1、Designation: E1726 01 (Reapproved 2009)Standard Practice forPreparation of Soil Samples by Hotplate Digestion forSubsequent Lead Analysis1This standard is issued under the fixed designation E1726; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 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.1. Scope1.1 This practice covers drying, homogenization, and aciddigestion of soil samples and associate
3、d quality control (QC)samples using a hot plate type method for the determination oflead using laboratory atomic spectrometry analysis techniquessuch as Inductively Coupled Plasma Atomic Emission Spec-trometry (ICP-AES), Flame Atomic Absorption Spectrometry(FAAS), and Graphite Furnace Atomic Absorpt
4、ion Spectrom-etry (GFAAS).1.2 This practice is based on U.S. EPA SW 846, TestMethod 3050.1.3 This practice contains notes that are explanatory and arenot part of the mandatory requirements of this standard.1.4 The values stated in SI units are to be regarded asstandard. The values given in parenthes
5、es are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.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
6、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent Water2.2 U.S. Government Analytical Method:3U.S. EPA SW 846 Test Methods for Evaluating Solid WastePhysical/Chemical
7、Methods2.3 Other Standards:4ISO Guide 30 Terms and Definitions Used in Connectionwith Reference Materials3. Terminology3.1 Definitions:3.1.1 batcha group of field or quality control (QC)samples that are processed together using the same reagentsand equipment.3.1.2 certified reference materialreferen
8、ce material ac-companied by a certificate, one or more of whose propertyvalues are certified by a procedure which establishes itstraceability to an accurate realization of the unit in which theproperty values are expressed; each certified value is accom-plished by an uncertainty at a stated level of
9、 confidence(ISO Guide 30).3.1.3 digestatean acidified aqueous solution that resultsfrom digestion of the sample.3.1.4 digestionthe sample preparation process that willsolubilize (extract) targeted analytes present in the sample andresults in an acidified aqueous solution called the digestate.3.1.4.1
10、 Discussion Digestion is a form of extraction (see3.1.6).3.1.5 duplicate samplea second portion of a homogenizedsample carried through sample digestion. Analysis results forthese samples are used to provide information on the precisionof the homogenization process.3.1.6 extractionthe dissolution of
11、target analytes from asolid matrix into a liquid form. During sample digestion, targetanalytes are extracted (solubilized) into an acid solution.3.1.7 non-spiked samplea portion of a homogenizedsample that is targeted for addition of analyte but that is notfortified (spiked) with lead before sample
12、preparation.Analysisresults for this sample are used to correct for background levelsin soil that are used for the spiked and spiked duplicatesamples.3.1.8 reagent blanka digestate that reflects the maximumtreatment given any one sample within a batch of samples,except that it has no sample initiall
13、y placed into the digestion1This practice is under the jurisdiction of ASTM Committee E06 on Perfor-mance of Buildings and is the direct responsibility of Subcommittee E06.23 on LeadHazards Associated with Buildings.Current edition approved Nov. 1, 2009. Published January 2010. Originallyapproved in
14、 1995. Last previous edition approved in 2001 as E1726 01. DOI:10.1520/E1726-01R09.2For 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 pa
15、ge onthe ASTM website.3Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/w
16、ww.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.vessel. (The same reagents and processing conditions whichare applied to field samples within a batch are also applied tothe reagent blank.)3.1.8.1 DiscussionAnalysis result
17、s from reagent blanksprovide information on the level of potential contaminationexperienced by samples processed within the batch.3.1.9 spiked samplea portion of a single homogenizedsample to which the same known amount of analyte is added(spiked) before sample digestion.3.1.9.1 DiscussionAnalysis r
18、esults for these samples areused to provide information on accuracy and precision of theoverall analysis process.4. Summary of Practice4.1 A representative soil sample is dried and homogenized,and then digested (in a batch mode with other samples) on a hotplate using nitric acid and hydrogen peroxid
19、e. The digestate isdiluted for final volume prior to lead measurement.5. Significance and Use5.1 There is a need to monitor the lead content in andaround buildings and related structures in order to determinethe potential lead hazard. Hence, effective and efficient meth-ods are required for the prep
