A Study of the Influence of Buffers on the Accuracy and Sensitivity of Spectrochemical Results

Abstract

A method is described that allows the simultaneous estimation of buffer efficiency and loss of sensitivity caused by buffer dilution. The smallest amount of buffer, which is necessary to eliminate the effect of the matrices satisfactorily, can be determined. In this way an unnecessary loss of sensitivity due to too high a buffer dilution, can be avoided. The method is based on the study of the behaviour of the analysis lines of a number of elements present in two matrices with different behaviour and diluted with successively increasing buffer amounts. An application of this method is given for a specific rapid evaporation procedure using CuO and Li₂CO₃ as buffers. The dependence of the arc temperature on buffer type and concentration is discussed for both matrices. It is shown that the trend of the relative and of the absolute sensitivity limits with buffer concentration can be estimated from the behaviour of the log intensity value and of the log of the intensity/weight ratio. The smallest satisfactory buffer amounts established for CuO and Li₂CO₃, agree with recommendations in the literature.