ASTM D5845-21

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Designation: D5845 − 01 (Reapproved 2016) D5845 − 21
Standard Test Method for
Determination of MTBE, ETBE, TAME, DIPE, Methanol,
Ethanol and tert-Butanol in Gasoline by Infrared
Spectroscopy
This standard is issued under the fixed designation D5845; 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 methanol, ethanol, tert-butanol, methyl tert-butyl ether (MTBE), ethyl tert-butyl
ether (ETBE), tert-amyl methyl ether (TAME), and diisopropyl ether (DIPE) in gasoline by infrared spectroscopy. The test method
is suitable for determining methanol from 0.1 to 6 mass %,1.7 % to 5.5 % by mass, ethanol from 0.1 to 11 mass %,1.5 % to 10 %
by mass, tert-butanol from 0.1 to 14 mass %, and DIPE, MTBE, ETBE 1.6 % to 12 % by mass, DIPE from 1.2 % to 17 % by mass,
MTBE from 2.0 % to 16.4 % by mass, ETBE from 2.0 % to 18.5 % by mass, and TAME from 0.1 to 20 mass %.1.5 % to 18.5 %
by mass.
1.2 This test method is applicable to oxygenate(s) in gasoline singularly or in multiple mixtures hereof according to the oxygenates
and mass percent ranges given in 1.1.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
1.5 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
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
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
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
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
D02.04.0F on Absorption Spectroscopic Methods.
Current edition approved Oct. 1, 2016Oct. 1, 2021. Published November 2016November 2021. Originally approved in 1995. Last previous edition approved in 20112016
as D5845 – 01 (2011).(2016). DOI: 10.1520/D5845-01R16.10.1520/D5845-21.
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
D5845 − 21
D5599 Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame
Ionization Detection
E1655D8321 Practices for Infrared Multivariate Quantitative AnalysisPractice for Development and Validation of Multivariate
Analyses for Use in Predicting Properties of Petroleum Products, Liquid Fuels, and Lubricants based on Spectroscopic
Measurements
NOTE 1—D5845 was developed with reference to E1655. A significant enhancement has been made to E1655 and is designated as D8321. D8321 is the
preferred standard Practice and describes the mathematics, that is, the regression algorithms to develop calibration equations that are also described in
E1655. Replace E1655 with D8321.
NOTE 2—Surrogate methods such as D5845 may indicate that they make use of the creation of multivariate calibration equations described therein D8321,
but they should not claim to follow the procedures described herein.
2.2 Other Standard:
GC/OFID EPA Test Method—Oxygen and Oxygenate Content Analysis (by way of gas chromatography with oxygen-selective
flame ionization detection)
3. Terminology
3.1 Definitions:
3.1.1 diluent, n—a substance used to dilute something.
3.1.1.1 Discussion—
In this standard, the diluents are termed base gasoline A, B, and C, which are the diluents consisting of gasoline blend stocks used
to dissolve the oxygenates to create the calibration and instrument qualification matrix solutions. The base stocks must not contain
measurable oxygenates. The known base socks are:
(1) Base gasoline A should be a gasoline with at least 60 % alkylate. A suggested recipe for base gasoline A is 60 % alkylate,
30 % full range reformate, and 10 % light straight run.
(2) Base gasoline B should be a gasoline with at least 60 % full range reformate. A suggested recipe for base gasoline B is
60 % full range reformate, 30 % FCC gasoline, and 10 % light straight run.
(3) Base gasoline C the composition is not known
3.1.2 multivariate calibration, n—a process for creating a calibration model in which multivariate mathematics is applied to
correlate the absorbances measured for a set of calibration samples to reference component concentrations or property values for
the set of samples. The resultant multivariate calibration model is applied to the analysis of spectra of unknown samples to provide
an estimate of the component concentration or property values for the unknown sample.
3.1.3 oxygenate, n—an oxygen-containing organic compound, which may be used as a fuel or fuel supplement, for example,
various alcohols or ethers.a molecule composed solely of carbon, hydrogen, and oxygen.
3.1.3.1 Discussion—
In this standard, the oxygenates of interest are: methanol, ethanol, tert-butanol, DIPE, MTBE, ETBE, and TAME.
4. Summary of Test Method
4.1 A sample of gasoline is introduced into a liquid sample cell. A beam of infrared light is imaged through the sample onto a
detector, and the detector response is determined. Regions of the infrared spectrum are selected for use in the analysis by either
placing highly selective bandpass filters before or after the sample or mathematically selecting the regions after the whole spectrum
is obtained. A multivariate mathematical analysis is carried out which convertsuses the detector response for the selected regions
in the spectrum of an unknown to a to compute the concentration for each component in an unknown based on multivariate models
for each component.
5. Significance and Use
5.1 Alcohols and ethers are added to gasoline to produce a reformulated lower emissions gasoline. Alcohols and ethers may also
be added to gasoline to increase the octane number. Type and concentration of various oxygenates are specified and regulated to
ensure acceptable commercial gasoline quality. Driveability, vapor pressure, phase separation, and evaporative emissions are some
of the concerns associated with oxygenated fuels.
Code of Federal Regulations, Part 80 of Title 40, Section 80.46(g); also published in the Federal Register, Volume 59, No. 32, February 16, 1994, p 7828.
D5845 − 21
5.2 This test method is faster, simpler, less expensive and more portable than current methods.
5.3 This test method may be applicable for quality control in the production of gasoline.
5.4 This test method is not suitable for testing for compliance with federal regulations.
5.5 False positive readings for some of the samples tested in the round robin were sometimes observed. As only extreme base
gasolines were tested in the round robin, no definitive statement can be made as to the expected frequency or magnitude of false
positives expected in a wider range of base gasolines.
