1、Designation: D 6564 00 (Reapproved 2005)Standard Guide forField Filtration of Ground-Water Samples1This standard is issued under the fixed designation D 6564; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number 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 methods for field filtration of ground-water samples collected from ground-water monitoring wells,excluding sam
3、ples that contain non-aqueous phase liquids(either Dense Non-Aqueous Phase Liquids (DNAPLs) or LightNon-Aqueous Phase Liquids (LNAPLs). Methods of fieldfiltration described herein could also be applied to samplescollected from wells used for other purposes. Laboratoryfiltration methods are not descr
4、ibed in this guide.1.2 This guide provides procedures available for field filtra-tion of ground-water samples. The need for sample filtrationfor specific analytes should be defined prior to the samplingevent and documented in the site-specific sampling and analy-sis plan in accordance with Guide D 5
5、903. The decision shouldbe made on a parameter-specific basis with consideration of thedata quality objectives of the sampling program, any applicableregulatory agency guidelines, and analytical method require-ments.1.3 This guide offers an organized collection of informationor a series of options a
6、nd does not recommend a specific courseof action. This guide cannot replace education or experienceand should be used in conjunction with professional judgment.Not all aspects of this guide may be applicable in all circum-stances. This guide is not intended to represent or replace thestandard of car
7、e by which the adequacy of a given professionalservice must be judged, nor should this guide be appliedwithout consideration of the many unique aspects of a project.The word “Standard” in the title of this guide means only thatthe guide has been approved through the ASTM consensusprocess.1.4 This st
8、andard 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
9、 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 5088 Practice for Decontamination of Field EquipmentUsed at Non-Radioactive Waste SitesD 5092 Practice for Design and Installation of Ground-Water Monitoring Wells in AquifersD 5903 Guide for Planning and Preparing for a
10、 Ground-Water Sampling EventD 6089 Guide for Documenting a Ground-Water SamplingEventF 740 Terminology Relating to Filtration33. Terminology3.1 filter, vto pass a fluid containing particles through afilter medium whereby particles are separated from the fluid.F 7403.2 filter, na device for carrying
11、out filtration whichconsists of the combination of the filter medium and suitablehardware for constraining and supporting it in the path of thefluid. F 7403.3 filter mediumthe permeable material used for a filterthat separates particles from a fluid passing through it. F 7403.4 filter preconditionin
12、gthe process of preparing a filtermedium for filtration3.5 filter systemthe combination of one or more filter withall the associated process hardware required for filtration.F 7403.6 filtratethe fluid that has passed through the filter.F 7403.7 filtrationthe process by which particles are separatedf
13、rom a fluid by passing the fluid through a permeable material.F 7401This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.21 on Ground Water andVadose Zone Investigations.Current edition approved Nov. 1, 2005. Published Decembe
14、r 2005. Originallyapproved in 2000. Last previous edition approved in 2000 as D 6564 00.2For 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 Summa
15、ry page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.8 filtered samplea ground-water sample which haspassed through a filter medium.3.8.1 DiscussionThis type of sample may also be referredto as a “d
16、issolved” sample. An unfiltered sample containingdissolved, sorbed, coprecipitated and all suspended particlesmay be referred to as a “total” sample.3.9 particlea small discrete mass of solid or liquid matter.F 7404. Significance and Use4.1 A properly designed, installed and developed ground-water m
17、onitoring well, constructed in accordance with PracticeD 5092, should facilitate collection of samples of ground waterthat can be analyzed to determine both the physical andchemical properties of that sample. Samples collected fromthese wells that require analysis for dissolved constituentsshould be
18、 filtered in the field prior to chemical preservation andshipment to the laboratory for analysis.5. Purpose of Ground-Water Sample Filtration5.1 Ground-water samples may be filtered to separate adefined fraction of the sample for analysis.6. Timing of Ground-Water Sample Filtration6.1 Ground-water s
