The vaporized amounts, vaporization behavior and spectral line intensity of gold in graphite powder by arc discharge

The relations between vaporized amounts, vaporization behavior and spectral line intensity of gold in graphite powder have been examined with graphite electrodes under varying arc discharge conditions and buffer concentrations. Standard samples were prepared with highly purified graphite powder, 100 ppm of gold as auric chloride and various amounts of lithium fluoride as a spectrographic buffer substance. The element was excited by d. c. arc discharge, and the concentration of gold remaining in graphite powder after the dischage was measured by the neutron activation analysis. It was clarified that the vaporized amounts and vaporization behavior depended mostly on the electrode temperature. As an arc current increased, the vaporized amounts increased and the temperature of an anode was raised. Under the experimental conditions including d. c. 14.4A, 14.6V, discharge time 60 sec, electrode gap 3 mm, and 2.0% of lithium fluoride, the vaporized amounts were 2×10-8 g/mg sample at the anode crater in argon atmosphere, and 6.8×10-8 g/mg sample at the anode crater in helium atmosphere. The emission line intensity of Au:2675.9Å depended on the vaporized amounts of gold in argon atmosphere, but not depended on the vaporized amounts of gold in helium atmosphere.