A multiclass method for the determination of pharmaceuticals in drinking water by solid phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry

In this work, a simple method for the determination of 20 pharmaceuticals of different classes in drinking water using solid phase extraction (SPE) and ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) was developed and validated. Different sorbents, solvents and elution volumes were evaluated. The optimized conditions of the extraction step were the Strata™-X cartridge, samples without pH adjustment but with addition of 0.1% (w/v) of EDTA, eluting solvent 1% (v/v) acetic acid in acetonitrile/methanol 1 : 1 (v/v) and an elution volume of 1 mL. Recovery results were adequate ranging from 70 to 119%, with relative standard deviation (RSD) ≤ 19%. The limits of quantification and detection of the method were from 0.01 to 0.1 μg L−1 and from 0.003 to 0.03 μg L−1, respectively, considered suitable for monitoring of these compounds in drinking water. The proposed method was successfully applied in real samples. Atenolol, carbamazepine and paracetamol were found in some samples at concentrations ≤ 0.027 μg L−1.