Development of a technique for determining 18 PAHs in small volume water samples

The capability within the BGS Laboratories for the determination of PAHs by HPLC was extended by undertaking a development of technique investigation (MaDCap). As a result, it is now possible to determine 18 PAHs by the sensitive and selective means of HPLC coupled with fluorescence detection. These PAHs comprise 15 of the 16 USEPA PAH (acenaphthylene cannot be determined because it is not sufficiently fluorescent), 1- and 2- methylnaphthalenes together with the biogenically significant PAH, perylene. Subsequent further development of a technique, known as Silicone Rod Sorptive Extraction (SRSE), permitting the extraction and concentration of PAHs from small volume water samples, resulted in its successful application to the determination of the 18 PAHs in five samples of porewater. These porewaters had been obtained by the high pressure squeezing of Oxford and Corallian Clay core material in a heavy-duty pressure apparatus designed at BGS. Previously, porewater samples have been dispatched from BGS to a contract analytical laboratory where it was found that standard methods for PAH analysis were not suitable for the acquisition of meaningful data from limited sample volumes. Indeed, the determination of PAHs in small volumes of natural waters represents a substantial analytical challenge. This report details the development of a technique to successfully surmount that challenge.