ASTM D7740-11(2016)
(Practice)Standard Practice for Optimization, Calibration, and Validation of Atomic Absorption Spectrometry for Metal Analysis of Petroleum Products and Lubricants
Standard Practice for Optimization, Calibration, and Validation of Atomic Absorption Spectrometry for Metal Analysis of Petroleum Products and Lubricants
SIGNIFICANCE AND USE
5.1 Accurate elemental analysis of petroleum products and lubricants is necessary for the determination of chemical properties, which are used to establish compliance with commercial and regulatory specifications.
5.2 Atomic Absorption Spectrometry (AAS) is one of the most widely used analytical techniques in the oil industry for elemental analysis. There are at least twelve Standard Test Methods published by ASTM D02 Committee on Petroleum Products and Lubricants for such analysis. See Table 1.
5.3 The advantage of using an AAS analysis include good sensitivity for most metals, relative freedom from interferences, and ability to calibrate the instrument based on elemental standards irrespective of their elemental chemical forms. Thus, the technique has been a method of choice in most of the oil industry laboratories. In many laboratories, AAS has been superseded by a superior ICP-AES technique (see Practice D7260).
5.4 Some of the ASTM AAS Standard Test Methods have also been issued by other standard writing bodies as technically equivalent standards. See Table 2. (A) Excerpted from ASTM MNL44, Guide to ASTM Test Methods for the Analysis of Petroleum Products and Lubricants, 2nd edition, Ed., Nadkarni, R. A. Kishore, ASTM International, West Conshohocken, PA, 2007.
SCOPE
1.1 This practice covers information on the calibration and operational guidance for elemental measurements using atomic absorption spectrometry (AAS).
1.1.1 AAS Related Standards—Test Methods D1318, D3237, D3340, D3605, D3831, D4628, D5056, D5184, D5863, D6732; Practices D7260 and D7455; and Test Methods D7622 and D7623.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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.
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Designation: D7740 − 11 (Reapproved 2016)
Standard Practice for
Optimization, Calibration, and Validation of Atomic
Absorption Spectrometry for Metal Analysis of Petroleum
Products and Lubricants
This standard is issued under the fixed designation D7740; 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 D4057 Practice for Manual Sampling of Petroleum and
Petroleum Products
1.1 This practice covers information on the calibration and
D4177 Practice for Automatic Sampling of Petroleum and
operationalguidanceforelementalmeasurementsusingatomic
Petroleum Products
absorption spectrometry (AAS).
D4307 Practice for Preparation of Liquid Blends for Use as
1.1.1 AAS Related Standards—Test Methods D1318,
Analytical Standards
D3237, D3340, D3605, D3831, D4628, D5056, D5184,
D4628 Test Method for Analysis of Barium, Calcium,
D5863,D6732;PracticesD7260andD7455;andTestMethods
Magnesium, and Zinc in Unused Lubricating Oils by
D7622 and D7623.
Atomic Absorption Spectrometry
1.2 The values stated in SI units are to be regarded as
D5056 Test Method for Trace Metals in Petroleum Coke by
standard. No other units of measurement are included in this
Atomic Absorption
standard.
D5184 Test Methods for Determination of Aluminum and
1.3 This standard does not purport to address all of the
Silicon in Fuel Oils by Ashing, Fusion, Inductively
safety concerns, if any, associated with its use. It is the Coupled Plasma Atomic Emission Spectrometry, and
responsibility of the user of this standard to establish appro-
Atomic Absorption Spectrometry
priate safety and health practices and determine the applica- D5863 Test Methods for Determination of Nickel,
bility of regulatory limitations prior to use.
Vanadium, Iron, and Sodium in Crude Oils and Residual
Fuels by Flame Atomic Absorption Spectrometry
2. Referenced Documents
D6299 Practice for Applying Statistical Quality Assurance
and Control Charting Techniques to Evaluate Analytical
2.1 ASTM Standards:
Measurement System Performance
D1318 Test Method for Sodium in Residual Fuel Oil (Flame
D6732 Test Method for Determination of Copper in Jet
Photometric Method)
Fuels by Graphite Furnace Atomic Absorption Spectrom-
D3237 TestMethodforLeadinGasolinebyAtomicAbsorp-
etry
tion Spectroscopy
D6792 Practice for Quality System in Petroleum Products
D3340 Test Method for Lithium and Sodium in Lubricating
and Lubricants Testing Laboratories
Greases by Flame Photometer (Withdrawn 2013)
D7260 Practice for Optimization, Calibration, and Valida-
D3605 Test Method for Trace Metals in Gas Turbine Fuels
tion of Inductively Coupled Plasma-Atomic Emission
by Atomic Absorption and Flame Emission Spectroscopy
Spectrometry (ICP-AES) for ElementalAnalysis of Petro-
D3831 Test Method for Manganese in Gasoline By Atomic
leum Products and Lubricants
Absorption Spectroscopy
D7455 Practice for Sample Preparation of Petroleum and
Lubricant Products for Elemental Analysis
This practice is under the jurisdiction ofASTM Committee D02 on Petroleum
D7622 Test Method for Total Mercury in Crude Oil Using
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
Combustion and Direct Cold Vapor Atomic Absorption
mittee D02.03 on Elemental Analysis.
