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

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