供应美国NIST-SRM 2669冷冻人体尿液中的砷标准物质
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This Standard Reference Material (SRM) is intended primarily for validating analytical methods and measurements for the determination of arsenic species in human urine. A unit of SRM 2669 consists of five pouches, each pouch containing one vial of Level I and one vial of Level II Arsenic Species in Frozen Human Urine. Each vial contains nominally 1.5 mL of urine. SRM 2669 is shipped on dry ice, and it should be stored at –80 C until use.The development of SRM 2669 was a collaboration between NIST and the Centers for Disease Control and Prevention (CDC), National Centers for Environmental Health, Division of Laboratory Sciences, (Atlanta, GA).
Certified Values: Table 1 lists the certified values and expanded uncertainties for arsenic species in SRM 2669. The structural formulas of the arsenic species are shown in the appendix. 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 certified value is the unweighted average of the values from NIST and collaborating laboratories. The expanded uncertainty is calculated as U = kuc, where uc is intended to represent, at the level of one standard deviation, the combined uncertainty due to material variability and measurement uncertainty calculated according to the method described in the ISO/JCGM Guide [2] and reference 3. The coverage factor, k, for a 95 % confidence interval, equals 2 for all certified values in Table 1. 美国NIST-SRM 2669
NIST- SRM 2669 Arsenic Species in Frozen Human Urine / 冷冻人体尿液中的砷标准物质
本标准参考物质（SRM）主要用于验证测定人类尿液中砷物种的分析方法和测量方法。SRM 2669的一个单元由五个小袋组成，每个小袋含有一小瓶冷冻人类尿液中的一级和二级砷。每个小瓶标称含有1.5毫升尿液。SRM 2669在干冰上运输，应储存在–80SRM 2669的开发是NIST与美国疾病控制与预防中心（CDC）、美国国家环境卫生中心实验室科学部（佐治亚州亚特兰大）的合作。
认证值：表1列出了SRM 2669中砷物种的认证值和扩展的不确定性。砷物种的结构式如附录所示。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源都已被调查或考虑[1]。认证值是NIST和合作实验室的未加权平均值。扩展不确定度计算为U=kuc，其中uc旨在表示在一个标准偏差的水平上，由于材料可变性引起的组合不确定度和根据ISO/JCGM指南[2]和参考文献3中描述的方法计算的测量不确定度。95%置信区间的覆盖系数k等于表1中所有认证值的2。