19、amples should be filtered immediatelyupon collection and prior to chemical preservation of thesample. (1)4Filtration should be completed in as short a timeas possible while minimizing sample aeration, agitation, pres-sure changes, temperature changes and prolonged contact withambient air.NOTE 1The p
20、ressure change that occurs when the sample is broughtto the surface may cause changes in sample chemistry which includelosses of dissolved gases and precipitation of dissolved constituents suchas metals. When handling samples during filtration operations, additionalturbulence and mixing of the sampl
21、e with air can cause aeration andoxidation of dissolved ferrous to ferric iron. Ferric iron rapidly precipi-tates as amorphous iron hydroxide and can adsorb other dissolved tracemetals (2).7. Ground-Water Sample Filtration Procedures7.1 Preparation for Ground-Water Sample FiltrationTheground-water s
22、ample filtration process consists of three phases:selection of filtration method; selection and pretreatment offilter media; and ground-water sample filtration prior to trans-fer into the sample container.7.1.1 Filtration Method Selection CriteriaA wide varietyof methods are available for field filt
23、ration of ground-watersamples. In general, filtration equipment can be divided intopositive pressure filtration and vacuum (negative pressure)filtration methods, each with several different filtration mediumconfigurations. Ground-water samples undergo pressurechanges as they are brought from the sat
24、urated zone (whereground water is under pressure greater than atmospheric) to thesurface (where it is under atmospheric pressure), resulting inchanges in sample chemistry. Vacuum filtration methods fur-ther exacerbate pressure changes. For this reason, positivepressure filtration methods are preferr
25、ed. Table 1 presentsequipment options available for positive pressure and vacuumfiltration of ground-water samples. Fig. 1 presents examples ofcommon filter characteristics and applications.7.1.2 When selecting a filtration method, the followingcriteria should be evaluated on a site-by-site basis:7.
26、1.2.1 Effect on sample integrity considering the potentialfor the following to occur:7.1.2.2 Sample aeration (Note 2),7.1.2.3 Sample agitation (Note 2),NOTE 2Sample aeration and increased agitation may result in samplechemical alteration.7.1.2.4 Change in partial pressure of sample constituentsresul
27、ting from application of negative pressure to the sampleduring filtration,7.1.2.5 Sorptive losses of components from the sample ontothe filter medium or components of the filtration equipment(for example, flasks, filter holders etc.); and7.1.2.6 Leaching of components from the filter medium orcompon
28、ents of the filtration equipment into the sample.7.1.2.7 Volume of sample to be filtered;7.1.2.8 Chemical compatibility of filter medium withground water sample chemistry;7.1.2.9 Anticipated amount of suspended solids and theattendant effects of particulate loading (reduction in effectivefilter pore
29、 size);7.1.2.10 Time required to filter samples (Note 3);NOTE 3Short filtration times are recommended to minimize the timeavailable for chemical changes to occur in the sample.7.1.2.11 Ease of use;7.1.2.12 Availability of an appropriate medium in the de-sired filter pore size7.1.2.13 Filter surface
30、area;7.1.2.14 Use of disposable versus non-disposable equip-ment;7.1.2.15 Ease of cleaning equipment if not disposable;7.1.2.16 Potential for sample bias associated with ambientair contact during sample filtration; and7.1.2.17 Cost, evaluating the costs associated with: equip-ment purchase price, ex
31、pendable supplies and their disposal,time required for filtration, time required for decontaminationof non-disposable equipment and quality control measures.7.1.2.18 The filtration method used for any given samplingprogram should be documented in the site-specific samplingand analysis plan and shoul
32、d be consistent throughout the life4The boldface numbers given in parentheses refer to a list of references at theend of the text.TABLE 1 Examples of Equipment Options for Positive andNegative Pressure Filtration of Ground Water SamplesPositive Pressure Filtration Equipment:In-line capsulesattached
33、directly to a pumping device discharge hoseattached to a pressurized transfer vesselattached to a pressurized bailerFree-standing disk filter holdersSyringe filtersZero headspace extraction vesselsNegative Pressure Filtration Equipment:Glass funnel support assemblyD 6564 00 (2005)2of the sampling pr
34、ogram to permit comparison of data gener-ated. If an improved method of filtration is determined to beappropriate for a sampling program, the sampling and analysisplan should be revised and implemented in lieu of continuationof the existing filtration method. In this event, the effect oncomparabilit
