ASTM D6756-10(2015)
(Test Method)Standard Test Method for Determination of the Red Dye Concentration and Estimation of the ASTM Color of Diesel Fuel and Heating Oil Using a Portable Visible Spectrophotometer
Standard Test Method for Determination of the Red Dye Concentration and Estimation of the ASTM Color of Diesel Fuel and Heating Oil Using a Portable Visible Spectrophotometer
SIGNIFICANCE AND USE
5.1 In the United States, high sulfur content (defined by the United States Environmental Protection Agency (USEPA)) middle distillate products and diesel fuel used for off-road purposes, other than aviation turbine fuel, are required by government agencies to contain red dye. The dye concentration required to be present in high sulfur and off-road diesel products is regulated by the United States Environmental Protection Agency and the United States Internal Revenue Service, respectively.
5.2 Some fuels that are readily exchanged in the market have a color specification. The color of the base fuel is masked by the presence of the red dye. This test method provides a means of estimating the base color of Number 1 and Number 2 diesel fuel and heating oil in the presence of red dye.
5.3 The test method provides a means to indicate conformance to contractual and legal requirements.
SCOPE
1.1 This test method covers the determination of the red dye concentration of diesel fuel and heating oil and the estimation of the ASTM color of undyed and red-dyed diesel fuel and heating oil. The test method is appropriate for use with diesel fuel and heating oil of Grades 1 and 2 described in Specifications D396, D975, D2880 and D3699. Red dye concentrations are determined at levels equivalent to 0.1 mg/L to 20 mg/L of Solvent Red 26 in samples with ASTM colors ranging from 0.5 to 5. The ASTM color of the base fuel of red-dyed samples with concentration levels equivalent to 0.1 mg/L to 20 mg/L of Solvent Red 26 is estimated for the ASTM color range from 0.5 to 5. The ASTM color of undyed samples is estimated over the ASTM color range of 0.5 to 5.
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: D6756 − 10 (Reapproved 2015)
Standard Test Method for
Determination of the Red Dye Concentration and Estimation
of the ASTM Color of Diesel Fuel and Heating Oil Using a
Portable Visible Spectrophotometer
This standard is issued under the fixed designation D6756; 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 D4052Test Method for Density, Relative Density, and API
Gravity of Liquids by Digital Density Meter
1.1 Thistestmethodcoversthedeterminationofthereddye
D4057Practice for Manual Sampling of Petroleum and
concentration of diesel fuel and heating oil and the estimation
Petroleum Products
of the ASTM color of undyed and red-dyed diesel fuel and
D4177Practice for Automatic Sampling of Petroleum and
heating oil. The test method is appropriate for use with diesel
Petroleum Products
fuel and heating oil of Grades 1 and 2 described in Specifica-
D6045Test Method for Color of Petroleum Products by the
tions D396, D975, D2880 and D3699. Red dye concentrations
Automatic Tristimulus Method
are determined at levels equivalent to 0.1mg⁄Lto 20mg⁄Lof
D6708Practice for StatisticalAssessment and Improvement
SolventRed26insampleswithASTMcolorsrangingfrom0.5
of Expected Agreement Between Two Test Methods that
to 5. The ASTM color of the base fuel of red-dyed samples
Purport to Measure the Same Property of a Material
with concentration levels equivalent to 0.1mg⁄L to 20mg⁄L
E203Test Method for Water Using Volumetric Karl Fischer
ofSolventRed26isestimatedfortheASTMcolorrangefrom
Titration
0.5to5.TheASTMcolorofundyedsamplesisestimatedover
E1655 Practices for Infrared Multivariate Quantitative
the ASTM color range of 0.5 to 5.
Analysis
1.2 The values stated in SI units are to be regarded as
E2056Practice for Qualifying Spectrometers and Spectro-
standard. No other units of measurement are included in this
photometers for Use in MultivariateAnalyses, Calibrated
standard.
Using Surrogate Mixtures
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions:
priate safety and health practices and determine the applica-
3.1.1 ASTM color, n—the name of an empirical scale of
bility of regulatory limitations prior to use.
expressing the color of a petroleum liquid darker than Saybolt
2. Referenced Documents color based on a scale of 0.5 (lightest) to 8 Dil (darkest) and
determined by Test Method D1500.
