Development of an isotope-dilution gas chromatographic-mass spectrometric method for the analysis of polycyclic aromatic compounds in environmental matrices

An isotope-dilution GC-MS (GC-IDMS) method for the analysis of polycyclic aromatic hydrocarbons (PAHs) in various environmental matrices, including soils, sediments and an extended application to air particulate, has been developed. This method allows for the quantification of each target analyte against its isotope-labelled analogue as well as for the correction of analyte recovery during sample preparation and analysis. Using isotope-dilution mass spectrometric analysis, the isotope-labelled internal standards can significantly reduce systematic error (bias) from several sources including sample stability prior to analysis, analyte loss during both the extraction procedure and post-extraction sample workup and from the calibration procedure. Sample analysis and quantification was carried out using a multi-point calibration technique with continuing single-point calibration (daily single-point checks of the calibration) in order to assess daily instrumental performance; various other new quality control measures have also been employed. Faster methods of gas chromatographic analysis were evaluated using different types of GC columns, stationary phases and methods of detection. Overall, this method has improved the quality and accuracy of PAH data produced and has significantly reduced the time required for sample preparation.