Gas chromatographic mass spectrometric calibration bias

A systematic bias has been observed in the calibration of a number of commercial quadrupole gas chromatographic/mass spectrometric (GC/MS) instruments using conventional internal standard quantification techniques. Response factors between deuterated polynuclear aromatic hydrocarbons and selected analytes are presented for a series of calibration curves generated according to commonty used capillary column semivolatile organic environmental analysis methods. Examples of pronounced response factor trends are given over calibration ranges of <1 order of magnitude. Data are gathered over the course of several years from mass spectrometric systems of differing manufacturer and model. A need to examine and carefully utilize GC/MS calibration curves beyond common practice is demonstrated.