ASTM D4309-2018 Standard Practice for Sample Digestion Using Closed Vessel Microwave Heating Technique for the Determination of Total Metals in Water.pdf

1、Designation: D4309 12D4309 18Standard 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 year oforiginal a

2、doption 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*1.1 This practice covers the general considerations for quantitative sam

3、ple 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 operating instructionscan

4、 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 Method D857, Test Method

5、s D858, Test Methods D1068, Test Methods D1687, Test Methods D1688,Test Methods D1691, Test Methods D1886, Test Method D1976, Practices D3370, Test Methods D3557, Test Methods D3559,Practice D3919, Test Method D4190, Practice D4453, Practice D4691, and Test Method D5673.1.4 The values stated in SI u

6、nits are to be regarded as standard. No other units of measurement are included in this The valuesgiven in parentheses are mathematical conversion to inch-pound units that are provided for information only and are not consideredstandard.1.5 This standard does not purport to address all of the safety

7、 concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use. For specific hazard statements, see Section 9.1.6

8、This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade

9、(TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D857 Test Method for Aluminum in WaterD858 Test Methods for Manganese in WaterD1068 Test Methods for Iron in WaterD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD1687 Test Methods for Chromium in WaterD1688 Test Meth

10、ods for Copper in WaterD1691 Test Methods 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

11、 Test Methods for Lead in WaterD3856 Guide for Management Systems in Laboratories Engaged in Analysis of WaterD3919 Practice for Measuring Trace Elements in Water by Graphite Furnace Atomic Absorption Spectrophotometry1 This practice is under the jurisdiction of ASTM Committee D19 on Water and is th

12、e direct responsibility of Subcommittee D19.05 on Inorganic Constituents in Water.Current edition approved March 1, 2012Feb. 1, 2018. Published March 2012May 2018. Originally approved in 1991. Last previous edition approved in 20072012 asD4309 02 (2007).D4309 12. DOI: 10.1520/D4309-12.10.1520/D4309-

13、18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer 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

14、 to provide the user of an ASTM standard an indication of what changes have been made to the 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 versio

15、nof the standard as published by ASTM is to be considered the official document.*A Summary 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 States1D4190 Test Method for Elements in Water b

16、y Direct-Current Plasma Atomic Emission SpectroscopyD4453 Practice for Handling of High Purity Water SamplesD4691 Practice for Measuring Elements in Water by Flame Atomic Absorption SpectrophotometryD5673 Test Method for Elements in Water by Inductively Coupled PlasmaMass Spectrometry2.2 U.S. Code o

17、f Federal Regulations:3CFR 1.030.10 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 ofWater andWasteMarch 1979, “Total Metals Digestion Proc

18、edure” 4.1.3,page Metals 6U.S. EPA Method: SW 846 Method 3015 Microwave Assisted Acid Digestion of Aqueous Samples and Extracts3. Terminology3.1 DefinitionsDefinitions: For definitions of terms used in this practice, refer to Terminology D1129.3.1.1 For definitions of terms used in this standard, re

19、fer to Terminology D1129.4. Summary of Practice4.1 A representative aliquot of a homogeneous sample is digested with acid in a closed microwave transparent vessel, usingmicrowave heating. The digestate or a filtered digestate is then analyzed by direct aspiration or injection by flame atomicabsorpti

20、on spectrophotometry (FAAS), inductively coupled plasma emission techniques (ICP), direct current plasma emissiontechniques (DCP), graphite furnace atomic absorption spectrophotometry (GFAAS), inductively coupled plasma-mass spectrom-etry (ICP-MS), or a combination of methods.5. Significance and Use

21、5.1 The analysis of many types of water for metals using flame atomic absorption spectrophotometry, inductively coupledplasma emission spectrophotometry, direct current plasma emission spectrophotometry, or graphite furnace atomic absorptionspectrophotometry necessitates the use of a digestion pract

