ASTM D4815-22

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: D4815 − 15b (Reapproved 2019) D4815 − 22
Standard Test Method for
Determination of MTBE, ETBE, TAME, DIPE, tertiary-Amyl
Alcohol and C to C Alcohols in Gasoline by Gas
1 4
Chromatography
This standard is issued under the fixed designation D4815; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope Scope*
1.1 This test method covers the determination of ethers and alcohols in gasolines by gas chromatography. Specific compounds
determined are methyl tert-butylether (MTBE), ethyl tert-butylether (ETBE), tert-amylmethylether (TAME), diisopropylether
(DIPE), methanol, ethanol, isopropanol, n-propanol, isobutanol, tert-butanol, sec-butanol, n-butanol, and tert-pentanol (tert-
amylalcohol).
1.2 Individual ethers are determined from 0.20 % to 20.0 % by mass. Individual alcohols are determined from 0.20 % to 12.0 %
by mass. Equations used to convert to mass %mass percent oxygen and to volume %volume percent of individual compounds are
provided. At concentrations <0.20 % by mass, it is possible that hydrocarbons may interfere with several ethers and alcohols. The
reporting limit of 0.20 % by mass was tested for gasolines containing a maximum of 10 % by volume olefins. It may be possible
that for gasolines containing >10 % by volume olefins, the interference may be >0.20 % by mass. Annex A1 gives a chromatogram
showing the interference observed with a gasoline containing 10 % by volume olefins.
1.3 This test method includes a relative bias correlation for ethanol in spark-ignition engine fuels for the U.S. EPA regulations
reporting based on Practice D6708 accuracy assessment between Test Method D4815 and Test Method D5599 as a possible Test
Method D4815 alternative to Test Method D5599. The Practice D6708 derived correlation equation is only applicable for ethanol
in fuels in the concentration range from 2.28 % to 14.42 % by mass as measured by Test Method D4815. The applicable Test
Method D5599 range for ethanol is from 2.16 % to 14.39 % by mass as reported by Test Method D5599.
1.4 Alcohol-based fuels, such as M-85 and E-85, MTBE product, ethanol product, and denatured alcohol, are specifically excluded
from this test method. The methanol content of M-85 fuel is considered beyond the operating range of the system.
1.5 Benzene, while detected, cannot be quantified using this test method and mustshall be analyzed by alternate methodology (see
Test Method D3606).
1.6 The values stated in SI units are to be regarded as standard. Alternate units, in common usage, are also provided to increase
clarity and aid the users of this test method.
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 Gas Chromatography Methods.
Current edition approved Dec. 1, 2019April 1, 2022. Published December 2019April 2022. Originally approved in 1989. Last previous edition approved in 20152019 as
D4815 – 15b.D4815 – 15b (2019). DOI: 10.1520/D4815-15BR19.10.1520/D4815-22.
*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
D4815 − 22
1.7 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.
1.8 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
3 3
D1744 Test Method for Determination of Water in Liquid Petroleum Products by Karl Fischer Reagent (Withdrawn 2016)
D3606 Test Method for Determination of Benzene and Toluene in Spark Ignition Fuels by Gas Chromatography
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
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D4420 Test Method for Determination of Aromatics in Finished Gasoline by Gas Chromatography (Withdrawn 2004)
D5599 Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame
Ionization Detection
D5842 Practice for Sampling and Handling of Fuels for Volatility Measurement
D6304 Test Method for Determination of Water in Petroleum Products, Lubricating Oils, and Additives by Coulometric Karl
Fischer Titration
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
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 low volume connector—a special union for connecting two lengths of tubing 1.6 mm inside diameter and smaller. Sometimes
this is referred to as zero dead volume union.
3.2.2 oxygenate—any oxygen-containing organic compound that can be used as a fuel or fuel supplement, for example, various
alcohols and ethers.
3.2.3 split ratio—in capillary gas chromatography, the ratio of the total flow of carrier gas to the sample inlet versus the flow of
the carrier gas to the capillary column, expressed by
split ratio 5 S1C /C (1)
~ !
where:
S = flow rate at the splitter vent, and
C = flow rate at the column outlet.
