Sample liquid is vaporized by a thermospray vaporizer (24) with a heated capillary tube (36). The end of the capillary tube (36) is inserted into a graphite tube furnace (120), while the furnace and a vertical platform in this furnace is at an above-ambient deposition temperature. The vavor spray emerging from the capillary tube is directed towards the platform. Sample substances are deposited on the platform, while vaporized solvent is drawn off by a vacuum. Larger quantities of sample without the solvent can be deposited in this way on a small platform. This permits using the platform technique without the limitations as to the quantity of the sample normally inherent with this technique.