A novel procedure for rapid and accurated quantification of amino functionalities bonded to solid porous matrices

Recently, solid porous matrices functionalized with amino groups have found wide use in the field of CO2 capture and storage technologies1 as well as in separation science for chromatographic applications. In fact, they are profitably used as stationary phases for HILIC (Hydrophilic Interaction Liquid Chromatography) separations, which allow the effective resolution of interesting compound classes (e.g. mixtures of mono- or oligo-saccharides). In this study, we developed a new method to quantify the density of basic sites on solid matrices (in particular amino groups). The procedure is fast and easy, and not destructive towards the analyzed material. The approach is based on the preventive salification of the basic groups linked to the solid by 3,5-dinitrobenzoic acid (DNBA). Quantification of the basic functionalities is then performed by an UV-spectrophotometric retrotitration of the salified solid matrix (or, alternatively, by reverse phase HPLC approach), resorting to a preventive either acid or basic displacement of DNBA from the solid material.