Ultrasensitive and quantitative detection of paraquat on fruits skins via surface-enhanced Raman spectroscopy

In our study, we introduced a rapid, low-cost and nondestructive ‘surface spray’ method to achieve the quantitative detection of the pesticide residues on fruits skins. Taking advantage of the high enhancement ability of the surface-enhanced Raman spectroscopy (SERS) of the optimized Ag nanoparticles colloid, the limit of detection (LOD) of paraquat (PQ) on the peels of pears and apples could reach the order of magnitude of 10−9 M, much lower than the maximum residue limit of 0.05 mg/kg (∼10−4 M) in a large number of countries including the USA and China. The quantitative detection of PQ was achieved as well. This opens a new avenue for advancing the applications of SERS technique in the fields of food safety, drug security, and environment monitoring.