ASTM D5501-20

Standard Test Method for Determination of Ethanol and Methanol Content in Fuels Containing Greater than 20 % Ethanol by Gas Chromatography

SIGNIFICANCE AND USE
5.1 This test method provides a method of determining the percentage of ethanol in an ethanol-gasoline fuel blend over the range of 20 % by mass to 100 % by mass for compliance with fuel specifications and federal or local fuel regulations.  
5.2 Ethanol content of denatured fuel ethanol for gasoline blending is required in accordance with Specification D4806.  
5.3 Ethanol content of ethanol fuel blends for flexible-fuel automotive spark-ignition engines is required in accordance with Specification D5798.  
5.4 This test method is acceptable for determining the percentage of ethanol for either denatured fuel ethanol or undenatured ethanol for use in industrial applications using Table 3(a) or Table 3(b).  
5.4.1 Refer to local, federal, or other authorities having jurisdiction for information regarding the correct implementation of either Table 3(a) or Table 3(b).  
5.4.2 Specific regulatory requirements for U.S. domestic fuel applications are given in Appendix X5 for information.
SCOPE
1.1 This test method covers the determination of the ethanol content of hydrocarbon blends containing greater than 20 % ethanol. This method is applicable to denatured fuel ethanol, ethanol fuel blends, and mid-level ethanol blends.  
1.1.1 Ethanol is determined from 20 % by mass to 100 % by mass and methanol is determined from 0.01 % by mass to 0.6 % by mass. Equations used to convert these individual alcohols from percent by mass to percent by volume are provided.
Note 1: Fuels containing less than 20 % ethanol may be quantified using Test Method D5599, and less than 12 % ethanol may be quantified using Test Method D4815.  
1.2 This test method does not purport to identify all individual components common to ethanol production or those components that make up the denaturant or hydrocarbon constituent of the fuel.  
1.3 Water cannot be determined by this test method and shall be measured by a procedure such as Test Method D7923, E203, or E1064 and the result used to correct the concentrations determined by this method.  
1.4 This test method is inappropriate for impurities that boil at temperatures higher than 225 °C or for impurities that cause poor or no response in a flame ionization detector, such as water.  
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.  
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Apr-2020
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0L - Gas Chromatography Methods

Relations

• Refers: ASTM E1064-24 - Standard Test Method for Water in Organic Liquids by Coulometric Karl Fischer Titration
• Effective Date: 01-Jan-2024
• Refers: ASTM E203-24 - Standard Test Method for Water Using Volumetric Karl Fischer Titration
• Effective Date: 01-Jan-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D6299-23a - Standard Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measurement System Performance
• Effective Date: 01-Dec-2023
• Refers: ASTM D6792-23c - Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
• Effective Date: 01-Nov-2023
• Refers: ASTM D6792-23b - Standard Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
• Effective Date: 01-Oct-2023
• Refers: ASTM D4626-23 - Standard Practice for Calculation of Gas Chromatographic Response Factors
• Effective Date: 01-Oct-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D4626-95(2019) - Standard Practice for Calculation of Gas Chromatographic Response Factors
• Effective Date: 01-Dec-2019
• Refers: ASTM D4806-19a - Standard Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel
• Effective Date: 15-Sep-2019
• Refers: ASTM E594-96(2019) - Standard Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
• Effective Date: 01-Sep-2019
• Refers: ASTM D5798-19b - Standard Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines
• Effective Date: 01-Jul-2019
• Refers: ASTM D7923-19 - Standard Test Method for Water in Ethanol and Hydrocarbon Blends by Karl Fischer Titration
• Effective Date: 01-Jun-2019
• Refers: ASTM D5798-19a - Standard Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines
• Effective Date: 01-May-2019
• Refers: ASTM D4806-19 - Standard Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel
• Effective Date: 01-Mar-2019

Overview

ASTM D5501-20: Standard Test Method for Determination of Ethanol and Methanol Content in Fuels Containing Greater than 20% Ethanol by Gas Chromatography establishes procedures for accurately quantifying ethanol and methanol concentrations in hydrocarbon fuel blends that contain more than 20% ethanol by mass. Developed by ASTM, this test method supports compliance with fuel quality standards and regulatory requirements for denatured fuel ethanol, flexible-fuel automotive spark-ignition engine fuels, and related industrial applications.

The standard is essential for laboratories, refineries, fuel producers, and regulators to ensure that ethanol and methanol levels in fuel blends comply with applicable specifications such as ASTM D4806 and ASTM D5798, as well as federal and local fuel regulations.

Key Topics

• Scope and Range:

  • Applicable to ethanol-gasoline blends and hydrocarbon fuels with 20% to 100% ethanol by mass.
  • Methanol quantification range: 0.01% to 0.6% by mass.
  • Not designed for blends with lower ethanol content; for lower ranges, refer to ASTM D5599 and ASTM D4815.

• Methodology:

  • Employs gas chromatography with a flame ionization detector for high-precision analysis.
  • Determines alcohol concentrations by mass, with equations provided to convert values to percent by volume.
  • Water content in samples is not measured by this method and must be determined separately using procedures such as ASTM D7923, E203, or E1064.

• Limitations:

  • Does not detect all individual constituents or components with boiling points above 225°C.
  • Not suitable for impurities with poor flame ionization detector response-including water.
  • Requires adherence to stringent sample collection, calibration, and instrument quality control procedures.

• Regulatory Relevance:

  • Supports compliance with specifications for denatured fuel ethanol (ASTM D4806) and ethanol fuel blends for flexible-fuel vehicles (ASTM D5798).
  • Provides information and guidance for adjusting methodologies to meet local or federal regulatory requirements.

Applications

• Quality Assurance for Ethanol Blends:
  Routine use of ASTM D5501-20 ensures that fuel blends intended for automotive, industrial, and flexible-fuel engines meet rigorous ethanol content standards for performance and compliance.

• Industrial and Laboratory Settings:
  Laboratories use this standard for quality control of denatured and undenatured ethanol, verifying blend ratios, and supporting fuel certification.

