ASTM D6732-04(2015)
(Test Method)Standard Test Method for Determination of Copper in Jet Fuels by Graphite Furnace Atomic Absorption Spectrometry
Standard Test Method for Determination of Copper in Jet Fuels by Graphite Furnace Atomic Absorption Spectrometry
SIGNIFICANCE AND USE
5.1 At high temperatures aviation turbine fuels can oxidize and produce insoluble deposits that are detrimental to aircraft propulsion systems. Very low copper concentrations (in excess of 50 μg/kg) can significantly accelerate this thermal instability of aviation turbine fuel. Naval shipboard aviation fuel delivery systems contain copper-nickel piping, which can increase copper levels in the fuel. This test method may be used for quality checks of copper levels in aviation fuel samples taken on shipboard, in refineries, and at fuel storage depots.
SCOPE
1.1 This test method covers the determination of copper in jet fuels in the range of 5 μg/kg to 100 μg/kg using graphite furnace atomic absorption spectrometry. Copper contents above 100 μg/kg may be determined by sample dilution with kerosine to bring the copper level into the aforementioned method range. When sample dilution is used, the precision statements do not apply.
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: D6732 − 04 (Reapproved 2015)
Standard Test Method for
Determination of Copper in Jet Fuels by Graphite Furnace
Atomic Absorption Spectrometry
This standard is issued under the fixed designation D6732; 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 3.1.2 transmittance, T, n—the ratio of the radiant power
transmitted by a material to the radiant power incident upon it.
1.1 This test method covers the determination of copper in
jet fuels in the range of 5 µg⁄kg to 100 µg⁄kg using graphite 3.2 Definitions of Terms Specific to This Standard:
furnace atomic absorption spectrometry. Copper contents 3.2.1 absorbance, A, n—the logarithm to the base 10 of the
above 100 µg⁄kg may be determined by sample dilution with ratio of the reciprocal of the transmittance, T:
kerosine to bring the copper level into the aforementioned
A 5 log 1/T 52log T (1)
~ !
10 10
method range. When sample dilution is used, the precision
3.2.2 integrated absorbance, A,n—the integrated area un-
i
statements do not apply.
der the absorbance peak generated by the atomic absorption
1.2 The values stated in SI units are to be regarded as
spectrometer.
standard. No other units of measurement are included in this
standard.
4. Summary of Test Method
1.3 This standard does not purport to address all of the
4.1 The graphite furnace is aligned in the light path of the
safety concerns, if any, associated with its use. It is the
atomic absorption spectrometer equipped with background
responsibility of the user of this standard to establish appro-
correction. An aliquot (typically 10 µL) of the sample is
priate safety and health practices and determine the applica-
pipetted onto a platform in the furnace. The furnace is heated
bility of regulatory limitations prior to use.
to low temperature to dry the sample completely without
spattering. The furnace is then heated to a moderate tempera-
2. Referenced Documents
ture to eliminate excess sample matrix. The furnace is further
heated very rapidly to a temperature high enough to volatilize
2.1 ASTM Standards:
the analyte of interest. It is during this step that the amount of
D4057 Practice for Manual Sampling of Petroleum and
light absorbed by the copper atoms is measured by the
Petroleum Products
spectrometer.
D4306 Practice for Aviation Fuel Sample Containers for
Tests Affected by Trace Contamination
4.2 The light absorbed is measured over a specified period.
D6299 Practice for Applying Statistical Quality Assurance
The integrated absorbance A produced by the copper in the
i
and Control Charting Techniques to Evaluate Analytical
samples is compared to a calibration curve constructed from
Measurement System Performance
measured A values for organo-metallic standards.
i
3. Terminology 5. Significance and Use
3.1 Definitions:
5.1 At high temperatures aviation turbine fuels can oxidize
3.1.1 radiant power, P, n—the rate at which energy is
and produce insoluble deposits that are detrimental to aircraft
transported in a beam of radiant energy.
propulsion systems. Very low copper concentrations (in excess
of 50 µg⁄kg) can significantly accelerate this thermal instabil-
ity of aviation turbine fuel. Naval shipboard aviation fuel
1 delivery systems contain copper-nickel piping, which can
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of
increasecopperlevelsinthefuel.Thistestmethodmaybeused
Subcommittee D02.03 on Elemental Analysis.
for quality checks of copper levels in aviation fuel samples
Current edition approved April 1, 2015. Published May 2015. Originally
taken on shipboard, in refineries, and at fuel storage depots.
approved in 2001. Last previous edition approved in 2010 as D6732 – 04 (2010).
