Selective detection of fenaminosulf via a molecularly imprinted fluorescence switch and silver nano-film amplification

A novel fluorescence switch sensor was constructed for detecting the fungicide fenaminosulf (FM), based on a dye-doped molecularly imprinted polymer (MIP) and silver nanofilm amplification. The MIP was prepared by electropolymerization of hydroquinone doped with neutral red on the silver nanofilm modified electrode. A fluorescence signal was produced by the neutral red and the fluorescence intensity was diminished by the ion pair that formed via electrostatic forces between FM and the dye. Therefore, elution and adsorption of FM by the MIP acted as a switch to control the fluorescence intensity, which was effectively amplified by the silver nanofilm. The decrease in fluorescence intensity was linear with the FM concentration, establishing a new method for FM detection. Under optimal conditions, good linear correlation was obtained for FM concentrations over the range from 2.0×10−10 to 4.0×10−8 mol/L, with a detection limit of 1.6×10−11 mol/L. This method was utilized to determine residual FM in vegetable samples, and recoveries ranging from 92.0% to 110% were obtained.