Detection limits for electrothermal atomisation-coherent forward scattering spectrometry using an optical multi-channel analyser

Abstract

An optical multi-channel analyser, which records a spectral interval of 55, 110 or 220nm in width was used to provide a multi-element capability for coherent forward scattering (CFS) spectrometry. The lower limit of the UV range that can be used coincides with the 213.9-nm line of Zn. This limitation is caused by spectral transmittance of the calcite polarisers. The samples were atomised by a laboratory-constructed graphite furnace, the performance of which is not state of the art. In order to optimise its efficiency, different atomisation techniques (off the wall, platform and tube-in-tube) were employed and tested. With the CFS spectrometer in the Voigt configuration, detection limits for CD, Pb, Mn, Fe and Cr were determined. The detection limits of the five elements were determined independently for each element under individually optimised conditions. The absolute detection limits vary between 5 and 60 pg. With a sample volume of 10 µl the corresponding relative detection limits obtained with CFS are comparable to those of inductively coupled plasma atomic emission spectrometers.