Flow-Injection Determination of Iron Based on Its Catalysis on the Oxidation Reaction of Xylenol Orange by Potassium Bromate

Abstract

A flow injection system is proposed for catalytic kinetic spectrophotometric determination of trace iron(II + III). The involved reaction is based on the catalytic effect of iron(III) on oxidation reaction of xylenol orange by potassium bromate to form a blue-violet complex. Iron(II) is also determined, being oxidized to iron(III) by potassium bromate. The calibration graph is linear in the range of 0.02–10.0 µg l−1 and 10.0–1100 µg l−1. The relative standard deviation is 1.5% for 4.0 µg l−1 iron(III) and 2.3% for 60.0µg l−1 iron(III) (n = 11). The presented system was applied successfully to the determination of iron in natural waters.