The Detection of Cypermethrin on the Surface of Apple by IR Micro-Imaging

Abstract

IR micro-imaging technology is a new kind of analytical technology, which combines direct-visualizing image and infrared spectroscopy analysis. Each pixel in the IR micro-image is a whole IR spectrum, therefore, IR micro-image contains not only the information of spatial distribution but also the information of spectrum with hundreds of wavelength points. In this study, the feasibility of using IR micro-imaging to detect cypermethrin on the surface of apple skin was discussed, both cypermethrin single substance powder and the apple skin that was sprayed with cypermethrin single substance solution were used as research objects, IR micro-image and infrared spectrum were all analyzed. The results showed that IR micro-image of cypermethrin single substance powder could effectively reflect the information of spatial distribution, and the characteristic peak corresponding to molecular structure of cypermethrin could also be observed in the IR spectrum which extracted from IR micro-image of cypermethrin single substance powder. In the infrared spectrum of the apple skin that sprayed with cypermethrin single substance solution, four characteristic absorption peaks corresponding to cypermethrin which were located at 1591 cm-1, 1489 cm-1 , 1290 cm-1and 801 cm-1 were observed, which confirmed that there was cypermethrin existed on the apple skin. The present study indicated that the detection of cypermethrin on the surface of apply by IR micro-imaging technology was feasible, which provided a good foundation for the detection of fruit and vegetable pesticide residues by IR micro-imaging technology.