Measurement services support the NIST Standard Reference Materials Program (SRMs), NIST calibration services, and NIST Standard Reference Datasets. This project represents a responsibility of the Statistical Engineering Division that has been ongoing almost since the division was formed in 1947.
Over the years, the SRM activity has grown from dealing with only a few selected (SRMs) to the current situation in which essentially all NIST SRMs receive some amount of statistical attention.
The customers for these services are industry and scientists/researchers who need NIST-traceable standards.
The objective of this project is assure that certifications and uncertainty statements associated with NIST Standard Reference Materials are on a solid scientific foundation. SRMs are artifacts or chemical mixtures that are manufactured according to strict specifications, and are then certified by NIST for one or more physical or chemical properties of interest. SRMs are a primary vehicle used by NIST for disseminating measurement technology to industry. Staff of the Statistical Engineering Division (SED) collaborate with NIST scientists on:
Because of the large numbers of SRMs in production at NIST, the SED has searched for ways to routinize certifications and uncertainty assessments for SRMs that are restocked on a regular schedule. A process has been put in place for assessing homogeneity and computing certified values and associated uncertainties for' gas cylinder SRMs where data are taken according to a standardized design and then can be analyzed using SED-designed spreadsheet templates. This program has proven successful so that these chemists now look to SED for specialized guidance only where data exhibit anomalous behavior.
The following are SRM related publications.
G. A. Candela, D. Chandler-Horowitz, J. F. Marchiando, D. B. Novotny, B. J. Belzer, M. C. Croarkin. "Standard Reference Materials: Preparation and Certification of SRM-2530, Ellipsometric Parameters and Psi and Derived Thickness and Refractive Index of a Silicon Dioxide Layer on Silicon," NIST Special Publication 260-109, 1988.
S. Schiller, S. and Keith R. Eberhardt. "Combining Data from Independent Chemical Analysis Methods," Spectrochimica Acta, December, 1991.
D. Becker, R. Christensen,L. Currie, B. Diamondstone, K. Eberhardt, T. Gills, H. Hertz, G. Klouda, J. Moody, R. Parris, R. Schaffer, E. Steel, J. Taylor, R. Watters and R. Zeisler. "Use of NIST Standard Reference Materials for Decisions on Performance of Analytical Chemical Methods and Laboratories," NIST Special Publication 829, 1992, 30 pp.
J. Fu, M. C. Croarkin and T. V. Vorburger. "The Measurement and Uncertainty of a Calibration Standard for the Scanning Electron Microscope." NIST Journal of Research., Vol. 99(2), 1994, p.191-200.
Schantz, M. M., Loster, B. J., Oakley, L. M., Schiller, S. B., and Wise, S.A. "Certification of SRM 1945, Organics in Whale Blubber," Proceeding of the Sixth International Symposium on Biological and Environmental Reference Materials, 1994.
Schantz, M. M., Loster, B. J., Oakley, L. M., Schiller, S. B, and Wise, S.A. "Certification of Polychlorinated Biphenyl Congeners in a Whale Blubber Standard Reference Material," Journal of Analytical Chemistry, Vol 67, No 5, March 1, 1995.
K.J. Coakley, S.S.-C. Tai, R.G. Christensen, P. Ellerbe, T. Long, M. Welch. "The Certification of Phencyclidine in Lyophilized Human Urine Reference Materials," Journal of Analytical Chemistry, 20, 1996, pp. 43-49.
T.V. Vorburger, J. F. Song, C.H.W. Giauque, T.B. Renegar, E.P. Whitenton, C. Croarkin. "Stylus-laser Surface Calibration System," Precision Engineering, 1996, p. 157-163.
M.G. Vangel, M.S. Levenson, M. Behlke, R. Saraswati, E. Mackey, R. Demiralp, B. Porter, V. Mandic, S. Azemard, M. Horvat, K. May, H. Emons, S. Wise. "Certification of Three Mussel Tissue Standard Reference Materials (SRMs) for Methylmercury and Total Mercury Content," Freenius', Journal of Analytic Chemistry, Vol 358, No 3, 1997, pp. 431-440.
