Investigating the Effects of Formulation, and Geographical Location on Degradation of Carbendazim in French Beans, Kenya

Abstract

This study was conducted in Naivasha and Kabaa regions of Kenya during short and long rain seasons to determine the effects of difference in formulation and geographical location on the degradation and pre-harvest interval of carbendazim pesticide in French beans. Pre-harvest interval (PHI) ensures food safety after application of pesticide. Serengeti French beans variety; Chariot 500 SC and Rodazim SC carbendazim formulation were used. The pesticide was applied at the rate of 625g of carbendazim per hectare before harvest and the French beans samples were collected on 0, 3, 7, 14 and 16 days after pesticides applications, analysed using liquid chromatography technique with a triple quadruple mass detector (LCMSMS). Carbendazim degradation in the first three days after the pesticide application was sharp regardless of the formulation used, season or geographical location. The percentage degradation of carbendazim showed insignificant variation regardless of the initial concentration. There was more than 96.7% reduction of carbendazim residues on the 14th day after pesticides applications. Two-way ANNOVA was used to compare the breakdown of carbendazim based on its formulation and geographical locations. The F-critical values (F) obtained were 0.02 Ë‚ 4.14 and 0.17 Ë‚ 2.9 for formulation and geographical locations respectively at 95% confidence level. The results show that there is no statistical significance difference in breakdown of carbendazim in French beans within the formulations and geographical locations. The half-life of carbendazim was calculated using Langmuir-Hinshelwood kinetic model equation. The results obtained indicate that carbendazim had a dissipation half-life of 1.7 days and 5 day pre-harvest interval calculated at 50% of the 200µg/kg.