Determination of illicit drugs in sediments using a modified QuEChERS method coupled with UPLC-MS/MS

The occurrence of illicit drugs in water has been extensively reported around the world, however, limited data are available in sediments, probably due to the lack of effective and robust analytical methods. This research established a sensitive method for determining 12 illicit drugs, including amphetamine, methamphetamine, methcathinone, ephedrine, 3,4-methylenedioxy-amphetamine, 3,4-methylenedioxy-n-methamphetamine, norketamine, ketamine, benzoylecgonine, codeine, cocaine, and methadone in sediments. The combination of salt and solution (extraction step) and adsorbents (purification step) in the QuEChERS method was optimized to enhance the applicability and reliability of the analytical approach, which was subsequently combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The developed method demonstrated satisfactory linearity (R² > 0.995) within 0.1 to 50 ng/g dry weight (dw), with limits of detection and quantification ranging from 0.0077 to 0.0299 ng/g dw and 0.0255 to 0.0996 ng/g dw, respectively. Recoveries of target drugs ranged from 60.5 % to 114.9 %, with intra-day and inter-day relative standard deviations below 10.9 % and 12.3 %, respectively, which are within the acceptable limits. Application of the validated method to sediments from the Beiyunhe River Basin, China revealed the presence of nine out of twelve targeted drugs. Total drug concentrations ranged from 0.12 to 1.18 ng/g dw, with ephedrine being predominant, followed by amphetamine and methadone. Ecological risk assessments indicated low biological hazards from the detected drugs to aquatic ecosystems. However, due to their high polarity and biological activity, continued attention to the ecological risks of illicit drugs would provide greater reassurance. This research presents the first application of QuEChERS for extracting illicit drugs from sediments. The optimized method elucidates these emerging contaminants' behavior and facilitates accurate environmental risk assessments. Due to its high sensitivity, good recovery and precision, the method is well-suited to routine monitoring of trace-level illicit drugs in complex sediment matrices.