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

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.