ASTM E1184-10(2016)

Standard Practice for Determination of Elements by Graphite Furnace Atomic Absorption Spectrometry

SIGNIFICANCE AND USE
4.1 This practice is intended for users who are attempting to establish GF-AAS procedures. It should be helpful for establishing a complete atomic absorption analysis program.
SCOPE
1.1 This practice covers a procedure for the determination of microgram per millilitre (μg/mL) or lower concentrations of elements in solution using a graphite furnace attached to an atomic absorption spectrometer. A general description of the equipment is provided. Recommendations are made for preparing the instrument for measurements, establishing optimum temperature conditions and other criteria which should result in determining a useful calibration concentration range, and measuring and calculating the test solution analyte concentration.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.  
1.3 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. Specific safety hazard statements are given in Section 9.

General Information

• Status: Historical
• Publication Date: 31-Mar-2016
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: E01 - Analytical Chemistry for Metals, Ores, and Related Materials
• Drafting Committee: E01.20 - Fundamental Practices

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E1184 − 10 (Reapproved 2016)
Standard Practice for
Determination of Elements by Graphite Furnace Atomic
Absorption Spectrometry
This standard is issued under the fixed designation E1184; 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 3. Terminology
1.1 This practice covers a procedure for the determination 3.1 RefertoTerminologiesE131andE135forthedefinition
of terms used in this practice.
of microgram per millilitre (µg/mL) or lower concentrations of
elements in solution using a graphite furnace attached to an
3.2 Definitions of Terms Specific to This Standard:
atomic absorption spectrometer. A general description of the
3.2.1 atomization—the formation of ground state atoms that
equipment is provided. Recommendations are made for pre-
absorb radiation from a line emission source. The atomization
paring the instrument for measurements, establishing optimum
process in graphite furnace atomic absorption spectrometry
temperatureconditionsandothercriteriawhichshouldresultin
(GF-AAS) analysis is covered in 6.2.
determining a useful calibration concentration range, and
3.2.2 pyrolysis—the process of heating a specimen to a
measuring and calculating the test solution analyte concentra-
temperature high enough to remove or alter its original matrix,
tion.
butnotsohighastovolatilizetheelementtobemeasured.The
1.2 The values stated in SI units are to be regarded as
purpose of the pyrolysis step in GF-AAS analysis is to remove
standard. The values given in parentheses are for information
or alter the original specimen matrix, thereby reducing or
only.
eliminating possible interferences to the formation of ground
state atoms that are formed when the temperature is increased
1.3 This standard does not purport to address all of the
during the atomization step. Many publications and references
safety concerns, if any, associated with its use. It is the
will refer to pyrolysis as charring or ashing.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3.2.3 pyrolytic graphite coating—alayerofpyrolyticgraph-
bility of regulatory limitations prior to use. Specific safety
ite that coats a graphite tube used in GF-AAS analysis.
hazard statements are given in Section 9.
Pyrolytic graphite is formed by pyrolizing a hydrocarbon, for
example, methane, at 2000°C.
2. Referenced Documents
3.2.4 ramping—a slow, controlled increase of the tempera-
2.1 ASTM Standards:
ture in the graphite tube. Ramping will provide for an efficient
E50Practices for Apparatus, Reagents, and Safety Consid-
but not too rapid removal or decomposition of the specimen
erations for Chemical Analysis of Metals, Ores, and
matrix. Most graphite furnaces allow for ramping during the
Related Materials
drying,pyrolysis,andatomizationsteps.Itisusuallyemployed
E131Terminology Relating to Molecular Spectroscopy
during the drying and pyrolysis steps. However, some instru-
E135Terminology Relating to Analytical Chemistry for
ment manufacturers may recommend ramping during the
Metals, Ores, and Related Materials
atomization step depending on the specimen matrix and the
E406Practice for Using Controlled Atmospheres in Spec-
elementbeingmeasured(forexample,theanalysisofcadmium
trochemical Analysis
or lead in hair or blood). The power supplies for most
D1193Specification for Reagent Water
instruments also allow the rate of the temperature increase to
be varied.
