Ion abundance criteria for gas chromatographic/mass spectrometric environmental analysis.

Mass and intensity calibration of gas chromatograph/mass spectrometer (GC/MS) responses is an important quality assurance issue for chemical analysis. Ion abundance calibration with decafluorotriphenylphosphine (DFTPP) was applied in 1975 to standardize quadrupole spectra to resemble the ion abundances that were obtainable from magnetic sector mass spectrometers. Modern quadrupole mass spectrometers provide significantly greater high-mass sensitivity than allowed under the 1975 study. Thus, those recommendations were reevaluated with 2 approaches. First, an interlaboratory study was conducted using 15 different gas chromatography/mass spectrometry (GC/MS) systems. Second, the U.S. Environmental Protection Agency Contract Laboratory Program (EPA-CLP) quality assurance data base was searched and over 6500 DFTPP tune results were plotted and evaluated. Based on these approaches, updated ion abundance criteria recommendations have been developed, which contemporary instruments can meet, and which meet data quality objectives regarding identification and quantitative analysis of analytes.