Competitive Binding Investigations and Quantitation in Surface-Enhanced Raman Spectra of Binary Dye Mixtures

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Nanomaterials

Background:

• Surface-enhanced Raman spectroscopy (SERS) offers high sensitivity for molecular detection.
• Quantifying analytes in mixtures using SERS presents challenges due to competitive adsorption.
• Alizarin and purpurin are common dyes with distinct spectral properties.

Purpose of the Study:

• To develop and validate a SERS method for quantifying alizarin and purpurin in binary mixtures.
• To investigate the competitive adsorption behavior of these dyes on silver nanoparticles.
• To compare different calibration models for optimal quantitative analysis.

Main Methods:

• SERS measurements of alizarin and purpurin mixtures using silver nanoparticles.
• Centrifugation to study dye adsorption dynamics.
• Development of calibration curves using standard calibration and Langmuir isotherm models.
• Synthesis of stable silver nanoparticles via microwave irradiation.

Main Results:

• Both alizarin and purpurin adsorb simultaneously onto silver nanoparticles, with the stronger adsorbing dye dominating spectral signals.
• Peak height calibration, accounting for peak shifts, provides more accurate quantitation than peak area calibration.
• Microwave-synthesized nanoparticles exhibit excellent stability and minimal batch-to-batch variation over one year.

Conclusions:

• SERS is a viable technique for quantifying dyes in mixtures by careful peak selection.
• Peak height calibration is recommended for accurate SERS-based dye quantitation.
• Stable, reproducible nanoparticles are crucial for reliable SERS analysis.