Abstract
Urinary α-Ketoglutaric acid was determined by gas chromatography as its trimethylsilylated quinoxalone derivative. Urine was evaporated and the residue reacted with o-phenylenediamine. Ethyl acetate was used to extract the quinoxalone thus formed. The quinoxalone was trimethysilylated and measured with an OV - 17 column. Normal and phenylketonuric urines were analyzed.