ANALYSIS OF CONJUGATED BILE-ACIDS BY ONLINE SUPERCRITICAL FLUID CHROMATOGRAPHY THERMOSPRAY MASS-SPECTROMETRY

A rapid method was developed for the analysis of polar conjugated bile acids by combined packed column supercritical fluid chromatography/mass spectrometry. Direct coupling of the column to the mass spectrometer was effected with a modified thermospray interface operated in the filament-on mode. Maximum sensitivity for the bile acid conjugates was achieved by recording the negative ions generated in the ionization process. The effects of vaporizer and source temperatures, repeller voltage and discharge conditions on the bile acid response were investigated. The mass spectra obtained for the common glycine and taurine conjugates yielded only the [M - H]- pseudo-molecular ions. In contrast with the taurine derivatives, the glycine forms produced a weak ion current and exhibited broad bands. The applicability of the technique is illustrated with a sample of human bile.