Liquid chromatographic determination of XXXX insecticides and metabolites in crops. I. Collaborative study.

@entity9159 @entity1042 @entity1626 @entity415 @entity2961 @entity38 @entity56487
A liquid chromatographic (LC) multiresidue method for determining residues of @entity56487 insecticides in crops was collaboratively studied in 6 laboratories. @entity1042 and a mechanical ultrasonic homogenizer are used to extract the @entity9159 . Water-soluble plant coextractives and nonpolar plant lipid materials are removed from the @entity2961 residues by liquid-liquid partitioning. Additional crop coextractives (e.g., carotenes, @entity38 ) are removed with a Nuchar SN-silanized Celite column. The @entity2961 residues are then separated on a reverse phase LC column, using an @entity1626 -water gradient mobile phase. Eluted residues are detected by an in-line post-column fluorometric detection technique. Seven @entity9159 and 2 @entity2961 metabolites were included in the collaborative study. Each collaborator determined all the @entity9159 at 2 levels (approximately 0.05 ppm and United States tolerance) in blind duplicate samples of grapes and @entity415 . Fortified and control samples were analyzed. Repeatability coefficients of variation for all the @entity9159 on the 2 crops averaged 4.7% and ranged from 2.4 to 7.1%. Reproducibility coefficients of variation for all the @entity9159 on the 2 crops averaged 8.7% and ranged from 5.3 to 12.4%. Accuracy, measured by comparison with fortification values, averaged 95% and ranged from 79 to 103%. The estimated limit of quantitation is 0.01 ppm. The method has been adopted official first action.
