直流电弧全谱直读原子发射光谱法(DC-Arc-AES)测定地球化学样品中痕量硼、钼、银、锡、铅的方法研究

Study on the Method for the Determination of Trace Boron,Molybdenum,Silver,Tin and Lead in Geochemical Samples by Direct Current Arc Full Spectrum Direct Reading Atomic Emission Spectroscopy(DC-Arc-AES)

建立了直流电弧全谱直读原子发射光谱法（DC-Arc-AES）测定地球化学样品中痕量硼、钼、银、锡、铅的分析方法。所使用直流电弧全谱直读原子发射光谱仪采用大面积固态检测器,具有全谱直读功能,并能实时背景校正。通过研究提出了新的电极和新的缓冲剂配方,方法采用内标法,以Ge元素作内标元素,同时选择了合适的分析线对。电流程序研究中设置多级电流,每级电流设置不同保持时间,升电流时选择连续升电流方式,可以有效消除试样的飞溅。以氩气为保护气消除CN带的产生并减少光谱背景,选择氩气流量为3.5L·min-1。作各元素的蒸发曲线,得出各元素的蒸发行为基本一致,同时结合摄谱时间对各元素强度和背景的影响,得出最佳的设谱时间为35s。方法选择国家一级地球化学标准物质作为标准系列,标准系列中包括了不同性质、不同含量的标准物质,满足地球化学样品中痕量硼、钼、银、锡、铅的测定。在优化的实验条件下,方法检出限为：B：1.1μg·g-1,Mo：0.09μg·g-1,Ag：0.01μg·g-1,Sn：0.41μg·g-1,Pb：0.56μg·g-1,精密度为（RSD,n=12）：B：4.57%~7.63%,Mo：5.14%~7.75%,Ag：5.48%~12.30%,Sn：3.97%~10.46%,Pb：4.26%~9.21%,准确度通过国家一级地球化学标准物质验证,结果与标准值相符。本方法简便、快速,是测定地球化学样品中痕量硼、钼、银、锡、铅的一种先进的分析方法,具有一定的实用性。

The method for the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples by direct current arc full spectrum direct reading atomic emission spectroscopy （DC-Arc-AES） was established. Direct current arc full spectrum direct reading atomic emission spectrometer with a large area of solid-state detectors has functions of full spectrum di- rect reading and real-time background correction. The new electrodes and new buffer recipe were proposed in this paper, and have applied for national patent. Suitable analytical line pairs, back ground correcting points of elements and the internal stand- ard method were selected, and Ge was used as internal standard. Multistage currents were selected in the research on current program, and each current set different holding time to ensure that each element has a good signal to noise ratio. Continuous ris- ing current mode selected can effectively eliminate the splash of the sample. Argon as shielding gas can eliminate CN band gener- ating and reduce spectral background, also plays a role in stabilizing the arc, and argon flow 3.5 L ~ min-1 was selected. Evapo- ration curve of each element was made, and it was concluded that the evaporation behavior of each element is consistent, and combined with the effects of different spectrographic times on the intensity and background, the spectrographic time of 35s was selected. In this paper, national standards substances were selected as a standard series, and the standard series includes differ- ent nature and different content of standard substances which meet the determination of trace boron, molybdenum, silver, tin and lead in geochemical samples. In the optimum experimental conditions, the detection limits for B, Mo, Ag, Sn and Pb are 1.1, 0. 09, 0. 01, 0. 41, and 0.56 μg · g-1 respectively, and the precisions （RSD, n=12） for B, Mo, Ag, Sn and Pb are 4.57~7.63%, 5.14~7.75%, 5.48%~12.30%, 3.97%~10. 46%, and 4. 26%~9.21% respectively. The analytical ac- curacy was validated by national standards and the results are in agreement with certified values. The method is simple, rapid, is an advanced analytical method for the determination of trace amounts of geochemical samples＇ boron, molybdenum, silver, tin and lead, and has a certain practicality.