Preparation and evaluation of molecularly imprinted polymers as selective SPE sorbents for the determination of cathinones in river water

In this study, a series of molecularly imprinted polymers (MIPs) were synthesised using (1R,2S)-(–)-ephedrine or (1S,2S)-(+)-pseudoephedrine as template, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linking agent. A highly selective and sensitive method using the best performing MIP as sorbent in the solid-phase extraction (SPE) followed by liquid chromatography-high resolution mass spectrometry was established for the enantiomeric determination of five cathinones in river water samples. The SPE parameters (sample loading volume and pH, washing and elution solutions) were optimised so that recoveries and selectivities for the analytes were high. The enantioselectivity of MIPs towards the enantiomers of the analytes during the SPE process was also investigated. Under optimal conditions, the method developed provided satisfactory recoveries ranging from 67.6 to 83.2 % with a negligible matrix effect ranging from −5.5 to 1.8 %. The detection limits ranged from 0.3 to 0.8 ng/L and quantification limits ranged from 1.0 to 2.0 ng/L. The application of the method to the analysis of the river water samples indicated that methedrone and butylone were present at low concentration levels in river water samples.