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

• Combination of qMS with GC×GC for identifying atmospheric VOCs.
• Spectra acquisition rate increased to higher than 16 Hz.
• 125 components identified in the standard gas mixtures and air samples.
• Transformation of qualitative results from GC × GC–qMS to GC × GC–FID.

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.