Preparation and Certification of A Titanium Isotopic Standard Solution
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摘要: 钛同位素组成可用于地球化学和宇宙化学研究中，但目前国内外缺乏钛同位素标准物质。为了满足地质样品钛同位素分析的需要，本文研制了钛同位素标准溶液，报道了钛同位素标准溶液的研制过程和定值结果，包括标准溶液的选择、均匀性和稳定性检验、定值分析及测定数据的统计性检验等。通过初步测定，确定美国Alfa公司生产的Ti单元素溶液作为备选Ti同位素标准溶液。将备选标准溶液分装成150瓶，随机抽取15瓶进行均匀性检验，测试结果的F值均小于临界值，表明备选标准溶液的Ti同位素组成均匀。通过30个月的稳定性检验，标准溶液的特征量值变化在不确定度范围内。采用独家和多家实验室相结合的方法进行定值，标准溶液的特征量值及不确定度推荐为：δ50Ti=-2.23‰±0.14‰，δ49Ti=-1.67‰±0.09‰，δ48Ti=-1.13‰±0.06‰，δ47Ti=-0.57‰±0.05‰。研制的标准溶液可用于钛同位素分析时校正仪器和验证质谱分析过程，有利于不同实验室的测试数据之间的对比和应用。Abstract: Titanium isotopic compositions have been used to elucidate geochemical and cosmochemical processes. Until now, no Ti isotopic reference material has been reported worldwide, which imposes restriction upon analytical method establishment and laboratory quality control. In this paper, a newly prepared Ti isotopic standard solution is introduced. Ti element standard solution offered by the Alfa Company from U.S.A. was chosen as the starting material, based on the comparison of Ti isotopic measurement results of 3 commercially available Ti element standard solutions. The preparation of the new standard solution was strictly followed using the stipulation on reference material of the metrological technical standard of state, including homogeneity and stability tests, and certification analyses. 150 bottles of the solution were prepared, among which 15 bottles were selected randomly for homogeneity test and no detectable heterogeneity was found by F test. The stability inspection through 30 months indicated no significant changes on δTi values. The certified values and uncertainty at the 95% confidence level were shown to be: δ50Ti=-2.23‰±0.14‰, δ49Ti=-1.67‰±0.09‰,δ48Ti=-1.13‰±0.06‰ andδ47Ti=-0.57‰±0.05‰. This newly certified standard solution can be used to calibrate instruments and verify analytical quality in Ti isotope measurements, and compare inter-laboratory data.
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Key words:
- titanium isotopes /
- standard solution /
- certified value
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表 1 三种溶液钛同位素组成初步测定结果
Table 1. Preliminary results of Ti isotope composition for three different solutions
Ti单元素溶液 δ50Ti δ49Ti δ48Ti δ47Ti Ti-1
(北京有色金属研究总院)-2.11 -1.59 -1.06 -0.54 Ti-2
(美国Alfa公司)-2.24 -1.69 -1.13 -0.55 Ti-3
(美国High-Purity Standards公司)-1.44 -1.10 -0.74 -0.37 
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表 2 均匀性检验方差分析结果
