供应美国NIST- SRM 1955a冷冻人血清中的同型半胱氨酸和叶酸标准物质
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This Standard Reference Material (SRM) is intended primarily for use in evaluating the accuracy of clinical procedures for the determination of homocysteine and folate (in various forms) in human serum. It is also intended for use in validating working or secondary reference materials. A unit of SRM 1955 consists of three bottles of frozen human serum, each of a different analyte concentration level. Each bottle contains 1 mL of human serum. 美国NIST- SRM 1955a
The certified concentrations and their expanded uncertainties for total homocysteine (tHCY) and 5-methyltetrahydrofolic acid (5MT) are listed in Table 1. The certified concentrations of tHCY were determined at NIST using a combination of higher-order reference measurement procedures based upon isotope dilution with gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), and liquid chromatography/tandem mass spectrometry (LC/MS/MS) [1–3]. The certified concentrations for 5MT were determined by a combination of reference measurement procedures based upon isotope dilution LC/MS/MS performed at NIST [3,4] and the Centers for Disease Control and Prevention (CDC) [5]. The methods performed at NIST for tHCY and 5MT are recognized as approved higher order reference measurement procedures by the Joint Committee on Traceability in Laboratory Medicine (JCTLM) [6]. The certified concentrations apply only to serum thawed to room temperature, 20 °C to 25 °C (see “Instructions for Storage, Stability, and Use”). 冷冻人血清中的同型半胱氨酸和叶酸标准物质
本标准参考物质（SRM）主要用于评估测定人体血清中同型半胱氨酸和叶酸（各种形式）的临床程序的准确性。它也用于验证工作或二次参考材料。SRM 1955的一个单元由三瓶冷冻人血清组成，每瓶都具有不同的分析物浓度水平。每个瓶子含有1毫升人体血清。
表1列出了总同型半胱氨酸（tHCY）和5-甲基四氢叶酸（5MT）的认证浓度及其扩展的不确定度。NIST使用基于同位素稀释的高阶参考测量程序与气相色谱/质谱法（GC/MS）、液相色谱/色谱法（LC/MS）和液相色谱-串联质谱法（LC/MS/MS）的组合来确定tHCY的认证浓度[1-3]。5MT的认证浓度是根据NIST[3，4]和美国疾病控制与预防中心[5]进行的同位素稀释LC/MS/MS，通过参考测量程序的组合确定的。NIST针对tHCY和5MT执行的方法被实验室医学可追溯性联合委员会（JCTLM）认可为批准的高阶参考测量程序[6]。认证浓度仅适用于解冻至室温20°C至25°C的血清（见“储存、稳定性和使用说明”）。