ASTM D5513-22

Standard Practice for Microwave Digestion of Industrial Furnace Feed Streams and Waste for Trace Element Analysis

SIGNIFICANCE AND USE
5.1 The U.S. Environmental Protection Agency Regulations, 40 CFR 266, require that boilers, cement kilns, and other industrial furnaces utilizing waste-derived fuel adhere to specific guidelines in assessing potential metals emissions. A common approach for estimating potential emissions is performing total metals analysis on all feed stream materials. This practice describes a multi-stage microwave-assisted digestion procedure that solubilizes trace elements for spectroscopic analyses.
SCOPE
1.1 This practice describes the multi-stage microwave digestion of typical industrial furnace feed stream materials using nitric, hydrofluoric, hydrochloric, and boric acids for the subsequent determination of trace metals.  
1.2 This practice has been used successfully on samples of coal, coke, cement raw feed materials, and waste-derived fuels composed primarily of waste paint-related material in preparation for measuring the following trace elements: Ag, As, Ba, Be, Cd, Cr, Hg, Pb, Sb, and Tl. This practice may be applicable to elements not listed above.  
1.3 This practice is also effective for other waste materials (for example, fly ash, foundry sand, alum process residue, cement kiln dust, etc.).  
1.4 The values stated in SI units are to be regarded as standard. Other units of measurement in parentheses in this standard are informational.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 8.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2022
• ICS: 25.180.10 - Electric furnaces
• Technical Committee: D34 - Waste Management
• Drafting Committee: D34.01.06 - Analytical Methods

Relations

• Refers: ASTM D5681-23 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Nov-2023
• Refers: ASTM D5681-18 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Nov-2018
• Refers: ASTM D5681-17 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Sep-2017
• Refers: ASTM D5681-16a - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Nov-2016
• Refers: ASTM D5681-16 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Feb-2016
• Refers: ASTM D5681-13 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Feb-2013
• Refers: ASTM D5681-09 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Jul-2009
• Refers: ASTM D5681-08 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Sep-2008
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D5681-98a(2004)e1 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Sep-2004
• Refers: ASTM D5681-98a(2004) - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Sep-2004
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D5681-98ae1 - Standard Terminology for Waste and Waste Management
• Effective Date: 10-Jun-1998
• Refers: ASTM D5681-98a - Standard Terminology for Waste and Waste Management
• Effective Date: 10-Jun-1998

Overview

ASTM D5513-22: Standard Practice for Microwave Digestion of Industrial Furnace Feed Streams and Waste for Trace Element Analysis outlines procedures for preparing feed stream and waste samples for total metals analysis. This standard, developed by ASTM International, is widely applied in industries needing to assess trace element content in materials subjected to high-temperature processing. The practice employs a multi-stage microwave digestion technique utilizing nitric, hydrofluoric, hydrochloric, and boric acids. Its primary goal is to dissolve trace metals within complex matrices, enabling accurate spectroscopic analyses required for regulatory compliance-especially under U.S. Environmental Protection Agency (EPA) regulations, such as 40 CFR 266 for hazardous waste incineration in industrial furnaces.

Key Topics

• Microwave-Assisted Digestion Procedure
  Multi-stage digestion using specific acid sequences to ensure complete solubilization of trace elements in various industrial and waste materials.
• Sample Types
  Applicable to coal, coke, cement raw feed, waste-derived fuels (such as waste paint-related material), fly ash, foundry sand, alum process residue, and cement kiln dust.
• Target Trace Elements
  Method suitable for analysis of Ag, As, Ba, Be, Cd, Cr, Hg, Pb, Sb, and Tl, and may be extended to additional trace metals.
• EPA Metals Emissions Requirements
  Addresses regulatory requirements for analyzing metals in furnace feed streams to minimize potential emissions.
• Lab Safety and Handling
  Provides guidance on safe handling of corrosive acids (nitric, hydrofluoric, hydrochloric) and procedures for managing potentially hazardous materials.
• Quality Assurance
  Recommends inclusion of blanks, certified reference standards, and matrix spikes in digestion batches to ensure analytical quality and reliability.