DOI: 10.1520/D6732-04R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 6. Interferences
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
6.1 Interferences most commonly occur due to light that is
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. absorbed by species other than the atomic species of interest.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6732 − 04 (2015)
Generally, this is due to undissociated molecular particles from 9. Sampling
thesamplematrix.Thecharstepinthefurnaceprogramisused
9.1 Samples shall be taken in accordance with procedures
to eliminate as much of the matrix as possible before the
described in Practice D4057.
atomization step. Spectrometers are equipped with background
9.2 Samples shall be thoroughly mixed in their containers
correction capabilities to control further possibilities of erro-
immediately prior to testing.
neous results due to molecular absorption.
10. Calibration and Standardization
7. Apparatus
10.1 Preparation of Standards:
7.1 AtomicAbsorptionSpectrometer—Anatomicabsorption
10.1.1 Nominal 1 mg⁄kg Intermediate Stock Standard—
spectrometer with the capability of setting the wavelength at
Accurately weigh a nominal 0.50 g of the 100 mg⁄kg stock
324.8 nm, setting the slit width at typically 0.7 nm, and using
organo-metallic standard into a suitable container (capable of
peak area integration for the atomic and background readings
being sealed for mixing). (All masses are measured to the
shall be used. The spectrometer shall be equipped with the
nearest 0.0001 g.) Suitable sample containers are described in
following:
Practice D4306. Add enough odorless kerosine to bring the
7.1.1 Copper Hollow Cathode Lamp—as the elemental light
total mass to a nominal 50.00 g. Seal the container and mix
source.
well. See 12.1.1 for calculation of actual concentration.
7.1.2 Background Correction Capability—to cover the
10.1.2 Working Standards of Nominally (20, 40, 60, 80,
324.8 nm wavelength range.
100) µg⁄kg—Accurately weigh a nominal (0.20, 0.40, 0.60,
7.1.3 Graphite Furnace Atomizer—which uses pyrolytically
0.80, 1.00) g of the nominal 1 mg⁄kg intermediate stock
coated graphite tubes with L’vovplatforms.
standardintofivesuitablecontainers.(Allmassesaremeasured
7.2 Autosampler or Manual Pipettor—capable of reproduc- to the nearest 0.0001 g.)Add enough odorless kerosine to each
ibly delivering 10 µL 6 0.5 µL aliquots of samples, standards, container to bring the total mass to a nominal 10.00 g. Seal
containers and mix well. This produces working standards of
and blank to the graphite furnace.
nominal (20, 40, 60, 80, 100) µg⁄kg, respectively. See 12.1.2
7.3 Analytical Balance—capable of weighing 100 g 6
for calculations of actual concentrations.
0.0001 g.
10.2 Calibration:
8. Reagents and Materials
10.2.1 Prepare a standard calibration curve by using the
odorless kerosine as a blank and each of the five working
8.1 Purity of Reagents—Reagent grade chemicals shall be
standards. The instrument measures the integrated absorbance
used in all tests. Unless otherwise indicated, it is intended that
A of 10 µL of each working standard and blank. The interme-
i
all reagents conform to the specifications of the Committee on
diate stock standard and working standards shall be prepared
Analytical Reagents of the American Chemical Society where
daily.
such specifications are available. Other grades may be used,
10.2.2 The calibration curve is constructed by plotting the
provided it is first ascertained that the reagent is of sufficiently
corrected integrated absorbances (on y-axis) versus the con-
high purity to permit its use without lessening the accuracy of
centrations of copper in the working standards in µg/kg (on
the determination.
x-axis). See 12.2.1 for calculating corrected integrated absor-
8.2 Odorless or Low Odor Kerosine, filtered through silica
bance. Fig. 1 shows a typical calibration curve for atomic
gel.
absorption spectroscopy. Many atomic absorption spectrom-
8.3 100 mg/kg Organo-metallic Standard for Copper, or a eters have the capability of constructing the calibration curve
multielement standard containing copper at 100 mg⁄kg.
internally or by way of computer software. Construct the best
possible fit of the data with available means.
