Ohno Takeshi, Shinohara Atsuko, Chiba Momoko, Hirata Takafumi
Laboratory for Planetary Sciences, Department of Earth and Planetary Sciences, Graduate School of Science and Technology, Tokyo Institute of Technology, Ohokayama 2-12-1, Meguro, Tokyo 152-8551, Japan.
Anal Sci. 2005 Apr;21(4):425-8. doi: 10.2116/analsci.21.425.
Precise 66Zn/64Zn and 68Zn/64Zn isotopic ratios of biochemical samples have been measured using multiple collector-ICP-mass spectrometry (MC-ICPMS). In order to eliminate the mass spectrometric interferences on Zn isotopes (e.g., 64Ni+ and 136Ba2+), we chemically purified the analyte using an ion chromatographic technique. The resulting precisions of the 66Zn/64Zn and 68Zn/64Zn ratio measurements were 0.05/1000 and 0.10/1000 (2SD), respectively, which were enough to detect the isotopic variation of Zn in nature. Red blood cell (RBC) samples were collected from five volunteers (four males and one female), including a series of 12 RBC samples from one person through monthly-based sampling over a year. These were analyzed to test possible seasonal changes and variations in 66Zn/64Zn and 68Zn/64Zn ratios among the individuals. The 66Zn/64Zn and 68Zn/64Zn ratios for a series of 12 RBC samples collected over a year were 0.43/1000 and 0.83/1000 higher than the values of highly purified Zn metal (JMC Zn), and no seasonal change could be found. The 66Zn/64Zn and 68Zn/64Zn ratios for RBC samples collected from five volunteers did not vary significantly. In order to investigate Zn isotopic heterogeneity in a human body, Zn isotopic ratios of a hair sample collected from one of the volunteers was also analyzed. The 66Zn/64Zn and 68Zn/64Zn ratios for the hair sample were 0.59/1000 and 1.14/1000 lower than the mean value of RBC samples. This result demonstrates that detectable isotopic fractionation occurs in the human body. The data obtained here suggest that the isotopic ratios of trace metals could provide new information about transportation of metal elements in vivo.
已使用多接收电感耦合等离子体质谱仪（MC-ICPMS）测量了生化样品精确的66Zn/64Zn和68Zn/64Zn同位素比值。为消除对锌同位素的质谱干扰（例如64Ni+和136Ba2+），我们采用离子色谱技术对分析物进行了化学纯化。66Zn/64Zn和68Zn/64Zn比值测量的最终精度分别为0.05/1000和0.10/1000（2SD），足以检测自然界中锌的同位素变化。从五名志愿者（四名男性和一名女性）采集了红细胞（RBC）样本，其中包括通过一年每月采样从一人采集的一系列12个RBC样本。对这些样本进行分析，以测试个体之间66Zn/64Zn和68Zn/64Zn比值可能的季节性变化和差异。一年中采集的一系列12个RBC样本的66Zn/64Zn和68Zn/64Zn比值分别比高纯度锌金属（JMC Zn）的值高0.43/1000和0.83/1000，未发现季节性变化。从五名志愿者采集的RBC样本的66Zn/64Zn和68Zn/64Zn比值没有显著变化。为研究人体中锌同位素的非均质性，还分析了从一名志愿者采集的头发样本的锌同位素比值。该头发样本的66Zn/64Zn和68Zn/64Zn比值分别比RBC样本的平均值低0.59/1000和1.14/1000。这一结果表明人体中发生了可检测到的同位素分馏。此处获得的数据表明，痕量金属的同位素比值可为体内金属元素的运输提供新信息。
