A New Spectrophotometric Method for the Determination of Imidacloprid in Real Samples by Diazotization-Coupling Reaction

In this study, a novel azo dye with unique sensing properties, named IMID-P, was synthesized and comprehensively characterized. The synthesis involved the diazotization of the widely used insecticide Imidacloprid, followed by a coupling reaction with 5-amino-2-hydroxybenzoic acid in an alkaline medium (pH ~11.3), yielding a stable yellow azo compound. The dye exhibited a maximum absorbance (λmax) at 414.5 nm. Its successful synthesis and structural confirmation were achieved through ultraviolet–visible (UV-vis) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (¹H-NMR), and carbon nuclear magnetic resonance (¹³C-NMR) spectroscopy. IMID-P demonstrated remarkable sensitivity, as evidenced by its low limit of detection (LOD), and showed excellent linearity, adhering to the Beer-Lambert law within a concentration range of 5–60 μg/mL. Furthermore, the binding mechanism between Imidacloprid and 5-amino-2-hydroxybenzoic acid was investigated, providing insights into the dye’s formation. These findings emphasize IMID-P's potential for quantifying Imidacloprid in environmental samples like water and soil, and its applicability in commercial insecticides formulations.