title: Development and independent laboratory validation of a simple method for the determination of paraquat and diquat in potato, cereals and pulses.
abstract: A new sensitive, fast and robust method for the determination of paraquat and diquat residues in potatoes, cereals and pulses is presented. Different extraction conditions (solvent, time and temperature) have been evaluated using barley grain, potatoes and dry lentils containing incurred residues of diquat and paraquat. The finalised procedure involves extraction with a mixture of methanol/water/hydrochloric acid at 80 °C and analysis by liquid chromatography-tandem mass spectrometry. Diquat D4 and Paraquat D6 internal standards were added to the test portions prior to extraction. A small-scale inter-laboratory validation of the developed method for diquat and paraquat using potato and barley samples was conducted by three laboratories. The precision and accuracy of the method were determined from recovery experiments (five replicates) at 0.01 and 0.1 mg kg(-1). The recoveries obtained (n = 180) were in the range of 92-120 % with associated relative standard deviation (RSD) between 1.4-10 % for all compound/commodity/spiking concentration combinations.
authors.affiliation: Chemisches und Veterinäruntersuchungsamt Stuttgart, Fellbach, Germany. Diana.Kolberg@cvuas.bwl.de
authors.forename: Diana I S
authors.initials: DI
authors.lastname: Kolberg
authors.forename: Dorothea
authors.initials: D
authors.lastname: Mack
authors.forename: Michelangelo
authors.initials: M
authors.lastname: Anastassiades
authors.forename: Michael T
authors.initials: MT
authors.lastname: Hetmanski
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Fussell
authors.forename: Thijs
authors.initials: T
authors.lastname: Meijer
authors.forename: Hans G J
authors.initials: HG
authors.lastname: Mol
mesh_terms: D002853:Chromatography, Liquid; D004178:Diquat / Q000032:analysis*; D002523:Edible Grain / Q000737:chemistry*; D007887:Fabaceae / Q000737:chemistry*; D005504:Food Analysis / Q000379:methods*; D057230:Limit of Detection; D013058:Mass Spectrometry; D015394:Molecular Structure; D010269:Paraquat / Q000032:analysis*; D011198:Solanum tuberosum / Q000737:chemistry*
chemical_list: D004178:Diquat; D010269:Paraquat