Determination of porphyrins in urine by direct injection on a liquid chromatographic column coated with tributylphosphate.

To separate and quantify urinary porphyrins, acidified and centrifuged urine was injected on a reversed-phase high-performance liquid chromatographic column, LiChrosorb RP-18, coated with tributylphosphate. A linear pH gradient from pH 4.40 to pH 6.50 was applied in the eluent using phosphate buffers containing methanol (9:1). The method permits detection of uro- and coproporphyrin down to concentrations normally present in urine and also selective determination of the hepta-, hexa- and pentacarboxylic porphyrins present in urine from patients suffering from porphyria cutanea tarda.