1、Designation: D4309 02 (Reapproved 2007)D4309 12Standard Practice forSample Digestion Using Closed Vessel Microwave HeatingTechnique for the Determination of Total Metals in Water1This standard is issued under the fixed designation D4309; the number immediately following the designation indicates the
2、 year oforiginal adoption or, in the case 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. Scope Scope*1.1 This practice covers the general considerati
3、ons for quantitative sample digestion for total metals in water using closed vesselmicrowave heating technique. This practice is applicable to surface, saline, domestic, and industrial wastewater.1.2 Because of the differences among various makes and models of satisfactory instruments, no detailed o
4、perating instructionscan be provided. Instead, the analyst should follow the instructions provided by the manufacturer of the particular instrument.1.3 This practice can be used with the following ASTM standards, providing the user determines precision and bias based onthis digestion practice: Test
5、MethodsMethod D857, Test Methods D858, Test Methods D1068, Specification D1192, Test MethodsD1687, Test Methods D1688, Test Methods D1691, Test Methods D1886, Test Method D1976, Practices D3370, Test MethodsD3557, Test Methods D3559, Practice D3919, Test MethodsMethod D4190, Practice D4453, and Prac
6、tice D4691, and Test MethodD5673.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the use
7、r of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazard statements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D857 Test Method for Aluminum in WaterD858 Test Methods for Manganes
8、e in WaterD1068 Test Methods for Iron in WaterD1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steam in Closed Conduits (Withdrawn 2003)3D1193 Specification for Reagent WaterD1687 Test Methods for Chromium in WaterD1688 Test Methods for Copper in WaterD1691 Test Me
9、thods for Zinc in WaterD1886 Test Methods for Nickel in WaterD1976 Test Method for Elements in Water by Inductively-Coupled Argon Plasma Atomic Emission SpectroscopyD3370 Practices for Sampling Water from Closed ConduitsD3557 Test Methods for Cadmium in WaterD3559 Test Methods for Lead in WaterD3856
10、 Guide for Management Systems in Laboratories Engaged in Analysis of WaterD3919 Practice for Measuring Trace Elements in Water by Graphite Furnace Atomic Absorption SpectrophotometryD4190 Test Method for Elements in Water by Direct-Current Plasma Atomic Emission SpectroscopyD4453 Practice for Handli
11、ng of High Purity Water SamplesD4691 Practice for Measuring Elements in Water by Flame Atomic Absorption Spectrophotometry1 This practice is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents in Water.Current editio
12、n approved June 15, 2007March 1, 2012. Published June 2007March 2012. Originally approved in 1991. Last previous edition approved in 20022007 asD4309 02.D4309 02 (2007). DOI: 10.1520/D4309-02R07.10.1520/D4309-12.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Cust
13、omer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to th
14、e previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary
15、of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D5673 Test Method for Elements in Water by Inductively Coupled PlasmaMass Spectrometry2.2 U.S. Code of Federal Regulations:3CFR 1.03
16、0.10 Code of Federal Regulations, Volume 212.3 Federal Communications Commission Standard:3Code of Federal Regulations, Volume 47, FCC Rule Part 182.4 U.S. EPA Method:4U.S. EPAMethod: Methods for ChemicalAnalysis of Water and WasteMarch 1979, “Total Metals Digestion Procedure” 4.1.3,page Metals 6U.S
17、. EPA Method: SW 846 Method 3015 Microwave Assisted Acid Digestion of Aqueous Samples and Extracts3. Terminology3.1 DefinitionsFor definitions of terms used in this practice, refer to Terminology D1129.4. Summary of Practice4.1 A representative aliquot of a homogeneous sample is digested with acid i
18、n a closed microwave transparent vessel, usingmicrowave heating. The digestate or a filtered digestate is then analyzed by direct aspiration or injection by flame atomicabsorption spectrophotometry (FAAS), inductively coupled plasma emission techniques (ICP), direct current plasma emissiontechniques
19、 (DCP), or graphite furnace atomic absorption spectrophotometry (GFAAS), inductively coupled plasma-massspectrometry (ICP-MS), or a combination of methods.5. Significance and Use5.1 The analysis of many types of water for metals using flame atomic absorption spectrophotometry, inductively coupledpla
