Graphite furnace method according to the elements to be tested and sample selection of suitable graphite tube, graphite tubes are now commonly used in three, ordinary graphite tube, pyrolytic graphite tube and platform graphite tube. Ordinary graphite tube made of ordinary graphite, the most widely used. Due to the porous nature of graphite, the liquid sample will have some penetration in the graphite wall. Pyrolytic graphite tubes are pyrolyzed by the CVD method on the surface of ordinary graphite tubes, with a metallic, shiny surface, with less sample penetration on the tube wall. The platform graphite tube is equipped with a flat plate (platform)