Trace Detection of Thiabendazole on Bananas

Importance of the Topic

Thiabendazole (TBZ) is a widely applied fungicide and antiparasitic agent in agriculture and animal feed. Ensuring its residues on fruits like bananas remain within safe limits is critical to consumer health and regulatory compliance. Rapid, sensitive screening tools facilitate on-site monitoring, reduce laboratory dependence, and support risk management in the food supply chain.

Purpose and Overview of the Study

This application note demonstrates the use of the Metrohm Instant SERS Analyzer (MISA) for trace-level detection of TBZ residues on banana peels, powdered banana chips, and retail produce. The study aims to establish a reliable spectral reference, evaluate detection limits via dipping and swabbing protocols, and confirm field applicability for food safety surveillance.

Methodology and Instrumentation

Sample Preparation and Analysis Protocols:

• Banana chips: Ground powder spiked with TBZ (100 µg/g to 0.1 µg/g), extracted with 0.1 mol/L NaOH, probed by Ag P-SERS dipping.
• Banana peel: Peel sections treated with methanolic TBZ (10–250 µg/mL), swabbed with methanol-wetted Ag P-SERS strips.
• Direct retail testing: Swabbing of unwashed banana surfaces with Ag P-SERS strips.

Instrument Configuration:

• MISA Advanced portable SERS analyzer with Orbital-Raster-Scan spectrograph
• Attachments: Vial and P-SERS holders
• Ag P-SERS strips and nanoparticle reagents
• Software: Misa Cal V1.0.15; firmware 0.9.33
• Measurement settings: laser power 5 mW, integration time 1 s, 10 averages with raster on

Main Results and Discussion

Spectral Library Creation:

• Generated a distinct Ag P-SERS spectrum of TBZ standard (10 µg/mL) to build the reference entry.

Detection Limits:

• Banana chips: TBZ detected down to 0.1 µg/g via dipping protocol.
• Banana peel: Swab testing revealed TBZ presence at 0.1 µg/g.

Field Validation:

• Direct swabbing of a store-bought banana confirmed TBZ residues through spectral matching with the standard.

Benefits and Practical Applications

The MISA SERS workflow offers:

• Trace-level sensitivity for pesticide residue screening.
• Rapid, on-site analysis without extensive lab infrastructure.
• Flexible sampling methods for diverse sample matrices.
• Portability ideal for field deployment, regulatory checks, and mobile labs.

Future Trends and Opportunities

Emerging directions include:

• Extension to broader pesticide and contaminant panels with expanded spectral libraries.
• Automation and wireless data transfer for real-time monitoring networks.
• Enhanced substrate technologies to improve reproducibility and further lower detection limits.

Conclusion

The Metrohm Instant SERS Analyzer demonstrates robust, sensitive detection of thiabendazole residues on bananas. Its streamlined, portable workflow supports efficient on-site testing and can enhance food safety programs across regulatory and industrial settings.