1、Designation: D6850 13D6850 18Standard Guide forQC of Screening Methods in Water1This standard is issued under the fixed designation D6850; 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 paren
2、theses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This guide covers general considerations for the Quality Control quality control (QC) practices for use with screeningmethods for organic and inorgan
3、ic constituents in water. Methods are provided by various standard setting bodies, governmentalagencies, as well as many domestic and international manufacturers.1.2 This guide provides general QC procedures that are applicable to a broad range of screening methodologies. Theseprocedures help to ens
4、ure the quality of data that is generated. Additional, method-specific or project specific requirements maybe necessary. This guide also includes general considerations regarding proper utilization of screening methods.1.3 The values stated in SI units are to be regarded as standard. No other units
5、of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine
6、 theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issue
7、dby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD4840 Guide for Sample Chain-of-Custody ProceduresD5172 Guide for Documenting the Standard Operating Procedu
8、res Used for the Analysis of WaterD5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water AnalysisD5905 Practice for the Preparation of Substitute Wastewater3. Terminology3.1 DefinitionsDefinitions: For definitions of terms used in this guide, refer to Terminolo
9、gy D1129 and Practice D5847.3.1.1 For definitions of terms used in this standard, refer to Terminology D1129 and Practice D5847.3.2 Definitions of Terms Specific to This Standard:3.2.1 action level, na concentration of the analyte of concern at which some further action is required or suggested.3.2.
10、2 batch, na set (group) of samples analyzed along with QC samples; the quality of the sample-sets results is indicatedby the results from the QC samples.3.2.2.1 DiscussionThe number of samples in the batch is defined by the task group responsible for the method. See Practice D5847 for definition and
11、discussion of batch and batch size.3.2.3 false negative, na negative response for a sample that contains the target analyte(s) at or above the stated action level.1 This guide is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.05 on Inorgani
12、c Constituents in Water.Current edition approved Aug. 1, 2013May 1, 2018. Published August 2013May 2018. Originally approved in 2003. Last previous edition approved in 20082013 asD6850 03 (2008).D6850 13. DOI: 10.1520/D6850-13.10.1520/D6850-18.2 For referencedASTM standards, visit theASTM website, w
13、ww.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of w
14、hat changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered t
15、he official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.4 false positive, na positive response for a sample that contains the target analyte(s) below th
16、e stated action level.3.2.5 qualitative method, na validated method that detects presence or absence of an analyte at a specified screening limit.3.2.6 screening limit, nthe concentration of analyte that can be determined with a given certainty.3.2.6.1 DiscussionThe task group responsible for the me
17、thod establishes the value of the screening limit.3.2.7 screening method, na method that is used to separate or categorize samples.3.2.7.1 DiscussionAn example would be a method that provides results that would be used to separate samples into: (1) those that contain an analyteand (2) those that do
18、not contain and analyte above or below a specified action level.3.2.8 semi-quantitative method Type 1, na method whose results are given in specified, discreet concentration ranges.3.2.8.1 DiscussionTwo types of examples of this method would include semi-quantitative immunoassays or test strips. The
19、 cutoff concentration ofthe ranges has been predefined.3.2.9 semi-quantitative method Type 2, na method whose results 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 o
20、f x and y can be established fromthe Initial Demonstration of Performance study.4. Significance and Use4.1 Screening methods are often used to determine the presence or absence of a specific analyte, groups of analytes, classes ofcompounds or other indicators of chemical compounds in order to determ
21、ine if further analysis or action is necessary. Thedetermination whether to proceed with further action is useful in reducing the number of negative results for which the screeningmethod serves as a surrogate.4.2 The use of screening methods, whether to generate qualitative or semi-quantitative resu
22、lts, is increasingly becoming a usefultool for regulatory monitoring, process control, and site characterization. The appropriate use of a screening method, or any othermethod for that matter, is dependent upon the Data Quality Objectivesdata quality objectives (DQOs) that are defined by the userof
23、the data.4.3 Persons responsible for assessing the quality of the data generated by the use of screening methods should have detailedQuality Control QC guidelines by which to assess data quality.5. Consideration for Selection of an Appropriate Screening Method5.1 The screening method chosen must be
24、appropriate for the Action Level of the project.5.2 The chosen screening method must allow for the necessary number of samples to be run in a timely manner, not to exceedthe storage limits of the sample as defined by the method.5.3 Many screening methods will give a positive result for several compo
25、unds or class of compounds. It must be determinedif a more specific method is necessary to eliminate these positive results.5.4 It is essential that an appropriate documentation system be established. A Standard Operating Procedurestandard operatingprocedure (SOP) for the screening method containing
26、 the appropriate QC elements from this guide must be available. See GuidesD4840 and D5172 for information on establishing a SOP for a method.5.5 Issues relating to timeliness of sample collection and analysis should be considered when selecting an appropriate screeningmethod. For example, for analys