6. Apparatus
6.1 Mid-IR Spectrometric Analyzer, of one of the following types:
6.1.1 Filter-based Mid-IR Test Apparatus—The type of apparatus suitable for use in this test method minimally employs an IR
source, an infrared transmission cell or a liquid attenuated total internal reflection cell, wavelength discriminating filters, a chopper
wheel, a detector, an A-D converter, a microprocessor, and a sample introduction system.
6.1.2 Fourier Transform Mid-IR Test Apparatus—The type of apparatus suitable for use in this test method employs an IR source,
an infrared transmission cell or a liquid attenuated total internal reflection cell, a scanning interferometer, a detector, an A-D
converter, a microprocessor and a sample introduction system.
6.1.3 Dispersive Mid-IR Test Apparatus—The type of apparatus suitable for use in this test method minimally employs an IR
source, an infrared transmission cell or a liquid attenuated total internal reflection cell, a wavelength dispersive element such as
a grating or prism, a chopper wheel, a detector, an A-D converter, a microprocessor and a sample introduction system.
7. Reagents and Materials
7.1 Samples for Calibration and Quality Control Check Solutions—Use of chemicals of at least 99 % purity is highly
recommended when preparing calibration and quality control check samples. If reagents of high purity are not available, an
accurate assay of the reagent must be performed using a properly calibrated GC or other techniques (for example, water
determination).
7.1.1 Base gasolines containing no oxygenates,
7.1.2 Methanol,
7.1.3 Ethanol,
7.1.4 tert-Butanol,
7.1.5 Methyl tert-butyl ether, MTBE,
7.1.6 Ethyl tert-butyl ether, ETBE,
7.1.7 tert-Amyl methyl ether, TAME, and
7.1.8 Diisopropyl ether, DIPE.
7.2 Warning—These materials are flammable and may be harmful if ingested or inhaled.
8. Sampling and Sample Handling
8.1 General Requirements:
8.1.1 Gasoline samples must be handled with meticulous care to prevent evaporative loss and composition changes.
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8.1.2 Gasoline samples to be analyzed by the test method shall be obtained using method(s) specified by governmental regulatory
agencies or by the procedures outlined in Practice D4057 (or equivalent). Do not use the “Sampling by Water Displacement”
method as some alcohols or ethers might be extracted into the water phase.
8.1.3 Protect samples from excessive temperatures prior to testing. This can be accomplished by storage in an appropriate ice bath
or refrigerator at 0 °C to 5 °C.
8.1.4 Do not test samples stored in leaky containers. Discard and obtain a new sample if leaks are detected.
8.1.5 Perform the oxygenate determination on fresh samples from containers that are at least 80 % full. If sample containers are
less than 80 % full or have been opened and sampled multiple times, a new sample shall be obtained.
8.2 Sample Handling During Analysis:
8.2.1 Prior to the analysis of samples by infrared spectroscopy, the samples should be allowed to equilibrate to the temperature
at which they should be analyzed (15 °C to 38 °C).
8.2.2 After withdrawing the sample, reseal the container, and store the sample in an ice bath or a refrigerator at 0 °C to 5 °C.
9. Preparation, Calibration, and Qualification of the Infrared Test Apparatus
9.1 Preparation—Prepare the instrument for operation in accordance with the manufacturer’s instructions.
9.2 Calibration—Each instrument must be calibrated by the manufacturer or user in accordance with Practice E1655D8321. This
practice serves as a guide for the multivariate calibration of infrared spectrometers used in determining the physical characteristics
of petroleum and petrochemical products. The procedures describe treatment of the data, development of the calibration, and
qualification of the instrument. Note that bias and slope adjustments are specifically not recommended to improve calibration or
prediction statistics for IR multivariate models.
9.3 Qualification of Instrument—The instrument must be qualified according to the procedure in Annex A1 to ensure that the
instrument accurately and precisely measures each oxygenate in the presence of typical gasoline compounds or other oxygenates
that, in typical concentrations, present spectral interferences. General classes of compounds that will cause interferences include
aromatics, branched aliphatic hydrocarbons, and other oxygenates.
TABLE 1 Recommended Concentrations for Individual Quality
Control Standards
Concentration to Attain
Oxygenate
2.0 mass % O 2.7 mass % O 3.5 mass % O
Methanol 4.00 mass % 5.41 mass %
Ethanol 5.76 mass % 7.77 mass % 10.1 mass %
tert-Butanol 9.26 mass % 12.5 mass %
MTBE 11.0 mass % 14.9 mass %
TAME 12.8 mass % 17.2 mass %
DIPE 12.8 mass % 17.2 mass %
ETBE 12.8 mass % 17.2 mass %
TABLE 1 Recommended Concentrations for Individual Quality
Control Standards
Concentration to Attain
Oxygenate
2.0 % mass O 2.7 % mass O 3.5 % mass O
Methanol 4.00 % mass 5.41 % mass
Ethanol 5.76 % mass 7.77 % mass 10.1 % mass
tert-Butanol 9.26 % mass 12.5 % mass
MTBE 11.0 % mass 14.9 % mass
TAME 12.8 % mass 17.2 % mass
DIPE 12.8 % mass 17.2 % mass
ETBE 12.8 % mass 17.2 % mass
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10. Quality Control Standards
10.1 Confirm the proper operation of the instrument each day it is used by analyzing at least one quality control standard of known
oxygenate content for each oxygenate to be determined. These standards should be made up by mass according to Practice D4307
and should be at the expected concentration level for that oxygenate. The recommended quality control standard concentrations
are found in Table 1.
10.2 The individual oxygenate values obtained must agree within 65 % relative of the values in the prepared quality control
standard (for example, MTBE
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