Method with Zeeman Background Correction
Current edition approved April 1, 2016. Published May 2016. Originally
approved in 2011. Last previous edition approved in 2011 as D7740 – 11. DOI: D7623 Test Method for Total Mercury in Crude Oil Using
10.1520/D7740-11R16.
Combustion-Gold Amalgamation and Cold Vapor Atomic
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Absorption Method
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7740 − 11 (2016)
3. Terminology 3.1.16 monochromator, n—device that isolates a single
atomic resonance line from the line spectrum emitted by the
3.1 Definitions:
hollow cathode lamp, excluding all other wavelengths.
3.1.1 absorbance, n—logarithmtothebase10oftheratioof
3.1.17 nebulizer, n—device that generates an aerosol by
the reciprocal of the transmittance.
flowing a liquid over a surface that contains an orifice from
3.1.2 atomic absorption spectrometry, n—analytical tech-
which gas flows at a high velocity.
nique for measuring metal content of solutions, based on a
3.1.18 NIST, n—National Institute of Standards and
combination of flame source, hollow cathode lamp,
Technology, Gaithersburg, MD. Formerly known as National
photomultiplier, and a readout device.
Bureau of Standards.
3.1.3 atomizer, n—usually a flame source used to decom-
3.1.19 precision, n—closeness of agreement between test
pose the chemical constituents in a solution to its elemental
results obtained under prescribed conditions.
components.
3.1.20 quality assurance, n—system of activities, the pur-
3.1.4 blank, n—solutionwhichissimilarincompositionand
pose of which is to provide to the producer and user of a
contentstothesamplesolutionbutdoesnotcontaintheanalyte
product, measurement, or service the assurance that it meets
being measured.
the defined standards of quality with a stated level of confi-
3.1.5 burner, n—flamedeviceusedtoatomizetheanalyteby dence.
burning in a high temperature flame mixed of a fuel and an
3.1.21 quality control, n—planned system of activities
oxidant.
whose purpose is to provide a level of quality that meets the
needs of users; also the uses of such a system.
3.1.6 calibration, n—process by which the relationship
between signal intensity and elemental concentration is deter-
3.1.22 quality control sample, n—for use in quality assur-
mined for a specific element analysis.
ance program to determine and monitor the precision and
stability of a measurement system; a stable and homogenous
3.1.7 calibration curve, n—plot of signal intensity versus
material having physical or chemical properties, or both,
elemental concentration using data obtained by making mea-
similar to those of typical samples tested by the analytical
surements with standards.
measurement system.
3.1.8 calibration standard, n—material with a certified
3.1.22.1 Discussion—This material should be properly
value for a relevant property, issued by or traceable to a
stored to ensure sample integrity, and is available in sufficient
national organization such as NIST, and whose properties are
quantity for repeated long term testing.
known with sufficient accuracy to permit its use to evaluate the
3.1.23 reference material, n—material with accepted refer-
same property of another sample.
ence value(s), accompanied by an uncertainty at a stated level
3.1.9 certified reference material, n—reference material one
of confidence for desired properties, which may be used for
or more of whose property values are certified by a technically
calibration or quality control purposes in the laboratory.
validprocedure,accompaniedbyatraceablecertificateorother
3.1.24 refractory elements, n—elements forming difficult-
documentation which is issued by a certifying body.
to-dissociate oxides during combustion.
3.1.10 check standard, n—material having an assigned
3.1.25 repeatability, n—difference between two test results,
(known) value (reference value) used to determine the accu-
obtained by the same operator with the same apparatus under
racy of the measurement system or instrument.
constant operating conditions on identical test material would,
3.1.10.1 Discussion—This practice is not used to calibrate
in the long term and correct operation of the test method,
the measurement instrument or system.
exceed the values given only in one case in twenty.
