1、Designation: D 6850 03 (Reapproved 2008)Standard Guide forQC of Screening Methods in Water1This standard is issued under the fixed designation D 6850; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers general considerations for the QualityControl practices for use with screening methods for organicand inorganic constit
3、uents in water. Methods are provided byvarious standard setting bodies, governmental agencies, as wellas many domestic and international manufacturers.1.2 This guide provides general QC procedures that areapplicable to a broad range of screening methodologies. Theseprocedures help to ensure the qual
4、ity of data that is generated.Additional, method-specific or project specific requirementsmay be necessary. This guide also includes general consider-ations regarding proper utilization of screening methods.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 4840 Guide f
5、or Sample Chain-of-Custody ProceduresD 5172 Guide for Documenting the Standard OperatingProcedures Used for the Analysis of WaterD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD 5905 Practice for the Preparation of Substitute Wastewa-ter3. Termi
6、nology3.1 DefinitionsFor definitions of terms used in this guide,refer to Terminology D 1129 and Practice D 5847.3.2 Definitions of Terms Specific to This Standard:3.2.1 action level, na concentration of the analyte ofconcern at which some further action is required or suggested.3.2.2 batch, na set
7、(group) of samples analyzed such thatresults of analysis of the QC samples analyzed with the batchare indicative of the quality of the results of analysis of samplesin the batch. The number of samples in the batch is defined bythe task group responsible for the method.3.2.2.1 DiscussionSee Practice
8、D 5847 for definition anddiscussion of batch and batch size.3.2.3 false negative, na negative response for a samplethat contains the target analyte(s) at or above the stated actionlevel.3.2.4 false positive, na positive response for a sample thatcontains the target analyte(s) below the stated action
9、 level.3.2.5 qualitative method, na validated method that detectspresence or absence of an analyte at a specified screening limit.3.2.6 screening limit, nthe concentration of analyte thatcan be determined with a given certainty. The task groupresponsible for the method establishes the determination
10、of thescreening limit.3.2.7 screening method, na method that is used to sepa-rate or categorize samples.3.2.7.1 DiscussionAn example would be a method thatprovides results that would be used to separate samples intothose that contain an analyte above or below a specified actionlevel.3.2.8 semi-quant
11、itative method Type 1, na method whoseresults are given in specified, discreet concentration ranges.3.2.8.1 DiscussionTwo types of examples of this wouldinclude semi-quantitative immunoassays or test strips. Thecutoff concentration of the ranges has been predefined.3.2.9 semi-quantitative method Typ
12、e 2, na method whoseresults are reported as a single number along with the stateduncertainty.3.2.9.1 DiscussionThe uncertainty will be reported as(standard deviation of x at a concentration of y). The values ofx and y can be established from the Initial Demonstration ofPerformance study.4. Significa
13、nce and Use4.1 Screening methods are often used to determine thepresence or absence of a specific analyte, groups of analytes,classes of compounds or other indicators of chemical com-pounds in order to determine if further analysis or action isnecessary. The determination whether to proceed with fur
14、theraction is useful in reducing the number of negative results forwhich the screening method serves as a surrogate.4.2 The use of screening methods, whether to generatequalitative or semi-quantitative results, is increasingly becom-ing a useful tool for regulatory monitoring, process control, andsi
15、te characterization. The appropriate use of a screening1This guide is under the jurisdiction of ASTM Committee D19 on Water and isthe direct responsibility of Subcommittee D19.05 on Inorganic Constituents inWater.Current edition approved May 1, 2008. Published May 2008. Originallyapproved in 2003. L
16、ast previous edition approved in 2003 as D 6850 03.2For 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 ASTM website.1Copyright
17、 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.method, or any other method for that matter, is dependent uponthe Data Quality Objectives (DQOs) that are defined by theuser of the data.4.3 Persons responsible for assessing the quality of the d
18、atagenerated by the use of screening methods should have detailedQuality Control guidelines by which to assess data quality.5. Consideration for Selection of an AppropriateScreening Method5.1 The screening method chosen must be appropriate forthe Action Level of the project.5.2 The chosen screening
19、method must allow for the nec-essary number of samples to be run in a timely manner, not toexceed the storage limits of the sample as defined by themethod.5.3 Many screening methods will give a positive result forseveral compounds or class of compounds. It must be deter-mined if a more specific meth
20、od is necessary to eliminate thesepositive results.5.4 It is essential that an appropriate documentation systembe established. A Standard Operating Procedure (SOP) for thescreening method containing the appropriate QC elementsfrom this guide must be available. See Guides D 4840 andD 5172 for informa
21、tion on establishing a SOP for a method.5.5 Issues relating to timeliness of sample collection andanalysis should be considered when selecting an appropriatescreening method. For example, for analyses that must be runimmediately following sample collection, a method capable ofbeing run in the field
