Low-resolution monochromator system for electrothermal atomisation atomic emission spectrometry with probe atomisation

Abstract

A 174-mm focal length Ebert monochromator has been used to construct a low-cost spectrometer for ETA-AES. An oscillating quartz refractor plate was positioned in front of the exit slit inside the monochromator, to achieve rapid automatic background correction by wavelength modulation. The spectrometer was used to measure Cd, Cr, Cu, Mn, Mo, Ni, Pb and V atomic emission from a Perkin-Elmer HGA-72 atomiser modified for probe atomisation and equipped with totally pyrolytic graphite tubes. The µg l^–1 detection limits obtained for Cd, Cr, Cu, Mn and Pb were a factor of 4–13 poorer than those achieved previously with an échelle spectrometer and similar atomisation system. The variation in detection limits can be explained partly by difference in the optical characteristics of the spectrometer systems. The results obtained suggest that satisfactory analytical performance can be achieved in ETA-AES by use of an inexpensive low-resolution monochromator.