2.1 ASTM Standards:
D396Specification for Fuel Oils
3.1.2 surrogate calibration, n—a multivariate calibration
D975Specification for Diesel Fuel Oils
that is developed using a calibration set which consists of
D1500Test Method forASTM Color of Petroleum Products
mixtureswithpre-specifiedandreproduciblecompositionsthat
(ASTM Color Scale)
contain substantially fewer chemical components than the
D2880Specification for Gas Turbine Fuel Oils
samples which will ultimately be analyzed. E2056
D3699Specification for Kerosine
3.1.3 surrogate method, n—a standard test method that is
based on a surrogate calibration. E2056
This test method is under the jurisdiction of ASTM Committee D02 on
3.2 Definitions of Terms Specific to This Standard:
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
SubcommitteeD02.05onPropertiesofFuels,PetroleumCokeandCarbonMaterial.
3.2.1 red dye, n—substance that, when added to fuel,
Current edition approved Oct. 1, 2015. Published December 2015. Originally
absorbs green light and imparts a red color to the product. For
approved in 2002. Last previous edition approved in 2010 as D6756–10. DOI:
this test method, red dyes are:
10.1520/D6756-10R15.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.1.1 product dyes, n—alkyl derivatives of azobenzene-4-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
azo-2-naphthol (methyl derivatives of Color Index No. 26105)
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. which are more soluble in diesel fuel.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6756 − 10 (2015)
3.2.1.2 solvent red 26, n—an azobenzene-4-azo-2-naphthol more than one cell is used for calibration, qualification and
dye of a specific chemical structure that is used to gage the sample measurement, the path length of the cells must be
amount of red dye present in a given sample. matched to 60.001cm.
4. Summary of Test Method
8. Sampling
4.1 A sample is introduced into the liquid specimen cell.
8.1 Samples shall be taken in accordance with Practice
The cell is placed into the light path of the apparatus.Abeam
D4057 or D4177.
of visible light is imaged through the sample onto a detector,
8.2 Precautions must be taken to shield the samples from
and the detector response is determined. Wavelengths of the
light prior to analysis.
spectrum, which correlate highly with the red dye concentra-
tion and the ASTM color, are selected for analysis using
9. Calibration and Standardization of the Apparatus
selective bandpass filters. A multivariate mathematical model
9.1 The instrument is calibrated according to the procedure
converts the absorption values from the filters to the red dye
described in Annex A2.
concentration and the estimated ASTM color.
NOTE 1—The DT100C instruments are calibrated at the factory by the
vendor.
5. Significance and Use
9.2 The instrument is qualified according to the procedure
5.1 In the United States, high sulfur content (defined by the
described in Annex A3.
United States Environmental Protection Agency (USEPA))
middle distillate products and diesel fuel used for off-road NOTE 2—The DT100C instruments are qualified at the factory by the
vendor.
purposes, other than aviation turbine fuel, are required by
governmentagenciestocontainreddye.Thedyeconcentration
9.2.1 If the qualification procedure is performed by the
required to be present in high sulfur and off-road diesel vendor, then the user shall perform a quality control check
products is regulated by the United States Environmental
according to the procedure described in Section 10.
Protection Agency and the United States Internal Revenue
10. Quality Control Check
Service, respectively.
10.1 Toconfirmtheperformanceoftheinstrument,periodi-
5.2 Some fuels that are readily exchanged in the market
callymeasurethereddyeconcentrationandtheASTMcolorof
haveacolorspecification.Thecolorofthebasefuelismasked
three control samples using the procedure outlined in Section
by the presence of the red dye. This test method provides a
11. The quality control check standards should be analyzed at
means of estimating the base color of Number 1 and Number
least once a week or before the sample analysis if the
2 diesel fuel and heating oil in the presence of red dye.
instrument is used less frequently than weekly or if the
5.3 The test method provides a means to indicate confor-
instrument is moved to a different laboratory or field location.
mance to contractual and legal requirements.
NOTE 3—Quality control samples are available from DT100C .
6. Interferences
10.1.1 A standard of known dye concentration and ASTM
6.1 The presence of colorants other than the hydrocarbons
color is made according to the information in A1.4. The set of
typical of Number 1 and 2 diesel fuel and heating oils, or the
qualitycontrolsamplesshallhavealow,medium,andhighred
presenceofreddyeotherthanthespecifiedtypes,caninterfere
dye concentration (0mg⁄L to 14mg⁄L 6 2mg⁄L) and a low,
with the accurate determination of the red dye concentration
medium, and high ASTM color (0 to 5 ASTM color units).
reported as Solvent Red 26 equivalent or the base fuelASTM
10.1.2 The standards are stable for at least one year when
color.
stored in the dark in tightly sealed bottles.
