Ethyl chloroformate as derivatizing reagent for gas chromatographic determination of α-keto acids and amino acids from pharmaceutical preparation

Α-keto acids pyruvic acid (pyr),2-ketobutyric acid (kba),3-methyl-2-oxobutyric acid (mkba),3-methyl-2-oxovalaric acid m3kva),4-methyl-2-oxovalaric acid (m4kva),2- ketohexanoic acid (kha) and phenylpyruvic acid (ppyr) together with amino acids as derivatives of ethyl chloroformate (ecf) eluted and separated from gc column hp-5(30m × 0.32 mm id). the detection was by flame ionization ( (fid). linear calibration curves were obtained within 18-127.8 μg/ml and detection limits were within 6-8.6 μg/ml of each α-keto acid. the separation was repeatable with inter and intraday variation with relative standard deviation (rsd) within 0.2-3.5%. a pharmaceutical preparation ketosteril was analyzed and amounts of mkba,m3kva,m4kva,and ppyr correlated with labeled values and their amount extracted from pharmaceutical preparation by standard addition were calculated to 93.92-96.1 % with rsd 0.3-0.7%. the amino acids present in ketosteril tablet separated completely and were determined simultaneously together with α-keto acids with recovery of 95.8 to 98.65% with rsd 0.2-0.9%.