Effects of storage conditions and fruit processing on the degradation of parathion methyl on apples and lemons.

Degradation of parathion methyl on lemon and apple on the trees, during storage of these fruits in refrigerated rooms, and during juice production was studied. The pesticide was applied to the trees according to the recommended application procedures. Apples and lemons received a single application of parathion methyl at 40 g active ingredient/100 litres. Residues were determined with a simple gas-chromatographic method; the recovery rate of parathion methyl from apples and lemons was 85-108% and the limit of determination was 0.004 mg kg(-1). The half-lives of parathion methyl on the trees were 7 days for apples and 5 days for lemons. The duration of storage of the fruits in a refrigerated room have been largely extended to 65 and 63 days, respectively. The high acidity of lemons was found not to affect the degradation rate of parathion methyl. When fruit juice was produced from both apples and lemons, parathion methyl residues were detected in apple but not in lemon juice.