Determination of hematoporphyrin and protoporphyrin by ion-pair extraction with chlorpromazine.

A sensitive method based on ion-pair extraction is described for the quantification of hematoporphyrin and protoporphyrin using chlorpromazine as an ion-pair-forming agent. Extraction of the ion-pair in chloroform is obtained quickly at an optimum pH of 6.5 for hematoporphyrin and 6.5-6.8 for protoporphyrin, giving an excellent recovery of the porphyrin. A stoichiometric relationship of 1:2 between porphyrin and chlorpromazine is proved. Cyanocobalamin and liver extract do not interfere with the assay.