An absorbance-based micro-fluidic sensor for diffusion coefficient and molar mass determinations.

Area of Science:

• Analytical Chemistry
• Microfluidics
• Chemometrics

Background:

• Traditional analytical methods often require multiple steps and specialized equipment for comprehensive analyte characterization.
• Simultaneous detection and deconvolution of complex mixtures remain a challenge in analytical sciences.

Purpose of the Study:

• To introduce and validate the H-Sensor, a novel micro-fluidic device for simultaneous absorbance measurements.
• To develop a theoretical model correlating signal ratios to analyte diffusion coefficients.
• To demonstrate the H-Sensor's capability for chromatographic and spectroscopic deconvolution of mixtures using chemometric methods.

Main Methods:

• The H-Sensor utilizes two off-chip absorbance flow cells for simultaneous measurements.
• A theoretical model was developed to relate the ratio of absorbance signals to the analyte diffusion coefficient.
• Flow Injection Analysis (FIA) and High-Performance Liquid Chromatography (HPLC) were employed for experimental validation.
• Classical Least Squares (CLS) and Generalized Rank Annihilation Method (GRAM) were used for signal deconvolution.

Main Results:

• The H-Sensor successfully provided simultaneous absorbance measurements, enabling the calculation of analyte diffusion coefficients.
• Experimental data validated the theoretical model for sensing mechanism and diffusion coefficient determination.
• The H-Sensor generated second-order HPLC chromatograms, facilitating deconvolution of mixtures.
• The Generalized Rank Annihilation Method (GRAM) achieved accurate deconvolution with a quantitative error below 10% at chromatographic resolutions of 0.25 and above.

Conclusions:

• The H-Sensor is a versatile micro-fluidic device for simultaneous absorbance detection and analyte diffusion coefficient determination.
• The integration of the H-Sensor with chemometric methods like GRAM allows for effective deconvolution of complex mixtures in HPLC.
• This technology offers a significant advancement in analytical chemistry, providing simultaneous spectroscopic and chromatographic information.