1、Designation: E2857 11 (Reapproved 2016)Standard Guide forValidating Analytical Methods1This standard is issued under the fixed designation E2857; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide describes procedures for the validation ofchemical and spectrochemical analytical methods of analysisthat are used by a metals, ores
3、, and related materials analysislaboratory.1.2 This guide may be applied to the validation of labora-tory developed (in-house) methods, addition of analytes to anexisting standard test method, variation or scope expansion ofan existing standard method, or the use of new or differentlaboratory equipm
4、ent.1.3 This guide may also be used to validate the implemen-tation of standard test methods used routinely by laboratoriesof the mining, ore processing, and metals industry.2. Referenced Documents2.1 ASTM Standards:2E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related Mate
5、rialsE1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical MethodE1763 Guide for Interpretation and Use of Results fromInterlaboratory Testing of Chemical Analysis Methods(Withdrawn 2015)32.2 ISO Standard:4ISO/IEC 17025 General requirements for the compet
6、ence oftesting and calibration laboratories3. Terminology3.1 DefinitionsFor definitions of terms used in this guide,refer to Terminology E135.3.2 Definitions of Terms Specific to This Standard:3.2.1 validation (of an analytical method), nconfirmation,by the provision of objective evidence and examin
7、ation, that amethod meets performance requirements and is suitable for itsintended use.4. Significance and Use4.1 Method validation is a process of demonstrating that themethod meets the required performance capabilities. Interna-tional standards such as ISO/IEC 17025, certifying bodies, andregulato
8、ry agencies require evidence that analytical methodsare capable of producing valid results. This applies to labora-tories using published standard test methods, modified standardtest methods, and in-house test methods.4.2 Although a collaborative study is part of this guide, thisguide may be used by
9、 a single laboratory for method validationwhen a formal collaboration study is not practical. This guidemay also be applied before a full collaboration study to predictthe reliability of the method.4.3 The use of multiple validation techniques described inthis guide increases confidence in the valid
10、ity or application ofthe method.4.4 It is beyond the scope of this guide to describe fully thefundamental considerations in Section 5. For a more descrip-tive definition of these concepts, refer to the InternationalUnion of Pure and Applied Chemistry (IUPAC) technicalreport, “Harmonized Guidelines f
11、or Single Laboratory Valida-tion of Methods of Analysis,”5the IUPAC Compendium ofAnalytical Nomenclature (Orange Book),6and the Eurachempublication, The Fitness for Purpose of Analytical Methods, ALaboratory Guide to Method Validation and Related Topics.75. Fundamental Considerations5.1 During the p
12、rocess of method validation, the user of ananalytical method should apply a number of fundamental tenets1This guide is under the jurisdiction of ASTM Committee E01 on AnalyticalChemistry for Metals, Ores, and Related Materials and is the direct responsibility ofSubcommittee E01.22 on Laboratory Qual
13、ity.Current edition approved Oct. 1, 2016. Published October 2016. Originallyapproved in 2011. Last previous edition approved in 2011 as E285711. DOI:10.1520/E285711R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annua
14、l Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036,
15、http:/www.ansi.org.5M. Thompson, S. Ellison, and R. Wood, “Harmonized Guidelines for Single-Laboratory Validation of Methods of Analysis,” Pure Appl. Chem., Vol 71, No. 2,2002, pp. 835-855. http:/iupac.org/publications/pac6International Union of Pure and Applied Chemistry Compendium of AnalyticalNom
16、enclature: Definitive Rules 1997, http:/old.iupac.org/publications/analytical_compendium/7EURACHEM Guide, The Fitness for Purpose of Analytical Methods, ALaboratory Guide to Method Validation and Related Topics, LGC, Teddington,Middlesex, United Kingdom, 1998. www.eurachem.orgCopyright ASTM Internat
17、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1of analytical chemistry as they relate to the development andimplementation of test methods. It is important to make thedistinction between the validation of a test method by astandards-developing organization
18、 and the implementation ofthat test method by a laboratory. Whether the test method wasdeveloped by a committee of experts or by one chemist in acompany laboratory, the laboratory shall implement themethod in the laboratory and shall demonstrate that the methodis being performed sufficiently well an
