rate was 1.0 ml/min. The fluorescence detector was used with 350 nm excitation wave length and 450 nm emission wave length. The average recoveries of the method ranged from 95.3–100.7% with the relative standard deviation of 2.32–9.24%. The method is simple, accurate and has good repeatability. The results of the determination of seventeen kinds of free amino acids in burley leaves were produced by the way of different ratios of cake fertilizer and inorganic fertilizer. The results show that Aspartic acid has the highest content however ratio of cake fertilizer and inorganic fertilizer. The contents of most of the free amino acids are increased and then gradually decreased with the increase in organic manure. The contents of most of the free amino acids are very close at 15:85% ratio and 30:70% ratio of cake fertilizer and inorganic fertilizer. The total amount of free amino acids is the highest at 30:70% ratio of cake fertilizer and inorganic fertilizer. Considering comprehensively, the quality of burley leaves is the best at 30:70% ratio of cake fertilizer and inorganic fertilizer. PMID:26858568

  3. Quantitative determination of phases in ZrO{sub 2} (MgO) (Y{sub 2}O{sub 3}) using the Rietveld method; Determinacao quantitativa de fases em ZrO{sub 2} - MgO - Y{sub 2}O{sub 3} utilizando o metodo de Rietveld

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Antonio Carlos de

    2007-07-01

    The key objective of this work is the crystallographic characterization of the zircon co-doped with Yttria and magnesium with the application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon monoclinic, tetragonal, and cubic). Samples of zircon polymorph were obtained from zircon doped with Yttria and magnesium at defined molar concentrations. The zircon polymorph stability during subeutetoid aging at 1350 deg C were investigated to determine ZrO{sub 2} - MgO - Y{sub 2}0{sub 3} phases degradation and to define the solid solutions stability environment. ZrO{sub 2} powders doped with 8 mol por cent of MgO and 1 mol por cent of Y{sub 2}O{sub 3}, and 9 mol por cent of MgO and 0 mol por cent of Y{sub 2}O{sub 3} have been prepared by chemical route using the co-precipitation method. These samples have been calcinate at 550 deg C, sintered at 1500 deg C and characterized by the Rietveld method using the X-ray diffraction data. The variation of the lattice parameter, changes in the phase composition and their microstructures are discussed. The application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon tetragonal and cubic) reveals no formation of tetragonal phase and indicating that the matrix is the cubic phase with low concentration of monoclinic phase.(author)

  4. Development of a fission track register dry-method for uranium determination in biological and environmental samples; Desenvolvimento do metodo a seco de registro de tracos de fissao a ser empregado na determinacao de uranio em diversos tipos de amostras biologicas e ambientais

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Ione Makiko [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Geraldo, Luiz Paulo [Universidade Catolica de Santos (UNISANTOS), SP (Brazil). Instituto de Pesquisas Cientificas

    2002-07-01

    In the present work, it was developed a relatively quick and reproducible method for the determination of uranium content, in the ppb level, to be employed in the study of several biological and environmental samples. The technique employed was the fission-track registration in a polycarbonate plastic sheet, commercially known as Makrofol KG (dry-method), together with an automatic discharge chamber system for fission-track counting, using as electrode an aluminized Mylar foil. 5{mu}l droplet of the standard sample solutions, in the form of uranyl nitrate, with U concentrations ranging from 12x10{sup -6} to 50x10{sup -6} g/l, were deposited on Makrofol KG plastic foils, together with 2{mu}l of a 1% cyastat solution (wetting agent), in order to reduce the droplet surface tension. During the deposition, the whole droplet was carefully scattered in such way that large deposit areas, around 7cm{sup 2} were obtained. After evaporation (7 minutes) under a bulb lamp (250 W), the samples were covered by an extremely thin layer (20 {mu}g/cm{sup 2}) of collodion (pyroxylin) in order to fix the dried deposits on the plastic foils. Sets of 12 piled up samples were simultaneously irradiated with neutrons produced by the IPEN IEA-R1 reactor, a 2 MW pool type research reactor. The calibration curve obtained is presented with a discussion of the experimental uncertainties involved. (author)

  5. Determination of D/L-amino acids by zero needle voltage electrospray ionisation

    DEFF Research Database (Denmark)

    Sørensen, Morten B.; Aaslo, Per; Egsgaard, Helge;

    2008-01-01

    a mechanism related to sonic spray ionization. The utility of the zero needle voltage ESI was illustrated by determining the age of a human tooth by the aspartic acid epimerization method. The procedure involved separating the D- and L-aspartic acid of a tooth extract on a chiral HPLC column and detection......Ion formation may be made more efficient than in normal electrospray ionization (ESI) for certain classes of compounds, such as the polar amino acids Glu, Asn, His, Ser, Asp, Arg, Tyr and Lys, by adjusting the voltage of a normal ESI interface needle to zero voltage. For aspartic acid (Asp......) the gain in signal-to-noise (S/N) ratio of the liquid chromatography/mass spectrometry (LC/MS) chromatograms obtained in the selective ion monitoring (SIM) mode (m/z 134) with zero needle potential was 40-50 times higher than detection at 4 kV. Ion formation at zero potential is likely to follow...

  6. Fluorescence Quenching Investigation for Janus Green B and used as Probe in Determination of Nucleic Acids

    Institute of Scientific and Technical Information of China (English)

    陈莉华; 刘六战; 沈含熙

    2005-01-01

    Fluorescence quenching of janus green B (JGB) in sodium dodecyl sulfate (SDS) micelle by nucleic acids (DNA) was studied using UV-vis absorption, steady state fluorescence emission methods and lifetime measurements. In the SDS micelle, weak fluorescence of JGB was enhanced, and the maximum emission shifted from 425 to 410 nm. In the presence of DNA, the fluorescence of JGB was quenched. Linear relationships between the fluorescence quenching (F0/F) and concentrations of DNA were observed in the range of 2.4×10-8 to 1.08×10-7mol·L-1 for calf thymus nucleic acids (ct DNA) and 1.9×10-8 to 3.8×10-8 mol·L-1 for fish sperm nucleic acids (fs DNA) when 2.5×10-5 mol·L-1 JGB was employed. The limit detection were 1.3×10-8 mol·L-1 for ct DNA and 6.4×10-9 mol·L-1 for fs DNA. At high DNA concentration, there was a systematic deviation from the Stem-Volmer equation due to the static and dynamic quenching occurring simultaneously. The proposed method was applied to the determination of the nucleic acids in chicken blood extraction and the analytical results were in good agreement with the UV-method.

  7. Hexuronic acid stereochemistry determination in chondroitin sulfate glycosaminoglycan oligosaccharides by electron detachment dissociation.

    Science.gov (United States)

    Leach, Franklin E; Ly, Mellisa; Laremore, Tatiana N; Wolff, Jeremy J; Perlow, Jacob; Linhardt, Robert J; Amster, I Jonathan

    2012-09-01

    Electron detachment dissociation (EDD) has previously provided stereo-specific product ions that allow for the assignment of the acidic C-5stereochemistry in heparan sulfate glycosaminoglycans (GAGs), but application of the same methodology to an epimer pair in the chondroitin sulfate glycoform class does not provide the same result. A series of experiments have been conducted in which glycosaminoglycan precursor ions are independently activated by electron detachment dissociation (EDD), electron induced dissociation (EID), and negative electron transfer dissociation (NETD) to assign the stereochemistry in chondroitin sulfate (CS) epimers and investigate the mechanisms for product ion formation during EDD in CS glycoforms. This approach allows for the assignment of electronic excitation products formed by EID and detachment products to radical pathways in NETD, both of which occur simultaneously during EDD. The uronic acid stereochemistry in electron detachment spectra produces intensity differences when assigned glycosidic and cross-ring cleavages are compared. The variations in the intensities of the doubly deprotonated (0,2)X(3) and Y(3) ions have been shown to be indicative of CS-A/DS composition during the CID of binary mixtures. These ions can provide insight into the uronic acid composition of binary mixtures in EDD, but the relative abundances, although reproducible, are low compared with those in a CID spectrum acquired on an ion trap. The application of principal component analysis (PCA) presents a multivariate approach to determining the uronic acid stereochemistry spectra of these GAGs by taking advantage of the reproducible peak distributions produced by electron detachment.

  8. The determination of titratable acidity and total tannins in red wine

    Directory of Open Access Journals (Sweden)

    Rajković Miloš B.

    2009-01-01

    Full Text Available Titration acidity and content of total tannins in mass-market red wines are analyzed in this paper. The content of total acids in wine, expressed through wine acid, was analyzed by potentiometric titration on 7.00 pH value. According to titratable acidity in analyzed wines, all wines (only with analyzed parameters according to Regulations about wine quality. The analysis of differential potentiometric curves shows that these curves can give the answer to the question if non organic substances, amino groups and phenols are present in wine in large quantity, as they are always present in wine. However it doesn't give the clear answer which substances are present in analyzed samples. The answer to this question can be received only by the method of ionic chromatography. The content of total tannins shows short time of storage in wine cellars so wine wasn't stored long enough, i.e. they are commercial wines made for mass market production and consumption. Although they have less content of total tannin materials of given values, wine taste gives the correlation with other polyphenol materials that only give odour, aroma and 'bouquet' to wine. The relative error of mean value is very low which indicates the reproduction of results and reliability of the method of determination of total tannins in red wine.

  9. Determination of hydroxy acids in cosmetics by chemometric experimental design and cyclodextrin-modified capillary electrophoresis.

    Science.gov (United States)

    Liu, Pei-Yu; Lin, Yi-Hui; Feng, Chia Hsien; Chen, Yen-Ling

    2012-10-01

    A CD-modified CE method was established for quantitative determination of seven hydroxy acids in cosmetic products. This method involved chemometric experimental design aspects, including fractional factorial design and central composite design. Chemometric experimental design was used to enhance the method's separation capability and to explore the interactions between parameters. Compared to the traditional investigation that uses multiple parameters, the method that used chemometric experimental design was less time-consuming and lower in cost. In this study, the influences of three experimental variables (phosphate concentration, surfactant concentration, and methanol percentage) on the experimental response were investigated by applying a chromatographic resolution statistic function. The optimized conditions were as follows: a running buffer of 150 mM phosphate solution (pH 7) containing 0.5 mM CTAB, 3 mM γ-CD, and 25% methanol; 20 s sample injection at 0.5 psi; a separation voltage of -15 kV; temperature was set at 25°C; and UV detection at 200 nm. The seven hydroxy acids were well separated in less than 10 min. The LOD (S/N = 3) was 625 nM for both salicylic acid and mandelic acid. The correlation coefficient of the regression curve was greater than 0.998. The RSD and relative error values were all less than 9.21%. After optimization and validation, this simple and rapid analysis method was considered to be established and was successfully applied to several commercial cosmetic products.

  10. Docosapentaenoic acid (DPA) is a critical determinant of cubic membrane formation in amoeba Chaos mitochondria.

    Science.gov (United States)

    Deng, Yuru; Almsherqi, Zakaria A; Shui, Guanghou; Wenk, Markus R; Kohlwein, Sepp D

    2009-09-01

    Very long-chain polyunsaturated fatty acids (VLC-PUFAs), such as docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA), have recently made it to the realm of "magical molecules" based on their multiple presumably beneficial effects in biological systems, making these PUFAs particularly interesting in biomedicine. Their specific biological functions, however, remain enigmatic. Here we provide evidence derived from studies in the amoeba Chaos that indicates a structural role for omega-6 DPA in cell membrane organization, which may help to explain the multiple diverse effects of VLC-PUFA in healthy and diseased states. Amoeba Chaos mitochondria undergo a remarkable and reversible morphological transition into cubic morphology on starvation. This morphological transition is reflected in major changes in fatty acid and lipid composition, as determined by gas liquid chromatography and mass spectrometry, in particular by a drastic increase in C22:5 modified phosphatidylcholine plasmalogen, phosphatidylethanolamine plasmalogen, and phosphatidylinositol species. Liposomes produced in vitro from lipids of starved amoeba cells show a high propensity to form hexagonal tubular and cubic morphologies. Addition of omega-6 DPA, but not of omega-3 DPA, to the cell culture also induced mitochondrial membrane transformation into cubic morphology in fed cells, demonstrating for the first time an important structural role of omega-6 DPA-containing lipids in cell membrane organization.

  11. Determination of dissociation parameters of weak acids in different media according to the isohydric method.

    Science.gov (United States)

    Michałowski, Tadeusz; Pilarski, Bogusław; Asuero, Agustin G; Dobkowska, Agnieszka; Wybraniec, Sławomir

    2011-10-30

    The isohydricity (pH constancy) principle is referred to the pair of solutions: weak acid (HL, C(0)mol/L) and strong acid (HB, C mol/L) when mixed e.g., according to titrimetric mode. Such a case takes place if the relation C(0)=C+C(2) × 10(pK(1)) is valid, where pK(1)=-log K(1), K(1) - dissociation constant for a weak monoprotic acid HL. This principle, outlined and formulated in earlier paper (Michałowski et al., Talanta 82 (2010) 1965), is the basis for a sensitive method of pK(1) determination, confirmed for a series of weak acids in presence of basal electrolytes or in water+organic solvent (dimethyl sulphoxide, methanol, isopropanol) media. The results of titrations were elaborated according to principles of regression analysis, with use of least squares method. A new criterion for precision of the results obtained according to this method is formulated. The pK(1) values obtained are comparable with ones found in literature.

  12. Determination of herbicides paraquat, glyphosate, and aminomethylphosphonic acid in marijuana samples by capillary electrophoresis.

    Science.gov (United States)

    Lanaro, Rafael; Costa, José L; Cazenave, Silvia O S; Zanolli-Filho, Luiz A; Tavares, Marina F M; Chasin, Alice A M

    2015-01-01

    In this work, two methods were developed to determine herbicides paraquat, glyphosate, and aminomethylphosphonic acid (AMPA) in marijuana samples by capillary electrophoresis. For paraquat analysis, sample was extracted with aqueous acetic acid solution and analyzed by capillary zone electrophoresis with direct UV detection. The running electrolyte was 50 mmol/L phosphate buffer (pH 2.50). For glyphosate and AMPA, indirect UV/VIS detection was used, as these substances do not present chromophoric groups. Samples were extracted with 5 mmol/L hydrochloric acid. The running electrolyte was 10 mmol/L gallic acid, 6 mmol/L TRIS, and 0.1 mmol/L CTAB (pH = 4.7). The methods presented good linearity, precision, accuracy, and recovery. Paraquat was detected in 12 samples (n = 130), ranging from 0.01 to 25.1 mg/g. Three samples were positive for glyphosate (0.15-0.75 mg/g), and one sample presented AMPA as well. Experimental studies are suggested to evaluate the risks of these concentrations to marijuana user.

  13. HPLC DETERMINATION OF D-PANTHENOL AND GLYCYRRHETINIC ACID FROM A HERBAL ANTI-HERPETIC SUPPLEMENT

    Directory of Open Access Journals (Sweden)

    Elena Gabriela Oltean

    2016-12-01

    Full Text Available HPLC was used for the quantitative determination of panthenol and glycyrrhetinic acid in an herbal antiherpetic supplement containing panthenol (B5 provitamin and alcoholic extract of Glycyrrhiza glabra. For the determination of panthenol, the separation was carried out on a Kromasil 60-S Hilic D C18 column (250x4.6 mm, 5 µm, with methanol – 20 mM potassium phosphate dibasic, pH 6 (10:90, volume ratio as the mobile phase. The detection wavelength was set at 210 nm. Flow was 1 mL·min-1 and the column temperature was maintained at (30±0.5 °C. For glycyrrhetinic acid, a Hypersil C18 BDS column (250x4.6 mm, 5 µm with acetonitrile – 0.1% phosphoric acid in water (75:25, volume ratio isocratic elution. The detection wavelength was set at 250 nm. Flow was 1 mL·min-1 and the column temperature was maintained at (30±0.5 °C.

  14. Fluorometric determination of acid proteinase activity in Candida albicans strains from diabetic patients with vulvovaginal candidiasis.

    Science.gov (United States)

    Yildirim, Zuhal; Kilic, Nedret; Kalkanci, Ayse

    2011-09-01

    Vulvovaginal candidiasis is one of the most frequent disorders in obstetrics and gynaecology. Approximately three-quarters of all adult women experience at least one episode of vulvovaginal candidiasis during their life span. Diabetes mellitus (DM) increases the rate of vaginal colonisation and infection with Candida species. The secreted acid proteinase might be especially relevant in the pathogenesis of vulvovaginal candidiasis. The aim of this study was to determine the acid proteinase activity in the samples of Candida albicans from diabetic patients with vulvovaginal candidiasis by a fluorometric method. Vaginal swabs were taken from 33 women (aged between 22 and 57 years) having symptoms of vaginitis. Patients were divided into three groups: control group, controlled diabetic group and uncontrolled diabetic group. The proteinase activity in the culture supernatants was determined by a modified fluorometric method. Acid proteinase activities were significantly increased in the uncontrolled diabetic group in comparison with both the control group and the controlled diabetic group (P albicans pathogenesis in diabetic patients. Improving glucose control may reduce the risk of Candida colonisation and potentially symptomatic infection, among women with diabetes and hence may be useful even for weaker enzyme activity measurements.

  15. Determination of boron in produced water using the carminic acid assay.

    Science.gov (United States)

    Floquet, Cedric F A; Sieben, Vincent J; MacKay, Bruce A; Mostowfi, Farshid

    2016-04-01

    Using the carminic acid assay, we determined the concentration of boron in oilfield waters. We investigated the effect of high concentrations of salts and dissolved metals on the assay performance. The influence of temperature, development time, reagent concentration, and water volume was studied. Ten produced and flowback water samples of different origins were measured, and the method was successfully validated against ICP-MS measurements. In water-stressed regions, produced water is a potential source of fresh water for irrigation, industrial applications, or consumption. Therefore, boron concentration must be determined and controlled to match the envisaged waste water reuse. Fast, precise, and onsite measurements are needed to minimize errors introduced by sample transportation to laboratories. We found that the optimum conditions for our application were a 5:1 mixing volume ratio (reagent to sample), a 1 g L(-1) carminic acid concentration in 99.99% sulfuric acid, and a 30 min reaction time at ambient temperature (20 °C to 23 °C). Absorption values were best measured at 610 nm and 630 nm and baseline corrected at 865 nm. Under these conditions, the sensitivity of the assay to boron was maximized while its cross-sensitivity to dissolved titanium, iron, barium and zirconium was minimized, alleviating the need for masking agents and extraction methods.

  16. An Exact Method to Determine the Conductivity of Aqueous Solutions in Acid-Base Titrations

    Directory of Open Access Journals (Sweden)

    Norma Rodríguez-Laguna

    2015-01-01

    Full Text Available Several works in the literature show that it is possible to establish the analytic equations to estimate the volume V of a strong base or a strong acid (Vb and Va, resp. being added to a solution of a substance or a mix of substances during an acid-base titration, as well as the equations to estimate the first derivative of the titration plot dpH/dV, and algebraic expressions to determine the buffer β capacity with dilution βdil. This treatment allows establishing the conditions of thermodynamic equilibria for all species within a system containing a mix of species from one or from various polyacid systems. The present work shows that it is possible to determine exactly the electric conductivity of aqueous solutions for these Brønsted acid-base titrations, because the functional relation between this property and the composition of the system in equilibrium is well known; this is achieved using the equivalent conductivity λi values of each of the ions present in a given system. The model employed for the present work confirms the experimental outcomes with the H2SO4, B(OH3, CH3COOH, and H3PO4 aqueous solutions’ titration.

  17. [Simultaneous determination of stevioside, rebaudioside A and glycyrrhizic acid in foods by HPLC].

    Science.gov (United States)

    Sakamaki, Narue; Matsumoto, Hiroko; Hagino, Kayo; Nakazato, Mitsuo; Yasuda, Kazuo

    2004-04-01

    A method for the simultaneous determination of stevioside (Stev), rebaudioside A (RebA) and glycyrrhizic acid (GA) in foods was developed. These sweeteners were extracted from foods, except for dried fishes and shellfishes, by dialysis against Tris-HCl buffer (pH 9.0). Dried fishes and shellfishes were extracted with Tris-HCl buffer--methanol (2:8). The extracts were cleaned up with an Oasis MAX cartridge. The cartridge was washed with 0.05 mol/L sodium acetate (pH 4.0)--methanol (19:1), and the three sweeteners were eluted with 0.1 mol/L phosphoric acid--acetonitrile (1:1). Stev, RebA and GA in the eluate were chromatographed on a Develosil RPAQUEOUS-AR-5 (4.6 mm i.d. x 250 mm) column with 0.02 mol/L phosphoric acid-acetonitrile--methanol (90:55:5) as a mobile phase and monitored at 210 nm for Stev and RebA, and at 254 nm for GA. The recoveries of Stev, RebA and GA from 8 kinds of foods spiked at the level of 0.1 g/kg were 81.7-101%, 81.5-100% and 78.6-95.0%, respectively. The determination limits were 0.01 g/kg in samples.

  18. Simultaneous separation and quantitative determination of monosaccharides, uronic acids, and aldonic acids by high performance anion-exchange chromatography coupled with pulsed amperometric detection in corn stover prehydrolysates

    Directory of Open Access Journals (Sweden)

    Xing Wang

    2012-11-01

    Full Text Available A method for simultaneous separation and quantitative determination of arabinose, galactose, glucose, xylose, xylonic acid, gluconic acid, galacturonic acid, and glucuronic acid was developed by using high performance anion-exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD. The separation was performed on a CarboPacTM PA-10 column (250 mm × 2 mm with a various gradient elution of NaOH-NaOAc solution as the mobile phase. The calibration curves showed good linearity (R2 ≥ 0.9993 for the monosaccharides, uronic acids, and aldonic acids in the range of 0.1 to 12.5 mg/L. The detection limits (LODs and the quantification limits (LOQs were 4.91 to 18.75 μg/L and 16.36 to 62.50 μg/L, respectively. Relative standard deviations (RSDs of the retention times and peak areas for the seven consecutive determinations of an unknown amount of mixture were 0.15% to 0.44% and 0.22% to 2.31%, respectively. The established method was used to separate and determine four monosaccharides, two uronic acids, and two aldonic acids in the prehydrolysate from dilute acid steam-exploded corn stover within 21 min. The spiked recoveries of monosaccharides, uronic acids, and aldonic acids ranged from 91.25% to 108.81%, with RSDs (n=3 of 0.04% ~ 6.07%. This method was applied to evaluate the quantitative variation of sugar and sugar acid content in biomass prehydrolysates.

  19. Flow-injection chemiluminescence determination of acetylsalicylic acid based on its enhancing effect on the lucigenin–hydrogen peroxide system.

    Science.gov (United States)

    Wabaidur, S M; Alam, S M; Alothmana, Z A; Eldesokya, Gaber

    2014-09-01

    A sensitive flow-injection chemiluminescence method for the determination of acetylsalicylic acid is described. It is based on the enhanced chemiluminescent emission of the alkaline lucigenin–H2O2 system by acetylsalicylic acid. The difference in chemiluminescent intensity of alkaline lucigenin–H2O2 in the presence of acetylsalicylic acid from that in the absence of acetylsalicylic acid was linear at acetylsalicylic acid concentrations in the range of 0.0029–47.37 μg/mL, with detection and quantification limits of 0.0011 and 0.0029 μg/mL, respectively. The correlation coefficient of the working curve was 0.9983. The relative standard deviation (n = 10) for 25 μg/mL acetylsalicylic acid is 1.95%. All experimental parameters were optimized. The method was successfully applied to the determination of acetylsalicylic acid in pharmaceutical preparations. The recovery results obtained by the method were satisfactory.

  20. Sensitive spectrophotometric determination of ascorbic acid in drugs and foods using surface plasmon resonance band of silver nanoparticles

    Directory of Open Access Journals (Sweden)

    Kobra Zarei

    2015-12-01

    Full Text Available A simple and sensitive procedure was proposed for spectrophotometric determination of ascorbic acid. It was found that the reduction of Ag+ to silver nanoparticles (Ag-NPs by ascorbic acid in the presence of polyvinylpyrrolidone (PVP as a stabilizing agent produce very intense surface plasmon resonance peak of Ag-NPs. The plasmon absorbance of the Ag-NPs at λ = 440 nm allows the quantitative spectrophotometric detection of the ascorbic acid. The calibration curve was linear with concentration of ascorbic acid in the range of 0.5–60 μM. The detection limit was obtained as 0.08 μM. The influence of potential interfering substances on the determination of ascorbic acid was studied. The proposed method was successfully applied for the determination of ascorbic acid in some powdered drink mixtures, commercial orange juice, natural orange juice, vitamin C injection, effervescent tablet, and multivitamin tablet.

  1. Determination of Organic Acids in Root Exudates by High Performance Liquid Chromatography:Ⅱ.Influence of Several Testing COnditions

    Institute of Scientific and Technical Information of China (English)

    SHENJIANBO; ZHANGFUSUO; 等

    1999-01-01

    Effects of column temperature and flow rate on separation of organic acids were studied by determining nine low-molecular-weight organic acids on reversed-phase C18 column using high performace liquid chromatography(HPLC) with a wavelength of UV(ultraviolet)214 nm and a mobile phase of 18 mmol L-1 KH2PO4 buffer solution (pH2.1).The thermal stabiltiy of organic acids was determined by comparing the recoveries of organic acids in different temperature treatments.The relationships between column temperature,flow rate or solvent pH and retention time were analyzed.At low solvent pH,separatioin efficiency of organic acids was increased by raising the flow rate of the solvent because of lowering the retention time or organic acids.High column temperature was unfavorable for the separation of organic acids.The separating effect can be enhanced through reducing column temperature in organic acid determination due to increasing retention time.High thermal stability of organic acids with low concentrations was observed at temperature of 40℃-45℃,Sensitivity and separation effect of organic acid determination by HPLC were clearly improved by a combination of raising flow rate and lowering column temperature at low solvent pH.

  2. Direct determination of creatinine based on poly(ethyleneimine)/phosphotungstic acid multilayer modified electrode.

    Science.gov (United States)

    Han, Ping; Xu, Shimei; Feng, Shun; Hao, Yanjun; Wang, Jide

    2016-05-01

    In this work, the direct determination of creatinine was achieved using a poly(ethyleneimine)/phosphotungstic acid multilayer modified electrode with the assistance of Copper(II) ions by cyclic voltammetry. The quantity of creatinine were determined by measuring the redox peak current of Cu(II)-creatinine complex/Cu(I)-creatinine complex. Factors affecting the response current of creatinine at the modified electrode were optimized. A linear relationship between the response current and the concentration of creatinine ranging from 0.125 to 62.5μM was obtained with a detection limit of 0.06μM. The proposed method was applied to determine creatinine in human urine, and satisfied results were gotten which was validated in accordance with high performance liquid chromatography. The proposed electrode provided a promising alternative in routine sensing for creatinine without enzymatic assistance.

  3. Limiar de lactato em remadores: comparação entre dois métodos de determinação Umbral de lactato en remeros: comparacion entre dos metodos de determinación Lactate threshold in rowers: comparison between two methods of determination

    Directory of Open Access Journals (Sweden)

    Rafael Reimann Baptista

    2005-08-01

    lactato, la producción de potencia y frecuencia cardiaca, identificadas por el método Dmáx, fueron comparadas con el método AT4 en los grupos peso pesado (3,01 ± 0,73 vs. 4 mM, 268,33 ± 29,44 vs. 312 ± 44,02 W y 164 ± 4,81 vs. 174 ± 10,09 bpm, peso leve (2,51 ± 0,53 vs. 4 mM, 232,50 ± 15,00 vs. 277,50 ± 25,98 W y 160 ± 8,47 vs. 177 ± 3,79 bpm y femenino (3,21 ± 0,41 vs. 4 mM, 160 ± 14,41 vs. 167,50 ± 15,00 W y 175 ± 20,42 vs. 185 ± 12,12 bpm a través de un test-t de Student para muestras apareadas, siendo significativamente menores (P The objective of this study was to compare the 4 mM (AT4 and Dmax methods for lactate threshold determination. Ten male (23.7 ± 3.33 years and four female rowers (18 ± 0.81 years, divided into three groups: heavy weight (n = 6, light weight (n = 4, and female (n = 4, (87.23 ± 6.10, 73.22 ± 2.38, 63.27 ± 8.86 kg and 187.66 ± 1.63, 183 ± 6.05, 172 ± 5.16 cm respectively, were submitted to a maximal rowing ergometry, with initial workload of 130 to 150 W and increases of 30 to 50 W every 5 minutes, with 1 minute pause for blood sampling. Power output, heart rate and lactate values were determined at every workload and used for the determination of the thresholds according to both methods. Lactate concentration, power output and heart rate, identified by Dmax method were compared with the AT4 method in the heavy weight (3.01 ± 0.73 vs. 4 mM, 268.33 ± 29.44 vs. 312 ± 44.02 W and 164 ± 4.81 vs. 174 ± 10.09 bpm, light weight (2.51 ± 0.53 vs. 4 mM, 232.50 ± 15.00 vs. 277.50 ± 25.98 W and 160 ± 8.47 vs. 177 ± 3.79 bpm and female (3.21 ± 0.41 vs. 4 mM, 160 ± 14.41 vs. 167.50 ± 15.00 W and 175 ± 20.42 vs. 185 ± 12.12 bpm groups through the paired Student t-test, being significantly lower (p < 0.05 when the method Dmax was used. The results suggest that the AT4 method overestimates the variables analyzed in the lactate threshold when compared with the Dmax method.

  4. A method for determining an indicator of effective dose calculation due to inhalation of Radon and its progeny from in vivo measurements; Um metodo para determinar um indicador para calcular dose efetiva devida a inalacao de Radonio e seus descendentes utilizando medicoes in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Estrada, Julio Jose da Silva

    1994-07-01

    Direct measurement of the absolved dose to lung tissue from inhalation of radon and its progeny is not possible and must be calculated using dosimetric models, taking into consideration the several parameters upon which the dose calculation depends. To asses the dose due to inhalation of radon and its progeny, it is necessary to estimate the cumulative exposure. Historically, this has been done using WLM values estimated with measurements of radon concentration in air. The radon concentration in air varies significantly, however, in space with time, and the exposed individual is also constantly moving around. This makes it almost impossible to obtain a precise estimate of an individual's inhalation exposure. This work describes a pilot study to calculate lung dose from the deposition of radon progeny, via estimates of cumulative exposure derived from in vivo measurements of {sup 210} Pb, in subjects exposed to above-average radon and its progeny concentrations in their home environments. The measurements were performed in a whole body counter. With this technique, the exposed individuals become, in affect, their own samplers and dosimeters and the estimate of cumulative exposure is not affected by the variation of the atmospheric concentration of radon and its progeny in time and space. Forty individuals identified as living in homes with radon levels ranging from about 740 Bq/m{sup 3} to 150.000 Bq/m{sup 3} were measured. Also, additional 34 measurements were made on personnel from NYUMC/NIEM who live in a residential area surrounding the laboratory in which the levels of radon have been shown to be at below average values. To realize these measurements a methodology was developed to determine the subject's background, using a head phantom made with a cubic plastic container containing known amounts of potassium and calcium dissolved in four liters of water. The effective doses calculated from the in vivo measurements are compared to effective doses

  5. Microwave-assisted extraction versus Soxhlet extraction to determine triterpene acids in olive skins.

    Science.gov (United States)

    Fernandez-Pastor, Ignacio; Fernandez-Hernandez, Antonia; Perez-Criado, Sergio; Rivas, Francisco; Martinez, Antonio; Garcia-Granados, Andres; Parra, Andres

    2017-03-01

    Microwave-assisted extraction is compared with a more classical technique, Soxhlet extraction, to determine the content of triterpene acids in olive skins. The samples used in their original unmilled state and milled were extracted with ethyl acetate or methanol as solvents. The optimized operating conditions (e.g., amount and type of solvent, and time and temperature of extractions) to attain the better extraction yields have been established. For the identification and quantitation of the target compounds, an ultra high performance liquid chromatography with tandem mass spectrometry method was employed. The best results were achieved using the microwave-assisted extraction technique, which was much faster than the Soxhlet extraction method, and showed higher efficiency in the extraction of the triterpenic acids (oleanolic and maslinic).

  6. HPTLC-densitometry determination of triterpenic acids in Origanum vulgare, Rosmarinus officinalis and Syzygium aromaticum.