• Regulatory Compliance:
  Assists fuel producers and importers in meeting U.S. Environmental Protection Agency (EPA), federal, and local ethanol content regulations.

• Support for Flexible-Fuel Vehicles:
  Validation of proper ethanol concentration in E85 and other high-ethanol blends helps protect engines and promote efficient, low-emission fuel use in modern vehicles.

Related Standards

• ASTM D4806: Specification for Denatured Fuel Ethanol for Blending with Gasolines.
• ASTM D5798: Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines.
• ASTM D5599: Test method for oxygenates in gasoline by gas chromatography and oxygen selective flame ionization.
• ASTM D4815: Test method for lower-concentration ethanol blends.
• ASTM D7923, E203, E1064: Methods for determination of water in ethanol and hydrocarbon blends.
• ASTM D1298, D4052: Methods for density measurement, important for mass-to-volume conversions.

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Keywords: ethanol content determination, methanol quantification, fuel ethanol, gas chromatography, ASTM D5501, high ethanol blends, fuel compliance, ethanol-gasoline blends, quality control, laboratory fuel testing.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5501 − 20
Standard Test Method for
Determination of Ethanol and Methanol Content in Fuels
Containing Greater than 20 % Ethanol by Gas
Chromatography
This standard is issued under the fixed designation D5501; 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* 1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This test method covers the determination of the ethanol
ization established in the Decision on Principles for the
content of hydrocarbon blends containing greater than 20 %
Development of International Standards, Guides and Recom-
ethanol. This method is applicable to denatured fuel ethanol,
mendations issued by the World Trade Organization Technical
ethanol fuel blends, and mid-level ethanol blends.
Barriers to Trade (TBT) Committee.
1.1.1 Ethanolisdeterminedfrom20 %bymassto100 %by
mass and methanol is determined from 0.01 % by mass to
2. Referenced Documents
0.6 % by mass. Equations used to convert these individual
2.1 ASTM Standards:
alcohols from percent by mass to percent by volume are
D1298 Test Method for Density, Relative Density, or API
provided.
Gravity of Crude Petroleum and Liquid Petroleum Prod-
NOTE 1—Fuels containing less than 20 % ethanol may be quantified
ucts by Hydrometer Method
using Test Method D5599, and less than 12 % ethanol may be quantified
D1364 Test Method for Water in Volatile Solvents (Karl
using Test Method D4815.
Fischer Reagent Titration Method)
1.2 This test method does not purport to identify all indi-
D4052 Test Method for Density, Relative Density, and API
vidual components common to ethanol production or those
Gravity of Liquids by Digital Density Meter
components that make up the denaturant or hydrocarbon
D4057 Practice for Manual Sampling of Petroleum and
constituent of the fuel.
Petroleum Products
1.3 Water cannot be determined by this test method and
D4175 Terminology Relating to Petroleum Products, Liquid
shall be measured by a procedure such as Test Method D7923,
Fuels, and Lubricants
E203,or E1064 and the result used to correct the concentra-
D4307 Practice for Preparation of Liquid Blends for Use as
tions determined by this method.
Analytical Standards
D4626 Practice for Calculation of Gas Chromatographic
1.4 This test method is inappropriate for impurities that boil
Response Factors
at temperatures higher than 225 °C or for impurities that cause
D4806 Specification for Denatured Fuel Ethanol for Blend-
poor or no response in a flame ionization detector, such as
ing with Gasolines for Use as Automotive Spark-Ignition
water.
Engine Fuel
1.5 The values stated in SI units are to be regarded as the
D4815 Test Method for Determination of MTBE, ETBE,
standard. The values given in parentheses are provided for
TAME, DIPE, tertiary-Amyl Alcohol and C to C Alco-
1 4
information purposes only.
hols in Gasoline by Gas Chromatography
1.6 This standard does not purport to address all of the
D5599 Test Method for Determination of Oxygenates in
safety concerns, if any, associated with its use. It is the
Gasoline by Gas Chromatography and Oxygen Selective
responsibility of the user of this standard to establish appro-
Flame Ionization Detection
priate safety, health, and environmental practices and deter-
D5798 Specification for Ethanol Fuel Blends for Flexible-
mine the applicability of regulatory limitations prior to use.
Fuel Automotive Spark-Ignition Engines
D6299 Practice for Applying Statistical Quality Assurance
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 D02.04.0L on Hydrocarbon Analysis. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2020. Published May 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1994. Last previous edition approved in 2016 as D5501 – 12 (2016). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D5501-20. 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
D5501 − 20
and Control Charting Techniques to Evaluate Analytical 3.3.1 CFR—U.S. Code of Federal Regulations
Measurement System Performance
3.3.2 EPA—The U.S. Environmental Protection Agency
D6792 Practice for Quality Management Systems in Petro-
3.3.3 MRF—mass response factor
leum Products, Liquid Fuels, and Lubricants Testing
3.3.4 RIN—Renewable Identification Number
Laboratories
D7923 Test Method for Water in Ethanol and Hydrocarbon 3.3.5 RMRF—relative mass response factor
Blends by Karl Fischer Titration
3.3.6 TTB—TheAlcoholandTobaccoTaxandTradeBureau
E203 Test Method for Water Using Volumetric Karl Fischer
of the U.S. Department of Treasury
Titration
E355 Practice for Gas ChromatographyTerms and Relation-
4. Summary of Test Method
ships
4.1 A representative aliquot of the fuel ethanol sample is
E594 Practice for Testing Flame Ionization Detectors Used
introduced into a gas chromatograph equipped with a polydim-
