1、Designation: D6564 00 (Reapproved 2012)1Standard Guide forField Filtration of Groundwater Samples1This standard is issued under the fixed designation D6564; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial changes were made throughout in May 2012.1. Scope1.1 This guide covers methods for field filtration of ground-water samples colle
3、cted from groundwater monitoring wells,excluding samples 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
4、purposes. Laboratoryfiltration methods are not described in this guide.1.2 This guide provides procedures available for field filtra-tion of groundwater samples. The need for sample filtration forspecific analytes should be defined prior to the sampling eventand documented in the site-specific sampl
5、ing and analysis planin accordance with Guide D5903. The decision should be madeon a parameter-specific basis with consideration of the dataquality objectives of the sampling program, any applicableregulatory agency guidelines, and analytical method require-ments.1.3 This guide offers an organized c
6、ollection of informationor a series of options and 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 int
7、ended to represent or replace thestandard of care 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 approv
8、ed through the ASTM consensusprocess.1.4 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 lim
9、itations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD5088 Practice for Decontamination of Field EquipmentUsed at Waste SitesD5092 Practice for Design and Installation of Ground WaterMonitoring WellsD5903 Guide for Planning and
10、Preparing for a GroundwaterSampling EventD6089 Guide for Documenting a Ground-Water SamplingEventF740 Definitions of Terms Relating to Filtration (Withdrawn2002)33. Terminology3.1 Definitions: For definitions of common technical termsin this standard, refer to Terminology D653.3.2 Definitions of Ter
11、ms Specific to This Standard:3.2.1 filter, vto pass a fluid containing particles through afilter medium whereby particles are separated from the fluid.F7403.2.2 filter, na device for carrying out filtration whichconsists of the combination of the filter medium and suitablehardware for constraining a
12、nd supporting it in the path of thefluid. F7403.2.3 filter mediumthe permeable material used for a filterthat separates particles from a fluid passing through it. F7403.2.4 filter preconditioningthe process of preparing a filtermedium for filtration3.2.5 filter systemthe combination of one or more f
13、ilterwith all the associated process hardware required for filtration.F7401This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved May 15, 2012. Published D
14、ecember 2012. Originallyapproved in 2000. Last previous edition approved in 2005 as D6564 00(2005).DOI: 10.1520/D6564-00R12E1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
15、 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 States13.2.6 filtratethe fluid that has pass
16、ed through the filter.F7403.2.7 filtrationthe process by which particles are sepa-rated from a fluid by passing the fluid through a permeablematerial. F7403.2.8 filtered samplea groundwater sample which haspassed through a filter medium.3.2.8.1 DiscussionThis type of sample may also be re-ferred to
17、as a “dissolved” sample. An unfiltered samplecontaining dissolved, sorbed, coprecipitated and all suspendedparticles may be referred to as a “total” sample.3.2.9 particlea small discrete mass of solid or liquidmatter. F7404. Significance and Use4.1 A properly designed, installed and developed ground
18、-water monitoring well, constructed in accordance with PracticeD5092, should facilitate collection of samples of groundwaterthat can be analyzed to determine both the physical andchemical properties of that sample. Samples collected fromthese wells that require analysis for dissolved constituentssho
19、uld be filtered in the field prior to chemical preservation andshipment to the laboratory for analysis.5. Purpose of Groundwater Sample Filtration5.1 Groundwater samples may be filtered to separate adefined fraction of the sample for analysis.6. Timing of Groundwater Sample Filtration6.1 Groundwater
20、 samples 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
21、 pressure 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 sam
22、ple with air can cause aeration andoxidation of dissolved ferrous to ferric iron. Ferric iron rapidly precipi-tates as amorphous iron hydroxide and can absorb other dissolved tracemetals (2).7. Groundwater Sample Filtration Procedures7.1 Preparation for Groundwater Sample FiltrationThegroundwater sa
23、mple filtration process consists of three phases:selection of filtration method; selection and pretreatment offilter media; and groundwater sample filtration prior to transferinto the sample container.7.1.1 Filtration Method Selection CriteriaA wide varietyof methods are available for field filtrati
24、on of groundwatersamples. In general, filtration equipment can be divided intopositive pressure filtration and vacuum (negative pressure)filtration methods, each with several different filtration mediumconfigurations. Groundwater samples undergo pressurechanges as they are brought from the saturated
25、 zone (wheregroundwater 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 preferred. Tab
26、le 1 presentsequipment options available for positive pressure and vacuumfiltration of groundwater 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:7.1.2.1 Ef
27、fect 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 constituentsresulting fro
28、m 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 orcomponents of
29、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 withgroundwater sample chemistry;7.1.2.9 Anticipated amount of suspended solids and theattendant effects of particulate loading (reduction in effectivefilter pore size);7.
30、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 area;7.1.
31、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, expendable
32、supplies and their disposal,4The 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 Groundwater SamplesPositive Pressure Filtration Equipment:In-line capsulesattached directly
33、 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 assemblyD6564 00 (2012)12time required for filtrati
34、on, 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 should be consistent throughout the lifeof the sampling program to p
35、ermit 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 oncomparability of data
36、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 ConstructionFiltra
37、tion 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 negative bias
38、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) and7.1.3.4 Aeratio
39、n of the sample leading to precipitation ofsome constituents (for example, ferric hydroxide) (3).7.1.4 Selection and Pretreatment of Filter MediaFiltrationmedia are manufactured with specific pore size diametersdesigned to permit particles of a selected size to be retained bythe filter medium. Filtr
40、ation media must be selected afterconsidering filter pore size, and materials of construction.Groundwater 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 Filtration M
41、edium: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 uniform wetting fr
42、ont 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 cases, filter
43、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.NOTE 5Some f
44、ilters 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), the mater
45、ial 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 proper methods
46、 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 to damage du
47、ring handling.FIG. 1 Examples of Common Filter Characteristics and ApplicationsD6564 00 (2012)13Therefore, 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 p
48、reconditioned as follows:7.1.6.1 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 should not
49、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-specific 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;