Applications

• Environmental Compliance in Industrial Operations
  Used by power plants, cement manufacturers, and waste incinerators to demonstrate compliance with EPA hazardous waste and air emission standards.
• Trace Metals Analysis for Process Control
  Enables accurate determination of total metals in raw materials and waste feeds, which is vital for process optimization, emissions tracking, and safety management.
• Spectroscopic Analysis Preparation
  Ensures samples are fully digested and compatible with downstream analytical techniques such as atomic absorption spectroscopy (AAS) and inductively coupled plasma (ICP) spectrometry.
• Research and Development
  Facilitates materials characterization in R&D laboratories focusing on fuels, byproducts, and new feedstocks in high-temperature industrial processes.
• Cross-Industry Waste Management
  Supports facilities in the characterization and safe disposal of industrial wastes, reducing environmental impact and supporting sustainable practices.

Related Standards

• ASTM D1193 - Specification for Reagent Water
  Defines quality requirements for water used in analytical testing.
• ASTM D5681 - Terminology for Waste and Waste Management
  Establishes terminology for consistent communication in waste analysis and management.
• EPA 40 CFR 266 Subpart H
  U.S. regulatory framework for hazardous waste burned in industrial furnaces and boilers.
• International Principles
  Developed in line with the World Trade Organization’s Technical Barriers to Trade (TBT) guidelines for international standardization.

