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approaches have been made, many of which have now been superseded. The detection limits of the
technique were, however, comparable to those obtainable by electrothermal AAS (ETAAS). Excitation
sources that rely on non-thermal processes are often preferable to those that rely on thermal processes
because of their low background emission. Two such techniques are discussed briefly below.

3.7.1 Furnace Atomic Non-thermal Excitation Spectrometry (FANES).

The procedure used for this technique is similar to that for ETAAS. The sample is pipetted into the
graphite tube and dried and ashed in the normal manner. The system is then evacuated, before allowing
argon to partially re-pressurize it. A glow discharge is then generated and the sample atomized into it by
heating the graphite tube. Once in the discharge, the atoms become excited and give off light, the
intensity of which is measured. The technique, although popular for a while, is complex and hence
inconvenient, because of the necessity to work at low pressure (< 200 Torr). A few research papers are
still published each year but, as yet, the technique has not found universal acceptance.

3.7.2 Furnace Atomization Plasma Emission Spectrometry (FAPES)

By coupling an RF generator to a graphite furnace containing a central tungsten electrode, an
atmospheric pressure plasma within the tube is formed. Helium is usually used rather than argon as the
sheath and internal purge gas. The sample is pipetted into the tube, dried and ashed in the normal way
and then an RF power of typically 50 W is applied. The plasma formed around the central tungsten
electrode is allowed to burn for 20 s, and then the high temperature atomization cycle of the programme
is initiated. The atoms pass into the plasma and the light they emit is measured. The RF power is then
turned off and, after the normal cooling stage, the entire sequence may be repeated.

Q. What are the advantages and disadvantages of these alternative techniques when compared with
conventional electrothermal atomization?