Beyond traditional SERS: Integrating pH control and renewable screen-printed electrode for EC-SERS detection

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Electrochemistry

Background:

• Surface-enhanced Raman spectroscopy (SERS) faces challenges in detecting small, weakly adsorbing pesticides due to limited analyte enrichment and field deployability.
• Existing methods struggle with sensitivity and portability for real-time pesticide residue analysis.

Purpose of the Study:

• To develop a portable electrochemical SERS (EC-SERS) platform for sensitive and field-deployable pesticide detection.
• To overcome the limitations of conventional SERS for analyzing pesticides like imidacloprid in food matrices.

Main Methods:

• Integration of a redox-roughened screen-printed silver electrode (SPE-Ag) with a smartphone-controlled mini-potentiostat.
• Electrochemical pre-concentration of protonated imidacloprid onto plasmonic "hot spots" at -1.0 V and pH 2.
• Validation using spiked samples of Pisum sativum L. and Allium fistulosum L.

Main Results:

• Achieved a 27-fold signal enhancement for imidacloprid detection.
• Established a limit of detection (LOD) of 1.5 nM for imidacloprid, a four-order-of-magnitude improvement over conventional SERS.
• Demonstrated excellent reproducibility (inter-batch RSD 5.6%), uniformity (intra-chip RSD 5.8%), and stability (90% signal retention over 10 weeks).
• Recoveries in spiked food samples ranged from 90.65% to 103.04%.

Conclusions:

• The developed low-cost, portable EC-SERS platform enables rapid screening of pesticide residues in real food matrices.
• This technology shows significant potential for enhancing food safety monitoring.
• The renewable SPE-Ag supports over 15 adsorption-desorption cycles, indicating practical reusability.