1、Designation: E 1726 01Standard Practice forPreparation of Soil Samples by Hotplate Digestion forSubsequent Lead Analysis1This standard is issued under the fixed designation E 1726; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e year of last revision. 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 practice covers drying, homogenization, and aciddigestion of soil samples and associated quality contr
3、ol (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 Absorption Spectrom-et
4、ry (GFAAS).1.2 This practice is based on U.S. EPA SW846Method 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 as thestandard. The inch-pound units given in parentheses are f
5、orinformation only.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
6、use.2. Referenced Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water22.2 U.S. Government Analytical Method:U.S. EPA SW 846 Test Methods for Evaluating Solid WastePhysical/Chemical Methods32.3 Other Standards:ISO Guide 30 Terms and Definitions Used in Connectionwith Reference Material
7、s43. 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 digestatean acidified aqueous solution that resultsfrom digestion of the sample.3.1.3 digestionthe sample preparation process that willsol
8、ubilize (extract) targeted analytes present in the sample andresults in an acidified aqueous solution called the digestate.Discussion: Digestion is a form of extraction (see 3.1.5).3.1.4 duplicate samplea second portion of a homogenizedsample carried through sample digestion. Analysis results forthe
9、se samples are used to provide information on the precisionof the homogenization process.3.1.5 extractionthe dissolution of target analytes from asolid matrix into a liquid form. During sample digestion, targetanalytes are extracted (solubilized) into an acid solution.3.1.6 non-spiked samplea portio
10、n of a homogenizedsample that is targeted for addition of analyte but that is notfortified (spiked) with lead before sample preparation.Analysisresults for this sample are used to correct for background levelsin soil that are used for the spiked and spiked duplicatesamples.3.1.7 reagent blanka diges
11、tate that reflects the maximumtreatment given any one sample within a batch of samples,except that it has no sample initially placed into the digestionvessel. (The same reagents and processing conditions whichare applied to field samples within a batch are also applied tothe reagent blank.) Discussi
12、on: Analysis results from reagentblanks provide information on the level of potential contami-nation experienced by samples processed within the batch.3.1.8 certified reference materialreference material ac-companied by a certificate, one or more of whose propertyvalues are certified by a procedure
13、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 confidence (ISOGuide 30).3.1.9 spiked samplea portion of a single homogenizedsample to which the same known
14、 amount of analyte is added(spiked) before sample digestion. Discussion: Analysis resultsfor these samples are used to provide information on accuracyand precision of the overall analysis process.1This practice is under the jurisdiction of ASTM Committee E06 on Perfor-mance of Buildings and is the d
15、irect responsibility of Subcommittee E06.23 on LeadPaint Abatement.Current edition approved March 10, 2001. Published April 2001. Originallypublished as E 1726 95. Previous edition E 1726 95.2Annual Book of ASTM Standards, Vol 11.01.3Available from Superintendent of Documents, U.S. Government Printi
16、ngOffice, Washington, DC 20402.4Available from ANSI, 11 W 42ndSt., 13thFloor, New York, NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Practice4.1 A representative soil sample is dried and homogenized,and then
17、 digested (in a batch mode with other samples) on a hotplate using nitric acid and hydrogen peroxide. 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 de
18、terminethe potential lead hazard. Hence, effective and efficient meth-ods are required for the preparation 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 ass
19、ociated with lead abatement in andaround buildings and related structures. The practice is alsosuitable 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
20、collected for hazard assessment purposes.5.4 This practice is not capable of determining lead boundwithin 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 t
21、he sample and are independent of potential differ-ences in soil moisture levels among different sampling 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 mainta
22、ining a temperature of100 to 120C.6.1.3 Electric Hot Plate, capable of maintaining a tempera-ture of 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, pl
23、acea2to2.5cm(0.75 to 1 in.) thickaluminum plate on the burner head.6.1.4 Grinding ApparatusMortar and 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, t
24、he following sizes should be readily available:15 mL adjustable, 1000, 500, 250, and 100 L.6.1.6 Sieves, 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 wi