    Science.gov (United States)

    Nowak, Renata; Wójciak-Kosior, Magdalena; Sowa, Ireneusz; Sokołowska-Krzaczek, Anna; Pietrzak, Wioleta; Szczodra, Aleksandra; Kocjan, Ryszard

    2013-01-01

    Spices play an important role in the chemoprevention and they can be a rich source of biologically active compounds such as triterpenes in the human diet. A method based on high performance thin-layer chromatography combined with densitometry for determination of ursolic and oleanolic acids in some common spices was elaborated. The prechromatographic derivatization with 1% of iodine solution was used to enable simultaneous analysis of these triterpenes. The extracts were separated on HPTLC silica gel 60 F254 plates with use of mobile phase consisting of toluene-petroleum ether-ethyl acetate-acetonitrile 5: 5: 1: 0.3 (v/v/v/v). After drying, the plates were sprayed with 10% (v/v) ethanol solution of sulfuric acid (VI) and heated to 120 degrees C for 3 min. Quantification was performed in fluorescence/reflectance mode at a wavelength of 400 nm using a computer-controlled densitometer Desaga CD 60.

  7. Fast and Sensitive Method for Determination of Domoic Acid in Mussel Tissue

    Directory of Open Access Journals (Sweden)

    Elena Barbaro

    2016-01-01

    Full Text Available Domoic acid (DA, a neurotoxic amino acid produced by diatoms, is the main cause of amnesic shellfish poisoning (ASP. In this work, we propose a very simple and fast analytical method to determine DA in mussel tissue. The method consists of two consecutive extractions and requires no purification steps, due to a reduction of the extraction of the interfering species and the application of very sensitive and selective HILIC-MS/MS method. The procedural method was validated through the estimation of trueness, extract yield, precision, detection, and quantification limits of analytical method. The sample preparation was also evaluated through qualitative and quantitative evaluations of the matrix effect. These evaluations were conducted both on the DA-free matrix spiked with known DA concentration and on the reference certified material (RCM. We developed a very selective LC-MS/MS method with a very low value of method detection limit (9 ng g−1 without cleanup steps.

  8. An Amperometric Biosensor for Uric Acid Determination Prepared From Uricase Immobilized in Polyaniline-Polypyrrole Film

    Directory of Open Access Journals (Sweden)

    Fatma Arslan

    2008-09-01

    Full Text Available A new amperometric uric acid biosensor was developed by immobilizing uricase by a glutaraldehyde crosslinking procedure on polyaniline-polypyrrole (pani-ppy composite film on the surface of a platinum electrode. Determination of uric acid was performed by the oxidation of enzymatically generated H2O2 at 0.4 V vs. Ag/AgCl. The linear working range of the biosensor was 2.5×10-6 – 8.5×10-5 M and the response time was about 70 s. The effects of pH, temperature were investigated and optimum parameters were found to be 9.0, 55 oC, respectively. The stability and reproducibility of the enzyme electrode have been also studied.

  9. Using Capillary Electrophoresis to Determine the Purity of Acetylsalicylic Acid Synthesized in the Undergraduate Laboratory

    Science.gov (United States)

    Welder, Frank; Colyer, Christa L.

    2001-11-01

    Capillary electrophoresis (CE), although a powerful analytical tool, has found only limited application in undergraduate laboratory study. In an effort to expose freshman and sophomore chemistry students to this technique, thereby giving them practical instrumental experience early in their careers, we propose to use CE in the analysis of student-synthesized acetylsalicylic acid (ASA). The synthesis of ASA from salicylic acid (SA) is a routine undergraduate laboratory, although students rarely have the opportunity to test the purity of their product. The CE method described herein provides students with a method to test purity and yield of their product and to determine the effect of aging on their sample. CE can accomplish this in a short period of time, with minimal disruption to the regular laboratory curriculum. Optimized separation conditions, limits of detection, and linear range for ASA and SA are also given.

  10. Determination of the Thermal Decomposition Products of Terephthalic Acid by Using Curie-Point Pyrolyzer

    Science.gov (United States)

    Begüm Elmas Kimyonok, A.; Ulutürk, Mehmet

    2016-04-01

    The thermal decomposition behavior of terephthalic acid (TA) was investigated by thermogravimetry/differential thermal analysis (TG/DTA) and Curie-point pyrolysis. TG/DTA analysis showed that TA is sublimed at 276°C prior to decomposition. Pyrolysis studies were carried out at various temperatures ranging from 160 to 764°C. Decomposition products were analyzed and their structures were determined by gas chromatography-mass spectrometry (GC-MS). A total of 11 degradation products were identified at 764°C, whereas no peak was observed below 445°C. Benzene, benzoic acid, and 1,1‧-biphenyl were identified as the major decomposition products, and other degradation products such as toluene, benzophenone, diphenylmethane, styrene, benzaldehyde, phenol, 9H-fluorene, and 9-phenyl 9H-fluorene were also detected. A pyrolysis mechanism was proposed based on the findings.

  11. Algerian mint species: high performance thin layer chromatography quantitative determination of rosmarinic acid and in vitro inhibitory effects on linoleic acid peroxidation

    Directory of Open Access Journals (Sweden)

    Brahmi Fatiha

    2014-12-01

    Full Text Available Objective: To determine the quantitative paremeters of rosmarinic acid in Algerian mints, Mentha spicata L. (M. spicata, Mentha pulegium L. and Mentha rotundifolia (L. Huds by high performance thin layer chromatography (HPTLC-densitometric method and screen the effects of these plant extracts on linoleic acid peroxidation. Methods: The analyses were performed on HPTLC silica gel 60 F254 plates with chloroform: acetone: formic acid (75:16.5:8.5, v/v as the mobile phase. Rosmarinic acid was determined in UV at 365 nm and fluorescence at λexc 325 nm with a 550 nm filter, respectively. The effects of plants extracts on linoleic acid peroxidation were measured by an indirect in vitro colorimetric method. Results: Chromatographic resolution permitted reliable quantification in both measurement modes and calibration curves were linear in a range of 150-1 000 ng/spot. M. spicata was found to contain significantly higher concentrations of rosmarinic acid. The densitometric quantification allowed the analysis of many samples in a short time with reasonable precision (total precision for Mentha spp extracts, 5.1% and 5.8% for UV and fluorescence detection, respectively. The HPTLC data, allied to assays of linoleic acid peroxidation prevention, suggested the potential of M. spicata (52% Trolox® equivalents as a natural source for inhibitors of lipid peroxidation. Conclusions: Densitometry can be used for routine determination and quality control of rosmarinic acid in herbal and formulations containing Mentha species.

  12. Algerian mint species:high performance thin layer chromatography quantitative determination of rosmarinic acid and in vitro inhibitory effects on linoleic acid peroxidation

    Institute of Scientific and Technical Information of China (English)

    Brahmi Fatiha; Madani Khodir; Stvigny Caroline; Chibane Mohamed; Duez Pierre

    2014-01-01

    Objective: To determine the quantitative paremeters of rosmarinic acid in Algerian mints,Mentha spicata L. (M. spicata), Mentha pulegium L. and Mentha rotundifolia (L.) Huds by high performance thin layer chromatography (HPTLC)-densitometric method and screen the effects of these plant extracts on linoleic acid peroxidation.Methods:The analyses were performed on HPTLC silica gel 60 F254 plates with chloroform:acetone: formic acid (75:16.5:8.5, v/v) as the mobile phase. Rosmarinic acid was determined in UV at 365 nm and fluorescence at λexc 325 nm with a 550 nm filter, respectively. The effects of plants extracts on linoleic acid peroxidation were measured by an indirect in vitro colorimetric method.Results:Chromatographic resolution permitted reliable quantification in both measurement modes and calibration curves were linear in a range of 150-1000 ng/spot. M. spicata was found to contain significantly higher concentrations of rosmarinic acid. The densitometric quantification allowed the analysis of many samples in a short time with reasonable precision (total precision for Mentha spp extracts, 5.1% and 5.8% for UV and fluorescence detection, respectively). The HPTLC data, allied to assays of linoleic acid peroxidation prevention, suggested the potential of M. spicata (52% Trolox®equivalents) as a natural source for inhibitors of lipid peroxidation.Conclusions:Densitometry can be used for routine determination and quality control of rosmarinic acid in herbal and formulations containing Mentha species.

  13. Adsorption of tannic acid on polyelectrolyte monolayers determined in situ by streaming potential measurements.

    Science.gov (United States)

    Oćwieja, M; Adamczyk, Z; Morga, M

    2015-01-15

    Physicochemical characteristics of tannic acid (tannin) suspensions comprising its stability for a wide range of ionic strength and pH were thoroughly investigated using UV-vis spectrophotometry, dynamic light scattering and microelectrophoretic measurements. These studies allowed to determine the hydrodynamic diameter of the tannic acid that was 1.63 nm for the pH range 3.5-5.5. For pH above 6.0 the hydrodynamic diameter significantly decreased as a result of the tannin hydrolysis. The electrophoretic mobility measurements confirmed that tannic acid is negatively charged for these values of pH and ionic strength 10(-4)-10(-2) M. Therefore, in order to promote adsorption of tannin molecules on negatively charged mica, the poly(allylamine hydrochloride) (PAH) supporting monolayers were first adsorbed under diffusion transport conditions. The coverage of polyelectrolyte monolayers was regulated by changing bulk concentration of PAH and the adsorption time. The electrokinetic characteristics of bare and PAH-covered mica were determined using the streaming potential measurements. The zeta potential of these PAH monolayers was highly positive, equal to 46 mV for ionic strength of 10(-2) M. The kinetics of tannin adsorption on these PAH supporting monolayers was evaluated by the in situ the streaming potential measurements. The zeta potential of PAH monolayers abruptly decreases with the adsorption of tannin molecules that was quantitatively interpreted in terms of the three-dimensional electrokinetic model. The acid-base characteristics of tannin monolayers were acquired via the streaming potential measurements for a broad range of pH. The obtained results indicate that it is possible to control adsorption of tannin on positively charged surfaces in order to designed new multilayer structures of desirable electrokinetic properties and stability.

  14. Age determination of marine sediments in the western North Pacific by aspartic acid chronology

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Naomi; Kusakabe, Masashi [Japan Marine Science and Technology Center, Yokosuka, Kanagawa (Japan); Handa, Nobuhiko; Oba, Tadamichi; Matsuoka, Hiromi; Kimoto, Katsunori

    1997-02-01

    The ages of fossil planktonic foraminifera, Pulleniatina obliquiloculata, in sediments (core 3bPC) from the western North Pacific were determined by aspartic acid chronology, which uses the racemization reaction rate constant of aspartic acid (k{sub Asp}). Aspartic acid racemization-based ages (Asp ages) ranged from 7,600 yrBP at the surface, to 307,000 yrBP at a depth of 352.9 cm in the sediments. This sediment core was also dated by the glacial-interglacial fluctuation of {sigma}{sup 18}O chronology, and the ages determined by both chronologies were compared. The ages derived from aspartic acid chronology and {sigma}{sup 18}O stratigraphy were more or less consistent, but there appeared to be some differences in age estimates between these two dating methods at some depths within the core. In the core top sediments, the likely cause for the age discrepancy could be the loss of the surface sediment during sampling of the core. At depths of 66.3 and 139 cm within the core, Asp ages indicated reduced sedimentation rates during ca. 60,000-80,000 yrBP and ca. 140,000-190,000 yrBP. The maximum age differences in both chronologies are 33,000 yr and 46,600 yr during each of these periods. These anomalous reductions in sedimentation rates occurring during these periods could possibly be related to some geological events, such as an increased dissolution effect of the calcium carbonate in the western North Pacific. Another possible reason for these age differences could be the unreliability in {sigma}{sup 18}O ages of core 3bPC as they were estimated by {sigma}{sup 18}O ages of another core, 3aPC. (author)

  15. Fabrication of multiwalled carbon nanotubes/polyaniline modified Au electrode for ascorbic acid determination.

    Science.gov (United States)

    Chauhan, Nidhi; Narang, Jagriti; Pundir, C S

    2011-05-07

    An ascorbate oxidase (AsOx) (E.C.1.10.3.3) purified from Lagenaria siceraria fruit was immobilized covalently onto a carboxylated multiwalled carbon nanotubes and polyaniline (c-MWCNT/PANI) layer electrochemically deposited on the surface of an Au electrode. The diffusion coefficient of ascorbic acid was determined as 3.05 × 10(-4) cm(2) s(-1). The behavior of different electrolytes on electro-deposition was also studied. An ascorbate biosensor was fabricated using a AsOx/c-MWCNT/PANI/Au electrode as a working electrode, Ag/AgCl (3 M/saturated KCl) as standard and Pt wire as an auxiliary electrode connected through a potentiostat. Linear range, response time and detection limit were 2-206 μM, 2 s and 0.9 μM respectively. The biosensor showed optimum response at pH 5.8 and in a broader temperature range (30-45 °C), when polarized at +0.6 V. The biosensor was employed for determination of ascorbic acid level in sera, fruit juices and vitamin C tablets. The sensor was evaluated with 91% recovery of added ascorbic acid in sera and 6.5% and 11.4% within and between batch coefficients of variation respectively for five serum samples. There was a good correlation (r = 0.98) between fruit juice ascorbic acid values by the standard 2,6-dichlorophenolindophenol (DCPIP) method and the present method. The enzyme electrode was used 200 times over a period of two months, when stored at 4 °C. The biosensor has advantages over earlier enzyme sensors in that it has no leakage of enzyme, due to the covalent coupling of enzyme with the support, lower response time, wider working range, higher storage stability and no interference by serum substances.

  16. Determination and Correlation of Solubility for D-Xylose in Volatile Fatty Acid Solvents

    Institute of Scientific and Technical Information of China (English)

    李涛; 陈飞雄; 江振西; 任保增

    2014-01-01

    The solubility of D-xylose in formic acid and binary solvents of formic acid with formic acid and acetic acid, propionic acid, n-butyric acid or isobutyric acid was measured in the temperature range from 300.35 to 325.05 K using the synthetic method by a laser monitoring technique at atmospheric pressure. The solid-liquid equilibrium data will provide essential support for industrial design and further theoretical study. The experimental data show that the solubility of D-xylose in formic acid and in the mixtures of formic acid+acetic acid (1︰1), formic acid+propionic acid (1︰1), formic acid+n-butyric acid (1︰1), and formic acid+isobutyric acid (1︰1) increases with temperature. The Apelblat equation, theλh model, and the ideal solution equation correlate the solubility data well.

  17. Multiwavelength spectrophotometric determination of acidity constants of 1-(2-thiazolylazo)-2-naphthol in methanol-water mixtures

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The acid-base properties of 1-(2-thiazolylazo)-2-naphthol (TAN) in mixtures of methanol-water at 25 ℃ and an ionic strength of 0.1 mol/L are studied by a multi-wavelength spectrophotometric method. The acidity constants of all related equilibria are estimated using the whole spectral fitting of the collected data to an established factor analysis model. DATAN program was used for determination of acidity constants. The corresponding pKa values in methanol-water mixtures were determined. There is a linear relationship between acidity constants and the mole fraction of methanol in the solvent mixtures.

  18. Determination of an ageing factor for lead/acid batteries. 1. Kinetic aspects

    Science.gov (United States)

    Armenta-Deu, C.; Donaire, T.

    The capacity of lead/acid batteries decreases with the number of cycles. This process is known as ageing. The reduction of capacity affects not only the operation time but also the performance of the accumulator and of the system attached to the battery. One of the main procedures affected by the battery ageing is the determination of the state-of-charge. In this paper, a parameter called 'ageing factor', fa, which represents the reduction of the available energy in lead/acid batteries, is introduced. A method to calculate this factory and its incidence on battery performance has also been developed. The method is intended to predict 'ageing' effects on lead/acid batteries as a non-destructive method, as well as on-line battery operation. The method is based on the effective reduction in electrolyte specific gravity in a fully charged lead/acid battery computed from the change of the slope of the electrolyte density during charge with the number of cycles, and the subsequent reduction in discharge time. A correlation process between the reduction of the energy delivered by the electrochemical cell, the reduction of the discharge time, and the apparent change of the slope of electrolyte density has been developed, resulting in an analytical expression that may be used to compute the effective reduction in available energy in lead/acid batteries. The results of the experiments have proven the merit of the proposed system: the predicted values are in good agreement with experimental data, the associated error in the a estimation being lower than 9%, a result which has been considered acceptable to validate the proposed method.

  19. A Doped Polyaniline Modified Electrode Amperometric Biosensor for Gluconic Acid Determination in Grapes

    Directory of Open Access Journals (Sweden)

    Donatella Albanese

    2014-06-01

    Full Text Available In winemaking gluconic acid is an important marker for quantitative evaluation of grape infection by Botrytis cinerea. A screen-printed amperometric bienzymatic sensor for the determination of gluconic acid based on gluconate kinase (GK and 6-phospho-D-gluconate dehydrogenase (6PGDH coimmobilized onto polyaniline/poly (2-acrylamido-2-methyl-1-propanesulfonic acid; PANI-PAAMPSA is reported in this study. The conductive polymer electrodeposed on the working electrode surface allowed the detection of NADH at low potential (0.1 V with a linear range from 4 × 10−3 to 1 mM (R2 = 0.99 and a sensitivity of 419.44 nA∙mM−1. The bienzymatic sensor has been optimized with regard to GK/6PGDH enzymatic unit ratio and ATP/NADP+ molar ratio which resulted equal to 0.33 and 1.2, respectively. Under these conditions a sensitivity of 255.2 nA∙mM−1, a limit of detection of 5 μM and a Relative Standard Deviation (RSD of 4.2% (n = 5 have been observed. Finally, the biosensor has been applied for gluconic acid measurements in must grape samples and the matrix effect has been taken into consideration. The results have been compared with those obtained on the same samples with a commercial kit based on a spectrophotometric enzyme assay and were in good agreement, showing the capability of the bienzymatic PANI-PAAMPSA biosensor for gluconic acid measurements and thus for the evaluation of Botrytis cinerea infection in grapes.

  20. Determination of true digestible amino acids of feedstuffs utilizing cecectomized roosters

    Directory of Open Access Journals (Sweden)

    Eliane Aparecida da Silva

    2012-09-01

    Full Text Available The objective of this study was to estimate the true digestibility coefficients of amino acids and digestible amino acid values of some poultry feedstuffs. The feedstuffs were: babassu meal, sunflower meal, corn gluten meal, babassu starchy meal, meat and bone meal, common beans, pearl millet and residues of cookies, pasta and bread. The precise feeding method of Sibbald was used with adult cecectomized Leghorn roosters distributed in a completely randomized design, consisting of ten treatments and six replications with a rooster in each. The treatments were represented by the feedstuffs evaluated. The roosters were kept in a period of fasting for 36 hours and then fed 30 grams of feed. Samples were collected during 56 hours. Simultaneously, six roosters were kept fasting to make corrections to the metabolic and endogenous losses of amino acids. At the end of collections, the excreta obtained were weighed, freeze-dried and subsequently processed, so laboratory analyses were carried out and the coefficients of true digestibility of amino acids were determined. The mean values of the coefficients of true digestibility of essential and non-essential amino acids in percentage were respectively: 0.702 and 0.652 for the babassu meal; 0.852 and 0.786 for the sunflower meal; 0.928 and 0.887 for the corn gluten meal; 0.797 and 0.720 for the meat and bone meal; 0.364 and 0.339 for ground raw beans; 0.924 and 0.837 for ground pearl millet; 0.839 and 0.810 for cookie residue; 0.929 and 0.914 for pasta residue; and 0.904 and 0.899 for bread residue.

  1. [Determination of clavulanic acid residue in milk by high performance liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Yang, Gang; Huang, Xianhui; Guo, Chunna; Fang, Qiuhua; He, Limin

    2012-06-01

    An analytical method was developed for the determination of clavulanic acid (CLAV) in milk by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). A 2 g milk sample was deproteinized by ethanol. The supernatant was transferred into a pear-shaped bottle to be evaporated to about 0.5 mL, and the residue was dissolved with ammonium acetate solution. The sample was determined by HPLC-MS/MS after the purification. The chromatographic separation was achieved on a Luna 5u C8 column using 0.1% formic acid in water and acetonitrile as mobile phases with gradient elution. The identification of CLAV was carried out by MS/MS equipped with electrospray ionization in negative scanning and multiple reaction monitoring (MRM) modes. Matrix-matched calibration standard was used for the quantification. The calibration curve showed perfect linear in the range of 10 - 400 microg/kg with the correlation coefficient of 0.999. The limit of detection (LOD, S/N > or = 3) was 10 microg/kg in milk, and the limit of quantification (LOQ, S/N > or = 10) was 20 microg/kg. The mean recoveries varied from 80.00% to 91.25% at the four spiked levels of LOQ, 1/2MRL (the maximum residue limit), MRL, and 2MRL with the relative standard deviations of 5.60% -8.77%. In conclusion, the established method can be applied for the determination of CLAV residues in milk.

  2. New method for the direct determination of dissolved Fe(III) concentration in acid mine waters

    Science.gov (United States)

    To, T.B.; Nordstrom, D.K.; Cunningham, K.M.; Ball, J.W.; McCleskey, R.B.

    1999-01-01

    A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II) >> Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes in Fe reduction-oxidation distribution. Complexed Fe(II) is cleanly removed using a silica-based, reversed-phase adsorbent, yielding excellent isolation of the Fe(III) complex. Iron(III) concentration is measured colorimetrically or by graphite furnace atomic absorption spectrometry (GFAAS). The method requires inexpensive commercial reagents and simple procedures that can be used in the field. Calcium(II), Ni(II), Pb(II), AI(III), Zn(II), and Cd(II) cause insignificant colorimetric interferences for most acid mine waters. Waters containing >20 mg of Cu/L could cause a colorimetric interference and should be measured by GFAAS. Cobalt(II) and Cr(III) interfere if their molar ratios to Fe(III) exceed 24 and 5, respectively. Iron(II) interferes when its concentration exceeds the capacity of the complexing ligand (14 mg/L). Because of the GFAAS elemental specificity, only Fe(II) is a potential interferent in the GFAAS technique. The method detection limit is 2 ??g/L (40 nM) using GFAAS and 20 ??g/L (0.4 ??M) by colorimetry.A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II)???Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes

  3. Determination of CYP4A11-catalyzed lauric acid 12-hydroxylation by high-performance liquid chromatography with radiometric detection.

    Science.gov (United States)

    Crespi, Charles L; Chang, Thomas K H; Waxman, David J

    2006-01-01

    Lauric acid serves as an endogenous substrate for the cytochrome P450 enzyme CYP4A11. A reverse-phase, high-performance liquid chromatography method is described for the quantification of 12-hydroxylauric acid formed enzymatically by incubation of 14C-labeled lauric acid with cDNA-expressed CYP4A11 or human liver microsomes. Analytical separation is achieved using a C18 column and a gradient of 30% acetonitrile and 2 mM perchloric acid to 100% methanol, using a detection scintillation counter. This method is applicable to enzymatic studies for determination of lauric acid 12-hydroxylation activity.

  4. Capillary isotachophoretic determination of flufenamic, mefenamic, niflumic and tolfenamic acid in pharmaceuticals.

    Science.gov (United States)

    Polásek, M; Pospísilová, M; Urbánek, M

    2000-08-01

    Anionic capillary isotachophoresis (ITP) with conductimetric detection has been used for determining selected non-steroid anti-inflammatory and analgesic drugs of the phenamate group, namely tolfenamic (I), flufenamic (II), mefenamic (III) and niflumic (IV) acid. Initially the pKa values (proton lost) of I-IV were determined as 5.11, 4.91, 5.39 and 4.31, respectively, by the UV spectrophotometry in aqueous 50% (w/w) methanol. The optimised ITP electrolyte system consisted of 10 mM HCl + 20 mM imidazole (pH 7.1) as the leading electrolyte and 10 mM 5,5'-diethylbarbituric acid (pH 7.5) as the terminating electrolyte. The driving and detection currents were 100 microA (for 450 s) and 30 microA, respectively (a single analysis took about 20 min). Under such conditions the effective mobilities of I-IV varied between 23.6 and 24.6 m2 V(-1) s(-1) (evaluated with orotic acid as the mobility standard). The calibration graphs relating the ITP zone length to the concentration of the analytes were rectilinear (r = 0.9987-0.9999) in the range 10-100 mg l(-1) of the drug standard. The R.S.D.s were 0.96-1.55% (n = 6) when determining 50 mg l(-1) of the analytes in pure test solutions. The method has been applied to the assay of the phenamates in six commercial mass-produced pharmaceutical preparations (Mobilisin gel and ointment, Lysalgo capsules, Nifluril cream, Niflugel gel, and Clotam capsules). According to the validation procedure based on the standard addition technique the recoveries were 98.4-104.3% of the drug and the R.S.D. values were 1.25-3.32% (n = 6).

  5. Determination of Organic Acids in Root Exudates by High Performance Liquid Chromatography:Ⅲ.Effects of Interfering Factors

    Institute of Scientific and Technical Information of China (English)

    SHENJIANBO; ZHANGFUSUO; 等

    1999-01-01

    A solution culture experiment was conducted to investigate the effects of collection time and interfering ions on separation and determination of low-molecular-weight organic acids in root exudates of soybean using the method for directly collecting root exudates.The suitable cooection time of root exudates and the interferiung ions affecting organic acid determination were determined.The method for removing the interfering ions was established and analyzed.The release amount of root exudates increased with the increase of collection time from 0 to 120min but decreased with increasing of collection time from 120to 240min.The maximum exuding amounts of organic acids were observed in root exudates at the collection time of 120min.There was a significant difference of organic acid components between the treatments of collection time of 120min and 240min,Citric acid was founnd only in the treatment of 120min collection time,NO3- was the main interfering ion in organic acid determination and had the same retention time as oxalic acid.Anion exchange resin(SAX)properly treated by HPLC(high performance liquid chromatography)solvent could remove NO3- anion in sample solution of root exudates,thus enhancing the recoveries of organic acids in root exudates.There was no significant effect of the chemicals added into sample solution such as H3PO4,SAX and KNO3 on the retention time of organic acids.

  6. "Determination of mycophenolic acid in human plasma by high-performance liquid chromatography"

    OpenAIRE

    "Mehdi Ahadi Barzoki; Mohammadreza Rouini; Kheirolla Gholami; Mahboob Lessan-Pezeshki; Saeed Rezaee

    2005-01-01

    A simple, sensitive and reproducible HPLC method is presented for determination of mycophenolic acid(MPA) in human plasma. Samples were prepared after precipitation of the plasma protein by addition of acetonitrile and naproxen was used as internal standard (I.S.). Separation was performed by reversedphase HPLC, using a Hamilton PRP-C18 Column, 51% acetonitrile and 49% potassium phosphate buffer (20 mM) at pH 3.0 as mobile phase, flow rate of 1.0 ml/min, and UV detection at 215 nm. MPA and I....

  7. Determination of talniflumate and niflumic acid in human plasma by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Kang, Wonku; Kim, Kibum

    2009-04-01

    A simple and rapid quantification method was developed for determining both talniflumate and niflumic acid in human plasma. After simple protein precipitation with acetonitrile, the analytes were chromatographed on a reversed-phase C(18) column and detected by LC/MS/MS with electrospray ionization. The assay accuracy and precision were within the FDA guidance for the analytical method validation. This method was used to measure the plasma concentrations of both compounds from healthy subjects after a single oral dose of talniflumate, 740 mg.

  8. Simultaneous Determination of Bismuth and Copper by Square Wave Voltammetry in The Presence of Ethylenediaminetetraacedic Acid

    OpenAIRE

    HASDEMİR, Erdoğan; KARABODUK, Kuddusi

    2010-01-01

    A sensitive and selective method for the simultaneous determination of copper and bismuth by square wave voltammetry (SWV) was developed using ethylenediaminetetraacedic acid (EDTA) as complexing agent. Factors affecting the pH and concentrations ratios of copper and bismuth were investigated. Optimal analytical conditions were  found to be: pH of 8.0, the ratio of [Cu2+]/[Bi3+] was 0.13-2.5. The limit of detection (3δ) was 1.26 × 10-7 mol dm-3 for copper,  1.30×10...

  9. New Method for the Determination of Ionization Constants of Polyprotic Weak Acid

    Institute of Scientific and Technical Information of China (English)

    王静康; 郝红勋

    2003-01-01

    A new method for the determination of ionization constants of polyprotic weak acids is presented.Based on dissociation equilibrium, mass balance and charge balance, the mathematic model is established and the non-linear least-squares Gauss-Newton method is applied to numerically solve the model equations. In order to get the concentration of hydrogen ion, the Debye-Huckel equation is used to calculate its activity coefficient. The ionization constants of H2SO3 and H2C2O4 obtained by this method are in good agreement with the literature values.

  10. Electrochemistry and analytical determination of lysergic acid diethylamide (LSD) via adsorptive stripping voltammetry.

    Science.gov (United States)

    Merli, Daniele; Zamboni, Daniele; Protti, Stefano; Pesavento, Maria; Profumo, Antonella

    2014-12-01

    Lysergic acid diethylamide (LSD) is hardly detectable and quantifiable in biological samples because of its low active dose. Although several analytical tests are available, routine analysis of this drug is rarely performed. In this article, we report a simple and accurate method for the determination of LSD, based on adsorptive stripping voltammetry in DMF/tetrabutylammonium perchlorate, with a linear range of 1-90 ng L(-1) for deposition times of 50s. LOD of 1.4 ng L(-1) and LOQ of 4.3 ng L(-1) were found. The method can be also applied to biological samples after a simple extraction with 1-chlorobutane.

  11. Application of HPLC for determination of phytic acid in the colonic epithelial Caco-2 cells.

    Science.gov (United States)

    Weglarz, Ludmiła; Parfiniewicz, Beata; Bat, Beata; Orchel, Arkadiusz; Dzierzewicz, Zofia; Wilczok, Tadeusz

    2004-12-01

    Phytic acid (myo-inositol hexaphosphate, IP6) is currently receiving a considerable interest because of its anticancer (preventive and therapeutic) potential against colon tumors and the need for methods of its determination. The aim of this study was to analyze the uptake of IP6 by human colon adenocarcinoma cells (Caco-2 cell line) and to evaluate the method of its intracellular quantification with the use of high performance liquid chromatography (HPLC) technique. Chromatographic analysis revealed a rapid uptake of IP6 by cells. The intracellular accumulation of IP6 was saturable at 0.5 h and it did not change with the prolongation of incubation up to 72 h.

  12. Determination of the amino acid requirements for a protein hinge in triosephosphate isomerase.

    OpenAIRE

    Sun, J.; Sampson, N. S.

    1998-01-01

    We have determined the sequence requirements for a protein hinge in triosephosphate isomerase. The codons encoding the hinge at the C-terminus of the active-site lid of triosephosphate isomerase were replaced with a genetic library of all possible 8,000 amino acid combinations. The most active of these 8,000 mutants were selected using in vivo complementation of a triosephosphate isomerase deficient strain of E. coli, DF502. Approximately 3% of the mutants complement DF502 with an activity th...

  13. Simultaneous determination of gallic acid and gentisic acid in organic anion transporter expressing cells by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Wang, Li; Halquist, Matthew S; Sweet, Douglas H

    2013-10-15

    In order to elucidate the role of organic anion transporters (OATs) in the renal elimination of gallic acid and gentisic acid, a new, rapid, and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous determination of gallic acid and gentisic acid in cell lysate, using Danshensu as the internal standard (IS). After a simple liquid-liquid extraction, the analytes were detected in negative ESI mode using selected reaction monitoring. The precursor-to-product ion transitions (m/z) were 169.0→125.0, 153.1→108.0, and 196.8→135.2 for gallic acid, gentisic acid, and the IS, respectively. Chromatographic separation was achieved on a C18 column using mobile phases consisting of water with 0.1% acetic acid (A) and acetonitrile with 0.05% formic acid. (B) The total run time was 3min and calibration curves were linear over the concentrations of 0.33-2400ng/mL for both compounds (r(2)>0.995). Good precision (between 3.11% and 14.1% RSD) and accuracy (between -12.7% and 11% bias) was observed for quality controls at concentrations of 0.33 (lower limit of quantification), 1, 50, and 2000ng/mL. The mean extraction recovery of gallic acid and gentisic acid was 80.7% and 83.5%, respectively. Results from post-column infusion and post-extraction methods indicated that the analytical method exhibited negligible matrix effects. Finally, this validated assay was successfully applied in a cellular uptake study to determine the intracellular concentrations of gallic acid and gentisic acid in OAT expressing cells.

  14. Simultaneous determination of prenylflavonoid and hop bitter acid in beer lee by HPLC-DAD-MS.

    Science.gov (United States)

    Kao, T H; Wu, G Y

    2013-11-15

    An HPLC-DAD-MS method with high accuracy and precision was developed for determination of prenylflavonoids and hop bitter acids in beer lee, a by-product from beer brewing process. Four prenylflavonoids and nine hop bitter acids can be simultaneously separated in 29 min using a Thermo HyPURITY C18 column in combination with diode array dectector and mass spectrometer with HPLC solvent gradient system of phosphoric acid aqueous solution at pH 1.6 and acetonitrile at a flow rate of 1.5 mL/min and detection wavelength at 314 nm. Beer lee is found to contain isoxanthohumol (36.2 μg/g), xanthohumol (29.6 μg/g), 8-prenylnaringenin (7.84 μg/g), 6-prenylnaringenin (19.2 μg/g), cohumulone (44.7 μg/g), humulone (123 μg/g), adhumulone (21.8 μg/g), colupulone (44.2 μg/g), lupulone (33.2 μg/g), and adlupulone (5.76 μg/g).

