ASTM E1645-01(2016)e1
(Practice)Standard Practice for Preparation of Dried Paint Samples by Hotplate or Microwave Digestion for Subsequent Lead Analysis
Standard Practice for Preparation of Dried Paint Samples by Hotplate or Microwave Digestion for Subsequent Lead Analysis
SIGNIFICANCE AND USE
5.1 Paint in buildings and related structures needs to be monitored for lead content in order to determine the potential lead hazard. Hence, effective and efficient methods are required for the preparation of paint samples that may contain lead.
5.2 This practice may be used for the digestion of paint samples that are collected during various lead-hazard control and risk assessment activities associated with lead abatement in and around buildings and related structures. This practice is also suitable for the digestion of paint samples collected from locations such as commercial buildings.
5.3 This practice may be used to prepare samples that have been obtained in order to ensure compliance with laws that govern lead content in paints.
5.4 This practice may be used to prepare samples that have been collected for risk assessment purposes.
5.5 This practice is intended for use with paint samples that are prepared for subsequent analysis by laboratory-based quantitative analytical methods.
SCOPE
1.1 This practice covers the sample preparation procedures for paint samples that are collected during the assessment, management or control of lead hazards.
1.2 This practice describes the digestion procedures using a hot plate or microwave oven or apparatus for paint samples that are to be analyzed for lead content.
1.3 This practice covers the general considerations for quantitative sample extraction for total recoverable lead in dried paint samples (either bulk paint or paint powder) using hot plate or microwave heating techniques, or both.
1.4 This practice contains notes that are explanatory and not part of the mandatory requirements of the standard.
1.5 This practice is based on two NIOSH Methods, 7082 and 7105, and on an EPA standard operating procedure for lead in paint.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 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 and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see 6.1.2, 6.1.2.1, 6.1.2.2, 6.2.4.4, 7.2.1, and 7.2.2.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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´1
Designation: E1645 − 01(Reapproved 2016)
Standard Practice for
Preparation of Dried Paint Samples by Hotplate or
Microwave Digestion for Subsequent Lead Analysis
This standard is issued under the fixed designation E1645; 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.
ε NOTE—Caution statements in 6.1.2, 6.1.2.1, 6.1.2.2, 6.2.4.4, 7.2.1, and 7.2.2 were changed to Warning statements
editorially in January 2016.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice covers the sample preparation procedures
D1129 Terminology Relating to Water
for paint samples that are collected during the assessment,
D1193 Specification for Reagent Water
management or control of lead hazards.
E1605 Terminology Relating to Lead in Buildings
1.2 This practice describes the digestion procedures using a
E1729 Practice for Field Collection of Dried Paint Samples
hotplateormicrowaveovenorapparatusforpaintsamplesthat 3
for Subsequent Lead Determination (Withdrawn 2014)
are to be analyzed for lead content.
2.2 Other Documents:
Environmental ProtectionAgency, Standard Operating Pro-
1.3 This practice covers the general considerations for
cedures for Lead in Paint by Hotplate- or Microwave-
quantitative sample extraction for total recoverable lead in
based Acid Digestions and Atomic Absorption or Induc-
dried paint samples (either bulk paint or paint powder) using
tively Coupled Plasma Emission Spectrometry ; U.S. EPA,
hot plate or microwave heating techniques, or both.
Research Triangle Park, NC (1991). (NTIS No.
1.4 This practice contains notes that are explanatory and not
PB92–114172)
part of the mandatory requirements of the standard.
NIOSH Manual of Analytical Methods, P.M. Eller and M.E.
1.5 This practice is based on two NIOSH Methods, 7082 Cassinelli, Eds., 4th ed., Methods 7082 and 7105; Na-
and7105,andonanEPAstandardoperatingprocedureforlead
tional Institute for Occupational Safety & Health,
in paint. Cincinnati, OH (1994).
