Abstract:
Polycyclic Aromatic Hydrocarbons (PAHs) are one of the pollutants in the environment. They are organic compounds that consist of more than one aromatic ring (Kanchanamayoon & Tatrahun 2008). Due to less information forthcoming regarding the levels of PAHs in Vaal area, this study is to evaluate the levels of PAHs in the rivers around Vaal Triangle. Three river sites such as Vaal, Barrage and Klip Rivers were selected to investigate the concentration of polycyclic aromatic hydrocarbons in water. Validation of an analytical method is the process by which it is established by laboratory studies, that the performance characteristics of the method meet the requirements for the intended analytical application. (Stockl et al 2009). The validation parameters tested were, linearity detection limit of quantitation, sensitivity, accuracy, specificity, selectivity, robustness and ruggedness.
PAHs can be determined using High Performance Liquid Chromatography (HPLC) which is a technique for separation, identification and quantification of components in a mixture. The following ten compounds were identified and quantified with a HPLC: naphthalene, acenaphthylene, phenanthrene, anthracene, fluoranthene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(a,h) anthracene and indeno(1,2,3-cd)pyrene. The linear calibration ranges from 0.1-5ppm.The linearity ranges between 0.9993-0.9999.Three reversed sorbent phases (Strata-X, MFC18 and C18) were tested for PAH retention efficiency. An optimised reverse solid phase extraction (SPE) method was used after conditioning the sorbent to extract and collect compounds of polycyclic aromatic hydrocarbons (PAHs) in river water samples. LC18 sorbent showed good recoveries after extracting PAHs standard mixture of 1 mg/l. The best performing eluting solvent was acetonitrile and very good percentage recoveries that ranged from 70% to over 100 % were obtained for eight compounds. Poor recoveries were also obtained for phenanthrene (61%) and benzo(b)fluoranthene (48%). The standard deviation ranged from 0.01 to 0.05 and the detection limits ranging from 0.01 – 0.17 mg/l were obtained. Average concentration ranges of PAHs identified within the study area were: phenanthrene (0.02 – 0.42 mg/l); anthracene (0.37 – 0.39 mg/l), fluoranthene (0.11 – 0.15 mg/l); benzo(b)fluoranthene (0.09 mg/l) and indeno(1,2,3-cd)pyrene (0.26 mg/l). However, naphthalene, acenaphthylene, benzo(k)fluoranthene, benzo(a)pyrene and dibenzo(a,h)anthracene were not detected.