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Keywords: ASTM D5513-22, microwave digestion, industrial furnace, waste analysis, trace elements, metals emissions, EPA compliance, feed stream, coal, coke, cement, waste-derived fuels, fly ash, laboratory analysis, spectroscopic analysis.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5513 − 22
Standard Practice for
Microwave Digestion of Industrial Furnace Feed Streams
and Waste for Trace Element Analysis
This standard is issued under the fixed designation D5513; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice describes the multi-stage microwave di-
D1193Specification for Reagent Water
gestionoftypicalindustrialfurnacefeedstreammaterialsusing
D5681Terminology for Waste and Waste Management
nitric, hydrofluoric, hydrochloric, and boric acids for the
2.2 Other Document:
subsequent determination of trace metals.
40 CFR 266Subpart H, HazardousWaste Burned in Boilers
1.2 This practice has been used successfully on samples of
and Industrial Furnaces, Latest Revision
coal, coke, cement raw feed materials, and waste-derived fuels
3. Terminology
composed primarily of waste paint-related material in prepa-
ration for measuring the following trace elements:Ag,As, Ba,
3.1 For definitions of terms used in this practice, refer to
Be,Cd,Cr,Hg,Pb,Sb,andTl.Thispracticemaybeapplicable
Terminology D5681.
to elements not listed above.
4. Summary of Practice
1.3 This practice is also effective for other waste materials
4.1 A weighed portion of the feed stream material is
(for example, fly ash, foundry sand, alum process residue,
combined with concentrated nitric acid in a
cement kiln dust, etc.).
polytetrafluoroethylene-lined digestion vessel, and heated in a
microwave digestion unit. Following a programmed heating
1.4 The values stated in SI units are to be regarded as
standard. Other units of measurement in parentheses in this cycle, the vessel is vented and specified quantities of hydro-
fluoric and hydrochloric acids are added, and the mixture
standard are informational.
undergoes further microwave heating. Following this heating
1.5 This standard does not purport to address all of the
cycle,thevesselisventedandaspecifiedquantityofboricacid
safety concerns, if any, associated with its use. It is the
solutionisadded,andthemixtureundergoesafinalmicrowave
responsibility of the user of this standard to establish appro-
heating.Followingthisfinalheatingcycle,thevesselisvented,
priate safety, health, and environmental practices and deter-
thecontentsarequantitativelytransferredtoavolumetricflask,
mine the applicability of regulatory limitations prior to use.
and brought to volume. Typically, the only undissolved mate-
Specific hazard statements are given in Section 8.
rial is particulate carbon. If particulate matter is observed,
1.6 This international standard was developed in accor-
filtrationorcentrifugationmaybeneeded.Thedigestedsample
dance with internationally recognized principles on standard-
is ready for analysis.
ization established in the Decision on Principles for the
5. Significance and Use
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
5.1 The U.S. Environmental Protection Agency
Barriers to Trade (TBT) Committee.
Regulations, 40 CFR 266, require that boilers, cement kilns,
and other industrial furnaces utilizing waste-derived fuel ad-
here to specific guidelines in assessing potential metals emis-
sions. A common approach for estimating potential emissions
isperformingtotalmetalsanalysisonallfeedstreammaterials.
1 2
This practice is under the jurisdiction of ASTM Committee D34 on Waste For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Management and is the direct responsibility of Subcommittee D34.01.06 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Analytical Methods. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 1, 2022. Published October 2022. Originally the ASTM website.
approved in 1994. Last previous edition approved in 2015 as D5513–15. DOI: AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700
10.1520/D5513-22. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5513 − 22
This practice describes a multi-stage microwave-assisted di- 8. Hazards
gestion procedure that solubilizes trace elements for spectro-
8.1 It is recommended that all operations involving concen-
scopic analyses.
trated acids be performed in a laboratory fume hood.
6. Apparatus 8.2 Hydrochloric acid is a highly corrosive chemical that is
reactive with metals and most alkaline chemicals. Impervious
6.1 Microwave Digestion Unit—Equipped with an auto-
gloves and chemical goggles are required for handling. See
matic turntable, pressure and/or temperature controller, and
Safety Data Sheet (SDS) for additional information.
closed perfluoroalkoxy (PFA)-lined digestion vessels equipped
with pressure relief/rupture membrane fittings or equivalent 8.3 Hydrofluoric acid is a highly corrosive chemical that is
reactive with metals and water or steam. Additionally, HF
pressure relief device.The unit should comply with applicable
regional, federal, or state standards for microwave leakage. specifically attacks silicate glass, making certain fume hood
