Purification of non-toxic, biodegradable arginine-based gemini surfactants, bis(Args), by ion exchange chromatography

This paper presents an environmentally improved procedure for the preparative purification of a series of arginine-based gemini surfactants. The technique used was cation-exchange chromatography. Mixtures of boric-borate buffer, co-solvent (ethanol), and sodium chloride were tested as eluents. The influence of the buffer pH and the amount of co-solvent on the chromatographic process was studied for the model compound bis(Nalpha-lauroyl-L-arginine) 1,3-propanediamide dihydrochloride, C3(LA)2, and purification conditions were established. The method was scaled-up to the multigram level for C3(LA)2 and the rest of the series. The proposed preparative procedure involves simple equipment, low cost materials, and minimal amounts of solvent (water/ethanol), with low toxicity.