SIMPLE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC METHOD FOR THE DETECTION OF PHENYLPROPIONYLGLYCINE IN URINE AS A DIAGNOSTIC-TOOL IN INHERITED MEDIUM-CHAIN ACYL-COENZYME-A DEHYDROGENASE-DEFICIENCY

Deficiency of medium-chain acyl-CoA dehydrogenase is a frequent and tr eatable metabolic defect, which can be diagnosed by detection of pheny lpropionylglycine in urine after an oral load of phenylpropionic acid. We studied the determination of phenylpropionylglycine in urine by is ocratic ion-exclusion chromatography on a cation-exchange column using water-sulphuric acid (pH values between 2 and 4) as mobile phase. Phe nylpropionylglycine, phenylpropionic acid and hippuric acid exhibited high retention factors with only a slight decline at increasing solven t pH. This resulted in a good separation from interfering substances a fter direct injection of urine. We hypothesize that pi-pi interactions between the aromatic carbonic acids and the ion-exchange resin are re sponsible for the strong retention on the stationary phase. We conclud e that, even in asymptomatic patients, determination of phenylpropiony lglycine in urine after a phenylpropionic acid load by ion-exclusion c hromatography is a rapid and reliable diagnostic tool for the detectio n of medium-chain acyl-CoA dehydrogenase deficiency.