Organic Solvent as Internal Standards for Quantitative and High-Throughput Liquid Interfacial SERS Analysis in...

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) offers substrate-free analysis but requires uniform fabrication and stable internal standards (IS) for biphasic liquid interfaces.
• Challenges exist in precisely locating IS tags and analytes within the same structure under harsh interfacial conditions.

Purpose of the Study:

• To develop a fast, batch fabrication strategy for self-ordered gold nanoparticle (GNP) arrays at a biphasic liquid interface for SERS analysis.
• To utilize acetone as a phase-crossing inducer and internal standard for enhanced uniformity and sensitivity in pesticide detection.

Main Methods:

• Self-ordered dense GNP arrays were formed at the cyclohexane/water interface in 96-well plates using acetone as a phase-crossing inducer.
• Acetone extracted pesticide molecules and simultaneously served as an internal standard for SERS signal calibration.
• The platform was tested for detecting pesticide residues on fruit peels using surface-enhanced Raman scattering (SERS).

Main Results:

• Achieved excellent uniformity with a relative standard deviation (RSD) of 5.9% (vs. 14.5% without IS correction).
• Demonstrated high sensitivity with a limit of detection (LOD) of 1 nM for thiram and detection levels of nanograms per square centimeter (ng/cm²) for pesticide residues.
• Successfully performed multiplex and two-phase detection of oil-soluble (thiabendazole) and water-soluble (thiram) pesticides.

Conclusions:

• The developed platform enables rapid, quantitative, and high-throughput SERS analysis of pesticide residues at fruit peels.
• Acetone as a phase-crossing inducer and internal standard significantly improves uniformity and facilitates multiplex sampling.
• This approach offers a convenient and versatile tool for on-site sensing, comparable to microplate readers.