Simplex optimization of aluminum analysis by electrothermal atomic absorption spectrometry

A novel simplex method was applied for the systematic selection of optimal concentrations of two matrix modifiers, nitric acid and magnesium nitrate, for aluminum analysis in aqueous samples using electrothermal atomic absorption spectrometry. Independent optimizations of sensitivity were performed over several practical concentration ranges for each matrix modifier and optimum concentrations were chosen by comparison of data obtained for the resulting simplexes. The results indicate a strong interdependency between magnesium and nitric acid in the achievement of conditions for optimum sensitivity. Using the optimized conditions, detection limits of less than 7 parts per billion of aluminum were achieved, with relative standard deviations of less than 10%. A variety of aqueous samples were analyzed yielding relative standard deviations from 2 to 10%.