EXPANSION OF DYNAMIC WORKING RANGE AND CORRECTION FOR INTERFERENCES IN FLAME ATOMIC-ABSORPTION SPECTROMETRY USING FLOW-INJECTION GRADIENT RATIO CALIBRATION WITH A SINGLE STANDARD

Flow injection not only offers atomic absorption spectrometry a means for fully automated sample management but enhances the zeroth-order atomic absorption technique to a first-order technique by introducing a new predictor variable called dispersion. By use of the total information contained in the transient signal caused by this dispersion process instead of only peak height or peak area, the dynamic range of flame atomic absorption spectrometry can be substantially expanded. A straightforward algorithm, named CLAIR (calibration graph linearization and interfered signal reconstruction), based on gradient ratio evaluation and capable of utilizing the additional information in the transient signal for calibration and interference correction is proposed. With this algorithm the entire working range of the instrument can be calibrated by using only one reference solution and thus avoiding any problems due to calibration graph curvature or instrumental drift. At the same time this algorithm also corrects for multiplicative interference effects, so that accurate results can be obtained even in the presence of interfering matrices.