C.M. Wang and J.D. Splett, "Consensus values and reference values illustrated by the Charpy machine certification program," Journal of Testing Evaluation, 25 (3), 1997, pp. 308-314.
J. R. Ehrstein and C. Croarkin. "Standard Reference Materials: The Certification of 100 mm Diameter Silicon Resistivity SRMs 2541 through 2547 using Dual-Configuration Four-Point Probe Measurements," NIST Special Publication 260-131, August 1997, 84p.
A.L. Rukhin and M.G. Vangel, "Estimation of a Common Mean and Weighted Means Statistics," Journal of the American Statistical Association, 93, pp. 303-309, 1998.
S.L. Gilbert, W.C. Swann and C. M. Wang. "Standard Reference Materials: Hydrogen Cyanide H(13)(14)N Absorption Reference for 1530-1560 nm Wavelength Calibration - SRM 2519," NIST Special Publication 260-137, 1998.
C.M. Wang, C.N. McCowan, D.P. Vigliotti. "Charpy Impact Verification Data (1994-1996): A Summary," Journal of Testing and Evaluation, 27, (2), 1999, pp. 89-99.
G. W. Mulholland, N. P. Bryner, C. Croarkin. "Measurement of the 100 nm NIST SRM 1963 by Differential Mobility Analysis," submitted.
L.M. Gill, V. Iyengar, R. Greenberg, J. Colbert, W. Wolf. "Certification of Proximate Constituents, Minor, and Trace Elements in Standard Reference Material, SRM 1548a: Typical Diet," Journal of the Association of Official Analytical Chemists (AOAC) International, submitted.
L.M. Gill, K.E. Sharpless, M. Arce-Osuna, J. Brown Thomas. "Value Assignment of Retinol, Retinyl Palmitate,Tocopherol, and Carotenoid Concentrations in Standard Reference Material 2383: Baby Food Composite," Journal of the Association of Official Analytical Chemists (AOAC) International, to appear.
L.M. Gill, K.E. Sharpless, S.A. Margolis, S.A. Wise. "Certification of Nutrient Concentration in Standard Reference Material 2383: Baby Food Composite," Journal of the Association of Official Analytical Chemists (AOAC) International, to appear.
M.S. Levenson (with S.A. Margolis). "Water Saturated 1-Octanol, a Calibrant at Microgram Water Levels for Karl Fischer Reagents and Instruments," submitted.
M.G. Vangel (with D.L. Poster, M.M. Schantz, and S.A. Wise). "Analysis of Standard Reference Material 1649A, Organics in Urban Dust, for the Determination of Chlorinated Organic Contaminants Associated With Atmospheric Particulate Matter," Environmental Science and Technology, submitted.
R.R. Zarr and E. S. Lagergren. "Development of Thermal Insulation Standard Reference Materials Using 'Good' Experiment Design," Proc. of 24th International Thermal Conductivity Conference and 12th International Thermal Expansion Symposium, 1998.
SRMs are sold to industry for calibrating scientific instruments over an incredibly large variety of chemical, material, dimensional, and optical applications. NIST SRMs offer the highest level of accuracy for this technology transfer, and the success of the program depends entirely on the quality of the SRM certifications and their uncertainties.
The Certificate issued with each SRM carries an acknowledgement of the statistician(s) who collaborated on the certification project. In addition, the Standard Reference Materials Program issues a memorandum of appreciation to the statistician who collaborated on each project.
Techniques for routinizing other SRMs, such as those measured entirely by outside laboratories and issued as NIST traceable materials, will be developed and adopted in the future. Over the years, statements of uncertainty, as they appear on SRM certificates, have been more diverse than uniform, and this creates a problem both for the user community and the Standard Reference Materials Program. SED has been working toward the development and adoption of coherent, uniform methods for reporting uncertainties.