title: Validation of methods used in the Florida Department of Agricultural and Consumer Services' Chemical Residue Laboratory.
abstract: Very few methods for detecting residues of pesticides in food or agricultural samples have undergone rigorous colloborative study and possess official AOAC status. The Chemical Residue Laboratory has formalized a method validation scheme to use when incorporating or developing new, unofficial methods. These methods are validated by assessing certain performance parameters: scope, specificity, linear range, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). For accuracy and precision assessment, 12 replicate fortifications must yield recoveries within the range of 70-120% with a coefficient of variation (CV) that compares favorably to the Horwitz CV. LOD and LOQ are equivalent to 3 and 10 times, respectively, the background signal contributed by a sample matrix blank. This criterion that we use for LOD/LOQ is not universal. In fact, because of differing definitions, we have encountered difficulties in enforcing a tolerance by using a registrant's method. This paper also presents an example of our method validation scheme, using a recent method development project for detecting sulfamethazine in raw milk. The sulfamethazine project also revealed unanticipated personnel problems, underscoring the importance of the human factor in quality assurance.
authors.affiliation: Florida Department of Agriculture and Consumer Services, Chemical Residue Laboratory, Tallahassee 32399-1650.
authors.forename: G A
authors.initials: GA
authors.lastname: Parker
mesh_terms: D000383:Agriculture; D000818:Animals; D003257:Consumer Product Safety; D005431:Florida; D005504:Food Analysis / Q000379:methods*; D007753:Laboratories / Q000592:standards*; D008892:Milk / Q000032:analysis; D010573:Pesticide Residues / Q000032:analysis*; D015203:Reproducibility of Results; D013219:State Government; D013418:Sulfamethazine / Q000032:analysis
chemical_list: D010573:Pesticide Residues; D013418:Sulfamethazine