Batch-To-Batch Variation of Chelex-100 Confounds Metal-Catalysed Oxidation. Leaching of Inhibitory Compounds from A Batch of Chelex-100 and Their Removal by a Pre-Washing Procedure

Abstract

Removal of adventitious redox-active metals from buffers by treatment with Chelex resin is a widely used procedure in free radical research. Use of a new batch of Chelex-100 resin in our laboratory coincided with a sudden inability to oxidise low-density lipoprotein with copper. We found that copper-mediated oxidation of ascorbate in water treated with the same batch of Chelex was inhibited when compared with untreated water and water treated with a different batch of the resin. Washing the Chelex removed the inhibitory effect suggesting that material was leaching from the resin. The washing procedure for Chelex-100 described is simple and can be scaled up. Oxidation of ascorbate with low concentrations of copper can be used to test the quality of batches of the resin.

Key Words:

• transition metals
• ascorbic acid
• redox reactions