  15. High efficiency joint CZE determination of sugars and acids in vegetables and fruits.

    Science.gov (United States)

    Cebolla-Cornejo, Jaime; Valcárcel, Mercedes; Herrero-Martínez, José Manuel; Roselló, Salvador; Nuez, Fernando

    2012-08-01

    In this work, an improved CE method for the medium-throughput determination of main organic acids (oxalate, malate, citrate), the amino acid glutamate and the sugars fructose, glucose and sucrose in several food matrices is described. These compounds have been identified as key components in the taste intensity of fruit and vegetable crops. Using a running buffer with 20 mM 2,6-pyridine dicarboxylic acid pH 12.1 and 0.1% hexadimethrine bromide, replacing it every 5 h to avoid pH decrease, and optimizing capillary conditioning between runs with 58 mM SDS during 2 min at 20 psi, it is possible to effectively quantify these compounds while increasing medium throughput repeatability. This procedure resolves problems such as increases in migration time and reduction of resolution between problematic peaks (malate/citrate and fructose/glucose) detected in a previous method. The new procedure even considerably reduced time analysis down to 12 min. Under optimal conditions, a large number of injections (200) could be administered without any disturbances in the same capillary. The reliability of the proposed method was further investigated with several food matrix samples, including tomato, pepper, muskmelon, winter squash, and orange. This method is recommended for routine analysis of large number of samples typical of production quality systems or plant breeding programs.

  16. Simultaneous determination of niacin, niacinamide and nicotinuric acid in human plasma.

    Science.gov (United States)

    Pfuhl, P; Kärcher, U; Häring, N; Baumeister, A; Tawab, Mona Abdel; Schubert-Zsilavecz, M

    2005-01-04

    A sensitive, specific, accurate, and reproducible HPLC/MS-method for the simultaneous quantitative determination of niacin (NA) and its main metabolites niacinamide (NAM) and nicotinuric acid (NUR) in human plasma using chinolin-3-carboxylic acid as an internal standard was developed and validated according to international guidelines for method validation. All analytes and the internal standard were separated from acidified plasma by solid phase extraction. Afterwards the extracted samples were analyzed by HPLC/MS in the positive electrospray ionization mode (ESI) and selected ion monitoring (SIM). The total run time was 7 min between injections. The assay had a lower limit of quantification of 50.0 ng/mL for each analyte using 1 mL of plasma. The calibration curves were linear in the measured range between 50.0 and 750 ng/mL plasma. The overall precision and accuracy for all concentrations of quality controls and standards was better than 15%. No indications were found for possible instabilities of niacin, niacinamide and nicotinuric acid in plasma at -20 degrees C, in the extraction solvent or after repeated thawing/freezing cycles. In stabilities were observed in whole blood and in plasma at room temperature. The recovery of the extraction method ranged from 86 to 89% for the three analytes.

  17. Determination of acetylsalicylic acid in commercial tablets by SERS using silver nanoparticle-coated filter paper

    Science.gov (United States)

    Sallum, Loriz Francisco; Soares, Frederico Luis Felipe; Ardila, Jorge Armando; Carneiro, Renato Lajarim

    2014-12-01

    In this work, filter paper was used as a low cost substrate for silver nanoparticles in order to perform the detection and quantification of acetylsalicylic acid by SERS in a commercial tablet. The reaction conditions were 150 mM of ammonium hydroxide, 50 mM of silver nitrate, 500 mM of glucose, 12 min of the reaction time, 45 °C temperature, pretreatment with ammonium hydroxide and quantitative filter paper (1-2 μm). The average size of silver nanoparticles deposited on the paper substrate was 180 nm. Adsorption time of acetylsalicylic acid on the surface of the silver-coated filter paper was studied and an adsorption time of 80 min was used to build the analytical curve. It was possible to obtain a calibration curve with good precision with a coefficient of determination of 0.933. The method proposed in this work was capable to quantify acetylsalicylic acid in commercial tablets, at low concentration levels, with relative error of 2.06% compared to the HPLC. The preparation of filter paper coated with silver nanoparticles using Tollen's reagent presents several advantages such as low cost of synthesis, support and reagents; minimum amount of residuals, which are easily treated, despite the SERS spectroscopy presenting fast analysis, with low sample preparation and low amount of reactants as in HPLC analysis.

  18. Application of L-thiazolidine-4-carboxylic acid monolayer in electrochemical determination of copper(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    L-Thiazolidine-4-carboxylic acid monolayer was prepared on gold electrodes through the self-assembly approach.Such novel thioether-based monolayer could efficiently preconcentrate Cu2+,which provided a simple,stable and reproducible method for the determination of Cu2+.The modified electrodes were stable enough to be continuously used for one week(more than 30 times regeneration) with lower than 10% decrease in the response.They retained their initial activity for more than one month if used once a day.The calibration curve was linear for Cu2+ from 0.6 to 158.8 μg L?1 with a detection limit of 0.38 μg L?1.The relative standard deviation was 3.2% for a series of six successive measurements.The proposed method was applied in the determination of Cu2+ in mineral water and human hair samples.

  19. Sensitive determination of buformin using poly-aminobenzoic acid modified glassy carbon electrode

    Institute of Scientific and Technical Information of China (English)

    Gui-Ying Jin; Hui Li; Wan-Bang Xu

    2012-01-01

    Glassy carbon electrode, which is used to electrochemically determine the content of buformin, is modified with an electropolymerized film of p-aminobenzoic acid in pH 7.0 acetate buffer solution (ABS). The polymer showed an excellent electrocatalytic activity for the reduction of buformin. In pH 7.0 ABS, the cathodic peak current increased linearly over three concentration intervals of buformin, and the detection limit (S/N=3) was 2.0 ×10^9 g/mL. The method was successfully applied to directly determine buformin in tablets with standard addition recoveries of 95.8 102.5%. The proposed method is simple, cheap and highly efficient.

  20. High-performance liquid chromatographic separation of carminic acid, alpha- and beta-bixin, and alpha- and beta-norbixin, and the determination of carminic acid in foods.

    Science.gov (United States)

    Lancaster, F E; Lawrence, J F

    1996-05-03

    During a study of natural food colours, a simple and reliable high-performance liquid chromatography system was developed for use with cochineal and annato. An isocratic mobile phase, consisting of methanol and 6% aqueous acetic acid, resolved bixin and norbixin, while a gradient system was used to separate carminic acid and the annato compounds. The carminic acid contents of cochineal extract, carmine and carmine hydrosoluble were determined using an isocratic mobile phase (40:60, v/v). The detection limit for carminic acid in the various products was approximately 100 ng/g. Carminic acid was determined quantitatively in fruit beverages, yogurt and candies. It was demonstrated that, because of decomposition, carminic acid was not suitable for use in candies when manufacturing temperatures above 100 degrees C were required. Most membrane filters are not suitable for use with cochineal solutions, but a cellulose membrane filter did not adsorb carminic acid and was used successfully to remove impurities from water-based cochineal products and food extracts containing carminic acid.

  1. [Rapid determination of fatty acids in soybean oils by transmission reflection-near infrared spectroscopy].

    Science.gov (United States)

    Song, Tao; Zhang, Feng-ping; Liu, Yao-min; Wu, Zong-wen; Suo, You-rui

    2012-08-01

    In the present research, a novel method was established for determination of five fatty acids in soybean oil by transmission reflection-near infrared spectroscopy. The optimum conditions of mathematics model of five components (C16:0, C18:0, C18:1, C18:2 and C18:3) were studied, including the sample set selection, chemical value analysis, the detection methods and condition. Chemical value was analyzed by gas chromatography. One hundred fifty eight samples were selected, 138 for modeling set, 10 for testing set and 10 for unknown sample set. All samples were placed in sample pools and scanned by transmission reflection-near infrared spectrum after sonicleaning for 10 minute. The 1100-2500 nm spectral region was analyzed. The acquisition interval was 2 nm. Modified partial least square method was chosen for calibration mode creating. Result demonstrated that the 1-VR of five fatty acids between the reference value of the modeling sample set and the near infrared spectrum predictive value were 0.8839, 0.5830, 0.9001, 0.9776 and 0.9596, respectively. And the SECV of five fatty acids between the reference value of the modeling sample set and the near infrared spectrum predictive value were 0.42, 0.29, 0.83, 0.46 and 0.21, respectively. The standard error of the calibration (SECV) of five fatty acids between the reference value of testing sample set and the near infrared spectrum predictive value were 0.891, 0.790, 0.900, 0.976 and 0.942, respectively. It was proved that the near infrared spectrum predictive value was linear with chemical value and the mathematical model established for fatty acids of soybean oil was feasible. For validation, 10 unknown samples were selected for analysis by near infrared spectrum. The result demonstrated that the relative standard deviation between predict value and chemical value was less than 5.50%. That was to say that transmission reflection-near infrared spectroscopy had a good veracity in analysis of fatty acids of soybean oil.

  2. [Determination of phthalic acid esters in textiles by solid phase extraction-gas chromatography].

    Science.gov (United States)

    Niu, Zengyuan; Ye, Xiwen; Fang, Liping; Xue, Qiuhong; Sun, Zhongsong

    2006-09-01

    A method was established for the simultaneous determination of some phthalic acid esters, namely, dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPrP), dibutyl phthalate (DBP), diamyl phthalate (DAP), dihexyl phthalate (DHP), benzyln-butyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP), dicyclohexyl phthalate (DCHP), di-n-octyl phthalate (DNOP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP) in textiles by solid phase extraction (SPE) coupled with gas chromatography (GC). The phthalic acid esters in textiles were extracted by Soxhlet extraction with hexane, the extracts were then cleaned up and enriched by a strong anion exchange (SAX) SPE cartridge. The parameters affecting the purification efficiency of SPE cartridge, such as solvent conditioning, rinsing, and elution, were studied. Conditioning with 5 mL hexane and rinsing with 3 mL isooctane were proved to be the optimal conditions. Of the several solvent ratios (ethylacetate in hexane) used for selective elution of phthalic acid esters from the SAX SPE cartridge, the 15% (v/v) content for ethylacetate in hexane gave the best result. Under the optimized conditions, the recoveries of phthalic acid esters for spiked standards (n=7) were 86.3%-102.7%, and the relative standard deviations (RSDs) were less than 5%. In this method the detection limits for DMP, DEP, DPrP, DBP, DAP, BBP, DCHP, DEHP, DNOP were all below 1 mg/kg, and the detection limits for DINP and DIDP were 1.74 mg/kg and 1.55 mg/kg respectively. This SPE-GC method is sensitive, accurate and suitable for the analysis of phthalate environmental hormones in textiles.

  3. Determination of soluble solid content and acidity of loquats based on FT-NIR spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Xia-ping FU; Jian-ping LI; Ying ZHOU; Yi-bin YING; Li-juan XIE; Xiao-ying NIU; Zhan-ke YAN; Hai-yan YU

    2009-01-01

    The near infrared (NIR) spectroscopy technique has been applied in many fields because of its advantages of simple preparation,fast response,and non-destructiveness.We investigated the potential of NIR spectroscopy in diffuse reflectance mode for determining the soluble solid content (SSC) and acidity (pH) of intact loquats.Two cultivars of loquats (Dahongpao and Jiajiaozhong) harvested from two orchards (Tangxi and Chun'an,Zhejiang,China) were used for the measurement of NIR spectra between 800 and 2500 nm.A total of 400 loquats (100 samples of each cultivar from each orchard) were used in this study.Relationships between NIR spectra and SSC and acidity of ioquats were evaluated using partial least square (PLS) method.Spectra preprocessing options included the first and second derivatives,multiple scatter correction (MSC),and the standard normal variate (SNV).Three separate spectral windows identified as full NIR (800-2500 nm),short NIR (800~1100 nm),and long NIR (1100~2500 nm) were studied in factorial combination with the preprocessing options.The models gave relatively good predictions of the SSC of loquats,with root mean square error of prediction (RMSEP) values of 1.21,1.00,0.965,and 1.16 °Brix for Tangxi-Dahongpao,Tangxi-Jiajiaozhong,Chun'an-Dahongpao,and Chun'an-Jiajiaozhong,respectively.The acidity prediction was not satisfactory,with the RMSEP of 0.382,0.194,0.388,and 0.361 for the above four loquats,respectively.The results indicate that NIR diffuse reflectance spectroscopy can be used to predict the SSC and acidity of loquat fruit.

  4. Determination of muscimol and ibotenic acid in mushrooms of Amanitaceae by capillary electrophoresis.

    Science.gov (United States)

    Poliwoda, Anna; Zielińska, Katarzyna; Halama, Marek; Wieczorek, Piotr P

    2014-09-01

    In this study, the CZE method for rapid quantitative and qualitative determination of ibotenic acid and muscimol in Amanita mushrooms naturally grown in Poland was developed. The investigations included the species of A. muscaria, A. pantherina, and A. citrina, collected in southern region of Poland. The studied hallucinogenic compounds were effectively extracted with a mixture of methanol and 1 mM sodium phosphate buffer at pH 3 (1:1 v/v) using ultrasound-assisted procedure. The obtained extracts were separated and determined by CZE utilizing a 25 mM sodium phosphate running buffer adjusted to pH 3 with 5% content of acetonitrile v/v. The calibration curves for both analytes were linear in the range of 2.5-7000 μg/mL. The intraday and interday variations of quantitative data were 1.0 and 2.5% RSD, respectively. The recovery values of analyzed compounds were over 87%. The identities of ibotenic acid and muscimol were confirmed by UV spectra, migration time, and measurements after addition of external standard.

  5. Flow injection colorimetric method using acidic ceric nitrate as reagent for determination of ethanol.

    Science.gov (United States)

    Pinyou, Piyanut; Youngvises, Napaporn; Jakmunee, Jaroon

    2011-05-15

    Ceric ammonium nitrate has been used for qualitative analysis of ethanol. It forms an intensely colored unstable complex with alcohol. In this work, a simple flow injection (FI) colorimetric method was developed for the determination of ethanol, based on the reaction of ethanol with ceric ion in acidic medium to produce a red colored product having maximum absorption at 415 nm. Absorbance of this complex could be precisely measured in the FI system. A standard or sample solution was injected into a deionized water donor stream and flowed to a gas diffusion unit, where the ethanol diffused through a gas permeable membrane made of plumbing PTFE tape into an acceptor stream to react with ceric ammonium nitrate in nitric acid. Color intensity of the reddish product was monitored by a laboratory made LED based colorimeter and the signal was recorded on a computer as a peak. Peak height obtained was linearly proportional to the concentration of ethanol originally presented in the injected solution in the range of 0.1-10.0% (v/v) (r(2)=0.9993), with detection limit of 0.03% (v/v). With the use of gas diffusion membrane, most of the interferences could be eliminated. The proposed method was successfully applied for determination of ethanol in some alcoholic beverages, validating by gas chromatographic method.

  6. [Determination of ellagic acid, flavonoids and goshonoside-F5 in Rubi Fructus by HPLC].

    Science.gov (United States)

    He, Jian-Ming; Sun, Nan; Wu, Wen-Dan; Fan, Li-Jiao; Guo, Mei-Li

    2013-12-01

    High-performance liquid chromatographic coupled with variable wavelength detection (HPLC-VWD) has been developed for simultaneous determination of 5 analytes including ellagic acid, quercetin, kaempferol-3-O-beta-D-rutinoside, tiliroside and kaempferol, and high-performance liquid chromatographic with an evaporative light scattering detector (HPLC-ELSD) has been established to determine goshonoside-F5 in extract of Rubi Fructus. Chromatographic separations were carried out on an Agilent ZORBAX SB-C18 column (4.6 mm x 250 mm, 5.0 microm). All calibration curves of reference standards revealed good linearity (R2 > 0.999 5) within the concentration ranges tested. The method limits of detection ranged 0.297-90.144 ng and the method limits ofquantitation ranged 0.990-300.480 ng, respectively. Recoveries of 6 analytes were from 97.11% to 101.7%, with RSD less than 2.1%. The result shows that amounts of the 6 analytes in the samples from 16 localities were found to be different. The higher latitude of growing environment, the more ellagic acid in herb. The content of total flavonoids in sample from east localities were higher than that in middle and west localities, and the content of goshonoside-F5 in Bozhou, Anhui province was higher than others. This method was found to be simple, accurate, sensitive with good repeatability. Those results might serve as a sound foundation for further study, quality control and application of Rubi Fructus.

  7. Solid phase extraction and spectrophotometric determination of palladium with 2-(2-quinolylazo-5-diethylaminobenzoic acid

    Directory of Open Access Journals (Sweden)

    WEIZU YANG

    2006-07-01

    Full Text Available Asensitive, selective and rapid method for the determination of palladium based on the rapid reaction of palladium(II with 2-(2-quinolylazo-5-diethylaminobenzoic acid (QADEAB and the solid phase extraction of the Pd(II –QADEAB chelate with a reversed phase polymer-based C18 cartridge was developed. In the presence of 0.05 – 0. 5 mol/L of hydrochloric acid solution and cetyl trimethylammonium bromide (CTAB medium, QADEAB reacts with palladium(II to form a violet complex with a mole ratio 1:2 (palladium to QADEAB. The chelate was enriched by solid phase extraction with a reversed phase polymer-based C18 cartridge. An enrichment factor of 200 was obtained by elution of the chelate form the cartridge with the minimal amount of isopentyl alcohol. The molar absorptivity of the chelate in the isopentyl alcohol medium was 1.43 × 105 L mol-1 cm-1 at 628 nm. Beer’s law was obeyed in the range of 0.01 – 1.2 mg/mL. The relative standard deviation for eleven replicate samples at the 0.2 mg/L level was 2.18 %. The attained detection limit amounted to 0.02 mg/L in the original samples. This method was applied to the determination of palladium in environmental samples with good results.

  8. Determination of acrolein, ethanol, volatile acidity, and copper in different samples of sugarcane spirits

    Directory of Open Access Journals (Sweden)

    José Masson

    2012-09-01

    Full Text Available Seventy-one samples of sugarcane spirits from small and average size stills produced in the northern and southern Minas Gerais (Brazil were analyzed for acrolein using HPLC (High Performance Liquid Chromatography. Ethanol and copper concentrations and volatile acidity were also determined according to methods established by the Ministry of Agriculture, Livestock and Supply (MAPA. A total of 9.85% of the samples tested showed levels of acrolein above the legal limits, while the copper concentrations of 21.00% of the samples and the volatile acidity of 8.85% of the samples were higher than the limits established by the Brazilian legislation. The concentration of acrolein varied from 0 to 21.97 mg.100 mL-1 of ethanol. However, no significant difference at 5% of significance was observed between the samples produced in the northern and southern Minas Gerais. The method used for determination of acrolein in sugarcane spirits involved the formation of a derivative with 2,4-dinitrophenylhydrazine (2,4-DNPH and subsequent analysis by HPLC.

  9. Extraction and determination of ellagic acid contentin chestnut bark and fruit.

    Science.gov (United States)

    Vekiari, S A; Gordon, M H; García-Macías, P; Labrinea, H

    2008-10-15

    Chestnuts are an important economic resource in the chestnut growing regions, not only for the fruit, but also for the wood. The content of ellagic acid (EA), a naturally occurring inhibitor of carcinogenesis, was determined in chestnut fruits and bark. EA was extracted with methanol and free ellagic acid was determined by HPLC with UV detection, both in the crude extract and after hydrolysis. The concentration of EA was generally increased after hydrolysis due to the presence of ellagitannins in the crude extract. The concentration varied between 0.71 and 21.6mgg(-1) (d.w.) in un-hydrolyzed samples, and between 2.83 and 18.4mgg(-1) (d.w.) in hydrolyzed samples. In chestnut fruits, traces of EA were present in the seed, with higher concentrations in the pellicle and pericarp. However, all fruit tissues had lower concentrations of EA than had the bark. The concentration of EA in the hydrolyzed samples showed a non-linear correlation with the concentration in the unhydrolyzed extracts.

  10. Determination of sulfate in the wet-process of phosphoric acid by reverse flow injection

    Directory of Open Access Journals (Sweden)

    Wenhui Shi

    2014-01-01

    Full Text Available An improved method based on reverse flow injection is proposed for determining sulfate concentration in the wet-process of phosphoric acid (WPA. The effect of reagent composition, flow rate, temperature, acid concentration, length of the reaction coil, and linear response range on the flow system is discussed in detail. Optimal conditions are established for determining sulfate in the WPA samples. Baseline drift is avoided by a periodic washing step with EDTA in an alkaline medium. A linear response is observed within a range of 20 - 360 mg L-1, given by the equation A = 0.0020C (mg L-1 + 0.0300, R² = 0.9991. The detection limit of the proposed method for sulfate analysis is 3 mg L-1, and the relative standard deviation (n = 12 of sulfate absorbance peak is less than 1.60%. This method has a rate of up to 29 samples per hour, and the results compare well with those obtained with gravimetric method.

  11. A rapid method for determination of acid value in transformer oil by PPy modified electrode

    Institute of Scientific and Technical Information of China (English)

    熊英; 何德良; 冯勇; 周舟; 常新园; 刘芙蓉

    2014-01-01

    A polypyrrole-modified glassy carbon electrode (PPy/GC electrode) was prepared and its electrocatalytic behavior towards naphthoquinone in the presence of acid was characterized by linear sweep voltammetry (LSV). A well-defined new reduction peak appeared at a more positive potential than the original reduction peak. The new reduction peak current was linearly related to the acid value (AV) of oil. Based on it, a rapid electrochemical method for determining AV of transformer oil was developed using PPy/GC electrode. A working curve was obtained in the AV range of 0.01 to 0.40 mg(KOH)·g-1, with a sensitivity of 39.42μA0.5/(mg(KOH)·g-1) and the detection limit of 0.0014 mg(KOH)·g-1 (signal-to-noise ratio is 3, standard deviation is 2.247%). Moreover, the proposed method has been successfully applied to AV determination of several transformer oil samples with advantages of rapidness, high sensitivity and accuracy compared to the conventional method.

  12. A Modified Fluorimetric Method for Determination of Hydrogen Peroxide Using Homovanillic Acid Oxidation Principle

    Directory of Open Access Journals (Sweden)

    Biswaranjan Paital

    2014-01-01

    Full Text Available Hydrogen peroxide (H2O2 level in biological samples is used as an important index in various studies. Quantification of H2O2 level in tissue fractions in presence of H2O2 metabolizing enzymes may always provide an incorrect result. A modification is proposed for the spectrofluorimetric determination of H2O2 in homovanillic acid (HVA oxidation method. The modification was included to precipitate biological samples with cold trichloroacetic acid (TCA, 5% w/v followed by its neutralization with K2HPO4 before the fluorimetric estimation of H2O2 is performed. TCA was used to precipitate the protein portions contained in the tissue fractions. After employing the above modification, it was observed that H2O2 content in tissue samples was ≥2 fold higher than the content observed in unmodified method. Minimum 2 h incubation of samples in reaction mixture was required for completion of the reaction. The stability of the HVA dimer as reaction product was found to be >12 h. The method was validated by using known concentrations of H2O2 and catalase enzyme that quenches H2O2 as substrate. This method can be used efficiently to determine more accurate tissue H2O2 level without using internal standard and multiple samples can be processed at a time with additional low cost reagents such as TCA and K2HPO4.

  13. Rapid Determination of HAAs Formation Potential of the Reaction of Humic Acid with Chlorine or Chlorine Dioxide

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhi-liang; GE Yuan-xin; ZHANG Rong-hua; MA Hong-mei; HAO Jian-fu

    2007-01-01

    On the basis of gas chromatography(GC) coupled with a short capillary column and an electron capture detector(ECD), a simple and rapid method for the determination of five haloacetic acids(HAAs) in drinking water was developed by the optimization of derivation conditions and the modification of gas chromatographic program. HAAs formation potential(HAAFP) of the reaction of humic acid with chlorine was determined via this method. The major advantages of the method are the simplicity of chromatographic temperature program and the short run time of GC. Dichloroacetic acid(DCAA) and Trichloroacetic acid(TCAA), which were detected in the determination of HAAFP, were rapidly formed in the first 72 h of the reaction of humic acid with chlorine. HAAFP of the reaction of humic acid with chlorine increased with the increase in the concentrations of humic acid and chlorine. The average HAAFP of the reaction of humic acid with chlorine was 39.9 μg/mg TOC under the experimental conditions. When the concentration of humic acid was 4 mg/L, the concentration of HAAs, which were produced in the reaction of humic acid with chorine, may exceed MCL of 60 μg/L HAAs as the water quality standards for urban water supply of China and the first stage of US EPA disinfection/disinfection by-products(D/DBP) rule; when the concentration of humic acid was 2 mg/L, the concentration of HAAs may exceed MCL of 30 μg/L HAAs for the second stage of US EPA D/DBP rule. When humic acid was reacted with chlorine dioxide, only DCAA was detected with a maximum concentration of 3.3 μg/L at a humic acid content of 6 mg/L. It was demonstrated that the substitution of chlorine dioxide for chorine may entirely or partly control the formation of HAAs and effectively reduce the health risk associated with disinfected drinking water.

  14. Fast techniques for the evaluation of reservoirs capacity; Metodos de evaluacion rapida de capacidad de yacimentos

    Energy Technology Data Exchange (ETDEWEB)

    Flores Armenta, Magaly del Carmen [Gerencia de Proyectos Geotermoelectricos de la Comision Federal de Electricidad, Morelia (Mexico)

    1995-05-01

    Fast techniques for the evaluation of geothermal reservoirs allow us to have an approach of its electrical potential. Based on the laws of conservation of mass and energy, considering infinite permeability, this paper presents techniques for fast reservoir evaluation. These techniques let us calculate in a very practical way, the electric power that can be obtained from a geothermal field. These techniques can be an important tool to solve practical problems, and are useful during the preliminary development of geothermal sources. [Espanol] Los metodos de evaluacion rapida de yacimientos permiten estimar de manera aproximada la potencia electrica maxima y minima de los mismos. Se presentan tecnicas de evaluacion basadas en las leyes de conservacion de masa y energia, considerando permeabilidad infinita. Las tecnicas utilizadas pueden ser una herramienta importante para la solucion de problemas practicos y para la toma de decisiones en etapas de prefactibilidad.

  15. Determination of fruit characteristics, fatty acid profile and total antioxidant capacity ofMespilus germanica L. fruit

    Institute of Scientific and Technical Information of China (English)

    Hale Seilmi Canbay; Ersin Atay; Serdal Ot

    2015-01-01

    Objective:To determine fruit characteristics, fatty acid profile and total antioxidant capacitiy of first culturedMespilus germanica L. Methods: A total of15 fruits were taken randomly from four directions of adult trees.Then the physical and chemical properties of first cultured medlar fruit (Istanbul/Turkey) were measured by using refractometer, colorimeter, spectrophotometer and gas chromatograph mass spectrometer, respectivly. Results: In the fruit studied, the results showed that palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid and behenic acid were the most abundant fatty acids (FAs), and the main FA was palmitic acid [(35.35 ± 1.20)%]. The percentage of linoleic acid and stearic acid in this fruit oil were (29.10 ± 1.70)% and(8.53 ± 0.25)%, respectively. As a result of the analysis, the total antioxidant capacity of medlar fruit was (1.1 ± 0.2) mmol trolox equivalents/L. Conclusions: The present study has demonstrated the concentrations of FAs and the antioxidantive capacity of first cultured Istanbul medlar fruits by using many tested methods. It is proved that in our daily life, medlar fruit plays a significant role with its nutrition and health effect.

  16. Determination of phosphine: comparison of rates of desorption by purge-and-trap method and by sulfuric acid treatment.

    Science.gov (United States)

    Saeed, T; Abu-Tabanja, R

    1985-01-01

    Two methods were compared for quantitative determination of phosphine present on fumigated food and materials. The rate of desorption of PH3 by using a purge-and-trap method was shown to be much slower when compared with sulfuric acid treatment and was also simpler. Application of the modified sulfuric acid treatment for real samples is described.

  17. Determination of Amino Acids in Single Human Lymphocytes after On-capillary Derivatization by Capillary Zone Electrophoresis with Electrochemical Detection

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Amino acids in individual human lymphocytes were determined by capillary zone electrophoresis with electrochemical detection after on-capillary derivatization. In order to inject cells easily, a cell injector was designed. Four amino acids (serine, alanine, taurine, and glycine) in single human lymphocytes have been identified. Quantitation has been accomplished through the use of calibration curves.

  18. Determination of Medronic Acid and Its Related Substances by Reversed-Phase High-Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    An isocratic liquid chromatographic method with evaporative light scattering detection (ELSD) was developed for the determination of medronic acid and its related substance. Volatile pentylamine was used as ion-pairing agent. Separations were performend

  19. Using the Chiral Organophosphorus Derivatizing Agents for Determination of the Enantiomeric Composition of Chiral Carboxylic Acids by 31PNMR Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Chao CHE; Zhong Ning ZHANG; Gui Lan HUANG; Xin Xing WANG; Zhao Hai QIN

    2004-01-01

    The use of chiral organophosphorus derivatizing agents prepared in situ from chiral tartrate or chiral diamine for the 31PNMR determination of the enantiomeric composition of chiral carboxylic acids is described. The method is accurate, reliable and convenient.

  20. Simultaneous diffuse reflectance infrared determination of clavulanic acid and amoxicillin using multivariate calibration techniques.

    Science.gov (United States)

    Müller, Aline Lima Hermes; Picoloto, Rochele Sogari; Ferrão, Marco Flores; da Silva, Fabiana Ernestina Barcellos; Müller, Edson Irineu; Flores, Erico Marlon de Moraes

    2012-06-01

    A method for simultaneous determination of clavulanic acid (CA) and amoxicillin (AMO) in commercial tablets was developed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and multivariate calibration. Twenty-five samples (10 commercial and 15 synthetic) were used as a calibration set and 15 samples (10 commercial and 5 synthetic) were used for a prediction set. Calibration models were developed using partial least squares (PLS), interval PLS (iPLS), and synergy interval PLS (siPLS) algorithms. The best algorithm for CA determination was siPLS model with spectra divided in 30 intervals and combinations of 2 intervals. This model showed a root mean square error of prediction (RMSEP) of 5.1 mg g(-1). For AMO determination, the best siPLS model was obtained with spectra divided in 10 intervals and combinations of 4 intervals. This model showed a RMSEP of 22.3 mg g(-1). The proposed method was considered as a suitable for the simultaneous determination of CA and AMO in commercial pharmaceuticals products.

  1. Determination of fatty acids percentages and profile extracted from cuttlefish of Iranian coasts of Persian Gulf and Oman Sea

    Institute of Scientific and Technical Information of China (English)

    Yosief Ali Asadpour

    2014-01-01

    Objective: To determine the fatty acid profile extracted from cuttlefish of Persian Gulf and Oman Sea, including Ancistrocheirus, Enoploteuthidae, Cranchiidae, Ommastrephidae and Loliginidae. Methods:Oil was extracted by the Bligh and Dyer method. The fatty acid profile of the oil was determined by gas chromatography. Results:The results showed that (13±5)% of wet weight of cuttlefish is oil. The results also showed that cuttlefish oil has 29.40% saturated fatty acids and 23.70% single-band unsaturated fatty acids, and the total value of the unsaturated multiple-band is 40.20%, the contents of arachidonic acid 2.78%, linolenic acid 3.10%, linoleic acid 5.20%, docosahexaenoic acid 15.40%, and eicosapentaenoic acid 9.60% out of the total fatty acids of the same may be mentioned. Conclusions:The results of the current study described that cuttlefish is considered for the first time as the new and rich source of omega-3 and omega-6.

  2. Is the fatty acid composition of Daphnia galeata determined by the fatty acid composition of the ingested diet?

    NARCIS (Netherlands)

    Weers, P.M.M.; Siewertsen, K.; Gulati, R.D.

    1997-01-01

    1. The fatty acid (FA) composition of Daphnia galeata and their algal food was analysed and showed many similarities, however, some significant differences were also found in the relative abundance of the FA C16:4 omega 3 and docosahexaenoic acid (DHA). Their relative abundances were much lower in d

  3. On the determination of minor phenolic acids of virgin olive oil by RP-HPLC

    Directory of Open Access Journals (Sweden)

    Tsimidou, M.

    1996-06-01

    Full Text Available The objective of this study was the detection and determination of four minor phenolic acids present in the polar fraction of olive oil. Gallic, homovanillic, caffeic and ferulic acids, were separated on RP-HPLC and detected by using three different systems. Detection limits were determined for the four compounds. Variable wavelength UV detectors were found to be more suitable than diode array for quantitative information. However, diode array was required for qualitative information for unknown components present in olive oil. For the determination of sensitive phenolic compouds present in minor amounts the use of a more sensitive system, such as the electrochemical detector, was necessary.

