Rapid detection of nitenpyram in fruits using molecularly imprinted polymers coupled with SERS technology

In this study, the novel method combining molecularly imprinted polymers and surface-enhanced Raman spectroscopy for selectively extracting and detecting nitenpyram in fruits was proposed. The molecular imprinted polymers were prepared by precipitation polymerization method. The obtained imprinted polymers presented uniform spherical particles, and the average diameter (about 2 mu m) was obviously larger than non-imprinted polymers. Dynamic and static adsorption experiments validated that imprinted polymers possessed fast adsorption rate (only 10 min), large adsorption capacity (5187.06 mu g/g) and good specific recognition ability towards nitenpyram. Under optimum solid phase extraction conditions (80 mg dosage, pH at 5, H2O as sample solvent, 5 % methanol-H2O as washing solvent, 2 mL 10 % formic acid-ethyl acetate as elution solvent), the molecularly imprinted polymers coupled surface-enhanced Raman spectroscopy method showed good linear relationship (1-25 mu g/g) with R-2 > 0.9736. The lower limits of detection (0.14-0.74 mu g/g) in different fruits (pear, peach, apple, tomato) were achieved. The satisfactory spiked recovery (71.3-103.89 %) was also obtained. This study provided a rapid, sensitive, specific and practical method for analyzing nitenpyram based on synergistic effect of specific recognition of imprinted polymers and high sensitivity of surface-enhanced Raman spectroscopy. More importantly, it presented useful strategy for removing interference for SERS system, promoting SERS into actual application for rapid detection of trace pesticide in foods.