Trace Detection of Pyrimethanil in Wine

Importance of the Topic

Pyrimethanil is widely used in viticulture to protect grapevines against fungal diseases. Despite low residue levels found in finished wines, concerns about its potential carcinogenicity and multi-organ toxicity have led regulatory bodies in the US and EU to set strict maximum limits. Rapid onsite detection of trace fungicide residues ensures consumer safety and supports quality control throughout wine production and distribution.

Aims and Study Overview

This study demonstrates a field-deployable protocol using Metrohm Instant SERS Analyzer Misa for trace detection of pyrimethanil in white wine. Key objectives include establishing a reference SERS spectrum, validating a simple extraction workflow, and evaluating detection limits relative to regulatory thresholds.

Methodology and Instrumentation

The approach pairs surface enhanced Raman scattering with gold nanoparticle substrates to achieve sensitive analyte identification. Sample preparation involves liquid–liquid extraction using chloroform, phase separation, evaporation of the organic layer, and reconstitution in gold colloid with added sodium chloride to promote nanoparticle aggregation.

Instrumentation details

• Misa Advanced analyzer with Orbital-Raster-Scan spectrograph
• Misa Vial Attachment for liquid samples
• ID Kit Au NP containing gold colloid, vials, spatula, pipettes
• Laser power 5 units, integration time 10 seconds, 10 spectral averages, raster scan enabled

Main Results and Discussion

Baseline-corrected SERS spectra of spiked wine samples revealed clear pyrimethanil peaks down to 100 ng/mL. This limit of detection is 50 times lower than the maximum permissible concentration of 5 µg/mL in finished wine. Overlaid spectra confirm spectral reproducibility across the tested concentration range, demonstrating the robustness of the extraction and measurement protocol.

Benefits and Practical Applications

Use of Misa enables rapid, low-cost testing without need for a full laboratory setup. Key advantages include

• Portability for on-site screening during winemaking, storage, shipping, and receiving
• Minimal sample preparation with common reagents
• High throughput potential with integrated data processing and reporting

Future Trends and Opportunities

Advancements in nanoparticle chemistry and instrument miniaturization may further lower detection limits and expand the range of detectable agrochemicals. Integration of automated sample extraction, cloud-based spectral libraries, and machine learning algorithms could enhance real-time decision making for quality assurance in the wine industry and beyond.

Conclusion

The Metrohm Instant SERS Analyzer provides a sensitive and practical solution for pyrimethanil residue analysis in wine. Its field-ready configuration, simple workflow, and sub-ppb detection capability align with regulatory requirements and support routine monitoring to ensure product safety.