1.6 The values stated in SI units are to be regarded as
3. Terminology
standard. No other units of measurement are included in this
3.1 Definitions—For definitions of terms relating to the
standard.
preparation of dried paint samples that are not given here, refer
1.7 This standard does not purport to address all of the
to Terminology D1129, or Terminology E1605.
safety concerns, if any, associated with its use. It is the 3.1.1 batch—a group of field or quality control samples that
responsibility of the user of this standard to establish appro-
are processed together using the same reagents and equipment.
priate safety and health practices and determine the applica-
3.1.2 digestate—an acidified aqueous solution that results
bility of regulatory limitations prior to use. For specific
from digestion of the sample.
precautionary statements, see 6.1.2, 6.1.2.1, 6.1.2.2, 6.2.4.4,
7.2.1, and 7.2.2. 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
This practice is under the jurisdiction of ASTM Committee E06 on Perfor- The last approved version of this historical standard is referenced on
manceofBuildingsandisthedirectresponsibilityofSubcommitteeE06.23onLead www.astm.org.
Hazards Associated with Buildings. Available from National Technical Information Service (NTIS), 5301 Shawnee
Current edition approved Jan. 1, 2016. Published January 2016. Originally Rd., Alexandria, VA 22312, http://www.ntis.gov.
approved in 1994. Last previous edition approved in 2007 as E1465 – 01(2007) Available from NIOSH Publications, 4676 Columbia Parkway, Cincinnati, OH
DOI: 10.1520/E1645-01R16E01. 45226; http://www.cdc.gov/niosh.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E1645 − 01 (2016)
3.1.3 digestion—the sample preparation process that solubi- also suitable for the digestion of paint samples collected from
lizes (extracts) targeted analytes present in the sample, and locations such as commercial buildings.
results in an acidified aqueous solution called the digestate.
5.3 This practice may be used to prepare samples that have
3.1.4 extraction—the dissolution of target analytes from a
been obtained in order to ensure compliance with laws that
solid matrix into a liquid form. During sample digestion, target govern lead content in paints.
analytes are extracted (solubilized) into an acid solution.
5.4 This practice may be used to prepare samples that have
3.1.5 method blank—a sample, devoid of analyte, that is been collected for risk assessment purposes.
analyzed to determine its contribution to the total blank
5.5 This practice is intended for use with paint samples that
(background) reading.
are prepared for subsequent analysis by laboratory-based
3.1.6 non-spiked sample—a sample, devoid of analyte, that
quantitative analytical methods.
is targeted for addition of analyte but is not fortified with all
target analytes prior to sample preparation. 6. Apparatus
3.1.6.1 Discussion—Analysis results for this sample are
6.1 Heating Equipment:
used to correct for background levels in the blank medium that
6.1.1 Electric Hot Plate—suitable for operation at surface
is used for spiked and spiked duplicate samples.
temperatures up to at least 140°C. A temperature of at least
3.1.7 reagent blank—a digestate that reflects the maximum 100°C, as measured by a thermometer placed inside a boro-
silicate glass container (on the hot plate) filled with digestion
treatment given any one sample within a batch of samples,
except that it has no sample placed initially into the digestion solution, should be attainable. (See Note 1.)
vessel. (The same reagents and processing conditions that are
NOTE 1—Provided that the hot plate is capable of handling the extra
applied to field samples within a batch are also applied to the
heating required, use of a 12 to 25-mm (approximately 0.5 to 1-in.) thick
reagent blank.) aluminum plate placed on the burner head can help reduce the presence of
hot spots common to electric hot plates.
3.1.7.1 Discussion—Analysis results from this sample pro-
vide information on the level of potential contamination
6.1.2 Microwave Extraction Apparatus:
resulting from only laboratory sources that are experienced by Warning—Ensure that manufacturer’s safety recommenda-
samples processed within the batch.
tions are followed.
3.1.8 reference material (certified reference material)
NOTE 2—The procedure described is for microwave digestion systems
(CRM)—a material of known composition where the lead level with a temperature control system. Microwave digestion systems that are
equipped only with a pressure control system or lower pressure vessels, or
is certified by the manufacturer.
both, may be used, provided that a prior assessment of the dissolution
3.1.9 sample set—a group of samples (one or more).
efficiency is carried out.
