供应美国NIST-SRM 2688冷冻人体尿液中的有毒元素标准物质
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This Standard Reference Material (SRM) is intended primarily for validating analytical methods and measurements for the determination of toxic elements in human urine. A unit of SRM 2668 consists of five vials of each of two levels. Each vial contains nominally 1.5 mL of urine. SRM 2668 is shipped on dry ice, and it should be stored at −70 °C until use. 美国NIST-SRM 2688
The development of SRM 2668 was a collaboration between the National Institute of Standards and Technology (NIST) and the Centers for Disease Control and Prevention (CDC), National Centers for Environmental Health, Division of Laboratory Sciences, Atlanta, GA. Certified Mass Concentration Values: Certified mass concentration values for 6 elements in Level I and 14 elements in Level II of SRM 2668 are listed in Table 1. 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]. Values were derived from the combination of results provided by NIST and collaborating laboratories. The certified values in this material are the weighted means [2‒4] of the individual sets of measurements made by NIST and collaborating laboratories. The associated expanded uncertainties include between-laboratory,within-laboratory, and inhomogeneity components of uncertainty and are provided at the 95 % level of confidence [5].
Reference Mass Concentration Values: Reference mass concentration values for 17 elements in Level I and 9 elements in Level II are provided in Table 2. Reference values are non-certified values that are the best estimate of the true values based on available data; however, the values do not meet the NIST criteria for certification [1] and are provided with associated uncertainties that may not include all sources of uncertainty. 冷冻人体尿液中的有毒元素标准物质
本标准参考物质（SRM）主要用于验证测定人体尿液中有毒元素的分析方法和测量方法。SRM 2668的一个单元由五个小瓶组成，每个小瓶有两个级别。每个小瓶标称含有1.5毫升尿液。SRM 2668在干冰上运输，使用前应储存在−70°C的温度下。
SRM 2668的开发是美国国家标准与技术研究所（NIST）与美国疾病控制与预防中心（CDC）、美国国家环境卫生中心、佐治亚州亚特兰大实验室科学部的合作。
认证质量浓度值：表1列出了SRM 2668一级6种元素和二级14种元素的认证质量浓度。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]。数值来源于NIST和合作实验室提供的结果组合。本材料中的认证值是NIST和合作实验室进行的单独测量的加权平均值[2-4]。相关的扩展不确定性包括实验室之间、实验室内和不确定性的不均匀性分量，并以95%的置信水平提供[5]。
参考质量浓度值：表2中提供了17种一级元素和9种二级元素的参考质量浓度。参考值是未经认证的值，是基于可用数据对真实值的最佳估计；然而，这些值不符合NIST认证标准[1]，并且具有相关的不确定性，可能不包括所有不确定性来源。
NIST- SRM 2688 Toxic Elements in Frozen Human Urine