New SERS Imaging Technique Unveils Ultra-Sensitive Detection of Pesticide Residues in Crops

Agricultural crops are consistently treated with pesticides to prevent the crops from being ruined by pests. However, the unfortunate reality is that many of these crops still contain pesticide residues after they are harvested. As a result, detection techniques are needed to ensure the food being marketed to consumers is free of these residues.

Surface-enhanced Raman spectroscopy (SERS) is one technique that has been used for this purpose. Numerous studies have showcased how SERS can be used effectively as a quality control mechanism for ensuring food safety (1–3). SERS can detect molecules at low concentrations and allows for high sensitivity and specificity (2,3). In a recent study published in the Journal of Hazardous Materials, researchers from Harbin Medical University (Heilongjiang, China) have introduced a method for detecting pesticide residues in crops that uses SERS imaging (1). The researchers show that SERS imaging is more comprehensive and less invasive in monitoring pesticide residues compared to traditional methods (1).

Spraying pesticide onto potato plants outdoors on sunny day | Image Credit: © New Africa - stock.adobe.com.

Monitoring pesticide residues in crops is critical for ensuring food safety and protecting the environment, but current methods have significant limitations (1–3). Traditional pesticide detection techniques are often invasive, labor-intensive, and unable to provide real-time monitoring (1). Additionally, they can struggle with interference from endogenous compounds found in the peel and pulp tissues of fruits and vegetables, resulting in reduced sensitivity and accuracy (1).

In their study, the research team used borohydride-reduced nanoparticles to create a stable and sensitive SERS assay. This assay the research team created allowed for the detection of pesticide residues at levels below 1 picogram per milliliter (pg/mL) (1). This new method also included a robust quantitative analytical capability, providing detailed insights into the concentration and distribution of pesticides within crops (1).

The new method also integrated SERS imaging with pesticide residue detection. By doing so, the researchers were able to map the distribution of pesticide residues present on the exterior of various vegetables and fruits (1). The research team was also able to use SERS imaging to see the interior of these food products, allowing them to see where pesticide residue was on the inside of the fruit and vegetables (1). The team also sought to prevent interference caused by plant autofluorescence. To do so, they used vertex component analysis (VCA), which improved accuracy and allowed for better identification of pesticide residues (1).

In the study, two commonly used pesticides were evaluated by the detection model: dimethoate (DIM), an organophosphorus-based pesticide, and cypermethrin (CYP), a pyrethroid-based pesticide. As DIM and CYP are two of the most common pesticides used in agricultural pest control, the researchers wanted to test these two pesticides against their model (1). By using SERS imaging, the researchers were able to monitor the residues of these pesticides across various stages of crop development, confirming the method’s precision and sensitivity (1).

This new SERS-based detection strategy offers significant potential for improving food safety by enabling more comprehensive monitoring of pesticide residues in crops. Its ultra-sensitive detection capabilities make it possible to identify even the smallest traces of hazardous substances, ensuring that food products are safer for consumers (1).

Food safety applications could benefit from this SERS detection model. By providing farmers with a more precise way to monitor pesticide use, the technique could help reduce the overall amount of pesticides applied to crops (1). The hope is that by using SERS detection methods, farmers can reduce environmental contamination in their food products that go to market.

References

1. Sun, X.; Zhao, Y.; Liu, L.; et al. Visual Whole-process Monitoring of Pesticide Residues: An Environmental Perspective Using Surface-enhanced Raman Spectroscopy with Dynamic borohydride-reduced silver nanoparticles. J. Hazard. Mater. 2024, 465, 133338. DOI: 10.1016/j.jhazmat.2023.133338
2. Wetzel, W. New Raman Spectroscopy Techniques Promise Safer Produce. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/new-raman-spectroscopy-techniques-promise-safer-produce (accessed 2024-10-24).
3. Wetzel, W. New Method for Rapid SERS Detection of Pesticides in Agricultural Products Unveiled. Spectroscopy. Available at: https://www.spectroscopyonline.com/view/new-method-for-rapid-sers-detection-of-pesticides-in-agricultural-products-unveiled (accessed 2024-10-24).