1、Designation: E882 10 (Reapproved 2016)Standard Guide forAccountability and Quality Control in the Chemical AnalysisLaboratory1This standard is issued under the fixed designation E882; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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 covers the essential aspects of an account-ability and quality control program for a chemical
3、analysislaboratory. The reasons for establishing and operating such aprogram are discussed.2. Referenced Documents2.1 ASTM Standards:2E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE1329 Practice for Verification and Use of Control Charts inSpectrochemical An
4、alysisMNL 7A Manual on Presentation of Data and Control ChartAnalysis32.2 ASQC Document:4ASQC Standard A1 Definitions, Symbols, Formulas, andTables for Control Charts3. Terminology3.1 DefinitionsFor definitions of terms used in this guide,refer to Terminology E135.4. Significance and Use4.1 An accou
5、ntability and quality control system is estab-lished by laboratory management to improve the quality of itsresults. It provides documented records which serve to assureusers of the laboratorys services that a specified level ofprecision is achieved in the routine performance of its mea-surements and
6、 that the data reported were obtained from thesamples submitted. The system also provides for: early warn-ing to analysts when methods or equipment begin to develop abias or show deterioration of precision; the protection andretrievability of data (results); traceability and control ofsamples as the
7、y are processed through the laboratory; goodcommunication of sample information between submitters,analysts, and supervision; and information on sample process-ing history. This guide describes such a system. Other account-ability and quality control programs can be developed. Suchprograms can be eq
8、uivalent to the program in this guide if theyprovide all of the benefits mentioned above.5. Accountability5.1 Accountability means assurance that the results reportedrefer directly to the samples submitted.5.2 Prior to submitting samples to the laboratory, the pro-spective user should consult with l
9、aboratory personnel con-cerning his needs and the capability of the laboratory to satisfythem. It is the responsibility of the originator of the samples toselect and identify proper samples for submission to thelaboratory, to decide what information is required, and, afterconsulting with laboratory
10、personnel, to submit the samples insuitable containers, properly labeled, and accompanied bywritten instructions identifying the samples, their nature, andthe information sought through chemical analysis. This shouldbe done formally, using a well-defined document for informa-tion transfer to initiat
11、e work in the laboratory.5.3 Laboratory management establishes a written account-ability system to be used throughout the laboratory at all times.This implies traceability and documentation of all reportedresults through the laboratory back to the submitted sample.This system should have the followi
12、ng general characteristics:5.3.1 Each testing request submitted by a user of thelaboratorys services is assigned an internal laboratory identi-fication number (ID), which is used to correlate all samples,work, time, and cost accounting, consultation, and reports andother paperwork associated with th
13、at request. The final reportthat is returned to the originator will always bear the number(ID) for future reference. Moreover, it is convenient forlaboratory data to be filed according to sequential ID numbers.For example, “86/0428” might identify the associated work asthe 428th request submitted in
14、 the year 1986. The Data Recordshould provide all data generated during the analyses, names of1This 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.Curren
15、t edition approved Dec. 1, 2016. Published December 2016. Originallyapproved in 1982. Last previous edition approved in 2010 as E882 10. DOI:10.1520/E0882-10R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o
16、f ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3ASTM Manual Series, ASTM, 7th Edition, 2002.4Available from American Society for Quality (ASQ), 600 N. Plankinton Ave.,Milwaukee, WI 53203, http:/www.asq.org.Copyright ASTM International, 100 Barr Ha
17、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommenda
18、tions issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1persons performing the analyses, dates the analyses wereperformed, and any unusual occurrences that happened duringthe analyses. Accountability for production control samples isnormally maintained separately fr
19、om the other testing recordsbecause results from production control samples are usuallyreported on routine report forms, the samples being identifiedwith the day, shift, run, or lot from which they were taken.5.3.2 Each sample, specimen, sample site, or other uniquepiece of material or container ide
20、ntified as a separate sample bythe originator should be assigned a sequential item number(NN) for internal laboratory use. As soon as the samples areaccepted by the laboratory, laboratory personnel will markeach sample or sample container with its own laboratorysample number (ID-NN) in such manner t
21、hat the label is notlikely to become separated from its sample or renderedunreadable during its residence in the laboratory. For example,the fifth sample on the above-mentioned request might beidentified as “86/0428-05.”5.3.3 All laboratory work records, intermediate samplecontainers, data, and repo
22、rts for a specific sample will beidentified by the same laboratory identification and itemnumber to avoid any opportunity for samples or data to be lostor intermixed within or between requests.5.3.4 The first and last steps in the accountability procedureare functions of technical supervision. Befor
23、e any work isperformed, the compatibility of the work requested with thephysical condition of the samples and the capabilities of thelaboratory must be verified. When the analysts have completedtheir work, the results must be reviewed to be certain that allinformation requested has been determined a
24、nd that the workhas been performed with the required care and precision. Inthis latter regard, quality control procedures prove invaluableboth to the analysts performing the work and the reviewingsupervisor. The supervisor also verifies that the results arecalculated in units that are most meaningfu
25、l to the submitterand that the units and basis on which the results are calculatedare clearly stated.5.3.5 Except for the most routine work, the original ana-lysts data book, a serial listing of laboratory identificationnumbers and descriptions, and a copy of each job report areretained in the labor
26、atorys records for the periods of timeestablished by laboratory policy. Intermediate calculations andsamples are normally discarded after the submitter has had areasonable opportunity to submit questions concerning theresults and request return of his samples. In some cases,customer specifications m
