Dietary Supplement Analytical Methods and Reference Materials Program (AMRM)

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AMRM Glossary of Terms

The measure of exactness of an analytical method, or a measure of how close the "measured" value is to the "true" value or an accepted reference value.
An operation that, under specified conditions, in a first step establishes a relation between the quantity values with "measurement uncertainties" provided by measurement standards and corresponding indications with associated "measurement uncertainties" and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication.
Calibration standard
A measurement standard with a known absolute value. It is a single chemical entity developed to ensure high purity and uniformity for specific analyte.
Certified reference material (CRM)
A reference material characterized by a metrologically valid procedure for one or more specified properties, accompanied by a certificate that provides the value of the specified property, its associated uncertainty, and a statement of metrological traceability. Certified reference materials are traceable to international standards with a known uncertainty and therefore can be used to address all aspects of bias (method, laboratory, and within-laboratory) simultaneously, assuming that there is no matrix mismatch.
Collaborative study validation
The interlaboratory collaborative study is a widely accepted procedure to validate any new analytical method. Methods are validated through independent testing in separate laboratories following the same protocol and analyzing the same samples. The purpose of the study is to establish the characteristics of the methods with respect to accuracy, precision (repeatability and reproducibility), sensitivity, range, and specificity.
The initial sets of experiments that that create optimal method performance in terms of predefined criteria, such as detection limits, limits of quantitation, accuracy, and precision. A method that provides all or most of the original method requirements is deemed optimized and becomes ready for validation. It requires an iterative procedure, constant replication, and the acquisition of a large amount of quantitative statistical data.
The measure of degree of repeatability of an analytical method under normal operation. The closeness of agreement between independent test results obtained under stipulated conditions. A measure of how close discrete measurements are to each other.
Reference material
A generic term that refers to a material or substance whose property values are sufficiently homogeneous and stable with respect to one or more specified properties, and whose fitness is well established for its intended use in a measurement process (e.g., calibration of an apparatus, the assessment of a measurement method, or for assigning values to materials). Reference materials may be materials characterized by a reference material producer, but whose values are not accompanied by an uncertainty statement or are otherwise qualified. Traceability of these materials may be questionable.
The degree of reproducibility of the results obtained under a variety of conditions. The resistance to change in the results produced by an analytical method when minor deviations are made from the experimental conditions described in the procedure. Ruggedness of a method is tested by deliberately introducing small changes to the procedure and examining the effect on the results.
Single-laboratory validation (SLV)
A method validation performed within only one laboratory. The results of this validation cannot necessarily be compared with results obtained using a different method or the same method in a different laboratory. SLV debugs the method before it is subjected to a collaborative study and can be considered the first step toward a full AOAC Official Methods of AnalysisSM validation. SLV can provide information about repeatability, but not reproducibility.
Standard reference material (SRM®)
An authenticated material, created in accordance with Standard National Institute for Standards and Technology (NIST) metrological approaches.
A process of distinct steps providing documented evidence that an analytic method does what it is intended to do. Validation applies to a defined protocol, for the determination of a specified analyte (the substance being analyzed) and range of concentrations in a specified type of test material (matrix) with a high degree of accuracy and precision, used for a specified purpose.
Voluntary consensus standards body
The Office of Management and Budget within the US Executive Office of the President defines voluntary consensus standards bodies as domestic or international organizations that plan, develop, establish, or coordinate voluntary standards using agreed-upon procedures. These bodies may include nonprofit organizations, industry associations, accredited standards developers, professional and technical societies, institutes, committees, task forces, or working groups. Participation of government representatives in these bodies is encouraged to increase the likelihood that the standards they develop will meet both public and private sector needs. A voluntary consensus standards body observes principles such as openness, balance of interest, and due process. Voluntary consensus standards bodies operate by consensus (general agreement), but not necessarily unanimity, characterized by the absence of sustained opposition to substantial issues by any important part of the concerned interests. Consensus requires that all views and objections be considered and that an effort be made toward their resolution.