3.1.10 spiked sample or spiked duplicate sample—a blank
6.1.2.1 Microwave Digestion System—designed for closed
medium that contains no purposely added analyte to which a vessel digestion, with power output regulation, fitted with a
known amount of analyte is added before preparation.
temperature control system capable of sensing the temperature
3.1.10.1 Discussion—Analysis results for these samples are to within 62°C, and automatically adjusting the microwave
used to provide information on the precision and accuracy of power output within 2 s. The microwave cavity shall be
the overall process. resistant to chemical attack, and equipped with exhaust venti-
lation for acid vapor protection of the unit and operator. All
electronics shall be protected against corrosion to ensure safe
4. Summary of Practice
operation. Safety interlocks, to shut off magnetron power
4.1 Lead in dried paint samples (chips, powder, etc.) is
output, shall be contained within the oven door opening
solubilized (extracted) by digestion with nitric acid and hydro-
mechanism.
gen peroxide facilitated by heat, or by a mixture of nitric acid
Warning—Domestic (kitchen) microwave ovens shall not
and hydrochloric acid facilitated by microwave energy. (It is
beused,sincethereareverysignificanthazardsassociatedwith
assumed that the paint samples were collected in accordance
their use for the procedure described in this standard. For
withPracticeE1729;however,thispracticecanbeusedforany
example, acid vapors released into the cavity can corrode
collected paint sample.) The lead content of the digested
safety devices that prevent the magnetron from shutting off
sample is then in a form ready for measurement.
when the door is opened, potentially exposing the operator to
microwaveenergy.Also,thefumesgeneratedcanbeextremely
5. Significance and Use
hazardous.
5.1 Paint in buildings and related structures needs to be
NOTE3—Apressurecontrolsystemisalsoveryuseful,sinceitprovides
monitored for lead content in order to determine the potential
asafeguardagainstthepossibilityofsamplelossduetoexcessivepressure
leadhazard.Hence,effectiveandefficientmethodsarerequired
buildup and partial venting of the sample vessels.
for the preparation of paint samples that may contain lead.
6.1.2.2 Lined Sample Vessels—closed, designed for carrying
5.2 This practice may be used for the digestion of paint out microwave digestions, capable of withstanding a tempera-
samples that are collected during various lead-hazard control tureofatleast180°Candwithaninternalvolumeofatleast50
andriskassessmentactivitiesassociatedwithleadabatementin mL.The vessels must be transparent to microwave energy, and
and around buildings and related structures. This practice is vessel liners shall be chemically inert. The vessels must be
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E1645 − 01 (2016)
capable of withstanding high internal pressures (up to at least 7. Sample Treatment
3000 kPa) and temperatures (up to at least 180°C). Vessels
7.1 Sample Preparation:
shallalsobeequippedwithasafetyreliefvalveordiscthatwill
7.1.1 Sample Mass and Area—After analysis, report the
prevent vessel rupture or ejection of the vessel cap. Such 2
final results in area concentration (mg Pb/cm ) or mass
vessels consist of an inner liner and cover made of a micro-
concentration (ppm Pb, percent Pb by mass, or alternative
wave transparent and chemically resistant material (usually a
units). If area concentration is desired, sample areas must be
fluorocarbon polymer such as tetra-fluoromethoxil polymer
provided (by the person submitting the samples) for each paint
(TFM), which contains and isolates the sample solution from a
sample (chip, powder, etc.). The total mass of area concentra-
high strength, outer pressure structure. Other types of sample
tion samples must be determined. Samples may be subsampled
vessels designed to operate at equivalent or higher tempera-
(after grinding and homogenization), depending on the sample
tures or pressures, or both, may be used.
mass.