10.2 If the red dye concentration determined for one of the
7. Apparatus
quality control samples differs from the known value by more
7.1 Filter Spectrophotometer, is equipped with specimen
than 1.0mg⁄L or if the estimated ASTM color for one of the
chamber, visible wavelength source, four 10nm 6 2nm (full
quality control samples differs from the known value by more
width at half transmission maximum) bandpass wavelength
than 0.5 units, then the measurement system is out-of-control
discriminating filters having center wavelengths at 450nm 6
and cannot be used to determine the red dye concentration or
2nm, 520nm 6 2nm, 650nm 6 2nm, and 700nm 6 2nm.
used to estimate the ASTM color until the cause of the
The bandpass filters are used in conjunction with the visible
out-of-control behavior is corrected.
wavelength source to produce light in the blue, green, red, and
10.3 If correction of out-of-control behavior requires repair
far-red regions of the electromagnetic spectrum. A detector
to the instrument or recalibration of the instrument, the
converts the transmitted light to an electronic signal that is
3,4
qualificationofinstrumentperformancedescribedinAnnexA3
processed by an A-D converter and a microprocessor.
7.2 Specimen Cell, constructed of polymethacrylate or clear
optical glass having a path length of approximately 1cm. If
Thesolesourceofsupplyoftheapparatusknowntothecommitteeatthistime
is PetroSpec, Inc. If you are aware of alternative suppliers, please provide this
information to ASTM International Headquarters. Your comments will receive
3 1
DT100C instruments used to develop this precision statement are available careful consideration at a meeting of the responsible technical committee, which
from PetroSpec, Inc., 530 Main St., Acton, MA 01720. you may attend.
D6756 − 10 (2015)
shall be performed before the system is used to measure red r 50.085ASTMcolorunits
dye concentration or used to estimate ASTM color.
for samples in the ASTM color range of 0 to 5.
13.1.2 Reproducibility—The difference between two single
11. Procedure
andindependentresultsobtainedfromdifferentinstrumentson
11.1 Prepare the filter spectrophotometer for operation in
identicalsamples,wouldinthelongrun,innormalandcorrect
accordance with the manufacturer’s instructions.
operation of the test method, exceed the following value in
11.2 Equilibrate the sample to between 20°C and 25°C.
only one case in twenty:
11.3 Without filtering the sample (see 13.6), fill a clean, dry R 50.86mg/L
specimen cell. The external optical surfaces shall be clean. If
for Solvent Red 26 equivalent dye concentrations between
not, wipe clean and dry with a piece of lint-free paper (for
0.1mg⁄L and 20.0mg⁄L, and
example, lens paper).
R 5 0.20 ASTMcolorunits
11.4 Insert the specimen cell into the cell chamber of the
instrument.
for samples in the ASTM color range of 0 to 5.
11.5 Record the Solvent Red 26 equivalent concentration
13.2 Bias—Since there is no accepted reference material
and the estimated ASTM color.
suitable for determining the bias for the procedure in this test
method, bias has not been determined.
12. Report
13.3 Relative Bias (Dye Concentration)—Some relative
12.1 Report the red dye concentration to the nearest
bias, among certain samples, was observed when the Solvent
0.1mg⁄L as Solvent Red 26 equivalent dye.
Red 26 concentration results were compared to the expected
NOTE 4—The number of milligrams per litre of Solvent Red 26
Solvent Red 26 concentrations. The bias between the theoreti-
equivalents measured by the DT100C instrument is labeled as ppm on the
cal and measured Solvent Red 26 concentration is observed
display.TheppmunitreportedbytheDT100Cinstrumentisequivalentto
mg/L. with the test samples that were made using Solvent Red 164,
the chemical used to commercially dye diesel fuel. The
12.2 Report the estimated ASTM color value as: estimated
observed bias does appear to be of a systematic nature and is
ASTM color using ASTM D6756. Report the result to the
not known to be related to the accuracy of this test method,
nearest 0.1 color value.
since the Solvent Red 26 equivalency of the Solvent Red 164
12.2.1 The reported estimated ASTM color value can be
used in sample preparation has not been determined, only
converted to a value that mimics the reporting convention of
estimated.
theTestMethodD1500.ForestimatedASTMcolorvaluesthat
are x.0 or x.5, the estimated value is reported unchanged. For
13.4 Relative Bias (ASTM Color)—Relative bias, for one
estimatedcolorvaluesbetweenx.1andx.4,roundupthevalue
sample,wasobservedwhenthecolorresultswerecomparedto
to the nearest x.5 and place an L before the result. For
the Test Method D1500 results; however, this bias is near the
estimatedcolorvaluesbetweenx.6andx.9,roundupthevalue
reproducibility of the test methods and is inconclusive. The
to the nearest whole number and place an L before the result.
overall relative bias to Test Method D1500 is not significant.