20、aration of soil samples fordetermination of their lead content.5.2 This practice may be used for the digestion of soilsamples that are collected during various construction andrenovation activities associated with lead abatement in andaround buildings and related structures. The practice is alsosuit
21、able for the digestion of soil samples for lead analysescollected from other locations, such as near roads and steelstructures.5.3 This practice is intended to be used to prepare samplesthat have been collected for hazard assessment purposes.5.4 This practice is not capable of determining lead bound
22、within matrices, such as silica, that are not soluble in nitricacid.5.5 This practice includes drying and homogenization stepsin order to help assure that reported lead results are represen-tative of the sample and are independent of potential differ-ences in soil moisture levels among different sam
23、pling loca-tions or changing weather conditions.6. Apparatus6.1 Equipment:6.1.1 Analytical Balance, capable of accurately determiningthe mass to the nearest 0.001 g.6.1.2 Drying Oven, capable of maintaining a temperature of100 to 120C.6.1.3 Electric Hot Plate, capable of maintaining a tempera-ture o
24、f 80 to 100C as measured with a thermometer placedinto a beaker or flask filled with water sitting on the hot platehead. When required to reduce the presence of hot spots in theelectrical hot plate, placea2to2.5cm(0.75 to 1 in.) thickaluminum plate on the burner head.6.1.4 Grinding ApparatusMortar a
25、nd pestle (porcelain oragate), shatter box, or mixer mill.6.1.5 Micropipettors with Disposable Plastic Tips, sizesneeded to make reagent additions, and spiking standards (seeNote 1).NOTE 1In general, the following sizes should be readily available:15 mL adjustable, 1000, 500, 250, and 100 L.6.1.6 Si
26、eves, 4.7 mm (U.S. Standard No. 4), 1.9 mm (No.10), and 500 m (No. 35), plastic or stainless steel (see Note 2).When sieves containing soldered joints are used, then all solderjoints shall be coated with epoxy resin prior to use to protectsamples from potential lead contamination originating in thes
27、older. Visually inspect prior to use for the presence of baremetal.NOTE 2Stainless steel or plastic sieves must be used instead of thestandard brass sieves to alleviate possible lead contamination of the soilsamples from contact with lead solder common to brass sieves.6.1.7 Thermometers, red alcohol
28、, that cover a range from 0to 110C.6.2 Glassware and Supplies:6.2.1 Borosilicate GlasswareVolumetric flasks with stop-pers, 100 mL; Griffin beakers, 100, 150 or 250 mL; watchglasses sized to cover Griffin beakers.6.2.2 Plastic Gloves, powderless.6.2.3 Air-Tight Sample Containers1 L (1 qt) or 4 L (1
29、gal)re-sealable plastic bags, or plastic 50 mL centrifuge tubes.6.2.4 Volumetric FlasksClass A, 100 mL and other sizesas needed to make dilutions of sample digests or lead standardsused for fortification of spiked samples.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in this
30、practice. Unless otherwise indicated, all reagentsshall conform to the specifications for the Committee onAnalytical Reagents of the American Chemical Society, wheresuch specifications are available.5Other grades shall not beused unless it is first ascertained that the reagent is ofsufficiently high
31、 purity to permit its use without lesseningaccuracy of the determination.7.2 Nitric AcidConcentrated, suitable for atomic spec-trometry analysis, such as spectroscopic grade.7.3 Hydrogen Peroxide, 30 % (w/w), suitable for atomicspectrometry analysis such as spectroscopic grade.7.4 Acetone, reagent,
32、spectroscopic grade.7.5 WaterUnless otherwise indicated, references to watershall mean reagent water as defined by Type I of SpecificationD1193. (ASTM Type I Water: minimum resistance of 16.7megohmcm, or equivalent.)7.6 Calibration Stock Solution, 100 g/mL of lead (Pb) indilute nitric acid.8. Sample
33、 Preparation Procedure8.1 Sample Pre-Treatment:8.1.1 Treat each sample in a processing batch equally.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC, www.chemistry.org. For suggestions on thetesting of reagents not listed by the American Chemica
34、l Society, see the UnitedStates Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention,Inc. (USPC), Rockville, MD, http:/www.usp.org.E1726 01 (2009)28.1.2 If possible before removal, break up the soil samplewithin the original containers containing the samples (see Note3).NOTE 3This will
