Evaluation of filter paper collection of urine samples for detection and measurement of organic acidurias by capillary electrophoresis.

There is little doubt that mental retardation has been prevented in most babies diagnosed by newborn screening programs for inborn errors and the cost-benefit ratios of these programs have been reported as highly positive. In a previous work we optimised a CE method for quick profiling of organic acidurias, which characterize a large number of inborn errors, so that it permits the separation, detection and even identification in less than 15 min of 22 organic acids in urine samples related to a wide range of metabolic disorders. In the present work we have studied the adequacy of filter paper collection of urine samples to simplify this step, always difficult in babies, when it is not performed by training personnel. The studied parameters were: media and conditions for re-extraction to give the best sensitivity and a more simple procedure when the samples are measured by CE, interferences coming from the diaper, recoveries obtained, possible correction of recoveries with creatinine and stability of the compounds. The whole method we report has the advantages of easy sample collection, easy shipping or delivery, and rapid analysis. Moreover, this method of collection and analysis allows the identification and quantitation of fumaric, methylmalonic, N-acetylaspartic, pyroglutamic and homogentisic acids, as well as glutaric acid for which screening is considered especially advisable.