Effects of the mobile phase on the chromatographic separation of l-lysine and 5-aminovaleric acid

Abstract

5-Aminovaleric acid (5AVA), an attractive bio-based carbon-5 building block for polymer synthesis, is produced from l-lysine. However, their structural similarity makes separating 5AVA from l-lysine challenging. The simulated moving bed (SMB), continuous chromatographic separation process provides a solution with high productivity and low eluent consumption. Here, the effects of the mobile phase on the separation of 5AVA and l-lysine on a C18 column are reported. Pre-column derivatization using diethylethoxymethylene malonate enhanced the detection sensitivity and separation performance, which was strongly affected by the phosphate buffer pH. A 70/30 (v/v) mobile phase of 20 mM phosphate buffer at pH 6.8 and acetonitrile showed the best separation performance in isocratic mode. The selectivity at adsorption equilibrium was determined from pulse experiments, and the optimal operating conditions of the SMB process were determined from the equilibrium constants of both components. The feasibility of separating 5AVA and l-lysine by the SMB process was confirmed with purity and recovery of greater than 99%. The SMB process using pre-column derivatization can provide the competiveness of the bio-based chemical production because separation processes typically contribute to more than 70% of the total production cost.