Volatile Organic Compounds Analysis in Drinking Water with Headspace GC/MSD Using Hydrogen Carrier Gas and HydroInert Source

Abstract An Agilent 8890/5977C GC/MSD system coupled with an Agilent 8697 headspace sampler was successfully used with hydrogen carrier gas for the analysis of volatile organic compounds (VOCs) in drinking water. Recent concerns with the price and availability of helium have led laboratories to look for alternative carrier gases for their GC/MS methods. For GC/MS, hydrogen is the best alternative to helium, and offers potential advantages in terms of chromatographic speed and resolution. However, hydrogen is not an inert gas, and may cause chemical reactions in the mass spectrometer electron ionization (EI) source. This can lead to disturbed ion ratios in the mass spectrum, spectral infidelity, peak tailing, and nonlinear calibration for some analytes. Therefore, a new EI source for GC/MS and GC/MS/MS was developed, and optimized for use with hydrogen carrier gas. The new source, named HydroInert, was used in the system evaluated here. In addition to the new source, the chromatographic conditions were optimized to provide separation of 80 volatile compounds in 7 minutes. Standards and samples were analyzed in both scan and SIM data acquisition modes. For the scan data, spectra were deconvoluted with MassHunter Unknowns Analysis software and searched against NIST 20 to assess the spectral fidelity. In both modes, quantitative calibration was performed for the 80 compounds over the range of 0.05 to 25 μg/L. As demonstrated in this note, the system gives excellent results for the analysis of VOCs in drinking water.