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.