Abstract

Interference effects caused by calcium when determining sulfur from extracted soil samples by inductively coupled plasma optical emission spectrometry (ICP-OES) were studied. The multiple linear regression (MLR) model was utilized for this purpose. Interferences were classified according to how they affected the regression coefficients in the MLR model. Although MLR methodology has been widely used in different instrumental techniques, this was a new viewpoint in ICP-OES methodology. It was observed that calcium caused a severe spectral overlap at the sulfur emission line. Calcium had been reported to cause matrix effects in earlier studies, but these were not observed in this study. The MLR model was also utilized as a calibration function to correct the observed spectral interference. The developed method proved to be accurate and easy to use when compared to two separate single variable regression models previously used to correct spectral interference. The number of standards required for calibration was reduced from 12 to 6. Thus, the time required for calibration or re-calibration was decreased substantially.