1、Designation: E 1645 01 (Reapproved 2007)Standard Practice forPreparation of Dried Paint Samples by Hotplate orMicrowave Digestion for Subsequent Lead Analysis1This standard is issued under the fixed designation E 1645; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, the 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 the sample preparation proceduresfor paint sampl
3、es that are collected during the assessment,management or control of lead hazards.1.2 This practice describes the digestion procedures using ahot plate or microwave oven or apparatus for paint samples thatare to be analyzed for lead content.1.3 This practice covers the general considerations forquan
4、titative sample extraction for total recoverable lead indried paint samples (either bulk paint or paint powder) usinghot plate or microwave heating techniques, or both.1.4 The values stated in SI units are to be regarded as thestandard.1.5 This practice contains notes that are explanatory and notpar
5、t of the mandatory requirements of the standard.1.6 This practice is based on two NIOSH Methods, 7082and 7105, and on an EPA standard operating procedure for leadin paint.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility
6、 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. For specificprecautionary statements, see 6.2.4.4 and 7.2.1.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 11
7、93 Specification for Reagent WaterE 1605 Terminology Relating to Lead in BuildingsE 1729 Practice for Field Collection of Dried Paint Samplesfor Subsequent Lead Determination2.2 Other Documents:Environmental Protection Agency, Standard Operating Pro-cedures for Lead in Paint by Hotplate- or Microwav
8、e-based Acid Digestions and Atomic Absorption or Induc-tively Coupled Plasma Emission Spectrometry; U.S. EPA,Research Triangle Park, NC (1991). (NTIS No.PB92114172)3NIOSH Manual of Analytical Methods, P.M. Eller and M.E.Cassinelli, Eds., 4th ed., Methods 7082 and 7105; Na-tional Institute for Occupa
9、tional Safety (800)35NIOSH.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.except that it has no sample placed initially into the digestionvessel. (The same reagents and processing conditions that areapplied to field samples within a
10、 batch are also applied to thereagent blank.)3.1.7.1 DiscussionAnalysis results from this sample pro-vide information on the level of potential contaminationresulting from only laboratory sources that are experienced bysamples processed within the batch.3.1.8 reference material (certified reference
11、material)(CRM)a material of known composition where the lead levelis certified by the manufacturer.3.1.9 sample seta group of samples (one or more).3.1.10 spiked sample or spiked duplicate sample a blankmedium that contains no purposely added analyte to which aknown amount of analyte is added before
12、 preparation.3.1.10.1 DiscussionAnalysis results for these samples areused to provide information on the precision and accuracy ofthe overall process.4. Summary of Practice4.1 Lead in dried paint samples (chips, powder, etc.) issolubilized (extracted) by digestion with nitric acid and hydro-gen pero
13、xide facilitated by heat, or by a mixture of nitric acidand hydrochloric acid facilitated by microwave energy. (It isassumed that the paint samples were collected in accordancewith Practice E 1729; however, this practice can be used forany collected paint sample.) The lead content of the digestedsam
14、ple is then in a form ready for measurement.5. Significance and Use5.1 Paint in buildings and related structures needs to bemonitored for lead content in order to determine the potentiallead hazard. Hence, effective and efficient methods are requiredfor the preparation of paint samples that may cont
15、ain lead.5.2 This practice may be used for the digestion of paintsamples that are collected during various lead-hazard controland risk assessment activities associated with lead abatement inand around buildings and related structures. This practice isalso suitable for the digestion of paint samples
16、collected fromlocations such as commercial buildings.5.3 This practice may be used to prepare samples that havebeen obtained in order to ensure compliance with laws thatgovern lead content in paints.5.4 This practice may be used to prepare samples that havebeen collected for risk assessment purposes
17、.5.5 This practice is intended for use with paint samples thatare prepared for subsequent analysis by laboratory-basedquantitative analytical methods.6. Apparatus6.1 Heating Equipment:6.1.1 Electric Hot Platesuitable for operation at surfacetemperatures up to at least 140C. A temperature of at least
18、100C, as measured by a thermometer placed inside a boro-silicate glass container (on the hot plate) filled with digestionsolution, should be attainable. (See Note 1.)NOTE 1Provided that the hot plate is capable of handling the extraheating required, use of a 12 to 25-mm (approximately 0.5 to 1-in.)
