Assessment of nonsteroidal anti-inflammatory drugs by ultrasonic-assisted extraction and GC-MS in Mgeni and Msunduzi river sediments, KwaZulu-Natal, South Africa

Abstract

The occurrence of eight pharmaceuticals was monitored during four seasons (spring, summer, autumn, and winter) along a 250-km stretch of the Msunduzi and Mgeni rivers in KwaZulu-Natal, South Africa. This paper describes an optimized method for the determination of nonsteroidal anti-inflammatory ugs (NSAIDs) in sediments. The method combines ultrasonic, centrifuge, and gas chromatography mass spectrometry for the detection of these drugs in solid samples. Most of the parameters that affect the extraction step were optimized. Solid samples were placed in a centrifuge Tube and extracted with ethyl acetate: acetone (1:1, two cycles), followed by clean-up with Oasis HLB cartridge and derivatization with N, O-bis (trimonthly) trifluoroacetamide (BSTFA). Satisfactory recoveries were obtained ranging from 66 to 130%, depending on the analyte. Precision expressed as RSD (%) (n = 3) was less than 20%for all analytes. The LODs and LOQs were in the range of 0.024 to 1.90 ng g−1 which allowed to be applied in the analysis solid samples in Msunduzi and Mgeni rivers. In the solid samples analyzed, NSAID concentration ranged from not detected to 221 ng g-1