27 research outputs found
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High-performance liquid chromatography of selenium compounds utilizing perfluorinated carboxylic acid ion-pairing agents and inductively coupled plasma and electrospray ionization mass spectrometric detection
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Identification of the principal selenium compounds in selenium-enriched natural sample extracts by ion-pair liquid chromatography with inductively coupled plasma- and electrospray ionization-mass spectrometric detection
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Characterization of selenium species in biological extracts by enhanced ion-pair liquid chromatography with inductively coupled plasma-mass spectrometry and by referenced electrospray ionization-mass spectrometry
Selenium is an essential nutrient for humans; selenium compounds catalyze intermediate metabolism reactionsand inhibit the toxic effects of heavy metals such as arsenic, cadmium and mercury. Some extracts of seleniumenrichedbiological materials show cancer preventive effects, tentatively attributable to the biological functions ofselenoamino acids. An improved ion pair chromatographic method with methodological enhancements for theseparation, qualitative and quantitative determination of non-volatile selenium compounds extracted from differentsamples has been developed using ICP-MS as an element-selective detector. Separation power early in thechromatogram was increased to baseline separation in the standard mixture as a result of decreasing spray chambersize from 97 to 14 ml, and increasing trifluoracetic acid TFA. concentration in the mobile phase from 0.1 to 0.6%.The former pH was restored by the addition of ammonia to the mobile phase, which also served to increase thecolumn recovery of inorganic anions. Calibration curves for different selenoamino acids showed statistically differentbehavior. Biological sample extracts were characterized using HPLC-ICP-MS. Mass spectral behavior of selenoamino acids,using electrospray and ion trap technology with direct infusion and liquid chromatographic sample introduc-tion, is alsoreported
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Anticarcinogenic organoselenium compounds - Chromatographic, atomic and molecular mass spectral speciation
There is substantial evidence of the complexity of selenium speciation in living organismsand of the importance of the selective determination of the particular species of this elementin order to understand its metabolism and biological significance in clinical chemistry, biology,toxicology, and nutrition. The state-of-the-art of analytical techniques available for thispurpose is critically evaluated with particular emphasis on the element-selective detectionand identification of the detected selenium compounds. Whereas there are a number of techniquesavailable, which can detect various selenium species in living organisms selectively,few techniques exist that are able to identify and to characterize the species detected
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Analytical selenoamino acid studies by chromatography with interfaced atomic mass spectrometry and atomic emission spectral detection
Consumption of selenium enriched plants oryeast-based nutritional supplements has been reported toprovide anticarcinogenic benefits which are seleniumcompound dependent. Separation and identification ofthese selenium compounds is critical to understand the activity.Plants and yeast convert inorganic selenium in thesoil or growth media into organoselenium compounds,probably following a route similar to the sulfur assimilatorypathway. Non-volatile selenium compounds producedinclude selenoamino acids, some of which haveshown anticarcinogenic activity. Volatile compounds producedby chemical reaction of involatile precursors havealso been found. An ion pair chromatographic methodwith ICP-MS detection for the separation of selenoaminoacid standards potentially present in real samples is given.The method allows separation of selenoamino acids includingsuch analytes as the cis-trans isomers of Se-1-propenyl-DL-selenocysteine. The method also providesthe capability of determining the presence of selenoxidesand possibly selenones, and tracking of other functionalitiesand reactions by selective derivatization. Alternatively,selenoamino acids are treated with ethylchloroformateto produce stable volatile derivatives which areamenable to GC separation with element specific atomicemission detection (GC-AED). Results of total seleniumdetermination and speciation of selenium enriched yeastbasednutritional supplements, selenium enriched alliumvegetables and bioremediation samples are presented
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Chemical speciation influences comparative activity of selenium-enriched garlic and yeast in mammary cancer prevention
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Determination of selenoamino acids and other non-volatile organoselenium compounds in natural samples by HPLC-ICP-MS.
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