Table 2. Variance analysis for homogeneity inspection of reference sample
δ Q2 ν2 s22 Q1 ν1 s12 F Fα(ν1,ν2) δ50Ti 0.118 30 0.00392 0.069 14 0.00496 1.26 2.02 δ49Ti 0.070 0.00234 0.035 0.00253 1.08 δ48Ti 0.044 0.00145 0.018 0.00130 0.89 δ47Ti 0.041 0.00135 0.012 0.00082 0.61
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表 3 标准溶液在30个月内特性量值的测定数据
Table 3. Measurement data of δTi in 30 months
时长/月 δ50Ti/‰ δ49Ti/‰ δ48Ti/‰ δ47Ti/‰ 4 -2.20 -1.67 -1.11 -0.54 8 -2.24 -1.69 -1.13 -0.57 12 -2.18 -1.65 -1.11 -0.56 20 -2.19 -1.66 -1.11 -0.56 22 -2.21 -1.67 -1.12 -0.56 30 -2.19 -1.65 -1.11 -0.56
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表 4 标准溶液稳定性检验结果
Table 4. The stability test of reference sample
特征量值 b1 b0 s s(b1) t0.95,4×s(b1) st δ50Ti 0.000949 -2.22 0.02293 0.001056 0.00293 0.032 δ49Ti 0.000777 -1.68 0.01297 0.000597 0.00166 0.018 δ48Ti 0.000299 -1.12 0.00946 0.000436 0.00121 0.013 δ47Ti 0.000307 -0.56 0.01424 0.000655 0.00182 0.020
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表 5 钛同位素标准溶液的多次测量数据(单一实验室)
Table 5. Multiple measurement data of Ti isotope composition for reference samples (unique laboratory)
序号 编号 第1次测定 第2次测定 第3次测定 平均值 δ50Ti δ49Ti δ48Ti δ47Ti δ50Ti δ49Ti δ48Ti δ47Ti δ50Ti δ49Ti δ48Ti δ47Ti δ50Ti δ49Ti δ48Ti δ47Ti 1 2 -2.14 -1.66 -1.11 -0.59 -2.15 -1.62 -1.12 -0.62 -2.12 -1.62 -1.05 -0.50 -2.14 -1.63 -1.09 -0.57 2 9 -2.27 -1.71 -1.18 -0.60 -2.32 -1.73 -1.10 -0.53 -2.12 -1.62 -1.05 -0.54 -2.24 -1.69 -1.11 -0.56 3 13 -2.27 -1.70 -1.16 -0.60 -2.18 -1.65 -1.11 -0.58 -2.20 -1.72 -1.09 -0.51 -2.22 -1.69 -1.12 -0.56 4 15 -2.25 -1.69 -1.12 -0.54 -2.19 -1.68 -1.13 -0.60 -2.24 -1.68 -1.14 -0.57 -2.23 -1.68 -1.13 -0.57 5 32 -2.25 -1.68 -1.12 -0.58 -2.16 -1.61 -1.11 -0.60 -2.30 -1.70 -1.15 -0.63 -2.24 -1.66 -1.13 -0.60 6 42 -2.29 -1.76 -1.18 -0.60 -2.26 -1.72 -1.16 -0.62 -2.28 -1.77 -1.16 -0.62 -2.28 -1.75 -1.17 -0.61 7 44 -2.20 -1.66 -1.11 -0.56 -2.26 -1.67 -1.15 -0.57 -2.29 -1.75 -1.16 -0.63 -2.25 -1.69 -1.14 -0.59 8 51 -2.25 -1.70 -1.16 -0.56 -2.27 -1.70 -1.17 -0.62 -2.22 -1.70 -1.13 -0.58 -2.25 -1.70 -1.15 -0.59 9 54 -2.31 -1.77 -1.18 -0.58 -2.19 -1.61 -1.10 -0.58 -2.27 -1.66 -1.15 -0.54 -2.26 -1.68 -1.14 -0.57 10 57 -2.24 -1.66 -1.12 -0.56 -2.20 -1.68 -1.11 -0.55 -2.34 -1.70 -1.19 -0.63 -2.26 -1.68 -1.14 -0.58 11 60 -2.29 -1.74 -1.18 -0.61 -2.16 -1.63 -1.10 -0.54 -2.32 -1.78 -1.20 -0.62 -2.26 -1.72 -1.16 -0.59 12 66 -2.29 -1.76 -1.18 -0.58 -2.23 -1.66 -1.10 -0.52 -2.36 -1.71 -1.14 -0.57 -2.29 -1.71 -1.14 -0.56 13 79 -2.35 -1.76 -1.19 -0.64 -2.21 -1.70 -1.11 -0.54 -2.37 -1.75 -1.17 -0.59 -2.31 -1.74 -1.16 -0.59 14 86 -2.30 -1.74 -1.18 -0.58 -2.25 -1.71 -1.16 -0.58 -2.19 -1.65 -1.09 -0.60 -2.25 -1.70 -1.14 -0.59 15 96 -2.32 -1.71 -1.18 -0.61 -2.35 -1.80 -1.19 -0.60 -2.21 -1.65 -1.13 -0.56 -2.29 -1.72 -1.17 -0.59
