Screening for Disorders of Purine and Pyrimidine Metabolism Using HPLC-Electrospray Tandem Mass Spectrometry

Abstract

The concentrations of purine and pyrimidine metabolites in urine are useful indicators for the diagnosis of patients suspected of an inborn error of the purine and pyrimidine pathway or a urea-cycle defect. In this paper, we describe a fast and specific method to measure these metabolites in liquid urine samples or urine-soaked filter paper strips. The filter paper strips offer the advantage of easy collection, transport, and storage of the urine samples. Analysis of 23 purine and pyrimidine metabolites is performed using reverse-phase HPLC combined with electrospray ionization (ESI) tandem mass spectrometry (MS/MS). Detection is performed by multiple reaction monitoring and transitions and instrument settings are established for all metabolites. Stable-isotope-labeled reference compounds are used as internal standards. With a total analysis time of 15 min, HPLC-ESI MS/MS proves to be a rapid screening method for disorders of purine and pyrimidine metabolism.