NIST currently coordinates several quality assurance programs that participants use for various purposes, including compliance with federal regulations. Participation in a quality assurance program in conjunction with the use of SRMs has been shown to improve the comparability and precision of data over time, as shown below.
BIOSCIENCE AND HEALTH
NIST has established a Dietary Supplement Quality Assurance Program (DSQAP) in collaboration with the National Institutes of Health (NIH) Office of Dietary Supplements (ODS). Participants measure concentrations of active and/or marker compounds and nutritional and toxic elements in samples distributed by NIST. Data are compiled at NIST where they are analyzed for accuracy, precision, and concordance within the community. Reports and certificates of completion are sent to participants, and workshops are held to discuss results as well as methodological advancements in the characterization of dietary supplements.
The NIST Micronutrients Measurement Quality Assurance (QA) Program supports the long-term (months to years) reliability of selected fat- or water-soluble vitamin measurements in human serum and plasma. Results from the comparison studies help participants to make accurate clinical and health-care decisions as well as to maintain and improve their measurement comparability. Laboratories use the program to demonstrate their compliance with federally regulated requirements [Clinical Laboratory Improvement Act (CLIA)], which extend to all laboratories performing diagnostic testing.
The National Institute of Standards and Technology (NIST) and the National Institutes of Health (NIH) Office of Dietary Supplements (ODS) have established a Vitamin D Metabolites Quality Assurance Program (VitDQAP). Interlaboratory comparison studies are currently directed toward the measurement of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 in selected serum and plasma matrices as well as method-appropriate control materials. Value-assignment of the samples is based on the median of all the laboratory results, with confirmation based on measurement at NIST using two or more different methods. Consultation and troubleshooting regarding methods of analysis are also provided.
The marine mammal interlaboratory comparison program was initiated in the early 1990s as informal comparisons among NIST, NOAA, and several other laboratories. By 2000 the measurement of trace elements and organic contaminants in marine mammal tissues was formalized in annual or biennial interlaboratory exercises. Since that time, participation has increased dramatically both domestically and internationally. In addition to providing an assessment of interlaboratory measurement comparability, the organic contaminant exercise has also provided information on new constituents, including fatty acids and brominated flame retardants in SRM 1945 Organics in Whale Blubber, which has been used routinely as a control material for the exercises. The trace element exercise has resulted in the development of three trace element control materials from marine mammal livers, a pilot whale liver homogenate in 1991 and beluga whale and pygmy sperm whale liver homogenates in 1997 and 2003, respectively.
The NIST Intercomparison Program for Organic and Inorganic Contaminants in the Marine Environment was established to provide a tool for assessing the interlaboratory and temporal measurement comparability for polycyclic aromatic hydrocarbons, polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides in bivalve mollusk, sediment, and fish samples. The program includes components for developing improved analytical methods, producing NIST Standard Reference Materials (SRMs) and other control materials, conducting annual interlaboratory comparison exercises, and coordinating workshops to discuss exercise results.
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