Evaluation of the influence of interferents in flame atomic absorption spectrometry and correction of the analytical signal by the limit dilution method

Abstract

A procedure has been developed for the evaluation and correction of analyte-interferent interactions, the 'limit dilution method', which allows the required correction factor to be determined by applying the algorithm concerned to measurements, made on successive dilutions of the unknown solution. The effectiveness of the proposed method was tested by applying it to the determination of calcium (which is subject to interference by sulfate or phosphate ions) and magnesium (which is subject to interference by silicate or aluminium ions). The percentage errors obtained when determining the concentrations of the two analytes are less than those obtained using other methods. Deviations of the analytical signal of up to 250% can readily be corrected. The proposed procedure allows the corrected absorbance-concentration relationship to be linearized even in the presence of interferents.