Determination of acidic pharmaceuticals, antibiotics and ivermectin in river sediment using liquid chromatography–tandem mass spectrometry

Analytical methods have been developed for the determination of eight acidic pharmaceuticals and two metabolites, seven antibiotics and the parasiticide ivermectin in a selected river sediment. The sediments were solvent extracted with ultrasonic assistance. A solid phase extraction (SPE) clean-up step was performed thereafter. The acidic compounds clofibric acid, diclofenac, fenoprofen, gemfibrozil, ibuprofen, 2-hydroxy-ibuprofen, indomethacin, ketoprofen, naproxen and the parasiticide ivermectin were measured in the negative mode by LC–APCI–tandem MS, whereas the antibiotics clarithromycin, erythromycin, roxithromycin, sulfadiazine, sulfamethazine, sulfamethoxazole and trimethoprim were detected in the positive mode by LC–ESI–tandem MS. Bezafibrate could not be determined in the sediment using the method developed. The limit of quantification (LOQ) ranged from 0.4 to 8 ng g−1 for the acidic pharmaceuticals, sulfadiazine and ivermectin and was 20 ng g−1 for the other antibiotics.