ASTM D2777-21 PDF

SIGNIFICANCE AND USE 5.1 Following this practice should result in precision-and-bias statements that can be achieved by any laboratory properly using the test method studied. These precision-and-bias statements provide the basis for generic limits for use in the Quality Control section of the test method. Optionally, the detection and quantitation values provide estimates of the level at which most laboratories should be able to achieve confident detection and meet the minimum precision (expressed as relative standard deviation) expected. 5.2 The method specifies the matrices for which the test method is appropriate. The collaborative test corroborates the write-up within the limitations of the test design. An extensive test can only use representative matrices so that universal applicability cannot be implied from the results. 5.3 The fundamental assumption of the collaborative study is that the matrices tested, the concentrations tested, and the participating laboratories are a representative and fair evaluation of the scope and applicability of the test method as written. SCOPE 1.1 This practice establishes uniform standards for estimating and expressing the precision and bias of applicable test methods for Committee D19 on Water. Statements of precision and bias in test methods are required by the Form and Style for ASTM Standards, “Section A21. Precision and Bias (Mandatory).” In principle, all test methods are covered by this practice. However, the variability equations provided in this standard are applicable only to test methods that yield continuous function values. 1.2 Except as specified in 1.4, 1.5, and 1.6, this practice requires the task group proposing a new test method to carry out a collaborative study from which statements for precision (overall and single-operator standard-deviation estimates) and bias can be developed. This practice provides general guidance to task groups in planning and conducting such determinations of precision and bias. 1.3 This practice requires that a task group making a substantive revision to a test method also perform a limited-scale collaborative study (known as a ― comparability study) to evaluate the effect of the revision on the precision and bias statement. This practice provides guidance to task groups for conducting such limited-scale collaborative studies. Examples of substantive modifications may include, but are not limited to, changes in mandatory or allowable instrumentation, reagents, reaction times, etc. 1.3.1 Changes to applicable water matrices in the Scope of a method may constitute a substantive modification under this provision. Only matrices that have been evaluated in an approved collaborative study may be listed in the Scope of a method. It is recognized that the term “matrix” is generally vague. Terms specifying matrix types can cover significantly different chemical constituents, unless the matrix is synthesized to be of a standardized makeup. Substitute Wastewater (Practice D5905) is one such defined matrix. For purposes of this practice, the importance of this requirement is to assist the user of a D19 standard in determining the applicability of the method to their samples. Evaluated matrices should be described with as much detail as possible to minimize misapplication. 1.3.2 A method's concentration-range extension that is deemed to merit additional collaborative testing (even without a method modification that would otherwise be considered substantive) shall require a full collaborative study, as described in 7.1 through 7.5, but only at concentrations representative of the extended range. Note that such a collaborative study could involve as little as a single concentration study in a single reproducible matrix. 1.3.3 Whether a revision to a test method includes substantive modification shall be determined by consensus of the Committee. 1.4 If a full-scale collaborative study is not technically feasible, because...