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21st International Symposium on Chromatography

作者： Rastogi, SC Barwick, VJ Carter, SV LAB GOVT CHEMIST TEDDINGTON TW11 0LY MIDDX ENGLAND

A method for the analysis of organic cosmetic colourants was developed. The colourants extracted from the cosmetic products were analysed by HPLC followed by diode-array detection across the wavelength range 275 nm-760 nm. The chromatographic separation was performed on a column with a polymeric packing using gradient elution with a mobile phase composed of citrate buffer, the ion-pairing reagent tetrabutylammonium hydroxide, acetonitrile and tetrahydrofuran. The colourants were identified on the basis of their retention times as well as their UV-visible spectra. A spectral library consisting of retention times and UV-visible spectra of 130 organic cosmetic colourants has been built for the purpose of identifying of colouring matter in cosmetic products. Solid-phase extraction methods using;C-18 silica and aminobonded silica have been developed for the extraction of colourants from various types of cosmetic products. The method for the identification of colourants in nail varnishes and lipsticks has been optimized for routine analysis.

关键词： column liquid chromatography solid phase extraction diode array detection UV-visible spectral library cosmetics colourants

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HPLC determination of carminic acid in foodstuffs and beverages using diode array and fluorescence detection

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CHROMATOGRAPHIA 1997年第1期45卷 63-66页

作者： Carvalho, PRN Collins, CH UNIV ESTADUAL CAMPINAS INST QUIMBR-13083970 CAMPINASSPBRAZIL INST TECNOL ALIMENTOS BR-13073001 CAMPINASBRAZIL

Carmine extracted from cochineal insects is one of the most used natural colorings for beverages and other foods. Its active ingredient is carminic acid (7-beta-D-glucopyranosyl-9,10-dihydro-3,5,6,8-tetrahydroxy-1-methyl-9,10-dioxo-2-anthracenecarboxylic acid). This work describes a rapid HPLC determination of carminic acid and compares diode array and fluorescence detection for quantification. Samples with higher protein levels, such as milk and yogurt, are first treated with 1 mt of 8 M NH4OH (5 min), the pH is reduced to 2 with 6 M HCl before centrifugation, the supernatant is then filtered and injected into the chromatograph. Low protein samples are simply filtered before injection. The separations were performed with a LiChroCART RP18 column using a mixture of acetonitrile and formic acid as mobile phase. The optimized conditions permit baseline quantification of the carminic acid even in the presence of other coloring agents. The sampling and analytical procedures are considerably faster than those of the literature and present excellent recuperation, selectivity, accuracy and precision. The method was applied to analysis of several yogurts and beverages.

关键词： column liquid chromatography diode array detection fluorescence detection carminic acid

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HPLC determination of carminic acid in foodstuffs and beverages using diode array and fluorescence detection

HPLC determination of carminic acid in foodstuffs and bevera...

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21st International Symposium on Chromatography

作者： Carvalho, PRN Collins, CH UNIV ESTADUAL CAMPINAS INST QUIMBR-13083970 CAMPINASSPBRAZIL INST TECNOL ALIMENTOS BR-13073001 CAMPINASBRAZIL

关键词： column liquid chromatography diode array detection fluorescence detection carminic acid

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Isoflavone levels in soy foods consumed by multiethnic populations in Singapore and Hawaii

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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 1999年第3期47卷 977-986页

作者： Franke, AA Hankin, JH Yu, MC Maskarinec, G Low, SH Custer, LJ Canc Res Ctr Hawaii Honolulu HI 96813 USA Univ So Calif Norris Comprehens Canc Ctr Los Angeles CA 90033 USA Natl Univ Singapore Dept Community Occupat & Family Med Singapore 119074 Singapore

Concentrations and glucosidic conjugation patterns of isoflavones were determined in soy foods consumed by multiethnic populations in Singapore and Hawaii. Six raw and 11 cooked food groups traditionally consumed in Singapore and 8 food groups consumed in Hawaii were analyzed by reversed-phase high-pressure liquid chromatography with diode array detection. Mean total isoflavone levels varied between 35 and 7500 ppm, with the lowest values found in soy milk and burgers and the highest levels observed in soybean and its seeds and in supplements. Total isoflavone levels and conjugation patterns varied as a function of soybean variety, storage conditions, and food processing. A large contribution to the differences in total isoflavone content between food groups was due to the water content in foods and to leaching of polar analytes into the water phase during boiling. Soy protein drinks and traditional soy foods were found to possess very similar isoflavone amounts considering usual serving sizes.

