Performance characteristics for the spectrophotometric determination of total iron in freshwater using hydrochloric acid

Abstract

A method is described for the determination of total iron in freshwater using a wet-oxidation procedure followed by spectrophotometric measurement in 5.93 ± 0.07 M hydrochloric acid.

It has been used successfully in routine analysis for several years and requires only standard equipment and inexpensive reagents. The criterion of detection is 0.009 mg l^–1 for the 95% confidence level. The relative standard deviation at 0.2 mg l^–1 is 4.4% and at 3 mg l^–1 is 1.5% for 19 degrees of freedom. Comprehensive interference tests show that the method is adequately selective for use with freshwater. Copper is the only substance to interfere significantly and below 0.1 mg l^–1 it has a negligible effect.