Method development and application: solid phase extraction (SPE), ultrasonic extraction (UE) and soxhlet extraction (SE) for the determination of antiretroviral drugs in river water, wastewater, sludge, soil and sediment.

Abstract

Antiretroviral drugs (ARVs) are a group of pharmaceuticals that have been recognized to be present in the environment and most of them have been reported to be environmentally persistent. However, most studies have documented their concentration levels in the aqueous matrices and not solid matrices. This project involved the optimization of Soxhlet extraction (SE), ultrasonic extraction (UE) and solid-phase extraction (SPE) methods followed by liquid chromatography-photodiode array (LC-PDA) method for the analysis of abacavir, nevirapine and efavirenz in wastewater, river water, sludge, sediment and soil samples. The methods validation was based on linearity, limits of detection (LOD), limit of quantification (LOQ) and percentage recoveries. Good linearity was obtained for all the studied ARV drugs with R2 values ranging from 0.9979 - 0. 9984. The recoveries, LOD and LOQ ranged from 71 - 112%, 0.7 - 0.8 μg/L and 2.07 - 2.36 μg/L, respectively for SPE. For SE they were 79 - 108%, 0.8 - 0.9 μg/kg and 2.4 - 2.8 μg/kg, respectively, while for UE they were 61 - 104%, 1.6 - 2.3 μg/kg and 4.9 - 7.0 μg/kg, respectively. These findings revealed that the methods are accurate and applicable for the monitoring of the selected ARV drugs in environmental samples. Also, they revealed that SE has high accuracy and sensitivity compared to UE due to its lower LOD, LOQ and recoveries. The concentrations detected in real samples were 8.39 - 102 μg/L in river water, 2.47 - 814 μg/L in wastewater, and 19.8 - 6759 μg/L in sludge. The seasonal variation affect the detected ARV concentrations as lower levels were observed in spring season compared to winter. The concentrations of ARV found in sediments and soil were 22.8 - 98.9 μg/kg and 15.4 - 138 μg/kg and. The detection of ARVs in the environmental samples raise great concerns, for example, drug resistance due to build of drugs in water, soil, etc. This shows the significance of continuously monitoring these compounds that find their way to rivers including rivers (surrounding surfaces) that are used as vessels for waste including untreated and partially treated sewage from the municipalities (Hinrichsen and Tacio, 2002), that leach into surface water during various activities. Hence, large quantities of various pollutants including pharmaceuticals and antibiotics have been found in sediments, soils and surface water worldwide in which the major sources have been reported to be industries (Archer et al., 2017b) and wastewater treatment plants (WWTPs) final effluents (Paiga et al., 2016).