in Gas or Supercritical Fluid Chromatography
ethylsiloxane bonded phase capillary column. Carrier gas
E1064 Test Method for Water in Organic Liquids by Coulo-
transports the vaporized aliquot through the column where the
metric Karl Fischer Titration
components are chromatographically separated in order of
E1510 Practice for Installing Fused Silica Open Tubular
boiling point temperature. Components are sensed by a flame
Capillary Columns in Gas Chromatographs
ionization detector as they elute from the column.The detector
E3237 Specification for Undenatured Ethanol from Biomass
signal is processed by an electronic data acquisition system.
for Use in Industrial Applications
The ethanol and methanol components are identified by com-
2.2 U.S. Federal Standards:
paring their retention times to the ones identified by analyzing
40 CFR 80.1426 How are RINs generated and assigned to
standards under identical conditions. The concentrations of all
batches of renewable fuel by renewable fuel producers or
components are determined in mass percent by normalization
importers?
of the peak areas. After correction for water content, results
27 CFR 30.22 Hydrometers and Thermometers
may be reported in mass percent or volume percent.
27CFR30.67 Table7,forcorrectionofvolumeofspirituous
liquors to 60 °F
5. Significance and Use
5.1 This test method provides a method of determining the
3. Terminology
percentageofethanolinanethanol-gasolinefuelblendoverthe
3.1 Definitions—This test method makes reference to many
range of 20 % by mass to 100 % by mass for compliance with
common chromatographic procedures, terms, and relation-
fuel specifications and federal or local fuel regulations.
ships. Detailed definitions can be found in Terminology
5.2 Ethanol content of denatured fuel ethanol for gasoline
D4175, and Practices E355 and E594.
blending is required in accordance with Specification D4806.
3.2 Definitions:
5.3 Ethanol content of ethanol fuel blends for flexible-fuel
3.2.1 denatured fuel ethanol, n—fuel ethanol made unfit for
automotive spark-ignition engines is required in accordance
beverage use by the addition of denaturants under formula(s)
with Specification D5798.
approved by the applicable regulatory agency to prevent the
imposition of beverage alcohol tax.
5.4 This test method is acceptable for determining the
percentage of ethanol for either denatured fuel ethanol or
3.2.2 mass response factor (MRF), n—constant of propor-
undenatured ethanol for use in industrial applications using
tionality that converts area to mass percent.
Table 3(a) or Table 3(b).
3.2.3 relative mass response factor (RMRF), n—mass re-
5.4.1 Refer to local, federal, or other authorities having
sponse factor of a component divided by that of another
jurisdiction for information regarding the correct implementa-
component.
tion of either Table 3(a) or Table 3(b).
3.2.3.1 Discussion—In this test method, the mass response
5.4.2 Specific regulatory requirements for U.S. domestic
factors are relative to that of n-heptane.
fuel applications are given in Appendix X5 for information.
3.2.4 tangential skimming, n—in gas chromatography, inte-
gration technique used when a “rider” peak elutes on the tail of
6. Apparatus
a primary peak.
6.1 Gas Chromatograph, capable of operating at the condi-
3.2.4.1 Discussion—Since the majority of the area beneath
tions listed in Table 1. A heated flash vaporizing injector
the rider peak belongs to the primary peak, in tangential
designed to provide a linear sample split injection (for
skimming the top of the primary peak tail is used as the
example, 200:1) is required for proper sample introduction.
baselineoftheriderpeak,andthetriangulatedareabeneaththe
Carrier gas controls shall be of adequate precision to provide
rider peak is added to the primary peak.
reproducible column flows and split ratios in order to maintain
3.3 Abbreviations:
analytical integrity. Pressure and flow control devices shall be
designed to attain the linear velocity required in the column
used.Ahydrogen flame ionization detector with associated gas
Available from U.S. Government Printing Office, Superintendent of
controls and electronics, designed for optimum response with
Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://
www.access.gpo.gov. open tubular columns, is required.
D5501 − 20
TABLE 1 Typical Operating Conditions
Analytical Reagents of the American Chemical Society where
Column Temperature Program such specifications are available.
Column length 100 m 150 m
7.2 Carrier Gas, helium or hydrogen, with a minimum
Initial temperature 15 °C 60 °C
Initial hold time 12 min 15 min
purity of 99.95 mol%. Oxygen removal systems and gas
Program rate 30 °C ⁄min 30 °C ⁄min
purifiers should be used. (Warning—Compressed gas under
Final temperature 250 °C 250 °C
high pressure.) Use of hydrogen carrier gas may require
Final hold time 19 min 23 min
Injector
additional safety considerations.
Temperature 300 °C
Split ratio 200:1 7.3 Detector Gases, hydrogen, air, and nitrogen. The mini-
Sample size 0.1 µL to 0.5 µL
mum purity of the gases used should be 99.95 % for the
Detector
hydrogen and nitrogen. The air should be hydrocarbon-free
Type Flame ionization
Temperature 300 °C grade. Gas purifiers are recommended for the detector gases.
Fuel gas Hydrogen (30 mL ⁄min)
(Warning—Hydrogen, extremely flammable gas under high
Oxidizing gas Air (300 mL/min)
pressure.) (Warning—Air and nitrogen, compressed gases
Make-up gas Helium or Nitrogen (30 mL/min)
Date rate 20 Hz under high pressure.)
Carrier Gas
A
7.4 Standards for Calibration and Identification—Standards
Type Helium or Hydrogen
Average linear velocity 21 cm ⁄s to 24 cm/s (constant flow)
of all components to be analyzed are required for establishing
A
Use of hydrogen carrier gas requires additional safety considerations. identification by retention time as well as calibration for
quantitative measurements. These materials shall be of known
purity and free of the other components to be analyzed.