Warning—For closed vessel designs, the material from
7.1.2 Area Samples—Foreachfieldsample,homogenizethe
which the outer vessels are made is usually not as chemically
dried paint sample (inside the original sample container, if
inert as the liner material. Since the outer vessels provide the
possible) as described in the following:
strength required to withstand the high pressures within the
7.1.2.1 Don a new clean pair of vinyl gloves to perform
inner liners, they must be inspected regularly to check for any
sample handling.
chemical or physical degradation.
7.1.2.2 Remove any large amounts of substrate present in
6.2 Reagents, Glassware and Supplies:
the sample. Exercise care when removing substrate to avoid
6.2.1 Apparatus-Hot Plate Digestion: any losses of paint. If required, use a clean safety razor blade
6.2.1.1 Borosilicate glass beakers, 125-mL or 50-mL with or equivalent tool to aid in substrate removal.
watchglass covers,
7.1.2.3 Determination of Total Collected Sample Mass—
6.2.1.2 Class A borosilicate volumetric flasks, 100–mL and Accurate determination of the collected sample mass is re-
quired to report lead analysis results in terms of area concen-
200–mL,
tration (mass per unit area of paint sample). A complete
6.2.1.3 Class A borosilicate volumetric pipets, volume as
transfer of the sample is required to whatever preweighed
needed,
container is used to hold the sample during mass determination
6.2.1.4 Linear polyethylene bottles with caps, 100–mL,
(for example, weighing boat or weighing paper). Total mass
6.2.1.5 Analytical balance, accurate to 60.1 mg,
shall be made to the nearest 0.1 mg.
6.2.1.6 Glass funnels,
The following precautions shall be observed during deter-
6.2.1.7 Filter paper, and
mination of total mass:
6.2.1.8 Weighing Paper or Weighing Boat.
(1) Total sample mass can be determined either before or
6.2.2 Apparatus-Microwave Digestion:
after sample homogenization. Determination of total sample
6.2.2.1 Centrifuge, with 30 mLpolysulfone centrifuge tubes
mass is generally advisable prior to homogenization when
and polypropylene screw closure,
samples consist of large intact chips that can be easily
6.2.2.2 Class A volumetric and graduated pipets,
transferred without incurring losses. Determination of total
6.2.2.3 Mechanical shaker, and
sample mass is generally advisable after homogenization when
6.2.2.4 Analytical balance, accurate to 60.1 mg.
samples can be homogenized in the original sample collection
6.2.3 Reagents-Hot Plate Digestion:
container and the samples are not large intact chips.
6.2.3.1 Concentrated nitric acid, ACS reagent grade or
NOTE 4—In this case, the sample container should be weighed after
spectrographic grade 16.0 M HNO ,
homogenization.
6.2.3.2 Nitric acid, 10 % (w/v): Add 100 mL concentrated
(2) Any visible traces of paint left in the original container
HNO to 500 mL ASTM Type I water (see Specification
orcontainerusedforhomogenization(ifdifferentfromoriginal
D1193). Dilute to 1 L with ASTM Type I water,
container) may result in bias of the final lead analysis results.
6.2.3.3 Hydrogen peroxide, 30 % H O (w/w);ACS reagent
2 2
Therefore,suchtracesshallbeminimized.Anyvisiblematerial
grade, and
that cannot be transferred shall be documented in sample
6.2.3.4 ASTM Type I water (see Specification D1193).
preparation records.
6.2.4 Reagents-Microwave Digestion:
(3) For sample transfers following homogenization, most
6.2.4.1 Concentrated nitric acid, ACS
...
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.
´1
Designation: E1645 − 01 (Reapproved 2007) E1645 − 01 (Reapproved 2016)
Standard Practice for
Preparation of Dried Paint Samples by Hotplate or
Microwave Digestion for Subsequent Lead Analysis
This standard is issued under the fixed designation E1645; 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.
ε NOTE—Caution statements in 6.1.2, 6.1.2.1, 6.1.2.2, 6.2.4.4, 7.2.1, and 7.2.2 were changed to Warning statements
editorially in January 2016.
1. Scope
1.1 This practice covers the sample preparation procedures for paint samples that are collected during the assessment,
management or control of lead hazards.