enclosures susceptible to damage. Impervious gloves and
The user must follow specific manufacturer’s instructions for
system installation. chemical goggles are required for handling. See SDS for
additional information.
NOTE 1—The digestion unit used in developing this practice was
equipped with a pressure controller, automatic turntable, exhaust fan, and 8.4 Nitricacidisahighlycorrosivechemicalthatisreactive
programming capacity. The unit delivered 1000 W of power at 100%
withmetalsandmostorganicmaterials.Imperviousglovesand
output.The lined digestion vessels consisted of a high-strength polymeric
chemical goggles are required for handling. See SDS for
vessel body and cap, inner PFAliner and rupture membrane housing, and
additional information.
PFA vent stem. These vessels have a maximum operating pressure of
1378.9 kPa (200 psig). There are a number of suitable lab grade
8.5 Some samples undergoing microwave digestion can
microwave systems available to the user that meet these minimum
exhibit a rapid pressure rise within the digestion vessel. The
specifications. The user must follow specific manufacturer’s instructions
potential exists for this type of sample to rupture the rupture
for using digestion vessels.
membrane and liberate corrosive gases. Because of this, the
6.2 Analytical Balance—Capable of weighing to 0.001g
microwave unit must be vented to a fume hood for proper
(1mg).
evacuation of vapors.
6.3 Labware—High-density volumetric polyethylene or
9. Sample
polypropylene flasks/sample containers are recommended for
this practice. The user should be mindful of the quality
9.1 Althoughfeedstreammaterialsaregenerallypulverized
limitations associated with volumetric non-glass labware.
powders or liquids, the homogeneity of some feed stream
materials can be uncertain. The laboratory sample should be
7. Reagents and Materials
thoroughly mixed or homogenized prior to withdrawing a
7.1 Purity of Reagents—Reagent grade chemicals shall be
portionforanalysis.Thispracticeassumesthatnon-liquidfeed
used in all tests. Unless otherwise indicated, it is intended that
streams are pulverized powders at the time of sample prepa-
all reagents conform to the specifications of the Committee on
ration.
Analytical Reagents of theAmerican Chemical Society, where
NOTE 2—If a non-liquid feed stream material is not in the form of a
such specifications are available. Other grades may be used
pulverized powder, it may need to be reduced in particle size to pass
provided it is first ascertained that the reagent is of sufficiently
through a No. 100 sieve.
high purity to permit its use without lessening the accuracy of
10. Calibration and Standardization
the determination.
10.1 Although equipment manufacturers specify general
7.2 Purity of Water—Unless otherwise indicated, references
power output ratings for microwave digestion units, it is
to water shall be understood to mean meeting the numerical
importanttoverifytheactualpoweroutputofaspecificunit.It
requirements of Type II water as defined by Specification
is recommended, and may be required in some applications,
D1193.
that this microwave power check procedure be performed
7.3 Boric Acid Solution (20 g/L)—Dissolve 20 g of boric
monthly.
acid (H BO ) in water and dilute to 1 L. It may be necessary
3 3
10.1.1 Power Check Procedure at 100 % Instrument Power:
to place solution on a combination hot plate/magnetic stirrer
10.1.1.1 Remove from the instrument cavity the turntable,
and with the aid of a stir bar, allow the solution to mix under
drive lug, and all vessels.
gentle heat until boric acid is fully in solution.
10.1.1.2 Adjust the instrument cavity exhaust to minimum
7.4 Hydrochloric Acid, 37%, (sp. gr. 1.200), HCl.
air flow (refer to the manufacturer’s instructions).
10.1.1.3 Program the instrument for 4 min time and 100%
7.5 Hydrofluoric Acid, 48%, (sp. gr. 1.150), HF.
power.
7.6 Nitric Acid, 70%, (sp. gr. 1.400), HNO .
10.1.1.4 Transfer 2000 6 2 mLof room temperature (19 to
25°C) water intoa2L polypropylene beaker.
10.1.1.5 Measure and record the initial water temperature
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
(T) to the nearest 0.1°C.
i
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, This information taken from the NIOSH Guide to Chemical Hazards, U.S.
MD. Department of Health and Human Services, June 1990.
D5513 − 22
10.1.1.6 Place the beaker in the right front corner of the digestion and remove the vessel with the ruptured membrane
instrumentcavity(asyoufacethefrontoftheinstrument).This fromtheturntableandresumedigestion.Discardthesamplein
positioncloselyapproximatesthepositionofadigestionvessel the removed vessel.
during processing.
11.1.5 Place the vessel in the microwave turntable. Insert
10.1.1.7 Heat the water for the programmed time. the pressure sensing tubing from the pressure controller into
the pressure controller cap assembly and tighten to finger
10.1.1.8 When the heating cycle is complete, immediately
tightness.Besurethatthepressuresensingtubingisfilledwith
removethebeakerfromthecavity,thoroughlystirthewaterto
water (from the pressure controller unit to the
...

