title: Measurement uncertainty associated with sample processing of oranges and tomatoes for pesticide residue analysis.
abstract: The homogeneity of analytical samples and the stability of pesticides during the sample processing of oranges and tomatoes were evaluated. The mean concentrations of 14C-labeled chlorpyrifos in analytical portions (subsamples) after processing show that homogeneity is dependent on sample type as well as the processing procedure. The homogeneity of analytical samples of tomatoes processed cryogenically was much better than those processed at ambient temperature. For tomatoes, the minimum analytical portion masses required for between-analytical portion variation of < 0.3 Ho were 110 and 5 g for processing at ambient and cryogenic temperatures, respectively. Results for orange showed that analytical portion sizes of 5 g provided sufficient homogeneity from both sample processing procedures. Assessments of pesticide stability demonstrated that most were relatively stable during processing at either ambient or cryogenic temperatures. However, some pesticides, including dichlofluanid, chlorothalonil, tolylfluanid, and dicloran, appeared to suffer much greater losses (>20%) during processing at ambient temperature. For these analytes, loss is interpreted as chemical degradation.
authors.affiliation: Department for Environment, Food and Rural Affairs, Central Science Laboratory, Sand Hutton, York YO41 1LZ, United Kingdom. r.fussell@csl.gov.uk
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Fussell
authors.forename: Michael T
authors.initials: MT
authors.lastname: Hetmanski
authors.forename: Roy
authors.initials: R
authors.lastname: Macarthur
authors.forename: Dawn
authors.initials: D
authors.lastname: Findlay
authors.forename: Frankie
authors.initials: F
authors.lastname: Smith
authors.forename: Arpad
authors.initials: A
authors.lastname: Ambrus
authors.forename: Peter Josef
authors.initials: PJ
authors.lastname: Brodesser
mesh_terms: D032084:Citrus sinensis / Q000737:chemistry*; D004355:Drug Stability; D005511:Food Handling / Q000379:methods*; D005615:Freezing; D005638:Fruit / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D018551:Solanum lycopersicum / Q000737:chemistry*; D010573:Pesticide Residues / Q000032:analysis*; D012680:Sensitivity and Specificity
chemical_list: D010573:Pesticide Residues