Suggested Modified Aluminon Method for Aluminum Determination

This article presents a modified aluminon method for aluminum determination. The procedure developed by the Subcommittee on Aluminum has been tested in a representative number of laboratories. The comments received have, in general, been favorable, and a modified aluminon method has been developed that is accurate and sensitive and that has reproducible results. The method is based on the fact that dilute aluminum solutions, buffered to a pH of about 4.0, produce with aluminon a red to pink lake that exhibits maximum absorption at about 525 mμ. The intensity of the developed color is influenced by the aluminum concentration, reaction time, temperature, pH, quality of the aluminon used, and concentration of the various accompanying ions in the sample. This article discusses interference, apparatus, general reagents, general procedure, procedure for removal of fluoride interference, calculation, and precision and accuracy.