3.1.11 detection limit, n—concentration of an analyte that
3.1.26 reproducibility, n—difference between two single
resultsinasignalintensitythatissomemultiple(typicallytwo)
and independent results, obtained by different operators work-
times the standard deviation of the background intensity at the
ingindifferentlaboratoriesonidenticaltestmaterials,wouldin
measurement wavelength.
the long run, in the normal and correct operation of the test
method, exceed the values given only one case in twenty.
3.1.12 dilution factor, n—ratio of sample weight of the
aliquot taken to the final diluted volume of its solution. 3.1.27 spectrometer, n—instrument used to measure the
emission or absorption spectrum emitted by a species in the
3.1.12.1 Discussion—The dilution factor is used to multiply
vaporized sample.
the observed reading and obtain the actual concentration of the
analyte in the original sample.
3.1.28 spectrum, n—arrayofthecomponentsofanemission
or absorption arranged in the order of some varying character-
3.1.13 graphite furnace, n—electrothermal device for atom-
istics such as wavelength, mass, or energy.
izing the metal constituents.
3.1.29 standard reference material, n—trademark for refer-
3.1.14 hollow cathode lamp, n—device consisting of a
ence materials certified by NIST.
quartz envelope containing a cathode of the metal to be
determined and a suitable anode.
4. Summary of Practice
3.1.15 hydride generation, n—device to atomize some met- 4.1 An Atomic Absorption Spectrometer (AAS) is used to
als which form gaseous hydrides. determine the metal composition of various liquid matrices.
D7740 − 11 (2016)
Although usually AAS is done using a flame to atomize the 6.1.2 Ionization Interferences—When the flame has enough
metals, graphite furnace (GF-AAS) or cold vapor (CV-AAS) energy to cause the removal of an electron from the atom,
may also be used for metals at very low levels of concentration creating an ion, ionization interference can occur. They can be
or some elements not amenable to flame atomization. This controlledbyadditionofanexcessofaneasilyionizedelement
practice summarizes the protocols to be followed during to both samples and standards. Normally alkali metals which
calibration and verification of the instrument performance. have very low ionization potentials are used.
6.1.3 Matrix Interferences—These can cause either a sup-
5. Significance and Use
pression or enhancement of the analyte signal. Matrix interfer-
ences occur when the physical characteristics – viscosity,
5.1 Accurate elemental analysis of petroleum products and
burning characteristics, surface tension – of the sample and
lubricants is necessary for the determination of chemical
standard differ considerably. To compensate for the matrix
properties, which are used to establish compliance with com-
interferences, the matrix components in the sample and stan-
mercial and regulatory specifications.
dard should be matched as closely as possible. Matrix inter-
5.2 Atomic Absorption Spectrometry (AAS) is one of the
ferences can also be controlled by diluting the sample solution
most widely used analytical techniques in the oil industry for
until the effect of dissolved salts or acids is negligible.
elemental analysis. There are at least twelve Standard Test
Sometimes, the method of standard addition is used to over-
Methods published by ASTM D02 Committee on Petroleum
come this interference. See 6.2.
Products and Lubricants for such analysis. See Table 1.
6.1.4 Emission Interferences—At high analyte
5.3 The advantage of using an AAS analysis include good
concentrations, the atomic absorption analysis for highly emis-
sensitivity for most metals, relative freedom from
sive elements sometimes exhibits poor analytical precision, if
interferences, and ability to calibrate the instrument based on
the emission signal falls within the spectral bandpass being
elemental standards irrespective of their elemental chemical
used. This interference can be compensated for by decreasing
forms.Thus,thetechniquehasbeenamethodofchoiceinmost
the slit width, increasing the lamp current, diluting the sample,
of the oil industry laboratories. In many laboratories,AAS has
and / or using a cooler flame.
been superseded by a superior ICP-AES technique (see Prac-
6.1.5 Spectral Interferences—When an absorbing wave-
tice D7260).
length of an element present in the sample but not being
determined falls within the bandwidth of the absorption line of
5.4 Some of the ASTM AAS Standard Test Methods have
the element of interest a spectral interference can occur. An
alsobeenissuedbyotherstandardwritingbodiesastechnically
interference by other atoms can occur when there is a sufficient
equivalent standards. See Table 2.
