Cypermethrin residues in apples were evaluated to consider individual variations from sample-to-sample, eld-toeld, and edible-to-inedible portions. e VF (variability factor) values obtained from the 97.5th percentile and the mean pesticide residue levels of 130 individual apple samples were 1.76 and 1.75, respectively, and the highest residue level was approximately 10 times the lowest one. e results suggest that, in order to obtain reliable values of pesticide residue levels, a su cient number of samples is essential. Regarding eld-to-eld variability, the highest mean residue level from 8 orchards was approximately 2.3 times that of the lowest. e pesticide residue level determined for an entire fruit was slightly higher than that for the edible portions, and there was no signi cant statistical di erence between the two.
To estimate the influence of sample processing with a blender, we conducted a homogeneity test using a bulk sample of preharvest grapes. Relative standard deviations (RSDs) were calculated from the concentrations of pesticides in the portions from the top, middle, and bottom of the homogenate with fine and rough particles. The results from adequate sample processing showed that the RSDs of the residue levels of all five pesticides in the fine-particle homogenate were lower than 10%. In contrast, the results under problematic conditions such as short blending times and long standing times after blending showed higher RSDs (>15%). The RSDs of nonpolar pesticides showed greater variabilities under the problematic conditions than those of polar pesticides. Separate analyses of the precipitate and supernatant phases suggested that the distribution bias of skin particles in the homogenate has a major effect on the concentration of nonpolar pesticides because of weighing errors in the extracted portions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.