关键词： isoflavones genistein daidzein glycitein isoflavone conjugates soy foods supplements high-pressure liquid chromatography diode array detection

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Analysis of polyphenols using capillary zone electrophoresis and HPLC: detection of soy, lupin, and pea protein in meat products

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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 1999年第2期47卷 594-602页

作者： Mellenthin, O Galensa, R Univ Bonn Inst Lebensmittelwissensch & Lebensmittelchem D-53115 Bonn Germany

The analysis of polyphenols, which are characteristic of certain legumes, enables a rapid and sensitive detection of legume proteins in meat products. Separation of specific isoflavones can be achieved by capillary zone electrophoresis (CZE) or high-performance liquid chromatography (HPLC), both coupled with a photodiode array detector (DAD). The use of CZE in the identification process is an appropriate means of rapid screening;the HPLC is less dependent on matrix effects and clearly more sensitive. Additives of soy protein isolates up to 0.1% could be detected in meat products, even in sausages heated to a high temperature or with hydrolyzed soy proteins. A solid-phase extraction procedure with polyamide cartridges has been developed to concentrate polyphenols. A similar detection of lupin protein is possible in principle. In the case of pea protein, a reliable detection was not possible depending on the coincidental appearance of polyphenols as indicating substances.

关键词： polyphenols isoflavones genistein legume protein soy lupin pea meat products capillary electrophoresis CZE HPLC diode array detection solid-phase extraction

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detection of Maillard products of lactose in heated or processed milk by HPLC/DAD

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ZEITSCHRIFT FUR LEBENSMITTEL-UNTERSUCHUNG UND-FORSCHUNG A-FOOD RESEARCH AND TECHNOLOGY 1999年第3期208卷 172-177页

作者： Pischetsrieder, M Gross, U Schoetter, C Univ Munich Inst Pharm Abt Lebensmittelchem D-80333 Munich Germany

Two HPLC methods with diode array detection were used to separate Maillard products from milk components. The Maillard products 4-(beta-D-galactopyranosyloxy)-2-hydroxy-2-methyl-2H-pyran-3(6H)-one (2), 1-[3-(beta-D-galactopyranosyloxy)-2-furanyl]-1-ethanone (3), 4-(beta-D-galactopyranosyloxy)-5-(hydroxymethyl)-2-methyl-3(2H)-furanone (5), isomaltol (7),maltol (9), 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (6), and 5-hydroxymethyl-2-furfuraldehyde (8) were determined using a water-methanol gradient. Furthermore, 4,5-dihydroxy-2-(beta-D-galactopyranosyloxy)- 5-methyl-7-cyclopenten-1-one (3) was separated from the milk components by applying the interaction reagent octylamine. Several heated or processed milk samples were analyzed, and formation of the Maillard products was determined and quantified. Thus it was found that 2 and 3 are early products of the Maillard reaction in milli, whereas after prolonged heating 4, 5, and particularly 9 and 6 become more important. Compounds 7 and 8 were not detected, even if the samples were heated under stringent conditions.

关键词： Maillard reaction milk high performance liquid chromatography diode array detection

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Determination of nitrophenols, nitrobenzoic acids and polar explosives by HPLC-diode array detection in ground water samples of former ammunition plants

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CHROMATOGRAPHIA 1996年第11-12期43卷 612-618页

作者： Godejohann, M Preiss, A Levsen, K Wunsch, G FRAUNHOFER INST TOXICOL & AEROSOLFORSCH D-30625 HANNOVERGERMANY UNIV HANNOVER LEHRGEBIET ANALYT CHEMINST ANORGAN CHEMD-30167 HANNOVERGERMANY

An HPLC method with diode array detection for the determination of acidic aromatic nitro compounds (in particular nitrophenols and nitrobenzoic acids) in ground water around former ammunition plants is presented. The use of an isocratic mobile phase, buffered to a pH of 2.30 on a reversed phase column, allows the separation of several nitrophenols and nitrobenzoic acids, some of which are known as phototransformation products of 2,4,6-trinitrotoluene (TNT). In a ground water sample from the former ammunition site at Elsnig (Saxony, Germany) 2,4- and 3,5-dinitrophenol (18), picric acid (8) and 2,4-dinitrobenzoic acid (3) were identified in addition to a variety of explosives determined previously. The presence of these compounds was corroborated by a diode-array (DAD)-library search.

