Synthesis and chromatographic characteristics of iminodisuccinic acid-functionalized silica stationary phase

In this study, we developed a multifunctional chromatographic medium by using iminodisuccinic acid (IDS) as ligand, γ-glycidoxypropyltrimethoxysilane (γ-GLDP) as spacer arm and silica as matrix. The medium was characterized by fourier transform infrared spectrometry (FT-IR). Binding capacity of IDS on chromatographic medium was determined by potentiometric titration. The effect of mass ratios (w/w) between silica and IDS on the medium synthesis was discussed. The optimal ratio of matrix, spacer arm and ligand was 1.5g: 2.0mL: 4.6g. Based on different chromatographic modes, protein mixtures of bovine serum albumin, ribonuclease and lysozyme were successfully separated with IDS-Silica column and IDS-Cu(II)-Silica column, respectively. To examine metal chelating behavior of IDS-Silica stationary phase, optimal geometries and related parameters of complexes formed by IDS with Fe³⁺, Cu²⁺, Ni²⁺, Zn²⁺, Co²⁺ and Ca²⁺ were achieved by quantum computing. The stabilities of the complexes were predicted according to the results of theoretical calculation. Sorption capacities of IDS-Silica stationary phase for metal ions were determined by using offline frontal chromatography (FC) combined with inductively coupled plasma atomic emission spectrometry (ICP-AES). A good agreement was found between simulating results and experimental observations. The order of chelating strength of IDS-Silica medium for metal ions was Fe³⁺>Cu²⁺>Ni²⁺>Zn²⁺>Co²⁺>Ca²⁺. Compared with IDA-Silica, Asp-Silica and Glu-Silica stationary phases, IDS-Silica displayed a stronger chelating property for metal ion.