25、th epoxy resin prior to use to protectsamples from potential lead contamination originating in thesolder. 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 t
26、he soilsamples from contact with lead solder common to brass sieves.6.1.7 Thermometers, red alcohol, 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 Grif
27、fin beakers.6.2.2 Plastic Gloves, powderless.6.2.3 Air-Tight Sample Containers1 L (1 qt) or 4 L (1 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 fortificati
28、on of spiked samples.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in this practice. Unless otherwise indicated, all reagentsshall conform to the specifications for the Committee onAnalytical Reagents of the American Chemical Society, wheresuch specifications are available.5O
29、ther grades shall not beused unless it is first ascertained that the reagent is ofsufficiently high 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 %
30、 (w/w), suitable for atomicspectrometry analysis such as spectroscopic grade.7.4 Acetone, reagent, spectroscopic grade.7.5 WaterUnless otherwise indicated, references to watershall mean reagent water as defined by Type I of SpecificationD 1193. (ASTM Type I Water: minimum resistance of 16.7megohmcm,
31、 or equivalent.)7.6 Calibration Stock Solution, 100 g/mL of lead (Pb) indilute nitric acid.8. Sample Preparation Procedure8.1 Sample Pre-Treatment:8.1.1 Treat each sample in a processing batch equally.8.1.2 If possible before removal, break up the soil samplewithin the original containers containing
32、 the samples (see Note3).NOTE 3This will 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 b
33、e visibleafter exposure to the drying oven.8.1.4 Transfer the entire soil sample to the labeled Griffinbeaker. Cover with a watch glass (tip to one side to permit5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of
34、reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.E1726012moisture removal), and place in a drying oven
35、for a minimumof6hatatemperature of 110 6 10C (see Note 4).NOTE 4If the received soil sample is excessively large, then anyattempts to 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 follow
36、ed by re-combining after drying. Samples thatcake or plug the sieve require additional drying. Soil samples should notcake or exhibit 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
37、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 (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
38、tapping or using forced air or other drymethod to prevent cross-contamination. Perform this step in alocation well removed from other 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 c
39、ontain any large objects orroot material, it is not necessary to perform this step with the 4.7 mmsieve.NOTE 6In order to minimize small 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 siev
40、e (U.S. Standard No. 10) to removecoarse material (see Note 6). Discard material retained on thesieve. Clean the sieve between samples 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
41、 area where soil dust will notcontaminate the laboratory operations, such as in front of afume hood.8.1.8 Grind the sample using a porcelain mortar and pestleor other appropriate homogenization apparatus such as ashatter-box or mixer mill. Clean the grinding apparatus be-tween samples to prevent cro
42、ss-contamination betweensamples by rinsing with water and drying. When any materialis retained from 8.1.9, delay cleaning until this 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 sinc
43、e 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 sieve(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 (
44、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 for 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 m
45、aterial back onthe clean U.S. Standard No. 35 (500 m sieve) (see Note 6).Using a stainless steel spoon, help move material around untilno more sample will pass through the sieve, adding the passedmaterial to the previous sample material that passed throughthe sieve. Discard any retained material. Cl
46、ean the sievebetween samples by tapping or using forced air or other drymethod to prevent cross-contamination. Perform this step in 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 eachso
47、il sample and associated QC samples.8.1.12 Transfer sieved portion to a labeled Griffin beakerand place in a drying oven overnight or 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 thi
48、s 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 conta
49、iner repeatedly for about1 min. Determine the mass of each dried homogenized sampleto the nearest 0.001 g and transfer a 1.0 6 0.10 g portion of thesample to a labeled Griffin beaker. Record the mass of eachsample. For sample portions targeted for spiking, add theappropriate volume of a lead standard stock to the beaker (seeNote 10). In the absence of other information, add 500 g oflead to each beaker containing sample portions targeted forspikes and spike duplicates (5 mL of 100 g/mL of Pb stocksolution).NOTE 10The appropriate volume will be de
