Quantification of β-Cyfluthrin Residues on Field-Grown Kale and Collards Greens

Pyrethroids such as β-cyfluthrin are synthetic analogues of the natural pyrethrins that are extracted from the flower of Pyrethrums (<i>Chrysanthemum cinerariaefolium</i> and <i>C. c</i><i>occ</i><i>ineum</i>). β-cyfluthrin is a commonly used insecticide on brassica leaves to control insects attack such as Lepidoptera, Coleoptera, Hemiptera, and Diptera families for better crop yield and quality. A field study was conducted to investigate the dissipation pattern of β-cyfluthrin on collard and kale leaves following spraying of the commercial formulation Baythroid® XL. The objectives of the study were to determine the dissipation constants and half-life (T½) values of β-cyfluthrin on kale and collard grown under field conditions and to determine the workers' re-entry time following β-cyfluthrin spraying for workers and consumer safety. Following spraying, residues of β-cyfluthrin were extracted from the leaves using ethyl acetate and cleaned up through an open glass chromatographic column packed with Florisil. Quantification and confirmation of the insecticide residues were carried out using a gas chromatograph (GC) equipped with an electron capture detector (GC/ECD) and a GC equipped with a mass selective detector (GC/MSD), respectively. The method successfully separated the 4 isomers of β-cyfluthrin, revealing the molecular ion fragments at m/z of 127, 163, 206, and 226, respectively. Following spraying, the initial residues (sum of isomers) of β-cyfluthrin were lower on collard (9.5 µg g<sup>-1</sup>) than on kale leaves (28.8 µg g<sup>-1</sup> fresh leaves). The study revealed a greater T<sub>1/2</sub> value of 8.2 days of β-cyfluthrin on collard than on kale leaves (5.1 days).