ASTM D5441-98(2003)e1

Standard Test Method for Analysis of Methyl Tert-Butyl Ether (MTBE) by Gas Chromatography

SIGNIFICANCE AND USE
The presence of impurities in MTBE product can have a deleterious effect upon the value of MTBE as a gasoline additive. Oxygenate and olefin contents are of primary concern. This test method provides a knowledge of the composition of MTBE product. This is useful in the evaluation of process operations control, in the valuation of the product, and for regulatory purposes.  
Open tubular column gas chromatography with a flame ionization detector, used by the test method, is a technique that is sensitive to the contaminants commonly found in MTBE, and a technique that is widely used.
SCOPE
1.1 This test method covers the determination of the purity of methyl tert-butyl ether (MTBE) by gas chromatography. It also provides a procedure to measure impurities in MTBE such as C4 to C 12 olefins, methyl, isopropyl and tert-butyl alcohols, methyl sec-butyl and methyl tert-amyl ethers, acetone, and methyl ethyl ketone. Impurities are determined to a minimum concentration of 0.02 mass %.
1.2 This test method is not applicable to the determination of MTBE in gasoline.
1.3 Water cannot be determined by this test method and must be measured by a procedure such as Test Method D 1364 and the result used to normalize the chromatographic values.
1.4 A majority of the impurities in MTBE is resolved by the test method, however, some co-elution is encountered.
1.5 This test method is inappropriate for impurities that boil at temperatures higher than 180°C or for impurities that cause poor or no response in a flame ionization detector, such as water.
1.6 The values stated in SI (metric) units of measurement are preferred and used throughout the standard. Alternate units, in common usage, are also provided to improve clarity and aid the user of this test method.
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 consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-May-2003
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0L - Gas Chromatography Methods

Relations

• Replaces: ASTM D5441-98 - Standard Test Method for Analysis of Methyl Tert-Butyl Ether (MTBE) by Gas Chromatography
• Effective Date: 10-May-2003
• Replaced By: ASTM D5441-98(2008)e1 - Standard Test Method for Analysis of Methyl Tert-Butyl Ether (MTBE) by Gas Chromatography
• Effective Date: 01-May-2008
• Referred By: ASTM D5983-21 - Standard Specification for Methyl Tertiary-Butyl Ether (MTBE) for Blending With Gasolines for Use as Automotive Spark-Ignition Engine Fuel
• Effective Date: 10-May-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
An American National Standard
e1
Designation:D5441–98 (Reapproved 2003)
Standard Test Method for
Analysis of Methyl Tert-Butyl Ether (MTBE) by Gas
Chromatography
This standard is issued under the fixed designation D 5441; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Warning notes were editorially moved into the standard text in August 2003.
1. Scope D 3700 PracticeforObtainingLPGSamplesUsingFloating
Piston Cylinder
1.1 This test method covers the determination of the purity
D 4057 Practice for Manual Sampling of Petroleum and
of methyl tert-butyl ether (MTBE) by gas chromatography. It
Petroleum Products
also provides a procedure to measure impurities in MTBE such
D 4307 PracticeforPreparationofLiquidBlendsforUseas
as C to C olefins, methyl, isopropyl and tert-butyl alcohols,
4 12
Analytical Standards
methyl sec-butyl and methyl tert-amyl ethers, acetone, and
D 4626 Practice for Calculation of Gas Chromatographic
methyl ethyl ketone. Impurities are determined to a minimum
Response Factors
concentration of 0.02 mass %.
E 355 Practice for Gas Chromatography Terms and Rela-
1.2 This test method is not applicable to the determination
tionships
of MTBE in gasoline.
E 594 Practice for Testing Flame Ionization Detectors Used
1.3 Water cannot be determined by this test method and
in Gas Chromatography
must be measured by a procedure such as Test Method D 1364
and the result used to normalize the chromatographic values.
3. Terminology
1.4 Amajority of the impurities in MTBE is resolved by the
3.1 Definitions:
test method, however, some co-elution is encountered.
3.1.1 This test method makes reference to many common
1.5 This test method is inappropriate for impurities that boil
gas chromatographic procedures, terms, and relationships.
at temperatures higher than 180°C or for impurities that cause
Detailed definitions of these can be found in Practices E 355
poor or no response in a flame ionization detector, such as
and E 594.
water.