    El objetivo de este estudio fue la detección y determinación de cuatro ácidos fenólicos minoritarios presentes en la fracción polar del aceite de oliva. Los ácidos gálico, homovanílico, cafeico y ferúlico fueron separados mediante RP-HPLC y detectados usando tres sistemas diferentes. Se determinaron los límites de detección para los cuatro componentes. Se encontró que los detectores UV a longitud de onda variable son más apropiados que los detectores de batería de diodos para la información cuantitativa. Sin embargo, el detector de batería de diodo fue necesario para la información cualitativa de componentes desconocidos en el aceite de oliva. Para la determinación de compuestos fenólicos sensibles, presentes en cantidades minoritarias, fue necesario el uso de un sistema más sensible, como es el detector electroquímico.

  4. Rapid fluorometric determination of perfluorooctanoic acid by its quenching effect on the fluorescence of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qi; Huang, Aizhen; Wang, Nan, E-mail: nwang@hust.edu.cn; Zheng, Guan; Zhu, Lihua

    2015-05-15

    Analysis of perfluorooctanoic acid (PFOA) usually requires a combination of high-performance liquid chromatography and mass spectrometry, which is expensive and time-consuming. In the present work, water-soluble CdS quantum dots (QDs) were employed to develop a simple and rapid fluorometric method for the determination of PFOA. Strongly fluorescent CdS QDs were prepared by using 3-mercaptopropionic acid (MPA) as a stabilizer. It was observed that PFOA strongly quenched the fluorescence emission of the MPA-CdS QDs because PFOA promotes the aggregation of MPA-CdS QDs through a fluorine–fluorine affinity interaction. Under optimum conditions, the fluorescence intensity of MPA-CdS QDs was observed to decrease linearly with an increase in the concentration of PFOA from 0.5 to 40 μmol L{sup −1}, with a limit of detection of 0.3 μmol L{sup −1}. This new method was successfully implemented for the analysis of PFOA-spiked textile samples, with recoveries ranging from 95% to 113%. - Highlights: • PFOA significantly quenched the fluorescence emission of quantum dots (QDs). • A rapid and simple fluorescence sensor was proposed for determining PFOA by QDs. • PFOA determination could be completed within approximately 10 min. • The developed method had a working range of 0.5 to 40 μmol L{sup −1} and a detection limit of 0.3 μmol L{sup −1}.

  5. Electrocatalytic oxidation and voltammetric determination of ciprofloxacin employing poly(alizarin red)/graphene composite film in the presence of ascorbic acid, uric acid and dopamine.

    Science.gov (United States)

    Zhang, Xin; Wei, Youli; Ding, Yaping

    2014-07-04

    A glassy carbon electrode modified with poly(alizarin red)/electrodeposited graphene (PAR/EGR) composite film was prepared and applied to detect ciprofloxacin (CPFX) in the presence of ascorbic, uric acid and dopamine. The morphology and interface property of PAR/EGR films were examined by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrocatalytic oxidation of CPFX on AR/EGR was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The linearity ranged from 4 × 10(-8) to 1.2 × 10(-4) M with a detection limit (S/N=3) of 0.01 μM. The modified electrode could be applied to the individual determination of CPFX as well as the simultaneous determination of CPFX, ascorbic acid, uric acid and dopamine. This method proved to be a simple, selective and rapid way to determine CPFX in pharmaceutical preparation and biological media.

  6. Osservazioni sul principio di legalità come idea e come metodo nell’esperienza giuridica della Chiesa

    Directory of Open Access Journals (Sweden)

    Beatrice Serra

    2012-10-01

    Full Text Available Contributo sottoposto a valutazioneSOMMARIO: 1. Introduzione - 2. – La struttura essenziale del concetto di legalità e la sua realizzazione radicale nel diritto della Chiesa. - 3. L’idea di legalità come “regola che sta prima” nel ius commune e la sua coesistenza con un approccio empirico, essenzialmente giurisprudenziale e dottrinale, di costruzione del diritto. Il principio di legalità come metodo di produzione del diritto nel pensiero giuridico moderno- 4. Il legame storico-concettuale fra il principio di legalità e i Codici moderni - 5. Il Codex iuris canonici del 1917 e il principio di legalità come metodo di costruzione del ius ecclesiae in funzione della certezza del diritto - 6. (segueUlteriori riflessi della prima codificazione canonica sul principio di legalità.:

  7. Determination of 4-Chloroindole-3-Acetic Acid Methyl Ester in Lathyrus Vicia and Pisum by Gas Chromatography - Mass Spectrometry

    DEFF Research Database (Denmark)

    Engvild, Kjeld Christensen; Egsgaard, Helge; Larsen, Elfinn

    1980-01-01

    4-Chloroindole-3-acetic acid methyl ester was identified unequivocally in Lathyrus latifolius L., Vicia faba L. and Pisum sativum L. by thin layer chromatography, gas chromatography and mass spectrometry. The gas chromatographic system was able to separate underivatized chloroindole-3-acetic acid...... methyl ester isomers. The quantitative determination of 4-chloroindole-3-acetic acid methyl ester in immature seeds of these three species was performed by gas chromatography – mass spectrometry using deuterium labelled 4-chloro-indole-3-acetic acid methyl ester as an internal standard. P. sativum...

  8. Determination of Nitric Acid in Aqueous Solution of Uranium and Plutonium Purification Cycle by Near Infrared Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LI; Ding-ming; WANG; Lin; ZHANG; Li-hua; GONG; Yan-ping; MU; Ling; WU; Ji-zong

    2012-01-01

    <正>The concentration of nitric acid interfered with the distribution of uranium and plutonium in nuclear fuel reprocessing process. So, in the reprocessing process control analysis, the determination of the free acid plays an important role. Traditional laboratory analytical method of free acid needs large size sample and is time-consuming. Hence, development of fast analytical method for free acid has important significance for the reprocessing process control analysis. Near-infrared spectroscopy (NIRS) has been proved to be a powerful analytical tool and used in various fields, it’s seldom, however, used in spent

  9. Determining Total Phenolics, Anthocyanin Content and Ascorbic Acid Content in Some Plum Genotypes Grown in Ardahan Ecological Conditions

    Directory of Open Access Journals (Sweden)

    Z. T. ABACI

    2014-06-01

    Full Text Available In this study, total phenol content, total anthocyanin content, brix, pH, titrable acidity and total ascorbic acid content in the five plum genotypes cultivated in Ardahan City are determined and sustenance of the plums are revealed. Total phenol content was determined with folin-ciocalteu’s method, total anthocyanin content was determined with pH differential method and total ascorbic acid was determined with 2,6-dichlorophenolindophenol method.It is detected that the genotype with the highest brix content (%13.9 and lowest acidity (%0.98 is cancur, the genotype with the lowest brix content (%11 and highest acidity (%2.06 is wild plum, the genotype with the highest content of total anthocyanin, total phenolic substance and ascorbic acid is the wild plum and the genotype with the least content of these is the water plum. As a result of the study, it is revealed that the plum fruit has high levels of phenolic substance, anthocyanin and ascorbic acid content, so it has a high sustenance.

  10. PH metric method for the determination of nicotinic acid in plasma.

    Science.gov (United States)

    Gravesen, J

    1977-04-01

    The acidimetric method for the determination of nicotinic acid (NA) using Lactobacillus plantarum ATCC 8014 (Lactobacillus arabinosus 17-5) has been simplified and thus made less time consuming, and the sensitivity has been increased fivefold by replacement of the titration by a pH determination. As the regression of the decrease in pH on the amount of NA was found linear within a range of 1 to 4 ng of NA per ml, the calculations were performed according to the slope-ratio principle. The NA concentration of plasma was determined with a coefficient of variation of 5 to 7%, which rose to about 10% at low NA concentrations. Assays of fasting plasma samples from 13 hyperlipidemic male patients showed a group mean NA concentration of 80 +/- 55 ng/ml (mean +/- 2 standard deviation), before treatment, and 705 +/- 544 ng/ml (mean +/- 2 standard deviation) during therapy with sustained release NA preparations, of which a single dose, ingested during steady-state conditions, doubled or tripled the plasma concentration within 1 to 3 h.

  11. Fourier Transform Infrared (FTIR) Spectroscopy as a Utilitarian Tool for the Routine Determination of Acidity in Ester-Based Oils.

    Science.gov (United States)

    Meng, Xianghe; Li, Lei; Ye, Qin; van de Voort, Frederik

    2015-09-23

    A primary Fourier transform infrared (FTIR) method capable of determining acidity in ester-based oils is described and evaluated. Absolute free fatty acid (%FFA) and acid value (AV) calibrations were devised by spiking oleic acid into a refined, acid-free oil and measuring ν COO(-) at ∼ 1569 and ν phenolate(-) at ∼ 1588 cm(-1), respectively, in the second-derivative differential spectra. The FTIR acidity predictions were compared to the AOCS titrimetric method using acid mixtures as well as acid containing used vendor oils of undefined makeup and provenance, using two spectroscopically divergent reference oils as AC0. Relative to the AOCS reference method, the FTIR procedure was found to be both more accurate (± 0.107 vs ± 0.122) and reproducible (± 0.025 vs ± 0.077) in determining %FFA and similar in predicting AV. The FTIR phenolate method overcomes a variety of limitations of earlier FTIR-based methods, being particularly simple and well suited to routine, semiautomated acidity analysis of ester-based oils using a basic FTIR spectrometer.

  12. Why is sulfuric acid a much stronger acid than ethanol? Determination of the contributions by inductive/field effects and electron-delocalization effects.

    Science.gov (United States)

    Lynch, Kevin; Maloney, Adam; Sowell, Austin; Wang, Changwei; Mo, Yirong; Karty, Joel M

    2015-01-07

    Two different and complementary computational methods were used to determine the contributions by inductive/field effects and by electron-delocalization effects toward the enhancement of the gas-phase deprotonation enthalpy of sulfuric acid over ethanol. Our alkylogue extrapolation method employed density functional theory calculations to determine the deprotonation enthalpy of the alkylogues of sulfuric acid, HOSO2-(CH2CH2)n-OH, and of ethanol, CH3CH2-(CH2CH2)n-OH. The inductive/field effect imparted by the HOSO2 group for a given alkylogue of sulfuric acid was taken to be the difference in deprotonation enthalpy between corresponding (i.e., same n) alkylogues of sulfuric acid and ethanol. Extrapolating the inductive/field effect values for the n = 1-6 alkylogues, we obtained a value of 51.0 ± 6.4 kcal mol(-1) for the inductive/field effect for n = 0, sulfuric acid, leaving 15.4 kcal mol(-1) as the contribution by electron-delocalization effects. Our block-localized wavefunction method was employed to calculate the deprotonation enthalpies of sulfuric acid and ethanol using the electron-localized acid and anion species, which were compared to the values calculated using the electron-delocalized species. The contribution from electron delocalization was thus determined to be 18.2 kcal mol(-1), which is similar to the value obtained from the alkylogue extrapolation method. The two methods, therefore, unambiguously agree that both inductive/field effects and electron-delocalization effects have significant contributions to the enhancement of the deprotonation enthalpy of sulfuric acid compared with ethanol, and that the inductive/field effects are the dominant contributor.

  13. Spectrophotometric Determination of Gemifloxacin Mesylate, Moxifloxacin Hydrochloride, and Enrofloxacin in Pharmaceutical Formulations Using Acid Dyes

    Directory of Open Access Journals (Sweden)

    Ayman A. Gouda

    2014-01-01

    Full Text Available Simple, rapid, and extractive spectrophotometric methods were developed for the determination of some fluoroquinolones antibiotics: gemifloxacin mesylate (GMF, moxifloxacin hydrochloride (MXF, and enrofloxacin (ENF in pure forms and pharmaceutical formulations. These methods are based on the formation of ion-pair complexes between the basic drugs and acid dyes, namely, bromocresol green (BCG, bromocresol purple (BCP, bromophenol blue (BPB, bromothymol blue (BTB, and methyl orange (MO in acidic buffer solutions. The formed complexes were extracted with chloroform and measured at 420, 408, 416, 415, and 422 nm for BCG, BCP, BPB, BTB, and MO, respectively, for GMF; at 410, 415, 416, and 420 nm for BCP, BTB, BPB, and MO, respectively, for MXF; and at 419 and 414 nm for BCG and BTB, respectively, in case of ENF. The analytical parameters and their effects are investigated. Beer’s law was obeyed in the ranges 1.0–30, 1.0–20, and 2.0–24 μg mL−1 for GMF, MXF, and ENF, respectively. The proposed methods have been applied successfully for the analysis of the studied drugs in pure forms and pharmaceutical formulations. Statistical comparison of the results with the reference methods showed excellent agreement and indicated no significant difference in accuracy and precision.

  14. Determination of dissolved naphthenic acids in natural waters by using negative-ion electrospray mass spectrometry.

    Science.gov (United States)

    Headley, John V; Peru, Kerry M; McMartin, Dena W; Winkler, Marcus

    2002-01-01

    Naphthenic acids (NAs) have been implicated as some of the most toxic substances in oil sands leachates and identified as priority substances impacting on aquatic environments. As a group of compounds, NAs are not well characterized and comprise a large group of saturated aliphatic and alicyclic carboxylic acids found in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils). Described is an analytical method using negative-ion electrospray ionization mass spectrometry (ES/MS) of extracts. Preconcentration was achieved by using a solid-phase extraction procedure utilizing a crosslinked polystyrene-based polymer with acetonitrile elution. Recovery of the Fluka Chemicals NA mixture was highly pH-dependent, with 100% recovery at pH 3.0, but only 66 and 51% recoveries at pHs 7 and 9, respectively. The dissolved phase of the NA was very dependent on sample pH. It is thus critical to measure the pH and determine the appropriate mass profiles to identify NAs in natural waters. The ES/MS analytical procedure proved to be a fast and sensitive method for the recovery and detection of NAs in natural waters, with a detection limit of 0.01 mg/L.

  15. Iron oxide nanoparticles modified with oleic acid: Vibrational and phase determination

    Science.gov (United States)

    Soares, Paula P.; Barcellos, Geórgia S.; Petzhold, Cesar L.; Lavayen, Vladimir

    2016-12-01

    A simple path methodology to detect the phase composition of iron oxide nanoparticles modified with oleic acid based on vibrational spectroscopy is present here and applied on three different nanoparticles prepared by co-precipitation method. Firstly, the phase composition, magnetite, maghemite, and hematite, is determined using a reference intensity ratio methodology on X-ray diffraction pattern. Also, the size of each sample was calculated by Scherrer equation. Scanning, transmission electron microscopy, microanalysis and electron diffraction show a core magnetite particles size of around 10 nm for all particles. Based on lattice vibrations, we find a concentration of around 80% of magnetite and a hematite phase lower than 5%. Whereas, the magnetite composition from X-ray diffraction shows 76%. We also investigate the metal-organic interaction and disorder degree of organic molecule conformation by infrared and Raman spectroscopy analysis. Hematite lattice vibrations show more alterations as it interacts with the organic acid. Finally, magnetic measurements at room temperature of the modified particles, suggest a superparamagnetic behavior and high saturation magnetization.

  16. Determination of hepatic uridine 5'-diphosphoglucuronic acid concentration by conjugation with diethylstilbestrol.

    Science.gov (United States)

    Watkins, J B; Klaassen, C D

    1982-03-01

    A sensitive and reliable assay for uridine 5'-diphosphoglucuronic acid (UDPGA) was developed that involved conjugation of diethylstilbestrol (DES) in vitro. This conjugation reaction is solely dependent upon UDPGA concentration. The assay uses 0.13 M Tris-HCl, pH 7.4, 6.7 mM MgCl2, 0.05% Brig 58, 0.25 mg guinea pig liver microsomal protein, 0.13 mM 3H-DES (0.2 microCi/ml), and 200 microliters of boiled 10% liver homogenate in a total volume of 0.5 ml. After a 60-min incubation at 37 degrees C, unconjugated DES is extracted into 5 ml of chloroform and the residual metabolized 3H-DES in the aqueous phase is determined by liquid scintillation spectrometry. After addition of beta-glucuronidase to the aqueous phase, about 90% of the radioactivity could be extracted into chloroform, demonstrating the DES-glucuronic acid is the primary metabolite. Thus, this method easily permits quantitation of UDPGA in rat liver in the 1-10 nmol range.

  17. Determination of methacrylic acid in food simulants by pyrolytic butylation-gas chromatography.

    Science.gov (United States)

    Huang, Zhongping; Qiu, Ruofeng; Liu, Tingfei; Huang, Yilei; Zhu, Zuoyi; Wang, Lili

    2016-07-08

    An on-line pyrolytic butylation approach was proposed to determine methacrylic acid (MA) in food simulants by gas chromatography (GC) without an expensive pyrolyzer. MA in food simulants was converted into butyl methacrylate in the presence of tetrabutylammonium hydroxide (TBAH) without any pretreatment at 330°C in the injection-port, contributing to high GC signal response. The derivatizing conditions for the proposed method were optimized, namely the injection-port temperature, type and amount of the organic alkaline used for derivatization. A series of standard solutions of MA in the range of 1.0-50mg/kg were analyzed with correlation coefficient r≥0.9975. The limits of detection (LODs) were less than 0.15mg/kg for MA in four matrix simulants (distilled water, 3%w/v acetic acid, 10%v/v ethanol, and isooctane). Relative standard deviations (RSDs) for retention time, peak height and peak area were all less than 3.88%. The technique was successfully applied to the analysis of MA migrating from plastic cup samples, with recoveries of added MA in the range of 96.5-123.0%. Direct injection of the simulants into the GC system after migration tests, without any pretreatment step, makes the developed method of great value for rapid screening analysis of samples in bulks.

  18. Selectivity and affinity determinants for ligand binding to the aromatic amino acid hydroxylases.

    Science.gov (United States)

    Teigen, Knut; McKinney, Jeffrey Alan; Haavik, Jan; Martínez, Aurora

    2007-01-01

    Hydroxylation of the aromatic amino acids phenylalanine, tyrosine and tryptophan is carried out by a family of non-heme iron and tetrahydrobiopterin (BH4) dependent enzymes, i.e. the aromatic amino acid hydroxylases (AAHs). The reactions catalyzed by these enzymes are important for biomedicine and their mutant forms in humans are associated with phenylketonuria (phenylalanine hydroxylase), Parkinson's disease and DOPA-responsive dystonia (tyrosine hydroxylase), and possibly neuropsychiatric and gastrointestinal disorders (tryptophan hydroxylase 1 and 2). We attempt to rationalize current knowledge about substrate and inhibitor specificity based on the three-dimensional structures of the enzymes and their complexes with substrates, cofactors and inhibitors. In addition, further insights on the selectivity and affinity determinants for ligand binding in the AAHs were obtained from molecular interaction field (MIF) analysis. We applied this computational structural approach to a rational analysis of structural differences at the active sites of the enzymes, a strategy that can help in the design of novel selective ligands for each AAH.

  19. Lipid nutritional value of legumes: Evaluation of different extraction methods and determination of fatty acid composition.

    Science.gov (United States)

    Caprioli, Giovanni; Giusti, Federica; Ballini, Roberto; Sagratini, Gianni; Vila-Donat, Pilar; Vittori, Sauro; Fiorini, Dennis

    2016-02-01

    This study sought to contribute to the assessment of the nutritional properties of legumes by determining the fatty acid (FA) composition of 29 legume samples after the evaluation of nine extraction methods. The Folch method and liquid-solid extraction with hexane/isopropanol or with hexane/acetone were investigated, as was the effect of previous hydration of samples. Soxhlet extractions were also evaluated with different solvent mixtures. Results on FA composition using the hexane/isopropanol extraction method were the same in terms of FA composition of the Folch method, but the extraction yield was only around 20-40% of that of the Folch method preceded by hydration. Some types of legumes showed particularly interesting values for the ratio of polyunsaturated fatty acids (PUFAs) n-6/n-3, such as lentils, with the value of 4.0, and Azuki beans, at 3.2. In lentils, the PUFAs% ranged from 42.0% to 57.4%, while in Azuki beans it was 57.5%.

  20. Determination of tartaric acid in wines by FIA with tubular tartrate-selective electrodes.

    Science.gov (United States)

    Sales, M G; Amaral, C E; Matos, C M

    2001-03-01

    A flow injection analysis (FIA) system comprising a tartrate-(TAT) selective electrode has been developed for determination of tartaric acid in wines. Several electrodes constructed for this purpose had a PVC membrane with a complex of quaternary ammonium and TAT as anion exchanger, a phenol derivative as additive, and a more or less polar mediator solvent. Characterization of the electrodes showed behavior was best for membranes with o-nitrophenyl octyl ether as solvent. On injection of 500 microL into a phosphate buffer carrier (pH = 3.1; ionic strength 10(-2) mol/L) flowing at 3 mL/min, the slope was 58.06 +/- 0.6 with a lower limit of linear range of 5.0 x 10(-4) mol/L TAT and R2 = 0.9989. The interference of several species, e.g. chloride, bromide, iodide, nitrate, gallic acid, tannin, sucrose, glucose, fructose, acetate, and citrate, was evaluated in terms of potentiometric selectivity coefficients. The Hofmeister series was followed for inorganic species and the most interfering organic ion was citrate. When red and white wines were analyzed and the results compared with those from an independent method they were found to be accurate, with relative standard deviations below 5.0%.

  1. Determination of aristolochic acids by high-performance liquid chromatography with fluorescence detection.

    Science.gov (United States)

    Wang, Yinan; Chan, Wan

    2014-06-25

    Nephrotoxic and carcinogenic aristolochic acids (AAs) are naturally occurring nitrophenanthrene carboxylic acids in the herbal genus Aristolochia. The misuse of AA-containing herbs in preparing slimming drugs has caused hundred of cases of kidney disease in Belgium women in a slimming regime in the early 1990s. Accumulating evidence also suggested that prolong dietary intake of AA-contaminated food is one of the major causes to the Balkan endemic nephropathy that was first observed in the late 1950s. Therefore, analytical methods of high sensitivity are extremely important for safeguarding human exposure to AA-containing herbal medicines, herbal remedies, and food composites. In this paper, we describe the development of a new high-performance liquid chromatography coupled fluorescence detector (HPLC-FLD) method for the sensitive determination of AAs. The method makes use of a novel cysteine-induced denitration reaction that "turns on" the fluorescence of AAs for fluorometric detections. Our results showed that the combination of cysteine-induced denitration and HPLC-FLD analysis allows for sensitive quantification of AA-I and AA-II at detection limits of 27.1 and 25.4 ng/g, respectively. The method was validated and has been successfully applied in quantifying AAs in Chinese herbal medicines.

  2. EXTRACTION AND QUANTITATIVE DETERMINATION OF ASCORBIC ACID FROM BANANA PEEL MUSA ACUMINATA ‘KEPOK’

    Directory of Open Access Journals (Sweden)

    Khairul Anwar Mohamad Said

    2016-04-01

    Full Text Available This paper discusses the extraction of an antioxidant compound, which is ascorbic acid or vitamin C, from a banana peel using an ultrasound-assisted extraction (UAE method. The type of banana used was Musa acuminata also known as “PisangKepok” in Malaysia. The investigation includes the effect of solvent/solid ratio (4.5, 5 g and 10  ml/g, sonication time (15, 30 and 45 mins and temperature variation (30 , 45  and 60oC on the extraction of ascorbic acid compounds from the banana peel to determine the best or optimum condition of the operation. Out of all extract samples analyzed by redox titration method using iodine solution, it was found that the highest yield was 0.04939 ± 0.00080 mg that resulted from an extraction at 30oC for 15 mins with 5 ml/g solvent-to-solute ratio.KEYWORDS:  Musa acuminata; ultrasound-assisted extraction; vitamin C; redox titration

  3. Determination of chitosan with a modified acid hydrolysis and HPLC method.

    Science.gov (United States)

    Li, Bo; Zhang, Jiali; Bu, Fen; Xia, Wenshui

    2013-01-25

    Acid hydrolysis and subsequent quantification of glucosamine (GlcN) are widely used for chitosan quantification. Degradation of GlcN during chitosan hydrolysis was the main reason for the decrease of recovery, which made the method improper for the quantification of chitosan. Ten milligram of chitosan hydrolyzed with 10 mL mixed acid solution of HCl-H₃PO₄ (75:25 in molar ratio) showed the highest recovery, significantly higher than HCl hydrolysis. Further study revealed that the optimum conditions involved the hydrolysis with HCl-H₃PO₄ (4.5:1.5M) for 24 h at 110 °C. The hydrolysate was neutralized and derived with 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl) before HPLC quantification. The optimum ratio of FMOC-Cl:GlcN was 53:1, with excess FMOC-Cl induced by the high ionic strength of the solution. This quantification procedure was then validated and proved to be specific, with good linearity, accuracy, and precision, making it well-suited for the determination of chitosan.

  4. Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Huiying Wang

    2013-11-01

    Full Text Available A versatile strategy for electrochemical determination of glycoalkaloids (GAs was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA modified glassy carbon electrode. PBA reacts with α-solanine and α-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 μM to 28 μM and the detection limit was 0.3 μM. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors.

  5. Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode

    Science.gov (United States)

    Wang, Huiying; Liu, Mingyue; Hu, Xinxi; Li, Mei; Xiong, Xingyao

    2013-01-01

    A versatile strategy for electrochemical determination of glycoalkaloids (GAs) was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA) modified glassy carbon electrode. PBA reacts with α-solanine and α-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 μM to 28 μM and the detection limit was 0.3 μM. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors. PMID:24287539

  6. Amperometric Determination of Indole-3-acetic Acid Based on Platinum Nanowires and Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Ruo Zhong WANG; Lang Tao XIAO; Ming Hui YANG; Jun Hui DING; Feng Li QU; Guo Li SHEN

    2006-01-01

    Platinum nanowire (PtNW) can be grown by electrodeposition in polycarbonate membrane, with the average diameter of the nanowires about 250 nm. The PtNW and multiwalled carbon nanotubes (CNT) are then dispersed into chitosan (CHIT) solution. The resulting PtNW-CNT-CHIT material brings new capabilities for electrochemical devices by using the synergistic action of the electrocatalytic activity of PtNW and CNT. By dropping the PtNW-CNT-CHIT film onto the glassy carbon (GC) electrode surface, and after evaporationan amperometric sensor for the determination of indole-3-acetic acid (IAA) was developed. The oxidation current of IAA increased significantly at the PtNW-CNT-CHIT film coated GC electrode,in contrast to that at the CNT-CHIT modified GC. The linear response of the sensor is from 50ng/ml to 50 μg/ml with a detection limit of 25 ng/mL.

  7. Identification of novel genetic determinants of erythrocyte membrane fatty acid composition among Greenlanders

    DEFF Research Database (Denmark)

    Andersen, Mette Korre; Jørsboe, Emil; Sandholt, Camilla Helene

    2016-01-01

    .181), p = 2.8x10-4). In conclusion, we have identified novel genetic determinants of FA composition in phospholipids in erythrocyte membranes, and have shown examples of links between genetic variants associated with altered FA membrane levels and changes in metabolic traits.......Fatty acids (FAs) are involved in cellular processes important for normal body function, and perturbation of FA balance has been linked to metabolic disturbances, including type 2 diabetes. An individual's level of FAs is affected by diet, lifestyle, and genetic variation. We aimed to improve...... the understanding of the mechanisms and pathways involved in regulation of FA tissue levels, by identifying genetic loci associated with inter-individual differences in erythrocyte membrane FA levels. We assessed the levels of 22 FAs in the phospholipid fraction of erythrocyte membranes from 2,626 Greenlanders...

  8. Spectrometric determination of clinically relevant fatty acids in the blood serum

    Science.gov (United States)

    Kalinin, A. V.; Krasheninnikov, V. N.; Sviridov, A. P.; Titov, V. N.

    2016-12-01

    The content of fatty acid (FA) triglycerides in food and biological media is predicting traditionally using gas and liquid chromatographic methods. Named techniques aren't available for clinical labs due to their complexity. So, our objective was to develop the method and apparatus for rapid assay of a few clinically important FA as the saturated palmitic, mono unsaturated oleic and others in serum using near infrared spectrometer. As a result, the applicability of the FT spectrometer in the wavelength range of 0.9 -1.8 μ to analyze these FA in serum without sample preparation was confirmed. Besides, measurement specifications were determined and a correlations of the absorption spectra and contents of total triglycerides and cholesterol, palmitic, oleic, linoleic and arachidonic FA in serum were established

  9. Determination of hydroxyl radicals with salicylic acid in aqueous nitrate and nitrite solutions

    Institute of Scientific and Technical Information of China (English)

    YANG Xi; ZHAN Man-jun; KONG Ling-ren; WANG Lian-sheng

    2004-01-01

    The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicylic acid was employed as an innovative molecular probe of hydroxyl radical(OH) generated in aqueous nitrate and nitrite solutions through photochemical reactions. Kinetic studies showed that the steady-state concentrations of OH in aqueous NO3-(10 mmol/L, pH = 5) and NO2- (10 mmol/L, pH = 5) solutions under ultraviolet irradiation were at a same magnitude, 10-15 mol/L. Apparent quantum yields of OH at 313 nm were measured as 0.011 and 0.07 for NO3- and NO2- respectively, all comparable to the results of previous studies.

  10. Determination of organic acids evolution during apple cider fermentation using an improved HPLC analysis method

    NARCIS (Netherlands)

    Zhang, H.; Zhou, F.; Ji, B.; Nout, M.J.R.; Fang, Q.; Zhang, Z.

    2008-01-01

    An efficient method for analyzing ten organic acids in food, namely citric, pyruvic, malic, lactic, succinic, formic, acetic, adipic, propionic and butyric acids, using HPLC was developed. Boric acid was added into the mobile phase to separate lactic and succinic acids, and a post-column buffer solu

  11. Determination of plasma lactic acid concentration and specific activity using high-performance liquid chromatography.

    Science.gov (United States)

    Bleiberg, B; Steinberg, J J; Katz, S D; Wexler, J; LeJemtel, T

    1991-08-23

    Assessment of lactate metabolism is of particular interest during exercise and in disease states such as diabetes, shock, and absorptive abnormalities of short-chain fatty acids by the colon. We describe an analytical method that introduces radio-active tracers and high-performance liquid chromatography (HPLC) to simultaneously analyze concentrations and specific activities (SAs) of plasma lactate. The HPLC conditions included separation on a reversed-phase column (octadecylsilane) and an isocratic buffer (30% acetonitrile in water). [3H]Acetate served as an internal standard. Lactate and acetate were extracted from plasma samples with diethyl ether following a pH adjustment to less than 1.0 and back-extracted into a hydrophilic phase with sodium carbonate (2 mM, pH greater than 10.0). Lactate is detected in the ultraviolet range (242 and 320 nm) by derivatization with alpha-bromoacetophenone. Control plasma samples were studied after an overnight fast for precision and analytical recovery. Calibration curves were linear in the range 0.18-6.0 mM (r = 0.92). The precision was 3% and the analytical recovery was 87%. The detection limit of the method was 36 pmol. Determination of lactate metabolism was performed in a patient with chronic congestive heart failure who was administered primed-continuous L-[U-14C]lactate (10 microCi bolus and 0.3 microCi/min continuously) during a 60-min rest period. Mean arterial lactate concentration and SA were 1.69 +/- 0.2 mM and 253.8 +/- 22 dpm/mumol, respectively. Systemic lactate turnover was 25.65 mumol/kg per min. Lactic acid systemic turnover, organ uptake and release rates can be accurately determined by isocratic HPLC.

  12. Identification of Novel Genetic Determinants of Erythrocyte Membrane Fatty Acid Composition among Greenlanders.

    Directory of Open Access Journals (Sweden)

    Mette Korre Andersen

    2016-06-01

    Full Text Available Fatty acids (FAs are involved in cellular processes important for normal body function, and perturbation of FA balance has been linked to metabolic disturbances, including type 2 diabetes. An individual's level of FAs is affected by diet, lifestyle, and genetic variation. We aimed to improve the understanding of the mechanisms and pathways involved in regulation of FA tissue levels, by identifying genetic loci associated with inter-individual differences in erythrocyte membrane FA levels. We assessed the levels of 22 FAs in the phospholipid fraction of erythrocyte membranes from 2,626 Greenlanders in relation to single nucleotide polymorphisms genotyped on the MetaboChip or imputed. We identified six independent association signals. Novel loci were identified on chromosomes 5 and 11 showing strongest association with oleic acid (rs76430747 in ACSL6, beta (SE: -0.386% (0.034, p = 1.8x10-28 and docosahexaenoic acid (rs6035106 in DTD1, 0.137% (0.025, p = 6.4x10-8, respectively. For a missense variant (rs80356779 in CPT1A, we identified a number of novel FA associations, the strongest with 11-eicosenoic acid (0.473% (0.035, p = 2.6x10-38, and for variants in FADS2 (rs174570, LPCAT3 (rs2110073, and CERS4 (rs11881630 we replicated known FA associations. Moreover, we observed metabolic implications of the ACSL6 (rs76430747 and CPT1A (rs80356779 variants, which both were associated with altered HbA1c (0.051% (0.013, p = 5.6x10-6 and -0.034% (0.016, p = 3.1x10-4, respectively. The latter variant was also associated with reduced insulin resistance (HOMA-IR, -0.193 (0.050, p = 3.8x10-6, as well as measures of smaller body size, including weight (-2.676 kg (0.523, p = 2.4x10-7, lean mass (-1.200 kg (0.271, p = 1.7x10-6, height (-0.966 cm (0.230, p = 2.0x10-5, and BMI (-0.638 kg/m2 (0.181, p = 2.8x10-4. In conclusion, we have identified novel genetic determinants of FA composition in phospholipids in erythrocyte membranes, and have shown examples of links

  13. [Determination of organic acids and inorganic anions by gradient ion chromatography].

