Occurrence of Selected Pharmaceuticals in the East London Coastline Encompassing Major Rivers, Estuaries, and Seawater in the Eastern Cape Province of South Africa

Abstract

This study investigated the occurrence of ibuprofen, naproxen, sulfamethoxazole, trimethoprim, and efavirenz in water resources (river, estuarine, and sea waters) of the East London coastline, South Africa. These pharmaceuticals were previously reported to be dominant in wastewater and inland rivers of South Africa. Hence, it is important to monitor their occurrence in the coastal and marine environment. The pharmaceuticals of interest were extracted with a solid-phase extraction method and analyzed by using a liquid chromatography-quadrupole time-of-flight mass spectrometry instrument. The analytical method was validated by spiking the environmental samples with a mixture of pharmaceuticals at two concentration levels (5 and 15 μg L^-1). The analytical method yielded acceptable recoveries ranging from 75 to 107%, with method quantitation limits from 0.16 to 9.44 ng of L^-1. All five targeted pharmaceuticals were detected in seawater samples, with ibuprofen recording the highest concentration of 90 ng L^-1. However, it was efavirenz and sulfamethoxazole with the highest concentrations of 572 and 60 ng L^-1, respectively, in the Gonubie River that showed high ecotoxicological risks toward the aquatic organisms. There were no risks associated with the occurrence of other targeted pharmaceuticals. The suspect screening showed the occurrence of 57 additional pharmaceuticals in samples, with antibiotics being more dominant. The results of the present study demonstrate a need to perform a more robust investigation on the occurrence of a wide range of pharmaceuticals along the South African coasts.