供应美国NIST可追溯碳酸锂标准物质SRM 924a
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Purpose: This Standard Reference Material (SRM) is intended for use as a chemical of known purity in the calibration and standardization of procedures and for the routine critical evaluation of the daily working standards used in these procedures.
Description: A unit of SRM 924a consists of a single glass bottle containing 30 g of material. 可追溯碳酸锂标准物质
Certified Value: A NIST certified value is a value for which NIST has the highest confidence in its accuracy in that all known or suspected sources of bias have been investigated or taken into account [1]. The measurand is the total mass fraction for lithium carbonate. Metrological traceability is to the International System of Units (SI) derived unit for mass fraction (expressed as a percent). This certified value is calculated from the results of independent coulometric assays. The stated uncertainty is the expanded uncertainty, U, expressed at a level of confidence of approximately 95 % and calculated as U = kuc, where uc is the combined standard uncertainty calculated according to the ISO/JCGM Guide [2]. The value of uc is intended to represent, at the level of one standard deviation, the combined effects of material variability as well as random and systematic components of uncertainty. The value of the coverage factor, k, is 2. The relative molecular mass for lithium carbonate used in the calculations is 73.8915 and is based on the lithium isotopic abundance as determined by mass spectrometry in the SRM material. 美国NIST可追溯
本标准参考物质（SRM）旨在用作程序校准和标准化中已知纯度的化学品，并用于对这些程序中使用的日常工作标准进行常规关键评估。
SRM 924a的一个单元由一个装有30克材料的玻璃瓶组成。
NIST认证值是指NIST对其准确性具有最高信心的值，因为所有已知或怀疑的偏差来源都已被调查或考虑[1]。被测物是碳酸锂的总质量分数。计量可追溯性是指国际单位制（SI）衍生的质量分数单位（以百分比表示）。该认证值是根据独立电量测定的结果计算得出的。所述不确定度是扩展不确定度U，以大约95%的置信水平表示，并计算为U=kuc，其中uc是根据ISO/JCGM指南[2]计算的组合标准不确定度。uc的值旨在在一个标准偏差的水平上表示材料可变性以及不确定性的随机和系统成分的综合影响。覆盖因子k的值为2。计算中使用的碳酸锂的相对分子质量为73.8915，基于SRM材料中通过质谱测定的锂同位素丰度。
SRM 924a – Lithium Carbonate
产品名称 Description: Lithium Carbonate
产品批号 Lot: N/A
产品有效期 Expiration Date: 5/1/2022
产品包装 Unit of Issue: 30 g
销售状态 Status: Now Selling
COA日期 Certificate Date: 2/9/2016
运输条件 Perishable: No
是否危险品 Hazardous Material: No 运输方式 Material Hazard Class: Not Hazardous to Ship