Capillary gas chromatography combined with ion trap detection for quantitative profiling of polyols in cerebrospinal...

Polyol species in cerebrospinal fluid and plasma--ribitol, arabitol, xylitol, 1,5-anhydrosorbitol, myo-inositol, mannitol, sorbitol, and galactitol--simultaneously were quantitated by a capillary gas chromatography/ion trap (mass spectrometric) detection method. The details of the methodology are discussed and the results of analysis of polyols in healthy human subjects are reported. Microliter volumes of cerebrospinal fluid or plasma were mixed with internal standard (deuterium labeled myo-inositol), deproteinized, and evaporated to dryness. Polyols were acetylated in the presence of pyridine catalyst and washed with sodium bicarbonate solution and the acetate derivatives were recovered. Standard curve solutions were similarly treated. The polyol components were resolved on a capillary column bonded with 50% phenyl-50% methyl polysiloxane. Chemical ionization mass spectra for the acetate derivatives of polyols were generated in an ion trap using acetonitrile as reagent gas. Each polyol yielded a fragment ion in 100% abundance arising probably from the loss of one acetate moiety from the protonated molecule. These ions were monitored. The relative standard deviation (within-day) for quantitation of polyols was not greater than 8% for cerebrospinal fluid and 15% for plasma matrix. A polyol profile in cerebrospinal fluid and plasma was determined in healthy human subjects and a cerebrospinal fluid/plasma concentration ratio larger than 1.0 was found for all polyol species except 1,5-anhydrosorbitol and xylitol. This assay technique will be used to study the role of polyols in central nervous system diseases.