27、ay dictate the records that must beretained and the retention times for both analytical records andlaboratory samples.6. Quality Control6.1 Quality control of analytical methods provides theinformation needed to ensure that procedures, equipment, andpersonnel are performing at the levels of precisio
28、n and accu-racy required by the intended use of the data.6.2 General CharacteristicsThe following factors havebeen found helpful in maximizing the effectiveness and mini-mizing the cost of quality control procedures:6.2.1 Involve the operators or analysts who actually performthe work to the greatest
29、 possible extent.6.2.2 Use the simplest, most direct statistical proceduresthat will provide the necessary degree of control. This meansthat graphical or simplified arithmetic procedures are preferred.6.2.3 Perform the quality control measurements as early inthe measurement process as possible. This
30、 prevents waste ofanalytical effort if the method is not initially in control.However, when a prolonged series of measurements is made, itis also necessary to verify that the method remains in controlthroughout the run.6.2.4 Provide specific action limits and describe exactlywhat must be done when t
31、hese limits are exceeded.6.2.5 For each method (for each sample type), choose acontrol material that is known to be stable, homogeneous andhas measured values within the range of interest. Any inhomo-geneity in the control sample will add to the variance of theresults. Any increase in variability th
32、at is not related to themeasurement process will reduce the sensitivity of the qualitycontrol procedure to detect changes in the measurementprocess. Where possible, the control material should be similarto the samples to be analyzed. Obtain as large an amount ofcontrol material as can be prepared in
33、 a homogeneous statebecause considerable effort is required to prepare a newcontrol.Always prepare a new control material well in advanceof exhausting the old one so that the new supply is ready whenneeded. In situations where satisfactory control material cannotbe obtained, alternative techniques (
34、such as, retest by a senioranalyst) may be substituted for the control material approach.6.2.6 Give analysts specific instructions concerning theirresponse to an out-of-control condition. Supervision maydecide that, if the analyst can correct the problem so that thecontrol sample results are again w
35、ithin limits, the process maycontinue without immediate contact with the supervisor. Inother situations, the supervisor may need to become involvedwith each out-of-control incident. In either case, adjustments tothe process should be recorded to explain each shift in thecontrol measurements.6.2.7 Pr
36、ovide for a periodic in-depth review by supervisionand management of the overall effectiveness of the laboratoryquality control system. Operating experience may indicate thatmethods should be added to, or dropped from the program, thatthe frequency of specific control samples should be increasedor d
37、ecreased, or that a different strategy might be moreappropriate for control of a specific method. The interval forsuch reviews should be determined by the uniformity of theprocesses that generate the samples. Any anticipated or ob-served change in the character of the samples being analyzedshould in
38、itiate at least a cursory review of the control proce-dures for the methods that apply to those samples.6.3 Laboratory Quality Control StrategiesControl chartmethods are suitable for laboratory quality control programs.The choice of which control strategy to use depends oncircumstances: the type of
39、instrument or laboratory procedure,the number of samples and frequency of the analyses, and thecloseness of control required. The following are appropriate:6.3.1 The X- and R-chart method is most frequently used.The control sample is run two or more times during the run,E882 10 (2016)2batch, or shif
40、t. The average is plotted on the X-chart and theabsolute value of the difference between the high and lowvalues, the range, is plotted on the R-chart. If the average fallsbetween the upper and lower control limits and the range fallsbelow the upper control limit, the process is considered to be inco
41、ntrol. Fig. 1 shows the essential features of charts foraverages and ranges.6.3.2 The X-chart method (often called the control chart forindividuals) is useful for measurements that are made on afrequent or continual basis. It is appropriate for methods orinstruments for which the usual mode of failu
42、re producesrelatively large shifts in results and the cost of a determinationprecludes performing replicate analyses of control samples. Itsmain characteristic is that it responds rapidly to suddenrelatively large changes in the analytical process, but it is notas sensitive to small changes as the X
43、- and R-chart method.Each time the control material is analyzed, its value is plottedon the -chart. If the point plots between the upper and lowercontrol limits, the analytical process is considered to be incontrol. Fig. 3 shows the essential features of charts forindividuals.6.3.3 A combination of
44、the above two methods constitutes auseful strategy. A fixed number of control sample runs aremade during a period that samples are being analyzed (suchperiod could, for example, be a shift or a day in a continuousanalysis process). Each individual value is plotted on theX-chart as the measurement is
45、 completed. Their average valueand range are plotted on the X- and R-charts. The additionaleffort to prepare and maintain both types of control charts maybe justified in situations where erroneous assays would causelarge economic losses. Other control chart techniques that maybe appropriate for spec
46、ial circumstances may be found in theASQC Standard A1 document.6.3.4 Comparison with certified reference materials (CRMs)is frequently the only strategy that can be employed forinfrequently used analytical methods or for non-routine sampletypes. If a CRM (from the National Institute of Standards and
47、Technology or other CRM producer) similar to the samples incomposition is tested with the samples, comparison of themeasured value to the assigned value of the CRM provides ameasure of confidence in the sample assays. Lacking a CRM,any previously analyzed material may be used. In all cases, itis imp
48、ortant to retain as large a portion of such a material aspossible and to tabulate the results, the method used, the date,and the analyst. Materials and data thus obtained may haveimportant future statistical or control chart use.6.4 Definitions:6.4.1 mean:XH5 X11X21. Xn!/n (1)where:n = the number of
49、 analytical values.6.4.2 grand mean:X%5 XH11XH21XHk!/k (2)where:k = the number of individual means.6.4.3 range:R 5 Xh2 Xl(3)where:Xh= highest observed value, andXl= lowest observed value in the data.6.4.4 average range:RH5 R11R21 Rk!/k (4)FIG. 1 Control Chart for AveragesE882 10 (2016)36.4.5 estimated standard deviation:s 5(Xi2 XH!2n 2 1(5)where:xi= the individual values of successive observations,X= the mean of the values, andn = the number of values.6.5 Control Chart ConstructionCalculate the centralvalue and control limits. Prepare the control chart with
