Stabilization of the oxide forming elements, lead, thallium and tin, in graphite tubes for graphite furnace atomic absorption spectrometry by intercalation

Oxide forming elements such as Tl, Pb, or Sn show a stabilization to higher pyrolysis temperatures and a well known pulse shift in the atomization signal when the graphite tube is treated with oxygen. The same stabilization can be obtained by pretreatment under gas stop in uncoated tubes and to a lesser extent also in pyrocoated tubes due to a complete reduction to the metal. Intercalation of the metal atoms into the graphite layers is proposed as the mechanism for this stabilization. A method is described which makes it possible to distinguish between intercalated and surface-deposited metal atoms by reoxidation.