19、thickaluminum plate placed on the burner head can help reduce the presence ofhot spots common to electric hot plates.6.1.2 Microwave Extraction ApparatusCaution: Ensure that manufacturers safety recommenda-tions are followed.NOTE 2The procedure described is for microwave digestion systemswith a temp
20、erature control system. Microwave digestion systems that areequipped only with a pressure control system or lower pressure vessels, orboth, may be used, provided that a prior assessment of the dissolutionefficiency is carried out.6.1.2.1 Microwave Digestion Systemdesigned for closedvessel digestion,
21、 with power output regulation, fitted with atemperature control system capable of sensing the temperatureto within 62C, and automatically adjusting the microwavepower output within 2 s. The microwave cavity shall beresistant to chemical attack, and equipped with exhaust venti-lation for acid vapor p
22、rotection of the unit and operator. Allelectronics shall be protected against corrosion to ensure safeoperation. Safety interlocks, to shut off magnetron poweroutput, shall be contained within the oven door openingmechanism.Caution: Domestic (kitchen) microwave ovens shall not beused, since there ar
23、e very significant hazards associated withtheir use for the procedure described in this standard. Forexample, acid vapors released into the cavity can corrodesafety devices that prevent the magnetron from shutting offwhen the door is opened, potentially exposing the operator tomicrowave energy.Also,
24、 the fumes generated can be extremelyhazardous.NOTE 3Apressure control system is also very useful, since it providesa safeguard against the possibility of sample loss due to excessive pressurebuildup and partial venting of the sample vessels.6.1.2.2 Lined Sample Vesselsclosed, designed for carry-ing
25、 out microwave digestions, capable of withstanding atemperature of at least 180C and with an internal volume of atleast 50 mL. The vessels must be transparent to microwaveenergy, and vessel liners shall be chemically inert. The vesselsmust be capable of withstanding high internal pressures (up toat
26、least 3000 kPa) and temperatures (up to at least 180C).Vessels shall also be equipped with a safety relief valve or discthat will prevent vessel rupture or ejection of the vessel cap.Such vessels consist of an inner liner and cover made of amicrowave transparent and chemically resistant material (us
27、u-ally a fluorocarbon polymer such as tetra-fluoromethoxil poly-mer (TFM), which contains and isolates the sample solutionfrom a high strength, outer pressure structure. Other types ofsample vessels designed to operate at equivalent or highertemperatures or pressures, or both, may be used.Caution: F
28、or closed vessel designs, the material from whichthe outer vessels are made is usually not as chemically inert asthe liner material. Since the outer vessels provide the strengthrequired to withstand the high pressures within the inner liners,they must be inspected regularly to check for any chemical
29、 orphysical degradation.6.2 Reagents, Glassware and Supplies:6.2.1 Apparatus-Hot Plate Digestion:6.2.1.1 Borosilicate glass beakers, 125-mL or 50-mL withwatchglass covers,E 1645 01 (2007)26.2.1.2 Class A borosilicate volumetric flasks, 100mL and200mL,6.2.1.3 Class A borosilicate volumetric pipets, v
30、olume asneeded,6.2.1.4 Linear polyethylene bottles with caps, 100mL,6.2.1.5 Analytical balance, accurate to 60.1 mg,6.2.1.6 Glass funnels, and6.2.1.7 Filter paper,6.2.1.8 Weighing Paper or Weighing Boat.6.2.2 Apparatus-Microwave Digestion:6.2.2.1 Centrifuge, with 30 mL polysulfone centrifuge tubesan
31、d polypropylene screw closure,6.2.2.2 Class A volumetric and graduated pipets,6.2.2.3 Mechanical shaker, and6.2.2.4 Analytical balance, accurate to 60.1 mg.6.2.3 Reagents-Hot Plate Digestion:6.2.3.1 Concentrated nitric acid, ACS reagent grade orspectrographic grade 16.0 M HNO3,6.2.3.2 Nitric acid, 1
32、0 % (w/v): Add 100 mL concentratedHNO3to 500 mL ASTM Type I water (see SpecificationD 1193). Dilute to 1 L with ASTM Type I water,6.2.3.3 Hydrogen peroxide,30%H2O2(w/w); ACS reagentgrade, and6.2.3.4 ASTM Type I water (see Specification D 1193).6.2.4 Reagents-Microwave Digestion:6.2.4.1 Concentrated
33、nitric acid, ACS reagent grade orspectrographic grade 16.0 M HNO3,6.2.4.2 Concentrated hydrochloric acid, ACS reagent grade12.3 M HCl,6.2.4.3 ASTM Type I water (see Specification D 1193), and6.2.4.4 Extraction SolutionIn a 1-L volumetric flask,combine the following in order and mix well: 500 mL ASTM
34、Type I water, 60 mL concentrated HNO3and 180 mL concen-trated HCl. Cool to room temperature and dilute to 1 L withASTM Type I water. Caution: Nitric and hydrochloric acidfumes are toxic. Prepare in a well-ventilated fume hood.7. Sample Treatment7.1 Sample Preparation:7.1.1 Sample Mass and AreaAfter
35、analysis, report thefinal results in area concentration (mg Pb/cm2) or massconcentration (ppm Pb, percent Pb by mass, or alternativeunits). If area concentration is desired, sample areas must beprovided (by the person submitting the samples) for each paintsample (chip, powder, etc.). The total mass
36、of area concentra-tion samples must be determined. Samples may be subsampled(after grinding and homogenization), depending on the samplemass.7.1.2 Area SamplesFor each field sample, homogenize thedried paint sample (inside the original sample container, ifpossible) as described in the following:7.1.