This practice is under the jurisdiction ofASTM Committee E01 on Analytical 4. Significance and Use
ChemistryforMetals,Ores,andRelatedMaterialsandisthedirectresponsibilityof
4.1 Thispracticeisintendedforuserswhoareattemptingto
Subcommittee E01.20 on Fundamental Practices.
establish GF-AAS procedures. It should be helpful for estab-
Current edition approved April 1, 2016. Published May 2016. Originally
approved in 1987. Last previous edition approved in 2010 as E1184–10. DOI:
lishing a complete atomic absorption analysis program.
10.1520/E1184-10R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5. Theory of Atomic Absorption Spectrometry (AAS)
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.1 In flame atomic absorption spectrometry (Flame-AAS),
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. a test solution is aspirated into a flame through which passes
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1184 − 10 (2016)
radiation from a line emission source of the element sought. design. These tubes are available with or without pyrolytic
The radiation of the element sought is absorbed in proportion graphite coating. However, because of increased tube life,
to the concentration of its neutral atoms present in the flame. tubes coated with pyrolytic graphite are commonly used. The
The concentration of the analyte is obtained by comparison to water- cooled unit or atomizer head which holds the graphite
calibrations. tube is constructed in such a way that an inert gas, usually
argon or nitrogen, is passed over, around, or through the
5.2 The theoretical basis for using atomic absorption to
graphite tube to protect it from atmospheric oxidation. The
determine analyte concentration can be found in texts on
heating of all of these atomizers is controlled by power
instrumental analysis in analytical chemistry and in the litera-
supplies which make it possible to heat the graphite tube to
ture.
3000°C in less than 1s. Temperatures and drying, pyrolysis,
and atomization times are controlled by these power supplies
6. Theory of Graphite Furnace Atomic Absorption
(determination of these parameters is covered later in Section
Spectrometry
10).The flow of the inert gas through the atomizer head also is
6.1 Basic Technique—A discrete amount of test solution is
controlled by the power supplies.
heated in a graphite furnace to produce a cloud of neutral
7.2.1 Other types of atomizers and accessories such as the
atoms. Light, emitted by a specific element from a line source
graphite cup, graphite rod, L’vov platform, tantalum filament,
at a specific wavelength, is passed through the cloud and
and tantalum boat have been used and are covered in the
neutralatomsofthissameelementinthecloudabsorbsomeof
literature. With the exception of the L’vov platform, they have
this light. Thus, the intensity of the beam is decreased at the
not enjoyed the widespread and general use that the graphite
wavelengths characteristic of the element. This absorbance of
tube atomizers have. Therefore, they will not be covered in
radiation from the external light source depends on the
detail within this practice.Agood general description of these
population of the neutral atoms and is proportional to the
other units can be found in the literature.
concentration of the element in the test solution.
7.3 Signal Output System—The output signal resulting from
6.2 Graphite Furnace Atomization— Thermodynamic and
theatomizationofaspecimenmaybedisplayedbyastripchart
kinetic theories must be considered to fully understand the
recorder, video display, digital computer, printer, or other
atomization process that takes place in the graphite furnace.
suitable device depending on the electronic capability of the
Jackson (1) and also Campbell and Ottaway (2) provide a
spectrometer employed.
complete discussion of the thermodynamic theory. They also
7.3.1 If a strip chart recorder is used, it must have a full
discuss thermal dissociation of metal oxides, reduction of
scale response of 0.5s or less. Normally, when a strip chart
metaloxides,evaporationofmetaloxidespriortoatomization,
recorderisused,theabsorptionisdeterminedbymeasuringthe
and carbide formation. Several models have been proposed to
peak height of the recorder tracing. This procedure is appro-
explain the theory of kinetic atomization. A search of the
priate because the absorption signal generated by a graphite
literature will find discussions of atomization under increasing
furnaceatomizerusuallyresultsinaverynarrowpeak(absorp-
temperature, and atomization under isothermal conditions (3).
tion versus time). However, some specimen matrices may
Additional discussion and clarification of the kinetic atomiza-
requireinstrumentalparameters(forexample,ramping),which
tion theory is provided by Paveri-Fontana et al. (4).
willresultinbroadabsorptionversustimepeaks.Insuchcases,
peak area measurement may be more appropriate. The instru-
7. Apparatus
ment manufacturer’s manual should be consulted to determine
7.1 Atomic Absorption Spectrometer—Most flame atomic
whichprocedureismostsuitablefortheinstrumentbeingused.
absorption spectrometers manufactured currently can be easily
adapted for graphite furnace analysis.
