title: Determination of phosphine in plant materials: method optimization and validation in interlaboratory comparison tests.
abstract: The optimization and validation of a method for the determination of phosphine in plant materials are described. The method is based on headspace sampling over the sample heated in 5% sulfuric acid. Critical factors such as sample amount, equilibration conditions, method of quantitation, and matrix effects are discussed, and validation data are presented. Grinding of coarse samples does not lead to lower results and is a prerequisite for standard addition experiments, which present the most reliable approach for quantitation because of notable matrix effects. Two interlaboratory comparisons showed that results varied considerably and that an uncertainty of measurement of about 50% has to be assessed. Flame photometric and mass spectrometric detection gave similar results. The proposed method is well reproducible within one laboratory, and results from the authors' laboratories using different injection and detection techniques are very close to each other. The considerable variation in the interlaboratory comparison shows that this analysis is still challenging in practice and further proficiency testing is needed.
authors.affiliation: COOP Central Laboratory, Head Quarters, Gottesackerstrasse 4, 4133 Pratteln, Switzerland.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Amrein
authors.forename: Lara
authors.initials: L
authors.lastname: Ringier
authors.forename: Nathalie
authors.initials: N
authors.lastname: Amstein
authors.forename: Laurence
authors.initials: L
authors.lastname: Clerc
authors.forename: Sabine
authors.initials: S
authors.lastname: Bernauer
authors.forename: Thomas
authors.initials: T
authors.lastname: Baumgartner
authors.forename: Bernard
authors.initials: B
authors.lastname: Roux
authors.forename: Thomas
authors.initials: T
authors.lastname: Stebler
authors.forename: Markus
authors.initials: M
authors.lastname: Niederer
mesh_terms: D002849:Chromatography, Gas / Q000379:methods* / Q000592:standards; D007753:Laboratories / Q000592:standards*; D010720:Phosphines / Q000032:analysis*; D010936:Plant Extracts / Q000032:analysis*; D010944:Plants / Q000737:chemistry*
chemical_list: D010720:Phosphines; D010936:Plant Extracts; C044646:phosphine