22、ice in order to ensure the proper statistical recovery of the metals fromthe sample matrix. The use of closed vessel microwave techniques will speed the complete recovery of metals from the watermatrices and eliminate sample contamination from external sources.6. Interferences6.1 No interferences ha

23、ve been observed using microwave heating.6.2 Precautions should be exercised to avoid those interferences normally associated 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 s

24、ample.7. Apparatus7.1 Laboratory Microwave Heating System, capable of delivering 575 to 1000 W of power. The unit should be 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

25、 properties and be equipped with exhaust ventilation at 2.8 m 3/min (100 ft 3/min) for acidvapor protection of the unit and 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 magn

26、etron power output, must be contained in the oven dooropening mechanism. The unit may contain a temperature control device capable of controlling vessel temperatures to 200C and/ora pressure control device capable of controlling vessel pressures to a minimum 100 psi (690 kPa).690 kPa (100 psi).7.1.1

27、 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 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

28、 must be transparent to microwave energy and capable ofwithstanding internal pressures of 100 psi (690 kPa)690 kPa (100 psi) and temperatures of 200C. The vessel must contain a safetypressure relief valve, rupture disc, pressure venting system or be connected to an external safety relief valve that

29、will preventpossible vessel rupture or ejection of the vessel cap.7.3 Apparatus, to seal the vessel system to the manufacturers specified requirement.3 Available from U.S. Government Printing Office, Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401,20401-0001

30、,http:/www.access.gpo.gov.4 Available from National Technical Information Service (NTIS), 5301 Shawnee Rd., Alexandria, VA 22312, http:/www.ntis.gov.D4309 1828. Reagents8.1 Purity of ReagentsReagent grade chemicals shall be used in this practice. Unless otherwise indicated, it is intended thatall re

31、agents shall conform to the specifications for the Committee onAnalytical Reagents of theAmerican Chemical Society, wheresuch 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 lessening

32、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 sufficientlyhigh purity

33、 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 of water.9. H

34、azards9.1 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 fumes generate

35、d 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 digestions:NOTE

36、 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 of the well

37、-mixed sample into a clean vessel (see Note 2). If the sample isto be analyzed by ICP, ICP-MS, ICP-AES, DCP, or FAAS, add 3 mL of HNO3 (sp gr 1.42) and 2 mL of HCl (sp gr 1.19). If thesample is to be analyzed by GFAAS, add 5 mL of HNO3 (sp gr 1.42) (see Note 3). Install a safety pressure relief valv

38、e and capon the vessel and seal to the manufacturers recommended torque. Weigh the vessel, record the weight, and place in the microwaveinstrument turntable. Attach a vent tube, if required, by the manufacturers operating instructions.NOTE 2Follow the manufacturers suggested vessel cleaning instruct

39、ions to 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

40、life.10.1.4 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 t

41、o the procedure 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 T

42、urn the 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

43、 635 to 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 m

44、atch the 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 solutio

45、ns and vent to atmosphere any gas pressure that may be present in thevessels. (WarningShake 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, , American Che

46、mical 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. (USPC), Ro

47、ckville, MD.D4309 183NOTE 5WarningShake the vessel with caution to prevent any rapid out-gassing of vapor or liquid causing acid burns of the exposed skin of theoperator.10.1.8 Detach the vent tubing and remove the vessel assembly from the turntable. Weigh the cooled vessel system. If there isa weig

48、ht 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 not been found to result in any analyte loss (see Note 65). Recap the vessel and then shake the vessel to mix thesample solution.NOTE 5Samples containing large am

49、ounts of organics may experience excessive loss of liquid (greater than 10 %); therefore, a study may be requiredto determine if any analyte 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 6In place of filtering, the sample after mixing may be centrifuged or allowed to settle by gravity overnight to remove insoluble material.10.1.10 Analyze the sample by ICP, ICP-MS, ICP-AES, DCP, F