3.2.4 tert-amyl alcohol—tert-pentanol.
3.3 Acronyms:
3.3.1 DIPE—diisopropylether.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
D4815 − 22
3.3.2 ETBE—ethyl tert-butylether.
3.3.3 MTBE—methyl tert-butylether.
3.3.4 TAME—tert-amyl methylether.
3.3.5 TCEP—1,2,3-tris-2-cyanoethoxypropane—a gas chromatographic liquid phase.
3.3.6 WCOT—a type of capillary gas chromatographic column prepared by coating the inside of the capillary with a thin film of
stationary phase.
4. Summary of Test Method
4.1 An appropriate internal standard, such as 1,2-dimethoxyethane (ethylene glycol dimethyl ether), is added to the sample, which
is then introduced into a gas chromatograph equipped with two columns and a column switching valve. The sample first passes
onto a polar TCEP column, which elutes lighter hydrocarbons to vent and retains the oxygenated and heavier hydrocarbons.
4.2 After methylcyclopentane, but before DIPE and MTBE elute from the polar column, the valve is switched to backflush the
oxygenates onto a WCOT nonpolar column. The alcohols and ethers elute from the nonpolar column in boiling point order, before
elution of any major hydrocarbon constituents.
4.3 After benzene and TAME elute from the nonpolar column, the column switching valve is switched back to its original position
to backflush the heavy hydrocarbons.
4.4 The eluted components are detected by a flame ionization or thermal conductivity detector. The detector response, proportional
to the component concentration, is recorded; the peak areas are measured; and the concentration of each component is calculated
with reference to the internal standard.
5. Significance and Use
5.1 Ethers, alcohols, and other oxygenates can be added to gasoline to increase octane number and to reduce emissions. Type and
concentration of various oxygenates are specified and regulated to ensure acceptable commercial gasoline quality. Drivability,
vapor pressure, phase separation, exhaust, and evaporative emissions are some of the concerns associated with oxygenated fuels.
5.2 This test method is applicable to both quality control in the production of gasoline and for the determination of deliberate or
extraneous oxygenate additions or contamination.
6. Apparatus
6.1 Chromatograph—While any gas chromatographic system, which is capable of adequately resolving the individual ethers and
alcohols that are presented in Table 1, can be used for these analyses, a gas chromatographic instrument, which can be operated
at the conditions given in Table 2 and has a column switching and backflushing system equivalent to Fig. 1, has been found
acceptable. Carrier gas flow controllers shall be capable of precise control where the required flow rates are low (see Table 2).
Pressure control devices and gages shall be capable of precise control for the typical pressures required.
6.1.1 Detector—A thermal conductivity detector or flame ionization detector can be used. The system shall have sufficient
sensitivity and stability to obtain a recorder deflection of at least 2 mm at a signal-to-noise ratio of at least 5 to 1 for 0.005 % by
volume concentration of an oxygenate.
6.1.2 Switching and Backflushing Valve—A valve, to be located within the gas chromatographic column oven, capable of
performing the functions described in Section 11 and illustrated in Fig. 1. The valve shall be of low volume design and not
contribute significantly to chromatographic deterioration.
6.1.2.1 Valco Model No. A 4C10WP, 1.6 mm ( ⁄16 in.) fittings. This particular valve was used in the majority of the analyses used
for the development of Section 15.
