title: Estimation of sampling uncertainty for pesticide residues in root vegetable crops.
abstract: The sampling uncertainty for pesticide residues in carrots, parsley leaves and selected medium size crops was estimated with simple random sampling by applying range statistics. The primary samples taken from treated fields consisted of individual carrots or a handful of parsley leaves. The samples were analysed with QUEChERs extraction method and LCMS/MS detection with practical LOQ of 0.001 mg/kg. The results indicate that the average sampling uncertainties estimated with simple random sampling and range statistics were practically the same. The confidence interval for the estimated sampling uncertainty decreased with the number of replicate samples taken from one lot and the number of lots sampled. The estimated relative ranges of sampling uncertainty are independent from the relative standard deviation of the primary samples. Consequently the conclusions drawn from these experiments are generally applicable. There is no optimum for sample size and number of lots to be tested for estimation of sampling uncertainty. Taking a minimum of 6 replicate samples from at least 8-12 lots is recommended to obtain a relative 95% range of sampling uncertainty within 50%. The cost of sampling/analyses, the consequences of wrong decision should also be taken into account when a sampling plan is prepared.
authors.affiliation: a National Food Chain Safety Office , Directorate for Food Safety Risk Assessment , Budapest , Hungary.
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Farkas
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Horváth
authors.forename: Kata
authors.initials: K
authors.lastname: Kerekes
authors.forename: Árpád
authors.initials: Á
authors.lastname: Ambrus
authors.forename: András
authors.initials: A
authors.lastname: Hámos
authors.forename: Mária Szeitzné
authors.initials: MS
authors.lastname: Szabó
mesh_terms: D002853:Chromatography, Liquid; D018556:Crops, Agricultural / Q000737:chemistry*; D018552:Daucus carota / Q000378:metabolism*; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data; D005506:Food Contamination / Q000032:analysis*; D006540:Herbicides / Q000032:analysis*; D006814:Hungary; D057230:Limit of Detection; D010573:Pesticide Residues / Q000032:analysis*; D028528:Petroselinum / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D015983:Selection Bias; D053719:Tandem Mass Spectrometry; D035501:Uncertainty
chemical_list: D006540:Herbicides; D010573:Pesticide Residues