Atom release of Mn, Co, Ag and Tl in a graphite furnace atomizerwith and without palladium modifier

Abstract

The activation energies of atom release for Mn, Co, Ag and Tl from a graphite surface are determined by using Smets' method both in the absence and presence of palladium. In the absence of Pd, the activation energies are found to be 414 ± 4, 363 ± 2 and 180 ± 6 kJ mol for Mn, Co and Tl, respectively, whilst that of Ag is mass dependent. In the presence of palladium, the activation energies are found to be 414 ± 3, 362 ± 3, 341 ± 6 and 288 ± 3 kJ mol for Mn, Co, Ag and Tl, respectively. For the medium volatility elements, the values of Mn and Co are similar to those in the absence of Pd, while for the relatively high volatility elements, like Ag and Tl, the activation energies are increased in the presence of Pd. The stabilizing effect of Pd is rather pronounced for the relatively volatile elements, which can be stabilized to a higher tolerable pyrolysis temperature in the graphite atomizer owing to the formation of a relatively strong Pd - analyte interaction. The relatively weak interaction between palladium and Mn or Co accounts for the similar activation energies obtained in the absence and presence of Pd.