NIST and the Centers for Disease Control and Prevention (CDC) have collaborated to develop SRMs to meet the expanding needs for exposure science measurements of organic contaminants 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.
SRMs have been developed to support quality assurance measurements for contaminants in human fluids. Biomonitoring laboratories will use these SRMs to validate methods and as control materials for specific analyses. We have developed and characterized several human-matrix SRMs for organic contaminants: human serum, human milk, and human urine reference materials. We employed results from multiple analytical methods at NIST and data from collaborating laboratories to assign values to chemical composition. We are also developing robust analytical methods for use by the biomonitoring community.
Two human serum SRMs, two human milk SRMs, and two human urine SRMs have been value assigned for a wide range of organic contaminants based on methods performed at NIST, CDC, and four additional collaborating laboratories.
NIST and CDC are collaborating on the development of seven SRMs that will be useful to the biomonitoring community. These include SRM 1953 Organic Contaminants in Non-Fortified Human Milk, SRM 1954 Organic Contaminants in Fortified Human Milk, SRM 1957 Organic Contaminants in Non-Fortified Human Serum, SRM 1958 Organic Contaminants in Fortified Human Serum, SRM 3672 Organic Contaminants in Smokers' Urine and SRM 3673 Organic Contaminants in Non-fortified Non-smokers' Urine. The fortified serum and milk samples were spiked with a solution containing 172 selected contaminants. The fortified samples contain a concentration of those contaminants at levels five to ten times higher than the median concentrations in the U.S. population. Methods have been developed at NIST and CDC for these measurements in the human serum and human milk materials, and the results from the independent methods were combined to provide certified concentration values for contaminants in those materials. NIST and CDC are characterizing replacement materials for the urine SRMs 3672 and 3673.
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