Over the last three decades, NIST, with support from the Centers for Disease Control (CDC), and in conjunction with the New York State Department of Health’s (NYSDOH) Wadsworth Center, has produced a number of frozen whole blood certified reference materials containing endogenous lead (Pb). These are used by clinical laboratories to evaluate the accuracy of blood lead concentration measurements and for use in validating working or secondary reference materials for lead in blood analysis. Starting with the issue of SRM 955c, additional toxic elements and species were spiked into the blood in order to serve both the Pb testing and the toxic metals measurement communities. Mercury toxicity is dependent on chemical form, necessitating measurement of the specific mercury species. Ethyl mercury is a concern, because it is a metabolite of thimersol, which has been used as a preservative in vaccine and is being studied in the proposed link between autism and mercury exposure. Arsenic, Cd, and THg are typically analyzed in concert as a “heavy metal screen” for diagnosis of acute poisoning, utilizing the multi-element analysis method, inductively coupled plasma mass spectrometry (ICP-MS). Half of all blood analyses in the U.S. are performed using ICP-MS. SRM 955c was produced at NYSDOH’s Wadsworth Center from Pb-dosed goats and is comprised of four vials of frozen caprine blood at four concentration levels: a base level and three progressively elevated levels. Each vial contains 2 mL of whole blood. SRM 955c serves multiple measurement communities and is the first available whole blood CRM with ETHg and As values.
To provide a single reference material with expanded analyte coverage that serves the measurement needs of both the childhood/adult Pb testing community and the wider, heavy metal toxicological measurement community.
- Provide a frozen whole blood SRM with certified concentration values for toxic metals and species at multiple levels:
- Baseline level to meet the needs of human exposure assessment studies
- Three elevated levels to meet the needs of child and occupational exposure studies
- Develop new NIST reference methods for the measurement of As and Hg species in whole blood