Modular and conservative procedure for the quantification of amino functionalities bonded to solid porous matrices

Area of Science:

• Materials Science
• Analytical Chemistry
• Surface Chemistry

Background:

• Amino-functionalized silica materials are crucial for CO2 capture and chromatography.
• These materials are particularly effective as stationary phases in Hydrophilic Interaction Liquid Chromatography (HILIC) for separating complex mixtures like carbohydrates.
• Accurate quantification of surface functional groups is essential for optimizing material performance.

Purpose of the Study:

• To develop a simple, efficient, and non-destructive method for quantifying the density of basic (amino) groups on solid silica matrices.
• To enable full recovery of the analyzed material after quantification.
• To assess the uncertainty associated with the developed quantification method.

Main Methods:

• Utilized a preventive acid-base reaction between surface amino groups and 3,5-dinitrobenzoic acid (DNBA).
• Quantified the bound basic functionalities via UV-spectrophotometric retro-titration or High-Performance Liquid Chromatography (HPLC).
• Employed an acid or basic displacement strategy to recover DNBA from the solid matrix.

Main Results:

• Presented an original, operationally simple procedure for quantifying surface amino group density.
• Achieved full recovery of the analyzed solid materials.
• Determined the uncertainty of the density measurements to be 13%.

Conclusions:

• The developed method provides a reliable and straightforward way to quantify amino group density on silica-based materials.
• This technique is valuable for quality control and optimization of materials used in CO2 capture and HILIC applications.
• The ability to recover the material is advantageous for further characterization or reuse.