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 defined as the sum of tri-, di-, and monoglycerides plus free glycerol; triglycerides are defined as the pure triglyceride species. In both determinations, serum samples are supplemented by addition of [13C3]tripalmitin, processed, derivatized, and the abundance ratios of selected ions are determined. Bias is investigated by quantifying the analyte in the same samples under different chromatographic and ionization conditions. The analytes were determined in two human serum pools. The CV for a single measurement ranged from 0.35% to 0.72%, and the relative SEM ranged from 0.10% to 0.34%; there was no significant bias in the measurements. The combination of high precision and absence of significant bias in the results qualify this method for consideration as a Definitive Method as defined by the National Committee for Clinical Laboratory Standards.