APPLICATION OF ION-PAIR HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY TO DETECTION OF THE ATYPICAL COPROPORPHYRIN ISOMER-II AND ISOMER-IV IN HUMAN FECES

A highly selective and sensitive method has been developed for the detection of small amounts of the atypical isomers II and IV of coproporphyrin in human faeces. This method combines liquid-liquid extraction and solid-phase sampling techniques using talc and C18-modified silica gel as the sorbents. Simultaneous separation of the four coproporphyrin isomers I-IV was achieved by isocratic ion-pair high-performance liquid chromatography. Stool samples of healthy subjects (n = 12) contained 1.1 +/- 0.4% (mean +/- S.D.) isomer II and 2.2 +/- 0.9% isomer IV of total coproporphyrins. A somewhat higher content of isomer II (2.7%) and isomer IV (5.4%) was found in faeces of a patient suffering from porphyria variegata.