19、d that the results meetthe goals for data quality. That is, they should ascertain that themeasurement process provides sufficient levels of performancefit for the purpose of testing the materials at hand. It isadvisable to determine and document performance character-istics of the method including r
20、epeatability precision, limit ofdetection, limit of quantification, and perhaps other parameters.The laboratory is advised to evaluate the method for bias andfor susceptibility to introduction of bias (namely, ruggedness).A number of important considerations are discussed in5.1.1-5.1.7, but specific
21、 procedures for determination andcalculation are beyond the scope of this guide.NOTE 1In the following discussion, the term measurement process istaken to mean the entire process by which a laboratory performs a testincluding sample preparation, measurements, and calculation of results.5.1.1 Precisi
22、onThe first step in development and imple-mentation of an analytical method is demonstration thatmeasurements can be made with sufficient repeatability for thepurpose of quantitative analysis. Precision is defined as thedegree of agreement among a set of values. Precision underrepeatability conditio
23、ns is measured by having a single analystin a single laboratory use a single set of equipment to prepareand analyze portions of a homogeneous material. Precisionunder reproducibility conditions is measured by having anumber of different analysts at different laboratories prepareand analyze portions
24、of a homogeneous material. Any numberof conditions intermediate between repeatability conditionsand reproducibility conditions may be used if the data serves auseful purpose. A good example is having multiple analysts ina single laboratory perform the analyses, perhaps on multipledays. In the termin
25、ology of Committee E01, repeatability issynonymous with within-laboratory standard deviation, Sr,which is defined as the standard deviation of results collectedon the same material in the same laboratory on different days.In contrast, reproducibility is synonymous with between-laboratory standard de
26、viation, SR, which is defined as thestandard deviation of results obtained on the same material indifferent laboratories.5.1.1.1 The most common estimators of precision are stan-dard deviation, relative standard deviation, and variance. Equa-tions and examples are available in many texts on statisti
27、cs.5.1.1.2 The concept of maintenance of the repeatability overa period of time is known as statistical control. The laboratorycan implement tools such as control charts to demonstratestatistical control.5.1.2 Limit of Detection (LD)The detection limit is definedas the lowest amount of analyte that
28、can be distinguished frombackground by an analytical method. It is important to dem-onstrate that the measurement process has the capability todetect a significantly lower amount (concentration or massfraction) of the analyte than the laboratory must quantify. Foradditional information, consult the
29、IUPAC Orange Book andthe Currie paper.85.1.3 Limit of Quantification (LQ)The limit of quantifica-tion is defined as the amount of analyte above which theestimated relative standard deviation (RSD) is 10 %. It isimportant to demonstrate and document that the measurementprocess has the capability to q
30、uantify amounts less than orequal to those found in materials to which the test method isapplied. For additional information, consult the IUPAC OrangeBook and the Currie paper.85.1.4 BiasBias is the difference between the obtainedresult for a measurand and the true value of the measurand. Ananalytic
31、al method may be subject to a known amount of biasthat was estimated when the standard test method was devel-oped and validated by a committee. In an analogous manner, alaboratory developing a new test method or implementing apublished standard test method shall perform tests to estimatebias and dem
32、onstrate the methods resistance to introduction ofadditional bias, that is, ruggedness. Documentation of thisperformance enables the laboratory to elucidate the scope ofthe method and defend the results obtained using the method.NOTE 2Accuracy is a concept related to both bias and precision. It isth
33、e combination of knowledge of both the precision obtainable undervarious conditions and the amount of bias inherent in a given result. Theconcept of accuracy is often used in discussions of the fitness for purposeand the reliability of results from a test method. In a published standardtest method,
34、the statements of precision and bias taken together providethe basis for judgments of the accuracy of the test method.5.1.5 SelectivityThe selectivity of a method is its ability toproduce a result that is not subject to change in the presence ofinterfering constituents. The selectivity of a method c
