DETERMINATION OF DINITROANILINE HERBICIDE IN FOOD SAMPLES AND COMMERCIAL FORMULATIONS USING SPECTROPHOTOMETRIC METHOD

A simple spectrophotometric method for the determination of herbicides residues of dinitroaniline (trifluralin and pendimethalin) in food samples is described. The proposed method is based on the base hydrolysis of dinitroaniline herbicide with sodium hydroxide. The active ingredient was converted to 2,4 dinitroaniline. Hydrolyzed product was converted to diazonium salt by using sodium nitrite in acidic media. The diazonium salt on coupling with aniline gave red colored azo dye. The absorbance of the azo dye was measured at 460 nm. The reaction conditions were optimized for hydrolysis as well as for the diazotization reactions. The method shows a linear range between 0.5 - 40 μg mL^-1 with molar absorpitivity of 1.53 ×10^4 L mol^-1 cm^-1. The limit of detection and limit of quantification were calculated and found to be 0.21 μg mL^-1 and 0.71 μg mL-1 respectively and Percent recovery was in the range of 86.2 - 92.7%. The method is sensitive, simple and suitable in routine laboratories for application to environmental samples and formulation. The method was successfully applied to soil, water and vegetable (cabbage, potato, onion and garlic samples) collected from crop fields of Peshawar and Swat.