Determination of serum triglycerides by mass fragmentography

A mass fragmentographic reference method for determination of serum triglycerides is described. A fixed amount of a mixture of [1,1,2,3,3-2H5]glycerol tripalmitate and [1,1,2,3,3-2H5]glycerol trioleate (500 nmol) is added to a fixed amount of serum (250 mul) and extracted with chloroform/methanol (2 : 1, v/v). The triglycerides are isolated by means of thin-layer chromatography. The glycerol obtained after acid hydrolysis is converted into the tri-trimethylsilyl derivative and the amount of unlabeled glycerol is determined from the ratio between the recordings at m/e 218 m/e 222, obtained after analysis with a gas chromatograph-mass spectrometer equipped with an MID (multiple ion detector). The two ions correspond to the peak at M--90 and M--91 in the mass spectrum of the tri-trimethylsilyl derivative of unlabeled and (1,1,2,3,3-2H5)-labeled glycerol. The relative standard deviation of the method in the range 0.4--5.8 mmol/l was 2.4%. A fully enzymatic routine method for determination triglycerides was compared with the mass fragmentographic reference method. There was a good correlation between the two methods (r = 0.995) and the regression coefficient was 1.19.