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Development of SRMs for Accurate Assessment of Exposure to Toxic Elements and Anions


As part of a multi-year interagency agreement between the National Institute of Standards and Technology (NIST) and Centers for Disease Control and Prevention (CDC), NIST is developing Standard Reference Materials (SRMs) for toxic elements and anions in frozen human urine. To ensure the stability of the analytes, 26 elements and anions were prepared in two SRMs: SRM 2668 Toxic Elements in Frozen Human Urine contains 21 elements and anions (As, Be, Cd, Cs, Cl, Co, Cu, F-, Pb, Mn, Ni, Pt, Sb, Tl, Sn, W, U, and V), and SRM 3668 Mercury, Perchlorate, and Iodide in Frozen Human Urine contains 5 elements and anions (Hg, I-, ClO4-, NO3-, and SCN-). The SRMs are intended for method validation and quality assurance in clinical measurements that assess human exposure to toxic elements and anions. Specifically, the SRMs are designed for use in the National Health and Nutrition Examination Survey (NHANES) that is conducted by CDC. The materials have been prepared and accepted. Value assignment analyses are underway at NIST and the collaborating laboratories.


Toxic elements in the environment are a threat to public health and safety. Federal and state regulations have been issued to limit and abate the presence of toxic elements in the environment. The levels of toxic elements in the U.S. population are carefully monitored. NHANES is one of the federal programs that uses urine as a proxy to assess the exposure of the US population to toxic elements. The SRMs under development are intended for method validation and quality assurance in NHANES and other similar types of measurements. 

Additional Technical Details:

The frozen urine SRMs under development are a new variation of the SRMs NIST has produced over the years in support of assessment measurement of human exposure to toxic elements. The matrices of the new SRMs closely resemble clinical urine samples, which makes the new SRMs better suited for their intended purpose than the freeze-dried urines previously issued. Lessons learned with SRM 2669 Arsenic Species in Frozen Human Urine are being applied to this project. The candidate SRMs were produced at CDC’s facility in Atlanta, GA. In anticipation of future needs in health and exposure assessment, perchlorate was added to the SRMs for value-assignment. The constituents in the SRMs are being determined by multiple independent methods with measurements performed by NIST and collaborating laboratories. Laboratories participating in the value-assignment measurements include NIST; CDC in Atlanta, GA; Mayo Clinic in Rochester, MN; and Wadsworth Center, New York State Department of Public Health in Albany, NY.

Major Accomplishments:

  • Two frozen-urine SRMs, each containing two levels of analytes, have been produced.    
  • Completed the quality and acceptance testing of the candidate SRMs.    
  • Value-assignment measurements are ongoing at NIST and collaborating laboratories.

Start Date:

August 1, 2007

End Date:


Lead Organizational Unit:



W. Clay Davis
John L. Molloy
Savelas A. Rabb
Stephen E. Long
Karen E. Murphy
Laura J. Wood
Lee L. Yu
Rolf L. Zeisler


Lee L. Yu
Phone 301-975-4127

Gregory C. Turk
Phone 301-975-4118

Stephen A. Wise
Phone 301-975-3112