    Science.gov (United States)

    Liu, Z; Liu, K; Shen, D; Song, Q; Mou, S; Feng, Y

    1997-07-01

    The chromatographic conditions for separation and detection of organic acids and inorganic anions by gradient ion chromatography with suppressed conductivity detection were studied. The optimized gradient programs were established. Ion chromatography were performed with a DX-100 chromatograph (DIONEX). The separation column is IonPac-AS11. Compared with NaHCO3/Na2CO3 and Na2B4O7, NaOH was the optimal eluent. The effect of organic modifier was also studied. Among methanol, 2-propanol and acetonitrile, methanol can make ion pairs such as malate and succinate, malonate and tartrate gaining baseline resolution. By using ion exchange separation, Cl-, NO3-, malate, succinate, malonate, tartrate, SO4(2-), oxalate were eluted between 5 mmol/L NaOH-16% CH3OH and 10 mmol/L NaOH-16% CH3OH in 25 min. A mobile phase composed of 30 mmol/L NaOH, 50% CH3OH and D.I. water was chosen to elute two groups of organic acids and inorganic anions: (1) quinate, formate, Cl-, malate, malonate, oxalate, citrate, isocitrate, aconitate; (2) lactate, Cl-, SO4(2-), tartrate, PO4(3-), citrate, isocitrate, aconitate. The detection limits (S/N = 3) were 0.1625 (quinate), 0.0691 (formate), 0.0115 (Cl-), 0.0886 (malate), 0.0591 (malonate), 0.0263 (oxalate), 0.1147 (citrate), 0.2017 (isocitrate), 0.3656 (cis-aconitate), 0.1045 (trans-aconitate), 0.1950 (lactate), 0.0729 (tartrate), 0.0224 (SO4(2-)) and 0.0692 (PO4(3-)) mg/L. The relative standard deviations were lower than 11.9% (n = 7) and the correlation coefficients ranged from 0.9212 for Cl- to 0.9999 for formate. The method was applied to determine the organic acids and inorganic anions of beverages and citric acids fermenting-medium. The results were satisfactory.

  14. RP-HPLC Determination and Pharmacokinetic Comparison of Cinnamic Acid in Rat Plasma After Administration of Di-Gu-Pi Decoction and Pure Cinnamic Acid

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A sensitive, simple, and accurate method was developed for the determination and pharmacokinetic comparison of cinnamic acid in rat plasma after the administration of a Traditional Chinese Medicinal preparation, Di-Gu-Pi decoction, and pure cinnamic acid using RP-HPLC. Di-Gu-Pi was extracted with 5% aqueous sodium bicarbonate, which was followed by purification with ion exchange column chromatography. The plasma samples taken from rats were deproteinized with methanol. The reversed-phase(HPLC) system with a Diamonsil C18 column and methanol-acetonitrile-water (8∶32∶60, volume ratio) (adjusted to pH=3.0 with glacial acetic acid) as the mobile phase was employed for the separation of cinnamic acid in the plasma samples. The detection was set at 272 nm and 3-(p-fluorophenyl)-2-propenoic acid was chosen as the internal standard. The calibration curve was linear in a range from 0.10 to 25.0 μg/mL (R2=0.9988, n=9). The precision was 3.42%-10.10%; the between-day precision was 2.84%-8.91%; the accuracy was -1.51%-1.26%; the mean recovery was 99.9%. The method was found to be sensitive, simple, accurate and appropriate for the determination of cinnamic acid.

  15. Mercaptopropionic acid-capped CdTe quantum dots as fluorescence probe for the determination of salicylic acid in pharmaceutical products.

    Science.gov (United States)

    Bunkoed, Opas; Kanatharana, Proespichaya

    2015-11-01

    Mercaptopropionic acid (MPA)-capped cadmium telluride (CdTe) quantum dot (QDs) fluorescent probes were synthesized in aqueous solution and used for the determination of salicylic acid. The interaction between the MPA-capped CdTe QDs and salicylic acid was studied using fluorescence spectroscopy and some parameters that could modify the fluorescence were investigated to optimize the measurements. Under optimum conditions, the quenched fluorescence intensity of MPA-capped CdTe QDs was linearly proportional to the concentration of salicylic acid in the range of 0.5-40 µg mL(-1) with a coefficient of determination of 0.998, and the limit of detection was 0.15 µg mL(-1). The method was successfully applied to the determination of salicylic acid in pharmaceutical products, and satisfactory results were obtained that were in agreement with both the high pressure liquid chromatography (HPLC) method and the claimed values. The recovery of the method was in the range 99 ± 3% to 105 ± 9%. The proposed method is simple, rapid, cost effective, highly sensitivity and eminently suitable for the quality control of pharmaceutical preparation. The possible mechanisms for the observed quenching reaction was also discussed.

  16. Polymorphisms in the fatty acid desaturase genes and diet are important determinants of infant docosahexaenoic acid status

    DEFF Research Database (Denmark)

    Lauritzen, L.; Harsløf, L.; Larsen, L.H.;

    2013-01-01

    Tissue docosahexaenoic acid (DHA) accretion in early infancy is supported by DHA in breast-milk and may thus decrease once complementary feeding takes over. Endogenous synthesis of DHA from alphalinolenic acid is low and polymorphisms in the genes that encodes the fatty acid desaturases (FADS) has...... been shown to have little effect on DHA-status in adults. It is unclear to what extent endogenous DHA-synthesis contributes to infant DHAstatus. We aim to investigate the role of diet and FADS-polymorphisms on DHA-status at 9 months and 3 years. Methods: This cross-sectional study with Danish infants...... use data from two prospective studies (EFiON and the SKOTcohort). We measured erythrocyte (RBC) DHA-status at 9 months (n=409) and 3 years (n=176) and genotyped 4 FADS tagSNPs, rs3834458, rs1535, rs174575 and rs174448 (n=401)....

  17. Evaluation of spectrophotometric and HPLC methods for shikimic acid determination in plants: models in glyphosate-resistant and -susceptible crops.

    Science.gov (United States)

    Zelaya, Ian A; Anderson, Jennifer A H; Owen, Micheal D K; Landes, Reid D

    2011-03-23

    Endogenous shikimic acid determinations are routinely used to assess the efficacy of glyphosate in plants. Numerous analytical methods exist in the public domain for the detection of shikimic acid, yet the most commonly cited comprise spectrophotometric and high-pressure liquid chromatography (HPLC) methods. This paper compares an HPLC and two spectrophotometric methods (Spec 1 and Spec 2) and assesses the effectiveness in the detection of shikimic acid in the tissues of glyphosate-treated plants. Furthermore, the study evaluates the versatility of two acid-based shikimic acid extraction methods and assesses the longevity of plant extract samples under different storage conditions. Finally, Spec 1 and Spec 2 are further characterized with respect to (1) the capacity to discern between shikimic acid and chemically related alicyclic hydroxy acids, (2) the stability of the chromophore (t1/2), (3) the detection limits, and (4) the cost and simplicity of undertaking the analytical procedure. Overall, spectrophotometric methods were more cost-effective and simpler to execute yet provided a narrower detection limit compared to HPLC. All three methods were specific to shikimic acid and detected the compound in the tissues of glyphosate-susceptible crops, increasing exponentially in concentration within 24 h of glyphosate application and plateauing at approximately 72 h. Spec 1 estimated more shikimic acid in identical plant extract samples compared to Spec 2 and, likewise, HPLC detection was more effective than spectrophotometric determinations. Given the unprecedented global adoption of glyphosate-resistant crops and concomitant use of glyphosate, an effective and accurate assessment of glyphosate efficacy is important. Endogenous shikimic acid determinations are instrumental in corroborating the efficacy of glyphosate and therefore have numerous applications in herbicide research and related areas of science as well as resolving many commercial issues as a consequence of

  18. Simultaneous determination of niflumic acid and its prodrug, talniflumate in human plasma by high performance liquid chromatography.

    Science.gov (United States)

    Jang, Dong-Jin; Park, Jeong-Sook; Ko, Hye-Ran; Jee, Jun-Pil; Kim, Jin-Ki; Kim, Sung Tae; Kim, Chong-Kook

    2005-01-01

    A high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of niflumic acid and its prodrug, talniflumate, in human plasma. Niflumic acid and talniflumate were eluted isocratically with methanol-water (73:27, v/v, adjusted to pH 3.5 by acetic acid) at a fl ow rate of 1 mL/min. Indomethacin was used as an internal standard. Signals were monitored by an UV detector at 288 nm. Retention times of indomethacin, niflumic acid and talniflumate were 5.9, 7.2 and 13.5 min, respectively. Calibration plots were linear over the range 50-5000 ng/mL for niflumic acid and 100-5000 ng/mL for talniflumate. The limits of quantitation were 50 ng/mL for niflumic acid and 100 ng/mL for talniflumate. The intra- and inter-day relative standard deviations (RSD) of niflumic acid and talniflumate were less than 10% and the accuracies were higher than 90%. This method is rapid, sensitive and reproducible for the determination of niflumic acid and talniflumate in human plasma.

  19. Determination of salvianolic acid C in rat plasma using liquid chromatography-mass spectrometry and its application to pharmacokinetic study.

    Science.gov (United States)

    Song, Junke; Zhang, Wen; Sun, Jialin; Zhang, Xue; Xu, Xiaona; Zhang, Li; Feng, Zhangying; Du, Guanhua

    2016-03-01

    A sensitive and reliable LC-ESI-MS method for the determination of salvianolic acid C in rat plasma has been developed and validated. Plasma samples were prepared by liquid-liquid extraction with ethyl acetate and separated on a Zorbax SB-C18 column (3.5 µm, 2.1 × 100 mm) at a flow rate of 0.3 mL/min using acetonitrile-water as mobile phase. The detection was carried out by a single quadrupole mass spectrometer with electrospray ionization source and selected ion monitoring mode. Linearity was obtained for salvianolic acid C ranging from 5 to 1000 ng/mL. The intra- and inter-day precisions (RSD, %) didn't exceed 9.96%, and the accuracy (RE, %) were all within ±3.64%. The average recoveries of the analyte and internal standard were >89.13%. Salvianolic acid C was proved to be stable during all sample storage, preparation and analytic procedures. The validated method was successfully applied to pharmacokinetic study after oral and intravenous administration of salvianolic acid C to rats. The absolute oral bioavailability of salvianolic acid C was 0.29 ± 0.05%. This method was further applied to simultaneous determination of salvianolic acid A, salvianolic acid B and salvianolic acid C in rat plasma and showed good practicability.

  20. Simultaneous determination and pharmacokinetic study of four phenolic acids in rat plasma using UFLC-MS/MS after intravenous administration of salvianolic acid for injection.

    Science.gov (United States)

    Xie, Xiuman; Miao, Jingzhuo; Sun, Wanyang; Huang, Jingyi; Li, Dongxiang; Li, Shuming; Tong, Ling; Sun, Guoxiang

    2017-02-05

    A simple, sensitive and selective ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method was established for simultaneous determination and pharmacokinetic study of rosmarinic acid (RA), salvianolic acid D (Sal D), lithospermic acid (LA) and salvianolic acid B (Sal B) in rat plasma after intravenous administration of salvianolic acid for injection (SAFI). Three doses of administration, containing 14, 28 and 56mg/kg, were investigated in this study. Plasma samples were pretreated using protein precipitation (PP) with pre-cooled acetonitrile. Chromatographic separation was achieved on a CORTECS™ UPLC C18 column (1.6μm, 2.1×100mm) with a mobile phase composed of 0.1% formic acid aqueous (V/V) and 0.1% formic acid acetonitrile (V/V). Analytes were detected using electrospray ionization (ESI) source in negative ionization mode and quantified in multiple reaction monitoring (MRM) mode. The validated method is stable and reliable. No significant difference of half lives (t1/2) of four analytes at three doses was observed. Area under the curve (AUC0-∞) and peak concentration (Cmax) of the four analytes demonstrated a linear increase in across the doses with the linear correlation r of each analyte at three doses were greater than 0.95. It indicated that the pharmacokinetic behavior of SAFI is positively related to dose at the range of 14-56mg/kg.

  1. Quantitative Determination of Fatty Acids in Marine Fish and Shellfish from Warm Water of Straits of Malacca for Nutraceutical Purposes

    Directory of Open Access Journals (Sweden)

    Nurnadia Abd Aziz

    2013-01-01

    Full Text Available This study was conducted to quantitatively determine the fatty acid contents of 20 species of marine fish and four species of shellfish from Straits of Malacca. Most samples contained fairly high amounts of polyunsaturated fatty acids (PUFAs, especially alpha-linolenic acid (ALA, C18:3 n3, eicosapentaenoic acid (EPA, C20:5 n3, and docosahexaenoic acid (DHA, C22:6 n3. Longtail shad, yellowstripe scad, and moonfish contained significantly higher (P<0.05 amounts of eicosapentaenoic acid (EPA, docosahexaenoic acid (DHA, and alpha-linolenic acid (ALA, respectively. Meanwhile, fringescale sardinella, malabar red snapper, black pomfret, Japanese threadfin bream, giant seaperch, and sixbar grouper showed considerably high content (537.2–944.1 mg/100g wet sample of desirable omega-3 fatty acids. The polyunsaturated-fatty-acids/saturated-fatty-acids (P/S ratios for most samples were higher than that of Menhaden oil (P/S=0.58, a recommended PUFA supplement which may help to lower blood pressure. Yellowstripe scad (highest DHA, ω-3/ω-6=6.4, P/S=1.7, moonfish (highest ALA, ω-3/ω-6=1.9, P/S=1.0, and longtail shad (highest EPA, ω-3/ω-6=0.8, P/S=0.4 were the samples with an outstandingly desirable overall composition of fatty acids. Overall, the marine fish and shellfish from the area contained good composition of fatty acids which offer health benefits and may be used for nutraceutical purposes in the future.

  2. Factors affecting variations in the detailed fatty acid profile of Mediterranean buffalo milk determined by 2-dimensional gas chromatography.

    Science.gov (United States)

    Pegolo, S; Stocco, G; Mele, M; Schiavon, S; Bittante, G; Cecchinato, A

    2017-04-01

    Buffalo milk is the world's second most widely produced milk, and increasing attention is being paid to its composition, particularly the fatty acid profile. The objectives of the present study were (1) to characterize the fatty acid composition of Mediterranean buffalo milk, and (2) to investigate potential sources of variation in the buffalo milk fatty acid profile. We determined the profile of 69 fatty acid traits in 272 individual samples of Mediterranean buffalo milk using gas chromatography. In total, 51 individual fatty acids were identified: 24 saturated fatty acids, 13 monounsaturated fatty acids, and 14 polyunsaturated fatty acids. The major individual fatty acids in buffalo milk were in the order 16:0, 18:1 cis-9, 14:0, and 18:0. Saturated fatty acids were the predominant fraction in buffalo milk fat (70.49%); monounsaturated and polyunsaturated fatty acids were at 25.95 and 3.54%, respectively. Adopting a classification based on carbon-chain length, we found that medium-chain fatty acids (11-16 carbons) represented the greater part (53.7%) of the fatty acid fraction of buffalo milk, whereas long-chain fatty acids (17-24 carbons) and short-chain fatty acids (4-10 carbons) accounted for 32.73 and 9.72%, respectively. The n-3 and n-6 fatty acids were 0.46 and 1.77%, respectively. The main conjugated linoleic acid, rumenic acid, represented 0.45% of total milk fatty acids. Herd/test date and stage of lactation were confirmed as important sources of variation in the fatty acid profile of buffalo milk. The percentages of short-chain and medium-chain fatty acids in buffalo milk increased in early lactation (+0.6 and +3.5%, respectively), whereas long-chain fatty acids decreased (-4.2%). The only exception to this pattern was butyric acid, which linearly decreased from the beginning of lactation, confirmation that its synthesis is independent of malonyl-CoA. These results seem to suggest that in early lactation the mobilization of energy reserves may have less

  3. A New Method for Determination of Naphthenic Acids in Crude Oil

    Institute of Scientific and Technical Information of China (English)

    Lü Zhenbo; Zhai Yuchun; Zhao Shanlin; Zhuang Lihong

    2004-01-01

    The petroleum acids in crude oil were separated by extraction with column chromatogram and anion exchange resin. The separation effect and the related composition and structure of petroleum acids were obtained by using IR (Infra-Red) spectra techniques. The separated petroleum acids can under special conditions react with methanol to form corresponding esters, which can be analyzed by CI (chemical ionization)-MS (mass spectrometry). The characteristic ion peaks m/z (M+15)+ of naphthenic acid esters combined with z-series formula CnH2n+zO2 of naphthenic acids can be used to classify naphthenic acids into fatty acids, mono-cyclic, bi-cyclic, tri-cyclic, and higher polycyclic acids. The analytical results can give the molecular weight and the carbon number distribution of petroleum acids contained in crude oil. The results of study indicate that this method is simple, rapid and easy in operation.

  4. Identification and determination of erucic acid in infant formula using Gas Chromatography

    Directory of Open Access Journals (Sweden)

    Sabzevari O

    2007-05-01

    Full Text Available Background: Infant formula, depending on the source, contains various fatty acids, which may possess important nutritional and biological value for infants. The presence of some of these fatty acids in infant formula, however, can be harmful and toxic for the infant. In this regard, more attention has been paid to erucic acid since its accumulation in myocardial tissues may cause damage to the heart. Therefore, a limit has been set by the Codex Alimentarius for the presence of erucic acid in infant formula (less than 1% of total fatty acids. The purpose of the present study is to investigate amount of erucic acid present in three infant formulas used predominantly in Iran. Methods: Gas chromatography (GC is a valuable method applied for the separation of fatty acids, including erucic acid, from oils and oily food. Three brands of infant formulas, namely Humana, Biomil and Multi, were analyzed by GC using a wall coated open tubular (WCOT fused silica column and flame ionization detector (FID. Heneicosanoic acid was employed as an internal standard. Results: The findings showed that Humana and Biomil infant formula samples contained 0.06% and 0.002% erucic acid (from total fatty acids, respectively, while no erucic acid was detected in the Multi infant formula samples. Conclusion: The amount of erucic acid in the studied infant formulas was far below the Codex limit of 1% total fatty acids.

  5. "Determination of mycophenolic acid in human plasma by high-performance liquid chromatography"

    Directory of Open Access Journals (Sweden)

    "Mehdi Ahadi Barzoki

    2005-05-01

    Full Text Available A simple, sensitive and reproducible HPLC method is presented for determination of mycophenolic acid(MPA in human plasma. Samples were prepared after precipitation of the plasma protein by addition of acetonitrile and naproxen was used as internal standard (I.S.. Separation was performed by reversedphase HPLC, using a Hamilton PRP-C18 Column, 51% acetonitrile and 49% potassium phosphate buffer (20 mM at pH 3.0 as mobile phase, flow rate of 1.0 ml/min, and UV detection at 215 nm. MPA and I.S. had retention times of 7.5 and 11.35 min, respectively. The method showed an acceptable linearity in the range of 0.1µg/ml-40µg/ml with r2 of .9992. The concentration of 0.1µg/ml was determined as quantification limit. Mean absolute recovery was 94.8%. The mean intra- and inter-day reproducibility of method was 4.6 and 11.4% respectively.

  6. Flow-injection determination of isoniazid using sodium dichloroisocyanurate- and trichloroisocyanuric acid-luminol chemiluminescence systems.

    Science.gov (United States)

    Safavi, A; Karimi, M A; Hormozi Nezhad, M R

    2004-06-01

    A chemiluminescent (CL) method for the determination of isoniazid is described. The method is based on the CL generated during the oxidation of luminol by sodium dichloroisocyanurate (SDCC) and trichloroisocyanuric acid (TCCA) in alkaline medium. It was found that isoniazid greatly enhances this CL intensity when present in the luminol solution. Based on this observation, a new flow-injection CL method for the determination of isoniazid has been proposed in this paper. The detection limits were 2 and 3 ng ml(-1) isoniazid for the SDCC-luminol and TCCA-luminol CL systems, respectively. The relative CL intensity was linear with the isoniazid concentration in the range of 4-100 and 100-200 ng ml(-1) for the SDCC-luminol CL system, and 6-200 and 200-1000 ng ml(-1) for the TCCA-luminol CL system. The results obtained for the assay of pharmaceutical preparations compared well with those obtained by the official methods and demonstrated good accuracy and precision.

  7. Determination of catecholamines by ion chromatography coupled to acidic potassium permanganate chemiluminescence detection

    Institute of Scientific and Technical Information of China (English)

    Hong Wei Wu; Mei Lan Chen; Dan Shou; Yan Zhu

    2012-01-01

    A simple,fast,sensitive,highly selective and eco-friendly analytical method for the determination of catecholamines in human urine by ion chromatography (IC) with chemiluminescence (CL) detection was described in this paper.Using 12 mmoi/L H2SO4 without any organic additive as eluent,three catecholamines including epinephrine (EP),norepinephrine (NE) and dopamine (DA)were well separated on a cation-exchange column.The CL detection was based on the reaction of analytes with acidic potassium permanganate in the presence of formaldehyde as an enhancer.The absence of methanol and acetonitrile in eluent made the proposed method more sensitive and eco-friendly.Under the optimal conditions,the linear range of the proposed method was in the range of 0.02-0.5 μg/mL.The limit of detection (LOD) was in the range of 0.6 and 5.1 μg/L.The relative standard deviations (RSD) for 0.1 μg/mL mixed standard solution were in the range of 0.8-1.9% (n =11).The method has been applied to the determination of catecholamines in human urine successfully.Excellent spiked recoveries were achieved for catecholamines ranged from 91.2% to 112.7%.

  8. Electrochemical determination of ascorbic acid at p-phenylenediamine film-holes modified glassy carbon electrode

    Directory of Open Access Journals (Sweden)

    Olana Bikila Nagasa

    2015-01-01

    Full Text Available In this work the determination of ascorbic acid (AA at glassy carbon electrode (GCE modified with a perforated film produced by reduction of diazonium generated in situ from p-phenylenediamine (PD is reported. Holes were intentionally created in the modifier film by stripping a pre-deposited gold nanoparticles. The modified electrodes were electrochemically characterized by common redox probes: hydroquinone, ferrocyanide and hexamineruthenium(III. The cyclic voltammetric and amperometric response of AA using the modified electrodes was compared with that of bare GCE. The bare GCE showed a linear response to AA in the concentration range of 5 mM to 45 mM with detection limit of 1.656 mM and the modified GCE showed a linear response to AA in the concentration range of 5 μM to 45 μM with detection limit of 0.123 μM. The effect of potential intereferents on amperometric signal of AA at the modified GCE was examined and found to be minimal. The inter-electrode reproducibility, stability, and accuracy were determined. The modified electrode showed excellent inter-electrode reproducibility, accuracy and stability. The modified electrode reported is a promising candidate for use in electroanalysis of AA.

  9. Linear sweep polarographic determination of nucleic acids using acridine orange as a bioprobe

    Directory of Open Access Journals (Sweden)

    WEI SUN

    2007-11-01

    Full Text Available The interaction of acridine orange (AO with double-stranded (ds DNA in aqueous solution was investigated by linear sweep polarography (LSP on a dropping mercury working electrode (DME. In pH 2.5 Britton–Robinson (B–R buffer solution, AO had a sensitive linear sweep polarographic reductive peak at –0.89 V (vs. SCE, which could be greatly inhibited by the addition of dsDNA, with a positive shift of the peak potential. Based on the decrease of the reductive peak current, a new quantitative electrochemical determination method for dsDNA was developed with a linear range of 2.0−20.0 mg l-1 and the linear regression equation: ΔIp” (nA = 111.90 C (mg l-1+125.32 (n = 9, γ = 0.997. The influences of commonly co-existing substances, such as metal ions, amino acid, etc., on the determination were also investigated. The method is sensitive, rapid and simple with good selectivity. The new proposed method was further applied to the detection of RNA and three synthetic samples containing dsDNA with satisfactory results. The binding number and the equilibrium constant between dsDNA and AO were calculated by an electrochemical method.

  10. Glassy carbon electrodes modified with gelatin functionalized reduced graphene oxide nanosheet for determination of gallic acid

    Indian Academy of Sciences (India)

    Fereshteh Chekin; Samira Bagheri; Sharifah Bee Abd Hamid

    2015-12-01

    A simple approach for the preparation of gelatin functionalized reduced graphene oxide nanosheet (Gel-RGONS) by chemical reduction of graphene oxide (GO) using gelatin as both reducing agent and stabilizing agent in an aqueous solution was developed. The morphology and structure of the Gel-RGONS were examined by X-ray diffraction, transmission electron microscopy, ultraviolet–visible spectroscopy and Raman spectroscopy. Gelatin acted as a functionalizing reagent to guarantee good dispersibility and stability of the r in distilled water. Moreover, a new electrochemical sensor was developed based on Gel-RGONS modified glassy carbon electrode (Gel-RGONS/GCE). Gel-r exhibits excellent electrocatalytic activity to gallic acid (GA) oxidation. The experimental conditions such as pH, adsorption time and scan rate were optimized for the determination of GA. Under optimum conditions, the sensor responded linearly to GA in the concentration of 1.0 × 10−6 to 1.1 × 10−4 M with detection limit of 4.7 × 10−7 M at 3 using linear sweep voltammetry (LSV). The method has been successfully applied to the determination of GA in sample of black tea.

  11. [Determination of glyphosate and aminomethylphosphonic acid in rice using liquid chromatography-tandem mass spectrometry].

    Science.gov (United States)

    Cao, Zhaoyun; Mou, Renxiang; Chen, Mingxue

    2010-08-01

    A method was developed for the determination of glyphosate (GLY) and aminomethylphosphonic acid (AMPA) in rice using liquid chromatography tandem mass spectrometry (LC-MS/MS). The sample was extracted with water followed by a simple cleanup with a C18 solid phase extraction (SPE) cartridge, and then GLY and AMPA were derivatized using 9-fluorenylmethoxycarbonyl (FMOC-Cl) in borate buffer. The derivatives of GLY and AMPA were separated on a C18 column with gradient elution with the mobile phase of acetonitrile and 5 mmol/L ammonium acetate (pH 9), and finally detected with negative ion electrospray ionization-mass spectrometry (ESI-MS) in multiple reaction monitoring (MRM) mode. The results showed that the linearities of GLY and AMPA were in the concentration range of 0.000 50 to 1.0 mg/L with the correlation coefficients of 0.999 7 and 0.999 9, respectively. The mean spiked recoveries of GLY and AMPA at 3 spiked levels ranged from 72.5% to 113.6% with the relative standard deviations (RSD, n = 5) of 3.8% - 16.2%. The limits of detection were 2.0 and 3.0 microg/kg for GLY and AMPA, respectively. This method is rapid, sensitive, and suitable for simultaneous determination of GLY and AMPA in rice.

  12. Determination of modification degree in BDDE-modified hyaluronic acid hydrogel by SEC/MS.

    Science.gov (United States)

    Yang, Biao; Guo, Xueping; Zang, Hengchang; Liu, Jianjian

    2015-10-20

    Determination of modification degree in BDDE-modified hyaluronic acid (HA) hydrogel is of particular interest. In this paper, three crosslinking parameters (degree of total modification, t-MOD; degree of cross-link modification, c-MOD; degree of pendent modification, p-MOD) are defined and determined by quantification of the modified fragments in hydrogel digestion by size exclusion chromatography combined with mass spectrometry (SEC-MS). The digestion products of a novel hyaluronidase HAase-B produced by Bacillus sp. A50 are studied and only a few modified fragments are identified by (1)H NMR and MS. As a result, Three HA hydrogels prepared in lab have different t-MOD, c-MOD and p-MOD, but the ratio of c-MOD to p-MOD result in the almost same value of 75%. Hydrogel products from Q-Med have nearly same t-MOD about 0.8% and c-MOD about 0.1%, the ratio of c-MOD to p-MOD is about 13%. Hydrogels from ANTEIS S.A all have much higher t-MOD values, the ratio of c-MOD and p-MOD is about 8%.

  13. Determination of humic and fulvic acids in commercial solid and liquid humic products by alkaline extraction and gravimetric determination

    Science.gov (United States)

    Increased use of humic substances in agriculture has generated intense interest among producers, consumers, and regulators for an accurate and reliable method for quantification of humic (HA) and fulvic acids (FA) in raw ores and products. Here we present a thoroughly validated method, the Humic Pro...

  14. Development of analytical methods for the determination of tenuazonic acid analogues in food commodities.

    Science.gov (United States)

    Asam, Stefan; Lichtenegger, Martina; Muzik, Kornelija; Liu, Yang; Frank, Oliver; Hofmann, Thomas; Rychlik, Michael

    2013-05-10

    Analogues of the Alternaria mycotoxin tenuazonic acid (TA, biosynthesized by the fungus from the amino acid isoleucine) derived from valine (ValTA), leucine (LeuTA), alanine (AlaTA) and phenylalanine (PheTA) were synthesized and characterized by mass spectrometry (MS) and (1)H nuclear magnetic resonance (NMR) spectroscopy. Concentrations of stock solutions were determined by quantitative (1)H NMR (qHNMR). Two analytical methods based on high performance liquid chromatography (HPLC) and MS detection were developed, one with derivatization with 2,4-dinitrophenylhydrazine (DNPH) and one without derivatization. Limits of detection (LODs) were between 1-3 μg/kg (with derivatization) and 50-80 μg/kg (without derivatization). Respective limits of quantitation (LOQs) were about three times higher. Beside TA, the analogues LeuTA (about 4% of TA content) and ValTA (about 10% of TA content) were found in highly contaminated sorghum infant cereals and sorghum grains. Other analogues were not detected. Quantification of LeuTA and ValTA was performed using [(13)C6,(15)N]-TA as internal standard and matrix matched calibration. Recovery was between 95±11% and 102±10% for both compounds. Precision (relative standard deviation of triplicate sorghum cereal analyses three times during 3 weeks) was 7% for TA (912±60 μg/kg), 17% for LeuTA (43±8 μg/kg) and 19% for ValTA (118±22 μg/kg). These results indicate that several TA-like compounds, which are not yet characterized in aspects of their toxic properties, were detected in sorghum based infant food highly contaminated with TA, already.

  15. Quantitative determination of urinary trichloroacetic acid as an index of trichloroethylene exposure by high performance liquid chromatography.

    Directory of Open Access Journals (Sweden)

    Ogata,Masana

    1979-12-01

    Full Text Available A high performance lipuid chromatographic method for the determination of urinary trichloroacetic acid, a metabolite of trichloroethylene, is described. A stainless steel column packed with Hitachi gel 2618 (H form was used and the mobile phase was one per cent aqueous phosphoric acid. Urine can be analyzed directly without any solvent extraction or pretreatment. The minimal detection limit was 0.5 micrograms per analysis. The present method is simple and specific, and can be performed within 10 min.

  16. Electrocatalytic oxidation and voltammetric determination of ciprofloxacin employing poly(alizarin red)/graphene composite film in the presence of ascorbic acid, uric acid and dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xin; Wei, Youli; Ding, Yaping, E-mail: wdingyp@sina.com

    2014-07-04

    Graphical abstract: An electrochemical sensor based on PAR/EGR/GCE via a cooperation of the potentiostatic technique and cyclic voltammetry was first fabricated for the determination of CPFX with satisfied detecting result of real samples. - Highlights: • PAR/EGR composite film was prepared for the first time. • The sensor can be applied to determinate CPFX in the presence of AA, UA and DA. • The sensor indicated the feasibility in drug samples and biological media. - Abstract: A glassy carbon electrode modified with poly(alizarin red)/electrodeposited graphene (PAR/EGR) composite film was prepared and applied to detect ciprofloxacin (CPFX) in the presence of ascorbic, uric acid and dopamine. The morphology and interface property of PAR/EGR films were examined by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrocatalytic oxidation of CPFX on AR/EGR was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The linearity ranged from 4 × 10{sup −8} to 1.2 × 10{sup −4} M with a detection limit (S/N = 3) of 0.01 μM. The modified electrode could be applied to the individual determination of CPFX as well as the simultaneous determination of CPFX, ascorbic acid, uric acid and dopamine. This method proved to be a simple, selective and rapid way to determine CPFX in pharmaceutical preparation and biological media.

