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NIST Micronutrients Measurement Quality Assurance Program Sample Integrity Confirmation



David L. Duewer, Jeanice Brown Thomas, Stephen Young


From 1984 to 2017, the National Institute of Standards and Technology (NIST) Micronutrients Measurement Quality Assurance Program (MMQAP) coordinated a series of "Round Robin" interlaboratory comparability improvement studies for laboratories that measured fat-soluble vitamins and carotenoids in human serum and plasma. The MMQAP distributed 352 human serum or plasma samples over the course of 79 studies, of which 134 were unique materials. Most of the 95 materials produced prior to 2001 were lyophilized serum; most produced thereafter were liquid-frozen serum. During the period 2000 to 2002 six materials were prepared as lyophilized, liquid-frozen} pairs to enable direct comparison of sample integrity and stability. While all samples were nominally continuously stored at 80 °C, most materials were subjected to numerous freeze-thaw cycles during sample selection and labeling as well as episodic relocations. This report details the analysis of a set of 48 unique materials produced from 1987 to 2009 that were evaluated synchronously in 2014 by an experienced participant (1995 to 2017) in the MMQAP studies. These materials include 5 of the 6 lyophilized, liquid-frozen} pairs and the 12 components of the Standard Reference Material® (SRM®) 968 family of certified references materials produced prior to 2014.
NIST Interagency/Internal Report (NISTIR) - 7880-49
Report Number


Carotenoids, Human serum, Lyophilized samples, Liquid-frozen samples, Retinol, Tocopherols


Duewer, D. , Brown Thomas, J. and Young, S. (2022), NIST Micronutrients Measurement Quality Assurance Program Sample Integrity Confirmation, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed June 12, 2024)


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Created June 30, 2022, Updated November 29, 2022