The use of mass fragmentography in the evaluation of routine methods for glucose determination

A highly specific and accurate mass fragmentographic reference method for determination of serum glucose is described. A fixed amount of hepta-deuterated glucose is added to a fixed amount of serum. The mixture is lyophilized, converted into the penta-trimethylsilyl-methyloxime derivative and subjected to analysis with a combined gas chromatograph - mass spectrometer equipped with a MID-unit (multiple ion detector). The amount of unlabeled glucose was determined from the ratio between recordings at m/e 319 and 323. The two ions used correspond to the base peak in the mass spectrum of derivative of unlabeled and hepta-deuterium labeled glucose, respectively. The relative standard deviation of the method was 1.9%. The method was compared with different enzymatic methods based on the hexokinase reaction and the glucose oxidase reaction. Of the different methods tested, a glucose oxidase method with determination of maximal rate of consumption of oxygen gave results most close to the results of the reference method.