Analysis of free stool porphyrins by high-performance liquid chromatography.

The determination of stool porphyrins is necessary for the diagnosis of some porphyrias in clinical laboratories. Quantitative methods for the analysis of faeces for porphyrins are unpleasant and difficult to perform. An extraction and ion-pair reversed-phase high-performance liquid chromatographic procedure is described for the separation and determination of individual free stool porphyrins. The within-assay coefficients of variation range from 2 to 6%. A linear response curve is observed between 38 and 380 nmol/g for coproporphyrin I in dry stool The method can be applied to the routine analysis of free stool porphyrins in the clinical laboratory.