Determination of non-protein-bound iron in rat tissue by ion chromatography with electrochemical detection.

A new, rapid, sensitive, and specific method combining ion chromatography with electrochemical detection was developed for measuring non-protein-bound Fe(II) and Fe(III) in biological samples. The procedure was based on the separation of the iron-diethylenetriaminepentaacetic acid complex formed directly on the chromatographic column with anion-exchange resin followed by electrochemical detection. The method enabled more than 0.5 microM Fe(II) and Fe(III) to be determined for injection volumes of 10 microliters. This method was applicable for the determination of Fe(II) and Fe(III) in ultrafiltrates of the rat liver cytosolic fraction. It was found that release of iron from iron-bound proteins was pH dependent and that non-protein-bound iron in the tissues was determined in a ferrous state at low pH values.