MICELLAR ELECTROKINETIC CHROMATOGRAPHY OF BILIRUBIN AND RELATED COMPOUNDS IN UNCONJUGATED AND GLYCO-CONJUGATED BILE SALT SOLUTIONS

Abstract

The interactions of bilirubin, biliverdin, xanthobilirubin, biliverdin dimethyl ester, and xanthobilirubin methyl ester with unconjugated and glyco-conjugated bile salt solutions were investigated by micellar electrokinetic chromatography (MEKC). The capacity factors were measured in solutions of the different bile salts over the pH range of 6.5 to 8.5. The bile salts investigated were deoxycholic, chenodeoxycholic, glycocholic, glycodeoxycholic, and glycochenodeoxycholic acid. These results were compared to previous results in cholic, taurocholic, taurodeoxycholic, and taurochenodeoxycholic acids. Typically, the nature of the bile salt, trihydroxy versus dihydroxy, has a greater effect on the resulting capacity factors than does the nature of the conjugation. The influence on capacity factor of such features as molecular size, shape, and charge are revealed with this group of analytes.

ACKNOWLEDGMENTS

WEK and MMB thank Professor David Lightner of the University of Nevada at Reno for the generous gift of xanthobilirubin methyl ester. VAE and JWQ were supported by NSF-REU Grant No. CHE-9531357. PAS was supported by the Welch Foundation (W-003). MMB is a Henry Dreyfus Teacher-Scholar. The current address for VAE is Department of Chemistry and Biochemistry, Box 21, St. Mary's University, One Camino Santa Maria, San Antonio, TX 78228. The current address for JWQ is Department of Natural Sciences, Del Mar College, Corpus Christi, TX 78404.