Detection and quantification of acidic drug residues in South African surface water using gas chromatography-mass spectrometry

•Quick easy method for moderately equipped labs in middle income countries.•Acidic drugs can be detected and quantified in surface and waste water samples.•Occurrence of acidic drugs in environmental samples in Southern Africa.

A method was optimized for derivatization, separation, detection and quantification of salicylic acid, acetylsalicylic acid, nalidixic acid, ibuprofen, phenacetin, naproxen, ketoprofen, meclofenamic acid and diclofenac in surface water using gas chromatography-mass spectrometry. For most of the acidic drugs, recovery was in the range 60-110% and the percent standard deviation was below 15% for the entire method, with limits of detection ranging from 0.041 to 1.614 μg L−1. The developed method was applied in the analysis of acidic drugs in Umgeni River system, KwaZulu-Natal South Africa. All of the selected acidic drugs were detected and quantified, their concentration in Umgeni River system ranged from 0.0200 to 68.14 μg L−1.