If the estimated color value is greater than 8.0, report the
NOTE5—TheaveragebiasoftheestimatedASTMcolorrelativetoTest
estimated result as >8. Method D1500 was −0.17. The largest average biases, −0.4 to −0.5, were
observed for four samples that had an ASTM color of 0.5 and red dye
concentrations that ranged from 10mg⁄L to 20mg⁄L.
13. Precision and Bias
13.5 Relative Bias (Unfiltered vs. Filtered Samples)—A
13.1 Interlaboratory tests of the procedure were carried out
single laboratory analyzed a total of 99 separate split samples
usingsixteensamplescoveringthereddyeconcentrationrange
(unfilteredversusfiltered)todeterminetheimpactthatfiltering
equivalent to 0mg⁄L to 16mg⁄L of Solvent Red 26 equiva-
samples can have on reported red dye concentration results.
lents and covering the range of ASTM color from 0.5 to 3.0.
Based on a Practice D6708 analysis of the results, where the
Sevenlaboratoriesparticipatedintheinterlaboratorytests.The
Y-method was unfiltered samples and the X-method was
precision of this procedure as determined by the statistical
filtered samples, a bias correction formula of Y = X – 0.107
examination of the interlaboratory test results is as follows:
was determined. In short, filtering the samples led to a
13.1.1 Repeatability—The difference between successive
statistically significant bias being determined. As such, to
test results obtained with the same apparatus under constant
ensure testing consistency between laboratories, samples are
operating conditions on identical samples would in the long
not to be filtered as indicated in 11.3. Inclusion of the Test
run,innormalandcorre
...
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: D6756 − 10 D6756 − 10 (Reapproved 2015)
Standard Test Method for
Determination of the Red Dye Concentration and Estimation
of the ASTM Color of Diesel Fuel and Heating Oil Using a
Portable Visible Spectrophotometer
This standard is issued under the fixed designation D6756; 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*Scope
1.1 This test method covers the determination of the red dye concentration of diesel fuel and heating oil and the estimation of
the ASTM color of undyed and red-dyed diesel fuel and heating oil. The test method is appropriate for use with diesel fuel and
heating oil of Grades 1 and 2 described in Specifications D396, D975, D2880 and D3699. Red dye concentrations are determined
at levels equivalent to 0.10.1 mg ⁄L to 2020 mg ⁄ mg/L L of Solvent Red 26 in samples with ASTM colors ranging from 0.5 to 5.
The ASTM color of the base fuel of red-dyed samples with concentration levels equivalent to 0.10.1 mg ⁄L to 2020 mg ⁄ mg/L L
of Solvent Red 26 is estimated for the ASTM color range from 0.5 to 5. The ASTM color of undyed samples is estimated over
the ASTM color range of 0.5 to 5.
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:
D396 Specification for Fuel Oils
D975 Specification for Diesel Fuel Oils
D1500 Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)
D2880 Specification for Gas Turbine Fuel Oils
D3699 Specification for Kerosine
D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6045 Test Method for Color of Petroleum Products by the Automatic Tristimulus Method
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
E203 Test Method for Water Using Volumetric Karl Fischer Titration
E1655 Practices for Infrared Multivariate Quantitative Analysis
E2056 Practice for Qualifying Spectrometers and Spectrophotometers for Use in Multivariate Analyses, Calibrated Using
Surrogate Mixtures
3. Terminology
3.1 Definitions:
3.1.1 ASTM color, n—the name of an empirical scale of expressing the color of a petroleum liquid darker than Saybolt color
based on a scale of 0.5 (lightest) to 8 Dil (darkest) and determined by Test Method D1500.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.
Current edition approved Oct. 1, 2010Oct. 1, 2015. Published November 2010December 2015. Originally approved in 2002. Last previous edition approved in 20092010
as D6756D6756 – 10.–09a. DOI: 10.1520/D6756-10.10.1520/D6756-10R15.
