Identification and quantification of ethylene glycol and diethylene glycol in plasma using gas chromatography-mass spectrometry.

A method for the gas chromatographic-mass spectrometric identification and quantification of ethylene glycol and diethylene glycol in plasma is described. Such a method is necessary in clinical and forensic toxicology to diagnose probable intoxication and to control the efficacy of detoxification. For sample preparation, the glycols were isolated using acetone after the addition of 1,3-propylene glycol as internal standard. The glycols were then esterified by pivalic acid (pivalic acid anhydride, triethylamine and methanol, 70 degrees C, 15 min) to improve their gas chromatographic characteristics. The glycols were first identified by a comparison of the full mass spectra with reference spectra and then quantified. Therefore, the peak area ratio in the total ion chromatogram (ethylene glycol or diethylene glycol/1,3-propanediol) of the sample was compared with the calibration curve in which the peak area ratios of the standards (0.05, 0.1, 0.5, 1 and 2 g/l), prepared in the same way, were plotted versus their concentrations. The method was linear at least from 0.05 to 2 g/l, with a detection limit of less than 0.01 g/l. The analytical recoveries were 99.2-102.9% for the different concentrations. Precision studies show coefficients of variation of 3.0-6.3% for the different concentrations.