8.4 Silica Gel, 100 mesh to 200 mesh.
11. Procedure
8.5 Argon Gas, 99.999 %, (Warning—Argon is a com-
pressed gas under high pressure) for graphite furnace gas flow
11.1 Set the spectrometer at a wavelength of 324.8 nm and
system.
a slit width of typically 0.7 nm.Align the hollow cathode lamp
and furnace assembly to obtain maximum transmittance.
8.6 Quality Control (QC) Samples, preferably are portions
of one or more kerosine materials that are stable and represen-
11.2 Condition new (or reinstalled) graphite tube and L’vov
tativeofthesamplesofinterest.TheseQCsamplescanbeused
platform with the temperature program provided by the spec-
to check the validity of the testing process as described in
trometer manufacturer until the baseline shows no peaks.
Section 14. Use a stable QC concentrate, and dilute it on the
11.3 Calibrate the graphite furnace temperature controller at
day of the QC check to the trace level required.
2300°C according to the spectrometer manufacturer’s instruc-
tions.
11.4 Whenanautosamplerisusedwiththegraphitefurnace,
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
use odorless kerosine as the rinse solution. Use only autosam-
list
...
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: D6732 − 04 (Reapproved 2010) D6732 − 04 (Reapproved 2015)
Standard Test Method for
Determination of Copper in Jet Fuels by Graphite Furnace
Atomic Absorption Spectrometry
This standard is issued under the fixed designation D6732; 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 test method covers the determination of copper in jet fuels in the range of 55 μg ⁄kg to 100100 μg ⁄ μg/kg kg using
graphite furnace atomic absorption spectrometry. Copper contents above 100100 μg ⁄ μg/kg kg may be determined by sample
dilution with kerosine to bring the copper level into the aforementioned method range. When sample dilution is used, the precision
statements do not apply.
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:
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4306 Practice for Aviation Fuel Sample Containers for Tests Affected by Trace Contamination
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
3. Terminology
3.1 Definitions:
3.1.1 radiant power, P, n—the rate at which energy is transported in a beam of radiant energy.
3.1.2 transmittance, T, n—the ratio of the radiant power transmitted by a material to the radiant power incident upon it.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 absorbance, A, n—the logarithm to the base 10 of the ratio of the reciprocal of the transmittance, T:
A 5 log ~1/T! 52log T (1)
10 10
3.2.2 integrated absorbance, A , n—the integrated area under the absorbance peak generated by the atomic absorption
i
spectrometer.
4. Summary of Test Method
4.1 The graphite furnace is aligned in the light path of the atomic absorption spectrometer equipped with background correction.
An aliquot (typically 10 μL) 10 μL) of the sample is pipetted onto a platform in the furnace. The furnace is heated to low
temperature to dry the sample completely without spattering. The furnace is then heated to a moderate temperature to eliminate
excess sample matrix. The furnace is further heated very rapidly to a temperature high enough to volatilize the analyte of interest.
It is during this step that the amount of light absorbed by the copper atoms is measured by the spectrometer.
4.2 The light absorbed is measured over a specified period. The integrated absorbance A produced by the copper in the samples
i
is compared to a calibration curve constructed from measured A values for organo-metallic standards.
i
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products Products, Liquid Fuels, and Lubricantsand is the direct responsibility of
Subcommittee D02.03 on Elemental Analysis.
Current edition approved May 1, 2010April 1, 2015. Published May 2010May 2015. Originally approved in 2001. Last previous edition approved in 20042010 as
D6732D6732 – 04 (2010).–04. DOI: 10.1520/D6732-04R10.10.1520/D6732-04R15.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6732 − 04 (2015)
5. Significance and Use
5.1 At high temperatures aviation turbine fuels can oxidize and produce insoluble deposits that are detrimental to aircraft
propulsion systems. Very low copper concentrations (in excess of 5050 μg ⁄ μg/kg) kg) can significantly accelerate this thermal
instability of aviation turbine fuel. Naval shipboard aviation fuel delivery systems contain copper-nickel piping, which can increase
copper levels in the fuel. This test method may be used for quality checks of copper levels in aviation fuel samples taken on
shipboard, in refineries, and at fuel storage depots.
6. Interferences
6.1 Interferences most commonly occur due to light that is absorbed by species other than the atomic species of interest.
Generally, this is due to undissociated molecular particles from the sample matrix. The char step in the furnace program is used
to eliminate as much of the matrix as possible before the atomization step. Spectrometers are equipped with background correction
capabilities to control further possibilities of erroneous results due to molecular absorption.
