A facile lyophilisation-based sample preparation approach for the determination of selected wastewater-borne antiretroviral drugs and metabolites by SFC-MS/MS

The presence of pharmaceuticals in aquatic ecosystems is at the centre-stage of research after the realization that wastewater treatment processes are generally ineffective in the removal of these entities in wastewater given the high likelihood of effluent reuse after disposal. In addition, the continued efforts to scout for new and emerging aquatic contaminants has until recently elicited proliferation of numerous analytical methods for the determination of various (un)known contaminants, since emphasis is now placed in the development of environmentally benign approaches. Herein, we propose and discuss a novel and relatively eco-friendly analytical method based on lyophilization for sample preparation and SFC-MS/MS for the determination of eight (8) antiretroviral drugs (ARVDs) and three (3) metabolites in wastewater samples. This method proved useful in the improvement for the recoveries of lamivudine (3TC) and emtricitabine (FTC) by up to 99% compared to as low as 23% with solid phase extraction (SPE) method. Indeed, previous literature reports has reported poor recoveries for the polar ARVDs, especially on reversed phase (RP) SPE. In contrast, lyophilization promoted matrix effects as evidenced by ion suppression of up to 50% experienced on late eluting compounds. Despite this, lyophilization-SFC-MS/MS method was successfully validated for the quantification of all target analytes, partial exceptions were for ritonavir metabolite (RTVM) which could not be quantified using lyophilization possibly due to lyophilizationinduced losses. Generally, the obtained data has proved that lyophilization is an alternative to SPE and SFC is a suitable alternative to LC.