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表 6 钛同位素标准溶液的定值分析数据
Table 6. The analytical data of Ti isotope composition for reference samples
实验室
编号编号 第1次测定 第2次测定 第3次测定 平均值 δ50Ti δ49Ti δ48Ti δ47Ti δ50Ti δ49Ti δ48Ti δ47Ti δ50Ti δ49Ti δ48Ti δ47Ti δ50Ti δ49Ti δ48Ti δ47Ti ① 2 -2.25 -1.68 -1.12 -0.58 -2.16 -1.61 -1.11 -0.60 -2.30 -1.70 -1.15 -0.63 -2.24 -1.66 -1.13 -0.60 42 -2.29 -1.76 -1.18 -0.6 -2.26 -1.72 -1.16 -0.62 -2.28 -1.77 -1.16 -0.62 -2.28 -1.75 -1.17 -0.61 66 -2.20 -1.68 -1.11 -0.56 -2.26 -1.67 -1.15 -0.57 -2.29 -1.75 -1.16 -0.61 -2.25 -1.70 -1.14 -0.58 ② 15 -2.23 -1.64 -1.15 -0.53 -1.97 -1.51 -1.07 -0.52 -2.29 -1.71 -1.17 -0.56 -2.16 -1.62 -1.13 -0.53 54 -2.05 -1.61 -1.09 -0.51 -2.07 -1.57 -1.11 -0.53 -2.24 -1.63 -1.16 -0.58 -2.12 -1.60 -1.12 -0.54 86 -2.24 -1.70 -1.13 -0.58 -2.08 -1.63 -1.08 -0.55 -2.35 -1.75 -1.21 -0.61 -2.22 -1.70 -1.14 -0.58 ③-1 32 -2.32 -1.75 -1.15 -0.58 -2.44 -1.80 -1.20 -0.63 -2.25 -1.65 -1.14 -0.55 -2.33 -1.73 -1.17 -0.59 44 -2.44 -1.81 -1.22 -0.61 -2.32 -1.71 -1.15 -0.57 -2.41 -1.75 -1.20 -0.61 -2.39 -1.76 -1.19 -0.59 79 -2.47 -1.84 -1.23 -0.64 -2.27 -1.62 -1.10 -0.55 -2.46 -1.81 -1.22 -0.61 -2.40 -1.76 -1.18 -0.60 ③-2 9 -2.13 -1.6 -1.06 -0.54 -1.99 -1.52 -0.99 -0.49 -2.32 -1.76 -1.18 -0.61 -2.15 -1.63 -1.08 -0.55 57 -2.20 -1.63 -1.11 -0.63 -1.94 -1.44 -0.98 -0.52 -2.22 -1.64 -1.09 -0.56 -2.12 -1.57 -1.06 -0.57 96 -2.07 -1.56 -1.05 -0.53 -2.10 -1.56 -1.05 -0.54 -2.26 -1.65 -1.09 -0.53 -2.14 -1.59 -1.06 -0.53
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表 7 标准物质定值数据的不确定度
Table 7. Certified values and uncertainty from certified values for reference samples
定值实验室 项目 δ50Ti/‰ δ49Ti/‰ δ48Ti/‰ δ47Ti/‰ 单一实验室 标准值( 
)-2.26 -1.70 -1.14 -0.58 标准偏差(s) 0.027 0.024 0.017 0.017 不确定度(Uchar) 0.03 0.02 0.024 0.014 测量组数(N) 14 14 14 14 多家实验室 标准值( )-2.23 -1.67 -1.13 -0.57 标准偏差(s) 0.101 0.069 0.045 0.029 不确定度(Uchar) 0.053 0.034 0.02 0.02 测量组数(N) 12 12 12 12
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表 8 标准溶液的不确定度
Table 8. The uncertainty of reference samples
不确定度 δ50Ti/‰ δ49Ti/‰ δ48Ti/‰ δ47Ti/‰ Ubb 0.032 0.014 0.011 0.0084 Ults 0.032 0.018 0.013 0.020 Uchar 0.0534 0.0340 0.0239 0.0137 UCRM 0.070 0.041 0.029 0.026 UC 0.140 0.082 0.058 0.051
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