二苯硫脲泡塑富集-原子吸收光谱法连续测定化探样品中金和银

摘要

The results of analysis by the traditional methods of gold and silver determination in geochemical samples by emission spectrometry, chemical spectroscopy or atomic absorption spectrometry concentrated by load foam, is unstable and inefficient. As reported in this paper, the samples have been decomposed by 50% aqua regia. Au and Ag were concentrated by loaded diphenylthiourea foam which was cleaned with deionized water. The trace amounts of Au and Ag were then simultaneously measured by using Graphite Furnace Atomic Absorption Spectrophotometry (GFAAS) and Flame Atomic Absorption Spectrophotometry ( FAAS) . The experimental conditions were optimized by using a concentration of diphenylthiourea of 7 mg/mL, hydrochloric acid concentration of 8% , oscillation time of 25 min and absorption temperature oi 20X.. The recoveries of Au and Ag were 97.9% and 98.8% respectively. After the improvement, the detection limits of Au and Ag were 0. 25 ng/g and 0.038 |xg/g respectively, relative errors were 2.0% -14.0% and7.7% -13.3% (n=9), RSDs were 3. 1% -12.4% and 5. 1% -13,2% respectively (n =9) by using this method. The method has been verified by determination of national first level standard material with satisfactory results. This method resolves simultaneous determination of Au and Ag in one solution. Compared with determination of Ag by Emission Spectrometry and determination of Au by Graphite Furnace Atomic Absorption Spectrometry, this method has the advantages of large sampling of 10 g to increase the representativeness, simple operation, low cost and labor, high accuracy and precision, which was able to efficiently test trace Au and Ag.%传统的发射光谱、化学光谱、泡塑富集分离-原子吸收光谱法测定化探样品中的金和银,分析结果不稳定,效率低.本研究提出用50％的王水分解化探样品,负载二苯硫脲泡塑吸附金银,石墨炉和火焰原子吸收光谱法对金和银进行联合测定.在二苯硫脲浓度、吸附酸度、吸附温度、振荡时间等优化的实验条件下,金和银的回收率分别达到97.9％和98.8％,检出限为0.25 ng/g和0.038 μg/g,准确度(RE,n=9)为2.0％ ～14.0％和7.7％ ～13.3％,精密度(RSD,n=9)为3.1％ ～12.4％和5.1％ ～13.2％.经国家标准物质分析验证,测定值与标准值基本相符.该方法实现了在同一份溶液中同时测定金和银,与现行的石墨炉原子吸收光谱测定金、发射光谱测定银的方法相比,称样量达到10 g,样品的代表性显著增加,提高了准确度和精密度,简化了金银分析的程序,化学试剂用量少,分析成本低.