Abstract

A continuum source atomic absorption spectrometry (CS-AAS) instrument consisting of a high-resolution echelle spectrometer and a two dimensional charge coupled device (2D-CCD) with a high frame rate was used to measure intensities as a function of height and time in the graphite furnace. The image of the furnace was reduced to a height less than that of the entrance slit to allow the full vertical profile of the furnace to be viewed. Spatially resolved absorbance, A_SR, was computed as the average of the computed absorbances for each of the vertical elements, or pixels. Spatially integrated absorbance, A_SI, was computed by summing the intensities for each of the vertical pixels and computing a single absorbance. A_SR and A_SI were computed for three viewing regions: the full image of the furnace (a 6 mm region), the image of the region above the platform (a 4 mm region) and a 2 mm region anywhere within the furnace, which corresponds to a sub-sample of the furnace image with a 2 mm slit height. Photometric errors induced by analyte non-homogeneity were greatest for platform atomization when the full furnace image was viewed and for either platform or wall atomization when a 2 mm sub-section of the furnace was viewed. These photometric errors had the potential for producing analytical errors only when a 2 mm sub-section was viewed. Analytical errors introduced by photometric errors for just four elements in a single standard reference material, Citrus Leaves, ranged from +5% to −15%. These results suggest that photometric error is problematic for conventional line source AAS.