overlapping between radiation and emitted by the excited
6. Interferences
atoms and other absorbing atoms. Usually the bandwidth is
much wider than the width of the emission and absorption
6.1 Although over 70 elements can be determined by AAS
lines. Thus, interferences by other atoms are fortunately quite
usually with a precision of 1-3 % and with detection limits of
limited inAAS.The interference can result in erroneously high
the order of sub-mg/kg levels, and with little or no atomic
results. This can be overcome by using a smaller slit or
spectral interference. However, there are several types of
selecting an alternate wavelength.
interferences possible: chemical, ionization, matrix, emission,
6.1.6 Background Absorption Interferences—There are two
spectral, and background absorption interferences. Since these
causes of background absorption: light scattering by particles
interferences are well-defined, it is easy to eliminate or
intheflameandmolecularabsorptionoflightfromthelampby
compensate for them. See Table 3.
molecules in the flame. This interference cannot be corrected
6.1.1 Chemical Interferences—If the sample for analysis
with standard addition method. The most common way to
contains a thermally stable compound with the analyte that is
compensate for background absorption is to use a background
not totally decomposed by the energy of the flame, a chemical
corrector which utilizes a continuum source.
interference exists. They can normally be overcome or con-
trolled by using a higher temperature flame or addition of a 6.2 Standard Addition Method—One way of dealing with
releasing agent to the sample and standard solutions. some of the interferences in the AAS methods is to use a
TABLE 1 Applications of AAS for Metal Analysis of Petroleum Products and Lubricants
ASTM Test Method Matrix Elements Determined
D1318 Residual Fuel Oil Sodium
...
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: D7740 − 11 D7740 − 11 (Reapproved 2016)
Standard Practice for
Optimization, Calibration, and Validation of Atomic
Absorption Spectrometry for Metal Analysis of Petroleum
Products and Lubricants
This standard is issued under the fixed designation D7740; 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 information on the calibration and operational guidance for elemental measurements using atomic
absorption spectrometry (AAS).
1.1.1 AAS Related Standards—Test Methods D1318, D3237, D3340, D3605, D3831, D4628, D5056, D5184, D5863, D6732;
Practices D7260 and D7455; and Test Methods D7622 and D7623.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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.
2. Referenced Documents
2.1 ASTM Standards:
D1318 Test Method for Sodium in Residual Fuel Oil (Flame Photometric Method)
D3237 Test Method for Lead in Gasoline by Atomic Absorption Spectroscopy
D3340 Test Method for Lithium and Sodium in Lubricating Greases by Flame Photometer (Withdrawn 2013)
D3605 Test Method for Trace Metals in Gas Turbine Fuels by Atomic Absorption and Flame Emission Spectroscopy
D3831 Test Method for Manganese in Gasoline By Atomic Absorption Spectroscopy
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D4628 Test Method for Analysis of Barium, Calcium, Magnesium, and Zinc in Unused Lubricating Oils by Atomic Absorption
Spectrometry
D5056 Test Method for Trace Metals in Petroleum Coke by Atomic Absorption
D5184 Test Methods for Determination of Aluminum and Silicon in Fuel Oils by Ashing, Fusion, Inductively Coupled Plasma
Atomic Emission Spectrometry, and Atomic Absorption Spectrometry
D5863 Test Methods for Determination of Nickel, Vanadium, Iron, and Sodium in Crude Oils and Residual Fuels by Flame
Atomic Absorption Spectrometry
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6732 Test Method for Determination of Copper in Jet Fuels by Graphite Furnace Atomic Absorption Spectrometry
D6792 Practice for Quality System in Petroleum Products and Lubricants Testing Laboratories
D7260 Practice for Optimization, Calibration, and Validation of Inductively Coupled Plasma-Atomic Emission Spectrometry
(ICP-AES) for Elemental Analysis of Petroleum Products and Lubricants
D7455 Practice for Sample Preparation of Petroleum and Lubricant Products for Elemental Analysis
This practice is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.03 on Elemental Analysis.
Current edition approved July 1, 2011April 1, 2016. Published August 2011May 2016. Originally approved in 2011. Last previous edition approved in 2011 as D7740 – 11.
DOI: 10.1520/D7740–11.10.1520/D7740-11R16.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7740 − 11 (2016)
D7622 Test Method for Total Mercury in Crude Oil Using Combustion and Direct Cold Vapor Atomic Absorption Method with
Zeeman Background Correction
D7623 Test Method for Total Mercury in Crude Oil Using Combustion-Gold Amalgamation and Cold Vapor Atomic Absorption
Method
D7740 − 11 (2016)
3. Terminology
3.1 Definitions:
3.1.1 absorbance, n—logarithm to the base 10 of the ratio of the reciprocal of the transmittance.
