Abstract:Surface-enhanced Raman spectroscopy (SERS) combined with the fast solvent pretreatment method was used to rapidly detect difenoconazole residues in celery. Celery juice was extracted with acetonitrile, then N-propylethylenediamine, C18, and graphitic carbon were used to remove fluorescent materials in celery juice, such as fatty acids, waxes, pigments, cholesterols. SERS signals corresponding to different concentrations of difenoconazole solutions in celery juice matrix were recorded using a laser Raman spectrometer. The results showed that the intensity of the characteristic peak at 1192 cm-1 and the concentration of difenoconazole between 1 and 10 mg/L in celery juice matrix exhibited a good linear relationship, with a correlation coefficient of 0.9622. The limit of detection by SERS for difenoconazole in celery juice matrix was 1 mg/L and the recovery of the method was in the range of 92.4% to 113.2%. Additionally, the relative standard deviation (RSD) was between 8.83% and 12.4%. t-Tests were performed on four samples with unknown concentrations and the results indicated that there were no significant difference between the reference and predicted values. The operation of this method is simple and the duration for the detection of a single sample was only 20 minutes. Therefore, this method meets the national requirement for the maximum residue limits (MRLs) of difenoconazole in vegetables and the results of this study will help in the development of devices to rapidly detect pesticide residues in vegetables.
