title: Branched-chain alpha-keto acid analysis in biological fluids: preparative clean-up by anion-exchange and analysis by capillary gas chromatography.
abstract: A method is given for the quantitative analysis of the alpha-keto derivatives of the branched-chain amino acids in physiological fluids. A sample containing alpha-ketovalerate and alpha-ketocaproate as internal standards is passed through a weak anion-exchange resin at neutral pH. After washing the resin with distilled water, the alpha-keto acids are eluted with 4 M hydrochloric acid--ethanol (50:50). Quinoxalinol derivatives are prepared directly in the eluent, extracted with methylene chloride, and trimethylsilylated. Separation of the derivatives is by capillary gas chromatography on a 30 m fused-silica SE-30 column. Chromatographic separation is superior to that reported for packed column methods, thereby permitting the use of alpha-ketovalerate and alpha-ketocaproate as internal standards.
mesh_terms: D000818:Animals; D001826:Body Fluids / Q000032:analysis*; D002417:Cattle; D002849:Chromatography, Gas; D002852:Chromatography, Ion Exchange; D006801:Humans; D007475:Ion Exchange Resins; D007651:Keto Acids / Q000032:analysis* / Q000097:blood; D009132:Muscles / Q000378:metabolism; D051381:Rats; D013045:Species Specificity
chemical_list: D007475:Ion Exchange Resins; D007651:Keto Acids