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TABLE 1 Pertinent Physical Constants and Retention
Characteristics for TCEP/WCOT Column Set Conditions
as in Table 2
Relative Retention
Relative
Time
Retention Molecular Density at
Component
Time, Min. Mass 15.56/
(MTBE = (DME =
15.5 6 °C
1.00) 1.00)
Water 2.90 0.58 0.43 18.0 1.000
Methanol 3.15 0.63 0.46 32.0 0.7963
Ethanol 3.48 0.69 0.51 46.1 0.7939
Isopropanol 3.83 0.76 0.56 60.1 0.7899
tert-Butanol 4.15 0.82 0.61 74.1 0.7922
n-Propanol 4.56 0.90 0.67 60.1 0.8080
MTBE 5.04 1.00 0.74 88.2 0.7460
sec-Butanol 5.36 1.06 0.79 74.1 0.8114
DIPE 5.76 1.14 0.85 102.2 0.7282
Isobutanol 6.00 1.19 0.88 74.1 0.8058
ETBE 6.20 1.23 0.91 102.2 0.7452
tert-Pentanol 6.43 1.28 0.95 88.1 0.8170
1,2-Dimethoxyethane 6.80 1.35 1.00 90.1 0.8720
(DME)
n-Butanol 7.04 1.40 1.04 74.1 0.8137
TAME 8.17 1.62 1.20 102.2 0.7758
TABLE 2 Chromatographic Operation Conditions
Temperatures Flows, mL/min Carrier Gas: Helium
A
Column Oven 60 to injector 75 Sample size, μL 1.0–3.0
Injector, °C 200 Column 5 Split ratio 15:1
Detector—TCD, °C 200 Auxiliary 3 Backflush, min 0.2–0.3
—FID, °C 250 Makeup 18 Valve reset time 8–10 min
Valve °C 60 Total Analysis time 18–20 min
A
Sample size mustshall be adjusted so that alcohols in the range of 0.1 % to
12.0 % by mass and ethers in the range of 0.1 % to 20.0 % by mass are eluted
from the column and measured linearly at the detector. A sample size of 1.0 μL has
been introduced in most cases.
6.1.2.2 Valco Model No. C10W, 0.8 mm ( ⁄32 in.) fittings. This valve is recommended for use with columns of 0.32 mm inside
diameter and smaller.
6.1.2.3 Some gas chromatographs are equipped with an auxiliary oven, which can be used to contain the valve and polar column.
In such a configuration, the nonpolar column is located in the main oven and the temperature can be adjusted for optimum
oxygenates resolution.
6.1.3 An automatic valve switching device mustshall be used to ensure repeatable switching times. Such a device should be
synchronized with injection and data collection times.
6.1.4 Injection System—The chromatograph should be equipped with a splitting-type inlet device if capillary columns or flame
ionization detection are used. Split injection is necessary to maintain the actual chromatographed sample size within the limits of
column and detector optimum efficiency and linearity.
6.1.4.1 Some gas chromatographs are equipped with on-column injectors and autosamplers, which can inject small samples sizes.
Such injection systems can be used provided that sample size is within the limit of the column and detectors optimum efficiency
and linearity.
6.1.4.2 Microlitre syringes, automatic syringe injectors, and liquid sampling valves have been used successfully for introducing
representative samples into the gas chromatographic inlet.
6.2 Data Presentation or Calculation, or Both:
6.2.1 Recorder—A recording potentiometer or equivalent with a full-scale deflection of 5 mV or less can be used to monitor
detector signal. Full-scale response time should be 1 s or less with sufficient sensitivity and stability to meet the requirements of
6.1.1.
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NOTE 1—Detector B is optional and used to simplify setting cut times.
FIG. 1 AnalysisAnalyses of Oxygenates in Gasoline Schematic of Chromatographic SystemExample Chromatogram Showing Oxygen-
ates
6.2.2 Integrator or Computer—Means shall be provided for determining the detector response. Peak heights or areas can be
measured by computer, electronic integration, or manual techniques.
6.3 Columns, Two as Follows:
6.3.1 Polar Column—This column performs a preseparation of the oxygenates from volatile hydrocarbons in the same boiling
point range. The oxygenates and remaining hydrocarbons are backflushed onto the nonpolar column in 6.3.2. Any column with
equivalent or better chromatographic efficiency and selectivity to that described in 6.3.1.1 can be used. The column shall perform
at the same temperature as required for the column in 6.3.2, except if located in a separate auxiliary oven as in 6.1.2.3.
6.3.1.1 TCEP Micro-Packed Column, 560 mm (22 in.) by 1.6 mm ( ⁄16 in.) outside diameter by 0.76 mm (0.030 in.) inside
diameter stainless steel tube packed with 0.14 g to 0.15 g of 20 % (mass/mass) TCEP on 80/100 mesh Chromosorb P(AW). This
column was used in the cooperative study to provide the precision and bias data referred to in Section 15.
