Coupling of comprehensive two-dimensional gas chromatography with quadrupole mass spectrometry: Application to the identification of atmospheric volatile organic compounds

Abstract

Observation data of atmospheric volatile organic compounds (VOCs) are highly needed in air quality assessment, photochemical mechanism study, and emission control policy-making, while it has been a challenge to accurately and comprehensively measure them. Comprehensive two-dimensional gas chromatography (GC×GC) is one of the advanced techniques in analysis of complex mixtures, providing a good choice for measurement of VOCs. However, the requirement for a fast detector limits the application of quadrupole mass spectrometry (qMS) in GC×GC analysis. This paper presents a method of a common qMS detector coupled with GC×GC to the identification of atmospheric VOCs. About 125 VOCs including alkanes, alkenes, aromatics, oxygenated hydrocarbons, and halocarbons were identified in the measurement of standard gas mixtures and/or urban air samples from Beijing. The results were applied to the analysis of GC×GC–FID by one to one correspondence of peaks of the equivalent compounds between the GC×GC–FID and GC×GC–qMS chromatograms, and the retention times of the identified components in GC×GC–FID in turn undertake the qualitative analysis without the further help of MS. The wrap-around phenomenon which may confuse the match of peaks was discussed in detail. The cooperation of GC×GC–FID and GC×GC–qMS which assists the identification makes the GC×GC exploration more affordable and yet practical on both qualitative and quantitative analysis. The method and the identified results can be expanded to analyze other volatiles.