  17. Isolation, structure determination, synthesis, and sensory activity of N-phenylpropenoyl-L-amino acids from cocoa (Theobroma cacao).

    Science.gov (United States)

    Stark, Timo; Hofmann, Thomas

    2005-06-29

    Application of chromatographic separation and taste dilution analyses recently revealed besides procyanidins a series of N-phenylpropenoyl amino acids as the key contributors to the astringent taste of nonfermented cocoa beans as well as roasted cocoa nibs. Because these amides have as yet not been reported as key taste compounds, this paper presents the isolation, structure determination, and sensory activity of these amino acid amides. Besides the previously reported (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-3-hydroxy-L-tyrosine (clovamide), (-)-N-[4'-hydroxy-(E)-cinnamoyl]-L-tyrosine (deoxyclovamide), and (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-tyrosine, seven additional amides, namely, (+)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-aspartic acid, (+)-N-[4'-hydroxy-(E)-cinnamoyl]-L-aspartic acid, (-)-N-[3',4'-dihydroxy-(E)-cinnamoyl]-L-glutamic acid, (-)-N-[4'-hydroxy-(E)-cinnamoyl]-L-glutamic acid, (-)-N-[4'-hydroxy-(E)-cinnamoyl]-3-hydroxy-L-tyrosine, (+)-N-[4'-hydroxy-3'-methoxy-(E)-cinnamoyl]-L-aspartic acid, and (+)-N-[(E)-cinnamoyl]-L-aspartic acid, were identified for the first time in cocoa products by means of LC-MS/MS, 1D/2D-NMR, UV-vis, CD spectroscopy, and polarimetry, as well as independent enantiopure synthesis. Using the recently developed half-tongue test, human recognition thresholds for the astringent and mouth-drying oral sensation were determined to be between 26 and 220 micromol/L (water) depending on the amino acid moiety. In addition, exposure to light rapidly converted these [E]-configured N-phenylpropenoyl amino acids into the corresponding [Z]-isomers, thus indicating that analysis of these compounds in food and plant materials needs to be performed very carefully in the absence of light to prevent artifact formation.

  18. Simultaneous determination of EDTA, sorbic acid, and diclofenac sodium in pharmaceutical preparations using high-performance liquid chromatography.

    Science.gov (United States)

    Heydari, Rouhollah; Shamsipur, Mojtaba; Naleini, Nasim

    2013-06-01

    A simple high-performance liquid chromatographic method for simultaneous determination of ethylenediaminetetraacetic acid (EDTA), sorbic acid, and diclofenac sodium was developed and validated. Separation was achieved on a C(18) column (10 cm×4.6 mm) using gradient elution. The mobile phase consisted of acetonitrile-ammonium dihydrogen phosphate buffer solution (0.01 M, pH=2.5, containing 0.8% tetra-n-butyl ammonium hydroxide). The detector wavelength was set at 254 nm. Under these conditions, separation of three compounds was achieved in less than 10 min. The effect of two metal salts and metal concentration on peak area of EDTA was investigated. The pH effect on retention of EDTA and sorbic acid was studied. The method showed linearity for EDTA, sorbic acid, and diclofenac in the ranges of 2.5-100.0, 5.0-200.0, and 20.0-120.0 μg/mL, respectively. The within- and between-day relative standard deviations ranged from 0.52 to 1.94%, 0.50 to 1.34%, and 0.78 to 1.67% for EDTA, sorbic acid, and diclofenac, respectively. The recovery of EDTA, sorbic acid, and diclofenac from pharmaceutical preparation ranged from 96.0-102.0%, 99.7-101.5%, to 97.0-102.5%, respectively. To the best of our knowledge, this is the first report about simultaneous determination of EDTA, sorbic acid, and diclofenac.

  19. Determination of tolerable fatty acids and cholera toxin concentrations using human intestinal epithelial cells and BALB/c mouse macrophages.

    Science.gov (United States)

    Tamari, Farshad; Tychowski, Joanna; Lorentzen, Laura

    2013-05-30

    The positive role of fatty acids in the prevention and alleviation of non-human and human diseases have been and continue to be extensively documented. These roles include influences on infectious and non-infectious diseases including prevention of inflammation as well as mucosal immunity to infectious diseases. Cholera is an acute intestinal illness caused by the bacterium Vibrio cholerae. It occurs in developing nations and if left untreated, can result in death. While vaccines for cholera exist, they are not always effective and other preventative methods are needed. We set out to determine tolerable concentrations of three fatty acids (oleic, linoleic and linolenic acids) and cholera toxin using mouse BALB/C macrophages and human intestinal epithelial cells, respectively. We solubilized the above fatty acids and used cell proliferation assays to determine the concentration ranges and specific concentrations of the fatty acids that are not detrimental to human intestinal epithelial cell viability. We solubilized cholera toxin and used it in an assay to determine the concentration ranges and specific concentrations of cholera toxin that do not statistically decrease cell viability in BALB/C macrophages. We found the optimum fatty acid concentrations to be between 1-5 ng/μl, and that for cholera toxin to be cholera infections.

  20. Enzymatic Method for Rapid Determination of Oxalic Acid in Bleaching Filtrates from the Pulp and Paper Industry

    Institute of Scientific and Technical Information of China (English)

    HONG Feng; SJ(O)DE Anders; NILVEBRANT Nils-Olof; J(O)NSSON Leif J.

    2005-01-01

    Bleaching with oxygen-containing agents and recirculation of process streams in the pulp and paper industry has increased the accumulation of oxalic acid and danger for precipitation of calcium oxalate encrusts, scaling. Analysis and control of oxalic acid in bleaching filtrates is therefore becoming increasingly important in the pulp and paper industry.Chromatographic methods, such as IC and HPLC, are generally more time-consuming but are valuable as standard methods for determination of oxalic acid. However, the instrumentation needed is expensive and stationary. In this study, an enzymatic method based on oxalate oxidase and peroxidase was developed to determine oxalic acid in authentic bleaching filtrates using a spectrophotometer. The results showed that bleaching filtrates contain some compounds interfering with the enzymatic method.Pretreatment of the samples with activated charcoal was a successful approach for decreasing problems with interference. By using dilution followed by charcoal treatment, the results obtained from five bleaching filtrates with the colorimetric method correlated very well with those obtained using IC. This study offers a selective, fast and mobile analysis method to determine oxalic acid in bleaching filtrates from the pulp and paper industry. The convenient enzyme-based method improves the possibilities for control of critical oxalic acid concentrations in closed-loop bleaching streams.

  1. [Rapid determination of fatty acids in soybeans [Glycine max (L.) Merr.] by FT-near-infrared reflectance spectroscopy].

    Science.gov (United States)

    Sun, Jun-ming; Han, Fen-xia; Yan, Shu-rong; Yang, Hua; Tetsuo, Sato

    2008-06-01

    Current breeding programs dealing with fatty acid (FA) concentrations in soybean [Glycine max (L. ) Merr.] require large numbers for gas chromatographic analyses, thus it is important to develop a method for rapid determination of fatty acid by Near-Infrared Reflectance spectroscopy (NIRS) in soybeans. The objective of this work was to study the potential of fourier-transform near-infrared reflectance spectroscopy (FT-NIRS) to estimate the fatty acid concentrations in Chinese soybean varieties. One hundred and eight of soybean cultivars or lines (the calibration set: 64; the external validation set: 44) were scanned within 4000-12500 cm(-1) of wavenumbers using a standard sample cup by NIRS machinery, and analyzed the fatty acids by gas chromatograph (GC) methods. Equations were developed using partial least squares (PLS) regression and cross validation for multivariate calibration in this study. The optimal spectral region was selected from 6101.9 to 5446.5 cm(-1) based on the OPUS 5.0 software. Cross validation results showed that major FA components such as oleic acid (R2(CV) = 0.94), linoleic acid (R2(CV) = 0.87), linolenic acid (R2(CV) = 0.85), and total saturates (R2(CV) = 0.88) were accurately determined by the proposed equations as compared with the reference data obtained by the GC method. External validation results also demonstrated that equation for oleic acid had the highest predictive ability R(2)val = 0.91), root mean square error of predication (RMSEP) value was 2.47 g x kg(-1) dry weight, the ratios of RMSEP to the standard deviation (SD) was 0.29, which was usable for quality assurance application. Moreover, equations for palmitic acid, stearic acid, linoleic acid, linolenic acid, and total saturates were predicted with the determination coefficients ranging from 0.66 to 0.76, RMSEP values from 0.37 to 2.74 g x kg(-1) dry weight, and RMSEP/SD values from 0.47 to 0.53, which could be used for sample screening. Therefore, we confirmed that a

  2. Selective Voltammetric Determination of Uric Acid in the Presence of Ascorbic Acid at Ordered Mesoporous Carbon Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    WEN,Yan-Li; JIA,Neng-Qin; WANG,Zhi-Yong; SHEN,He-Bai

    2008-01-01

    A novel chemically modified electrode was fabricated by immobilizing ordered mesoporous carbon (OMC)onto a glassy carbon (GC) electrode.The electrocatalytic behavior of the OMC modified electrode towards the oxidation of uric acid (UA) and ascorbic acid (AA) was studied.Compared to a glassy carbon electrode,the OMC modified electrode showed a faster electron transfer rate and reduced the overpotentials greatly.Furthermore,the OMC modified electrode resolved the overlapping voltammetric responses of UA and AA into two well-defined voltammetric peaks with peak separation of ca.0.38 V.All results show that the OMC modified electrode has a good electrocatalytic ability to UA and AA,and has an excellent response towards UA even in the presence of high concentration AA.

  3. Determination of urinary vanillylmandelic acid and homovanillic acid by high performance liquid chromatography for mass screening of neuroblastoma.

    Science.gov (United States)

    Sato, Y; Hanai, J; Takasugi, N; Takeda, T

    1986-10-01

    In order to develop a mass screening method for the early detection of neuroblastoma, we measured urinary vanillylmandelic acid (VMA) and homovanillic acid (HVA) by a high performance liquid chromatography (HPLC) equipped with an electrochemical detector. Urinary samples were collected on a piece of filter paper and then pre-treated by a simple method. Measurement of VMA and HVA was performed within a short period of time, and by about 80 samples per a day could be analyzed by automatic system. The method described herein proved to be reliable, and we thus recommend it as a useful method for measurement of both VMA and HVA, leading to more accurate detection of neuroblastoma in mass screening test.

  4. Simultaneous extraction and HPLC determination of 3-indole butyric acid and 3-indole acetic acid in pea plant by using ionic liquid-modified silica as sorbent.

    Science.gov (United States)

    Sheikhian, Leila; Bina, Sedigheh

    2016-01-15

    In this study, ionic liquid-modified silica was used as sorbent for simultaneous extraction and preconcentration of 3-indole butyric acid and 3-indole acetic acid in pea plants. The effect of some parameters such as pH and ionic strength of sample solution, amount of sorbent, flow rate of aqueous sample solution and eluent solution, concentration of eluent solution, and temperature were studied for each hormone solution. Percent extraction of 3-indole butyric acid and 3-indole acetic acid was strongly affected by pH of aqueous sample solution. Ionic strength of aqueous phase and temperature showed no serious effects on extraction efficiency of studied plant hormones. Obtained breakthrough volume was 200mL for each of studied hormones. Preconcentration factor for spectroscopic and chromatographic determination of studied hormones was 100 and 4.0×10(3) respectively. Each solid sorbent phase was reusable for almost 10 times of extraction/stripping procedure. Relative standard deviations of extraction/stripping processes of 3-indole butyric acid and 3-indole acetic acid were 2.79% and 3.66% respectively. The calculated limit of detections for IBA and IAA were 9.1×10(-2)mgL(-1) and 1.6×10(-1)mgL(-1) respectively.

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Magdalena Godlewska

    2015-01-01

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

  7. Flow—injection Chemiluminescence Sensor for the Determination of Gallic Acid by Immobilizing Luminol and Periodate on Anionexchange Resin

    Institute of Scientific and Technical Information of China (English)

    鞠Huang先; 张四纯; 周国俊

    2002-01-01

    A novel chemiluminescence (CL) sensor for the determination of gallic acld combined with folw injection analysis was developed by electrostatically immobilizing hminol and periodate on anion-exchange resins respectively.Gallic acid was sensed by its enhancing effect on the weak CL reaction between luminol and periodate,which were eluted from the ion exchange column.The possible reaction mechanism of the CL system was suggested and discussed.The response of the sensor to gallic acid concentration was linear over the range of 8.0×10-—1.0×10-6mol/L with a detection limit of 6.5×10-9 mol/L(3σ).The relative standard deviation (RSD) for 7 repetitive determinations of gallic acid(1.0×10-7mol/L) was 1.8?The sensor could be used for over 400 times determination with a good reproducibility.

  8. Four-way calibration applied to the simultaneous determination of folic acid and methotrexate in urine samples.

    Science.gov (United States)

    Muñoz de la Peña, A; Durán Merás, I; Jiménez Girón, A

    2006-08-01

    First-, second- and third-order calibration methods were investigated for the simultaneous determination of folic acid and methotrexate. The interest in the determination of these compounds is related to the fact that methotrexate inhibits the body's absorption of folic acid and prolonged treatment with methotrexate may lead to folic acid deficiency, and to the use of folic acid to cope with toxic side effects of methotrexate. Both analytes were converted into highly fluorescent compounds by oxidation with potassium permanganate, and the kinetics of the reaction was continuously monitored by recording the kinetics curves of fluorescence emission, the evolution with time of the emission spectra and the excitation-emission matrices (EEMs) of the samples at different reaction times. Direct determination of mixtures of both drugs in urine was accomplished on the basis of the evolution of the kinetics of EEMs by fluorescence measurements and four-way parallel-factor analysis (PARAFAC) or multiway partial least squares (N-PLS) chemometric calibration. The core consistency diagnostic (CORCONDIA) was employed to determine the correct number of factors in PARAFAC and the procedure converged to a choice of three factors, attributed to folic acid, methotrexate and to the sum of fluorescent species present in the urine.

  9. Enantiomeric fraction determination of 2-arylpropionic acids in a package plant membrane bioreactor.

    Science.gov (United States)

    Hashim, Nor H; Stuetz, Richard M; Khan, Stuart J

    2013-05-01

    Enantiomeric compositions of three 2-arylpropionic acid (2-APA) drugs, ibuprofen, naproxen, and ketoprofen, were monitored in a membrane bioreactor (MBR) treating municipal effluent in a small rural town in Australia. Specific enantiomers were determined as amide diastereomers using the chiral derivatizing reagent, (R)-1-phenylethylamine (PEA), followed by gas chromatography-tandem mass spectrometry (GC-MS/MS). The six individual enantiomers were quantified by isotope dilution and the enantiomeric fractions (EFs) were determined. Over four separate sampling events, ibuprofen EF ranged from 0.88 to 0.94 (median 0.93) in the influent and 0.38 to 0.40 (median 0.39) in the effluent. However, no significant change in ketoprofen EF was observed, with influent EFs of 0.56-0.60 (median 0.58) and effluent EFs 0.54-0.68 (median 0.56). This is the first report of enantiospecific analysis of ketoprofen in municipal wastewater and it is not yet clear why such different behavior was observed compared to ibuprofen. Naproxen EF was consistently measured at 0.99 in the influent and ranged from 0.86 to 0.94 (median 0.91) in the effluent. This study demonstrates that EF is a relatively stable parameter and does not fluctuate according to concentration or other short-term variables introduced by sampling limitations. The enantiospecific analysis of chiral chemicals presents a promising approach to elucidate a more thorough understanding of biological treatment processes and a potential tool for monitoring the performance of key biological pathways.

  10. GC-FID determination and pharmacokinetic studies of oleanolic acid in human serum.

    Science.gov (United States)

    Rada, Mirela; Castellano, José María; Perona, Javier S; Guinda, Ángeles

    2015-11-01

    Analytical interest of OA determination in human serum has increased owing to the increasing interest in pharmaceutical research by pharmaceutical properties. A simple, specific, precise and accurate GC method with flame ionization detector (FID) developed and validated for the determination of oleanolic acid (OA) in human serum (HS). To an aliquot of HS, internal standard was added and a combination of liquid-liquid extraction with a mixture of diethyl ether-isopropyl alcohol, filtration and consecutive GC resulted in separation and quantification of OA. The organic phase was analyzed using a GC system equipped with a 30 × 0.25 mm i.d. Rtx-65TG capillary column and FID detection. Total chromatographic time was 10 min and no interfering peaks from endogenous components in blank serum were observed. The OA/internal standard peak area ratio was linearly fitted to the OA concentration (r = 0.992) over the range 10-1500 ng/mL. The mean serum extraction recovery of OA was 96.7 ± 1.0% and the lower limit of quantification based on 5 mL of serum was 10.7 ng/mL. The intra-day coefficient of variation ranged from 1.3 to 3.6% and inter-day varied from 1.4 to 4.5%. The developed method was used to study the pharmacokinetics of OA after oral administration in humans. The assay was simple, sensitive, precise and accurate for the use in the study of the mechanisms of absorption and distribution of OA in humans.

  11. Identification of crucial amino acids in mouse aldehyde oxidase 3 that determine substrate specificity.

    Directory of Open Access Journals (Sweden)

    Martin Mahro

    Full Text Available In order to elucidate factors that determine substrate specificity and activity of mammalian molybdo-flavoproteins we performed site directed mutagenesis of mouse aldehyde oxidase 3 (mAOX3. The sequence alignment of different aldehyde oxidase (AOX isoforms identified variations in the active site of mAOX3 in comparison to other AOX proteins and xanthine oxidoreductases (XOR. Based on the structural alignment of mAOX3 and bovine XOR, differences in amino acid residues involved in substrate binding in XORs in comparison to AOXs were identified. We exchanged several residues in the active site to the ones found in other AOX homologues in mouse or to residues present in bovine XOR in order to examine their influence on substrate selectivity and catalytic activity. Additionally we analyzed the influence of the [2Fe-2S] domains of mAOX3 on its kinetic properties and cofactor saturation. We applied UV-VIS and EPR monitored redox-titrations to determine the redox potentials of wild type mAOX3 and mAOX3 variants containing the iron-sulfur centers of mAOX1. In addition, a combination of molecular docking and molecular dynamic simulations (MD was used to investigate factors that modulate the substrate specificity and activity of wild type and AOX variants. The successful conversion of an AOX enzyme to an XOR enzyme was achieved exchanging eight residues in the active site of mAOX3. It was observed that the absence of the K889H exchange substantially decreased the activity of the enzyme towards all substrates analyzed, revealing that this residue has an important role in catalysis.

  12. Acid base surface properties of glass-ionomers determined by IGC

    Science.gov (United States)

    Voelkel, A.; Andrzejewska, E.; Limanowska-Shaw, H.; Andrzejewski, M.

    2005-05-01

    SummaryThe surface properties of several glass-ionomer restorative dental materials (GC Fuji, Chemadent G-J, Ketac Fil and Ketac Molar) were investigated by means of inverse gas chromatography. The capacity of the surface of glass-ionomers to undergo specific interactions was expressed using the specific component of free energy Δ Gs as well as the parameters KA and KD to describe the ability of the cement to act both as an electron acceptor and an electron donor, respectively. The character of the examined surface was expressed with the use of the SC parameter. All these parameters were determined with a high degree of precision. It was found that the surface of glass-ionomer cements had a well-marked acidic character. The ability of the cement surface to take part in specific interactions differed with the various types of commercial products. The surface activity of the glass-ionomers investigated changed with the storage time (up to 6 months) indicating an on-going setting reaction.

  13. Spectrofluorimetric determination of 5-fluorouracil by fluorescence quenching of 9-anthracenecarboxylic acid

    Science.gov (United States)

    Khot, M. S.; Bhattar, S. L.; Kolekar, G. B.; Patil, S. R.

    2010-09-01

    Photo-induced intermolecular electron transfer (PET) interaction between excited singlet (S 1) state of 9-anthracene carboxylic acid (9-ANCA) and DNA bases of pyrimidines as uracil and 5-fluorouracil (5-FU) has been studied in water and ethanol solutions using steady-state fluorescence spectroscopy. The intensity of all emission bands of 9-ANCA was quenched in presence of uracil and 5-FU by electron transfer reaction without formation of an exciplex. It was found that uracil and 5-fluorouracil acts as effective electron donors and simultaneously quench the fluorescence of electron-accepting sensitizer 9-ANCA. The quenching by diffusion-controlled rate coincides well with the dynamic Stern-Volmer correlation. The bimolecular quenching rate constant (kqss) and electron transfer rate constant ( ket) observed are seen to be much higher for 5-fluorouracil than those for uracil. The thermodynamic parameters estimated by using the Rehm-Weller equation were used to propose a suitable mechanism for PET occurring between uracils and 9-ANCA. The proposed method was used to determine 5-fluorouracil from pharmaceutical samples with satisfactory results. The technique is more selective, sensitive and relatively free from coexisting substances.

  14. Electrochemical Molecular Imprinted Sensors Based on Electrospun Nanofiber and Determination of Ascorbic Acid.

    Science.gov (United States)

    Zhai, Yunyun; Wang, Dandan; Liu, Haiqing; Zeng, Yanbo; Yin, Zhengzhi; Li, Lei

    2015-01-01

    In this study, electrochemical molecularly imprinted sensors were fabricated and used for the determination of ascorbic acid (AA). Nanofiber membranes of cellulose acetate (CA)/multi-walled carbon nanotubes (MWCNTs)/polyvinylpyrrolidone (PVP) (CA/MWCNTs/PVP) were prepared by electrospinning technique. After being transferred to a glass carbon electrode (GC), the nanofiber interface was further polymerized with pyrrole through electrochemical cyclic voltammetry (CV) technique. Meanwhile, target molecules (such as AA) were embedded into the polypyrrole through the hydrogen bond. The effects of monomer concentration (pyrrole), the number of scan cycles and scan rates of polymerization were optimized. Differential pulse voltammetry (DPV) tests indicated that the oxidation current of AA (the selected target) were higher than that of the structural analogues, which illustrated the selective recognition of AA by molecularly imprinted sensors. Simultaneously, the molecularly imprinted sensors had larger oxidation current of AA than non-imprinted sensors in the processes of rebinding. The electrochemical measurements showed that the molecularly imprinted sensors demonstrated good identification behavior for the detection of AA with a linear range of 10.0 - 1000 μM, a low detection limit down to 3 μM (S/N = 3), and a recovery rate range from 94.0 to 108.8%. Therefore, the electrochemical molecularly imprinted sensors can be used for the recognition and detection of AA without any time-consuming elution. The method presented here demonstrates the great potential for electrospun nanofibers and MWCNTs to construct electrochemical sensors.

  15. Determination of mycophenolic acid in human plasma by ultra performance liquid chromatography tandem mass spectrometry

    Directory of Open Access Journals (Sweden)

    Vivek Upadhyay

    2014-06-01

    Full Text Available A simple, sensitive and high throughput ultra performance liquid chromatography tandem mass spectrometry method has been developed for the determination of mycophenolic acid in human plasma. The method involved simple protein precipitation of MPA along with its deuterated analog as an internal standard (IS from 50 µL of human plasma. The chromatographic analysis was done on Acquity UPLC C18 (100 mm×2.1 mm, 1.7 µm column under isocratic conditions using acetonitrile and 10 mM ammonium formate, pH 3.00 (75:25, v/v as the mobile phase. A triple quadrupole mass spectrometer operating in the positive ionization mode was used for quantitation. In-source conversion of mycophenolic glucuronide metabolite to the parent drug was selectively controlled by suitable optimization of cone voltage, cone gas flow and desolvation temperature. The method was validated over a wide concentration range of 15–15000 ng/mL. The mean extraction recovery for the analyte and IS was >95%. Matrix effect expressed as matrix factors ranged from 0.97 to 1.02. The method was successfully applied to support a bioequivalence study of 500 mg mycophenolate mofetil tablet in 72 healthy subjects.

  16. Determination of L-ascorbic acid in Lycopersicon fruits by capillary zone electrophoresis.

    Science.gov (United States)

    Galiana-Balaguer, L; Roselló, S; Herrero-Martínez, J M; Maquieira, A; Nuez, F

    2001-09-15

    This study shows an improved method for the determination of L-ascorbic acid (l-AA) in fruits of Lycopersicon by capillary zone electrophoresis (CZE). Two backgrounds electrolytes (BGEs) have been tested: (i) 400 mM borate at pH 8.0 and 1 x 10(-2)% hexadimethrine bromide, for the separation of Eulycopersicon subgenus species; and (ii) as in BGE(i) but supplemented with 20% (v/v) acetonitrile, for the separation of species of the Eriopersicon subgenus. The present procedures were compared with two routine methods-enzymatic assay and potentiometric titration with 2,6-dichlorophenol-indophenol. While these routine methods presented some difficulties in quantifying l-AA in several Lycopersicon fruits, CZE was successfully applied in all the analyzed samples. The proposed CZE protocols give lower detection limits (<0.4 microg ml(-1)); are cheaper, quicker, and highly reproducible; and can be applied to analyze large series of samples (ca. 50 samples per day) which is utmost importance, not only in screening trials for internal quality and tomato breeding programs, but also in systematic and routine characterization of Lycopersicon fruits.

  17. Microemulsion electrokinetic chromatography as a suitable tool for lipophilicity determination of acidic, neutral, and basic compounds.

    Science.gov (United States)

    Subirats, Xavier; Yuan, Hui-Ping; Chaves, Verónica; Marzal, Núria; Rosés, Martí

    2016-07-01

    In the present work, several MEEKC systems are studied to assess their suitability for lipophilicity determination of acidic, neutral, and basic compounds. Thus, several microemulsion compositions over a wide range of pH values (from 2.0 to 12.0), containing heptane, 1-butanol and different types and amounts of surfactant (SDS or sodium cholate: from 1.3 to 3.3%) are characterized using Abraham's solvation model. The addition of acetonitrile (up to 10%) is also studied, since it increases the resolution of the technique for the most lipophilic compounds. The system coefficients obtained are very similar to those of the 1-octanol/water, used as the reference lipophilicity index, allowing simple and linear correlations between the 1-octanol/water partition values (log Po/w ) and MEEKC mass distribution ratios (log kMEEKC ). Variations in the microemulsion composition (aqueous buffer, surfactant, concentration of ACN) did not significantly affect the similarity of the MEEKC systems to log Po/w partition.

  18. Determination of mycophenolic acid in human plasma by ultra performance liquid chromatography tandem mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    Vivek Upadhyay; Vikas Trivedi; Gaurang Shah; Manish Yadav; Pranav S. Shrivastav

    2014-01-01

    A simple, sensitive and high throughput ultra performance liquid chromatography tandem mass spectrometry method has been developed for the determination of mycophenolic acid in human plasma. The method involved simple protein precipitation of MPA along with its deuterated analog as an internal standard (IS) from 50 mL of human plasma. The chromatographic analysis was done on Acquity UPLC C18 (100mm*2.1mm,1.7mm) column under isocratic conditions using acetonitrile and 10 mM ammonium formate, pH 3.00 (75:25, v/v) as the mobile phase. A triple quadrupole mass spectrometer operating in the positive ionization mode was used for quantitation. In-source conversion of mycophenolic glucuronide metabolite to the parent drug was selectively controlled by suitable optimization of cone voltage, cone gas flow and desolvation temperature. The method was validated over a wide concentration range of 15–15000 ng/mL. The mean extraction recovery for the analyte and IS was 495%. Matrix effect expressed as matrix factors ranged from 0.97 to 1.02. The method was successfully applied to support a bioequivalence study of 500 mg mycophenolate mofetil tablet in 72 healthy subjects.

  19. Synthesis and acid digestion of biomorphic ceramics: determination of alkaline and alkaline earth ions.

    Science.gov (United States)

    Bosch Ojeda, Catalina; Sánchez Rojas, Fuensanta; Cano Pavón, José Manuel

    2007-09-01

    Ceramic and glass are some of the more recent engineering materials and those that are most resistant to environmental conditions. They belong to advanced materials in that they are being developed for the aerospace and electronics industries. In the last decade, a new class of ceramic materials has been the focus of particular attention. The materials were produced with natural, renewable resources (wood or wood-based products). In this work, we have synthesised a new biomorphic ceramic material from oak wood and Si infiltration. After the material characterization, we have optimized the dissolution of the sample by acid attack in an oven under microwave irradiation. Experimental designs were used as a multivariate strategy for the evaluation of the effects of varying several variables at the same time. The optimization was performed in two steps using factorial design for preliminary evaluation and a Draper-Lin design for determination of the critical experimental conditions. Five variables (time, power, volume of HNO3, volume H2SO4 and volume of HF) were considered as factors and as a response the concentration of different metal ions in the optimization process. Interactions between analytical factors and their optimal levels were investigated using a Draper-Lin design.

  20. Allosteric Inhibition of Phosphoenolpyruvate Carboxylases is Determined by a Single Amino Acid Residue in Cyanobacteria

    Science.gov (United States)

    Takeya, Masahiro; Hirai, Masami Yokota; Osanai, Takashi

    2017-01-01

    Phosphoenolpyruvate carboxylase (PEPC) is an important enzyme for CO2 fixation and primary metabolism in photosynthetic organisms including cyanobacteria. The kinetics and allosteric regulation of PEPCs have been studied in many organisms, but the biochemical properties of PEPC in the unicellular, non-nitrogen-fixing cyanobacterium Synechocystis sp. PCC 6803 have not been clarified. In this study, biochemical analysis revealed that the optimum pH and temperature of Synechocystis 6803 PEPC proteins were 7.3 and 30 °C, respectively. Synechocystis 6803 PEPC was found to be tolerant to allosteric inhibition by several metabolic effectors such as malate, aspartate, and fumarate compared with other cyanobacterial PEPCs. Comparative sequence and biochemical analysis showed that substitution of the glutamate residue at position 954 with lysine altered the enzyme so that it was inhibited by malate, aspartate, and fumarate. PEPC of the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 was purified, and its activity was inhibited in the presence of malate. Substitution of the lysine at position 946 (equivalent to position 954 in Synechocystis 6803) with glutamate made Anabaena 7120 PEPC tolerant to malate. These results demonstrate that the allosteric regulation of PEPC in cyanobacteria is determined by a single amino acid residue, a characteristic that is conserved in different orders. PMID:28117365

  1. Determination of iodide using flow injection with acidic potassium permanganate chemiluminescence detection.

    Science.gov (United States)

    Yaqoob, Mohammad; Atiq-ur-Rehman; Waseem, Amir; Nabi, Abdul

    2006-01-01

    A simple and rapid flow-injection method is described for the determination of iodide, based on potassium permanganate chemiluminescence detection via oxidation of formaldehyde in aqueous hydrochloric acid. The calibration graph was linear over the range 1.0-12 x 10(-6) mol/L (r2 = 0.9955) with relative standard deviations (n = 4) in the range 1.0-3.5%. The detection limit (3sigma) was 1.0 x 10(-7) mol/L, with sample throughput of 120/h. The effect of interfering cations [Ca(II), Mg(II), Ni(II), Fe(II), Fe(III) and Pb(II)] and anions (Cl-, SO4(2-), PO4(3-), NO3-, NO2-, F- and SO3(2-)) were studied. The method was applied to iodized salt samples and the results obtained in the range 0.03 +/- 0.005 - 0.10 +/- 0.006 mg I/g were in reasonable agreement with the amount labelled. The method was statistically compared with the results obtained by titration; no significant disagreement at 95% confidence was observed.

  2. Urinary 4-hydroxy-3-methoxymandelic (vanillylmandelic) acid, 4-hydroxy-3-methoxyphenylacetic (homovanillic) acid, and 5-hydroxy-3-indoleacetic acid determined by liquid chromatography with electrochemical detection.

    Science.gov (United States)

    Fujita, K; Maruta, K; Ito, S; Nagatsu, T

    1983-05-01

    We describe a simple liquid-chromatographic assay of urinary 4-hydroxy-3-methoxymandelic (vanillylmandelic) acid, 4-hydroxy-3-methoxyphenylacetic (homovanillic) acid, and 5-hydroxy-3-indoleacetic acid with electrochemical detection, with direct injection of the sample. The first two analytes are measured simultaneously; 5-hydroxy-3-indoleacetic acid is measured separately. Chromatographic conditions for assay of the three were: column temperature, 65 and 60 degrees C; mobile phase, potassium phosphate buffer (0.2 mol/L, pH 3.0) for 6 min, then potassium phosphate buffer plus acetonitrile (9/1 by vol) for 20 min; flow rate, 0.7 mL/min; oxidation potential, 600 and 450 mV vs an Ag/AgCl reference electrode; and sensitivity, 40 and 160 nA at full scale. Values so obtained agreed well with those obtained for samples that were first solvent-extracted.

