A gas chromatographic method for the determination of the fungicide chlorothalonil in tomatoes and cucumbers and its application to dissipation studies in experimental greenhouses

Journal of the Brazilian Chemical Society

Kurz, Márcia H. S.¹  Zanella, Renato¹  Primel, Ednei G.¹  Costa, Ivan F. D. da¹  Fundação Universidade Federal do Rio Grande, Rio Grande, Brazil¹  Gonçalves, Fábio F.¹  Adaime, Martha B.¹  Universidade Federal de Santa Maria, Santa Maria, Brazil¹ 

关键词: chlorothalonil;    tomatoes;    dissipation;    cucumbers;    GC-ECD;   

DOI  :  10.1590/S0103-50532008000600012

学科分类：化学（综合）

来源: SciELO

【 摘 要 】

A new method to evaluate the levels of residue and the dissipation of chlorothalonil fungicide in tomatoes and cucumbers grown in experimental greenhouses was developed and validated. The vegetables were submitted to a single spraying with chlorothalonil at half, equal to and double of the recommended dose. Chlorothalonil residues were extracted in Ultra-Turrax system using ethyl acetate in the presence of anhydrous sodium sulphate and determined by gas chromatography with electron capture detection. The analytical curves were linear from 0.005 to 5.0 mg L-1, with coefficient of determination higher then 0.995. The assays provide acceptable results with RSD values below 10.5% and recoveries were between 92.2 and 114.5% for tomatoes, and between 86.2 and 103.3% for cucumbers, both obtained from spiked samples at 0.028, 0.28, 2.8 and 5.0 mg kg-1 levels. Statistical interpretation of residue levels fitted to a first-order model for the dissipation behavior of chlorothalonil. The mean half-life after treatments at the recommended dose, in the two experimental years, was 8.8 days for tomatoes and 1.6 days for cucumbers. The higher decrease rate of chlorothalonil residues in cucumbers is mainly due to the higher growth rate of this vegetable relative to tomato. The developed method has proven to be efficient for the determination of chlorothalonil residues in tomatoes and cucumbers with a limit of quantification of 0.02 mg kg-1 level, permitting to evaluate the risk of consumer exposure to these residues.

【 授权许可】

Unknown