Evaluation of endosulfan residues in vegetables grown in greenhouses

The reduction in residue levels of endosulfan with time after treatment of tomatoes, green beans, peppers and cucumbers grown in different types of co mmercial greenhouses (flat- and asymmetric-roof greenhouses) in Almeria (Sp ain) was investigated. A study of the major and minor degradation products of endosulfan in peppers and encumbers (endosulfan-sulfate, -ether and -lac tone) was carried out using gas chromatography-tandem mass spectrometry (GC -MS/MS). To establish the influence of environmental conditions on the degr adation of endosulfan, several field trials have been carried out in which crops were sprayed at different rates (full, half- and quarter- of those ra tes recommended) during two seasons (spring and winter). For statistical pu rposes, the disappearance of endosulfan with time was considered to follow a pseudo-first-order reaction. Analysis of variance (ANOVA) has been applie d to the results obtained. Half-lives of residue disappearance were 4.03-4. 68 days in green beans, 4.03-4.20 days in tomatoes, 8.22 days in peppers an d 7.97 days in cucumbers. Half-lives in spring were shorter than in the win ter season. The application rate and the type of greenhouse did not influen ce the half-lives. (C) 2001 Society of Chemical Industry.