  3. Simultaneous liquid chromatographic determination of vanillylmandelic acid, homovanillic acid, and 5-hydroxy-3-indoleacetic acid in urine, using isocratic elution and electrochemical detection.

    Science.gov (United States)

    Richards, D A; Titheradge, A C

    1987-01-01

    A method for the simultaneous measurement of vanillylmandelic acid, homovanillic acid and 5-hydroxyindoleacetic acid in urine is described. Based on reversed-phase liquid chromatography with electrochemical detection, the procedure employs isocratic elution, thus making it suitable for use in the less well-equipped clinical or research laboratory. A simple extraction of the acids from acidified urine into ethyl acetate, is followed by evaporating to dryness a portion of the organic layer, and redissolving the residue in chromatographic mobile phase. Up to 20 samples can be analysed in a single working day. The method is validated and the results obtained are compared with reference methods. The cause of contamination of the glassy carbon surface of the working electrode is investigated, and a simple electrochemical pretreatment is described that overcomes this problem. Finally, the extra clinical information that can be derived from multi-metabolite assays is considered.

  4. Estudio numerico y experimental del proceso de soldeo MIG sobre la aleacion 6063--T5 utilizando el metodo de Taguchi

    Science.gov (United States)

    Meseguer Valdenebro, Jose Luis

    improvement on mechanical properties in aluminum metal joint. Los procesos de soldadura por arco electrico representan unas de las tecnicas mas utilizadas en los procesos de fabricacion de componentes mecanicos en la industria moderna. Los procesos de soldeo por arco se han adaptado a las necesidades actuales, haciendose un modo de fabricacion flexible y versatil. Los resultados obtenidos numericamente en el proceso de soldadura son validados experimentalmente. Los principales metodos numericos mas empleados en la actualidad son tres, metodo por diferencias finitas, metodos por elementos finitos y metodo por volumenes finitos. El metodo numerico mas empleado para el modelado de uniones soldadas, es el metodo por elementos finitos, debido a que presenta una buena adaptacion a las condiciones geometricas y de contorno ademas de que existe una diversidad de programas comerciales que utilizan el metodo por elementos finitos como base de calculo. Este trabajo de investigacion presenta un estudio experimental de una union soldada mediante el proceso MIG de la aleacion de aluminio 6063-T5. El metodo numerico se valida experimentalmente aplicando el metodo de los elementos finitos con el programa de calculo ANSYS. Los resultados experimentales obtenidos son: las curvas de enfriamiento, el tiempo critico de enfriamiento t4/3, geometria del cordon, microdurezas obtenidas en la union soldada, zona afectada termicamente y metal base, dilucion del proceso, areas criticas intersecadas entre las curvas de enfriamiento y la curva TTP. Los resultados numericos son: las curvas del ciclo termico, que representan tanto el calentamiento hasta alcanzar la temperatura maxima y un posterior enfriamiento. Se calculan el tiempo critico de enfriamiento t4/3, el rendimiento termico y se representa la geometria del cordon obtenida experimentalmente. La zona afectada termicamente se obtiene diferenciando las zonas que se encuentran a diferentes temperaturas, las areas criticas intersecadas entre las

  5. Atlas de aves: Un metodo para documentar distribucion y seguir poblaciones

    Science.gov (United States)

    Robbins, C.S.; Dowell, B.A.; Dawson, D.K.; Alvarez-Lopez, Humberto; Kattan, Gustavo; Murcia, Carolina

    1988-01-01

    Los Atlas de Aves son proyectos nacionales o regionalies para trazar en mapas la distribucion en reproduccion de cada especie de ave. Ese procedimiento se esta usando en Europa, Australia, Nueva Zelanda, Norteamerica, y partes de Africa. El tama?o de los cuadrados varia de medio grado de latitud y Iongitud hasta 5 x 5 km. El trabajo de campo de cada proyecto exige aproxlmadamente cinco a?os, pero los aficionados pueden llevar a cabo la mayor parte del trabajo. Es posible almacenar los resultados en un computador personal. Hay muchos beneficios: (I) se presenta la distribucion corriente de las aves de la nacion, del estado, o de la Iocalidad; (2) se desarrolla nueva informacion especialmente sobre especies raras o en peligro; (3) se descubren areas que tienen una avlfauna sobresaliente o habitats raros y ayuda a su proteccion, (4) se documentan cambios de dlstribucion; (5) se pueden usar para documentar cambios de poblacion, especialmente en los tropicos donde otros metodos son mas dificiles de usar porque hay muchas especies y no hay muchos observadores calificados en la identificacion de sonidos de las aves; (6) son proyectos buenos de investigacion para estudiantes graduados; (7) los turistas y los jefes de excursiones de historia natural pueden contribuir con muchas informaciones

  6. Solution of rocks and refractory minerals by acids at high temperatures and pressures. Determination of silica after decomposition with hydrofluoric acid

    Science.gov (United States)

    May, I.; Rowe, J.J.

    1965-01-01

    A modified Morey bomb was designed which contains a removable nichromecased 3.5-ml platinium crucible. This bomb is particularly useful for decompositions of refractory samples for micro- and semimicro-analysis. Temperatures of 400-450?? and pressures estimated as great as 6000 p.s.i. were maintained in the bomb for periods as long as 24 h. Complete decompositions of rocks, garnet, beryl, chrysoberyl, phenacite, sapphirine, and kyanite were obtained with hydrofluoric acid or a mixture of hydrofluoric and sulfuric acids; the decomposition of chrome refractory was made with hydrochloric acid. Aluminum-rich samples formed difficultly soluble aluminum fluoride precipitates. Because no volatilization losses occur, silica can be determined on sample solutions by a molybdenum-blue procedure using aluminum(III) to complex interfering fluoride. ?? 1965.

  7. Determination of organic acids during the fermentation and cold storage of yogurt.

    Science.gov (United States)

    Fernandez-Garcia, E; McGregor, J U

    1994-10-01

    The objective of the present study was the separation and quantification of orotic, citric, pyruvic, lactic, uric, formic, acetic, propionic, butyric, and hippuric acids in a single isocratic analysis by HPLC. Two methods of extraction were compared: 1) acetonitrile and water and 2) .01N H2SO4. Recoveries of orotic, lactic, acetic, and propionic acids were 90% for both methods. Recoveries of citric, pyruvic, uric, butyric, and hippuric acids were not satisfactory with the acetonitrile method, but were acceptable using the H2SO4 extraction procedure. Yogurts were manufactured under laboratory-scale conditions, and samples were analyzed during fermentation and after storage at 4 degrees C. Samples were analyzed for pH and organic acids. All of the organic acids exhibited varying degrees of increases and decreases during fermentation and storage. Formic and butyric acids were not detected under the conditions of this study.

  8. Simultaneous determination of vanillylmandelic, homovanillic and 5-hydroxyindoleacetic acids in human urine by thin layer chromatography.

    Science.gov (United States)

    Alemany, G; Gamundí, A; Rosselló, C; Rial, R

    1996-01-01

    A TLC method for the simultaneous analysis of vanillylmandelic, homovanillic and 5-hydroxyindole-3-acetic acids in urine is described. The sample is cleaned up through a cyano minicolumn and extracted with diethyl ether. The acids are resolved by high-performance TLC, visualized by Folin Ciocalteau reagent and quantificated by densitometry at 600 nm with beta-(4-hydroxy-3-phenyl) acetic acid as the internal standard.

  9. Functionalized-graphene modified graphite electrode for the selective determination of dopamine in presence of uric acid and ascorbic acid.

    Science.gov (United States)

    Mallesha, Malledevaru; Manjunatha, Revanasiddappa; Nethravathi, C; Suresh, Gurukar Shivappa; Rajamathi, Michael; Melo, Jose Savio; Venkatesha, Thimmappa Venkatarangaiah

    2011-06-01

    Graphene is chemically synthesized by solvothermal reduction of colloidal dispersions of graphite oxide. Graphite electrode is modified with functionalized-graphene for electrochemical applications. Electrochemical characterization of functionalized-graphene modified graphite electrode (FGGE) is carried out by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The behavior of FGGE towards ascorbic acid (AA), dopamine (DA) and uric acid (UA) has been investigated by CV, differential pulse voltammetry (DPV) and chronoamperommetry (CA). The FGGE showed excellent catalytic activity towards electrochemical oxidation of AA, DA and UA compared to that of the bare graphite electrode. The electrochemical oxidation signals of AA, DA and UA are well separated into three distinct peaks with peak potential separation of 193mv, 172mv and 264mV between AA-DA, DA-UA and AA-UA respectively in CV studies and the corresponding peak potential separations in DPV mode are 204mv, 141mv and 345mv. The FGGE is successfully used for the simultaneous detection of AA, DA and UA in their ternary mixture and DA in serum and pharmaceutical samples. The excellent electrocatalytic behavior of FGGE may lead to new applications in electrochemical analysis.

  10. Polymorphism in the fatty acid desaturase genes and diet are important determinants of infant n-3 fatty acid status

    DEFF Research Database (Denmark)

    Harsløf, L.B.S.; Larsen, L.H.; Ritz, C.;

    and polymorphism in the genes that encodes the fatty acid desaturases (FADS) has little effect on DHA-status in adults. It is however unclear to what extent endogenous DHA-synthesis contributes to infant DHA-status. Aim: To investigate the role of diet and FADS polymorphism on DHA-status at 9 months and 3 years....... Methods: This cross-sectional study with Danish infants use data from two prospective studies (EFiON and the SKOT cohort). We measured erythrocyte (RBC) DHA-status at 9 months (n=409) and 3 years (n=176) and genotyped 4 FADS tagSNPs, rs3834458, rs1535, rs174575 and rs174448 (n=401). Information about...... breastfeeding was obtained by questionnaires and fish intake was assessed by 7-day pre-coded food diaries. Results: FADS-genotype, breastfeeding, and fish intake were found to explain 25% of the variation in infant RBC DHA-status (mean±SD: 6.6±1.9% of the fatty acids (FA%)). Breastfeeding was the most important...

  11. HPLC Determination of Ascorbic Acid Using Luminol-Cu(Ⅱ) Chemiluminescence-Application to the Analysis of Juice Beverage

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The chemiluminescence (CL) of luminol-Cu(Ⅱ) was applied to HPLC determination of ascorbic acid, which was separated by a C18 reverse-phase column with a mobile phase of 0.25 mol/L HAc. The eluted ascorbic acid was mixed with 0.3 mmol/L luminol and 0.05 mol/L CuSO4. The light emission from the reaction of Cu(Ⅱ) oxidized ascorbic acid and luminol was detected by a modified luminometer. The detection limit was 3.6×10-6 mol/L for ascorbic acid at a S/N ratio of 3, and the linear calibration range was 2×10-4- 2×10-3 mol/L. The relative standard deviation for 5 replicate injections of 1×10-3 mol/L ascorbic acid was calculated as 4.3 %. The method was successfully applied to determination of ascorbic acid in juice beverage.

  12. Determination of haloacetic acids concentrations in hospital effluent after chlorination by ion chromatography

    Institute of Scientific and Technical Information of China (English)

    SUN Ying-xue; GU Ping

    2007-01-01

    The ion chromatography combined solid phase extraction (SPE) method was developed for the analysis of low concentration haloacetic acids(HAAs),a calss of disinfection by-products formed as a result of chlorination of hospital wastewater. The monitored HAAs included monochloroacetic acid, monobromoacetic acid, dichloroacetic acid, dibromoacetic acid and trichloroacetic acid. The method employed a sodium hydroxide eluent at a flow rate of 0.8 ml/min, electrolytically generated gradients, and suppressed conductivity detection. To analyze the HAAs in real hospital wastewater samples, C18 pretreatment cartridge was utilized to reduce samples' turbidity. Preconcentration with SPE and matrix elimination with treatment cartridges were investigated and were found to be able to obtain acceptable detection limits. Linearity, repeatability and detection limits of the above method were evaluated. The detection limits of monobromoacetic acid and dibromoacetic acid were 2.61 μg/L and 1.30 μg/L respectively, and the other three are ranging from 0.48 to 0.82 μg/L under 25-fold preconcentration. When the above optimization procedure was applied to three hospital wastewater samples with different treatment processes in Tianjin, it was found that the dichloroacetic acid is the major compound, and the growth ratios of the HAAs after disinfection by sodium hypochlorite were 91.28%, 63.61% and 79.50%, respectively.

  13. Study of photorespiration in marine microalgae through the determination of glycolic acid using hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Rigobello-Masini, Marilda; Penteado, José C P; Tiba, Maurício; Masini, Jorge C

    2012-01-01

    Determination of organic acids in intracellular extracts and in the cultivation media of marine microalgae aid investigations about metabolic routes related to assimilation of atmospheric carbon by these organisms, which are known by their role in the carbon dioxide sink. The separation of these acids was investigated by hydrophilic interaction liquid chromatography (HILIC) using isocratic elution with a mobile phase composed of 70:30 v/v acetonitrile/20 mmol/L ammonium acetate buffer (pH 6.8) and detection at 220 nm. HILIC allowed the determinations of glycolic acid, the most important metabolite for the evaluation of the photorespiration process in algae, to be made with better selectivity than that achieved by reversed phase liquid chromatography, but with less detectability. The concentration of glycolic acid was determined in the cultivation media and in intracellular extracts of the algae Tetraselmis gracilis and Phaeodactylum tricornutum submitted to different conditions of aeration: (i) without forced aeration, (ii) aeration with atmospheric air, and (iii) bubbling with N(2). The concentration of glycolic acid had a higher increase as the cultures were aerated with nitrogen, showing higher photorespiratory flux than that occurring in the cultures aerated with atmospheric air.

  14. Quantitative Determination and Comparison of the Surface Binding of Phosphonic Acid, Carboxylic Acid, and Catechol Ligands on TiO2 Nanoparticles.

    Science.gov (United States)

    Zeininger, Lukas; Portilla, Luis; Halik, Marcus; Hirsch, Andreas

    2016-09-12

    The adsorption, desorption, co-adsorption, and exchange behavior of phosphonic acid, carboxylic acid, and catechol derivatives on the surface of titanium oxide (anatase) nanoparticles are investigated. Thermogravimetric analysis provides a facile and fast-track quantitative determination of the wet-chemical monolayer adsorption constants and grafting densities of ten adsorbates, all under neutral pH conditions. This characterization protocol allows straightforward quantification of the relevant thermodynamic data of ligand adsorption and a comparison of ligand adsorption strengths. The reported procedure is proposed as a universal tool and it should be applicable to many other colloidal metal oxide materials. Moreover, the determined values for the adsorption constants and the monolayer grafting densities provide a toolbox for the assessment of the adsorbates' behavior in desorption, exchange, and co-adsorption equilibria. This versatile evaluation procedure will help to identify optimal monolayer-surface combinations and to evaluate critical parameters, such as monolayer robustness, ligand exchange rates, or targeted mixed assembly of functionalities.

  15. Determination of Ascorbic Acid Using a New Oscillating Chemical System of Lactic Acid-Acetone-BrO3--Mn2+-H2SO4

    Institute of Scientific and Technical Information of China (English)

    YANG,Shu-Tao(杨树涛); LIN,Zhi-Xin(林智信); CAI,Ru-Xiu(蔡汝秀); GAN,Nan-Qin(甘南琴)

    2002-01-01

    Analyte pulse perturbation ( APP ) technique was applied to the study of the perturbation of ascorbic acid (AA) on the lactic acid-acetone-BrO3--Mn2+-H2SO4 oscllating reaction, and AA was determined using this new oscillating chemical system. Influence of experimental variables was investigated. The linear range lies between 5.0 × 10-7-5.5 × 10-5 mol/L, and the precision and throughput were quite good (2.43% as RSD,and 8-10 samples/h, respectively). This method was applied to the determination of real samples and the results were satisfactory. Some aspects of the potential mechanism of action of AA on the oscillating systems are discussed.

  16. Simultaneous determination of amino acids and carbohydrates in culture media of Clostridium thermocellum by valve-switching ion chromatography.

    Science.gov (United States)

    Fa, Yun; Yang, Haiyan; Ji, Chengshuai; Cui, He; Zhu, Xinshu; Du, Juan; Gao, Jun

    2013-10-10

    An improved method for the simultaneous determination of 20 amino acids and 7 carbohydrates using one-valve switching after injection, ion chromatography, and integrated pulsed amperometric detection is proposed. The resolution of the amino acids and carbohydrates in the cation trap column was investigated. In addition, parameters including flow liquid type, flow rate, concentration, and valve-switch timing were optimized. The method is time-saving, effective, and accurate for the simultaneous separation of amino acids and carbohydrates, with a mean correlation coefficient of >0.99 and repeatability of 0.5-4.6% for eight replicates. The method was successfully applied in the analysis of amino acids and carbohydrates in aseptic media and in extracellular culture media of three phenotypes of Clostridium thermocellum.

  17. Kinetic Determination of Uric Acid in Human Serum by Using the Uncatalyzed BZ Reaction in Non-equilibrium Steady State

    Institute of Scientific and Technical Information of China (English)

    Ren, Jie; Yang, Wu; Niu, Xiuli; Gao, Jinzhang

    2012-01-01

    A novel kinetic method for determination of uric acid in human serum by means of an uncatalyzed BZ system consisting of potassium bromate and p-hydroxybenzaldehyde (p-HBA) in sulfuric acid medium was proposed, in which the analyte perturbation to the system was recorded close to the bifurcation point. The potential change was directly proportional to the logarithm of concentration of uric acid in the range of 3.73 × 10 8--7.48 × 10-4 mol.L-1 (r=0.9983) with a detection limit of 7.45 × 10-9mol.L-I and a recovery from 98.9% to 101.1%. A comparison between the proposed technique and other methods indicated that results obtained were in agreement with those in clinical detection. In addition, the possible mechanism of action of uric acid on the uncatalyzed BZ reaction was also discussed briefly.

  18. RP-HPLC Determination of vitamins B1, B3, B6, folic acid and B12 in multivitamin tablets

    OpenAIRE

    2005-01-01

    Abstract:Asimple and sensitive reversed-phase, ion-pair HPLC method was developed and validated for the simultaneous determination of B-group vitamins, thiamine chloride hydrochloride (B1), nicotinamide (B3), pyridoxine hydrochloride (B6) and folic acid in Pentovit® coated tablets. The cyanocobalamine (B12) was determined separately, because of its low concentration in the investigated multivitamin preparation. RP-HPLC analysis was performed with a LKB 2150 HPLC system, equipped with a UV/VI...

  19. A novel method for the determination of ascorbic acid and antioxidant capacity in Opuntia ficus indica using in vivo microdialysis.

    Science.gov (United States)

    Pretti, L; Bazzu, G; Serra, P A; Nieddu, G

    2014-03-15

    A simple and rapid method was developed for in vivo simultaneous determination of ascorbic-acid and antioxidant capacity in microdialysates from cladodes of Opuntia ficus-indica (L.) Miller. The method is verified in water-stressed plants, as compared with a well-watered test controls. The microdialysis probe construction and insertion procedure was specifically developed to minimise the tissue trauma of the plant and to obtain optimal dialysis performance. Microdialysis was performed using a flow rate of 3 μL/min and the samples were analysed by HPLC coupled to electrochemical detection of ascorbic-acid and DPPH-determined antioxidant capacity. Our data indicate exponential decay of the concentrations of the analysed compounds as a function of microdialysis sampling time. Water-stressed Opuntia show decreased ascorbic acid levels and increased the others antioxidants.

  20. Simultaneous Determination of Methanol, Ethanol and Formic Acid in Serum and Urine by Headspace GC-FID.

    Science.gov (United States)

    Bursová, Miroslava; Hložek, Tomáš; Čabala, Radomír

    2015-01-01

    A simple, cost-effective headspace gas chromatography (GC) method coupled with GC with flame ionization detection for simultaneous determination of methanol, ethanol and formic acid was developed and validated for clinical and toxicological purposes. Formic acid was derivatized with an excess of isopropanol under acidic conditions to its volatile isopropyl ester while methanol and ethanol remained unchanged. The entire sample preparation procedure is complete within 6 min. The design of the experiment (the face-centered central composite design) was used for finding the optimal conditions for derivatization, headspace sampling and chromatographic separation. The calibration dependences of the method were quadratic in the range from 50 to 5,000 mg/L, with adequate accuracy (89.0-114.4%) and precision (<12%) in the serum. The new method was successfully used for determination of selected analytes in serum samples of intoxicated patients from among those affected by massive methanol poisonings in the Czech Republic in 2012.

  1. Rapid and simple clean-up and derivatizaton procedure for the gas chromatographic determination of acidic drugs in plasma

    NARCIS (Netherlands)

    Roseboom, H.; Hulshoff, A.

    1979-01-01

    A rapid and simple clean-up and derivatization procedure that can be generally applied to the gas chromatographie (GC) determination of acidic drugs of various chemical and therapeutic classes is described. The drugs are extracted from acidified plasma with chloroform containing 5% of isopropanol, w

  2. Determining a Robust D-Optimal Design for Testing for Departure from Additivity in a Mixture of Four Perfluoroalkyl Acids.

    Science.gov (United States)

    Our objective is to determine an optimal experimental design for a mixture of perfluoroalkyl acids (PFAAs) that is robust to the assumption of additivity. PFAAs are widely used in consumer products and industrial applications. The presence and persistence of PFAAs, especially in ...

  3. Determination of urinary 18 beta-glycyrrhetinic acid by gas chromatography and its clinical application in man

    NARCIS (Netherlands)

    Guillaume, CPF; van der Molen, JC; Kerstens, MN; Dullaart, RPF; Wolthers, BG

    1999-01-01

    A sensitive and quantitative gas chromatographic assay for the determination of 18 beta-glycyrrhetinic acid (18 beta-GA), the main metabolite of glycyrrhizin after oral licorice consumption in human urine, has been developed and validated. For the extraction of 18 beta-GA from urine two Sep-Pak C-18

  4. DETERMINATION OF ION EXCHANGE EQUILIBRIUM CONSTANTS FOR THE WEAK ACID CATION AND THE WEAK BASE ANION EXCHANGE RESINS

    Institute of Scientific and Technical Information of China (English)

    TAOZuyi; WANGChangshou

    1992-01-01

    The general procedure based on the potentiometric titration has developed.According to the procedure,the rational equilibrium constants of the ion exchange reactions RH/Na,RH/Ca,RH/Sr,RH/Ba for the weak acid cation exchange resin D725 and ROH/Cl for the weak base anion exchange resin D705 have been determined.

  5. Gas chromatographic determination of acid herbicides in surface water samples with electron-capture detection and mass spectrometric confirmation

    NARCIS (Netherlands)

    Vink, M.; Poll, J.M. van der

    1996-01-01

    The development of a multi-residue method for the determination of eight polar acidic herbicides (MCPA, MCPB, mecoprop, 2,4-D, dichlorprop, bentazone, dicamba and dikegulac) in surface water is described. The method involves an off-line solid-phase extraction (SPE) procedure prior to instrumental an

  6. Impedimetric test for rapid determination of performic acid (PFA biocidal activity toward Echerichia coli

    Directory of Open Access Journals (Sweden)

    Małgorzata Lasik

    2013-12-01

    Full Text Available   Background. Performic acid has recently become available on a commercial scale for potential use in waste-water disinfection and can become an innovative biocide for various purposes in food processing. The aim of our study was: 1 to investigate the antimicrobial resistance of performic acid as high active and non toxic chemical disinfectant against Escherichi coli (hygiene indicator test  microorganism used in industrial micro- biology and 2 to evaluate the electrical impedance measurement method usefulness for fast and high precise test of antibacterial activity. Material and methods. Four types of antimicrobial disinfectants (commercial 35% hydrogen peroxide, 1% performic acid, 35% hydrogen peroxide and 15% formic acid were tested against Escherichia coli as hygiene indicator test microorganism. By evaluating the biocidal activity of selected disinfectants two methods were compared: electrical impedance measurement and classical serial dilution method with turbidity effect. Results.  It was stated that the performic acid expressed the highest antibacterial activity in comparison to other tested peroxide disinfectants: commercial 35% hydrogen peroxide solution and components required for performic acid production: 35% hydrogen peroxide solution with stabilizers and 15% formic acid solution with stabilizers. It was demonstrated that the proposed alternative microbiology method of electrical imped- ance measurement facilitates a rapidly and more precise analyses of the intensity of disinfectants inhibition effect. Conclusions. It can be postulated that both, the performic acid disinfectants as well as the impedimetric method can be a good advantage in the industrial microbiology.  

  7. New insight into the SSC8 genetic determination of fatty acid composition in pigs

    NARCIS (Netherlands)

    Revilla, M.; Ramayo-Caldas, Y.; Castello, A.; Corominas, J.; Puig-Oliveras, A.; Ibanez-Escriche, N.; Munoz, M.; Ballester, M.; Folch, J.M.

    2014-01-01

    BACKGROUND: Fat content and fatty acid composition in swine are becoming increasingly studied because of their effect on sensory and nutritional quality of meat. A QTL (quantitative trait locus) for fatty acid composition in backfat was previously detected on porcine chromosome 8 (SSC8) in an Iberia

  8. [Determination of gambogic acid in Gamboge by non-aqueous capillary electrophoresis].

    Science.gov (United States)

    Ou, Wanlu; Li, Yujuan; Shi, Dongdong; Qu, Feng

    2015-02-01

    Gambogic acid (GA), a kind of caged xanthones, has low solubility in water. A non-aqueous capillary electrophoresis (NACE) was established for the determination of GA in Gamboge based on the optimized conditions. The effect of 20% - 60% methanol or acetonitrile spiked in running solution was investigated. The effects of compositions, concentration, pH, additives like β-cyclodextrin in running buffer were thoroughly studied. Applied voltage and applied temperature were also observed. Optimal electrophoretic conditions were as follows: 20 mmol/L sodium borohydride solution (pH 9. 86) containing 40% (v/v) acetonitrile, 10 mmol/L β-cyclodextrin as running buffer, applied voltage of 10 kV, capillary temperature of 30 °C and detection wavelength of 280 nm. The calibration curve had good linearity in the range of 2-2 000 mg/L with the correlation coefficient of 0. 999 6. The limit of quantification (S/N= 3) of the method was 2 mg/L. The quantifications of GA in Gamboge from different producing places including Vietnam, Thailand, Burma, India were 1. 67-472.40 mg/g with the RSD (n= 3) of 1.12% -2.60%. The content of Gamboge from Vietnam is obviously low while the others are high. The recoveries of GA spiked in real samples ranged from 95. 2% to 105. 6%. The method of NACE is simple, efficient and of good reproducibility, can be served as a novel reference to identify and control the quality of Gamboge.

  9. Determination of primary amino acids in wines by high performance liquid magneto-chromatography.

    Science.gov (United States)

    Barrado, E; Rodriguez, J A; Castrillejo, Y

    2009-05-15

    Eight amino acids (ethanolamine, glycine, alanine, beta-aminobutyric acid, leucine, methionine, histidine and asparagine) were identified and quantified in Spanish wines by high performance liquid magneto-chromatography (HPLMC) with UV-V spectrophotometry. For this method, the amino acids are first complexed with mono(1,10-phenanthroline)-Cu(II) to confer them paramagnetic properties, and then separated by application of a low magnetic field intensity (5.5 mT) to the stationary phase contained in the chromatographic column. Principal components analysis of the results obtained grouped together the wine samples according to their denomination of origin: "Ribera del Duero", "Rueda" or "Rioja" (Spain). Through cluster analysis, a series of correlations was also observed among certain amino acids, and between these groupings and the type of wine. These clusters were found to reflect the role played by the amino acids as primary or secondary nutrients for the bacteria involved in alcoholic and malolactic fermentation.

  10. Molecular Determinants of the Response of Tumor Cells to Boswellic Acids

    Directory of Open Access Journals (Sweden)

    Thomas Efferth

    2011-08-01

    Full Text Available Frankincense (Boswellia serrata, B. carterii is used as traditional remedy to treat inflammatory diseases. The molecular effects of the active ingredients, the boswellic acids, on the immune system have previously been studied and verified in several clinical studies. Boswellic acids also inhibit cancer cell growth in vitro and in vivo. The molecular basis of the cytotoxicity of boswellic acids is, however, not fully understood as yet. By mRNA-based microarray, COMPARE, and hierarchical cluster analyses, we identified a panel of genes from diverse functional groups, which were significantly associated with sensitivity or resistance of a- or b-boswellic acids, such as transcription factors, signal transducers, growth regulating genes, genes involved in RNA and protein metabolism and others. This indicates that boswellic acids exert profound cytotoxicity on cancer cells by a multiplicity of molecular mechanisms.

  11. Molecular Determinants of the Response of Tumor Cells to Boswellic Acids

    Science.gov (United States)

    Eichhorn, Tolga; Greten, Henry Johannes; Efferth, Thomas

    2011-01-01

    Frankincense (Boswellia serrata, B. carterii) is used as traditional remedy to treat inflammatory diseases. The molecular effects of the active ingredients, the boswellic acids, on the immune system have previously been studied and verified in several clinical studies. Boswellic acids also inhibit cancer cell growth in vitro and in vivo. The molecular basis of the cytotoxicity of boswellic acids is, however, not fully understood as yet. By mRNA-based microarray, COMPARE, and hierarchical cluster analyses, we identified a panel of genes from diverse functional groups, which were significantly associated with sensitivity or resistance of α- or β-boswellic acids, such as transcription factors, signal transducers, growth regulating genes, genes involved in RNA and protein metabolism and others. This indicates that boswellic acids exert profound cytotoxicity on cancer cells by a multiplicity of molecular mechanisms.

  12. Determination of vanillylmandelic acid, vanillactic acid, and homovanillic acid in dried urine on filter-paper discs by high-performance liquid chromatography with coulometric electrochemical detection for neuroblastoma screening.

    Science.gov (United States)

    Kinoshita, Y; Yamada, S; Haraguchi, K; Takayanagi, T; Mori, Y; Takahashi, T; Haruki, E

    1988-11-01

    We report a method for determination of vanillylmandelic acid, vanillactic acid, and homovanillic acid by high-performance liquid chromatography (HPLC), with coulometric electrochemical detection, for mass screening of neuroblastoma. Urine samples were collected on filter paper, dried, and then pretreated. The chromatographic procedure is reliable and fast, allowing for a large sample throughput for routine screening. Intricate extraction procedures and centrifugal separation are unnecessary. Screening for neuroblastoma by HPLC is rapidly gaining acceptance in Japan, and our method is being used at many screening centers. Of 26,571 infants screened in one year in Yokohama City, our method detected five with neuroblastoma.

  13. Total dietary fiber determined as neutral sugar residues, uronic acid residues, and Klason lignin (the Uppsala method): collaborative study.

    Science.gov (United States)

    Theander, O; Aman, P; Westerlund, E; Andersson, R; Pettersson, D

    1995-01-01

    A joint AOAC/American Association of Cereal Chemists (AACC) collaborative study was conducted to determine by the Uppsala method the dietary fiber content and its composition in various foods. The method includes preparation of a residue by treatment with thermostable alpha-amylase and amyloglucosidase and then ethanol precipitation of solubilized dietary fiber components while leaving low-molecular weight carbohydrates in solution. After acid hydrolysis of residue, neutral polysaccharide residues are determined as alditol acetates by gas-liquid chromatography, uronic acid residues are determined by colorimetry, and ash-free acid-insoluble residue (Klason lignin) is determined gravimetrically. Total dietary fiber, including enzyme-resistant starch, is calculated as the sum of nonstarch polysaccharide residues and Klason lignin. Nine laboratories completed the study, analyzing in duplicate 8 unknown dried products that included 4 cereal products, green peas, potato fiber, carrots, and apples. Total dietary fiber contents of products tested ranged from 4.6 to 84.3%, with an average RSDR value of 8.4% (range, 4.8-11.1%). Total neutral polysaccharide residues ranged from 3.8 to 64.1%, with an average RSDR value of 7.5% (range, 5.4-10.5%). Individual neutral sugars (rhamnose, arabinose, xylose, mannose, galactose, and glucose) and uronic acid residues present at more than 1% generally had good RSDR values (3.3-22.8%), whereas, as expected for Klason lignin, only the wheat bran sample with a high content (16%) had an excellent RSDR value (5.0%). The gas chromatographic-colorimetric-gravimetric method (Uppsala method) for determination of total dietary fiber (as neutral sugar residues, uronic acid residues, and Klason lignin) has been adopted first action by AOAC INTERNATIONAL.

  14. Simultaneous determination of protocatechuic acid, syringin, chlorogenic acid, caffeic acid, liriodendrin and isofraxidin in Acanthopanax senticosus Harms by HPLC-DAD.

