Zhu, J., Nones, C., Li, Y., Milligan, D. et al., "Ultra-Trace Real Time VOC Measurements by SIFT-MS for VIAQ," SAE Int. J. Engines 10(4):2017, doi:10.4271/2017-01-0989.
Vehicle interior air quality (VIAQ) measurements are currently conducted using the offline techniques GC/MS and HPLC. To improve throughput, speed of analysis, and enable online measurement, specialized instruments are being developed. These instruments promise to reduce testing cost and provide shortened analysis times at comparable accuracy to the current state of the art offline instruments and methods. This work compares GCMS/HPLC to the Voice200ultra, a specialized real-time instrument utilizing the technique selected ion flow tube mass spectrometry (SIFT-MS). The Voice200ultra is a real-time mass spectrometer that measures volatile organic compounds (VOCs) in air down to the parts-per-trillion level by volume (pptv). It provides instantaneous, quantifiable results with high selectivity and sensitivity using soft chemical ionization. The VOC measurement capabilities of the Voice200ultra is being compared to gas chromatography-mass spectrometry (GC/MS) and high-performance liquid chromatography (HPLC), which are the internationally accepted industry standard. In this study, we compare the analytical capabilities of SIFT-MS to the accepted standard measurement techniques by GCMS/HPLC by measuring the VOCs in new vehicle interiors. We quantify formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, xylene, styrene, and acrolein (the eight chemicals found in the GB list specified by the Chinese government) as well as many other compounds, including acetone and butanone. The comparability between SIFT-MS and GCMS/HPLC is excellent with an average R2 values of at least 0.89 for all compounds excluding formaldehyde and acrolein. This excellent correlation demonstrates that the Voice200ultra is able to accurately measure these target species with excellent selectivity in the complex sample matrix of a new car cabin interior. Levels of acrolein and formaldehyde as measured by HPLC were extremely low and the lack of correlation for these two compounds is attributed to the intrinsic issues with the HPLC technique for the measurement of these compounds.