Discipline C: Radiochemistry, Analytical Track 2: Radiochemistry Capacity/Capability Development

该合作协议的资金将1）保留公共卫生实验室的就业机会 科学家须履行所需职责，对食物样本及基质进行辐射监察 食品中伽马发射器的扩展，2）派遣一名工作人员参加FDA年度LFFM面对面会议 会议，3）用40%效率的探测器替换最近损坏的25% HPGe探测器，以及4）支付 现场评估，以获得ISO 17025：2017认证。 VDH放射化学实验室将通过测试至少25名人类或动物来加强食品防御 每年对食品进行伽马放射性核素污染检查，包括Cs-134、Cs-137和I-131。 我们将每年分析不同的高风险样本类型（矩阵）。我们建议使用该方法 目前由温彻斯特工程和分析中心（WEAC）使用， 用高纯锗光谱法测定食品中的放射性核素我们将执行2级 在我们实验室的果汁验证此方法。将执行矩阵扩展确认 作为FERN方法确认后的2级确认，使用一个或多个新矩阵来源 指南这包括对两个加标水平和一个基质空白的分析，每个加标水平重复3次。 方法质量目标包括DIL的1 sigma不确定度为10%或更低， 至少1/2的DIL的可检测活性浓度（MDC）。第二类的可能性 误差将减至最低，需要进一步分析的样品将很容易识别。虽然VDHL 不基于MDC做出检测决策，我们发现给出一些关于 预期的样品特异性检测能力。检测决定将基于每种分析物的 与临界水平（Lc）的关系，临界水平（Lc）是基于净信号的分布计算的 在零假设下将选择样本量、几何结构和计数时间，以确保方法 质量目标得到满足。 将根据以下标准制定Cs-134、Cs-137和I-131的最低可定量浓度（MQC）： 伽马发射器方法开发跟踪的确认数据。计算的MQC为 相对标准偏差为1/10。

The funding from this cooperative agreement will 1) retain employment of a Public Health Laboratory Scientist to perform the duties necessary to conduct radiological surveillance of food samples and matrix extensions for gamma emitters in food, 2) send a staff member to the annual FDA LFFM face-to-face meeting, 3) replace a recently broken 25% HPGe detector with a 40% efficiency detector, and 4) pay for the on-site assessment to achieve ISO 17025:2017 accreditation. The VDH Radiochemistry Laboratory will enhance food defense by testing at least 25 human or animal foods annually for contamination by gamma emitting radionuclides, including Cs-134, Cs-137, and I-131. We will analyze different high-risk sample types (matrices) each year. We propose to use the method currently used by the Winchester Engineering and Analytical Center (WEAC), Determination of Gamma- Ray Emitting Radionuclides in Foods by High-Purity Germanium Spectrometry. We will perform a level 2 validation of this method in our laboratory for fruit juice. Matrix extension validations will be performed as level 2 validations with one or more sources of the new matrix, following the FERN Method Validation Guidelines. This includes analysis of two spike levels and one matrix blank, each with 3 replicates. Method quality objectives include a 1 sigma uncertainty of 10% or less at the DIL, and a minimum detectable activity concentration (MDC) of at least ½ of the DIL. In this way, the possibility of Type II errors will be minimized, and samples needing further analysis will be easily identified. While the VDHL does not make detection decisions based on the MDC, we find it useful to give some idea of the expected sample-specific detection capability. Detection decisions will be based on each analyte’s relationship to the critical level (Lc), which is calculated on the basis of the distribution of the net signal under the null hypothesis. Sample size, geometry, and count time will be selected to ensure the method quality objectives are met. A minimum quantifiable concentration (MQC) will be developed for Cs-134, Cs-137, and I-131 based on the validation data from the Gamma Emitters Method Development track. The calculated MQC will be that which gives a relative standard deviation of 1/10.