1、Designation: E2093 12 (Reapproved 2016)Standard Guide forOptimizing, Controlling and Assessing Test MethodUncertainties from Multiple Workstations in the SameLaboratory Organization1This standard is issued under the fixed designation E2093; the number immediately following the designation indicates
2、the year oforiginal adoption or, in the case of revision, the year of last revision. A number in 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 a protocol for optimizing,c
3、ontrolling, and reporting test method uncertainties from mul-tiple workstations in the same laboratory organization. It doesnot apply when different test methods, dissimilar instruments,or different parts of the same laboratory organization functionindependently to validate or verify the accuracy of
4、 a specificanalytical measurement.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limita
5、tions prior to use.2. Referenced Documents2.1 ASTM Standards:2E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE350 Test Methods for Chemical Analysis of Carbon Steel,Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, andWrought IronE415 Test Method for Ana
6、lysis of Carbon and Low-AlloySteel by Spark Atomic Emission SpectrometryE1329 Practice for Verification and Use of Control Charts inSpectrochemical AnalysisE1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical MethodE2027 Practice for Conducting Proficien
7、cy Tests in theChemicalAnalysis of Metals, Ores, and Related Materials2.2 ISO Standards:3ISO/IEC 17025 General Requirements for the Competenceof Calibration and Testing LaboratoriesISO 9000 Quality Management and Quality System Ele-ments2.3 Other Standards:Measurement Systems Analysis Reference Manu
8、al43. 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 workstation, na combination of people and equip-ment that executes a specific test method using a singlespecified measuring device to quantif
9、y one or more parameters,with each report value having an established estimated uncer-tainty that complies with the data quality objectives of thelaboratory organization.4. Significance and Use4.1 Many competent analytical laboratories comply withaccepted quality system requirements. When using stan
10、dardtest methods, their test results on the same sample should agreewith those from other similar laboratories within the reproduc-ibility estimates index (R) published in the standard. Repro-ducibility estimates are generated as part of the interlaboratorystudies (ILS), of the type described in Pra
11、ctice E1601. Com-petent laboratories participate in proficiency tests, such asthose conducted in accordance with Practice E2027, to confirmthat they perform consistently over time. In both ILS andproficiency testing protocols, it is generally assumed that onlyone work station is used to generate the
12、 data.1This 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 Quality.Current edition approved Dec. 1, 2016. Published December 2016. Originallyapproved in 2000. La
13、st previous edition approved in 2012 as E2093 12. DOI:10.1520/E2093-12R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe
14、ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, www.ansi.org or from International Organizationfor Standardization (ISO) at www.iso.ch.4Measurement Systems Analysis Reference Manual, Copyright 1990, 1995,Chrysler Corporation, F
15、ord Motor Company, and General Motors Corporation,available from AIAG, 26200 Lahser Rd., Suite 200, Southfield, MI 480347100,www.aiag.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in acco
16、rdance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14.2 Many laboratories have work
17、loads, or logisticalrequirements, or both, that dictate the use of multiple workstations. Some have multiple stations in the same area (centrallaboratory format). Other stations are scattered throughout afacility (at-line laboratory format) and in some cases may evenreside at different facilities. O
18、ften, analysis reports do notidentify the workstation used for the testing, even if worksta-tions differ in their testing uncertainties. Problems can arise ifclients mistakenly attribute variation in report values to processrather than workstation variability. These problems can beminimized if the l
19、aboratory organization determines the overalluncertainty associated with results reported from multipleworkstations and assesses the significance of the analyticaluncertainty to the production process.4.3 This guide describes a protocol for efficiently optimiz-ing and controlling variability in test
20、 results from differentworkstations used to perform the same test. It harmonizescalibration and control protocols, thereby providing the samelevel of measurement traceability and control to all worksta-tions. It streamlines documentation and training requirements,thereby facilitating flexibility in
21、personnel assignments.Finally, it offers an opportunity to claim traceability of profi-ciency test measurements to all included workstations, regard-less on which workstation the proficiency test sample wastested. The potential benefits of utilizing this protocol increasewith the number of workstati
22、ons included in the laboratoryorganization.4.4 This guide can be used to identify and quantify benefitsderived from corrective actions relating to under-performingworkstations. It also provides means to track improved perfor-mance after improvements have been made.4.5 It is assumed that all who use
23、this guide will have anestablished laboratory quality system. This system shall in-clude the use of documented procedures, the application ofstatistical control of measurement processes, and participationin proficiency testing. ISO/IEC 17025 describes an excellentmodel for establishing this type of
24、laboratory quality system.4.6 The general principles of this protocol can be adapted toother types of measurements, such as mechanical testing andon-line process control measurements, such as temperature andthickness gauging. In these areas, users may need to establishtheir own models for defining d
25、ata quality objectives andproficiency testing may not be available or applicable.4.7 It is especially important that users of this guide takeresponsibility for ensuring the accuracy of the measurementsmade by the workstations to be operated under this protocol. Inaddition to the checks mentioned in
26、6.2.3, laboratories areencouraged to use other techniques, including, but not limitedto, analyzing some materials by independent methods, eitherwithin the same laboratory or in collaboration with otherequally competent laboratories. The risks associated withgenerating large volumes of data from care
27、fully synchronized,but incorrectly calibrated multiple workstations are obviousand must be avoided.4.8 This guide is not intended to provide specific guidanceon development of statements of measurement uncertaintysuch as those required by ISO/IEC 17025. However, thestatistical calculations generated