3.2 Definitions of Terms Specific to This Standard:
1.6 The values stated in SI (metric) units of measurement
3.2.1 C to C olefins—common olefin impurities in
4 12
are preferred and used throughout the standard.Alternate units,
MTBE are unreacted feedstock and dimers or trimers of feed
in common usage, are also provided to improve clarity and aid
such as trimethylpentene or pentamethylheptene.
the user of this test method.
1.7 This standard does not purport to address all of the
4. Summary of Test Method
safety concerns, if any, associated with its use. It is the
4.1 Arepresentative aliquot of the MTBE product sample is
responsibility of the user of this standard to consult and
introduced into a gas chromatograph equipped with a methyl
establish appropriate safety and health practices and deter-
silicone bonded phase fused silica open tubular column.
mine the applicability of regulatory limitations prior to use.
Helium carrier gas transports the vaporized aliquot through the
2. Referenced Documents column where the components are separated by the chromato-
graphic process. Components are sensed by a flame ionization
2.1 ASTM Standards:
detector as they elute from the column.
D 1364 Test Method for Water in Volatile Solvents (Karl
2 4.2 The detector signal is processed by an electronic data
Fischer Reagent Titration Method)
acquisition system or integrating computer. Each eluting com-
ponent is identified by comparing its retention time to those
This test method is under the jurisdiction of ASTM Committee D02 on
established by analyzing standards under identical conditions.
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.04 on Hydrocarbon Analysis.
Current edition approved May 10, 2003. Published August 2003. Originally
approved in 1993. Last previous edition approved in 1998 as D 5441–98. Annual Book of ASTM Standards, Vol 05.02.
2 4
Annual Book of ASTM Standards, Vol 06.04. Annual Book of ASTM Standards, Vol 03.06.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D5441–98 (2003)
4.3 The concentration of each component in mass percent is 7.2 Sample Introduction—Manual or automatic liquid sy-
determined by normalization of the peak areas after each peak ringe sample injection to the splitting injector is employed.
area has been corrected by a detector response multiplication Devices capable of 0.1 to 0.5 µL injections are suitable. It
factor. The detector response factors are determined by ana- should be noted that inadequate splitter design, or poor
lyzing prepared standards with concentrations similar to those injection technique, or both can result in poor resolution.
encountered in the sample. Overloadingofthecolumncanalsocauselossofresolutionfor
some components and, since overloaded peaks are skewed,
5. Significance and Use variation in retention times. Watch for any skewed peaks that
indicate overloading during column evaluation. Observe the
5.1 The presence of impurities in MTBE product can have a
component size and where possible, avoid conditions leading
deleterious effect upon the value of MTBE as a gasoline
to this problem during the analyses.
additive. Oxygenate and olefin contents are of primary con-
7.3 Open Tubular Column—This test method utilizes a
cern. This test method provides a knowledge of the composi-
fused silica open tubular column with non-polar methyl sili-
tion of MTBE product. This is useful in the evaluation of
cone bonded (cross-linked) phase internal coating such as one
process operations control, in the valuation of the product, and
of the following:
for regulatory purposes.
Column length 50 m 100 m 150 m
5.2 Open tubular column gas chromatography with a flame
Film thickness 0.5 µm 0.5 µm 1.0 µm
ionization detector, used by the test method, is a technique that
Internal diameter 0.20 mm 0.25 mm 0.25 mm
is sensitive to the contaminants commonly found in MTBE,
Other columns with equal or greater resolving power may be
and a technique that is widely used.
used. A minimum resolution between trans-2-pentene and
tert-butanol, and between cis-2-pentene and tert-butanol of 1.3
6. Interferences
is required. The 150 m column is expected to decrease the
6.1 Cyclopentane and 2,3-dimethylbutane have been ob-
likelihood of co–elution of impurities.
served to co-elute with MTBE. However, these are not com-
7.4 Electronic Data Acquisition System—Any data acquisi-
monly found impurities in MTBE.
