A study of spectral line profiles in carbon furnace atomic emission spectrometry

Abstract

Carbon furnace atomic emission line profiles of eight elements have been studied using an echelle spectrometer, incorporating a wavelength modulation system. Furnace emission line widths were observed to increase with analyte concentration and in some cases may be of the order of 0.1 nm at 1000 μg ml −1. At low μg ml −1 concentrations, furnace atomic emission line widths for calcium, sodium, chromium, manganese and iron appear to be similar to the corresponding flame emission line widths measured using the same instrument system. Atomic absorption line widths measured for both furnace and flame atomisers are found to be comparable to the emission line widths. The effect of instrumental broadening was estimated by the measurement of hollow cathode lamp line widths to be approximately 0.002–0.003 nm. Self-reversal of atomic emission line profiles has been observed for a number of elements in the concentration range 1–1000 μg ml −1. Calibration graph curvature is attributed to selfabsorption at relatively low concentrations and to self-reversal at concentrations in excess of 1000 times the detection limit. For the spectrometer system used in the present studies, calibration graph linearity is shown to be limited only by line broadening across the modulation interval.