A method is described for the rapid determination of urinary
bile salt profiles by fast atom bombardment--mass spectrometry (FAB-MS). Urine was passed through a reverse-phase
octadecylsilane bonded
silica cartridge and the
bile salts eluted with
methanol. Negative ion FAB spectra could be obtained from the equivalent of 10 microliter of urine loaded onto the target probe with
glycerol as matrix. In samples from normal infants and children
bile salt peaks were rarely detectable above the background whereas peaks produced by
steroid sulphates and
glucuronides and
bile alcohol glucuronides could usually be identified. In samples from infants and children with
cholestasis the major peaks were produced by the
taurine and
glycine conjugates of di-, tri- and tetrahydroxycholanoic
acids (and their monosulphates). In samples from patients with
Zellweger syndrome and
infantile Refsum's disease, a unique ion at m/z 572 indicated the presence of
taurine-conjugated tetrahydroxy-cholestanoic
acid(s). The
amide linkage to
taurine was cleaved by alkaline hydrolysis but not by
cholylglycine hydrolase. Capillary gas chromatography--mass spectrometry (GC-MS) of the
bile acids liberated by alkaline hydrolysis indicated the presence of at least two nuclear-tetrahydroxylated cholestanoic
acids, probably the 6 alpha- and 1 beta-hydroxylated derivatives of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestan-26-oic
acid.