7.4.1 To verify the purity of blend components, analyze
6.2 Sample Introduction—Automatic liquid syringe sample
injection to the splitting injector. Devices capable of 0.1 µL to each compound by the same technique for which the blend is
intended or by another suitable technique.
0.5 µL injections are suitable.
7.4.2 Checkforotherimpuritiessuchaswater.Watercannot
NOTE 2—Inadequate splitter, poor injection technique, and overloading
be determined with sufficient accuracy by most GC methods
the column can result in poor resolution. Avoid overloading, particularly
andshallbemeasuredbyotherproceduressuchasTestMethod
of the ethanol peak, and eliminate this condition during analysis.
D1364, or equivalent, and the result used to normalize the
6.3 Column—The precision for this test method was devel-
chromatographic value. If any of the impurities found are
oped utilizing a fused silica open tubular column with non-
components present in the blend, determine their concentra-
polar polydimethylsiloxane bonded (cross-linked) phase inter-
tions and make appropriate corrections.
nal coating. Any column with equivalent or better
7.4.3 Ethanol—Absolute ethanol, 99.5 % by mass mini-
chromatographic efficiency, resolution, and selectivity to those
mum. Methanol content should be less than 0.01 % by mass.
described in 6.3.1 may be used.
(Warning—Flammableandmaybeharmfulorfatalifingested
6.3.1 Open tubular column with a non-polar polydimethyl-
or inhaled.)
siloxane bonded (cross-linked) phase internal coating, either
7.4.4 Methanol—(Warning—Flammableandmaybeharm-
150 m by 0.25 mm with a 1.0 µm film thickness, or 100 m by
fulorfatal,ifingestedorinhaled.)Minimumpurityof99 %by
0.25 mm with a 0.5 film thickness have been found suitable.
mass, and free of ethanol.
The 150 m column is recommended due to its higher resolu-
7.4.5 Heptane—(Warning—Flammable and may be harm-
tion. Follow Practice E1510 for column installation.
ful or fatal, if ingested or inhaled.)
6.4 Electronic Data Acquisition System—Any data acquisi-
7.4.6 Hydrocarbon Diluent—n-Octane or isooctane, used
tion and integration device used for quantification of these
for preparation of calibration standards. The diluent shall
analyses must meet or exceed these minimum requirements:
contain<0.01 %ofheptane,methanol,orethanol.(Warning—
6.4.1 Capacity for at least 80 peaks/analysis,
Flammable and may be harmful or fatal if ingested or inhaled.)
6.4.2 Normalized percent calculation based on peak area
7.5 Linearity Mixture—A mixture of known composition
and using response factors,
containing 10-20 hydrocarbons, ranging from C5 to C11, used
6.4.3 Identification of individual components based on re-
for split injector linearity testing. (Warning—Flammable and
tention time,
may be harmful or fatal if ingested or inhaled.)
6.4.4 Noise and spike rejection capability,
6.4.5 Sampling rate for narrow (<1 s) peaks,
8. Sampling
6.4.6 Positive and negative sloping baseline correction,
8.1 Denatured ethanol may be sampled into an open con-
6.4.7 Peak detection sensitivity compensation for narrow
tainer since a vapor pressure of less than 21 kPa (3 psi) is
and broad peaks, and
expected. Refer to Practice D4057 for instruction on manual
6.4.8 Capable of integrating non-resolved peaks by perpen-
dicular drop or tangential skimming as needed.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
7. Reagents and Materials
Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
7.1 Purity of Reagents—Reagent grade chemicals shall be
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
used in all tests. Unless otherwise indicated, it is intended that
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
all reagents conform to the specifications of the Committee on copeial Convention, Inc. (USPC), Rockville, MD.
D5501 − 20
sampling from bulk storage into open containers. Stopper the 9.4.2 The injector split linearity is dependent on the nature
container immediately after drawing the sample. of the compound (boiling point, molecular weight, etc.) splitter
and liner design, injection volume, and the linear velocity of
8.2 To minimize loss of hydrocarbon light ends, chill the
sample through the inlet. Establish the splitting injector linear-
sample before transferring an aliquot into an auto sampler vial.
ity to determine the proper quantitative parameters and limits.
Seal immediately. Obtain the test sample for analysis directly
Analyzethelinearitymixture,7.5,followingthegaschromato-
from the sealed auto sampler vial.
graphic analysis procedure in Section 12. Calculate the nor-
9. Preparation and Verification of Apparatus malized mass percent (using Eq 8, Eq 5, and Eq 6) of each
component using a relative mass response factor of 1 for all
9.1 Install and condition the column in accordance with the
hydrocarbon compounds. The determined mass percent for
manufacturer’s or supplier’s instructions. After conditioning,
each component shall match the gravimetric known concen-
attach column outlet to flame ionization detector inlet and
tration within 63 % relative.
check for leaks throughout the system. When leaks are found,
9.4.3 Verify the linearity of the flame ionization detector
tighten or replace fittings before proceeding.
(FID).RefertoPracticeE594forasuggestedprocedure.Aplot
9.2 Adjustthecarriergasflowratesothattheaveragelinear
ofthepeakareasversusconcentrationforpreparedmethanolor
gas velocity, at the initial temperature of the run, is between
ethanol standards in the concentration range of interest should
21 cm⁄s and 24 cm⁄s, as determined by Eq 1. Flow rate
be linear. If the plot is not linear or does not conform to these
adjustment is made by raising or lowering the carrier gas
requirements then adjust the split ratio.
pressure (head pressure) to the injector. Maintain constant flow
throughout the analysis.
9.5 Resolution and Integration:
9.5.1 Optimize the system to resolve methanol from isobu-
L
µ¯ 5 (1)
tane on the 150 m column using the conditions in this method.
t
