Flow injection calibration of inductively coupled plasma atomic emission spectrometry using the generalised standard additions method

Abstract

The generalised standard additions method (GSAM), employing least-squares regression, provides a convenient method for obtaining the calibration matrix (K-matrix) in multi-element analysis. The GSAM is based on the response variations obtained after the addition of known incremental amounts of the interfering and test elements to the samples. As application of the GSAM requires a number of additions, automation is recommended for routine analytical work. Any automated procedure for implementing the GSAM should permit a high sampling rate and a low consumption of sample and standard solutions. A flow injection procedure fulfils these requirements. Using a single standard solution, different concentrations may be obtained by a zone sampling process which exploits the concentration gradients established along the dispersed pattern. The proposed procedure involves a flow injection system, with merging zones and zone sampling, coupled to an inductively coupled plasma atomic emission spectrometer and permits 120 measurements per hour and includes the manipulations required by the GSAM. The results obtained by the proposed method show good agreement with the certified values of the rock reference materials. The reproducibility of the K-matrix, evaluated by successive GSAM applications, was better than 99.5%.