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. © 2013