ASTM_D_4841_-_88_2013e1.pdf

Designation:D484188(Reapproved 2013)1Standard Practice forEstimation of Holding Time for Water Samples ContainingOrganic and Inorganic Constituents1This standard is issued under the fixed designation D4841;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 indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEEditorial corrections made throughout in August 2013.1.Scope1.1 This practice covers the means of estimating the periodof time during which a water sample can be stored aftercollection and preservation without significantly affecting theaccuracy of analysis.1.2 The maximum holding time is dependent upon thematrix used and the specific analyte of interest.Therefore,water samples from a specific source must be tested todetermine the period of time that sample integrity is maintainedby standard preservation practices.1.3 In the event that it is not possible to analyze the sampleimmediately at the time of collection,this practice does notprovide information regarding degradation of the constituent ofinterest or changes in the matrix that may occur from the timeof sample collection to the time of the initial analysis.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits(Withdrawn 2003)3D1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3694 Practices for Preparation of Sample Containers andfor Preservation of Organic ConstituentsD4210 Practice for Intralaboratory Quality Control Proce-dures and a Discussion on Reporting Low-Level Data(Withdrawn 2002)3D4375 Practice for Basic Statistics in Committee D19 onWaterE178 Practice for Dealing With Outlying Observations3.Terminology3.1 DefinitionsFor definitions of terms used in thispractice,refer to Terminology D1129.3.1.1 criterion of detectionthe minimum quantity thatmust be observed before it can be stated that a substance hasbeen discerned with an acceptable probability that the state-ment is true(see Practice D4210).3.2 Definitions of Terms Specific to This Standard:3.2.1 maximum holding timethe maximum period of timeduring which a properly preserved sample can be stored beforesuch degradation of the constituent of interest or change insample matrix occurs that the systematic error exceeds the99%confidence interval(not to exceed 15%)of the testcalculated around the mean concentration found at zero time.3.2.2 acceptable holding timeany period of time less thanor equal to the maximum holding time.4.Summary of Practice4.1 Holding time is estimated by means of replicate analy-ses at discrete time intervals using a large volume of a watersample that has been properly collected and preserved.Asufficient number of replicate analyses are performed to main-tain the 99%confidence interval within 15%of the concen-tration found at zero time.Concentration of the constituent of1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.02 on Quality Systems,Specification,and Statistics.Current edition approved Jan.1,2013.Published January 2013.Originallyapproved in 1988.Last previous edition approved in 2008 as D4841 88(2008).DOI:10.1520/D4841-88R13E01.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 interest is plotted versus time.The maximum holding time isthe period of time from sample collection to such time thatdegradation of the constituent of interest or change in samplematrix occurs and the systematic error exceeds the 99%confidence interval(not to exceed 15%)of the test calculatedaround the mean concentration at zero time.Prior to thedetermination of holding time,each laboratory must generateits own precision data in matrix water.These data are comparedto the pooled single-operator precision data on reagent waterreported in the test method and,the less precise of the two setsof data are used in the calculation.NOTE1This practice generates only limited data wh