Liquid-chromatographic separation and determination of coproporphyrins I and III in urine

We describe a method of determining coproporphyrin I, III, and I plus III in urine by "high-performance" liquid chromatography. Urine is simply injected after dilution with an equal volume of glacial acetic acid. Some urinary coproporphyrin apparently binds zinc without acetic acid treatment. The working linear range of coproporphyrin concentrations is 10 to 2000 micrograms/L of urine. The sensitivity of the method is sufficient to detect as little as 10 micrograms of coproporphyrins per liter of urine. Analytical recoveries for both coproporphyrins were 96.7-106%. Results by the present method and those by an extraction method (Br J Ind Med 31:72-74, 1974) correlate well (r = 0.975). Mean (and range) coproporphyrin I, III, and I plus III concentrations in urine from normal subjects are 33.7 (7-75), 28.6 (0-130), and 62.2 (7-174) micrograms/L, respectively.