7. Apparatus
7.1 Atomic Absorption Spectrometer—An atomic absorption spectrometer with the capability of setting the wavelength at 324.8
nm, 324.8 nm, setting the slit width at typically 0.7 nm, 0.7 nm, and using peak area integration for the atomic and background
readings shall be used. The spectrometer shall be equipped with the following:
7.1.1 Copper Hollow Cathode Lamp—as the elemental light source.
7.1.2 Background Correction Capability—to cover the 324.8 nm 324.8 nm wavelength range.
7.1.3 Graphite Furnace Atomizer—which uses pyrolytically coated graphite tubes with L’vovplatforms.
7.2 Autosampler or Manual Pipettor—capable of reproducibly delivering 1010 μL 6 0.5 μL 0.5 μL aliquots of samples,
standards, and blank to the graphite furnace.
7.3 Analytical Balance—capable of weighing 100 g 6 0.0001 g.100 g 6 0.0001 g.
8. Reagents and Materials
8.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such
specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity
to permit its use without lessening the accuracy of the determination.
8.2 Odorless or Low Odor Kerosine, filtered through silica gel.
8.3 100 mg/kg Organo-metallic Standard for Copper, or a multielement standard containing copper at 100 100 mg mg/kg.⁄kg.
8.4 Silica Gel, 100100 mesh to 200 mesh.200 mesh.
8.5 Argon Gas, 99.999%,99.999 %, (Warning—Argon is a compressed gas under high pressure) for graphite furnace gas flow
system.
8.6 Quality Control (QC) Samples, preferably are portions of one or more kerosine materials that are stable and representative
of the samples of interest. These QC samples can be used to check the validity of the testing process as described in Section 14.
Use a stable QC concentrate, and dilute it on the day of the QC check to the trace level required.
9. Sampling
9.1 Samples shall be taken in accordance with procedures described in Practice D4057.
9.2 Samples shall be thoroughly mixed in their containers immediately prior to testing.
10. Calibration and Standardization
10.1 Preparation of Standards:
10.1.1 Nominal 11 mg ⁄ mg/kg kg Intermediate Stock Standard—Accurately weigh a nominal 0.50 g 0.50 g of the 100100 mg ⁄
mg/kg kg stock organo-metallic standard into a suitable container (capable of being sealed for mixing). (All masses are measured
to the nearest 0.0001 g.) 0.0001 g.) Suitable sample containers are described in Practice D4306. Add enough odorless kerosine to
bring the total mass to a nominal 50.00 g. 50.00 g. Seal the container and mix well. See 12.1.1 for calculation of actual
concentration.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
D6732 − 04 (2015)
FIG. 1 Typical Calibration Curve of Copper Concentration versus Integrated Absorbance (A )
i
10.1.2 Working Standards of Nominally 20,(20, 40, 60, 80, and 100) μg 100 ⁄μg/kg—kg—Accurately weigh a nominal
0.20,(0.20, 0.40, 0.60, 0.80, and 1.00 g 1.00) g of the nominal 11 mg ⁄ mg/kg kg intermediate stock standard into five suitable
containers. (All masses are measured to the nearest 0.0001 g.) 0.0001 g.) Add enough odorless kerosine to each container to bring
the total mass to a nominal 10.00 g. 10.00 g. Seal containers and mix well. This produces working standards of nominal 20,(20,
40, 60, 80, and100) μg ⁄ 100 μg/kg, kg, respectively. See 12.1.2 for calculations of actual concentrations.
10.2 Calibration:
10.2.1 Prepare a standard calibration curve by using the odorless kerosine as a blank and each of the five working standards.
The instrument measures the integrated absorbance A of 10 μL 10 μL of each working standard and blank. The intermediate stock
i
standard and working standards shall be prepared daily.
10.2.2 The calibration curve is constructed by plotting the corrected integrated absorbances (on y-axis)y-axis) versus the
concentrations of copper in the working standards in μg/kg (on x-axis).x-axis). See 12.2.1 for calculating corrected integrated
absorbance. Fig. 1 shows a typical calibration curve for atomic absorption spectroscopy. Many atomic absorption spectrometers
have the capability of constructing the calibration curve internally or by way of computer software. Construct the best possible fit
of the data with available means.
11. Procedure
11.1 Set the spec
...
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