Quantitative determination of 1,2-ethanediol contamination in used diesel lubricating oils by gas chromatography/mass spectrometry

A quantitative method for the determination of 1,2-ethanediol (ethylene glycol) in used diesel lubricating oils is described. The method involves derivatization of the glycol with a proprietary silylating reagent to improve the chromatography of the glycol on a nonpolar capillary column. Separation, detection and quantitative analysis of the trimethylsilyl derivative of the glycol, namely, 2,2,7,7-tetramethyl-3,6-dioxa-2,7-disilaoctane, was carried out using capillary gas chromatography/mass spectrometry. The response of the trimethylsilyl derivative of 1,2-ethanediol was found to be linear over the concentration range studied, that is, from 10 parts per million (ppm) to 10000 ppm (0.001 to 1.0) by weight 1,2-ethanediol in diesel lubricating oil. The minimum detectable quantity of the derivative, using the conditions described in the text, was found to be approximately 2 ppm by weight.