A facile method for in-situ detection of thiabendazole residues in fruit and vegetable peels using Surface-Enhanced Raman Spectroscopy

A flexible Surface-Enhanced Raman Spectroscopy (SERS) substrate based on silver nanoparticles encapsulated in an agar gel has been probed to detect the fungicide thiabendazole (TBZ) reaching a limit of detection (LOD) of 30 ng/cm2. In addition, a simple and sensitive strategy was employed for in-situ detection of TBZ on fruit and vegetable peels. For that purpose, peels of different fruits and vegetables were intentionally contaminated with different amount of TBZ, and the analyte was subsequently extracted within few seconds by gently rubbing the surface with the SERS substrate. The lowest value of TBZ detected on eggplant and green pepper peels was 50 ng/cm2. The values achieved for apple and pear peels were 0.20 μg/cm2 and 40 ng/cm2, respectively. On the other hand, for tomato and strawberry peels the lowest value achieved was 0.50 μg/cm2. The variation in sensitivity can be attributed to differences in the surface properties of the different peels. The above results show that this flexible SERS substrate can be further employed for the detection of contaminants in practical applications for food safety inspection.