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.
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Date
2022
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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).
Description
Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.