Trace Detection of Acetamiprid on Raisins

Significance of the Topic

Raisins are a popular snack but frequently show high levels of multiple pesticide residues, raising concerns about the unknown long-term effects of combined exposures. Rapid, on-site screening techniques are crucial to safeguard consumer health and ensure food safety.

Objectives and Study Overview

This study evaluates the Metrohm Instant SERS Analyzer (MISA) for swift, trace-level detection of the neonicotinoid pesticide acetamiprid on commercial raisins. The main goals are to achieve detection at regulatory limits and to explore methods for enhancing sensitivity.

Used Instrumentation

• MISA Advanced: Portable Surface-Enhanced Raman Scattering analyzer with Orbital-Raster-Scan spectrograph, Vial and P-SERS attachments.
• Silver colloidal solution for SERS enhancement.

Methodology

Portions of raisins were spiked with acetamiprid at concentrations from 100 µg/mL to 500 ng/mL. Each sample was extracted with dichloromethane via vortex mixing and resting periods, followed by solvent evaporation. The residue was mixed with silver colloid and salt to induce SERS activity, then measured using the MISA vial attachment.

Main Results and Discussion

SERS spectra of raisin extracts matched the reference acetamiprid signature, with peak intensities correlating to concentration. Detection down to 500 ng/mL was demonstrated. Sensitivity improvements were achieved by combining multiple extract aliquots into a single measurement and extending integration times, which enhanced signal strength at trace levels. Nonlinear intensity response at low concentrations reflected extraction variability and SERS effects near detection limits.

Benefits and Practical Applications

The compact, user-friendly MISA enables rapid, on-site screening for pesticide residues, reducing dependence on centralized laboratories. Its dedicated SERS substrates and spectral libraries support efficient compliance testing and quality control in food production and inspection.

Future Trends and Opportunities

• Integration of machine learning algorithms for automated spectral analysis.
• Development of novel SERS substrates to further boost sensitivity.
• Expansion of portable SERS platforms for diverse food matrices and field applications.

Conclusion

The Metrohm Instant SERS Analyzer offers a powerful solution for rapid, sensitive detection of acetamiprid on raisins, promoting consumer safety through efficient, on-site screening and informed decision-making in food quality assurance.

References

1. USDA Agricultural Marketing Service. Raisin Grades & Standards.
2. Environmental Working Group. Shopper’s Guide to Pesticides in Produce.
3. European Food Safety Authority. National Summary Reports on Pesticide Residue Analysis Performed in 2020.