Rapid screening of illicit drugs in wastewater based on on-site automated solid phase extraction and portable mass spectrometry techniques

Screening for illicit drugs in urban wastewater provides an important tool for monitoring and tracing the use of illicit drugs, increasingly leaning towards on-site detection of wastewater samples. This study established an on-site detection method for three illicit drugs—ketamine (KET), cocaine (COC), and codeine(COD)—in wastewater, based on an automatic solid-phase extraction device and a portable mass spectrometer. After enrichment and purification of samples using HLB solid-phase extraction cartridges, a portable mass spectrometer equipped with a sub-atmospheric pressure chemical ionization source was used for quantitative analysis of target drugs in selected ion monitoring mode. The solid-phase extraction conditions and parameters of the subatmospheric pressure chemical ionization source were studied and optimized, and the method was evaluated. The results showed that ketamine, cocaine, and codeine exhibited good linearity (R² > 0.99) within the concentration range of 1∼40 μg/L, with limits of detection (LODs) of 0.30∼0.42 μg/L. The recoveries were between 70.52% and 118.56%. This method can be used for on-site rapid screening of illicit drugs in wastewater. Compared to traditional laboratory analysis methods, it reduces sample transportation and storage costs, shortens the detection cycle. Finally, evaluations based on GAPI, AGREE, and BAGI indicators indicated that this method could serve as a green alternative for the screening of illicit drugs in wastewater.