title: Rapid detection of pesticides not amenable to multi-residue methods by flow injection-tandem mass spectrometry.
abstract: Flow injection combined with tandem mass spectrometry (MS/MS) was investigated for the rapid detection of highly polar pesticides that are not amenable to multi-residue methods because they do not partition into organic solvents and require dedicated chromatographic conditions. The pesticides included in this study were amitrole, chlormequat, cyromazine, daminozide, diquat, ethephon, fosetyl-Al, glufosinate, glyphosate and its metabolite aminomethylphosphonic acid, maleic hydrazide, mepiquat and paraquat. The composition of the flow-injection solvent was optimized to achieve maximum MS/MS sensitivity. Instrumental limits of detection varied between <0.05 and 1 pg. Fruit, vegetable, cereal, milk and kidney samples were extracted with water (1% formic acid in case of paraquat/diquat) and ten times diluted in either methanol/0.1% formic acid, methanol/0.1% ammonia or acetonitrile/0.1% ammonia, depending on the pesticide. The ion suppression observed depended strongly on both the matrix and the pesticide. This could be largely compensated for by matrix-matched calibration, but more accurate quantification was obtained by using isotopically labelled standards (commercially available for most of the pesticides studied). The method detection limits ranged from 0.02 mg/kg for chlormequat and mepiquat to 2 mg/kg for maleic hydrazide and were 0.05-0.2 mg/kg for most other pesticide/matrix combinations. This was sufficiently low to test compliance with EU maximum residue limits for many relevant pesticide/commodity combinations. The method substantially reduces the liquid chromatography-MS/MS capacity demand which for many laboratories is prohibitive for inclusion of these pesticides in their monitoring and surveillance programmes.
authors: RIKILT Institute of Food Safety, Wageningen University and Research Centre, Akkermaalsbos 2, 6708 WB, Wageningen, The Netherlands, hans.mol@wur.nl.
authors: Hans G J
authors: HG
authors: Mol
authors: Ruud C J
authors: RC
authors: van Dam
mesh_terms: D017022:Flow Injection Analysis / Q000379:methods*; D010573:Pesticide Residues / Q000032:analysis*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D010573:Pesticide Residues