COMPARATIVE STUDIES ON THE METAL SORPTION CHARACTERISTICS OF CHELATING GELS FOR IMMOBILIZED METAL ION AFFINITY CHROMATOGRAPHY

Abstract

A systematic investigation of the metal sorption and leaching characteristics of two chelating gels viz., iminodiacetic acid (IDA) and Tris(2-aminoethyl)amine bound to Sepharose 6B, under varying chemical conditions relevant for immobilized metal ion affinity chromatography (IMAC) of proteins (e.g., buffer salts, pH (4–9), ionic strength (0–3 M NaCl), feed metal concentration (0–50 mM)) has been undertaken. The studies were carried out for the two most frequently used metal ions namely, Cu(II) and Ni(II). Results indicated that the metal sorption capacities of these chelating gels show strong dependence on the changes in pH around them. However, the effect of ionic strength and feed metal concentration on metal sorption capacities is moderate. On the basis of these investigations, conditions for optimum sorption capacities were identified. Further, metal leaching studies were conducted for various solution conditions (pH, ionic strength) on these gels to assess their suitability for use in protein separations. These studies may provide an outset for preparing stable metal chelated gels for protein separations.

Keywords:

• Chelating gels
• Iminodiacetic acid
• Tris(2-aminoethyl)amine
• Metal sorption
• Metal leaching

ACKNOWLEDGMENTS

S. Sharma thanks the Council for Scientific and Industrial Research (CSIR), India for providing financial support. The authors gratefully acknowledge Prof. P. D. Grover and Dr. S. S. Sambi of Chemical Engineering Department, Indian Institute of Technology, Delhi for atomic absorption facility; Dr. C. R. Jagga of Industrial Tribology, Machine Dynamics and Machine Engineering Centre (ITMMEC), Indian Institute of Technology, Delhi and Analytical Division-Indian Oil Corporation, Faridabad for providing ICP-AES facility for the analysis of the metal leaching samples.