关键词： column liquid chromatography diode array detection explosives residues nitro-compounds ground water ammunition waste

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Cell wall esterified phenolic dimers: Identification and quantification by reverse phase high performance liquid chromatography and diode array detection

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PHYTOCHEMICAL ANALYSIS 1996年第6期7卷 305-312页

作者： Waldron, KW Parr, AJ Ng, A Ralph, J USDA ARS US DAIRY FORAGE RES CTR MADISON WI 53706 USA

An optimized high performance liquid chromatography (HPLC) procedure has been developed for the analysis and quantification of all of the known ferulic acid dehydrodimers, and the principle phenolic aldehydes and acids, found in the cell walls of higher plants. The HPLC system uses an ODS2 reverse phase column (5 mu m particle size) eluted with a methanol, acetonitrile and water gradient with detection at 280 nm. In addition to providing baseline resolution of most components, the method employs a spectrometric detector which enables the precise identification of eluted components through the analysis of their spectral properties, Analysis of the cell wall phenolics of wheat straw stem (Triticum vulgare) was carried out using this method which is highly versatile and, for certain components, more sensitive than the current gas chromatography-mass spectrometry methodology.

关键词： high performance liquid chromatography diode array detection cell walls phenolics dehydrodimers ferulic acid

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Application of GPC coupled with diode-array detector for the study of oxidative changes in styrene-butadiene copolymers

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INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND CHARACTERIZATION 1998年第3期4卷 247-262页

作者： Pulda, J Cihak, P Kaucuk SV Lebedev Synthet Rubber Res Inst Kralupy 27852 Czech Republic Kaucuk SV Lebedev Synthet Rubber Res Inst Vitavou Czech Republic

The combination of GPC with a diode-array detector (DAD) was utilized for the determination of the oxidation course of styrene-butadiene copolymers. This article describes the use of a facile GPC-DAD technique to determine the relative contents of hydroxyl and carbonyl functional groups formed during oxidation along the molecular weight distribution. Hydroxyl and carbonyl groups detection is based on derivatization of these groups resulting in uniquely strongly UV-visible absorbing derivatives. The relative changes in molecular weight distribution were determined simultaneously. The results from the analysis can be valuable information for elucidation of degradation and branching processes during polymer oxidation.

关键词： gel permeation chromatography diode array detection styrene-butadiene copolymer oxidation derivatization

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HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH diode-array detection FOR THE DETERMINATION OF PESTICIDES IN WATER USING AUTOMATED SOLID-PHASE EXTRACTION

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ANALYST 1995年第4期120卷 1133-1136页

作者： NOURI, B FOUILLET, B TOUSSAINT, G CHAMBON, P INST PASTEUR LYON DEPT HYG APPL HOMME & ENVIRONNEMENTF-69365 LYON 07FRANCE

An accurate, economical and sensitive method was developed for the simultaneous determination of phenylureas, phenoxy acids, some nitriles and nitrophenols in aqueous samples. The method is based on automated solid-phase extraction and high-performance liquid chromatography with diode-array detection. The analytes were separated on a 25 cm C-18 analytical column and determined at three wavelengths simultaneously, 220, 240 and 270 nm. The solid-phase extraction time was less than 1 h for sis water samples and the lowest detectable concentrations were in the range 25-100 ng l(-1) The recoveries of the pesticides ranged from 85 to 99% and the relative standard deviations were in the range 1-10% at 200 ng l(-1) (n = 6).

关键词： PESTICIDE DETERMINATION SOLID PHASE EXTRACTION HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY diode array detection WATER ANALYSIS

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