Coplen Tyler B, Qi Haiping
US Geological Survey, Reston, Virginia, USA.
Isotopes Environ Health Stud. 2009 Jun;45(2):126-34. doi: 10.1080/10256010902871952.
New isotope laboratories can achieve the goal of reporting the same isotopic composition within analytical uncertainty for the same material analysed decades apart by (1) writing their own acceptance testing procedures and putting them into their mass spectrometric or laser-based isotope-ratio equipment procurement contract, (2) requiring a manufacturer to demonstrate acceptable performance using all sample ports provided with the instrumentation, (3) for each medium to be analysed, prepare two local reference materials substantially different in isotopic composition to encompass the range in isotopic composition expected in the laboratory and calibrated them with isotopic reference materials available from the International Atomic Energy Agency (IAEA) or the US National Institute of Standards and Technology (NIST), (4) using the optimum storage containers (for water samples, sealing in glass ampoules that are sterilised after sealing is satisfactory), (5) interspersing among sample unknowns local laboratory isotopic reference materials daily (internationally distributed isotopic reference materials can be ordered at three-year intervals, and can be used for elemental analyser analyses and other analyses that consume less than 1 mg of material) - this process applies to H, C, N, O, and S isotope ratios, (6) calculating isotopic compositions of unknowns by normalising isotopic data to that of local reference materials, which have been calibrated to internationally distributed isotopic reference materials, (7) reporting results on scales normalised to internationally distributed isotopic reference materials (where they are available) and providing to sample submitters the isotopic compositions of internationally distributed isotopic reference materials of the same substance had they been analysed with unknowns, (8) providing an audit trail in the laboratory for analytical results - this trail commonly will be in electronic format and might include a laboratory information management system, (9) making at regular intervals a complete backup of laboratory analytical data (both of samples logged into the laboratory and of mass spectrometric analyses), being sure to store one copy of this backup offsite, and (10) participating in interlaboratory comparison exercises sponsored by the IAEA and other agencies at regular intervals.
对于间隔数十年分析的同一种材料，在分析不确定度范围内报告相同的同位素组成。方法如下：(1)编写自己的验收测试程序，并将其纳入质谱仪或基于激光的同位素比率设备采购合同；(2)要求制造商使用仪器配备的所有样品端口展示可接受的性能；(3)对于每种待分析介质，制备两种同位素组成差异较大的本地参考物质，以涵盖实验室预期的同位素组成范围，并用国际原子能机构（IAEA）或美国国家标准与技术研究院（NIST）提供的同位素参考物质对其进行校准；(4)使用最佳储存容器（对于水样，密封在密封后经过消毒的玻璃安瓿中）；(5)每天在未知样品中穿插本地实验室同位素参考物质（国际分发的同位素参考物质可以每三年订购一次，可用于元素分析仪分析和其他消耗材料少于1毫克的分析）——此过程适用于氢、碳、氮、氧和硫的同位素比率；(6)通过将同位素数据归一化至已校准至国际分发的同位素参考物质的本地参考物质的数据，计算未知物的同位素组成；(7)在归一化至国际分发的同位素参考物质（若有）的尺度上报告结果，并向样品提交者提供如果与未知物一同分析该同一种物质的国际分发同位素参考物质的同位素组成；(8)在实验室为分析结果提供审核跟踪——此跟踪通常为电子格式，可能包括实验室信息管理系统；(9)定期对实验室分析数据（包括录入实验室的样品数据和质谱分析数据）进行完整备份，确保在异地存储一份备份；(10)定期参加由国际原子能机构和其他机构主办的实验室间比对活动。
