Comparison of Four Extraction Methods for the Determination of Veterinary Pharmaceuticals in Sediment

In this work extraction by agitation (EA), ultrasound solvent extraction (USE), microwave assisted extraction (MAE) and pressurized liquid extraction (PLE) followed by high performance liquid chromatography with diode array detector (HPLC–DAD) for the determination of eight veterinary pharmaceuticals from different structural groups including one macrolide (tylosine), three anthelmintics (albendazole, febantel and levamisole), two anesthetics (lidocaine and procaine) and two steroidal hormones (hydrocortisone and dexamethasone) in sediment is described. Selected pharmaceuticals are widely used in veterinary practice in Croatia and in the whole world. Since they belong to different structure groups the usage of routine methods is not effective for their extraction from a complex sediment sample. Also, until now no article has been published for systematic extraction of named pharmaceuticals from sediment sample by different extraction methods. EA, USE, MAE and PLE have been optimized regarding different characteristic parameters such as sediment mass, extraction solvent, solvent volume, agitation frequency, power of ultrasound bath, extraction duration, extraction temperature and contact time between sediment and solvent. After extraction, pharmaceuticals were analyzed by HPLC–DAD using C18 stationary phase. HPLC–DAD–EA, HPLC-USE, HPLC–DAD-MAE and HPLC–DAD–PLE methods were validated in terms of selectivity, specificity, linearity, sensitivity, method detection limit (MDL) and quantification (MQL), repeatability, recovery and stability of a standard solution. Recoveries of selected pharmaceuticals from spiked sediment samples were generally higher than 50 %. However, dexamethasone and hydrocortisone showed lower recoveries due to their significantly different molecule structure. This paper shows the ability of simultaneous extraction and analysis of all selected pharmaceuticals by four different extraction methods in complex sediment sample followed by relatively affordable and sensitive HPLC–DAD method.