1、Designation: E882 10 (Reapproved 2016)1Standard 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.1NOTESection 6.5.4 was corrected editorially in October 2017.1. Scope1.1 This guide covers the essential aspects of
3、an account-ability and quality control program for a chemical analysislaboratory. The reasons for establishing and operating such aprogram are discussed.1.2 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Deci
4、sion on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related Ma
5、terialsE1329 Practice for Verification and Use of Control Charts inSpectrochemical Analysis2.2 ASTM Manual:3MNL 7A Manual on Presentation of Data and Control ChartAnalysis2.3 ASQC Document:4ASQC Standard A1 Definitions, Symbols, Formulas, andTables for Control Charts3. Terminology3.1 DefinitionsFor
6、definitions of terms used in this guide,refer to Terminology E135.4. Significance and Use4.1 An accountability 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 servic
7、es that a specified level ofprecision is achieved in the routine performance of its mea-surements and 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 pre
8、cision; the protection andretrievability of data (results); traceability and control ofsamples as they 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
9、a system. Other account-ability and quality control programs can be developed. Suchprograms can be equivalent 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 sub
10、mitted.5.2 Prior to submitting samples to the laboratory, the pro-spective user should consult with laboratory 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 submi
11、ssion to thelaboratory, to decide what information is required, and, afterconsulting with laboratory personnel, to submit the samples insuitable containers, properly labeled, and accompanied bywritten instructions identifying the samples, their nature, andthe information sought through chemical anal
12、ysis. This shouldbe done formally, using a well-defined document for informa-tion transfer to initiate 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 re
13、portedresults through the laboratory back to the submitted sample.This system should have the following general characteristics:1This guide is under the jurisdiction of ASTM Committee E01 on AnalyticalChemistry for Metals, Ores, and Related Materials and is the direct responsibility ofSubcommittee E
14、01.22 on Laboratory Quality.Current edition approved Dec. 1, 2016. Published December 2016. Originallyapproved in 1982. Last previous edition approved in 2016 as E882 10 (2016).DOI: 10.1520/E0882-10R16E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S
15、ervice at serviceastm.org. For Annual Book of 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.o
16、rg.Copyright ASTM International, 100 Barr Harbor 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 In
17、ternational Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15.3.1 Each testing request submitted by a user of thelaboratorys services is assigned an internal laboratory identi-fication number (ID), which is used to correlate a
18、ll samples,work, time, and cost accounting, consultation, and reports andother paperwork associated with that 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 seque
19、ntial ID numbers.For example, “86/0428” might identify the associated work asthe 428th request submitted in the year 1986. The Data Recordshould provide all data generated during the analyses, names ofpersons performing the analyses, dates the analyses wereperformed, and any unusual occurrences that
20、 happened duringthe analyses. Accountability for production control samples isnormally maintained separately from 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 wh
21、ich they were taken.5.3.2 Each sample, specimen, sample site, or other uniquepiece of material or container identified 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 p
22、ersonnel will markeach sample or sample container with its own laboratorysample number (ID-NN) in such manner that 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 migh
23、t beidentified as “86/0428-05.”5.3.3 All laboratory work records, intermediate samplecontainers, data, and reports 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 reque
24、sts.5.3.4 The first and last steps in the accountability procedureare functions of technical supervision. Before 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 comp
25、letedtheir work, the results must be reviewed to be certain that allinformation requested has been determined and 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 re
26、viewingsupervisor. The supervisor also verifies that the results arecalculated in units that are most meaningful 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 listi
27、ng of laboratory identificationnumbers and descriptions, and a copy of each job report areretained in the laboratorys records for the periods of timeestablished by laboratory policy. Intermediate calculations andsamples are normally discarded after the submitter has had areasonable opportunity to su
28、bmit questions concerning theresults and request return of his samples. In some cases,customer specifications may 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 th
29、einformation needed to ensure that procedures, equipment, andpersonnel are performing at the levels of precision 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
30、quality control procedures:6.2.1 Involve the operators or analysts who actually performthe work to the greatest 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 ar
31、e preferred.6.2.3 Perform the quality control measurements as early inthe measurement process as possible. This 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
32、 in controlthroughout the run.6.2.4 Provide specific action limits and describe exactlywhat must be done when these 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.
33、Any inhomo-geneity in the control sample will add to the variance of theresults. Any increase in variability that 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 sho
34、uld be similarto the samples to be analyzed. Obtain as large an amount ofcontrol material as can be prepared in 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
35、ready whenneeded. In situations where satisfactory control material cannotbe obtained, alternative techniques (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. S
36、upervision maydecide that, if the analyst can correct the problem so that thecontrol sample results are again within 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 eith
37、er case, adjustments tothe process should be recorded to explain each shift in thecontrol measurements.6.2.7 Provide for a periodic in-depth review by supervisionand management of the overall effectiveness of the laboratoryquality control system. Operating experience may indicate thatmethods should
38、be added to, or dropped from the program, thatthe frequency of specific control samples should be increasedor decreased, 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 theE882 10 (2016)12p
39、rocesses that generate the samples. Any anticipated or ob-served change in the character of the samples being analyzedshould initiate 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 sui
40、table for laboratory quality control programs.The choice of which control strategy to use depends oncircumstances: the type of 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
41、R-chart method is most frequently used.The control sample is run two or more times during the run,batch, or shift. 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
42、 and lower control limits and the range fallsbelow the upper control limit, the process is considered to be incontrol. 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 mad
43、e on afrequent or continual basis. It is appropriate for methods orinstruments for which the usual mode of failure producesrelatively large shifts in results and the cost of a determinationprecludes performing replicate analyses of control samples. Itsmain characteristic is that it responds rapidly
44、to suddenrelatively large changes in the analytical process, but it is notas sensitive to small changes as the X- 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
45、considered to be incontrol. Fig. 3 shows the essential features of charts forindividuals.6.3.3 A combination of 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
46、 or a day in a continuousanalysis process). Each individual value is plotted on theX-chart as the measurement is 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 e
47、rroneous assays would causelarge economic losses. Other control chart techniques that maybe appropriate for special 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 forinfrequentl
48、y used analytical methods or for non-routine sampletypes. If a CRM (from the National Institute of Standards andTechnology 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 con
49、fidence in the sample assays. Lacking a CRM,any previously analyzed material may be used. In all cases, itis important 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 analytical values.6.4.2 grand mean:X%5 XH11XH21 XHk!/k (2)where:FIG. 1 Control Chart for AveragesE882 10 (2016)13k = the number of individual means.6.
