High-performance liquid chromatographic determination of glyoxylic acid in urine.

A high-performance liquid chromatographic (HPLC) method for the determination of urinary glyoxylic acid is proposed. The system is based on the precolumn derivatization of alpha-keto acids by means of phenylhydrazine, separation of the phenylhydrazone formed by HPLC and spectrophotometric detection at 324 nm. The method is precise and allows the determination of 0.5 mumol/l glyoxylate. The poor stability of glyoxylate under all conventional preservation conditions requires the analysis to be carried out as soon as possible after urine collection. Results of determinations on urine samples from healthy controls and from patients with idiopathic calcium stone disease and type I primary hyperoxaluria are reported.