22、may be necessary.5.6 When selecting a field screening method, considerationsmust be given to the expected field conditions. Factors such ashumidity, power requirements, temperature, effects of ambientlighting, etc must be addressed.6. Structure of a Quality Control System for ScreeningMethods6.1 Gen
23、eral Considerations:6.1.1 Due to possible difficulties in performing several ofthese requirements in the field it is acceptable to perform thoseQC requirements in the laboratory.6.1.2 The following are suggested at a minimum for ongo-ing QC.6.1.2.1 Run a method blank containing no analyte, usingreag
24、ent water as described in Specification D 1193, with everybatch to verify the test will produce a negative result.6.1.2.2 Run a standard or set of standards with every batch.This may also serve as the calibration verification.6.1.2.3 Run a sample duplicate with every batch. Ensurethat the replicate
25、results meet the methods performance crite-ria.6.1.3 It is required that the analyst using the screeningmethod proves their proficiency with the test. The task groupresponsible for the method will establish proficiency require-ments.6.1.4 When performing matrix evaluations it is recom-mended to use
26、the actual matrix if possible. If not, a similarmatrix should be used. Example: Use substitute wastewater, asdescribed in Practice D 5905, for a wastewater matrix. Thiswill determine the suitability of the method in the matrix ofinterest. It is also suggested a laboratory control sample (LCS)be run
27、in a representative matrix.6.1.5 It is recommended that all screening methods becompared to a reference method to provide further detail of thescreening methods capabilities and limitations. This is usefulwhen establishing or verifying false positives/ negatives andrecoveries in actual samples.6.1.6
28、 Specific requirements of a QC system for screeningmethods will be dependent upon the type of analysis beingperformed.6.1.7 Semi-quantitative Type 2 methods require either pre-paring a user-generated calibration curve prior to runninganalyses, or verifying the manufacturers pre-programmed cali-brati
29、on curve with standards before or during sample analysis.6.2 Qualitative Methods:6.2.1 The following tests are recommended.6.2.1.1 Run a method blank containing no analyte to verifythe test will produce a negative result.6.2.1.2 Run a standard of the analyte of interest to verify thetest will produc
30、e a positive result.6.2.1.3 Establish the screening limit of the method. Ensurethe screening limit is below the action level of interest.6.2.1.4 If possible run a representative matrix without thetarget analyte and verify a negative response. Spike the samplewith the target analyte and verify a posi
31、tive response.6.3 Semi-Quantitative Type 1 Methods:6.3.1 It is suggested all of the tests for qualitative methodsare performed plus these additional analyses.6.3.1.1 Run standards that have concentrations at the pre-defined concentration cutoffs. For some methods this will serveas the calibration an
32、d for others it will be a calibrationverification.6.3.1.2 Perform a matrix spike; ensure the results are in theappropriate concentration range.6.3.1.3 Perform a false positive/ false negative study at allof the concentrations of interest.6.3.1.4 Perform a precision study. When performing preci-sion
33、for semi-quantitative Type 1 methods the precision will bereported as the number of times the result was in the samerange. Example: 8 of 9 replicates fell in the concentration rangeof 5 to 10 ppm.6.3.1.5 Perform a bias study. When performing bias forSemi-Quantitative Type 1 methods the bias will be
34、based onwhether the result was in the correct concentration range.Example: When running a 7 ppm standard the result was in therange of 5 to 10 ppm.6.4 Semi-Quantitative Type 2 Methods:6.4.1 It is suggested all of the tests for qualitative methodsare performed plus these additional analyses.6.4.1.1 P
35、erform a calibration or calibration verification ofthe method.6.4.1.2 Run a matrix spike; determine the recovery of thespike.6.4.1.3 Run a set of standards to determine the bias of themethod.6.4.1.4 Perform a precision study. This will establish theuncertainty that is reported in the final result.D
36、6850 03 (2008)27. Inter-laboratory Comparison7.1 When performing an Inter-laboratory study the follow-ing should be considered.7.1.1 When determining precision for qualitative and Semi-Quantitative Type 1 methods define the precision as in 6.3.1.4.7.1.2 When performing bias for qualitative and Semi-
37、Quantitative Type 1 methods define the bias as in 6.3.1.5.7.1.3 Semi-Quantitative Type 2 methods can typically beevaluated as quantitative methods.8. Screening Method Validation8.1 A validated screening method will have had the follow-ing analyses performed.8.1.1 All of the appropriate quality contr
38、ol requirementsfrom Section 6 will have been run within a single laboratory.8.1.2 The method will be run using an independent refer-ence material (IRM).8.1.3 The method will be compared to a reference method.8.1.4 An inter-laboratory study will be performed.9. Reporting Results9.1 All data that is g
39、enerated following this guide mustreference this guide number and report the type of methodperformed as described in 3.2 (that is, qualitative, semi-quantitative Type 1, semi-quantitative Type 2).10. Keywords10.1 qualitative; quality control; screening;semi-quantitativeAPPENDIX(Nonmandatory Informat
40、ion)X1. ADDITIONAL LITERATURE RESOURCEX1.1 The following literature was not reference in thisdocument but is valuable for additional information on thissubject.X1.1.1 Guide to Method Flexibility and Approval of EPAWater Methods, Draft Guide, December, 1996.ASTM International takes no position respec
41、ting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This sta
42、ndard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Internati
43、onal Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below
44、.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 6850 03 (2008)3