27、es that must be run immediately following sample collection, a method capable of being run inthe field may be necessary.5.6 When selecting a field screening method, considerations must be given to the expected field conditions. Factors such ashumidity, power requirements, temperature, effects of amb
28、ient lighting, etcetc., must be addressed.D6850 1826. Structure of a Quality Control System for Screening Methods6.1 General Considerations:6.1.1 Due to possible difficulties in performing several of these requirements in the field it is acceptable to perform those QCrequirements in the laboratory.6
29、.1.2 The following are suggested at a minimum for ongoing QC.6.1.2.1 Run a method blank containing no analyte, using reagent water as described in Specification D1193, with every batchto verify the test will produce a negative result.6.1.2.2 Run a standard or set of standards with every batch. This
30、may also serve as the calibration verification.6.1.2.3 Run a sample duplicate with every batch. Ensure that the replicate results meet the methods performance criteria.6.1.3 It is required that the analyst using the screening method proves their proficiency with the test. The task group responsiblef
31、or the method will establish proficiency requirements.6.1.4 When performing matrix evaluations it is recommended to use the actual matrix if possible. If not, a similar matrix shouldbe used. Example: Use substitute wastewater, as described in Practice D5905, for a wastewater matrix. This will determ
32、ine thesuitability of the method in the matrix of interest. It is also suggested a laboratory control sample (LCS) be run in a representativematrix.6.1.5 It is recommended that all screening methods be compared to a reference method to provide further detail of the screeningmethods capabilities and
33、limitations. This is useful when establishing or verifying false positives/negatives and recoveries in actualsamples.6.1.6 Specific requirements of a QC system for screening methods will be dependent upon the type of analysis being performed.6.1.7 Semi-quantitative Type 2 methods require either prep
34、aring a user-generated calibration curve prior to running analyses,or verifying the manufacturers pre-programmed calibration 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 ver
35、ify the test will produce a negative result.6.2.1.2 Run a standard of the analyte of interest to verify the test will produce a positive result.6.2.1.3 Establish the screening limit of the method. Ensure the screening limit is below the action level of interest.6.2.1.4 If possible run a representati
36、ve matrix without the target analyte and verify a negative response. Spike the sample withthe target analyte and verify a positive response.6.3 Semi-Quantitative Type 1 Methods:6.3.1 It is suggested all of the tests for qualitative methods are performed plus these additional analyses.6.3.1.1 Run sta
37、ndards that have concentrations at the predefined concentration cutoffs. For some methods this will serve as thecalibration and for others it will be a calibration verification.6.3.1.2 Perform a matrix spike; ensure the results are in the appropriate concentration range.6.3.1.3 Perform a false posit
38、ive/false negative study at all of the concentrations of interest.6.3.1.4 Perform a precision study. When performing precision for semi-quantitative Type 1 methods the precision will bereported as the number of times the result was in the same range. Example: 8 of 9 replicates fell in the concentrat
39、ion range of 5to 10 ppm.6.3.1.5 Perform a bias study. When performing bias for Semi-Quantitativesemi-quantitative Type 1 methods the bias will bebased on whether the result was in the correct concentration range. Example: When running a 7 ppm standard the result was inthe range of 5 to 10 ppm.6.4 Se
40、mi-Quantitative Type 2 Methods:6.4.1 It is suggested all of the tests for qualitative methods are performed plus these additional analyses.6.4.1.1 Perform a calibration or calibration verification of the method.6.4.1.2 Run a matrix spike; determine the recovery of the spike.6.4.1.3 Run a set of stan
41、dards to determine the bias of the method.6.4.1.4 Perform a precision study. This will establish the uncertainty that is reported in the final result.7. Inter-laboratory Comparison7.1 When performing an Inter-laboratory study the following should be considered.7.1.1 When determining precision for qu
42、alitative and Semi-Quantitativesemi-quantitative Type 1 methods define the precisionas in 6.3.1.4.7.1.2 When performing bias for qualitative and Semi-Quantitativesemi-quantitative Type 1 methods define the bias as in 6.3.1.5.7.1.3 Semi-QuantitativeSemi-quantitative Type 2 methods can typically be ev
43、aluated as quantitative methods.8. Screening Method Validation8.1 A validated screening method will have had the following analyses performed.8.1.1 All of the appropriate quality control QC requirements from Section 6 will have been run within a single laboratory.D6850 1838.1.2 The method will be ru
44、n using an independent reference 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 must reference this guide number and report the type of method performedas
45、 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 this document
46、 but is valuable for additional information on this subject.X1.1.1 Guide to Method Flexibility and Approval of EPA Water Methods, Draft Guide, December, 1996.SUMMARY OF CHANGESCommittee D19 has identified the location of selected changes to this standard since the last issue (D6850 03(2008)D6850 13)
47、 that may impact the use of this standard. (Approved May 1, 2018Aug. 1, 2013.).)(1) Added 1.3 and 1.4.(1) Revised Section 3. to update format.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of thi
48、s 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 every five yea
49、rs 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 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.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO
