Determination of diazepam and its active metabolites in aquatic products and aquaculture environments using modified QuEChERS-based UPLC-MS/MS†

Abstract

In recent years, the residue of psychotropic drugs such as diazepam in aquatic products has attracted widespread attention and is one of the important hidden dangers to the quality and safety of agricultural products. This study developed a modified QuEChERS method combined with UPLC-MS/MS to determine the residues of diazepam and its active metabolites, nordiazepam, oxazepam, and temazepam, in aquatic products and aquaculture environments. The important variables of the QuEChERS procedure were screened and optimized through single-factor experiments and response surface methodology. The recoveries of analytes in five aquatic products, pond water, and sediment were 87.4–97.8%, 90.4–96.4%, and 85.2–94.7%, respectively, with relative standard deviations of less than 15%. The limits of quantification were 0.1 μg kg⁻¹ for the four analytes in aquatic products and sediments, and 5 ng L⁻¹ in pond water. This method has been successfully applied to the analysis of diazepam and its active metabolite residues in 28 freshwater aquaculture farms in South China. The detected concentrations of the four analytes in aquatic products, sediments and pond water were 0.18–3.03 μg kg⁻¹, 0.21–17.5 μg kg⁻¹ and 5.56–391 ng L⁻¹, respectively. The illegal abuse of diazepam in fishing bait may be an important source of pollution in aquatic products. The risk assessment results showed that the residues of diazepam in aquaculture posed an acceptable risk to human health and a medium risk to the ecosystem. These results confirmed that the established method is suitable for the simultaneous analysis of diazepam and its active metabolites in aquatic products and aquaculture environments.