Paraffin Wax Spill Identification by GC–FID and GC–MS

Abstract Paraffin wax spills from tanker discharges commonly impact shorelines. The need to compare paraffin spill samples and cargo reference samples has led to the development and evaluation of a method for paraffin wax spill identification that conforms to the CEN method for oil spill identification. Gas chromatography-flame ionization detection (GC-FID) data have been used to compare paraffin profiles by using a novel weighted mean versus standard deviation graph, conventional GC-Percentage Weathering plots (GC-PW) plots and n -alkane ratios. Gas chromatography-mass spectrometry (GC-MS) data of steranes, hopanes, n -alkanes, branched alkanes and compounds of two unknown compound series not related to the n -alkanes, have been selected for defining diagnostic ratios appropriate for paraffin. The resulting GC–MS data are used to compare samples visually and by means of MS-Percentage Weathering (MS–PW) plots and compound ratios. The method has been tested with samples from several paraffin spills and ten paraffin wax samples previously used in an inter-laboratory round robin study applying GC–FID, GC–MS, and gas chromatography coupled to isotope ratio mass spectrometry. The results show that paraffin waxes differ significantly in composition and that heterogeneities within samples can arise when long chain n -alkanes become redistributed, while wax is cooling from a fluid to a solid. Based on the analytical results of the developed method a match between a paraffin spill sample collected from a Dutch beach and a cargo reference sample is concluded.