m
With higher amounts of isobutane, the possibility for coelution
where:
increases. Improved resolution has been achieved by optimiz-
µ¯ = average linear gas velocity (cm/s),
ing the linear velocity to 24 cm⁄s. See Fig. 1.
L = column length (cm), and
9.5.2 Methanol might not be completely resolved from
t = retention time of methane.
m
Butene-1/Isobutylene on the 100 m column using the condi-
9.3 Adjust the operating conditions of the gas chromato-
tions in this method. Use tangential skimming to properly
graph (Table 1) and allow the system to equilibrate.
integrate the methanol.
9.5.3 Ethanol might not be completely resolved from
9.4 Linearity—The linearity of the gas chromatograph sys-
tem shall be established prior to the analysis of samples. 3-methyl-1-butene. If so, use tangential skimming to integrate
the ethanol. See Fig. 2.
9.4.1 The optimal split ratio is dependent upon the split
linearity characteristics of the particular injector and the
9.5.4 Set integration parameters such that any component of
sample capacity of the column. The capacity of a particular
at least 0.002 % by mass is integrated.
column for a sample component is dependent on the amount
9.6 Peak Shape:
and polarity of the liquid phase (loading or film thickness) and
9.6.1 System overload of ethanol can be determined upon
the ratio of the column temperature to the component boiling
visual inspection of the peak. A flat top indicates electronic
point (vapor pressure). Overloading of the column can cause
saturation.Awide“fin”shapecanindicatecolumnoverload.In
loss of resolution for some components and, since overloaded
either case, investigate and make adjustments.
peaks are skewed, variance in retention times. This can lead to
erroneous component identification. During column evalua- 9.6.2 Hydrocarbon peaks shall be symmetrical. Slight tail-
tions and split linearity studies, be aware of any peaks that ing of polar compounds (methanol, ethanol) is typical, but
appear front skewed, indicating column overload. Note the excessive tailing should be investigated. Verify that the inlet
component size and avoid conditions leading to this problem liners are thoroughly deactivated and the column shows
during actual analysis. Refer to Practice E594 for further appropriate deactivation towards methanol and ethanol. Fig. 3
guidance. shows an example of poor chromatography.
D5501 − 20
FIG. 1 Chromatogram Overlay Showing Possible Methanol Interferences on 150 m Column
FIG. 2 Integration of Methanol and Ethanol on 100 m Column Using Tangential Skimming
D5501 − 20
NOTE 1—Excessive tailing and delayed elution may result from adsorption, dead volume, or damaged column.
FIG. 3 Example of Poor Chromatography
10. Calibration and Standardization –3 % and +3 % by mass (see Note 3). If the plot does not
conform to these requirements, troubleshoot the system and
10.1 Identification—Determine the retention time of ethanol
repeat the analyses using fresh vials of standard until require-
andmethanolbyinjectingamountsofeach,eitherseparatelyor
ments are met. Typical troubleshooting measures include
in known mixtures, in concentrations expected in the final
increasing the split ratio, reducing the injection amount,
blend.
correcting the integration of the ethanol and methanol peaks,
10.2 Calibration Standards:
andcheckingforactivesitesincolumnandinletliner.Example
10.2.1 Determine the purity of the oxygenate reagents and
linearity plots for ethanol are given in Fig. 5.
make corrections for the impurities found. Whenever possible,
10.4 Calibration—Calibration techniques may be classified
usestockchemicalsofatleast99.5 %purity.Correctthepurity
as absolute or relative, and are typically dictated by the
of the components for water content, determined by Test
chromatographic software. Only after linearity is established,
Method D1364 or equivalent. Example calculations are pre-
calibrate with one of the techniques below.
sented in Appendix X1.
10.4.1 Absolute Calibration—Establishthecorrectionfactor
10.2.2 Gravimetrically prepare standards that are blended
or equation that directly relates the peak area to the component
according to Practice D4307. Chill components prior to blend-
concentration. If available, multi-point calibration is preferred.
ing. Prepare standards that cover the expected range of ethanol
10.4.1.1 Single-point—Calculate the mass response factor
and methanol in a hydrocarbon diluent (n-octane or isooctane)
(MRF) of ethanol in each calibration standard using Eq 2
and containing a known amount of heptane. Examples of
according to Practice D4626. The average response factor
standards covering the range of 20 % by mass to 99 % by mass
determineateachconcentrationshallbeusedinthecalibration.
ethanol are given in Table 2.
Repeat for methanol and heptane.Assign the heptane response
10.3 Calibration Linearity—Analyze the standards from
factor to any unknowns.
10.2 according to the procedure in Section 12. An example
MRF 5 mass% ⁄area (2)
~i! ~i! ~i!
chromatogram is found in Fig. 4. For ethanol, methanol, and
n-heptane, the plot of the peak areas versus concentration shall
where:
be linear with a minimum r of 0.995. Do not force the ethanol
MRF = the mass response factor of component i,
(i)
calibration through the origin (zero). For ethanol, a peak area
Mass% = the mass percent of component i, and
(i)
of zero shall correspond to an ethanol concentration between
Area = the peak area of component i.
(i)
10.4.1.2 Multi-point—With this technique, calibration and
TABLE 2 Recommended Matrix of Calibration Standards Ranging
linearity verification may be completed in the same step.
from 20 % to 99 % by Mass
Analyze the standards prepared in 10.2, according to the
Mix 1 Mix 2 Mix 3 Mix 4 Mix 5
procedureinSection12.Generateindividualcalibrationcurves
Methanol, % by mass 0.6 0.5 0.3 0.2 0.1
for methanol, ethanol, and heptane following the software
Ethanol, % by mass 20.0 50.0 75.0 90.0 99.4
manufacturer’s instructions. Calibration curves shall
...