35、y of data needs to be examined and quantified toallow proper data analysis and interpretation (Note 4).NOTE 4Statistical methods may need to be implemented to determinethe significance of any changes in data resulting from a change in filtrationmethod.7.1.3 Filtration Equipment Materials of Construc
36、tionFiltration equipment and filtration media are available in awide variety of materials of construction. Materials of con-struction should be evaluated (for example, by contactingmanufacturers, conducting leach tests or collecting equipmentblanks) to minimize sample bias:7.1.3.1 Potential for nega
37、tive bias due to adsorption ofconstituents from the sample (2);7.1.3.2 Potential for positive bias due to desorption orleaching of constituents into the sample (3-6);7.1.3.3 Reduction of the effective filter pore size caused byclogging when filtering water containing suspended particles;(6) and7.1.3
38、.4 Aeration of the sample leading to precipitation ofsome constituents (for example, ferric hydroxide) (3).7.1.4 Selection and Pretreatment of Filter MediaFiltration media are manufactured with specific pore sizediameters designed to permit particles of a selected size to beretained by the filter me
39、dium. Filtration media must be selectedafter considering filter pore size, and materials of construction.Ground-water samples requiring field filtration must be filteredusing a medium with a pore size that meets the requirements ofthe approved sampling and analysis plan.7.1.5 Preconditioning of the
40、Filtration Medium:7.1.5.1 Filter media require preconditioning prior to samplefiltration (7). Purposes of filter preconditioning include: tominimize positive sample bias associated with residues thatmay exist on the filter surface or constituents that may leachfrom the filter; and to create a unifor
41、m wetting front across theentire surface of the filter to prevent channel flow through thefilter and increase the efficiency of the filter surface area.Preconditioning the filter medium may not completely preventsorptive losses from the sample as it passes through the filtermedium.7.1.5.2 In most ca
42、ses, filter preconditioning should be doneat the wellhead (Note 5) immediately prior to use. Somemanufacturers prerinse filters prior to sale. These filters aretypically marked “prerinsed” on filter packaging and providedirections for any additional field preconditioning requiredprior to filter use.
43、NOTE 5Some filters require preconditioning procedures that can onlybe done in the laboratory (for example, GF/F filters must be baked priorto use).7.1.5.3 The procedure used to precondition the filter me-dium is determined by the following: the design of the filter(that is, filter capsules, or disks
44、), the material of construction ofthe filter medium, the configuration of the filtration equipment,and the parameters of concern for sample analysis. Filtrationmedium manufacturers instructions should be followed priorto implementing any filter preconditioning protocols in thefield to ensure that pr
45、oper methods are employed and tominimize potential bias of samples being filtered.7.1.5.4 The volume of water used in filter preconditioning isdependent upon the surface area of the filter and the mediumsability to absorb liquid. Many filter media become fragile whensaturated and are highly subject
46、to damage during handling.Therefore, saturated filter media should be handled carefullyand are best preconditioned immediately prior to use.7.1.6 Preconditioning of Disk FiltersDisk filters (alsoknown as plate filters) should be preconditioned as follows:FIG. 1 Examples of Common Filter Characterist
47、ics and ApplicationsD 6564 00 (2005)37.1.6.1 Hold the edge of the filter with filter forceps con-structed of materials that are appropriate for the analytes ofinterest (Note 6);NOTE 6Manufacturers often use colored parchment paper disks (forexample, yellow or blue) to separate filter disks and these
48、 should not beconfused with the filtration medium.7.1.6.2 Saturate the entire filter disk with water (Note 7)(while holding the filter over a containment vessel (not thesample bottle or filter holder) to catch all run-off, then;NOTE 7Filter manufacturers should be consulted to determine filter-speci
49、fic volumes of water or medium-specific aqueous solution to be usedfor optimum filter preconditioning.7.1.6.3 Place the saturated filter on the appropriate filterstand or holder in preparation for sample filtration;7.1.6.4 Complete assembly of the filtration apparatus;7.1.6.5 Pass recommended volume of water through thefilter to complete preconditioning;7.1.6.6 Discard preconditioning water;7.1.6.7 Begin sample filtration using a clean filtration con-tainment vessel or flask.7.1.6.8 When preconditioning disk filters, care should betaken not to perforate the
