石墨炉原子吸收光谱法测定化探样中痕量银的方法改进

An Improved Method for Determination of Trace Silver in Geochemical Exploration Samples by Graphite Furnace Atomic Absorption Spectrometry

应用石墨炉原子吸收光谱法测定地球化学样品中的痕量银,一般采用盐酸-硝酸-氢氟酸-高氯酸电加热溶样,铱、铂为基体改进剂,以硫脲作为介质可能会导致大量铜与硫脲发生沉淀,干扰测量结果,分析流程繁琐、成本高。本文采用50%的王水水浴溶样,以湿加方式加入50 g/L硫脲基体改进剂,避免了铜在溶液中与硫脲络合,消除了干扰。方法检出限为0.01μg/g,准确度和精密度好,内外检合格率符合地质矿产行业标准。该方法简化了样品处理步骤,提高了工作效率,分析成本降低,适合批量样品的分析,且溶解样品的溶液还可继续用于氢化物发生法测定砷、汞、铋、锑等元素。

The chemical procedure of the HC1-HNO3-HF-HC104 acids system on the electric heating plate is usually used to determine trace Ag in geochemical exploration samples using the Graphite Furnace Atomic Absorption Spectrometry （GFASS） method. Ir and Pt are usually used as the matrix modifiers. However, the thiourea serving as the medium probably leads to a large amount of precipitation with Cu, which interferes with the measurement results. Also, this dissolution method is time consuming during the analysis process and costly. In this paper it is reported that sample in water bath is dissolved by 50% aqua regia. The 50 g/L thiourea matrix modifier was added as the solution, avoiding the precipitation with Cu. The detection limit was 0.01 μg/g with good accuracy and precision. The qualified rates of internal and external examination were in agreement with the standard values. This new method simplifies the processing steps, saving time and cost, and is suitable for batch samples analyses. Furthermore, the dissolved solution of the samples was applied to determine As, Hg, Bi, Sb and other elements by the hydride generation method.