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: D5501 − 12 (Reapproved 2016) D5501 − 20
Standard Test Method for
Determination of Ethanol and Methanol Content in Fuels
Containing Greater than 20%20 % Ethanol by Gas
Chromatography
This standard is issued under the fixed designation D5501; 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 ethanol content of hydrocarbon blends containing greater than 20 %
ethanol. This method is applicable to denatured fuel ethanol, ethanol fuel blends, and mid-level ethanol blends.
1.1.1 Ethanol is determined from 20 % by mass to 100 % by mass and methanol is determined from 0.01 % by mass to 0.6 %
by mass. Equations used to convert these individual alcohols from percent by mass to percent by volume are provided.
NOTE 1—Fuels containing less than 20 % ethanol may be quantified using Test Method D5599, and less than 12 % ethanol may be quantified using
Test Method D4815.
1.2 This test method does not purport to identify all individual components common to ethanol production or those components
that make up the denaturant or hydrocarbon constituent of the fuel.
1.3 Water cannot be determined by this test method and shall be measured by a procedure such as Test Method D1364D7923,
E203, or E1064 and the result used to correct the concentrations determined by this method.
1.4 This test method is inappropriate for impurities that boil at temperatures higher than 225 °C or for impurities that cause poor
or no response in a flame ionization detector, such as water.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information
purposes only.
1.6 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by
Hydrometer Method
D1364 Test Method for Water in Volatile Solvents (Karl Fischer Reagent Titration Method)
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
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D4626 Practice for Calculation of Gas Chromatographic Response Factors
D4806 Specification for Denatured Fuel Ethanol for Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel
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
D02.04.0L on Hydrocarbon Analysis.
Current edition approved Oct. 1, 2016May 1, 2020. Published November 2016May 2020. Originally approved in 1994. Last previous edition approved in 20122016 as
ɛ1
D5501 – 12 (2016). . DOI: 10.1520/D5501-12R16.10.1520/D5501-20.
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.
*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
D5501 − 20
D4815 Test Method for Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C to C Alcohols in
1 4
Gasoline by Gas Chromatography
D5599 Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame
Ionization Detection
D5798 Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines
D6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical Measure-
ment System Performance
D6792 Practice for Quality Management Systems in Petroleum Products, Liquid Fuels, and Lubricants Testing Laboratories
D7923 Test Method for Water in Ethanol and Hydrocarbon Blends by Karl Fischer Titration
E203 Test Method for Water Using Volumetric Karl Fischer Titration
E355 Practice for Gas Chromatography Terms and Relationships
E594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
E1064 Test Method for Water in Organic Liquids by Coulometric Karl Fischer Titration
E1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs
E3237 Specification for Undenatured Ethanol from Biomass for Use in Industrial Applications
2.2 U.S. Federal Standards:
40 CFR 80.1426 How are RINs generated and assigned to batches of renewable fuel by renewable fuel producers or importers?
27 CFR 30.22 Hydrometers and Thermometers
27 CFR 30.67 Table 7, for correction of volume of spirituous liquors to 60 °F
3. Terminology
3.1 Definitions—This test method makes reference to many common chromatographic procedures, terms, and relationships.
Detailed definitions can be found in Terminology D4175, and Practices E355 and E594.
3.2 Definitions:
3.2.1 denatured fuel ethanol, n—fuel ethanol made unfit for beverage use by the addition of denaturants under formula(s)
approved by the applicable regulatory agency to prevent the imposition of beverage alcohol tax.
3.2.2 mass response factor (MRF), n—constant of proportionality that converts area to mass percent.
3.2.3 relative mass response factor (RMRF), n—mass response factor of a component divided by that of another component.
3.2.3.1 Discussion—
In this test method, the mass response factors are relative to that of n-heptane.
3.2.4 tangential skimming, n—in gas chromatography, integration technique used when a “rider” peak elutes on the tail of a
primary peak.
3.2.4.1 Discussion—
Since the majority of the area beneath the rider peak belongs to the primary peak, in tangential skimming the top of the primary
peak tail is used as the baseline of the rider peak, and the triangulated area beneath the rider peak is added to the primary peak.
3.3 Abbreviations:
3.3.1 CFR—U.S. Code of Federal Regulations
3.3.2 EPA—The U.S. Environmental Protection Agency
3.3.3 MRF—mass response factor
3.3.4 RIN—Renewable Identification Number
3.3.5 RMRF—relative mass response factor
3.3.6 TTB—The Alcohol and Tobacco Tax and Trade Bureau of the U.S. Department of Treasury
4. Summary of Test Method
4.1 A representative aliquot of the fuel ethanol sample is introduced into a gas chromatograph equipped with a polydimeth-
ylsiloxane bonded phase capillary column. Carrier gas transports the vaporized aliquot through the column where the components
are chromatographically separated in order of boiling point temperature. Components are sensed by a flame ionization detector as
they elute from the column. The detector signal is processed by an electronic data acquisition system. The ethanol and methanol
components are identified by comparing their retention times to the ones identified by analyzing standards under identical
Available from U.S. Government Printing Office, Superintendent of Documents, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://www.access.gpo.gov.
D5501 − 20
conditions. The concentrations of all components are determined in mass percent by normalization of the peak areas. After
correction for water content, results may be reported in mass percent or volume percent.
5. Significance and Use
5.1 This test method provides a method of determining the percentage of ethanol in an ethanol-gasoline fuel blend over the
range of 20 % by mass to 100 % by mass for compliance with fuel specifications and federal or local fuel regulations.
5.2 Ethanol content of denatured fuel ethanol for gasoline blending is required in accordance with Specification D4806.
5.3 Ethanol content of ethanol fuel blends for flexible-fuel automotive spark-ignition engines is required in accordance with
Specification D5798.
5.4 This test method is acceptable for determining the percentage of ethanol for either denatured fuel ethanol or undenatured
ethanol for use in industrial applications using Table 3(a) or Table 3(b).
5.4.1 Refer to local, federal, or other authorities having jurisdiction for information regarding the correct implementation of
