FURNACE ATOMIC NONTHERMAL EXCITATION SPECTROMETRY WITH THE FURNACE AS A HOLLOW ANODE

Furnace atomic non-thermal excitation spectrometry with the furnace as the hollow anode (HA-FANES) was characterised for the determination of Cd and Cu. Operating in the abnormal glow discharge region, the current was limited by the current density at the cathode. Higher currents were attained with a larger diameter cathode and at higher pressures. The emission signals were dependent on the current density. More intense signals were observed when viewing the top and left of the discharge. This positional dependence of the signal strength was much more pronounced for Cu than for Cd. Peak areas and signal to noise ratios increased linearly with the discharge pressure to a maximum of 25.3 kPa. Emission intensities were constant as a function of the discharge current above a threshold of 20 mA for Cd and 50 mA for Cu. Both Cd and Cu gave the largest peak areas at the lowest atomisation temperature (1390°C). The peak areas decreased roughly in proportion to the increased diffusion coefficients at higher temperatures. The detection limits for HA-FANES (0.8 and 1.5 pg for Cd and Cu, respectively) are comparable to those for conventional FANES with the furnace as a hollow cathode and graphite furnace atomic absorption spectrometry.