Determination of polycyclic aromatic hydrocarbons (PAHs) in river water samples from the Vaal Triangle area in South Africa

Abstract

PAHs are fused ring aromatic pollutants some of which are highly carcinogenic to humans and are persistent in the environment. The objective of this study was to develop a suitable extraction method for PAHs from river water samples, identify and quantify the individual compounds. An optimized reverse solid phase extraction (SPE) method was used after conditioning the sorbent to extract and preconcentrate compounds of polycyclic aromatic hydrocarbons (PAHs) in river water samples. The following ten compounds were identified and quantified with a High Performance Liquid Chromatographic technique (HPLC): naphthalene (Naph), acenaphthylene (Ace), phenanthrene (Phe), anthracene (Anth), fluoranthene (Fluo), benzo(b)fluoranthene (BbFl), benzo(k)fluoranthene (BkFl), benzo(a)pyrene (BaPy), dibenzo(a,h)anthracene (DiAn) and indeno(1,2,3-cd)pyrene (InPy). An LC-18 sorbent showed good recoveries after extracting PAHs standard mixture of 1.0 mg/L. The best performing eluting solvent was acetone and very good percentage recoveries that ranged from 97.17–101.18% were obtained for seven compounds. Poor recoveries were also obtained for Fluo (1.03%), BbF1 (0.22%) and BkF1 (0.7%). The standard deviation ranged from 0.05 to 2.26 and the detection limits of less than 0.2 were obtained. Average concentration ranges of PAHs identified within the study area were: Naph (0.0339–0.0382 mg/L) at the Klip river site; Ace (00815–0.0828 mg/L) at Vaal river, (0.0538–0.0591 mg/L) at Klip river and (0.001–0.0073 mg/L) at Vaal barrage; Phe (0.0214–0.0263 mg/L) at Vaal river, (0.0487–0.0521 mg/L) at Klip river and (0.3837–0.4373 mg/L) at Vaal barrage; Anth (0.0073–0.0092 mg/L) at Vaal river, (0.3582–0.4072 mg/L) at Klip river and (0.3457–0.4022 mg/L) at Vaal barrage; Fluo (0.0985–0.1205 mg/L) at Vaal river, (0.0552–0.0593 mg/L) at Klip river and (0.1321–0.1612 mg/L) at Vaal barrage; BbFl (0.0681–0.1151 mg/L) and InPy (0.2561 ± 0.3067 mg/L) at Vaal barrage sites only. Benzo(k)fluoranthene, benzo(a)pyrene and dibenzo(a,h)anthracene were not detected. The obtained data will be useful as baseline information when similar studies are undertaken in the future and could also be useful to policymakers.

Keywords:

• Solid phase extraction
• LC-18 sorbent
• polycyclic aromatic hydrocarbons
• high performance liquid chromatography.

Acknowledgments

The research was supported by Vaal University of Technology and University of South Africa. All analyses were done at SASOL Labs in Sasolburg.