USE OF [6,6-H-2(2)]GLUCOSE AND OF LOW-ENRICHMENT [U-C-13(6)]-GLUCOSE FOR SEQUENTIAL OR SIMULTANEOUS MEASUREMENTS OF GLUCOSE-TURNOVER BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

We developed gas chromatography-mass spectrometric methods for assayin g the enrichment of 99 at.% [6,6-H-2(2)]glucose and 30 at.% [U-C-6(13) glucose, although both tracers are mostly M + 2. C-13 enrichment is de termined either by the C-1 to C-5 fragment of glucose aldonitrile pent aacetate or by oxidation of glucose to glucarate. H-2 enrichment is as sayed as the difference between the C-13 enrichment of glucarate and t he H-2 + C-13 enrichment of glucose. The techniques, which were valida ted in in vivo experiments, are applicable to the determination of sim ultaneous or sequential measurements of the rate of glucose appearance before and after an intervention. They could also be applied to the s imultaneous determination of (i) gluconeogenesis by incorporation of a C-13-labeled precursor into glucose and (ii) the rate of glucose appe arance by [6,6-H-2(2)]glucose infusion. (C) 1994 Academic Press, Inc.