35、an beinvestigated by introducing or varying amounts of substancesand evaluating the results for changes. By understanding theprincipal of measurement, the analyst may be able to define ashort list of suspected interferences and, thereby, limit theamount of effort needed to establish the significant
36、interferenceeffects.5.1.6 Calibration ModelRelative methods require calibra-tion using measurements of suitable reference materials andmathematical fitting of the measured responses to an algorithm,that is, an equation thought to describe adequately the relation-ship between the amount of analyte an
37、d the measured response.Algorithms are almost always an approximation of the realworld, and as such, their ability to fit the data has limits that canbe tested by a variety of means including, but not limited to,analyses of certified or other reference materials and statisticalevaluation of confiden
38、ce intervals bracketing the calibrationcurve and extrapolating performance predictions beyond therange of the calibrants.5.1.6.1 Working RangeThe term working range is a namegiven to the concept of a portion of a calibration curve thatprovides valid results as opposed to portions that are not fit fo
39、rpurpose. The range in which the method is considered to bevalid can be characterized using a number of approaches. The8L. A. Currie, “Nomenclature in Evaluation of Analytical Methods IncludingDetection and Quantification Capabilities,” Pure Appl. Chem., Vol 67, No. 10, 1995,pp. 1699-1723. http:/iup
40、ac.org/publications/pacE2857 11 (2016)2preferred methods are those that use objective data for thepurpose of illustrating under which circumstances a calibrationmodel is fit for purpose.5.1.6.2 Calibration PerformanceThere are statisticalmethods for measuring how well the chosen calibrationalgorithm
41、, often a line, fits the data consisting of knownamounts of analyte and measured responses from the analyticalinstrument for the calibrants. For every calibrant, one maycalculate the difference between known and calculatedamounts. This information can be used to describe the perfor-mance of all or p
42、art of the calibration. One can do any of anumber of things with the information, including calculatingthe standard deviation of the differences described above,constructing confidence intervals around all of part of the rangeof amounts, plotting the difference as a function of the amountto look for
43、 trends, and spotting any individual calibrant thatclearly performs more poorly than the rest. Documentingbehaviors like these, seeking the causes, and taking correctiveactions are suggested means to validate a test method.NOTE 3The applications of statistical tools, for example, confidenceintervals
44、 around a calibration, need not be restricted to the region boundedby the lowest and highest calibrants or the lowest and highest validationreference materials measured using the method and a particular calibra-tion. These tools can be extrapolated and still provide valid estimates ofmethod performa
45、nce.5.1.7 RuggednessConsidered in its classical sense, rug-gedness of an analytical method is the resistance of the resultsto change caused by variations in the operational aspects of atest method. Operations characteristics may include substitu-tion of machines used to prepare a specimen, substitut
46、ion ofsources of reagents and ingredients, changes to environmentalconditions, and even changes of personnel. A task group of astandard development committee will perform ruggednesstesting at an early stage in the validation process and at a smallnumber of laboratories before a larger set of laborat
47、ories areasked to invest in an interlaboratory study. The laboratoryimplementing a test method is advised to perform their ownruggedness tests at any time during implementation and regularuse of the method to identify and document effects of changesof these types.6. Means of Method Validation6.1 Onc
48、e method development following the considerationsof Section 5 has been completed, evidence validating methodincrease the confidence that the method performance is accept-able for meeting measurement quality objectives. The valida-tion methods are described in the following sections.6.2 Analysis of R
49、eference Materials:6.2.1 Select a number of reference materials such that theanalyte amount encompasses the intended scope of the analyti-cal method.6.2.2 Analyze each reference material to determine theanalyte amount present. Replicate determinations may be madeif these data are to be used to estimate typical methodprecision. If possible, analyze reference materials that areindependent from the calibration. Record all results.6.2.3 Compare the reference material results to the valuesassigned for the material by the developing organization.Assess the acceptabilit