37、2.1 Don a new clean pair of vinyl gloves to performsample handling.7.1.2.2 Remove any large amounts of substrate present inthe sample. Exercise care when removing substrate to avoidany losses of paint. If required, use a clean safety razor bladeor equivalent tool to aid in substrate removal.7.1.2.3
38、Determination of Total Collected Sample MassAccurate determination of the collected sample mass is re-quired to report lead analysis results in terms of area concen-tration (mass per unit area of paint sample). A completetransfer of the sample is required to whatever preweighedcontainer is used to h
39、old the sample during mass determination(for example, weighing boat or weighing paper). Total massshall be made to the nearest 0.1 mg.The following precautions shall be observed during deter-mination of total mass:(1) Total sample mass can be determined either before orafter sample homogenization. D
40、etermination of total samplemass is generally advisable prior to homogenization whensamples consist of large intact chips that can be easilytransferred without incurring losses. Determination of totalsample mass is generally advisable after homogenization whensamples can be homogenized in the origin
41、al sample collectioncontainer and the samples are not large intact chips.NOTE 4In this case, the sample container should be weighed afterhomogenization.(2)Any visible traces of paint left in the original container orcontainer used for homogenization (if different from originalcontainer) may result i
42、n bias of the final lead analysis results.Therefore, such traces shall be minimized.Any visible materialthat cannot be transferred shall be documented in samplepreparation records.(3) For sample transfers following homogenization, mostlosses caused by the presence of fine powder remaining in theorig
43、inal container or container used for homogenization (ifdifferent from original container) will not result in any signifi-cant bias (particularly with respect to the large samplingvariability that normally accompanies the field collectionpractice.)(4) For sample transfers prior to homogenization (tha
44、t is,when homogenization cannot be performed in the originalcontainer used in sample collection), any losses caused by finepowder remaining in the original container may result in asignificant bias. Therefore, sample transfers conducted prior tosample homogenization shall be performed with extra att
45、entionto avoiding visible traces of paint left in the original container.NOTE 5If sample mass is determined after homogenization in thecollection container, the container should be weighed (clean) either beforesampling, or after sample homogenization, reweighing (immediatelyfollowing sample transfer
46、), and recleaning.7.1.2.4 Homogenization of SamplesSamples shall be ho-mogenized as finely as possible, regardless of whether areaconcentration or mass concentration results are desired. Thehomogenization of the sample serves two purposes: (a) toensure the the subsamples will be representative of th
47、e wholecollected sample; and (b) to maximize the extraction anddigestion efficiency of the sample.Any sample homogenizationtechnique that meets the following criteria may be used:(1) Samples shall be ground, crushed or broken into a finepowder or small granules consisting of particles no larger than
48、that visually represented by the size of a poppy seed or smallgrain of sand (no larger than 0.5 mm in diameter).(2) Samples shall not be contaminated from any otherpreviously processed sample. This means that the samplehomogenization technique is carried out such that carefulE 1645 01 (2007)3cleanin
49、g between samples is performed on the equipment usedto process multiple samples.NOTE 6Sample homogenization techniques that employ cold tem-peratures, such as dry ice-assisted grinding or liquid nitrogen shatter boxmills, can be extremely effective in homogenizing paint samples, and arerecommended, but not required. Such homogenization techniques can beused in lieu of or in addition to the use of a mortar and pestle or othergrinding technique.7.1.2.5 Hot Plate DigestionsDetermine the mass, to thenearest 0.1 mg, of a 0.25 to 0.50 g subsample of thehomogeni
