Direct coupling of micro high-performance liquid chromatography with fast atom bombardment mass spectrometry. II. Application to gradient elution of bile acids.

A new system without a moving belt has been developed for direct coupling of micro high-performance liquid chromatography with fast atom (xenon or argon) bombardment mass spectrometry. The structure of the interface was basically the same as used previously, but the mass spectrometer was modified by adding both a liquid nitrogen trap between the ion source housing and the diffusion pump, and a position adjuster for the interface. Stable ionization of the solute in a glycerol matrix is achieved at flow-rates below 2 microliter/min. The system was applied to the analysis of bile acids by gradient elution chromatography. Steady baselines were observed in the mass chromatograms.