Multi-family methodologies for the analysis of veterinary pharmaceutical compounds in sediment and sludge samples: comparison among extraction techniques

Abstract

Veterinary drugs are still poorly studied in terms of pathways, release rates and effects on the environment. So, it is necessary to determine their levels in sewage sludge and soil/sediments affected by wastewaters. However, published methodologies deal usually with compounds from only a few classes. In addition, there is a lack of comparisons among the different extraction technologies used. A multi-family methodology for the simultaneous determination of minocycline, oxytetracycline, tetracycline (tetracyclines), enrofloxacin (fluoroquinolone) and ceftiofur (cephalosporin) in sludge and sediment was pursued. Three extraction techniques were compared, vortex agitation, ultrasonic extraction (USE) and microwave assisted extraction. Introduction of solid-phase extraction (SPE) for sample clean-up and pre-concentration was also evaluated. The complex matrix of solid samples posed specific problems, implying the need for individualized approaches for sediments and sludge. For sediments, USE sequential extraction (2 cycles) with methanol–acetone was chosen. LODs, when using SPE, ranged from 0.009 to 0.02 μg g⁻¹. For sludge, samples were sequentially extracted three times by USE with methanol–formic acid. The SPE allowed lowering the limits 10 times ranging from 0.08 to 0.3 μg g⁻¹ for LODs. The method yielded good selectivity and acceptable recovery results. The present methodology resulted in suitable multi-family approaches, less common than the majority of similar processes published.