8. Reagents and Materials
7.1.1 Automatic background correction is necessary for all
8.1 Picogram quantities of some elements can be deter-
spectrometers used with graphite furnaces. When graphite
mined by means of graphite furnace atomization. Therefore,
furnaces are heated to high temperatures, background from
ultra-pure acids and Type I (Specification D1193) water shall
absorption is produced within the graphite tube. Also, small
be used to prepare calibration solutions and test solutions.
amounts of particulate matter in the furnace contribute to the
background signal. Therefore, it is essential to correct or
9. Hazards
compensate for this background.
9.1 Electrical Hazards—The power supplies for graphite
7.2 Electrothermal Atomizers—The most commonly used
furnaces require high-voltage (greater than 200V) electrical
electrothermal atomizer is the graphite tube furnace. This
service. Electrical power shall be supplied as determined from
atomizer consists of a graphite tube positioned in a water-
load requirements in accordance with the latest revision of the
cooled unit designed to be placed in the optical path of the
National Electrical Code. The recommendations of the equip-
spectrometer so that the light from the hollow cathode lamp
ment manufacturers and local engineers should be followed in
passes through the center of the tube. The tubes vary in size
designing the electrical service.
dependinguponaparticularinstrumentmanufacturer’sfurnace
9.2 Compressed Gas Hazard—The inert or non-oxidizing
atmosphere required in the graphite furnace during heating
cycles is usually maintained by using argon or nitrogen gas
The boldface numbers in parentheses refer to a list of references at the end of
this standard. delivered from portable gas cylinders.
E1184 − 10 (2016)
9.2.1 Sufficient space shall be provided for the cylinders, ally controlled heating stages for drying, pyrolysis, and atomi-
which shall be kept in a vertical position and always well zation. The means to control the times and temperatures of
secured. They shall not be used or stored near burners, hot these stages will vary with instrumentation. Most manufactur-
plates, or in any area where the temperature exceeds 52ºC ers provide a listing of the parameters required for the graphite
(125ºF).Thecontentsshallbeidentifiedwithlabelsorstencils furnace analysis of numerous elements in the most commonly
and color coding. encountered matrices. The recommended parameters for a
9.2.2 Two-stage regulators with pressure gages should be particularelementshouldbeverifiedforthespecificinstrument
used as part of the basic flow system to deliver required being used with an appropriate solution. Also, for sample
cylinder gas to the instrument at a reduced pressure. Practice matrices that differ from those printed in the manufacturer’s
E406 and the manufacturer’s instructions should be followed list, the most appropriate time and temperature setting for each
with regard to the types of regulators, flow-metering valves, stage must be calculated or determined experimentally (see
and tubing for gas transport when designing a gas delivery 10.1.1).
system.
NOTE 1—Ramping is normally used during the drying and pyrolysis
9.2.3 Reserve gas cylinders should not be stored in the
stages. Some procedures may also recommend that ramping be used
laboratory area. Gas storage areas shall be adequately duringtheatomizationstage,dependinguponthespecimenmatrixandthe
element being measured. Refer to the instrument manufacturer’s manual
ventilated, fire-resistant, located away from sources of ignition
of the particular instrument for the recommended ramp rates, if any, for
or excessive heat, and dry. All cylinders shall be chained in
the type of solution being analyzed.
placeorplacedinpartitionedcellstopreventthemfromfalling
10.1.1 Drying—The drying stage is a low temperature stage
over. In all cases, storage areas shall comply with local, state,
in which the graphite tube is heated to a temperature high
andmunicipalrequirementsaswellaswiththestandardsofthe
enoughtoevaporate,butnotboil,anysolvent.Theidealdrying
Compressed GasAssociation and the National Fire Prevention
temperature would be one just below the boiling point of the
Association. Access to gas storage areas should be limited to
solvent. Specimen spattering may occur if the temperature is
authorized personnel.
raised above the boiling point before evaporation is complete.