tion and integration device used for quantification of these
analyses must meet or exceed these minimum requirements:
7. Apparatus
7.4.1 Capacity for at least 50 peaks per analysis,
7.1 Gas Chromatograph—Instrumentation capable of oper-
7.4.2 Normalized area percent calculations with response
ating at the conditions listed in Table 1. A heated flash
factors,
vaporizing injector designed to provide a linear sample split
7.4.3 Identification of individual components based on re-
injection (that is, 200:1) is required for proper sample intro-
tention time,
duction. Carrier gas controls must be of adequate precision to
7.4.4 Noise and spike rejection capability,
provide reproducible column flows and split ratios in order to
7.4.5 Sampling rate for fast (<1 s) peaks,
maintain analytical integrity. Pressure control devices and
7.4.6 Positive and negative sloping baseline correction,
gages must be designed to attain the linear velocity required in
7.4.7 Peak detection sensitivity compensation for narrow
the column used (for example, if a 150 m column is used, a
and broad peaks, and
pressure of approximately 550 kPa (80 psig) is required). A
7.4.8 Non-resolved peaks separated by perpendicular drop
hydrogenflameionizationdetectorwithassociatedgascontrols
or tangential skimming as needed.
and electronics, designed for optimum response with open
tubular columns, is required.
8. Reagents and Materials
8.1 Carrier Gas, helium, 99.99 % pure. (Warning—
Compressed gas under high pressure.)
TABLE 1 Typical Operating Conditions
8.2 Fuel Gas, hydrogen, 99.99 % pure. (Warning—
Column Temperature Program
Extremely flammable gas under pressure.)
Column length 50 m 100 m 150 m
8.3 Oxidant, air, oil free. (Warning—Compressed gas un-
Initial temperature 40°C 50°C 60°C
Initial hold time 13 min 13 min 13 min der high pressure.)
Program rate 10°C/min 10°C/min 10°C/min
8.4 Make-Up Gas, nitrogen, 99.99 % pure. (Warning—
Final temperature 180°C 180°C 180°C
Compressed gas under high pressure.)
Final hold time 3 min 7 min 20 min
Injector
8.5 Reference Standards:
Temperature 200°C
8.5.1 tert-Amyl methyl ether, (Warning—Flammable liq-
Split ratio 200:1
uid. Harmful if inhaled.)
Sample size 0.1 to 0.5 µL
Detector
Type flame ionization
Temperature 250°C
Fuel gas hydrogen ('30 mL/min)
Petrocol DH series columns available from Supelco, Inc., Bellefonte, PA, USA
Oxidizing gas air ('300 mL/min)
have proven satisfactory for this test method and were used to obtain the retention
Make-up gas nitrogen ('30 mL/min)
data and example chromatogram shown. Also, HP-PONA columns available from
Carrier Gas
Hewlett Packard Company, Wilmington, DE, have been found satisfactory.
Type helium
Average linear velocity 20–24 cm/s A96 % pure sample obtained fromAldrich Chemical Company, Inc., Milwau-
kee, WI was the highest purity found.
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D5441–98 (2003)
8.5.2 Butane,(Warning—Flammable liquid. Harmful if 9.3 Transfer an aliquot of the cooled sample into a pre-
inhaled.) cooled septum vial, then seal appropriately. Obtain the test
8.5.3 tert-Butanol,(Warning—Flammable liquid. Harmful specimen for analysis directly from the sealed septum vial, for
if inhaled.) either manual or automatic syringe injection.
8.5.4 sec-Butyl methyl ether, (Warning—Flammable liq-
uid. Harmful if inhaled.) 10. Preparation of Apparatus
8.5.5 4,4-Dimethyl-2-neopentyl-1-pentene, (Warning—
10.1 Install and condition column in accordance with manu-
Flammable liquid. Harmful if inhaled.)
facturer’s or supplier’s instructions. After conditioning, attach
8.5.6 Isobutylene,(Warning—Flammable liquid. Harmful
column outlet to flame ionization detector inlet and check for
if inhaled.)
leaks throughout the system. When leaks are found, tighten or
8.5.7 Methanol,(Warning—See Note 1.)
replace fittings before proceeding.
