title: Liquid chromatography-tandem mass spectrometric methods for the determination of spinosad, thiacloprid and pyridalyl in spring onions and estimation of their pre-harvest interval values.
abstract: Two liquid chromatography-tandem mass spectrometric methods were developed and validated to determine spinosyn A and D, thiacloprid and pyridalyl in spring onions cultivated under Egyptian field conditions. The degradation rates, the pre-harvest interval (PHI) values and the half-life values of the three pesticides were estimated. QuEChERS was used for sample preparation and the separation was performed on an X-Bridge C18 column with ACN-formic acid 0.1% as the mobile phase. Linear range, method detection limits (MDLs), precision, recovery and matrix effects were estimated. The multi-residue MDLs ranged from 0.02μg/kg (spinosyn A & D) to 0.05μg/kg for pyridalyl. All the investigated pesticides showed high degradation rates. For spinosad the half-life value was 1.2days, for thiacloprid it reached 2.2days and for pyridalyl 4.4days. Furthermore, the calculated PHI values, according to the maximum residue levels set by the EU, were 0days for spinosad, 9.8days for thiacloprid and 39.4days for pyridalyl.
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zographou, 15771 Athens, Greece. Electronic address: mdasenaki@chem.uoa.gr.
authors.forename: Marilena E
authors.initials: ME
authors.lastname: Dasenaki
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zographou, 15771 Athens, Greece. Electronic address: abletsou@chem.uoa.gr.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Bletsou
authors.affiliation: Plant Protection Department, Faculty of Agriculture, Ain Shams University, P.O. Box 68, Hadayek Shoubra, Cairo 11241, Egypt. Electronic address: asy3012@yahoo.com.
authors.forename: Ahmad H
authors.initials: AH
authors.lastname: Hanafi
authors.affiliation: Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zographou, 15771 Athens, Greece. Electronic address: ntho@chem.uoa.gr.
authors.forename: Nikolaos S
authors.initials: NS
authors.lastname: Thomaidis
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods*; D004338:Drug Combinations; D018942:Macrolides / Q000737:chemistry*; D000073943:Neonicotinoids; D019697:Onions / Q000737:chemistry*; D010575:Pesticides / Q000032:analysis*; D010647:Phenyl Ethers / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013843:Thiazines / Q000737:chemistry*
chemical_list: D004338:Drug Combinations; D018942:Macrolides; D000073943:Neonicotinoids; D010575:Pesticides; D010647:Phenyl Ethers; D011725:Pyridines; D013843:Thiazines; C417209:thiacloprid; C418569:S 1812; C415329:spinosad
keywords: Degradation rate; Half-life; LC–MS/MS; Multi-residue; Pesticides; Pre harvest interval; Spring onions