ISOTOPE-DILUTION MASS-SPECTROMETRY AS A CANDIDATE DEFINITIVE METHOD FOR DETERMINING TOTAL GLYCERIDES AND TRIGLYCERIDES IN SERUM

A new isotope dilution mass spectrometric method for total glycerides and triglycerides in human serum is described. Total glycerides are de fined as the sum of tri-, di-, and monoglycerides plus free glycerol; triglycerides are defined as the pure triglyceride species. In both de terminations, serum samples are supplemented by addition of [C-13(3)]t ripalmitin, processed, derivatized, and the abundance ratios of select ed ions are determined. Bias is investigated by quantifying the analyt e in the same samples under different chromatographic and ionization c onditions. The analytes were determined in two human serum pools. The CV for a single measurement ranged from 0.35% to 0.72%, and the relati ve SEM ranged from 0.10% to 0.34%; there was no significant bias in th e measurements. The combination of high precision and absence of signi ficant bias in the results qualify this method for consideration as a Definitive Method as defined by the National Committee for Clinical La boratory Standards.