either Table 3(a) or Table 3(b).
5.4.2 Specific regulatory requirements for U.S. domestic fuel applications are given in Appendix X5 for information.
6. Apparatus
6.1 Gas Chromatograph, capable of operating at the conditions listed in Table 1. A heated flash vaporizing injector designed
to provide a linear sample split injection (for example, 200:1) is required for proper sample introduction. Carrier gas controls shall
be of adequate precision to provide reproducible column flows and split ratios in order to maintain analytical integrity. Pressure
and flow control devices shall be designed to attain the linear velocity required in the column used. A hydrogen flame ionization
detector with associated gas controls and electronics, designed for optimum response with open tubular columns, is required.
6.2 Sample Introduction—Automatic liquid syringe sample injection to the splitting injector. Devices capable of 0.1 μL to
0.5 μL injections are suitable.
NOTE 2—Inadequate splitter, poor injection technique, and overloading the column can result in poor resolution. Avoid overloading, particularly of the
ethanol peak, and eliminate this condition during analysis.
6.3 Column—The precision for this test method was developed utilizing a fused silica open tubular column with non-polar
polydimethylsiloxane bonded (cross-linked) phase internal coating. Any column with equivalent or better chromatographic
efficiency, resolution, and selectivity to those described in 6.3.1 may be used.
6.3.1 Open tubular column with a non-polar polydimethylsiloxane bonded (cross-linked) phase internal coating, either 150 m
by 0.25 mm with a 1.0 μm film thickness, or 100 m by 0.25 mm with a 0.5 film thickness have been found suitable. The 150 m
column is recommended due to its higher resolution. Follow Practice E1510 for column installation.
6.4 Electronic Data Acquisition System—Any data acquisition and integration device used for quantification of these analyses
must meet or exceed these minimum requirements:
6.4.1 Capacity for at least 80 peaks/analysis,
6.4.2 Normalized percent calculation based on peak area and using response factors,
6.4.3 Identification of individual components based on retention time,
TABLE 1 Typical Operating Conditions
Column Temperature Program
Column length 100 m 150 m
Initial temperature 15 °C 60 °C
Initial hold time 12 min 15 min
Program rate 30 °C ⁄min 30 °C ⁄min
Final temperature 250 °C 250 °C
Final hold time 19 min 23 min
Injector
Temperature 300 °C
Split ratio 200:1
Sample size 0.1 μL to 0.5 μL
Detector
Type Flame ionization
Temperature 300 °C
Fuel gas Hydrogen (30 mL ⁄min)
Oxidizing gas Air (300 mL/min)
Make-up gas Helium or Nitrogen (30 mL/min)
Date rate 20 Hz
Carrier Gas
A
Type Helium or Hydrogen
Average linear velocity 21 cm ⁄s to 24 cm/s (constant flow)
A
Use of hydrogen carrier gas requires additional safety considerations.
D5501 − 20
6.4.4 Noise and spike rejection capability,
6.4.5 Sampling rate for narrow (<1 s) peaks,
6.4.6 Positive and negative sloping baseline correction,
6.4.7 Peak detection sensitivity compensation for narrow and broad peaks, and
6.4.8 Capable of integrating non-resolved peaks by perpendicular drop or tangential skimming as needed.
7. Reagents and Materials
7.1 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.
7.2 Carrier Gas, helium or hydrogen, with a minimum purity of 99.95 mol%. Oxygen removal systems and gas purifiers should
be used. (Warning—Compressed gas under high pressure.) Use of hydrogen carrier gas may require additional safety
considerations.
7.3 Detector Gases, hydrogen, air, and nitrogen. The minimum purity of the gases used should be 99.95 % for the hydrogen and
nitrogen. The air should be hydrocarbon-free grade. Gas purifiers are recommended for the detector gases. (Warning—Hydrogen,
extremely flammable gas under high pressure.) (Warning—Air and nitrogen, compressed gases under high pressure.)
7.4 Standards for Calibration and Identification—Standards of all components to be analyzed are required for establishing
identification by retention time as well as calibration for quantitative measurements. These materials shall be of known purity and
free of the other components to be analyzed.
7.4.1 To verify the purity of blend components, analyze each compound by the same technique for which the blend is intended
or by another suitable technique.
7.4.2 Check for other impurities such as water. Water cannot be determined with sufficient accuracy by most GC methods and
shall be measured by other procedures such as Test Method D1364, or equivalent, and the result used to normalize the
chromatographic value. If any of the impurities found are components present in the blend, determine their concentrations and
make appropriate corrections.
7.4.3 Ethanol—Absolute ethanol, 99.5 minimum99.5 % by mass percent.minimum. Methanol content should be less than 0.01
mass percent.0.01 % by mass. (Warning—Flammable and may be harmful or fatal if ingested or inhaled.)
7.4.4 Methanol—(Warning—Flammable and may be harmful or fatal, if ingested or inhaled.) Minimum purity of 99 mass
percent,99 % by mass, and free of ethanol.
7.4.5 Heptane—(Warning—Flammable and may be harmful or fatal, if ingested or inhaled.)
7.4.6 Hydrocarbon Diluent—n-Octane or isooctane, used for preparation of calibration standards. The diluent shall contain
<0.01 % of heptane, methanol, or ethanol. (Warning—Flammable and may be harmful or fatal if ingested or inhaled.)
7.5 Linearity Mixture—A mixture of known composition containing 10-20 hydrocarbons, ranging from C5 to C11, used for split
injector linearity testing. (Warning—Flammable and may be harmful or fatal if ingested or inhaled.)
8. Sampling
8.1 Denatured ethanol may be sampled into an open container since a vapor pressure of less than 21 kPa (3 psi) is expected.
Refer to Practice D4057 for instruction on manual sampling from bulk storage into open containers. Stopper the container
immediately after drawing the sample.
8.2 To minimize loss of hydrocarbon light ends, chill the sample before transferring an aliquot into an auto sampler vial. Seal
immediately. Obtain the test sample for analysis directly from the sealed auto sampler vial.
9. Preparation and Verification of Apparatus
9.1 Install and condition the column in accordance with the manufacturer’s or supplier’s instructions. After conditioning, attach
column outlet to flame ionization detector inlet and check for leaks throughout the system. When leaks are found, tighten or replace
fittings before proceeding.
9.2 Adjust the carrier gas flow rate so that the average linear gas velocity, at the initial temperature of the run, is between
21 cm ⁄s and 24 cm ⁄s, as determined by Eq 1. Flow rate adjustment is made by raising or lowering the carrier gas pressure (head
pressure) to the injector. Maintain constant flow throughout the analysis.
L
μ¯ 5 (1)
t
m
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For Suggestionssuggestions on the testing of reagents not listed by the American Chemical Society, see
AnnualAnalar 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.
D5501 − 20
where:
μ¯ = average linear gas velocity (cm/s),
