Effects of fruit acidity and storage conditions on the rate of degradation of azinphos methyl on apples and lemons

Degradation of azinphos methyl during storage of apples and lemons in refrigerated rooms was studied. The pesticide was applied to the trees according to the recommended application procedures in Greece. Apples and lemons received a single application with azinphos methyl at a rate of 60 g of active igredient/100 l. Residues were determined with a simple gas-chromatographic method; the recovery of azinphos methyl from apples was found to be 87-123% and from lemons 81-105% and the limit of determination was 0.002 mg/kg. Half-lives of azinphos methyl degradation were 10 and 5 days for apples and lemons from the trees, respectively. During storage of the fruits in refrigerated rooms, half-lives of the insecticide were to 122 and 46 days, respectively. The high rate of degradation of azinphos methyl residues in lemons compared to that in apples was largely attributed to the high lemons acidity. Fruit juice was produced from both apples and lemons. Azinphos methyl residues were detected in apple juice but not in lemon juice.