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.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6756 − 10 (2015)
3.1.2 surrogate calibration, n—a multivariate calibration that is developed using a calibration set which consists of mixtures
with pre-specified and reproducible compositions that contain substantially fewer chemical components than the samples which
will ultimately be analyzed. E2056
3.1.3 surrogate method, n—a standard test method that is based on a surrogate calibration. E2056
3.2 Definitions of Terms Specific to This Standard:
3.2.1 red dye, n—substance that, when added to fuel, absorbs green light and imparts a red color to the product. For this test
method, red dyes are:
3.2.1.1 product dyes, n—alkyl derivatives of azobenzene-4-azo-2-naphthol (methyl derivatives of Color Index No. 26105)
which are more soluble in diesel fuel.
3.2.1.2 solvent red 26, n—an azobenzene-4-azo-2-naphthol dye of a specific chemical structure that is used to gage the amount
of red dye present in a given sample.
4. Summary of Test Method
4.1 A sample is introduced into the liquid specimen cell. The cell is placed into the light path of the apparatus. A beam of visible
light is imaged through the sample onto a detector, and the detector response is determined. Wavelengths of the spectrum, which
correlate highly with the red dye concentration and the ASTM color, are selected for analysis using selective bandpass filters. A
multivariate mathematical model converts the absorption values from the filters to the red dye concentration and the estimated
ASTM color.
5. Significance and Use
5.1 In the United States, high sulfur content (defined by the United States Environmental Protection Agency (USEPA)) middle
distillate products and diesel fuel used for off-road purposes, other than aviation turbine fuel, are required by government agencies
to contain red dye. The dye concentration required to be present in high sulfur and off-road diesel products is regulated by the
United States Environmental Protection Agency and the United States Internal Revenue Service, respectively.
5.2 Some fuels that are readily exchanged in the market have a color specification. The color of the base fuel is masked by the
presence of the red dye. This test method provides a means of estimating the base color of Number 1 and Number 2 diesel fuel
and heating oil in the presence of red dye.
5.3 The test method provides a means to indicate conformance to contractual and legal requirements.
6. Interferences
6.1 The presence of colorants other than the hydrocarbons typical of Number 1 and 2 diesel fuel and heating oils, or the presence
of red dye other than the specified types, can interfere with the accurate determination of the red dye concentration reported as
Solvent Red 26 equivalent or the base fuel ASTM color.
7. Apparatus
7.1 Filter Spectrophotometer, is equipped with specimen chamber, visible wavelength source, four 1010 nm 6 2 nm 2 nm (full
width at half transmission maximum) bandpass wavelength discriminating filters having center wavelengths at 450 6 2 nm, 520
6 2 nm, 650 6 2 nm, and 700 6 2 nm. 450 nm 6 2 nm, 520 nm 6 2 nm, 650 nm 6 2 nm, and 700 nm 6 2 nm. The bandpass
filters are used in conjunction with the visible wavelength source to produce light in the blue, green, red, and far-red regions of
the electromagnetic spectrum. A detector converts the transmitted light to an electronic signal that is processed by an A-D converter
3,4
and a microprocessor.
7.2 Specimen Cell, constructed of polymethacrylate or clear optical glass having a path length of approximately 1 cm. 1 cm. If
more than one cell is used for calibration, qualification and sample measurement, the path length of the cells must be matched to
60.001 cm.60.001 cm.
8. Sampling
8.1 Samples shall be taken in accordance with Practice D4057 or D4177.
8.2 Precautions must be taken to shield the samples from light prior to analysis.
9. Calibration and Standardization of the Apparatus
9.1 The instrument is calibrated according to the procedure described in Annex A2.
NOTE 1—The DT100C instruments are calibrated at the factory by the vendor.
DT100C instruments used to develop this precision statement are available from PetroSpec, Inc., 530 Main St., Acton, MA 01720.
The sole source of supply of the apparatus known to the committee at this time is PetroSpec, Inc. If you are aware of alternative suppliers, please provide this information
to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
D6756 − 10 (2015)
9.2 The instrument is qualified according to the procedure described in Annex A3.
NOTE 2—The DT100C instruments are qualified at the factory by the vendor.
9.2.1 If the qualification procedure is performed by the vendor, then the user shall perform a quality control check according
to the procedure described in Section 10.
10. Quality Control Check
10.1 To confirm the performance of the instrument, periodically measure the red dye concentration and the ASTM color of three
control samples using the procedure outlined in Section 11. The quality control check standards should be analyzed at least once
a week or before the sample analysis if the instrument is used less frequently than weekly or if the instrument is moved to a
different laboratory or field location.
NOTE 3—Quality control samples are available from DT100C .