6.3.2 Nonpolar (Analytical) Column—Any column with equivalent or better chromatographic efficiency and selectivity to that
described in 6.3.2.1 and illustrated in Fig. 2 can be used.
6.3.2.1 WCOT Methyl Silicone Column, 30 m (1181 in.) long by 0.53 mm (0.021 in.) inside diameter fused silica WCOT column
with a 2.6 μm film thickness of cross-linked methyl siloxane. This column was used in the cooperative study to provide the
precision and bias data referred to in Section 15.
7. Reagents and Materials
7.1 Carrier Gas—Carrier gas appropriate to the type of detector used. Helium has been used successfully. The minimum purity
of the carrier gas used mustshall be 99.95 mol %.
7.2 Standards for Calibration and Identification—Standards of all components to be analyzed and the internal standard 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. (Warning—These materials are flammable and can be
harmful or fatal if ingested or inhaled.)
D4815 − 22
FIG. 2 AnalysesAnalysis of Oxygenates in Gasoline Example Chromatogram Showing OxygenatesSchematic of Chromatographic Sys-
tem
7.3 Methylene Chloride, used for column preparation, reagent grade, free of nonvolatile residue. (Warning—Harmful if inhaled.
High concentrations may cause unconsciousness or death.)
8. Preparation of Column Packings
8.1 TCEP Column Packing:
8.1.1 Any satisfactory method used in the practice of the art that will produce a column capable of retaining the C1 to C4 alcohols
and MTBE, ETBE, DIPE, and TAME from components of the same boiling point range in a gasoline sample. The following
procedure has been used successfully.
8.1.2 Completely dissolve 10 g of TCEP in 100 mL of methylene chloride. Next add 40 g of 80/100 mesh Chromosorb P(AW) to
the TCEP solution. Quickly transfer this mixture to a drying dish, in a fume hood, without scraping any of the residual packing
from the sides of the container. Constantly, but gently, stir the packing until all of the solvent has evaporated. This column packing
can be used immediately to prepare the TCEP column.
9. Sampling
9.1 Every effort should be made to ensure that the sample is representative of the fuel source from which it is taken. Follow the
recommendations of Practice D4057, or its equivalent, when obtaining samples from bulk storage or pipelines.
9.1.1 Follow the recommendations of Practice D4057, or its equivalent when obtaining manual samples from bulk storage or
pipelines.
9.1.2 Follow the recommendations of Practice D4177 for automatic sample from bulk storage or pipelines.
9.1.3 Follow the recommendations of Practice D5842 for sampling fuels for volatility measurements.
9.2 Upon receipt in the laboratory, chill the sample in its original container to 0 °C to 5 °C (32 °F to 40 °F) before any subsampling
is performed.
9.3 If necessary, transfer the chilled sample to a vapor tight container and store at 0 °C to 5 °C (32 °F to 40 °F) until needed for
analysis.
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10. Preparation of Micro-Packed TCEP Column
10.1 Wash a straight 560 mm length of 1.6 mm outside diameter (0.76 mm inside diameter) stainless steel tubing with methanol
and dry with compressed nitrogen.
10.2 Insert six to twelve strands of silvered wire, a small mesh screen, or stainless steel frit inside one end of the tube. Slowly
add 0.14 g to 0.15 g of packing material to the column and gently vibrate to settle the packing inside the column. When strands
of wire are used to retain the packing material inside the column, leave 6.0 mm (0.25 in.) of space at the top of the column.
10.3 Column Conditioning—Both the TCEP and WCOT columns are to be briefly conditioned before use. Connect the columns
to the valve (see 11.1) in the chromatographic oven. Adjust the carrier gas flows as in 11.3 and place the valve in the RESET
position. After several minutes, increase the column oven temperature to 120 °C and maintain these conditions for 5 min to 10 min.
Cool the columns below 60 °C before shutting off the carrier flow.
11. Preparation of Apparatus and Establishment of Conditions
11.1 Assembly—Connect the WCOT column to the valve system using low volume connectors and narrow bore tubing. It is
important to minimize the volume of the chromatographic system that comes in contact with the sample; otherwise, peak
broadening will occur.