10.2 Adjust the carrier gas flow rate so that an average
NOTE 1—Warning: Toxic Flammable Liquid. Harmful if inhaled or
ingested. linear velocity at the starting temperature of the run is between
21 and 24 cm/s, as determined in Eq 1. Flow rate adjustment is
8.5.8 2-Methyl-2-butene, (Warning—Flammable liquid.
made by raising or lowering the carrier gas pressure (head
Harmful if inhaled.)
pressure) to the injector. The following starting point pressures
8.5.9 Methyl tert-butyl ether, 99 + % pure, (Warning—
can be useful to adjust the carrier gas flow:
Flammable liquid. Harmful if inhaled.)
Column length 50 m 100 m 150 m
8.5.10 2,2,4,6,6-Pentamethyl-3-heptene, (Warning—
Starting point pressure, kPa (psig) 262 (38) 275 (40) 552 (80)
Flammable liquid. Harmful if inhaled.)
8.5.11 n-Pentane,(Warning—Flammable liquid. Harmful 10.2.1 Average Linear Gas Velocity:
if inhaled.)
u 5 L/t (1)
ave m
8.5.12 cis-2-Pentene,(Warning—Flammableliquid.Harm-
where:
ful if inhaled.)
L = the length of the column in cm, and
8.5.13 trans-2-Pentene (Warning—Flammable liquid.
t = the retention time in seconds of methane.
m
Harmful if inhaled.)
10.3 Adjust the operating conditions of the gas chromato-
8.5.14 2,4,4-Trimethyl-1-pentene,(Warning—Flammable
graph to conform to the list in Table 1. Turn on the detector,
liquid. Harmful if inhaled.)
ignite the flame, and allow the system to equilibrate.
8.5.15 2,4,4-Trimethyl-2-pentene,(Warning—Flammable
10.4 When the method is first set up, ensure that the FID is
liquid. Harmful if inhaled.)
not saturated. Plot the peak area versus MTBE concentration
8.5.16 1 % Contaminant Standard, contains 1.0 % of
for prepared standards in the concentration range of interest. If
some of the contaminants in MTBE, (Warning—Flammable
the plot is not linear, increase the split ratio, or use a less
liquid. Harmful if inhaled.)
sensitive detector range, or both.
8.5.17 0.1 % Contaminant Standard, contains 0.1 % of
some of the contaminants in MTBE, (Warning—Flammable
11. Column Evaluation and Optimization
liquid. Harmful if inhaled.)
11.1 In order to establish that the column/temperature pro-
9. Sampling
gram will perform the required separation, the resolution
9.1 MTBE can be sampled either in a floating piston
between cis-2-pentene and tert-butanol and between trans-2-
cylinder or into an open container since vapor pressures less
pentene and tert-butanol must be determined. The retention of
than 70 kPa (10 psi) are expected.
tert-butanol relative to cis- and trans-2-pentene is very tem-
9.1.1 Cylinder Sampling—Refer to Practice D 3700 for
perature dependent. The order of elution of cis-2-pentene and
instructions on transferring a representative sample from a
tert-butanol reverses at subambient temperature. A column
source into a floating piston cylinder. Add inert gas to the
which does not resolve these components after adjusting
ballast side of the piston to achieve a pressure of 310 kPa (45
operating conditions is unsuitable.
psi) above the vapor pressure of the sample.
11.2 Analyze a standard mixture that contains approxi-
9.1.2 Open Container Sampling—Refer to Practice D 4057
mately 1 % each of tert-butanol, cis-2-pentene, and trans-2-
for instructions on manual sampling from bulk storage into
pentene in MTBE by the procedure in Section 13. Calculate
open containers. Stopper container immediately after drawing
resolution (R) between tert-butanol and cis-2-pentene and
sample.
between trans-2-pentene and tert-butanol using Eq 2. Both
9.2 Preserve the sample by cooling to approximately 4°C
resolutions must be at least 1.3.
and by maintaining that temperature until immediately prior to
2~t 2 t !
B A
analysis.
R 5 (2)
1.699~W 1 W !
A B
Available from Farcham Laboratories, Gainesville, FL
where:
Available from Wiley Organics, Coshocton, OH.
HPLCgradeMTBEfromAldrichChemicalCompany,Inc.,Milwaukee,WIhas
R = resolution,
been found to be satisfactory.
t = retention time Component A,
A
These reference samples, that contain only contaminants boiling above
t = retention time Component B,
B
ambient, are available from Supelco, Inc., Bellefonte, PA.
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D5441–9
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