10.1.1 A standard of known dye concentration and ASTM color is made according to the information in A1.4. The set of quality
control samples shall have a low, medium, and high red dye concentration (0(0 mg ⁄L to 1414 mg ⁄L 6 22 mg ⁄ mg/L) L) and a
low, medium, and high ASTM color (0 to 5 ASTM color units).
10.1.2 The standards are stable for at least one year when stored in the dark in tightly sealed bottles.
10.2 If the red dye concentration determined for one of the quality control samples differs from the known value by more than
1.01.0 mg ⁄ mg/L L or if the estimated ASTM color for one of the quality control samples differs from the known value by more
than 0.5 units, then the measurement system is out-of-control and cannot be used to determine the red dye concentration or used
to estimate the ASTM color until the cause of the out-of-control behavior is corrected.
10.3 If correction of out-of-control behavior requires repair to the instrument or recalibration of the instrument, the qualification
of instrument performance described in Annex A3 shall be performed before the system is used to measure red dye concentration
or used to estimate ASTM color.
11. Procedure
11.1 Prepare the filter spectrophotometer for operation in accordance with the manufacturer’s instructions.
11.2 Equilibrate the sample to between 2020 °C and 25°C.25 °C.
11.3 Without filtering the sample (see 13.6), fill a clean, dry specimen cell. The external optical surfaces shall be clean. If not,
wipe clean and dry with a piece of lint-free paper (for example, lens paper).
11.4 Insert the specimen cell into the cell chamber of the instrument.
11.5 Record the Solvent Red 26 equivalent concentration and the estimated ASTM color.
12. Report
12.1 Report the red dye concentration to the nearest 0.10.1 mg ⁄ mg/L L as Solvent Red 26 equivalent dye.
NOTE 4—The number of milligrams per litre of Solvent Red 26 equivalents measured by the DT100C instrument is labeled as ppm on the display. The
ppm unit reported by the DT100C instrument is equivalent to mg/L.
12.2 Report the estimated ASTM color value as: estimated ASTM color using ASTM D6756. Report the result to the nearest 0.1
color value.
12.2.1 The reported estimated ASTM color value can be converted to a value that mimics the reporting convention of the Test
Method D1500. For estimated ASTM color values that are x.0 or x.5, the estimated value is reported unchanged. For estimated
color values between x.1 and x.4, round up the value to the nearest x.5 and place an L before the result. For estimated color values
between x.6 and x.9, round up the value to the nearest whole number and place an L before the result. If the estimated color value
is greater than 8.0, report the estimated result as >8.
13. Precision and Bias
13.1 Interlaboratory tests of the procedure were carried out using sixteen samples covering the red dye concentration range
equivalent to 00 mg ⁄L to 1616 mg ⁄ mg/L L of Solvent Red 26 equivalents and covering the range of ASTM color from 0.5 to 3.0.
Seven laboratories participated in the interlaboratory tests. The precision of this procedure as determined by the statistical
examination of the interlaboratory test results is as follows:
13.1.1 Repeatability—The difference between successive test results obtained with the same apparatus under constant operating
conditions on identical samples would in the long run, in normal and correct operation of the test method, exceed the following
value in only one case in twenty:
r 5 0.22 mg/L
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1521.
D6756 − 10 (2015)
for Solvent Red 26 equivalent dye concentrations between 0.10.1 mg ⁄L and 20.020.0 mg ⁄ mg/L, L, and
r 5 0.085 ASTM color units
for samples in the ASTM color range of 0 to 5.
13.1.2 Reproducibility—The difference between two single and independent results obtained from different instruments on
identical samples, would in the long run, in normal and correct operation of the test method, exceed the following value in only
one case in twenty:
R 5 0.86 mg/L
for Solvent Red 26 equivalent dye concentrations between 0.10.1 mg ⁄L and 20.020.0 mg ⁄ mg/L, L, and
R 50.20 ASTM color units
for samples in the ASTM color range of 0 to 5.
13.2 Bias—Since there is no accepted reference material suitable for determining the bias for the procedure in this test method,
bias has not been determined.
13.3 Relative Bias (Dye Concentration)—Some relative bias, among certain samples, was observed when the Solvent Red 26
concentration results were compared to the expected Solvent Red 26 concentrations. The bias between the theoretical and measured
Solvent Red 26 concentration is observed with the test samples that were made using Solvent Red 164, the chemical used to
commercially dye diesel fuel. The observed bias does appear to be of a systematic nature and is not known to be related to the
accuracy of this test method, since the Solvent Red 26 equivalency of the Solvent Red 164 used in
...
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