    Science.gov (United States)

    Li, Qing; Jia, Ying; Xu, Liang; Wang, Xiaohui; Shen, Zhenduo; Liu, Yulei; Bi, Kaishun

    2006-03-01

    A high performance liquid chromatography (HPLC) method was developed for the first time to quantify simultaneously the six major active ingredients in Acanthopanax senticosus (Rupr. et Maxim.) Harms, namely protocatechuic acid, syringin, chlorogenic acid, caffeic acid, liriodendrin and isofraxidin. The analysis was performed by a reverse phase gradient elution with an aqueous mobile phase (containing 0.05% phosphoric acid) modified by acetonitrile and diode-array multiple-wavelength UV detector (DAD). Six regression equations showed good linear relationships between the peak area of each marker and concentration. The recoveries of the markers listed above were 92.3%, 93.9%, 90.3%, 93.1%, 94.3% and 90.7%, respectively. The relative standard deviation of intra-day and inter-day were less than 2.7% and 3.1%, respectively. This method was validated for specificity, accuracy, precision and limits of quantification. Medicinal materials of ten commercial brands were analyzed and found to contain different amounts of the six bioactive markers. The method developed can be used for the quality control of Acanthopanax senticosus (Rupr. et Maxim.) Harms.

  15. Determination and stereochemistry of proteinogenic and non-proteinogenic amino acids in Saudi Arabian date fruits.

    Science.gov (United States)

    Ali, Hatem Salama Mohamed; Alhaj, Omar Amin; Al-Khalifa, Abdulrahman Saleh; Brückner, Hans

    2014-09-01

    Whereas an abundance of literature is available on the occurrence of common proteinogenic amino acids (AAs) in edible fruits of the date palm (Phoenix dactylifera L.), recent reports on non-proteinogenic (non-coded) AAs and amino components are scarce. With emphasis on these components we have analyzed total hydrolysates of twelve cultivars of date fruits using automated ion-exchange chromatography, HPLC employing a fluorescent aminoquinolyl label, and GC-MS of total hydrolysates using the chiral stationary phases Chirasil(®)-L-Val and Lipodex(®) E. Besides common proteinogenic AAs, relatively large amounts of the following non-proteinogenic amino acids were detected: (2S,5R)-5-hydroxypipecolic acid (1.4-4.0 g/kg dry matter, DM), 1-aminocyclopropane-1-carboxylic acid (1.3-2.6 g/kg DM), γ-amino-n-butyric acid (0.5-1.2 g/kg DM), (2S,4R)-4-hydroxyproline (130-230 mg/kg DM), L-pipecolic acid (40-140 mg/kg DM), and 2-aminoethanol (40-160 mg/kg DM) as well as low or trace amounts (amino acids in date fruits is briefly addressed.

  16. Quantitative determination of uric acid using CdTe nanoparticles as fluorescence probes.

    Science.gov (United States)

    Jin, Dongri; Seo, Min-Ho; Huy, Bui The; Pham, Quoc-Thai; Conte, Maxwell L; Thangadurai, Daniel; Lee, Yong-Ill

    2016-03-15

    A convenient enzymatic optical method for uric acid detection was developed based on the fluorescence quenching of ligand-capped CdTe nanoparticles by H2O2 which was generated from the enzymatic reaction of uric acid. The interactions between the CdTe nanoparticles capped with different ligands (glutathione, 3-mercaptopropionic acid, and thioglycerol) and H2O2 were investigated. The fluorescence quenching studies of GSH-capped CdTe nanoparticles demonstrated an excellent sensitivity to H2O2. The effects of uric acid, uricase and H2O2 on the fluorescence intensity of CdTe nanoparticles were also explored. The detection conditions, reaction time, pH value, incubation period and the concentration of uricase and uric acid were optimized. The detection limit of uric acid was found to be 0.10 µM and the linear range was 0.22-6 µM under the optimized experimental conditions. These results typify that CdTe nanoparticles could be used as a fluorescent probe for uric acid detection.

  17. The EZ:Faast family of amino acid analysis kits: application of the GC-FID kit for rapid determination of plasma tryptophan and other amino acids.

    Science.gov (United States)

    Badawy, Abdulla A-B

    2012-01-01

    Plasma tryptophan (Trp) and other amino acids (AA) can be determined rapidly by gas (GC) or liquid (LC) chromatography using the Phenomenex EZ:Faast(™) family of kits. Three kits are available: (1) GC-FID or -NPD, (2) GC-MS, (3) LC-MS. The two GC kits can determine 32 AA, whereas the LC-MS can determine five additional AA. All three kits, however, share the same experimental procedure up to and including the preparation of derivatised AA. The method is based on solid-phase extraction (SPE), thus saving time on prior removal of plasma or other proteins and interfering substances, and can be applied to other body fluids and experimental media and to supernatants of extracts of solid material. Briefly, SPE is performed using a proprietary cation-exchange mechanism. The acid solution of the internal standard ensures that the free amino acids are in an anionic form suitable for cationic binding. The alkaline nature of the elution medium ensures that the AA cations are released prior to derivatisation. The latter involves production of chloroformate derivatives of both the amino and carboxylic acid groups. With experience, six plasma samples can be so processed within 12 min. The shortest analytical run is FID/NPD kit. Despite its many steps, the procedure becomes second nature and an enjoyable task. I have now used the GC-FID kit with manual injection to process >1,600 plasma and other samples. Limit of detection of AA is 1 μM or less. The procedure has been validated and optimised for Trp and its main five brain uptake competitors.

  18. DETERMINATION OF GAMMA - AMINOBUTYRIC ACID BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY

    Directory of Open Access Journals (Sweden)

    D. Qujeq

    1998-08-01

    Full Text Available Gamma-aminobutyric acid is the main inhibitory amino acid neurotransmitter in several areas of the brain. Measurement of gamma-aminobutyric acid in the brain will help elucidate its metabolic rote and diagnostic value. The liquid chromatography (LC system consisted of a delivery pump. Male rats (150-250g were used in this study. The brain was rapidly removed from decapitated animals. Trie chromatograms showed satisfactory resolution and symmetrical peak shapes, both with the standard and tissue extracts. the retention lime was 4.60 min. it was constant in repeated analyses and exactly the same for the standard and tissue samples.

  19. EFFECT OF SURFACTANT SDS ON DETERMINATION OF NUCLEIC ACID WITH TERBIUM (III)FLUO

    Institute of Scientific and Technical Information of China (English)

    WuHui; WanYu

    2002-01-01

    The effect of an anionic surfactant(sodium dodecylsulfate.SDS)on the fluorescence properties of nucleic acid with terbium(III)is studied.Results show that ri-bonucleir acid (RNA)presents fluorescence reaction with Tb(III)directly.but deoxyribonucleic acid(DNA)pre-sents similar fluorescence reaction only after its denatura-tion.In the presence of SDS ,the fluorescence intensity is 4.0 times and 3.5 times greater than that of DNA and RNA without SDS.

  20. A high-performance liquid chromatography (HPLC) method for determination of chlorogenic acid and emodin in Yinhuang Jiangzhi Tea

    Institute of Scientific and Technical Information of China (English)

    Jie Shen; Xiang-Hui Xu

    2016-01-01

    Objective:To establish a high-performance liquid chromatography (HPLC) method for the determination of chlorogenic acid and emodin in Yinhuang Jiangzhi tea.Methods:The contents of chlorogenic acid and emodin in Yinhuang Jiangzhi tea were determined with Diamonsil C18 column by eluting with acetonitrile: 0.4% phosphoric acid in water (13:87) and methanol: 0.1% phosphoricacid in water (80:20), with detection at 327 nm and 254 nm respectively. The flow rate was 1.0 mL/min, and the column temperature was 30℃.Results:The correlation between injection volume and peak area of chlorogenic acid and emodin was Y=17.955X-0.2848 (R=0.9999, 0.041-0.41 μg) and Y=33.975X+186.36 (R=0.9995, 0.0395-0.395 μg), respectively. The mean recovery of chlorogenic acid and emodin was 100.38%(RSD=2.34%,n=9) and 101.21% (RSD=2.59%,n=9), respectively.Conclusions: The established HPLC method is relatively simple, accurate, and specific, and can be used for the quality control of Yinhuang Jiangzhi tea.

  1. [Simultaneous determination of 16 organic acids in feed additives by on-line enrichment and ion chromatography-mass spectrometry].

    Science.gov (United States)

    Xiong, Zhiyu; Dong, Ying; Zhou, Hongbin; Yu, Yang; Li, Jing; Sun, Li

    2014-02-01

    A novel analytical method for simultaneous determination of sixteen organic acids by on-line enrichment and ion chromatography-mass spectrometry (IC-MS) was developed. Online enrichment and separation of the organic acids were performed by ion chromatography on a homemade enrichment column and a homemade separation column. The qualitative and quantitative analyses of the organic acids were performed by mass spectrometry in selected ion monitoring (SIM) mode on the basis of atmospheric pressure chemical ionization (APCI) source in negative mode. The sample of 200 microL was injected for the analysis, and the on-line enrichment time was 3 min. The sodium hydroxide solution was used as a gradient elution system. The two columns made it possible to have a low limit of detection due to the good enrichment and separation capability. The sixteen organic acids were separated completely within 30 min. All curves showed good linearity within the test concentration ranges. The limits of detection (LODs) were between 0.01 and 0.22 mg/L, and the average recoveries were between 70.6% and 110.8%. The relative standard deviations (RSDs) were less than 6.3%. The results indicate that this method is simple, rapid, sensitive and accurate for the determination of the organic acids in feed additives.

  2. Electrochemical Preparation of a Molecularly Imprinted Polypyrrole-modified Pencil Graphite Electrode for Determination of Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    Yücel Sahin

    2008-09-01

    Full Text Available A molecularly imprinted polymer (MIP polypyrrole (PPy-based film was fabricated for the determination of ascorbic acid. The film was prepared by incorporation of a template molecule (ascorbic acid during the electropolymerization of pyrrole onto a pencil graphite electrode (PGE in aqueous solution using a cyclic voltammetry method. The performance of the imprinted and non-imprinted (NIP films was evaluated by differential pulse voltammetry (DPV. The effect of pH, monomer and template concentrations, electropolymerization cycles and interferents on the performance of the MIP electrode was investigated and optimized. The molecularly imprinted film exhibited a high selectivity and sensitivity toward ascorbic acid. The DPV peak current showed a linear dependence on the ascorbic acid concentration and a linear calibration curve was obtained in the range of 0.25 to 7.0 mM of ascorbic acid with a correlation coefficient of 0.9946. The detection limit (3σ was determined as 7.4x10-5 M (S/N=3. The molecularly-imprinted polypyrrole-modified pencil graphite electrode showed a stable and reproducible response, without any influence of interferents commonly existing in pharmaceutical samples. The proposed method is simple and quick. The PPy electrodes have a low response time, good mechanical stability and are disposable simple to construct.

  3. Determination of Gallic Acid by Flow Injection Analysis Based on LuminoI-AgNO3-Ag NPs Chemiluminescence System

    Institute of Scientific and Technical Information of China (English)

    李世凤; 孙惠敏; 王东; 钱莉; 朱燕; 陶善军

    2012-01-01

    A novel flow injection procedure has been developed for the determination of gallic acid based on the en- hancement function for luminol-AgNO3-Ag NPs chemiluminescence (CL) system by gallic acid. The enhancement mechanism was proposed for the reinforcing effect of the gallic acid on the CL system. The UV-vis absorption spectrum and CL emission spectrum were applied to confirm the mechanism. The method is simple, rapid and sen- sitive with a detection limit of 5 × 10^-10 g.mL-l and a linear range of 8.0 × 10^-10- 1.0 × 10-7 g.mL-1. The relative standard deviation (RSD) is 1.3% for eleven measurements of 5 × 10^-8 g-mL-1 gallic acid. The method has been successfully applied to the determination of gallic acid in Chinese proprietary medicine--Jianmin Yanhou tablets and synthesized samples.

  4. Simultaneous determination of 12, 13-dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture by high performance liquid chromatography

    Institute of Scientific and Technical Information of China (English)

    Zhi-Sheng Xie; Xin-Jun Xu; Chun-Yan Xie; Jie-Yun Huang; Mei Yang; Rui-Ming Li; Xiao Chen

    2011-01-01

    A reversed phase high performance liquid chromatography (HPLC) method was established for the simultaneous determination of 12, 13-dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture. A Grace Apollo Cl8 column (250 mm × 4.6 mm, 5 μm) was used as the stationary phase and the mobile phase was composed of acetonitrile and aqueous phosphoric acid (0.2%, v/v). Gradient elution was carried out at the flow rate of 1.0 mL/min and the column temperature was 30 ℃. An ultraviolet (UV) detector was used with a selected wavelength of 240 nm. Calibration curves were linear within the concentration range of 4.6-45.75 μg/mL for 12, 13-dihydroxyeuparin (r〉0.9999) and 106.9-1068.9μg/mL for glycyrrhizic acid (r〉0.9999), respectively. Recoveries were 102.18% for 12, 13-dihydroxyeuparin and 101.17% for glycyrrhizic acid. The method developed could be applied to the simultaneous determination of 12, 13- dihydroxyeuparin and glycyrrhizic acid in Yanyanfang mixture.

  5. Tissue distribution study of salvianolic acid B long-circulating liposomes in mice by UPLC-MS/MS determination.

    Science.gov (United States)

    Pi, Jiaxin; Liu, Zhidong; Shu, Lexin; Li, Lin; Wang, Ying; Li, Nan; Li, Jiawei

    2015-01-01

    In targeting delivery system research on salvianolic acid B, it's vital but hard to evaluate the tissue distribution for its low concentrations in tissues. So the simple, rapid, selective and sensitive UPLC-MS/MS method was provided hereby to determine the concentration of salvianolic acid B in mice tissues after intravenous administration of salvianolic acid B injections, conventional liposomes and long-circulating liposomes. The UPLC was conducted by a C(18) column with a gradient mobile phase consisting of acetonitrile and water containing 0.1% formic acid. The tandem mass spectrometry was operated in negative-electrospray ionization selected-reaction-monitoring mode, and the optimized characteristic precursor to product ion transition m/z 717.3→519.1 was selected. The biosamples were homogenized and treated with a protein precipitation, which led to an acceptable matrix effect and extraction recovery. The linear calibration curves were plotted in the given concentration ranges. The intra-day and inter-day precisions were less than 13.9% and the accuracies were in the range of 86.3-109.2%. The tissue distribution results determined by UPLC-MS/MS we developed showed that the conventional and long-circulating liposomes we made had succeeded in prolonging the retention time and increasing the level of salvianolic acid B in certain distribution tissues such as liver, kidney and brain.

  6. 灵芝中灵芝酸的测定研究%Determination of Ganoderma Lucidum Acid by HPLC

    Institute of Scientific and Technical Information of China (English)

    孙金旭

    2015-01-01

    The HPLC determination method for the determination of Ganoderma lucidum acid was established. The result showed that the maximum standard deviation of cholesterol content was 1.36%under this method for determination and Cholesterol content displayed an excellent linear relationship , the standard curve equation was Y=625.71x+82.857(R=0.998 2). The spike recoveries for cholesterol were between 97.04%and 102.64%, the method was feasibility and accurate for using to determine Ganoderma lucidum acid, the average contents of Ganoderma lucidum acid was 1.03 mg/g by HPLC determination.%利用HPLC法测定灵芝中灵芝酸含量的方法,此方法测定灵芝中灵芝酸含量重复性试验最大标准偏差为1.36%,峰面积与灵芝酸标品线性关系良好,标准曲线方程为Y=625.71x+82.857(R=0.9982),加标回收率在97.04%~102.64%之间,此方法用于灵芝中灵芝酸含量准确、可行;经测定灵芝中灵芝酸为含量1.03 mg/g。

  7. Spectrophotometric determination of copper(II) in pharmaceutical, biological and water samples by 4-(2'-benzothiazolylazo)-salicylic acid

    Science.gov (United States)

    Hashem, E. Y.; Seleim, M. M.; El-Zohry, A. M.

    2011-09-01

    A highly sensitive method is proposed to determine copper(II) ions by forming a stable complex through their interaction with 4-(2'-benzothiazolylazo)-salicylic acid (BTAS) at room temperature and pH of about 5.0. The complex gave a maximum absorption at λ = 485 nm with a molar absorptivity coefficient of 2.35·104 l/(mol·cm). The linear range for the copper determination is 0.63-5.04 mg/l. The method can be applied to determine copper ions in different biological specimens like some drugs and water samples.

  8. Design of experiments for amino acid extraction from tobacco leaves and their subsequent determination by capillary zone electrophoresis.

    Science.gov (United States)

    Hodek, Ondřej; Křížek, Tomáš; Coufal, Pavel; Ryšlavá, Helena

    2017-01-13

    In this study, we optimized a method for the determination of free amino acids in Nicotiana tabacum leaves. Capillary electrophoresis with contactless conductivity detector was used for the separation of 20 proteinogenic amino acids in acidic background electrolyte. Subsequently, the conditions of extraction with HCl were optimized for the highest extraction yield of the amino acids because sample treatment of plant materials brings some specific challenges. Central composite face-centered design with fractional factorial design was used in order to evaluate the significance of selected factors (HCl volume, HCl concentration, sonication, shaking) on the extraction process. In addition, the composite design helped us to find the optimal values for each factor using the response surface method. The limits of detection and limits of quantification for the 20 proteinogenic amino acids were found to be in the order of 10(-5) and 10(-4) mol l(-1), respectively. Addition of acetonitrile to the sample was tested as a method commonly used to decrease limits of detection. Ambiguous results of this experiment pointed out some features of plant extract samples, which often required specific approaches. Suitability of the method for metabolomic studies was tested by analysis of a real sample, in which all amino acids, except for L-methionine and L-cysteine, were successfully detected. The optimized extraction process together with the capillary electrophoresis method can be used for the determination of proteinogenic amino acids in plant materials. The resulting inexpensive, simple, and robust method is well suited for various metabolomic studies in plants. As such, the method represents a valuable tool for research and practical application in the fields of biology, biochemistry, and agriculture.

  9. Determining and surveying the role of carnitine and folic acid to decrease fatigue in β-thalassemia minor subjects.

    Science.gov (United States)

    Tabei, Seyed Mohammad Bagher; Mazloom, Maryam; Shahriari, Mahdi; Zareifar, Soheila; Azimi, Ali; Hadaegh, Amirhossein; Karimi, Mehran

    2013-11-01

    Beta-thalassemia minor (BTM) patients usually experience fatigue, bone pain complaint, and muscle weakness. Carnitine is an essential protein for transportation of long-chain fatty acids to the matrix for beta-oxidation. BTM patients have abnormally low plasma carnitine concentrations, which results in deficient ATP production. Carnitine and folic acid together may have a role in preventing bone pain complaint and fatigue in these patients. The aim of this study is to determine the effect of carnitine and folic acid supplementation in subjects with BTM. Seventy three BTM (mean age 11.06 ± 5.46 years) and 23 healthy controls (mean age 8.48 ± 3.78 years) were enrolled in the study. Fasting blood was drawn to determine baseline free and total carnitine levels, red blood cell folate concentration, and hemoglobin level. BTM were divided into three groups and received different types of supplementation for 3 months: Group 1, 50 mg/kg/day carnitine; Group 2, 50 mg/kg/day carnitine plus 1 mg/day folic acid; and Group 3, 1 mg/day folic acid. Controls did not receive supplementation. Laboratory parameters were again evaluated after 3 months' supplementation. A detailed quality of life questionnaire was designed to investigate muscle symptoms before and after supplementation. Free and total plasma carnitine concentration and hemoglobin levels in BTM subjects increased significantly after carnitine supplementation (P carnitine. Red blood cell folate level increased after folic acid supplementation. Carnitine and folic acid supplementation resulted in a decrease in bone pain complaint and muscle weakness in cases with β-thalassemia minor.

  10. Disposable biosensor based on cathodic electrochemiluminescence of tris(2,2-bipyridine)ruthenium(II) for uric acid determination

    Energy Technology Data Exchange (ETDEWEB)

    Ballesta-Claver, J.; Rodríguez-Gómez, R. [ECsens, Department of Analytical Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, E-18071 Granada (Spain); Capitán-Vallvey, L.F., E-mail: lcapitan@ugr.es [ECsens, Department of Analytical Chemistry, Campus Fuentenueva, Faculty of Sciences, University of Granada, E-18071 Granada (Spain)

    2013-04-03

    Highlights: ► Cathodic ECL offers conventional and non-aggressive analysis conditions. ► The ECL hydrogen peroxide/ruthenium complex system for uric acid determination is novel. ► The ruthenium complex is electrochemically immobilized on graphite screen-printed electrodes. ► The quantification of the uric acid is based on a Stern–Volmer type equation. ► The use of the cathodic ECL working methodology reduces interferences during analysis. -- Abstract: A new method for uric acid (UA) determination based on the quenching of the cathodic ECL of the tris(2,2-bipyridine)ruthenium(II)–uricase system is described. The biosensor is based on a double-layer design containing first tris(2,2-bipyridine)ruthenium(II) (Ru(bpy){sub 3}{sup 2+}) electrochemically immobilized on graphite screen-printed cells and uricase in chitosan as a second layer. The uric acid biosensing is based on the ECL quenching produced by uric acid over the cathodic ECL caused by immobilized Ru(bpy){sub 3}{sup 2+} in the presence of uricase. The use of a −1.1 V pulse for 1 s with a dwelling time of 10 s makes it possible to estimate the initial enzymatic rate, which is used as the analytical signal. The Stern–Volmer type calibration function shows a dynamic range from 1.0 × 10{sup −5} to 1.0 × 10{sup −3} M with a limit of detection of 3.1 × 10{sup −6} M and an accuracy of 13.6% (1.0 × 10{sup −4} M, n = 5) as relative standard deviation. Satisfactory results were obtained for urine samples, creating an affordable alternative for uric acid determination.

  11. Comparison of acid ethanol extraction and acid gel filtration prior to IGF-I and IGF-II radioimmunoassays; Improvement of determinations in acid ethanol extracts by the use of truncated IGF-I as radioligand

    Energy Technology Data Exchange (ETDEWEB)

    Bang, P.; Eriksson, U.; Wivall, I.-L.; Hall, K. (Department of Endocrinology, Karolinska Institute, Stockholm (Sweden)); Sara, V. (Department of Pathology, Karolinska Institute, Stockholm (Sweden))

    1991-01-01

    Insulin-like growth factor binding proteins interfere in the IGF-I and -II radioimmunoassays. In an attempt to overcome this problem, we have compared the use of truncated IGF-I, with reduced IGFBP affinity, and IGF-I as radioligands for IGF-I RIA measurements in serum separated by acid gel filtration or acid ethanol extraction followed by cryo-precipitation. With truncated IGF-I as radioligand the IGF-I measurements in acid gel filtrates and acid ethanol extracts were significantly correlated in healthy subjects (N=42, r=0.91, p<0.001) and in patients with acromegaly (N=10, r=0.85, p<0.01), GH deficiency (N=10, r=0.88, p<0.001) or Type I diabetes mellitus (N=10, r=0.90, p<0.001). In contrast, the IGF-I concentrations in acid ethanol extracts determined with IGF-I as radioligand did not correlate with those in acid gel filtrates using truncated IGF-I radioligand in patients with acromegaly (r=0.61, NS) or GH deficiency (r=0.46, NS). In the latter group the mean IGF-I concentrations measured in acid ethanol extracts were erroneously elevated by 112%. Low-affinity antibodies used for IGF-II RIA determinations failed to give reliable results in acid ethanol extracts from patients with Type I diabetes mellitus or GH deficiency. In conclusion, erroneously high IGF-I concentrations owing to binding of the radioligand to IGFBPs not completely removed by acid ethanol extraction can be avoided by the use of truncated IGF-I as radioligand. (author).

  12. 饲用酸化剂中甲酸、乙酸、丙酸、乳酸、柠檬酸的同步测定%Determination of formic acid, acetic acid, propionic acid, lactic acid, citric acid in feed acidifier

    Institute of Scientific and Technical Information of China (English)

    索德成; 李兰; 樊霞

    2012-01-01

    A method of the simultaneous determination of the contents of formic acid, acetic acid, propionic acid, lactic acid, citric acid in feed acidifier by HPLC was established. The separation was performed on Grom-Silorg acid(250 mm×4.6 mm, 5 μm) with the mobile phase of hydrochloric acid solution (pH 2.5)/The detection wave length was 210 nm.The flow rate was 1,0 ml/min and the column temperature was 30 ℃.Good linearities of five acid were showed. The average recoveries were greater than 85% respectively, RSD was less than 10.0%.The result of real sample have been shown: the method was simple, rapid and reliable for the simultaneous determination of formic acid, acetic acid, propionic acid, lactic acid, citric acid in organic acids.%实验建立利用高效液相色谱同时测定饲用酸化剂中甲酸、乙酸、丙酸、乳酸、柠檬酸含量的方法.采用Grom-Sil org acid柱(250 mm×2.1 mm,5μm)进行分析.流动相为pH值2.5磷酸水溶液;流速为1.0 ml/min;检测波长为210 nm;柱温为30℃.在此色谱条件下,5种有机酸分离良好.平均回收率均大于85%,RSD小于10.0%.对实际样品的检测结果表明:该方法操作简便易行,准确可靠.

  13. Determination of 18 beta-glycyrrhetinic acid in human serum using the fully automated ALCA-system.

    Science.gov (United States)

    Heilmann, P; Heide, J; Schöneshöfer, M

    1997-07-01

    We report a method for the determination of 18 beta-glycyrrhetinic acid (glycyrrhetinic acid) in human serum using the ALCA-system. The technology of the ALCA-system is based on the principles of adsorptive and desorptive processes between liquid and solid phases. The assay is run fully automated and selective. Procedural losses throughout the analysis are negligible, thereby allowing for external calibration. The calibration curve is linear up to 10 mg/l and concentrations as low as 10 micrograms/l are detectable. CV is 2.5% for within- and 7.5% for between-assay precision at a level of 50 micrograms/l and 1.2% for within- and 8.5% for between-assay precision at a level of 500 micrograms/l. Specific and expensive reagents are not necessary and time-consuming manual operations are not involved. This assay can be selected from a wide spectrum of methods at any time. Thus, the present method is well-suited for drug monitoring purposes in the routine laboratory. In a pharmacokinetic study we measured serum levels of glycyrrhetinic acid in ten healthy young volunteers after ingestion of 500 mg glycyrrhetinic acid. Maximum levels of glycyrrhetinic acid were 6.3 mg/l 2 to 4 hours after ingestion. Twenty-four (24) hours after ingestion seven probands still had glycyrrhetinic acid levels above the detection limit with a mean level of 0.33 mg/l.

  14. 对氯水杨酸的纯度测定%Purity determination of salicylic acid chloride

    Institute of Scientific and Technical Information of China (English)

    杨丰科; 黄震

    2014-01-01

    采用双波长法对对氯水杨酸的纯度进行了测定。对氯水杨酸在乙醇中的最大吸收波长为243 nm,副产物等吸收总波长为267 nm。测定纯对氯水杨酸的标准纯度都超过99.5%,测定市售3种对氯水杨酸的纯度在97.8%~98.0%。研究表明,该方法操作简单,分析数据准确可靠。%Use dual-wavelength method to determine the purity of p-chlorine salicylic acid. The maximum absorption wavelength of p-chlorine salicylic acid in ethanol is 243 nm. The total absorption wavelength of byproducts is 267 nm. Determination of the standard purity of pure p-chlorine salicylic acid more than 99 . 5%. Determination of the purity of three kinds of commercially available p-chlorine salicylic acid was 97. 8 % ~98. 0 %. Studies show that the method is simple,the analytical data is accurate and reliable.

  15. Determination of Uranyl Nitrate and Nitric Acid Based on Density and Conductivity Measurements

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Measurement of the uranium and acidity plays an important role in process control of spent fuel reprocessing. The main chemical compositions including a mount of U solution in spent fuel reprocessing

  16. Determination of effect factor for effective parameter on saccharification of lignocellulosic material by concentrated acid

    Science.gov (United States)

    Aghili, Sina; Nodeh, Ali Arasteh

    2015-12-01

    Tamarisk usage as a new group of lignocelluloses material to produce fermentable sugars in bio ethanol process was studied. The overall aim of this work was to establish the optimum condition for acid hydrolysis of this new material and a mathematical model predicting glucose release as a function of operation variable. Sulfuric acid concentration in the range of 20 to 60%(w/w), process temperature between 60 to 95oC, hydrolysis time from 120 to 240 min and solid content 5,10,15%(w/w) were used as hydrolysis conditions. HPLC was used to analysis of the product. This analysis indicated that glucose was the main fermentable sugar and was increase with time, temperature and solid content and acid concentration was a parabola influence in glucose production. The process was modeled by a quadratic equation. Curve study and model were found that 42% acid concentration, 15 % solid content and 90oC were optimum condition.

  17. Rapid and sensitive determination of acetylsalicylic acid and salicylic acid in plasma using liquid chromatography-tandem mass spectrometry: application to pharmacokinetic study.

    Science.gov (United States)

    Xu, Xiangrong; Koetzner, Lee; Boulet, Jamie; Maselli, Harry; Beyenhof, Jessica; Grover, Gary

    2009-09-01

    A simple and sensitive analytical method using liquid chromatography-tandem mass spectrometry (LC/MS/MS) for determination of acetylsalicylic acid (aspirin, ASA) and its major metabolite, salicylic acid (SA), in animal plasma has been developed and validated. Both ASA and SA in plasma samples containing potassium fluoride were extracted using acetonitrile (protein precipitation) with 0.1% formic acid in it. 6-Methoxysalicylic acid was used as the internal standard (IS). The compounds were separated on a reversed-phase column. The multiple reaction monitoring mode was used with ion transitions of m/z 178.9 --> 136.8, 137.0 --> 93.0 and 167.0 --> 123.0 for ASA, SA and IS, respectively. The lower limits of quantification for ASA and SA were 3 and 30 ng/mL, respectively. The developed method was successfully applied for the evaluation of pharmacokinetics of ASA and SA after p.o. and i.v. administration of 1 mg/kg to rats.

  18. Simultaneous Determination of Gallic Acid, Ellagic Acid, and Eugenol in Syzygium aromaticum and Verification of Chemical Antagonistic Effect by the Combination with Curcuma aromatica Using Regression Analysis.

    Science.gov (United States)

    Kim, Jung-Hoon; Seo, Chang-Seob; Kim, Seong-Sil; Ha, Hyekyung

    2013-01-01

    This study was designed to perform simultaneous determination of three reference compounds in Syzygium aromaticum (SA), gallic acid, ellagic acid, and eugenol, and to investigate the chemical antagonistic effect when combining Curcuma aromatica (CA) with SA, based on chromatographic analysis. The values of LODs and LOQs were 0.01-0.11  μ g/mL and 0.03-0.36  μ g/mL, respectively. The intraday and interday precisions were values, and the recovery was in the range of 92.19-103.24%, with RSD values reference and relative peaks in SA and SA combined with CA (SAC), the amounts of gallic acid and eugenol were increased, while that of ellagic acid was decreased in SAC (compared with SA), and most of peak areas in SA were reduced in SAC. Regression analysis of the relative peak areas between SA and SAC showed r (2) values >0.87, indicating a linear relationship between SA and SAC. These results demonstrate that the components contained in CA could affect the extraction of components of SA mainly in a decreasing manner. The antagonistic effect of CA on SA was verified by chemical analysis.

  19. Identification of novel genetic determinants of erythrocyte membrane fatty acid composition among Greenlanders

    DEFF Research Database (Denmark)

    Andersen, Mette Korre; Jørsboe, Emil; Sandholt, Camilla Helene;

    2016-01-01

    -28) and docosahexaenoic acid (rs6035106 in DTD1, 0.137% (0.025), p = 6.4x10-8), respectively. For a missense variant (rs80356779) in CPT1A, we identified a number of novel FA associations, the strongest with 11-eicosenoic acid (0.473% (0.035), p = 2.6x10-38), and for variants in FADS2 (rs174570), LPCAT3 (rs2110073...

  20. EXTRACTION-CHROMATOGRAPHIC DETERMINATION OF GLUCOSE AND FRUCTOSE IN THE PRESENCE OF AROMATIC AMINO ACIDS

    Directory of Open Access Journals (Sweden)

    Y. I. Korenman

    2012-01-01

    Full Text Available The extraction of glucose and fructose from aqueous salt solutions containing aromatic amino acids (phenylalanine, tryptophan, tyrosine, hydrophilic solvents (aliphatic alcohols, alkyl acetates, ketones have been studied. The quantitative characteric of the process (the distribution coefficients, the degree of extraction, separation factors are calculeted. The dependence of distribution ratios of monosaccharides from the amino acid content in the solution has been established. A mobile phase for analysis of the concentrate by ascending thin layer chromatography have been developed.