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 the previous version. Because
it 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 version
of the standard as published by ASTM is to be considered the official document.
Designation: D5513 − 15 D5513 − 22
Standard Practice for
Microwave Digestion of Industrial Furnace Feed Streams
and Waste for Trace Element Analysis
This standard is issued under the fixed designation D5513; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice describes the multi-stage microwave digestion of typical industrial furnace feed stream materials using nitric,
hydrofluoric, hydrochloric, and boric acids for the subsequent determination of trace metals.
1.2 This practice has been used successfully on samples of coal, coke, cement raw feed materials, and waste-derived fuels
composed primarily of waste paint-related material in preparation for measuring the following trace elements: Ag, As, Ba, Be, Cd,
Cr, Hg, Pb, Sb, and Tl. This practice may be applicable to elements not listed above.
1.3 This practice is also effective for other waste materials (for example, flyash, fly ash, foundry sand, alum process residue,
cement kiln dust, etc.).
1.4 The values stated in SI units are to be regarded as standard. No other Other units of measurement are includedin parentheses
in this standard.standard are informational.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 78.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D5681 Terminology for Waste and Waste Management
2.2 Other Document:
40 CFR 266 Subpart H, Hazardous Waste Burned in Boilers and Industrial Furnaces, Latest Revision
This practice is under the jurisdiction of ASTM Committee D34 on Waste Management and is the direct responsibility of Subcommittee D34.01.06 on Analytical
Methods.
Current edition approved Sept. 1, 2015Oct. 1, 2022. Published September 2015October 2022. Originally approved in 1994. Last previous edition approved in 20092015
as D5513 – 99 (2009).D5513 – 15. DOI: 10.1520/D5513-15.10.1520/D5513-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5513 − 22
3. Terminology
3.1 For definitions of terms used in this practice, refer to Terminology D5681.
4. Summary of Practice
4.1 A weighed portion of the feed stream material is combined with concentrated nitric acid in a polytetrafluoroethylene-lined
digestion vessel, and heated in a microwave digestion unit. Following a programmed heating cycle, the vessel is vented and
specified quantities of hydrofluoric and hydrochloric acids are added, and the mixture undergoes further microwave heating.
Following this heating cycle, the vessel is vented and a specified quantity of boric acid solution is added, and the mixture undergoes
a final microwave heating. Following this final heating cycle, the vessel is vented, the contents are quantitatively transferred to a
volumetric flask, and brought to volume. Typically, the only undissolved material is particulate carbon. If particulate matter is
observed, filtration or centrifugation may be needed. The digested sample is ready for analysis.
5. Significance and Use
5.1 The U.S. Environmental Protection Agency Regulations, 40 CFR 266, require that boilers, cement kilns, and other industrial
furnaces utilizing waste-derived fuel adhere to specific guidelines in assessing potential metals emissions. A common approach for
estimating potential emissions is performing total metals analysis on all feed stream materials. This practice describes a multi-stage
microwave-assisted digestion procedure that solubilizes trace elements for spectroscopic analyses.
6. Apparatus
6.1 Microwave Digestion Unit—Equipped with an automatic turntable, pressure and/or temperature controller, and closed
perfluoroalkoxy (PFA)-lined digestion vessels equipped with pressure relief/rupture membrane fittings or equivalent pressure relief
device. The unit should comply with applicable regional, federal, or state standards for microwave leakage. The user must follow
specific manufacturer’s instructions for system installation.
NOTE 1—The digestion unit used in developing this practice was equipped with a pressure controller, automatic turntable, exhaust fan, and programming
capacity. The unit delivered 1000 W of power at 100 % output. The lined digestion vessels consisted of a high-strength polymeric vessel body and cap,
inner PFA liner and rupture membrane housing, and PFA vent stem. These vessels have a maximum operating pressure of 200 psig. 1378.9 kPa (200 psig).
There are a number of suitable lab grade microwave systems available to the user that meet these minimum specifications. The user must follow specific
manufacturer’s instructions for using digestion vessels.
6.2 Analytical Balance—Capable of weighing to 0.001 g (1 mg).0.001 g (1 mg).
6.3 Labware—High-density volumetric polyethylene or polypropylene flasks/sample containers are recommended for this
practice. The user should be mindful of the quality limitations associated with volumetric non-glass labware.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such
specifications are available. Other grades may be used,used provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean meeting the numerical
