South African Journal of Chemistry
On-line version ISSN 1996-840X
SIBIYA, P. et al. Development and application of solid phase extraction method for polycyclic aromatic hydrocarbons in water samples in Johannesburg area, South Africa. S.Afr.j.chem. (Online) [online]. 2012, vol.65, pp. 206-213. ISSN 1996-840X.
A solid phase extraction (SPE) technique has been developed for the quantitative determination of polyaromatic hydrocarbons (PAHs) in aqueous samples. The SPE technique involved extraction of PAHs from a 100 mL sample containing 10 % methanol as a modifier onto C18 cartridges. 40 % methanol in water was used as conditioning solvent, and 3 mL acetone:THF (1:1) as eluting solvent. After eluting, the extract was reduced to 1 mL under nitrogen and then analyzed by GC-MS. The extraction was optimized for the addition of organic modifier, sample load volume, conditioning solvent, washing solvent and eluting solvent. In order to evaluate the practical applicability of SPE technique, water samples were spiked with the PAHs to give final sample concentrations between 3 and 7µg L-1. Enrichment factors of 81-135 were achieved with relative standard deviations (RSDs) of less than 6 %. Recoveries obtained ranged from 81 to 135 %. Detection limits ranged from 20.0-52.0 ng L-1. The optimized method was validated by analyzing certified reference materials. The optimized method was then applied to spiked real river samples in and around the Johannesburg area, South Africa. The concentrations obtained varied from 22.0 to 1040.0 ng L-1. The RSDs were between 2.3 and 13 %. The overall order of PAHs levels was: phenanthrene > acenaphthene > naphthalene > fluoranthene > pyrene.
Keywords : Solid phase extraction; polycyclic aromatic hydrocarbons; water samples; Johannesburg; South Africa.