Extension of the dynamic range in Zeeman graphite furnace atomic absorption spectrometry

In order to extend the dynamic range of Zeeman graphite furnace atomic absorption spectrometry (GFAAS), we propose a method to restore the dip formed in the region of the absorption pulse maximum and resulting from the roll-over of the calibration curve. A previously proposed model (B. V. L'vov et al., Spectrochim. Acta 47B, 1187 (1992)) for the ascending part of the Zeeman calibration curve and one developed on the same basis for the descending part of the curve has made it possible to linearize the calibration graph over the entire range of absorption variation in terms of two parameters: roll-over absorbance, A r, and Zeeman sensitivity ratio, R. The use of the dip extends the dynamic range, on average, by an order of magnitude compared to a range restricted by the roll-over point. This makes the full dynamic range of Zeeman GFAAS 3–4 orders of magnitude higher than the characteristic mass, m 0. The method has been tested on three elements (Be, Bi and Cd) having different Á r and R parameters. The measurement error in the determination of analyte mass for large signals in the dip region does not exceed that for signals of average magnitude. The correction of spectral interference in the dip region is approximately equivalent to the continuum background correction with a single light source.