Multi-residue determination of the sorption of illicit drugs and pharmaceuticals to wastewater suspended particulate matter using pressurised liquid extraction, solid phase extraction and liquid chromatography coupled with tandem mass spectrometry

Presented is the first comprehensive study of drugs of abuse on suspended particulate matter (SPM) in wastewater. Analysis of SPM is crucial to prevent the under-reporting of the levels of analyte that may be present in wastewater. Analytical methods to date analyse the aqueous part of wastewater samples only, removing SPM through the use of filtration or centrifugation. The development of an analytical method to determine 60 compounds on SPM using a combination of pressurised liquid extraction, solid phase extraction and liquid chromatography coupled with tandem mass spectrometry (PLE-SPE-LC–MS/MS) is reported. The range of compounds monitored included stimulants, opioid and morphine derivatives, benzodiazepines, antidepressants, dissociative anaesthetics, drug precursors, and their metabolites. The method was successfully validated (parameters studied: linearity and range, recovery, accuracy, reproducibility, repeatability, matrix effects, and limits of detection and quantification). The developed methodology was applied to SPM samples collected at three wastewater treatment plants in the UK. The average proportion of analyte on SPM as opposed to in the aqueous phase was <5% for several compounds including cocaine, benzoylecgonine, MDMA, and ketamine; whereas the proportion was >10% with regard to methadone, EDDP, EMDP, BZP, fentanyl, nortramadol, norpropoxyphene, sildenafil and all antidepressants (dosulepin, amitriptyline, nortriptyline, fluoxetine and norfluoxetine). Consequently, the lack of SPM analysis in wastewater sampling protocol could lead to the under-reporting of the measured concentration of some compounds.

► First multi-residue PLE-SPE-LC–MS/MS method to analyse drugs of abuse in suspended particulate matter (SPM) in wastewater.
► 60 drugs of abuse and associated metabolites were monitored.
► Method validation: MQLs: 0.06–20 ng g−1; precision: <20%; accuracy: ±18%; PLE recovery: ≥56%.
► The average proportion of several antidepressants on SPM was >40%.
► Lack of SPM analysis could lead to under-reporting of concentrations of certain drugs in wastewater.