Doss: Thin-layer chromatography of porphyrin methyl esters

Thin-layer chromatography methods on the preparative and analytical scale are presented for the separation of porphyrin methyl esters according to the number of ester groups in each porphyrin. Complete and sharp separations are obtained on silica gel glass plates or aluminium cards run in benzene-ethyl acetate-methanol solvent systems. Dicarboxylic porphyrin esters from proto-, deuteroand hematoporphyrin IX have also been separated. Modifications of the analytical methods are described for the rapid separation of porphyrins bearing eight to two methyl ester groups within 10 min on small chromatocards in chloroform-ethyl acetate solvent mixtures. The porphyrins are determined quantitatively by spectrophotometric analysis of the eluted substances, or by fluorescence scanning of the bands of thin-layer chromatograms, using the Camag-Turner TLC-scanner. The fluorometric method is highly sensitive and permits a simultaneous relative measurement of all bands in the chromatogram. Examples of thin-layer chromatograms in combination with fluorescence scanning are presented, demonstrating the application of this new analytical method.