35、 not be possible for wet soil samples.8.1.3 Label an acid-cleaned 100, 150, or 250 mL Griffinbeaker (or other vessel suitable for oven drying of soils thatwill not contaminate the sample with lead) with a hightemperature wax pen or any other marker that will be visibleafter exposure to the drying ov
36、en.8.1.4 Transfer the entire soil sample to the labeled Griffinbeaker. Cover with a watch glass (tip to one side to permitmoisture removal), and place in a drying oven for a minimumof6hatatemperature of 110 6 10C (see Note 4).NOTE 4If the received soil sample is excessively large, then anyattempts t
37、o sub-sample prior to drying and sieving are likely to cause bias.If possible, use a larger beaker to contain the entire sample. If not, then usemultiple beakers followed by re-combining after drying. Samples thatcake or plug the sieve require additional drying. Soil samples should notcake or exhibi
38、t packing characteristic of moisture, but should flow freelythrough the sieve (see 8.1.6) when broken apart.8.1.5 Using tongs, remove the beakers containing thesamples and allow them to cool to room temperature.8.1.6 Don a pair of plastic gloves and push the soil samplethrough a clean 4.7 mm sieve (
39、U.S. Standard No. 4) to removeany large objects or root material, or both. Discard materialretained on the sieve (see Notes 5 and 6). Clean the sievebetween samples by tapping or using forced air or other drymethod to prevent cross-contamination. Perform this step in alocation well removed from othe
40、r samples in process and in anarea where soil dust will not contaminate the laboratoryoperations such as in front of a fume hood.NOTE 5If the samples do not appear to contain any large objects orroot material, it is not necessary to perform this step with the 4.7 mmsieve.NOTE 6In order to minimize s
41、mall particle size soil losses, this stepshould not be performed inside a fume hood.8.1.7 Don a pair of plastic gloves and push the soil samplethrough a clean 2 mm sieve (U.S. Standard No. 10) to removecoarse material (see Note 6). Discard material retained on thesieve. Clean the sieve between sampl
42、es by tapping or usingforced air or other dry method to prevent cross-contamination.Perform this step in a location well removed from othersamples in process, and in an area where soil dust will notcontaminate the laboratory operations, such as in front of afume hood.8.1.8 Grind the sample using a p
43、orcelain mortar and pestleor other appropriate homogenization apparatus such as ashatter-box or mixer mill. Clean the grinding apparatus be-tween samples to prevent cross-contamination betweensamples by rinsing with water and drying. When any materialis retained from 8.1.9, delay cleaning until this
44、 retainedmaterial for the sample is re-ground as described in 8.1.10.Anacetone rinse will facilitate drying (see Note 7).NOTE 7Acetone should not be used on sieves since it can damageepoxy coatings which may be present to seal lead solder joints.8.1.9 Place the ground up sample on a clean 500 m siev
45、e(U.S. Standard No. 35). Use a stainless steel spoon to helpmove material around until no more sample will pass throughthe sieve. Do not discard the retained material (see Note 8).Return any retained material for one more grinding as de-scribed in 8.1.8.NOTE 8A second re-grinding step is included fo
46、r retained material toavoid inadvertent loss of larger pieces of material that can remain as aresult of inadequate grinding.8.1.10 Place the ground up retained sample material back onthe clean U.S. Standard No. 35 (500 m sieve) (see Note 6).Using a stainless steel spoon, help move material around un
47、tilno more sample will pass through the sieve, adding the passedmaterial to the previous sample material that passed throughthe sieve. Discard any retained material. Clean the sievebetween samples by tapping or using forced air or other drymethod to prevent cross-contamination. Perform this step in
48、alocation well removed from the samples in process.8.1.11 Label acid-cleaned 100, 150, or 250 mL Griffinbeakers and watch glasses for performing the digestion of eachsoil sample and associated QC samples.8.1.12 Transfer sieved portion to a labeled Griffin beakerand place in a drying oven overnight o
49、r for a minimum of 12h, or to constant mass at a temperature of 110 6 10C (seeNote 9). Remove from oven and allow to cool to roomtemperature.NOTE 9Constant mass for this procedure is defined as a less than0.1 % change in mass for repeated measurements (a minimum of two)taken over a minimum ofa1hinterval.8.1.13 Store the dried, homogenized, and sieved soilsamples inside new labeled air-tight sample containers.8.2 Sample Digestion:8.2.1 Turn or roll the sample container repeatedly for about1 min. Determine the mass of each dried homogenized s
