A rapid spectrophotometric determination of imidacloprid in selected commercial formulations in the presence of 6-chloronicotinic acid

A simple first-order derivative spectrophotometric method was deve- loped for the simultaneous determination of imidacloprid and 6-chloronicotinic acid (6-CNA). By using the zero-crossing approach, imidacloprid was deter- mined at 249 nm and 6-CNA at 236 nm with detection limits of 0.32 and 0.17 µg mL -1 , respectively, and relative standard deviations not exceeding 1.2 % in the case of model systems. The proposed method was applied for the deter- mination of imidacloprid and 6-CNA in commercial formulations. A conven- tional spectrophotometric method (at 270 nm) was also employed for the deter- mination of the content of imidacloprid in the same commercial formulations. The results of the developed spectrophotometric methods were in good agre- ement with those obtained by the high-performance liquid chromatographic