Quantitative Detection of Isofenphos-Methyl in Corns Using Surface-Enhanced Raman Spectroscopy (SERS) with Chemometric Methods

Residual pesticides in agricultural production are one of the major food safety concerns around the world. In this study, we investigated the amount of isofenphos-methyl in corns by using surface-enhanced Raman spectroscopy (SERS) coupled with chemometric methods. The highest isofenphos-methyl peak at 1043 cm(-1) was used to detect and quantify the amount of isofenphos-methyl spiked in methanol-water (1:1) solvent and corns. The limits of detection (LODs) of isofenphos-methyl in methanol-water solvent and corns were 0.01 mu g/mL and 0.01 mu g/g, respectively. Quantitative detection of isofenphos-methyl residues (0-5 mu g/mL) was conducted using partial least squares (PLS) model. Based upon the results of leave-one-out cross-validation, isofenphos-methyl could be predicted by PLS (the correlation coefficient was 0.9964) with a low root mean square error of calibration (RMSEC=0.146). The developed SERS method provides a much simpler and more sensitive way to monitor isofenphos-methyl for safe production of corns, which can be extended to the other agricultural products.