STUDIES ON THE APPLICATION OF PLATFORM ATOMIZATION TO FURNACE ATOMIC NONTHERMAL EXCITATION SPECTROMETRY FOR THE SIMULTANEOUS MULTIELEMENT ANALYSIS OF ENVIRONMENTAL MATERIALS

Response surface methodology was used to optimize the discharge current and pressure with respect to detection limits for the simultaneous multi-element determination of Al, Cd, Cr, Cu, Fe, Ni and Pb by furnace atomic non-thermal excitation spectrometry (FANES). Comparison of wall and platform atomization showed improved detection limits for most elements with the latter. Despite the use of automatic background correction by wavelength modulation, residual background signals were observed at all lines, those on the Cd, Cu, Fe and Pb channels being rectified by including an 'autozero' procedure in the data processing software. For the remaining elements, spectral interferences disrupted the baseline during the atomization step, although blank subtraction provided satisfactory correction. Nevertheless, the presence of structured background emission poses a potentially serious source of error in FANES measurements. In the multi-element analysis of microwave-assisted digests of three environmental reference materials [National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1572 Citrus Leaves, SRM 1575 Pine Needles and SRM 1645 River Sediment] by platform-equipped FANES, non-spectral interferences arose for all analytes except Cd and Pb. The use of the standard additions method was thus necessary for calibration purposes.