The absorptiometric determination of aluminium in water. A comparison of some chromogenic reagents and the development of an improved method

Abstract

The properties of chromogenic reagents used for the absorptiometric determination of aluminium in water are compared, and an experimental comparison of catechol violet, Eriochrome cyanine R and stilbazo has been made. Catechol violet is considered to be the most suitable and a method involving the use of this reagent has been developed. When using this method, the standard deviation of the analytical results varied from 0·004 to 0·008 mg l^–1 of aluminium for concentrations of 0·05 and 0·3 mg l^–1 of aluminium, respectively. With the exception of fluoride, substances normally present in treated waters did not cause important interference. The effect of fluoride (l mg l^–1 or less) is tolerable for most purposes, but appreciably greater concentrations require preliminary removal of fluoride or correction for its effect. Satisfactory results have been obtained with the method in six other laboratories. The method is simple and rapid; ten samples can be analysed in approximately 1 1/2 hours. The method has advantages over other commonly used methods, and is recommended for use in water analysis laboratories.