Submitted to: Analytica Chimica Acta
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2008
Publication Date: 1/5/2009
Citation: Kinsella, B., Lehotay, S.J., Mastovska, K., Lightfield, A.R., Furey, A., Danaher, M. 2009. New Method for the Analysis of Flukicide and Other Anthelmintic Residues in Bovine Milk and Liver using Liquid Chromatography - Tandem Mass Spectrometry. Anal. Chim. Acta. (637):196-207. Interpretive Summary: The analysis of veterinary drug residues in animal-derived foods, such as beef, is an important function of regulatory bodies worldwide to ensure the proper usage of the chemicals by producers and to help ensure food safety. Currently, inefficient analytical monitoring methods are used by many regulatory agencies needs to be updated using more efficient and effective modern approaches. In the case of worm controlling agents, known as anthelmintics, no analytical method had existed that could detect all of them in a single, efficient procedure. This research project fulfilled that need by being able to detect essentially all known registered anthelmintics and others that are not registered for use on cattle. The method was validated thoroughly to demonstrate its satisfactory performance in regulatory applications. In the future, it will very likely be used by regulatory laboratories around the world to monitor anthelmintic residues in beef.
Technical Abstract: A liquid chromatographic-tandem mass spectrometric (LC-MS/MS) multi-residue method for the simultaneous quantification and identification of 38 residues of the most widely used anthelmintic veterinary drugs (including benzimidazoles, macrocyclic lactones, and flukicides) in milk and liver has been developed and validated. For sample preparation, we used a simple modification of the QuEChERS method, which was initially developed for pesticide residue analysis. The method involved extracting sample (10 g) with acetonitrile (10 mL), followed by phase separation from water (salting out) with MgSO4:NaCl (4:1, w/w). After centrifugation, an aliquot of the extract (1 mL) was purified by dispersive solid phase extraction with MgSO4 (150 mg) and C18 (50 mg), prior to LC-MS/MS analysis. Two injections of the same extract were required with the LC-MS/MS instrument to cover the 30 electrospray positive and 8 electrospray negative analytes. The limit of quantitation of the method was 5 ug kg-1 for 37 analytes (and 10 ug kg-1 for dichlorvos). The method was successfully validated according to the 2002/657/EC guidelines. Recovery of analytes was typically in the 70 to 120% range, with repeatabilities and reproducibilities typically <15% in milk and <20% in liver.