From multi-residue screening to target analysis of pharmaceuticals in water: development of a new approach based on magnetic sector mass spectrometry and application in the Nairobi River basin, Kenya

This paper presents the development and application of a new multi-residue analytical method providing the first data on the environmental occurrence of human pharmaceuticals in Africa, particularly the Nairobi River basin (Kenya). Based on pharmaceutical consumption data available for the Nairobi region, 43 'priority' pharmaceutically active ingredients (PAIs) were selected for this study. On the basis of magnetic sector high-resolution mass spectrometry, a new methodology involving both full-scan screening and selective target analysis has been developed to investigate the presence of the defined priority PAIs. Subsequent analysis of the corresponding standard compounds provided the full confirmation and indicative concentrations (low ng/L-high μg/L) of 10 human PAIs in the Nairobi River. The detected compounds belong to different classes, i.e. antibiotics, analgesic/anti-inflammatory and anti-epileptic drugs, antimalarials and antiretrovirals. Ibuprofen, paracetamol, sulfamethoxazole and zidovudine showed to be the most concentrated PAIs (about 10-30 μg/L). The concentration of the antiretrovirals (lamivudine, zidovudine and nevirapine) is clearly higher than those reported in the literature, although environmental data on this class of PAIs are still very limited. To the best of our knowledge, this is the first study that provides evidence of detection of lamivudine in surface water. The presented unique data on the occurrence of selected PAIs in the aquatic environment of Africa clearly show that the high prevalence of specific diseases like HIV/AIDS infection in developing countries might result in a different pattern of PAIs in environmental waters compared to the more developed regions.