NIST and the Centers for Disease Control and Prevention (CDC) collaborate to develop SRMs to meet the expanding needs for exposure science measurements of organic compounds in human fluids: two serum SRMs -- one natural level (non-fortified) and one fortified; two milk SRMs -- one natural level (non-fortified) and one fortified; and two urine SRMs -- one natural level collected from non-smokers one natural level collected from smokers. Results from measurements made at NIST and CDC and data from interlaboratory studies were used for value assignment of these SRMs.
SRM 1953 Contaminants in Human Milk (non-fortified) and SRM 1954 Contaminants in Human Milk (fortified).
Standard Reference Materials (SRMs) have been specifically designed to assist in the quality assurance measurements for compounds found in human fluids. Clinical and biomonitoring laboratories rely on these SRMs for method validation and as control materials during specific analyses. Various human-matrix reference materials, such as human serum, human milk, and human urine, have been meticulously developed and characterized. The chemical composition values are determined through multiple analytical methods at the National Institute of Standards and Technology (NIST) and collaborating laboratories.
Moreover, efforts are underway to establish robust analytical methods for use by the biomonitoring community. NIST and the Centers for Disease Control and Prevention (CDC) are actively engaged in a collaborative effort to create SRMs that will significantly benefit the biomonitoring field. Samples of fortified serum and milk have been intentionally spiked with a solution containing 172 selected contaminants. These fortified samples are at levels five to ten times higher than the typical concentrations found in the U.S. population. Currently, NIST and CDC are characterizing replacement materials for the urine SRMs 3672 and 3673 to standardize the measurement of smoking metabolites used to assess nicotine and secondhand smoke exposures.
These human matrix reference materials help the clinical and research community ensure cross-laboratory and multi-year comparability in long term studies of human health.