20、sma emission spectrophotometry, direct current plasma emission spectrophotometry, or graphite furnace atomic absorptionspectrophotometry necessitates the use of a digestion practice in order to ensure the proper statistical recovery of the metals fromthe sample matrix. The use of closed vessel micro
21、wave techniques will speed the complete recovery of metals from the watermatrices and eliminate sample contamination from external sources.6. Interferences6.1 No interferences have been observed using microwave heating.6.2 Precautions should be exercised to avoid those interferences normally associa
22、ted with the particular analytical method formetals determination.6.3 This practice will not totally solubilize solid silicates that are suspended in or settle out of the water sample.7. Apparatus7.1 Laboratory Microwave Heating System, capable of delivering 575 to 1000 W of power. The unit should b
23、e capable of 1 %power adjustment and 1 s time adjustment. The oven cavity should be fluorocarbon-coated or coated with a material that hasequivalent acid resistance and microwave properties and be equipped with exhaust ventilation at 2.8 m 3/min (100 ft 3/min) for acidvapor protection of the unit an
24、d operator.The unit must have a rotating or alternating turntable, capable of holding 1 to 14 digestionvessels, to ensure even sample heating. Safety interlocks, to shut off magnetron power output, must be contained in the oven dooropening mechanism. The unit may contain a temperature control device
25、 capable of controlling vessel temperatures to 200C and/ora pressure control device capable of controlling vessel pressures to a minimum 100 psig.psi (690 kPa).7.1.1 The unit must comply with U.S. Health and Human Services Standards under CFR Part 1030.10, sub parts (C) (1), (C)(2), and (C) (3), for
26、 microwave leakage. The unit should have FCC-type approval for operations under FCC Rule Part 18.7.2 Closed Vessel, capable of holding 100 mL of solution. The vessel must be transparent to microwave energy and capable ofwithstanding internal pressures of 100 psig psi (690 kPa) and temperatures of 20
27、0C. The vessel must contain a safety pressurerelief valve, rupture disc, pressure venting system or be connected to an external safety relief valve that will prevent possible vesselrupture or ejection of the vessel cap.7.3 Apparatus, to seal the vessel system to the manufacturers specified requireme
28、nt.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall be used in this practice. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications for the Committee onAnalytical Reagents of theAmerican Chemical Society, where3 Available from Office of the Fed
29、eral Register, National Archives Records Administration, U.S. Government Printing Office Superintendent of Documents, U.S.Government Printing Office, Washington, DC 20401.732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.4 Available from National Technical Inform
30、ation Service (NTIS), 5285 Port Royal Rd., Springfield, VA 22161,5301 Shawnee Rd., Alexandria, VA 22312,http:/www.ntis.gov.D4309 122such specifications are available. 5 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without
31、 lessening the accuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water conforming toSpecification D1193, Type I. Other reagent water types may be used provided it is first ascertained that the water is of sufficiently
32、high purity to permit its use without adversely affecting the bias and precision of the method. Type II water was used for the datashown in Appendix X1.8.3 Hydrochloric Acid (sp gr 1.19) (HCl).8.4 Nitric Acid (sp gr 1.42) (HNO3).8.5 Nitric Acid (1 + 1) Add 1 volume of HNO3 (sp gr 1.42) to 1 volume o
33、f water.9. Hazards9.1 The microwave unit should be operated in accordance with the manufacturers recommended operating and safetyprecautions. CautionIt is not recommended to place a microwave unit in a fume hood, where it is surrounded by acid fumes,which can cause corrosion of the equipment.Acid fu
34、mes generated inside the oven cavity should be air swept away from the ovencavity to a hood.9.2 PrecautionThe closed vessel should be operated in accordance with the manufacturers recommended operating andsafety instructions.10. Procedure10.1 Power Temperature Controlprocedure for 7 to 12 vessel dig
