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NIST Micronutrients Measurement Quality Assurance Program: Performance History of the Fat-Soluble Vitamin-Related Studies



David L. Duewer, Jeanice "Brown Thomas ", Margaret Kline, Willie May, Katherine E. Sharpless


From 1984 to 2017, the National Institute of Standards and Technology (NIST) Micronutrients Measurement Quality Assurance Program (MMQAP) coordinated 79 "Round Robin" (RR) interlaboratory studies designed to improve measurement comparability among laboratories measuring fat soluble vitamins and carotenoids in human serum and plasma. There were 22 participants in the initial study; participation increased to 58 in 1997 and then declined in stages to 29 by 2017. A total of 138 academic, commercial, governmental, or non-governmental organizations actively participated in at least one RR; two laboratories participated in 77 of the 79 RRs. A total of 350 human serum or plasma samples were distributed in the RRs, typically three to five per RR. One hundred thirty one (131) of these samples were unique materials. While the initial RRs focused on just "retinol" (vitamin A), α tocopherol (vitamin E), and "β carotene" (provitamin A) over the life of the program 57 vitamin related measurands were reported at least once. Fifteen (15) measurands were reported sufficiently often to enable analysis of measurement performance over time: total retinol, retinyl palmitate, α tocopherol, γ plus β tocopherol, total β carotene, trans β carotene, total cis β carotene, total α carotene, total lycopene, trans lycopene, total β cryptoxanthin, total lutein, total zeaxanthin, total lutein plus zeaxanthin, and coenzyme Q10. In addition to documenting the number and nature of the MMQAP's participants, measurands, materials, and reported measurements, this report explores the evolution of among-participant concordance and within-participant apparent precision as functions of calendar date documents and the relationships among results reported for materials delivered to participants both as liquid-frozen and lyophilized samples.
NIST Interagency/Internal Report (NISTIR) - 7880-50
Report Number


Apparent Precision, Carotenoids, Coenzyme Q₁₀, Concordance, Human serum, Interlaboratory Measurement Reproducibility Functions, Liquid-Frozen Samples, Lyophilized Samples, Micronutrients Measurement Quality Assurance Program (MMQAP), SRM 968, Retinol, Robust Scale Estimators, Tocopherols


Duewer, D. , "Brown Thomas ", J. , Kline, M. , May, W. and Sharpless, K. (2022), NIST Micronutrients Measurement Quality Assurance Program: Performance History of the Fat-Soluble Vitamin-Related Studies, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed July 18, 2024)


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Created September 21, 2022, Updated November 29, 2022