title: Determination of anthelmintic drug residues in milk using ultra high performance liquid chromatography-tandem mass spectrometry with rapid polarity switching.
abstract: A new UHPLC-MS/MS (ultra high performance liquid chromatography coupled to tandem mass spectrometry) method was developed and validated to detect 38 anthelmintic drug residues, consisting of benzimidazoles, avermectins and flukicides. A modified QuEChERS-type extraction method was developed with an added concentration step to detect most of the analytes at <1 microg kg(-1) levels in milk. Anthelmintic residues were extracted into acetonitrile using magnesium sulphate and sodium chloride to induce liquid-liquid partitioning followed by dispersive solid phase extraction for cleanup. The extract was concentrated into dimethyl sulphoxide, which was used as a keeper to ensure analytes remain in solution. Using rapid polarity switching in electrospray ionisation, a single injection was capable of detecting both positively and negatively charged ions in a 13 min run time. The method was validated at two levels: the unapproved use level and at the maximum residue level (MRL) according to Commission Decision (CD) 2002/657/EC criteria. The decision limit (CCalpha) of the method was in the range of 0.14-1.9 and 11-123 microg kg(-1) for drugs validated at unapproved and MRL levels, respectively. The performance of the method was successfully verified for benzimidazoles and levamisole by participating in a proficiency study.
authors.affiliation: Food Safety Department, Teagasc, Ashtown Food Research Centre, Ashtown, Dublin 15, Ireland.
authors.forename: Michelle
authors.initials: M
authors.lastname: Whelan
authors.forename: Brian
authors.initials: B
authors.lastname: Kinsella
authors.forename: Ambrose
authors.initials: A
authors.lastname: Furey
authors.forename: Mary
authors.initials: M
authors.lastname: Moloney
authors.forename: Helen
authors.initials: H
authors.lastname: Cantwell
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Lehotay
authors.forename: Martin
authors.initials: M
authors.lastname: Danaher
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000032:analysis*; D001562:Benzimidazoles / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004350:Drug Residues / Q000032:analysis*; D007559:Ivermectin / Q000031:analogs & derivatives / Q000032:analysis; D008892:Milk / Q000737:chemistry*; D015233:Models, Statistical; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000871:Anthelmintics; D001562:Benzimidazoles; D007559:Ivermectin; C019264:avermectin