Green Analytical Methods for Monitoring APIs and Metabolites in Nigerian Wastewater: A Pilot Environmental Risk Study

Abstract

This study presents the development and implementation of green analytical chemistry (GAC) methods for monitoring active pharmaceutical ingredients (APIs) and their metabolites in Nigerian wastewater effluents, with a focus on environmental risk mitigation. The growing prevalence of pharmaceutical residues in aquatic environments poses significant ecological and public health challenges, particularly in regions with inadequate wastewater treatment infrastructure such as Nigeria. Influent and effluent samples were collected from selected wastewater treatment plants in southwestern Nigeria and analyzed using environmentally friendly sample preparation and chromatographic techniques. Specifically, solid-phase microextraction (SPME), microwave-assisted extraction (MAE), and ultrasound-assisted extraction (UAE) were employed to reduce solvent use, minimize hazardous waste, and improve the sustainability of the analytical process. Common APIs, including amoxicillin, ciprofloxacin, paracetamol, and artemether, were detected in varying concentrations across the sampled locations. Method validation demonstrated high recovery rates, excellent linearity, and good precision. The greenness of the developed methods was evaluated using the Analytical GREEnness (AGREE) metric, yielding scores between 0.76 and 0.85—indicating strong compliance with the 12 principles of GAC. Environmental risk was assessed using the Risk Quotient (RQ) approach, revealing that several APIs, especially antibiotics, present moderate to high ecological risks. These findings underscore the importance of integrating GAC techniques into routine environmental monitoring programs. The study recommends the adoption of sustainable analytical practices, infrastructural upgrades, regulatory reform, and capacity-building initiatives to address pharmaceutical pollution in Nigeria effectively.