The sample in tin leaf clad is put into a graphite crucible with a cap. Firstly, the sample is decomposed by heat at about 660 ℃, and the multiform oxygen in the sample is reserved in tin-lithium alloy by the Li2O form. 将锡箔包裹的试样投入带盖石墨坩埚中,第一步先在脉冲电弧炉中于660℃左右热分解,试样中各种形式的氧以Li2O形式保留在生成的锡锂合金中;