To estimate variations in pesticide residue levels in crops, the variability factors (VFs, the 97.5th percentile of the residue levels in the sample divided by the average residue levels in the lot) in residue levels of acetamiprid and cypermethrin applied to cabbage and grapes were investigated, respectively. The VFs in the residue levels of both pesticides in cabbage (2.00 and 2.39, respectively) were clearly higher than those in grapes (1.82 and 1.63, respectively). Although the residue levels of both pesticides in grapes showed a normal distribution, those values in cabbage were slightly skewed at lower residue levels. Individual residue levels in grapes had a good agreement between acetamiprid and cypermethrin. In contrast, the distribution of cypermethrin residue levels in cabbage was slightly skewed at higher residue levels as compared to that of acetamiprid. These results indicate that the difference in the relative distribution of the two pesticides between cabbage and grapes might be due to the influence of various factors such as differences in crop species, plant cultivation methods, and physicochemical properties of the pesticides.

A direct competitive enzyme-linked immunosorbent assay (dc-ELISA) for the analysis of emamectin residues in agricultural products was developed using a prepared mouse monoclonal antibody. The working range was 0.3-3.0 ng/mL, and the 50% inhibition concentration (IC(50)) was 1.0 ng/mL. The assay was sufficiently sensitive for analysis of the maximum residue limits in agricultural products in Japan (>0.1 microg/g). Emamectin residues contain the following metabolites: the 4''-epi-amino analogue, the 4''-epi-(N-formyl)amino analogue, the 4''-epi-(N-formyl-N-methyl)amino analogue, and the 8,9-Z isomer. The dc-ELISA reacted with these compounds at ratios of 113, 55, 38, and 9.1% of the IC(50) value of emamectin benzoate. Seven kinds of vegetables were spiked with emamectin benzoate at concentrations of 15-300 ng/g, and the recoveries were 91-117% in the dc-ELISA. The dc-ELISA results agreed reasonably well with results obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using spiked samples and actual (incurred) samples. The results indicate that the dc-ELISA was useful for the analysis of emamectin benzoate residues in agricultural products.

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.

The effects of water-soaking pre-treatment of powdered dry cereal on pesticide residue analysis in brown rice and wheat were examined. The recovery of several pesticide residues found in cereal by acetone extraction without water-soaking was as low as 6ϳ68% of recovery after watersoaking pre-treatment for 30 min. The optimal soaking time in water was 15 to 30 min for the powdered cereal samples. The relative recovery of spiked pesticides and residual pesticides was not always parallel between the two extraction conditions, i.e., acetone extraction with and without water-soaking pre-treatment. Pre-treatment produced higher measured values in many cases, but also resulted in lower values for some pesticides like malathion and diazinon. Soaking dry samples in water for 15ϳ30 min as pre-treatment will give good residual pesticide extraction.