1.2 This practice describes the digestion procedures using a hot plate or microwave oven or apparatus for paint samples that
are to be analyzed for lead content.
1.3 This practice covers the general considerations for quantitative sample extraction for total recoverable lead in dried paint
samples (either bulk paint or paint powder) using hot plate or microwave heating techniques, or both.
1.4 The values stated in SI units are to be regarded as the standard.
1.4 This practice contains notes that are explanatory and not part of the mandatory requirements of the standard.
1.5 This practice is based on two NIOSH Methods, 7082 and 7105, and on an EPA standard operating procedure for lead in
paint.
1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7 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 and health practices and determine the applicability of regulatory
limitations prior to use. For specific precautionary statements, see 6.1.2, 6.1.2.1, 6.1.2.2, 6.2.4.4, 7.2.1and , and 7.2.17.2.2.
2. Referenced Documents
2.1 ASTM Standards:
D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
E1605 Terminology Relating to Lead in Buildings
E1729 Practice for Field Collection of Dried Paint Samples for Subsequent Lead Determination (Withdrawn 2014)
2.2 Other Documents:
Environmental Protection Agency, Standard Operating Procedures for Lead in Paint by Hotplate- or Microwave-based Acid
Digestions and Atomic Absorption or Inductively Coupled Plasma Emission Spectrometry ; U.S. EPA, Research Triangle Park,
NC (1991). (NTIS No. PB92–114172)
NIOSH Manual of Analytical Methods, P.M. Eller and M.E. Cassinelli, Eds., 4th ed., Methods 7082 and 7105; National Institute
for Occupational Safety & Health, Cincinnati, OH (1994).
This practice is under the jurisdiction of ASTM Committee E06 on Performance of Buildings and is the direct responsibility of Subcommittee E06.23 on Lead Hazards
Associated with Buildings.
Current edition approved Aug. 1, 2007Jan. 1, 2016. Published August 2007January 2016. Originally approved in 1994. Last previous edition approved in 20012007 as
E1465 – 01(2007) DOI: 10.1520/E1645-01R07.10.1520/E1645-01R16E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Available from National Technical Information Service (NTIS), 5285 Port Royal Rd., Springfield, VA 22161,5301 Shawnee Rd., Alexandria, VA 22312,
http://www.ntis.gov.
Available from NIOSH Publications, 4676 Columbia Parkway, Cincinnati, OH 45226; (800)35–NIOSH.http://www.cdc.gov/niosh.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
E1645 − 01 (2016)
3. Terminology
3.1 Definitions—For definitions of terms relating to the preparation of dried paint samples that are not given here, refer to
Terminology D1129, or Terminology E1605.
3.1.1 batch—a group of field or quality control samples that are processed together using the same reagents and equipment.
3.1.2 digestate—an acidified aqueous solution that results from digestion of the sample.
3.1.3 digestion—the sample preparation process that solubilizes (extracts) targeted analytes present in the sample, and results
in an acidified aqueous solution called the digestate.
3.1.4 extraction—the dissolution of target analytes from a solid matrix into a liquid form. During sample digestion, target
analytes are extracted (solubilized) into an acid solution.
3.1.5 method blank—a sample, devoid of analyte, that is analyzed to determine its contribution to the total blank (background)
reading.
3.1.6 non-spiked sample—a sample, devoid of analyte, that is targeted for addition of analyte but is not fortified with all target
analytes prior to sample preparation.
3.1.6.1 Discussion—
Analysis results for this sample are used to correct for background levels in the blank medium that is used for spiked and spiked
duplicate samples.
3.1.7 reagent blank—a digestate that reflects the maximum treatment given any one sample within a batch of samples, except
that it has no sample placed initially into the digestion vessel. (The same reagents and processing conditions that are applied to
field samples within a batch are also applied to the reagent blank.)
3.1.7.1 Discussion—
Analysis results from this sample provide information on the level of potential contamination resulting from only laboratory
sources that are experienced by samples processed within the batch.
