1、Designation: D 6850 03Standard 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 number in parentheses
2、 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 constituents in water. Me
3、thods 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 quality of data that i
4、s 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 for Sampling Chain-
5、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. Terminology3.1 Defini
6、tionsFor 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 (group) of sampl
7、es 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 D 5847 for defin
8、ition 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 level.3.2.5 qua
9、litative 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 of thescreening
10、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-quantitative method T
11、ype 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 Type 2, na method w
12、hoseresults 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. Significance and Use4.1 S
13、creening 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 furtheraction is us
14、eful in reducing the number of negative results forwhich the screening method serves as a surrogate.1This 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 Jan. 10, 2003. Pu
15、blished January 2003.2For 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 ASTM International, 100 Barr
16、Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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, andsite characterization. The appropriate use
17、of a screeningmethod, 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 datagenerated by the use of screening methods should have detailedQuality Control guidelines
18、 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 method must allow for the nec-essary number of samples to be run in a timely manner, not to
19、exceed 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 method is necessary to eliminate thesepositive results.5.4 It is essential that an appropriate
20、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 information on establishing a SOP for a method.5.5 Issues relating to timeliness of sample collect
21、ion 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 may be necessary.5.6 When selecting a field screening method, considerationsmust be given t
22、o 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 General Considerations:6.1.1 Due to possible difficulties in performing several ofthese requir
23、ements 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, usingreagent water as described in Specification D 1193, with everybatch to verify the test will pro
24、duce 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 results meet the methods performance crite-ria.6.1.3 It is required that the analyst using
25、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 the actual matrix if possible. If not, a similarmatrix should be used. Example: Use substit
26、ute 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 in a representative matrix.6.1.5 It is recommended that all screening methods becompared to
27、 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 Specific requirements of a QC system for screeningmethods will be dependent upon the type
28、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-bration curve with standards before or during sample analysis.6.2 Qualitative Methods:6.2.1 The
29、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 produce a positive result.6.2.1.3 Establish the screening limit of the method. Ensurethe screenin
30、g 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 positive response.6.3 Semi-Quantitative Type 1 Methods:6.3.1 It is suggested all of the tests f
31、or 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 and for others it will be a calibrationverification.6.3.1.2 Perform a matrix spike; ensure th
32、e 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 for semi-quantitative Type 1 methods the precision will bereported as the number of times t
33、he 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 based onwhether the result was in the correct concentration range.Example: When running a 7
34、 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 Perform a calibration or calibration verification ofthe method.6.4.1.2 Run a matrix spike; d
35、etermine the recovery of thespike.D68500326.4.1.3 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.7. Inter-laboratory Comparison7.1 When performing an Inter-laboratory study the follo
36、w-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-Quantitative Type 1 methods define the bias as in 6.3.1.5.7.1.3 Semi-Quantitative Type 2 methods can
37、 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 control requirementsfrom Section 6 will have been run within a single laboratory.8.1.2 The method will be
38、 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 generated following this guide mustreference this guide number and report the type of methodperformed
39、 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 Information)X1. ADDITIONAL LITERATURE RESOURCEX1.1 The following literature was not reference in thisdocumen
40、t 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 respecting the validity of any patent rights asserted in connection with any item mentionedin this standar
41、d. 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 standard is subject to revision at any time by the responsible technical committee and must be reviewed
42、 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 International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible t
43、echnical 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.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).D6850033
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