Spectrophotometric determination of metribuzin herbicide with p-dimethylamino-benzaldehyde using factorial designs for optimization of experimental variables

A new simple spectrophotometric method has been developed for the determination of metribuzin herbicide in formulations and potato samples. The method is based on the reaction of p-dimethylamino-benzaldehyde (DMAB) with sodium hydroxide via Cannizzaro's reaction at 100 °C to form a p-dimethylaminobenzoic acid. The resultant p-dimethylaminobenzoic acid reacted with metribuzin herbicide in acidic media at 100 °C and the yellow colored product was measured at 455 nm. The reaction conditions and other analytical parameters were studied and optimized. A linear plot between absorbance and concentration over the range from 0.2 to 20 μg mL−1 was found with molar absorptivity of 2.1 × 104 L mol−1 cm−1. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.05 and 0.2 μg mL−1, respectively. The proposed method has been successfully applied for the analysis of commercial formulation and potato sample. The recoveries of the method were found to be in the range from 92.16 ± 0.06% to 96.66 ± 0.18%.Two level factorial designs of 23 and 22 were used to optimize all parameters, determine the influence of different parameters and their interactions on the final product formation.