3.1.8 reference material (certified reference material) (CRM)—a material of known composition where the lead level is certified
by the manufacturer.
3.1.9 sample set—a group of samples (one or more).
3.1.10 spiked sample or spiked duplicate sample—a blank medium that contains no purposely added analyte to which a known
amount of analyte is added before preparation.
3.1.10.1 Discussion—
Analysis results for these samples are used to provide information on the precision and accuracy of the overall process.
4. Summary of Practice
4.1 Lead in dried paint samples (chips, powder, etc.) is solubilized (extracted) by digestion with nitric acid and hydrogen
peroxide facilitated by heat, or by a mixture of nitric acid and hydrochloric acid facilitated by microwave energy. (It is assumed
that the paint samples were collected in accordance with Practice E1729; however, this practice can be used for any collected paint
sample.) The lead content of the digested sample is then in a form ready for measurement.
5. Significance and Use
5.1 Paint in buildings and related structures needs to be monitored for lead content in order to determine the potential lead
hazard. Hence, effective and efficient methods are required for the preparation of paint samples that may contain lead.
5.2 This practice may be used for the digestion of paint samples that are collected during various lead-hazard control and risk
assessment activities associated with lead abatement in and around buildings and related structures. This practice is also suitable
for the digestion of paint samples collected from locations such as commercial buildings.
5.3 This practice may be used to prepare samples that have been obtained in order to ensure compliance with laws that govern
lead content in paints.
5.4 This practice may be used to prepare samples that have been collected for risk assessment purposes.
5.5 This practice is intended for use with paint samples that are prepared for subsequent analysis by laboratory-based
quantitative analytical methods.
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E1645 − 01 (2016)
6. Apparatus
6.1 Heating Equipment:
6.1.1 Electric Hot Plate—suitable for operation at surface temperatures up to at least 140°C. A temperature of at least 100°C,
as measured by a thermometer placed inside a borosilicate glass container (on the hot plate) filled with digestion solution, should
be attainable. (See Note 1.)
NOTE 1—Provided that the hot plate is capable of handling the extra heating required, use of a 12 to 25-mm (approximately 0.5 to 1-in.) thick aluminum
plate placed on the burner head can help reduce the presence of hot spots common to electric hot plates.
6.1.2 Microwave Extraction ApparatusMicrowave Extraction Apparatus:
Caution: Warning—Ensure that manufacturer’s safety recommendations are followed. Ensure that manufacturer’s safety
recommendations are followed.
NOTE 2—The procedure described is for microwave digestion systems with a temperature control system. Microwave digestion systems that are
equipped only with a pressure control system or lower pressure vessels, or both, may be used, provided that a prior assessment of the dissolution efficiency
is carried out.
6.1.2.1 Microwave Digestion System—designed for closed vessel digestion, with power output regulation, fitted with a
temperature control system capable of sensing the temperature to within 62°C, and automatically adjusting the microwave power
output within 2 s. The microwave cavity shall be resistant to chemical attack, and equipped with exhaust ventilation for acid vapor
protection of the unit and operator. All electronics shall be protected against corrosion to ensure safe operation. Safety interlocks,
to shut off magnetron power output, shall be contained within the oven door opening mechanism.
Warning—Domestic (kitchen) microwave ovens shall not be used, since there are very significant hazards associated with their
use for the procedure described in this standard. For example, acid vapors released into the cavity can corrode safety devices that
prevent the magnetron from shutting off when the door is opened, potentially exposing the operator to microwave energy. Also,
the fumes generated can be extremely hazardous.Caution: Domestic (kitchen) microwave ovens shall not be used, since there are
very significant hazards associated with their use for the procedure described in this standard. For example, acid vapors released
into the cavity can corrode safety devices that prevent the magnetron from shutting off when the door is opened, potentially
exposing the operator to microwave energy. Also, the fumes generated can be extremely hazardous.
NOTE 3—A pressure control system is also very useful, since it provides a safeguard against the possibility of sample loss due to excessive pressure
buildup and partial venting of the sample vessels.