L = column length (cm), and
t = retention time of methane.
m
9.3 Adjust the operating conditions of the gas chromatograph (Table 1) and allow the system to equilibrate.
9.4 Linearity—The linearity of the gas chromatograph system shall be established prior to the analysis of samples.
9.4.1 The optimal split ratio is dependent upon the split linearity characteristics of the particular injector and the sample capacity
of the column. The capacity of a particular column for a sample component is dependent on the amount and polarity of the liquid
phase (loading or film thickness) and the ratio of the column temperature to the component boiling point (vapor pressure).
Overloading of the column can cause loss of resolution for some components and, since overloaded peaks are skewed, variance
in retention times. This can lead to erroneous component identification. During column evaluations and split linearity studies, be
aware of any peaks that appear front skewed, indicating column overload. Note the component size and avoid conditions leading
to this problem during actual analysis. Refer to Practice E594 for further guidance.
9.4.2 The injector split linearity is dependent on the nature of the compound (boiling point, molecular weight, etc.) splitter and
liner design, injection volume, and the linear velocity of sample through the inlet. Establish the splitting injector linearity to
determine the proper quantitative parameters and limits. Analyze the linearity mixture, 7.5, following the gas chromatographic
analysis procedure in Section 12. Calculate the normalized mass percent (using Eq 8, Eq 5, and Eq 6) of each component using
a relative mass response factor of 1 for all hydrocarbon compounds. The determined mass percent for each component shall match
the gravimetric known concentration within 63 % relative.
9.4.3 Verify the linearity of the flame ionization detector (FID). Refer to Practice E594 for a suggested procedure. A plot of the
peak areas versus concentration for prepared methanol or ethanol standards in the concentration range of interest should be linear.
If the plot is not linear or does not conform to these requirements then adjust the split ratio.
9.5 Resolution and Integration:
9.5.1 Optimize the system to resolve methanol from isobutane on the 150 m column using the conditions in this method. With
higher amounts of isobutane, the possibility for coelution increases. Improved resolution has been achieved by optimizing the
linear velocity to 24 cm ⁄s. See Fig. 1.
FIG. 1 Chromatogram Overlay Showing Possible Methanol Interferences on 150 m Column
D5501 − 20
9.5.2 Methanol might not be completely resolved from Butene-1/Isobutylene on the 100 m column using the conditions in this
method. Use tangential skimming to properly integrate the methanol.
9.5.3 Ethanol might not be completely resolved from 3-methyl-1-butene. If so, use tangential skimming to integrate the ethanol.
See Fig. 2.
9.5.4 Set integration parameters such that any component of at least 0.002 % by mass is integrated.
9.6 Peak Shape:
9.6.1 System overload of ethanol can be determined upon visual inspection of the peak. A flat top indicates electronic saturation.
A wide “fin” shape can indicate column overload. In either case, investigate and make adjustments.
9.6.2 Hydrocarbon peaks shall be symmetrical. Slight tailing of polar compounds (methanol, ethanol) is typical, but excessive
tailing should be investigated. Verify that the inlet liners are thoroughly deactivated and the column shows appropriate deactivation
towards methanol and ethanol. Fig. 3 shows an example of poor chromatography.
FIG. 2 Integration of Methanol and Ethanol on 100 m Column Using Tangential Skimming
D5501 − 20
NOTE 1—Excessive tailing and delayed elution may result from adsorption, dead volume, or damaged column.
FIG. 3 Example of Poor Chromatography
10. Calibration and Standardization
10.1 Identification—Determine the retention time of ethanol and methanol by injecting amounts of each, either separately or in
known mixtures, in concentrations expected in the final blend.
10.2 Calibration Standards:
10.2.1 Determine the purity of the oxygenate reagents and make corrections for the impurities found. Whenever possible, use
stock chemicals of at least 99.5 % purity. Correct the purity of the components for water content, determined by Test Method
D1364 or equivalent. Example calculations are presented in Appendix X1.
10.2.2 Gravimetrically prepare standards that are blended according to Practice D4307. Chill components prior to blending.
Prepare standards that cover the expected range of ethanol and methanol in a hydrocarbon diluent (n-octane or isooctane) and
containing a known amount of heptane. Examples of standards covering the range of 20 % by mass to 99 % by mass ethanol are
given in Table 2.
10.3 Calibration Linearity—Analyze the standards from 10.2 according to the procedure in Section 12. An example
chromatogram is found in Fig. 4. For ethanol, methanol, and n-heptane, the plot of the peak areas versus concentration shall be
linear with a minimum r of 0.995. Do not force the ethanol calibration through the origin (zero). For ethanol, a peak area of zero
shall correspond to an ethanol concentration between –3 % and +3 % by mass (see Note 3). If the plot does not conform to these
requirements, troubleshoot the system and repeat the analyses using fresh vials of standard until requirements are met. Typical
troubleshooting measures include increasing the split ratio, reducing the injection amount, correcting the integration of the ethanol
and methanol peaks, and checking for active sites in column and inlet liner. Example linearity plots for ethanol are given in Fig.
5.
10.4 Calibration—Calibration techniques may be classified as absolute or relative, and are typically dictated by the
chromatographic software. Only after linearity is established, calibrate with one of the techniques below.
10.4.1 Absolute Calibration—Establish the correction factor or equation that directly relates the peak area to the component
concentration. If available, multi-point calibration is preferred.
10.4.1.1 Single-point—Calculate the mass response factor (MRF) of ethanol in each calibration standard using Eq 2 according
to Practice D4626. The average response factor determine at each concentration shall be used in the calibration. Repeat for
methanol and heptane. Assign the heptane response factor to any unknowns.
TABLE 2 Recommended Matrix of Calibration Standards Ranging
from 20 % to 99 % by Mass
Mix 1 Mix 2 Mix 3 Mix 4 Mix 5
Methanol, % by mass 0.6 0.5 0.3 0.2 0.1
Ethanol, % by mass 20.0 50.0 75.0 90.0 99.4
Heptane, % by mass 10.0 10.0 10.0 4.0 0.5
A
Hydrocarbon diluent, 69.4 39.5 14.8 5.8 0.0
% by mass
A
Hydrocarbon diluent is free of heptane and any other compounds that would
interfere with the calibration. See 7.4.
D5501 − 20
FIG. 4 Sample Chromatogram of Calibration Mixture on 150 m Column
MRF 5 mass% ⁄area (2)
~i! ~i! ~i!
where:
MRF = the mass response factor of component i,
(i)
Mass% = the mass percent of component i, and
(i)
Area = the peak area of component i.
(i)
10.4.1.2 Multi-point—With this technique,
...