35、estions:NOTE 1For fewer than seven samples, see 10.2.10.1.1 Perform an instrument power check as outlined in Annex A1.10.1.2 Refer to ASTM test methods for sampling and analysis (such as Guide D3856) to determine any sample preservationrequirements.10.1.3 Transfer 50.0 mL of a representative aliquot
36、 of the well-mixed sample into a clean vessel (see Note 2). If the sample isto be analyzed by ICP, DCP, or FAAS, add 3 mLof HNO3 (sp gr 1.42) and 2 mLof HCl (sp gr 1.19). If the sample is to be analyzedby GFAAS, add 5 mL of HNO3 (sp gr 1.42) (see Note 3). Install a safety pressure relief valve and c
37、ap on the vessel and seal tothe manufacturers recommended torque. Weigh the vessel, record the weight, and place in the microwave instrument turntable.Attach a vent tube, if required, by the manufacturers operating instructions.NOTE 2Follow the manufacturers suggested vessel cleaning instructions to
38、 avoid possible sample contamination.NOTE 3Final acid concentration of this procedure is 9 %. This may shorten graphite tube lifetime, which may cause deterioration of analyte recovery.The analyst may choose to dilute the digested solution to a lower acid percentage to increase graphite tube life.10
39、.1.4 Repeat 10.1.3 until the turntable contains 12 vessels. A reagent blank should be digested and analyzed along with thesamples. If less than 12 samples are to be digested, fill the remaining vessels with 50 mL of water and add an equal amount ofacid as added to the sample. It is critical to the p
40、rocedure that the total volume of solutions equals 660 mL during digestion, andthat each vessel contains an equal volume of acid. This is necessary to ensure uniform heating of all vessel solutions.NOTE 4It is not necessary to weigh the blank vessels containing 50 mL of reagent water.10.1.5 Turn the
41、 microwave instrument exhaust on to the maximum fan speed. Activate the turntable so that it is rotating oralternating 360.10.1.6 For instruments delivering a measured power of 575 to 635 W, program the instrument time for 50 min and the powerto 100 %. For instruments with a measured power of 635 to
42、 700 W, program the instrument time for 30 min and the power for100 %. These heating parameters will allow the samples to reach a maximum temperature of 164 6 4C (refer to Fig. 1).Instruments delivering greater than 700 W must be operated at reduced powers such that the sample heating rates match th
43、e heatingrates in Fig. 1. Depress the start key and allow the sample mixtures to heat for the programmed time.10.1.7 At the end of the digestion period, remove the vessels from the microwave and allow the sample solutions to cool to roomtemperature. Shake the vessels to mix the sample solutions and
44、vent to atmosphere any gas pressure that may be present in thevessels.NOTE 5Warning:Warning Shake Shake the vessel with caution to prevent any rapid out-gassing of vapor or liquid causing acid burns of theexposed skin of the operator.5 Reagent Chemicals, American Chemical Society Specifications , Am
45、erican Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc.
46、(USPC), Rockville, MD.D4309 12310.1.8 Detach the vent tubing and remove the vessel assembly from the turntable. Weigh the cooled vessel system. If there isa weight loss greater than 0.5 g, open the vessel and add an amount of reagent water equal to the weight loss. Liquid loss of lessthan 10 % has n
47、ot been found to result in any analyte loss (see Note 6). Recap the vessel and then shake the vessel to mix thesample solution.NOTE 6Samples containing large amounts of organics may experience excessive loss of liquid (greater than 10 %); therefore, a study may be requiredto determine if any analyte
48、 loss occurred.10.1.9 Open the vessels and filter the samples, if required, to remove silicates and other insoluble materials. Do not rinse ordilute the digested sample. Final sample volume is 55 mL (see Note 3).NOTE 7In place of filtering, the sample after mixing may be centrifuged or allowed to se
49、ttle by gravity overnight to remove insoluble material.10.1.10 Analyze the sample by ICP, DCP, FAAS or FAAS, GFAAS, or ICP-MS, or a combination of methods, as required.10.2 Power Temperature Controlprocedure for 1 to 6 vessel digestions:10.2.1 Perform an instrument power check as outlined in Annex A2.10.2.2 Refer to individual ASTM test methods for sampling and analysis to determine any sample preservation requirements.10.2.3 Transfer 50.0 mL of a representative aliquot of the well-mixed sample into a clean vessel (see Note 2). If the sample isto
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