水浴加热密闭溶样石墨炉原子吸收光谱法测定化探样品中的痕量金

Determination of Trace Gold in Geochemical Exploration Samples by GFAAS with Water Bath Heating Sealed Digestion

以王水、氟化钾、Fe3＋溶液为溶剂，对化探样品进行水浴加热分解1.5 h，经泡沫塑料吸附后，于90℃以上硫脲溶液中解吸20 min，然后采用石墨炉原子吸收光谱仪测定其中的金含量。对仪器分析条件进行了优化。金的质量分数在0.1～100.0 ng／g范围内与吸光度呈良好的线性，线性相关系数r2=0.9993，检出限为0.100 ng／g。该方法对金标准物质测定结果的相对标准偏差为5.96%～9.25%（n=12），对国家一级标准物质进行分析，测定结果与标准值相符合。该方法满足1∶50000化探样品中痕量金的分析要求。

Geochemical exploration sample was treated in the conditions as follows：aqua regia, potassium fluoride and Fe3＋solution as the solvent, water bath heating decomposition 1.5 h and disengagement above 9 0℃ for 20 minutes. Then content of gold in sample was determined by graphite furnace atomic absorption method.Instrument parameters were optimized. The mass fraction of gold was linear with absorbance in the range of 0.1–100 ng/g with the correlation coefficient of r2=0.999 3,the detection limit of the method for gold was 0.100 ng/g. The relative standard deviation of detection results of gold reference material was 5.96%–9.25%（n=12）. The method was used to detect standard substance and results were consistent with the standard value.The method can meet the requirements of detection of trace gold in 1∶50 000 geochemical sample.