Abstract

Soulsby, Joan and Smith, R. L. (1974).British Journal of Industrial Medicine,31, 72-74. A simplified method of estimating urinary coproporphyrin is described, based on the method of Rimington (1971). Coproporphyrin and coproporphyrinogen are extracted into ether from acidified urine; the ether is then shaken with a solution of iodine in hydrochloric acid to oxidize any coproporphyrinogen to coproporphyrin and to extract the coproporphyrin. The solution is examined spectrophotometrically for coproporphyrin at the peak of the Soret band and at wavelengths on either side to correct for any impurities present.

A comparison with the method of Rimington (1971) in 94 urine samples with coproporphyrin levels up to 2·5 mg/l showed good agreement. Correlation coefficient (r) = +0·986. One hundred estimations can be carried out in five hours.