9.3 Chemical Hazard—PracticeE50shouldbeconsultedfor
The time, in seconds, required to completely dry a specimen
recommendations and precautions concerning chemical haz-
may be calculated by multiplying 1.5times to 2times the
ards.
volume of the specimen, measured in microlitres (µL). For
9.4 Ventilation—Asmall hood is required to carry away any example,a10-µLspecimenwouldrequireadryingtimeof15s
toxic fumes that may result from the atomization process. to 20s. If an auto-sampling device is to be used, adjust it to
Follow the manufacturer’s instructions for proper hood instal- deposit the desired volume (in microlitres) in the graphite tube
lation. (see Note 2). Deposit a measured amount of the reagent blank
solution, prepared as directed in 11.1, in the graphite tube.The
9.5 Laboratory—The laboratory in which the graphite fur-
volume should be identical to the test solution volume (see
nace is operated shall be kept as clean as possible. Any
Note 2). Cycle through the heating stages and adjust the
proceduresthatmayproduceanatmospherethatiscorrosiveto
readout system of the instrument to read zero absorbance
the instrumentation or detrimental to the analysis of the
during the atomization of the reagent
...

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: E1184 − 10 E1184 − 10 (Reapproved 2016)
Standard Practice for
Determination of Elements by Graphite Furnace Atomic
Absorption Spectrometry
This standard is issued under the fixed designation E1184; 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 covers a procedure for the determination of microgram per millilitre (μg/mL) or lower concentrations of
elements in solution using a graphite furnace attached to an atomic absorption spectrometer. A general description of the equipment
is provided. Recommendations are made for preparing the instrument for measurements, establishing optimum temperature
conditions and other criteria which should result in determining a useful calibration concentration range, and measuring and
calculating the test solution analyte concentration.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.3 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. Specific safety hazard statements are given in Section 9.
2. Referenced Documents
2.1 ASTM Standards:
E50 Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
E131 Terminology Relating to Molecular Spectroscopy
E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
E406 Practice for Using Controlled Atmospheres in Spectrochemical Analysis
D1193 Specification for Reagent Water
3. Terminology
3.1 Refer to Terminologies E131 and E135 for the definition of terms used in this practice.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 atomization—the formation of ground state atoms that absorb radiation from a line emission source. The atomization
process in graphite furnace atomic absorption spectrometry (GF-AAS) analysis is covered in 6.2.
3.2.2 pyrolysis—the process of heating a specimen to a temperature high enough to remove or alter its original matrix, but not
so high as to volatilize the element to be measured. The purpose of the pyrolysis step in GF-AAS analysis is to remove or alter
the original specimen matrix, thereby reducing or eliminating possible interferences to the formation of ground state atoms that
are formed when the temperature is increased during the atomization step. Many publications and references will refer to pyrolysis
as charring or ashing.
3.2.3 pyrolytic graphite coating—a layer of pyrolytic graphite that coats a graphite tube used in GF-AAS analysis. Pyrolytic
graphite is formed by pyrolizing a hydrocarbon, for example, methane, at 2000 °C.
3.2.4 ramping—a slow, controlled increase of the temperature in the graphite tube. Ramping will provide for an efficient but not
too rapid removal or decomposition of the specimen matrix. Most graphite furnaces allow for ramping during the drying, pyrolysis,
and atomization steps. It is usually employed during the drying and pyrolysis steps. However, some instrument manufacturers may
This practice is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility of
Subcommittee E01.20 on Fundamental Practices.
Current edition approved June 1, 2010April 1, 2016. Published August 2010May 2016. Originally approved in 1987. Last previous edition approved in 20022010 as
E1184 – 02.E1184 – 10. DOI: 10.1520/E1184-10.10.1520/E1184-10R16.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1184 − 10 (2016)
recommend ramping during the atomization step depending on the specimen matrix and the element being measured (for example,
the analysis of cadmium or lead in hair or blood). The power supplies for most instruments also allow the rate of the temperature
increase to be varied.
