Separation of the coprophorphyrin isomers I and III by thin-layer chromatography.

An improved, specific and sensitive method for the determination of the coproporphyrin isomers I and III is described. In this method, the hydrolysis of the coproporphyrin methyl esters takes place in the silica gel layer of acid-resistant pre-coated thin layer plates. After chromatography in the solvent system 2,6-dimethylpyridine/water, (volume ratio 20 ml + 6 ml), in an ammonia atmosphere, the isomers are measured, either directly in the silica gel layer by fluorimetry, or after elution in 1.0 mol/l hydrochloric acid. The technique makes analysis in the nanogram range possible. See article.