A novel and visible ratiometric fluorescence determination of carbaryl based on red emissive carbon dots by a solvent-free method

In this study, a simple and effective ratiometric fluorescence method has been developed for carbaryl detection, utilizing red emissive carbon dots (R-CDs). The underlying principle of this proposed strategy relies on the rapid hydrolysis of carbaryl under an alkaline condition and production of 1-naphthol with blue-emission at 462 nm. Furthermore, the as-synthesized R-CDs (Em. 677 nm), serve as a reference, enhancing the visual tracking of carbaryl through the transformation of fluorescent color from red to blue. The concentration of carbaryl exhibits a commendable linear correlation with the ratio of fluorescence intensity, ranging from 0 to 20 μg/mL (R2 = 0.9989) with a low detection limit of 0.52 ng/mL. Additionally, the described methodology can be used for the enzyme-free visual assay of carbaryl, even in the presence of other carbamate pesticides and metal ions, in tap water and lake water samples with excellent accuracy (spiked recoveries, 94%–106.1%), high precision (relative standard deviation (RSD) ≤ 2.42), and remarkable selectivity. This fast and highly sensitive naked-eye ratiometric sensor holds immense promise for carbaryl detection in intricate environments and food safety fields.