4. Significance and Use
4.1 This practice is intended for users who are attempting to establish GF-AAS procedures. It should be helpful for establishing
a complete atomic absorption analysis program.
5. Theory of Atomic Absorption Spectrometry (AAS)
5.1 In flame atomic absorption spectrometry (Flame-AAS), a test solution is aspirated into a flame through which passes
radiation from a line emission source of the element sought. The radiation of the element sought is absorbed in proportion to the
concentration of its neutral atoms present in the flame. The concentration of the analyte is obtained by comparison to calibrations.
5.2 The theoretical basis for using atomic absorption to determine analyte concentration can be found in texts on instrumental
analysis in analytical chemistry and in the literature.
6. Theory of Graphite Furnace Atomic Absorption Spectrometry
6.1 Basic Technique—A discrete amount of test solution is heated in a graphite furnace to produce a cloud of neutral atoms.
Light, emitted by a specific element from a line source at a specific wavelength, is passed through the cloud and neutral atoms of
this same element in the cloud absorb some of this light. Thus, the intensity of the beam is decreased at the wavelengths
characteristic of the element. This absorbance of radiation from the external light source depends on the population of the neutral
atoms and is proportional to the concentration of the element in the test solution.
6.2 Graphite Furnace Atomization— Thermodynamic and kinetic theories must be considered to fully understand the
atomization process that takes place in the graphite furnace. Jackson (1) and also Campbell and Ottaway (2) provide a complete
discussion of the thermodynamic theory. They also discuss thermal dissociation of metal oxides, reduction of metal oxides,
evaporation of metal oxides prior to atomization, and carbide formation. Several models have been proposed to explain the theory
of kinetic atomization. A search of the literature will find discussions of atomization under increasing temperature, and atomization
under isothermal conditions (3). Additional discussion and clarification of the kinetic atomization theory is provided by
Paveri-Fontana et al. (4).
7. Apparatus
7.1 Atomic Absorption Spectrometer—Most flame atomic absorption spectrometers manufactured currently can be easily
adapted for graphite furnace analysis.
7.1.1 Automatic background correction is necessary for all spectrometers used with graphite furnaces. When graphite furnaces
are heated to high temperatures, background from absorption is produced within the graphite tube. Also, small amounts of
particulate matter in the furnace contribute to the background signal. Therefore, it is essential to correct or compensate for this
background.
7.2 Electrothermal Atomizers—The most commonly used electrothermal atomizer is the graphite tube furnace. This atomizer
consists of a graphite tube positioned in a water-cooled unit designed to be placed in the optical path of the spectrometer so that
the light from the hollow cathode lamp passes through the center of the tube. The tubes vary in size depending upon a particular
instrument manufacturer’s furnace design. These tubes are available with or without pyrolytic graphite coating. However, because
of increased tube life, tubes coated with pyrolytic graphite are commonly used. The water- cooled unit or atomizer head which
holds the graphite tube is constructed in such a way that an inert gas, usually argon or nitrogen, is passed over, around, or through
the graphite tube to protect it from atmospheric oxidation. The heating of all of these atomizers is controlled by power supplies
which make it possible to heat the graphite tube to 3000 °C in less than 1 s. Temperatures and drying, pyrolysis, and atomization
times are controlled by these power supplies (determination of these parameters is covered later in Section 10). The flow of the
inert gas through the atomizer head also is controlled by the power supplies.
7.2.1 Other types of atomizers and accessories such as the graphite cup, graphite rod, L’vov platform, tantalum filament, and
tantalum boat have been used and are covered in the literature. With the exception of the L’vov platform, they have not enjoyed
the widespread and general use that the graphite tube atomizers have. Therefore, they will not be covered in detail within this
practice. A good general description of these other units can be found in the literature.
7.3 Signal Output System—The output signal resulting from the atomization of a specimen may be displayed by a strip chart
recorder, video display, digital computer, printer, or other suitable device depending on the electronic capability of the spectrometer
employed.
The boldface numbers in parentheses refer to a list of references at the end of this standard.
