Improvement in the detection of impurities affecting ethylene glycol UV transmittance by gas chromatography–mass spectrometry

A method was developed for the detection of trace impurities affecting ethylene glycol UV transmittance, using gas chromatography–mass spectrometry in the selective ion monitoring mode. Four 1,2-cyclopentanediones were identified in commercial ethylene glycol as well as in several ethylene glycol plant streams, including 3-methyl-1,2-cyclopentanedione, 3,5-dimethyl-1,2-cyclopentanedione, 3,4-dimethyl-1,2-cyclopentanedione and 3-ethyl-1,2-cyclopentanedione. Quantification of the first three compounds was achieved by monitoring the molecular ion. This method requires no sample preparation and can detect the compounds of interest as low as 0.1 μg ml−1. As a simple and rapid method, it can be used in tracing these 1,2-cyclopentanediones in glycol plants.