28、 using this guide may providea useful estimate of one TypeAuncertainty component used inthe calculation of an expanded uncertainty.4.9 This guide does not provide any guidance for determin-ing the bias related to the use of multiple workstations in alaboratory organization.5. Summary5.1 Identify the
29、 test method and establish the data qualityobjectives to be met throughout the laboratory organization.5.2 Identify the workstations to be included in the protocoland harmonize their experimental procedures, calibrations, andcontrol strategies so that all performance data from all work-stations are
30、directly statistically comparable.5.3 Tabulate performance data for each workstation andensure that each workstation complies with the laboratoryorganizations data quality objectives.5.4 Perform statistical analysis of the data from the work-stations to quantify variation within each workstation and
31、assess acceptability of the variation of the pooled workstationdata.5.5 Document items covered in 5.1 5.4.5.6 Establish and document a laboratory organization-wideproficiency test policy that provides traceability to all work-stations.5.7 Operate each workstation independently as described inits ass
32、ociated documentation. If any changes are made to anyworkstation or its performance levels, document the changesand ensure compliance with the laboratory organizations dataquality objectives.6. Procedure6.1 Test Method Identification and Establishment of theData Quality Objectives:6.1.1 Multi-elemen
33、t test methods can be handledconcurrently, provided that all elements are measured usingcommon technology, and that the parameters that influencedata quality are tabulated and evaluated for each elementindividually. An example is Test Method E415 that covers theanalysis of plain carbon and low alloy
34、 steel by atomic emissionvacuum spectrometry. Workstations can be under manual orrobotic control, as long as the estimated uncertainties arewithin the specified data quality objectives. Avoid handlingmulti-element test methods concurrently that use differentmeasurement technologies. Their procedures
35、 and error evalu-ations are too diverse to be incorporated into one easy-to-manage package. An example of test methods that should notbe combined into one program is Test Methods E350 becausethose methods cover many different measurement technolo-gies.6.1.2 Set the data quality objectives for the ap
36、plication ofthe method throughout the laboratory organization, usingcustomer requirements and other available data. Possiblesources of other data may include production process datademonstrating the need for and values of specific analyticalE2093 12 (2016)2process control limits. At the conclusion o
37、f this effort, thelaboratory organization will know the population standarddeviation at specific concentrations. The laboratory can thenuse these data to draw conclusions about the acceptability ofthe data produced by the population of work stations.6.2 Identify the workstations to be included in th
38、e protocoland harmonize their experimental procedures, calibrations, andcontrol strategies so that all performance data from all work-stations are directly statistically comparable.6.2.1 For each workstation, list the personnel and equipmentthat significantly influence data quality. Each component o
39、feach workstation does not have to be identical, such as fromthe same manufacturer or model number; however, eachworkstation must perform the functions described in the testmethod.6.2.2 Harmonize the experimental procedures associatedwith each workstation to ensure that all stations are capable ofge
40、nerating statistically comparable data that can be expected tofall within the maximum allowable limits for the laboratoryorganization. Ideally, all workstations within the laboratoryorganization will have essentially the same experimental pro-cedures.6.2.3 Harmonize calibration protocols so that the
41、 samecalibrants are used to cover the same calibration ranges for thesame elements on all instruments. Avoid the use of differentcalibrants on different instruments that may lead to calibrationbiases and uncertainties that are larger than necessary. Ensurethat all interferences and matrix effects ar
42、e addressed. It isreasonable to expect that similarly configured instruments willyield similar interference and matrix effect correction factors.Validate the analytical method for each workstation. Recordthe findings for each workstation.6.2.4 Use the same SPC materials and data collectionpractices
43、on all work stations (see Note 1). Carry SPCmaterials through all procedural steps that contribute to themeasurement uncertainty. Develop control charts in accor-dance with Practice E1329, or equivalent practice.NOTE 1Generally, it is recommended that SPC concentrations be setabout13 from the top an
44、d13 from the bottom of each calibration range. Itis also recommended that single point, moving range charts be used so thatcalculated standard deviations reflect the normal variation in report values.6.2.5 Collect at least 20 SPC data points from each workstation to ensure that the workstations are
45、under control andthat the control limits are representative.6.3 Tabulate performance data for each workstation.6.3.1 Tabulate the SPC data by parameter (element), Refer-ence material, assumed true concentration, workstation, meanupper control limit, lower control limit, standard deviation, asillustr
46、ated in Table 1 (see Notes 2 and 3).NOTE 2The data in Table 1 were collected over an extended timeperiod on two reference materials using three atomic emission spectrom-eters in a large, integrated steel mill. The data is typical of that producedin an ISO/IEC 17025 compliant laboratory prior to the
47、availability of thisguide.NOTE 3When all workstations are calibrated in accordance with 6.2.3and all SPC charts are generated in accordance with 6.2.4, the grandmeans for each element/material combination should be sufficientlysimilar so as not to contribute significantly to the overall uncertainty
48、of themethod.6.3.2 Calculate the pooled standard deviation for eachelement/SPC reference material for the data produced by thepopulation of work stations. List the values in a manner similarto that shown in Table 1.6.3.3 Calculate the 6 Pooled SD value for each element/SPC reference material using t
49、he pooled SD calculated as per6.4. List the values in a manner similar to that shown in Table1.6.3.3.1 High standard deviations for any item across allwork stations may indicate a problem with the homogeneity ofthe SPC material (see Note 4).NOTE 4The standard deviations for carbon in RM 648 exceeded theexpected precision on all three workstations by a small amount, suggest-ing a possible material problem.6.3.3.2 High standard deviations for any element on anywork station, especially if it shows on more than one SPCmaterial, may indicate a precision problem with that c
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