Surface enhanced Raman spectroscopy in microchip electrophoresis.

Area of Science:

• Analytical Chemistry
• Chemical Engineering
• Spectroscopy

Background:

• Microchip capillary electrophoresis (MCE) offers high separation power but lacks sensitive detection.
• Surface-enhanced Raman spectroscopy (SERS) provides sensitive, label-free chemical identification but struggles with speed.
• On-line coupling of MCE and SERS aims to combine their strengths for enhanced analytical performance.

Purpose of the Study:

• To develop and evaluate a novel microfluidic device for on-line MCE-SERS coupling.
• To improve the sensitivity and speed of SERS detection for electrophoretically separated analytes.
• To demonstrate the applicability of the MCE-SERS system for complex sample analysis.

Main Methods:

• A glass microfluidic chip with a unique dosing structure was designed for on-line silver nanoparticle (Ag-NP) delivery.
• The dosing structure introduces Ag-NPs to separated zones within the MCE channel for SERS analysis.
• The system was tested using a rhodamine model mixture and subsequently applied to analyze riboflavin in barbecue sauce.

Main Results:

• The MCE-SERS chip successfully achieved on-the-fly SERS-spectra acquisition for separated compounds.
• Analysis of a rhodamine mixture yielded migration time relative standard deviations (RSD) below 1.5% within 90 seconds.
• The system demonstrated successful application for analyzing the food additive riboflavin in a complex matrix (barbecue sauce).

Conclusions:

• The developed MCE-SERS microfluidic device effectively integrates separation and sensitive detection.
• This novel approach enhances SERS sensitivity and speed for electrophoretically separated analytes.
• The MCE-SERS system shows significant potential for rapid chemical analysis in complex samples.