requirements of Type II water as defined by SpecificationsSpecification D1193.
7.3 Boric Acid Solution (20 g/L)—Dissolve 20 g of boric acid (H BO ) in water and dilute to 1 L. It may be necessary to place
3 3
solution on a combination hot plate/magnetic stirrer and with the aid of a stir bar, allow the solution to mix under gentle heat until
boric acid is fully in solution.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestionssuggestions on the testing of reagents not
listed by the American Chemical Society, see AnnualAnalar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and
National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D5513 − 22
7.4 Hydrochloric Acid, 37 %, (sp. gr. 1.200), HCl.
7.5 Hydrofluoric Acid, 48 %, (sp. gr. 1.150), HF.
7.6 Nitric Acid, 70 %, (sp. gr. 1.400), HNO .
8. Hazards
8.1 It is recommended that all operations involving concentrated acids be performed in a laboratory fume hood.
8.2 Hydrochloric acid is a highly corrosive chemical that is reactive with metals and most alkaline chemicals. Impervious gloves
and chemical goggles are required for handling. See safety data sheetSafety Data Sheet (SDS) for additional information.
8.3 Hydrofluoric acid is a highly corrosive chemical that is reactive with metals and water or steam. Additionally, HF specifically
attacks silicate glass, making certain fume hood enclosures susceptible to damage. Impervious gloves and chemical goggles are
required for handling. See SDS for additional information.
8.4 Nitric acid is a highly corrosive chemical that is reactive with metals and most organic materials. Impervious gloves and
chemical goggles are required for handling. See SDS for additional information.
8.5 Some samples undergoing microwave digestion can exhibit a rapid pressure rise within the digestion vessel. The potential
exists for this type of sample to rupture the rupture membrane and liberate corrosive gases. Because of this, the microwave unit
must be vented to a fume hood for proper evacuation of vapors.
9. Sample
9.1 Although feed stream materials are generally pulverized powders or liquids, the homogeneity of some feed stream materials
can be uncertain. The laboratory sample should be thoroughly mixed or homogenized prior to withdrawing a portion for analysis.
This practice assumes that non-liquid feed streams are pulverized powders at the time of sample preparation.
NOTE 2—If a non-liquid feed stream material is not in the form of a pulverized powder, it may need to be reduced in particle size to pass through a No.
100 sieve.
10. Calibration and Standardization
10.1 Although equipment manufacturers specify general power output ratings for microwave digestion units, it is important to
verify the actual power output of a specific unit. It is recommended recommended, and may be required in some applications, that
this microwave power check procedure be performed monthly.
10.1.1 Power Check Procedure at 100 % Instrument Power:
10.1.1.1 Remove from the instrument cavity the turntable, drive lug, and all vessels.
10.1.1.2 Adjust the instrument cavity exhaust to minimum air flow (refer to the manufacturer’s instructions).
10.1.1.3 Program the instrument for 4-min 4 min time and 100 % power.
10.1.1.4 Transfer 2000 6 2 mL of room temperature (19 to 25°C)25 °C) water into a 2-L 2 L polypropylene beaker.
10.1.1.5 Measure and record the initial water temperature (T ) to the nearest 0.1°C.0.1 °C.
i
10.1.1.6 Place the beaker in the right front corner of the instrument cavity (as you face the front of the instrument). This position
closely approximates the position of a digestion vessel during processing.
This information taken from the NIOSH Guide to Chemical Hazards, U.S. Depart.Department of Health and Human Services, June 1990.
D5513 − 22
10.1.1.7 Heat the water for the programmed time.
10.1.1.8 When the heating cycle is complete, immediately remove the beaker from the cavity, thoroughly stir the water to ensure
even heat distribution, and measure the final temperature (T ) to the nearest 0.1°C.0.1 °C.
f
10.1.1.9 Calculate the delivered power in accordance with the following equations:
Power watts 5 ΔT 3 35 W/°C (1)
~ ! ~ !
where:
ΔT = T − T .
f i
W/°C =
K 3Cp 3M
t
where:
W = watts,
K = 4.2, the factor for converting thermo-chemical calories/s to joules to watts.
K = 4.2, the factor for converting thermo-chemical calories/s to joules to watts,
−1 −1
Cp = 1.0, the heat capacity for water, cal g degree ,
M = mass of water, g (1 mL H O = 1 g), and
t = time, s.
10.1.1.10 If the calculated power is not within the specifications of the unit, do a second test beginning at 9.1.1.110.1.1.1 for
confirmation before contacting the manufacturer.
11. Procedure
NOTE 3—Many microwave digestion units are capable of handling up to 12twelve digestion vessels at a time. The number of vessels processed affects
the required program settings. The microwave program examples given in Annex A1 and Annex A2Annex A1 and Annex A2 were developed to
accommodate 10ten pressure vessels and have been proven effective in field testing. A maximum pressure of 140 psi 965.27 kPa (140 psi) for a minimum
time at pressure of 10 min
...