11.2 Adjust the operating conditions to those listed in Table 2, but do not turn on the detector circuits. Check the system for leaks
before proceeding further.
11.2.1 If different polar and nonpolar columns or capillary columns of smaller ID, or both, are used it can be necessary to use
different optimum flows and temperatures.
11.3 Flow Rate Adjustment:
11.3.1 Attach a flow measuring device to the column vent with the valve in the RESET position and adjust the pressure to the
injection port to give 5.0 mL ⁄min flow (14 psig). Soap bubble flow meters are suitable.
11.3.2 Attach a flow measuring device to the split injector vent and adjust the flow from the split vent using the A flow controller
to give a flow of 70 mL ⁄min. Recheck the column vent flow set in 11.3.1 and adjust if necessary.
11.3.3 Switch the valve to the BACKFLUSH position and adjust the variable restrictor to give the same column vent flow set in
11.3.1. This is necessary to minimize flow changes when the valve is switched.
11.3.4 Switch the valve to the inject position RESET and adjust the B flow controller to give a flow of 3.0 mL ⁄min to 3.2 mL ⁄min
at the detector exit. When required for the particular instrumentation used, add makeup flow or TCD switching flow to give a total
of 21 mL ⁄min at the detector exit.
11.4 When a thermal conductivity detector is used, turn on the filament current and allow the detector to equilibrate. When a flame
ionization detector is used, set the hydrogen and air flows and ignite the flame.
11.5 Determine the Time to Backflush—The time to backflush will vary slightly for each column system and mustshall be
determined experimentally as follows. The start time of the integrator and valve timer mustshall be synchronized with the injection
to accurately reproduce the backflush time.
11.5.1 Initially assume a valve BACKFLUSH time of 0.23 min. With the valve RESET, inject 1 μL to 3 μL of a blend containing
at least 0.5 % or greater oxygenates (see 7.3), and simultaneously begin timing the analysis. At 0.23 min, rotate the valve to the
BACKFLUSH position and leave it there until the complete elution of TAME is realized. Record this time as the RESET time,
which is the time at which the valve is returned to the RESET position. When all of the remaining hydrocarbons are backflushed,
the signal will return to a stable baseline and the system is ready for another analysis. The chromatogram should appear similar
to the one illustrated in Fig. 21.
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11.5.1.1 Ensure that the BACKFLUSH time is sufficient to quantitatively transfer the higher concentrations of the ethers,
specifically MTBE, into the nonpolar column.
11.5.2 It is necessary to optimize the valve BACKFLUSH time by analyzing a standard blend containing oxygenates. The correct
BACKFLUSH time is determined experimentally by using valve switching times between 0.20 min and 0.35 min. When the valve
is switched too soon, C5 and lighter hydrocarbons are backflushed and are co-eluted in the C4 alcohol section of the chromatogram.
When the valve BACKFLUSH is switched too late, part or all of the ether component (MTBE, ETBE, or TAME) is vented,
resulting in an incorrect ether measurement. DIPE is the first component to be vented, followed by ETBE, MTBE, and TAME,
respectively.
11.5.2.1 DIPE may require a BACKFLUSH time slightly shorter than the other ethers. The system may require reoptimization if
the analysis of DIPE is required.
11.5.3 To facilitate setting BACKFLUSH time, the column vent in Fig. 1 can be connected to a second detector (TCD or FID),
as described in Test Method D4420, and used to set BACKFLUSH TIME based on the oxygenates standard containing the ethers
of interest.
12. Calibration and Standardization
12.1 Identification—Determine the retention time of each component either by injecting small amounts separately, in known
mixtures, or by comparing the relative retention times with those in Table 1.
12.1.1 To ensure minimum interference from hydrocarbons, it is strongly recommended that a fuel devoid of oxygenates be
chromatographed to determine the level of any hydrocarbon interference.
12.2 Preparation of Calibration Samples—Prepare multi-component calibration standards of the oxygenates and concentration
ranges of interest, by mass, in accordance with Practice D4307.
12.2.1 For each oxygenate, prepare a minimum of five
...