高分辨连续光源原子吸收光谱法测定铀铌铅多金属矿中痕量银

铀铌铅多金属矿组成成分复杂,准确有效的测定其中的痕量银,有利于银的回收利用。采用HCl-HNO₃-HF-HClO₄处理铀铌铅多金属矿样品,以HCl(1+4)-2g/L酒石酸为测定介质,以λ_Ag=328.068nm为分析谱线,建立了高分辨连续光源原子吸收光谱法(HR-CS-AAS)测定铀铌铅多金属矿样品中痕量银的新方法。对仪器参数进行了优化,确定采用迭代基线校正(IBC)背景校正方式,CCD检测器有效像素点选择5个;由银的平均吸收光谱图和吸光度-波长-时间三维吸收光谱图可知,银的CCD检测器分辨率为0.0020nm/pixel,λ_Ag=328.068nm在327.86~328.27nm范围内没有受到溶液中其他共存元素的谱线干扰。在优化的实验条件下,银的吸光度与其质量浓度在0.40~1.60μg/mL范围内运用二次方程最小二乘法拟合校准曲线,相关系数为0.9999,特征浓度为0.0148μg/mL,方法检出限为0.0013μg/mL。将HR-CS-AAS测定样品中银的参数与空心阴极灯原子吸收光谱法(HCL-AAS)相比,其检出限更低,特征浓度更低,标准溶液系列的吸光度更高。按照实验方法对铀铌铅多金属矿样品中的银进行测定,结果与电感耦合等离子体质谱法基本一致,相对标准偏差(RSD,n=9)为0.63%~3.3%。按实验方法在铀铌铅多金属矿样品中加入银标准溶液进行加标回收试验,回收率为97%~104%,满足国家地质矿产行业标准DZ/T 0130—2006的要求。

Determination of trace silver in uranium-niobium-leadpolymetallic ore by high resolution continuumsource flame atomic absorption spectrometry

The composition of uranium-niobium-lead polymetallic ore was complex. It was beneficial to recycle of silver for accurate and effective determination of trace silver in uranium-niobium-lead polymetallic ore. After the samples were dissolved by HCl-HNO₃-HF-HClO₄, a determination method of silver was established by high resolution continuum source flame atomic absorption spectrometry (HR-CS-AAS) with HCl(1+4) and 2g/L tartaric acid as test medium and λ_Ag=328.068nm as the analytical line. The instrumental parameters were optimized. The background was corrected by iterative baseline correction (IBC) method. 5 pixels were used as the effective pixel points for the CCD detector. According to the average absorption spectrum of silver and the three-dimensional absorption spectrum of absorbance-wavelength-time, the resolution of CCD detector for silver was 0.0020nm/pixel. The analytical line of λ_Ag=328.068nm was not interfered by the spectral lines of other coexisting elements in the solution in the range of 327.86-328.27nm. Under the optimized experimental conditions, the calibration curve was fitted with the absorbance of silver and its corresponding concentration in the range of 0.40-1.60μg/mL by least square method of quadratic equation, the correlation coefficient was 0.9999. The characteristic concentration was 0.0148μg/mL, and the detection limit of method was 0.0013μg/mL. Compared with the hollow cathode lamp atomic absorption spectrometry (HCL-AAS), the parameters for determination of silver in the sample by HR-CS-AAS have lower detection limit, lower characteristic concentration, and higher absorbance for the standard solution series. The uranium-niobium-lead polymetallic ore samples were determined according to the experimental method. The results were basically consistent with those by inductively coupled plasma mass spectrometry, and the relative standard deviations (RSDs, n=9) were between 0.63% and 3.3%. The spiked recovery test was conducted by addition of silver standard solution to the uranium-niobium-lead polymetallic ore samples according to the experimental method. The recoveries were between 97% and 104%, which met the requirements of the national geological and mineral industry standard DZ/T 0130-2006.