3.1.2 atomic absorption spectrometry, n—analytical technique for measuring metal content of solutions, based on a combination
of flame source, hollow cathode lamp, photomultiplier, and a readout device.
3.1.3 atomizer, n—usually a flame source used to decompose the chemical constituents in a solution to its elemental
components.
3.1.4 blank, n—solution which is similar in composition and contents to the sample solution but does not contain the analyte
being measured.
3.1.5 burner, n—flame device used to atomize the analyte by burning in a high temperature flame mixed of a fuel and an oxidant.
3.1.6 calibration, n—process by which the relationship between signal intensity and elemental concentration is determined for
a specific element analysis.
3.1.7 calibration curve, n—plot of signal intensity versus elemental concentration using data obtained by making measurements
with standards.
3.1.8 calibration standard, n—material with a certified value for a relevant property, issued by or traceable to a national
organization such as NIST, and whose properties are known with sufficient accuracy to permit its use to evaluate the same property
of another sample.
3.1.9 certified reference material, n—reference material one or more of whose property values are certified by a technically valid
procedure, accompanied by a traceable certificate or other documentation which is issued by a certifying body.
3.1.10 check standard, n—material having an assigned (known) value (reference value) used to determine the accuracy of the
measurement system or instrument.
3.1.10.1 Discussion—
This practice is not used to calibrate the measurement instrument or system.
3.1.11 detection limit, n—concentration of an analyte that results in a signal intensity that is some multiple (typically two) times
the standard deviation of the background intensity at the measurement wavelength.
3.1.12 dilution factor, n—ratio of sample weight of the aliquot taken to the final diluted volume of its solution.
3.1.12.1 Discussion—
The dilution factor is used to multiply the observed reading and obtain the actual concentration of the analyte in the original
sample.
3.1.13 graphite furnace, n—electrothermal device for atomizing the metal constituents.
3.1.14 hollow cathode lamp, n—device consisting of a quartz envelope containing a cathode of the metal to be determined and
a suitable anode.
3.1.15 hydride generation, n—device to atomize some metals which form gaseous hydrides.
3.1.16 monochromator, n—device that isolates a single atomic resonance line from the line spectrum emitted by the hollow
cathode lamp, excluding all other wavelengths.
3.1.17 nebulizer, n—device that generates an aerosol by flowing a liquid over a surface that contains an orifice from which gas
flows at a high velocity.
3.1.18 NIST, n—National Institute of Standards and Technology, Gaithersburg, MD. Formerly known as National Bureau of
Standards.
3.1.19 precision, n—closeness of agreement between test results obtained under prescribed conditions.
3.1.20 quality assurance, n—system of activities, the purpose of which is to provide to the producer and user of a product,
measurement, or service the assurance that it meets the defined standards of quality with a stated level of confidence.
3.1.21 quality control, n—planned system of activities whose purpose is to provide a level of quality that meets the needs of
users; also the uses of such a system.
3.1.22 quality control sample, n—for use in quality assurance program to determine and monitor the precision and stability of
a measurement system; a stable and homogenous material having physical or chemical properties, or both, similar to those of
typical samples tested by the analytical measurement system.
D7740 − 11 (2016)
3.1.22.1 Discussion—
This material should be properly stored to ensure sample integrity, and is available in sufficient quantity for repeated long term
testing.
3.1.23 reference material, n—material with accepted reference value(s), accompanied by an uncertainty at a stated level of
confidence for desired properties, which may be used for calibration or quality control purposes in the laboratory.
3.1.24 refractory elements, n—elements forming difficult-to-dissociate oxides during combustion.
3.1.25 repeatability, n—difference between two test results, obtained by the same operator with the same apparatus under
constant operating conditions on identical test material would, in the long term and correct operation of the test method, exceed
the values given only in one case in twenty.
3.1.26 reproducibility, n—difference between two single and independent results, obtained by different operators working in
different laboratories on identical test materials, would in the long run, in the normal and correct operation of the test method,
exceed the values given only one case in twenty.
3.1.27 spectrometer, n—instrument used to measure the emission or absorption spectrum emitted by a species in the vaporized
sample.
3.1.28 spectrum, n—array of the components of an emission or absorption arranged in the order of some varying characteristics
such as wavelength, mass, or energy.
3.1.29 standard reference material, n—trademark for reference materials certified by NIST.
