Gas chromatography/miniaturized time-of-flight mass spectrometry technique for high-throughput quantitative on-site field analysis

Abstract

Previously, we reviewed several mass spectrometers designed for field analysis, also known as harsh mass spectrometers. The majority of these instruments are focused on the instrument footprint size and weight, which compromise the performance, for instance, in terms of mass-resolving power. Our recent work employed a shoebox-size (mini-tower personal computer size) high-resolving-power mass analyzer equipped with a robust gas chromatograph in the firm field, which successfully monitored the soil-gas compositional changes on-the-fly in real time. We evaluated the system performance for mass accuracy, self-validation testing for analyte peaks, and quantitative precision through long-term continuous data acquisitions of 1429 replicates of model gas samples for 48 h. The observed mass drift was 4 mDa, which was compensated within 0.45 mDa using a novel algorithm without the addition of mass reference materials. In addition, the optimized algorithm for high-resolution ion chromatogram extraction for this application was evaluated. Results indicated that the proposed method limited the chromatographic peak area variance. The coefficient of variance (CV) for determining CO2 amounts for the 1429 sample runs was 8.6%. Furthermore, the CO2 average retention time was 48.06 ± 0.29 s (CV = 0.61%), average number of theoretical plates was 3500, and asymmetry factor was 1.09.