Real-Time Speciation of Ethylbenzene from the Xylenes Using SIFT-MS

Martin Perkins

11th September 2019

Ethyl benzene and the Xylenes are part of a group of compounds known as BTEX (benzene, toluene and xylenes) and originate in the environment from a number of sources. This group of compounds may pose potential human health risk, in particular from inhalation and therefore are included in environmental and occupational monitoring programs. Direct mass spectrometry (DMS) techniques traditionally have struggled to distinguish ethylbenzene from the xylene isomers, so measurement has been reported as a total concentration of “ethylbenzene plus xylenes”. However, regulations are increasingly calling for separated measurements due to different occupational exposure limits.  Previously this would have required chromatographic separation of the isomers using specific gas chromatographic methods. These methods require static (grab) samples to be taken at different time points, rather than being able to perform analysis in real time as with direct MS approaches. This application note highlights the ability of SIFT-MS to speciate ethylbenzene from the xylenes in real time, using O2+ and a simple calibration approach.


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