Development of a Fluorometric Method for Carbaryl Determination Using MCM‐41 Containing Cetyltrimethylammonium

This study investigated a solid base reagent for the fluorometric determination of carbaryl residues in vegetables. The method is based on the reaction between carbaryl and Mobil Composition of Matter No. 41 (MCM‐41) containing cetyltrimethylammonium (CTA), denoted as MCM‐41‐CTA, which produces 1‐naphthol. The generated 1‐naphthol exhibited a strong fluorescence signal at 485 nm when excited at 335 nm, enabling fluorometric detection. MCM‐41‐CTA was synthesized using tetraethoxysilane as the silica source and cetyltrimethylammonium bromide (CTAB) as the template. Mesoporous structure, surface basicity, and functional groups of MCM‐41‐CTA were analyzed. The hydrolysis reaction between carbaryl and MCM‐41‐CTA was optimized with the best results achieved using 100 mg of MCM‐41‐CTA in a carbaryl solution containing 50% ethanol, with a reaction time of 60 min. Under these conditions, the developed method showed a linear response for carbaryl concentration from 0.12 to 10 μM, with a detection limit of 0.11 μM. The method was successfully applied to the analysis of real samples, quantifying carbaryl residues in chili and Thai eggplant. Validation against ultra‐high‐performance liquid chromatography (UHPLC) showed strong agreement between the two techniques. Furthermore, an interference study confirmed that the presence of the tested species had negligible effects on the fluorescence signal of 1‐naphthol. The findings suggest that the developed method is a promising tool for efficiently and accurately detecting carbaryl residues in agricultural products.