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

这项合作协议提供的资金将1)保留公共卫生实验室的工作

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.