6.1.2.2 Lined Sample Vessels—closed, designed for carrying out microwave digestions, capable of withstanding a temperature
of at least 180°C and with an internal volume of at least 50 mL. The vessels must be transparent to microwave energy, and vessel
liners shall be chemically inert. The vessels must be capable of withstanding high internal pressures (up to at least 3000 kPa) and
temperatures (up to at least 180°C). Vessels shall also be equipped with a safety relief valve or disc that will prevent vessel rupture
or ejection of the vessel cap. Such vessels consist of an inner liner and cover made of a microwave transparent and chemically
resistant material (usually a fluorocarbon polymer such as tetra-fluoromethoxil polymer (TFM), which contains and isolates the
sample solution from a high strength, outer pressure structure. Other types of sample vessels designed to operate at equivalent or
higher temperatures or pressures, or both, may be used.
Warning—For closed vessel designs, the material from which the outer vessels are made is usually not as chemically inert as
the liner material. Since the outer vessels provide the strength required to withstand the high pressures within the inner liners, they
must be inspected regularly to check for any chemical or physical degradation.Caution: For closed vessel designs, the material
from which the outer vessels are made is usually not as chemically inert as the liner material. Since the outer vessels provide the
strength required to withstand the high pressures within the inner liners, they must be inspected regularly to check for any chemical
or physical 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 with watchglass covers,
6.2.1.2 Class A borosilicate volumetric flasks, 100–mL and 200–mL,
6.2.1.3 Class A borosilicate volumetric pipets, volume as needed,
6.2.1.4 Linear polyethylene bottles with caps, 100–mL,
6.2.1.5 Analytical balance, accurate to 60.1 mg,
6.2.1.6 Glass funnels,
andGlass funnels,
6.2.1.7 Filter paper, and
6.2.1.8 Weighing Paper or Weighing Boat. Weighing Paper or Weighing Boat.
6.2.2 Apparatus-Microwave Digestion:
6.2.2.1 Centrifuge, with 30 mL polysulfone centrifuge tubes and polypropylene screw closure,
6.2.2.2 Class A volumetric and graduated pipets, Class A volumetric and graduated pipets,
6.2.2.3 Mechanical shaker, and
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E1645 − 01 (2016)
6.2.2.4 Analytical balance, accurate to 60.1 mg.
6.2.3 Reagents-Hot Plate Digestion:
6.2.3.1 Concentrated nitric acid, ACS reagent grade or spectrographic grade 16.0 M HNO ,
6.2.3.2 Nitric acid, 10 % (w/v): Add 100 mL concentrated HNO to 500 mL ASTM Type I water (see Specification D1193).
Dilute to 1 L with ASTM Type I water,
6.2.3.3 Hydrogen peroxide, 30 % H O (w/w); ACS reagent grade, and
2 2
6.2.3.4 ASTM Type I water (see Specification D1193).
6.2.4 Reagents-Microwave Digestion:
6.2.4.1 Concentrated nitric acid, ACS reagent grade or spectrographic grade 16.0 M HNO ,
6.2.4.2 Concentrated hydrochloric acid, ACS reagent grade 12.3 M HCl,
6.2.4.3 ASTM Type I water (see Specification D1193), and
6.2.4.4 Extraction Solution—In a 1-L volumetric flask, combine the following in order and mix well: 500 mL ASTM Type I
water, 60 mL concentrated HNO and 180 mL concentrated HCl. Cool to room temperature and dilute to 1 L with ASTM Type
I water. Caution:(Warning—Nitric and hydrochloric acid fumes are toxic. Prepare in a well-ventilated fume hood. Nitric and
hydrochloric acid fumes are toxic. Prepare in a well-ventilated fume hood.)
7. Sample Treatment
7.1 Sample Preparation:
7.1.1 Sample Mass and Area—After analysis, report the final results in area concentration (mg Pb/cm ) or mass concentration
(ppm Pb, percent Pb b
...
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