現代の化学と応用

概要

Investigation of Rate of Photo Degradation of Chlorothalonil, Lambda Cyhalothrin, Pentachlorophenol and Chlropysis on Tomato and Spinach

Mbugua JK, Mbui D and Kamau GN

Photo-degradation of common pesticides and herbicides on the surface of tomato fruit and spinach leaves were studied. Samples were spiked with 100 mg/ml of lambda cyhalothrin, chlorothalonil, chlorpyriphos and pentachlorophenol standard solutions in acetone. Thy were air dried for 1 minute and exposed to light of various intensities; sunlight, 40 w, 60 w, 75 w and 100 w bulbs after spreading on the surface of spinach and tomatoes for 15, 30, 45 and 60 minutes and then washed in acetone. The pesticide concentration in the samples was analyzed with a UV Visible spectrophotometer. The rate of degradation of chlorothalonil, lambda cyhalothrin, pentachlorophenol and chlorpyriphos was also calculated and rate constants obtained for each residue. The results obtained indicated that the 100 W bulb degradation ranged from 20-95% for all the molecules in both tomato fruit and spinach leave surface. The residues breakdown followed a 1st order kinetics.