E1184 − 10 (2016)
7.3.1 If a strip chart recorder is used, it must have a full scale response of 0.5 s or less. Normally, when a strip chart recorder
is used, the absorption is determined by measuring the peak height of the recorder tracing. This procedure is appropriate because
the absorption signal generated by a graphite furnace atomizer usually results in a very narrow peak (absorption versus time).
However, some specimen matrices may require instrumental parameters (for example, ramping), which will result in broad
absorption versus time peaks. In such cases, peak area measurement may be more appropriate. The instrument manufacturer’s
manual should be consulted to determine which procedure is most suitable for the instrument being used.
8. Reagents and Materials
8.1 Picogram quantities of some elements can be determined by means of graphite furnace atomization. Therefore, ultra-pure
acids and Type I (Specification D1193) water shall be used to prepare calibration solutions and test solutions.
9. Hazards
9.1 Electrical Hazards—The power supplies for graphite furnaces require high-voltage (greater than 200 V) electrical service.
Electrical power shall be supplied as determined from load requirements in accordance with the latest revision of the National
Electrical Code. The recommendations of the equipment manufacturers and local engineers should be followed in designing the
electrical service.
9.2 Compressed Gas Hazard—The inert or non-oxidizing atmosphere required in the graphite furnace during heating cycles is
usually maintained by using argon or nitrogen gas delivered from portable gas cylinders.
9.2.1 Sufficient space shall be provided for the cylinders, which shall be kept in a vertical position and always well secured.
They shall not be used or stored near burners, hot plates, or in any area where the temperature exceeds 52 ºC (125 ºF). The contents
shall be identified with labels or stencils and color coding.
9.2.2 Two-stage regulators with pressure gages should be used as part of the basic flow system to deliver required cylinder gas
to the instrument at a reduced pressure. Practice E406 and the manufacturer’s instructions should be followed with regard to the
types of regulators, flow-metering valves, and tubing for gas transport when designing a gas delivery system.
9.2.3 Reserve gas cylinders should not be stored in the laboratory area. Gas storage areas shall be adequately ventilated,
fire-resistant, located away from sources of ignition or excessive heat, and dry. All cylinders shall be chained in place or placed
in partitioned cells to prevent them from falling over. In all cases, storage areas shall comply with local, state, and municipal
requirements as well as with the standards of the Compressed Gas Association and the National Fire Prevention Association.
Access to gas storage areas should be limited to authorized personnel.
9.3 Chemical Hazard—Practice E50 should be consulted for recommendations and precautions concerning chemical hazards.
9.4 Ventilation—A small hood is required to carry away any toxic fumes that may result from the atomization process. Follow
the manufacturer’s instructions for proper hood installation.
9.5 Laboratory—The laboratory in which the graphite furnace is operated shall be kept as clean as possible. Any procedures
that may produce an atmosphere that is corrosive to the instrumentation or detrimental to the analysis of the specimen should be
removed from the laboratory.
9.6 Laboratory Apparatus—It is imperative that all laboratory apparatus and containers used in the preparation of calibration
and test solutions be acid cleaned. All laboratory ware, including plastic tips used on micropipets for the transfer of calibration
solutions and test solutions to the graphite tube, should be acid rinsed before being used. Once laboratory ware is acid rinsed, all
of the items that come in contact with analytical solutions shall be isolated from subsequent contact with fingers, clothing, bench
tops, etc.
9.7 Magnetic Background Correction—If the graphite furnace atomic absorption unit is provided with a background correction
that does or can produce a magnetic field, the unit should not be operated by an individual who wears, internally or externally, a
medical device such as a pacemaker, that can be affected by the magnetic field, without the approval of the prescribing or installing
physician, or both. In addition an appropriate warning sign should warn visitors of the magnetic field.
10. Preparation of Apparatus
10.1 Graphite Furnace Parameters—All graphite furnaces are resistance-heated by power supplies that provide individually
controlled heating stages for drying, pyrolysis, and atomization. The means to control the times and temperatures of these stages
will vary with instrumentation. Most manufacturers provide a listing of the parameters required for the graphite furnace analysis
of numerous elements in the most commonly encountered matrices. The recommended parameters for a
...