4. Summary of Practice
4.1 An Atomic Absorption Spectrometer (AAS) is used to determine the metal composition of various liquid matrices. Although
usually AAS is done using a flame to atomize the metals, graphite furnace (GF-AAS) or cold vapor (CV-AAS) may also be used
for metals at very low levels of concentration or some elements not amenable to flame atomization. This practice summarizes the
protocols to be followed during calibration and verification of the instrument performance.
5. Significance and Use
5.1 Accurate elemental analysis of petroleum products and lubricants is necessary for the determination of chemical properties,
which are used to establish compliance with commercial and regulatory specifications.
5.2 Atomic Absorption Spectrometry (AAS) is one of the most widely used analytical techniques in the oil industry for
elemental analysis. There are at least twelve Standard Test Methods published by ASTM D02 Committee on Petroleum Products
and Lubricants for such analysis. See Table 1.
5.3 The advantage of using an AAS analysis include good sensitivity for most metals, relative freedom from interferences, and
ability to calibrate the instrument based on elemental standards irrespective of their elemental chemical forms. Thus, the technique
has been a method of choice in most of the oil industry laboratories. In many laboratories, AAS has been superseded by a superior
ICP-AES technique (see Practice D7260).
5.4 Some of the ASTM AAS Standard Test Methods have also been issued by other standard writing bodies as technically
equivalent standards. See Table 2.
6. Interferences
6.1 Although over 70 elements can be determined by AAS usually with a precision of 1-3 % and with detection limits of the
order of sub-mg/kg levels, and with little or no atomic spectral interference. However, there are several types of interferences
TABLE 1 Applications of AAS for Metal Analysis of Petroleum Products and Lubricants
ASTM Test Method Matrix Elements Determined
D1318 Residual Fuel Oil Sodium
D3237 Gasoline Lead
D3340 Greases Lithium and Sodium
D3605 Gas Turbine Fuels Calcium, Lead, Sodium, and Vanadium
D3831 Gasoline Manganese
D4628 Automotive Lubricants Barium, Calcium, Magnesium, and Zinc
D5056 Petroleum Coke Aluminum, Calcium, Iron, Nickel, Silicon, Sodium, and Vanadium
D5184 Fuel Oils Aluminum and Silicon
D5863 Crude and Fuel Oils Iron, Nickel, Sodium, and Vanadium
D6732 Jet Fuels Copper
D7622 Crude Oils Mercury
D7623 Crude Oils Mercury
D7740 − 11 (2016)
A
TABLE 2 Equivalent AAS Test Methods
Analysis ASTM Standard EI Standard ISO Standard DIN Standard
Lead in Gasoline D3237 IP 428 8691
Analysis of Gas Turbine Fuels D3605 IP 413 51-790T3
Additive Elements in Lube Oils D4628 IP 308 51-391T1
Al and Si in Fuel Oils D5184 IP 377 10478 51-416
A
Excerpted from ASTM MNL44, Guide to ASTM Test Methods for the Analysis of Petroleum Products and Lubricants, 2nd edition, Ed., Nadkarni, R. A. Kishore, ASTM
International, West Conshohocken, PA, 2007.
possible: chemical, ionization, matrix, emission, spectral, and background absorption interferences. Since these interferences are
well-defined, it is easy to eliminate or compensate for them. See Table 3.
6.1.1 Chemical Interferences—If the sample for analysis contains a thermally stable compound with the analyte that is not
totally decomposed by the energy of the flame, a chemical interference exists. They can normally be overcome or controlled by
using a higher temperature flame or addition of a releasing agent to the sample and standard solutions.
6.1.2 Ionization Interferences—When the flame has enough energy to cause the removal of an electron from the atom, creating
an ion, ionization interference can occur. They can be controlled by addition of an excess of an easily ionized element to both
samples and standards. Normally alkali metals which have very low ionization potentials are used.
6.1.3 Matrix Interferences—These can cause either a suppression or enhancement of the analyte signal. Matrix interferences
occur when the physical characteristics – viscosity, burning characteristics, surface tension – of the sample and standard differ
considerably. To compensate for the matrix interferences, the matrix components in the sample and standard should be matched
as closely as possible. Matrix interferences can also be controlled by diluting the sample solution until the effect of dissolved salts
or acids is negligible. Sometimes, the method of standard addition is used to overcome this interference. See 6.2.
6.1.4 Emission Interferences—At high analyte concentrations, the atomic absorptio
...
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