On-line solid-phase extraction coupled to hydrophilic interaction chromatography–mass spectrometry for the determination of polar drugs

The present study describes the first fully automated method based on on-line solid-phase extraction (SPE) coupled to hydrophilic interaction chromatography–electrospray-mass spectrometry (HILIC–(ESI)MS) to determine a group of polar drugs that includes illicit drugs (such as cocaine, morphine, codeine and metabolites) and pharmaceuticals in environmental water samples. The SPE was performed using a highly retentive polymeric sorbent. The HILIC separation was optimised and the initial high organic content of the chromatographic mobile phase, was also suitable for the proper on-line elution of the analytes retained in the SPE column and for enhancing the ESI ionisation efficiency. This method allows the loading of samples of up to 250 ml of ultrapure water or 10 ml of environmental water samples spiked at low ng l−1 levels of the analytes. The method yields near 100% recoveries for all the analytes. The method was also validated with environmental water samples with linear ranges from 5 to 1000 ng l−1 and limits of detection ≤2 ng l−1 for most of the compounds.