SEPARATION OF TYPE-I AND III ISOMERS OF COPROPORPHYRIN AND UROPORPHYRIN USING AFFINITY CAPILLARY ELECTROPHORESIS

Naturally occurring 8- and 4-carboxylic porphyrin I and III isomers ar e separated using a run buffer consisting of bovine serum albumin (BSA ) and phosphate as the electrolyte. The method requires the use of dea ctivated capillaries to minimize protein-wall interactions. The uropor phyrin isomers are resolved in 15 minutes while the separation of the coproporphyrin isomers requires 28 minutes. Retention times are largel y characteristic of the number of carboxylic acid side chains as well as the relative affinity for BSA. The binding of porphyrins to BSA is supported by a wavelength maxima red shift in the soret region when us ing BSA in the run buffer.