Uses (and Abuses) of Reference Materials for Environmental Analyses
Oral Presentation
Prepared by H. McCarty, K. Roberts
CSC Government Solutions - a CSRA company, 6361 Walker Lane, Suite 300, Alexandria, VA, 22310, United States
Contact Information: [email protected]; 703-462-2392
ABSTRACT
Reference materials and reference matrices have a long history as useful and important tools in analytical chemistry and environmental analyses. Various government agencies and commercial entities now provide an impressive array of reference materials that are stable, homogeneous, well-characterized in terms of not only environmental contaminants and other constituents, and have statistically based or consensus values for the analytes of interest. Reference matrices are often used as the basis for common quality control samples such as method blanks and laboratory control samples and are prepared from readily available sources such as reagent-grade water or Ottawa sand. Analytical methods from EPA, other government sources, and voluntary consensus standards bodies rely on reference materials and reference matrices as means by which environmental laboratories can and must demonstrate initial and day-to-day competency.
Reference materials and matrices also are critical to evaluating the effects of changes to laboratory procedures and equipment by providing something with known values or expected ranges of values. The role of these materials can be critical to EPA and to data users attempting to evaluate alternate test procedures and/or laboratory efforts to invoke the allowances for flexibility in “performance-based methods” such as those approved for compliance monitoring. Unfortunately, the relevance of the reference material or matrix to the actual samples of interest is often overlooked in a rush to “prove” that a cost- or time-saving method modification generates “equivalent” results. Astounding, and occasionally amusing, examples of the use and abuse abound. After an overview of appropriate uses, we present a few of our favorite abuses.
Oral Presentation
Prepared by H. McCarty, K. Roberts
CSC Government Solutions - a CSRA company, 6361 Walker Lane, Suite 300, Alexandria, VA, 22310, United States
Contact Information: [email protected]; 703-462-2392
ABSTRACT
Reference materials and reference matrices have a long history as useful and important tools in analytical chemistry and environmental analyses. Various government agencies and commercial entities now provide an impressive array of reference materials that are stable, homogeneous, well-characterized in terms of not only environmental contaminants and other constituents, and have statistically based or consensus values for the analytes of interest. Reference matrices are often used as the basis for common quality control samples such as method blanks and laboratory control samples and are prepared from readily available sources such as reagent-grade water or Ottawa sand. Analytical methods from EPA, other government sources, and voluntary consensus standards bodies rely on reference materials and reference matrices as means by which environmental laboratories can and must demonstrate initial and day-to-day competency.
Reference materials and matrices also are critical to evaluating the effects of changes to laboratory procedures and equipment by providing something with known values or expected ranges of values. The role of these materials can be critical to EPA and to data users attempting to evaluate alternate test procedures and/or laboratory efforts to invoke the allowances for flexibility in “performance-based methods” such as those approved for compliance monitoring. Unfortunately, the relevance of the reference material or matrix to the actual samples of interest is often overlooked in a rush to “prove” that a cost- or time-saving method modification generates “equivalent” results. Astounding, and occasionally amusing, examples of the use and abuse abound. After an overview of appropriate uses, we present a few of our favorite abuses.
