High-performance liquid chromatographic assay of argininosuccinate: its application in argininosuccinic aciduria and in normal man.

Argininosuccinate (ASA) is determined in a few minutes with little manipulation by reversed phase high-performance liquid chromatography (HPLC) using O-phthaldialdehyde. The two cyclic anhydrides of ASA are not formed during analysis but, if present, can be determined simultaneously. As little as 1 nl urine from a patient with argininosuccinic aciduria was sufficient for analysis; the ASA/creatinine ratio was 50.8 mmol g-1 and daily excretion was 5-7g ASA. We found small amounts of the two anhydrides in the patient's urine and we give factors to estimate, from their peaks, the corresponding amount of ASA. Urine from normal children showed a small acid-labile (at 100 degrees C) peak at the ASA position, which we tentatively assign to genuine ASA. From this peak less than 2mg ASA day-1 were excreted in our controls. Procedures for collection and storage of samples and the potential of this method for heterozygote detection are discussed.