The use of SPME and GC-MS for the chemical characterisation and assessment of PAH pollution in aqueous environmental samples

In this study, direct solid-phase microextraction (DISPME), followed by capillary gas chromatography (GC) and mass spectrometry (MS) in the selected ion storage (SIS) mode was investigated for the determination of polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues in environmental water samples. It was found that several factors affected the amount absorbed with a single stage extraction, such as the degree of alkylation, fiber condition, absorption time, sample pH, sample matrix, sample temperature, agitation method etc. The technique of multiple extractions (MESPME) was investigated and found to compensate for variations in analytical conditions or sample matrix. The linearity of spiked PAH samples was established in the low concentration range with correlation coefficients of about 0.99. Relative standard deviations (%RSD) of between 1.6 and 17.8% were obtained for relative response factors (RRFs). The limits of detection were estimated at the pg/cm(3) levels that were considerably lower than the maximum concentration level (MCL) specified by the United States Environmental Protection Agency (USEPA). The results demonstrate the potential of MESPME for screening PAHs in environmental waters. The method was also developed to include the quantification of alkyl substituted PAHs which is important for interpretative methods such as chemical fingerprinting (source identification) and hazard, exposure and risk characterisation.