Spectrophotometric Method for Quantification of Fenoxaprop-p-ethyl Herbicide in Commercial Formulations and Agricultural Samples

Abstract

A simple spectrophotometric method was developed for determination of fenoxaprop-p-ethyl herbicide in agricultural samples. The method is based on the acid hydrolysis of fenoxaprop-p-ethyl to form 6-chloro-2,3-dihydrobenzoxazol-2-one (CDHB) and ethyl 2-(4-hydroxyphenoxy) propionate (EHPP). The 6-chloro-2,3- dihydrobenzoxazol-2-one was used as a coupling reagent in diazotization reaction. The absorbance of the azo dye was measured at 430 nm. The reaction conditions were optimized for hydrolysis as well as for the diazotization reaction. The Beer's law was obeyed over the concentration range of 0.2-25 µg mL⁻¹with molar absorptivity of 1.4 x 10⁴ L mol⁻¹ cm⁻¹. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.029 and 0.098 µg mL⁻¹, respectively. The method has been successfully applied to the determination of fenoxaprop-p-ethyl I commercial formulations and various agricultural samples. The % recoveries were found in the range of 95-97%.