ASTM D5441-98(2008)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 C12 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: 30-Apr-2008
• ICS: 71.080.60 - Alcohols. Ethers
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0L - Gas Chromatography Methods

Relations

• Replaces: ASTM D5441-98(2003)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: 01-May-2008

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
´1
Designation: D5441 − 98(Reapproved 2008)
Standard Test Method for
Analysis of Methyl Tert-Butyl Ether (MTBE) by Gas
Chromatography
This standard is issued under the fixed designation D5441; 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.
´ NOTE—Updated sole source of supply footnotes editorially in May 2008.
1. Scope 2. Referenced Documents
1.1 This test method covers the determination of the purity 2.1 ASTM Standards:
of methyl tert-butyl ether (MTBE) by gas chromatography. It D1364 Test Method for Water in Volatile Solvents (Karl
alsoprovidesaproceduretomeasureimpuritiesinMTBEsuch Fischer Reagent Titration Method)
as C to C olefins, methyl, isopropyl and tert-butyl alcohols, D3700 Practice for Obtaining LPG Samples Using a Float-
4 12
methyl sec-butyl and methyl tert-amyl ethers, acetone, and ing Piston Cylinder
methyl ethyl ketone. Impurities are determined to a minimum D4057 Practice for Manual Sampling of Petroleum and
concentration of 0.02 mass %. Petroleum Products
D4307 Practice for Preparation of Liquid Blends for Use as
1.2 This test method is not applicable to the determination
Analytical Standards
of MTBE in gasoline.
D4626 Practice for Calculation of Gas Chromatographic
1.3 Water cannot be determined by this test method and
Response Factors
must be measured by a procedure such as Test Method D1364
E355 Practice for Gas ChromatographyTerms and Relation-
and the result used to normalize the chromatographic values.
ships
1.4 Amajority of the impurities in MTBE is resolved by the E594 Practice for Testing Flame Ionization Detectors Used
in Gas or Supercritical Fluid Chromatography
test method, however, some co-elution is encountered.
1.5 This test method is inappropriate for impurities that boil
3. Terminology
at temperatures higher than 180°C or for impurities that cause
3.1 Definitions—This test method makes reference to many
poor or no response in a flame ionization detector, such as
common gas chromatographic procedures, terms, and relation-
water.
ships. Detailed definitions of these can be found in Practices
1.6 The values stated in SI (metric) units of measurement
E355 and E594.
arepreferredandusedthroughoutthestandard.Alternateunits,
3.2 Definitions of Terms Specific to This Standard:
in common usage, are also provided to improve clarity and aid
3.2.1 C to C olefins—commonolefinimpuritiesinMTBE
4 12
the user of this test method.
are unreacted feedstock and dimers or trimers of feed such as
1.7 This standard does not purport to address all of the
trimethylpentene or pentamethylheptene.
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to consult and
establish appropriate safety and health practices and deter-
4.1 Arepresentative aliquot of the MTBE product sample is
mine the applicability of regulatory limitations prior to use.
introduced into a gas chromatograph equipped with a methyl
silicone bonded phase fused silica open tubular column.
Helium carrier gas transports the vaporized aliquot through the
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.04.0L on Gas Chromatography Methods. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2008. Published September 2008. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
´1
approved in 1993. Last previous edition approved in 2003 as D5441–98(2003) . Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D5441-98R08E01. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D5441 − 98 (2008)
column where the components are separated by the chromato- maintain analytical integrity. Pressure control devices and
graphic process. Components are sensed by a flame ionization gages must be designed to attain the linear velocity required in
detector as they elute from the column. the column used (for example, if a 150 m column is used, a
pressure of approximately 550 kPa (80 psig) is required). A
4.2 The detector signal is processed by an electronic data
hydrogenflameionizationdetectorwithassociatedgascontrols
acquisition system or integrating computer. Each eluting com-
and electronics, designed for optimum response with open
ponent is identified by comparing its retention time to those
tubular columns, is required.
established by analyzing standards under identical conditions.
7.2 Sample Introduction—Manual or automatic liquid sy-
4.3 The concentration of each component in mass percent is
ringe sample injection to the splitting injector is employed.
determined by normalization of the peak areas after each peak
Devices capable of 0.1 to 0.5 µL injections are suitable. It
area has been corrected by a detector response multiplication
should be noted that inadequate splitter design, or poor
factor. The detector response factors are determined by ana-
injection technique, or both can result in poor resolution.
lyzing prepared standards with concentrations similar to those
Overloadingofthecolumncanalsocauselossofresolutionfor
encountered in the sample.
some components and, since overloaded peaks are skewed,
variation in retention times. Watch for any skewed peaks that
5. Significance and Use
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,
Othercolumnswithequalorgreaterresolvingpowermaybe
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,
7.4.6 Positive and negative sloping baseline correction,
TABLE 1 Typical Operating Conditions 7.4.7 Peak detection sensitivity compensation for narrow
and broad peaks, and
Column Temperature Program
Column length 50 m 100 m 150 m
7.4.8 Non-resolved peaks separated by perpendicular drop
Initial temperature 40°C 50°C 60°C
or tangential skimming as needed.
Initial hold time 13 min 13 min 13 min
Program rate 10°C/min 10°C/min 10°C/min
8. Reagents and Materials
Final temperature 180°C 180°C 180°C
Final hold time 3 min 7 min 20 min
8.1 Carrier Gas, helium, 99.99 % pure. (Warning—
Injector
Temperature 200°C
Compressed gas under high pressure.)
Split ratio 200:1
8.2 Fuel Gas, hydrogen, 99.99 % pure. (Warning—
Sample size 0.1 to 0.5 µL
Detector
Extremely flammable gas under pressure.)
Type flame ionization
Temperature 250°C 8.3 Oxidant, air, oil free. (Warning—Compressed gas un-
Fuel gas hydrogen ('30 mL/min)
der high pressure.)
Oxidizing gas air ('300 mL/min)
Make-up gas nitrogen ('30 mL/min)
Carrier Gas
Petrocol DH series columns from Supelco, Inc., Bellefonte, PA were used to
Type helium
Average linear velocity 20–24 cm/s obtain the retention data and example chromatogram shown in this standard. Other
suitable columns are available commercially.
´1
D5441 − 98 (2008)
8.4 Make-Up Gas, nitrogen, 99.99 % pure. (Warning— 9. Sampling
Compressed gas under high pressure.)
9.1 MTBE can be sampled either in a floating piston
cylinder or into an open container since vapor pressures less
8.5 Reference Standards:
4,5
than 70 kPa (10 psi) are expected.
8.5.1 tert-Amyl methyl ether, (Warning—Flammable
9.1.1 Cylinder Sampling—Refer to Practice D3700 for in-
liquid. Harmful if inhaled.)
structionsontransferringarepresentativesamplefromasource
8.5.2 Butane, (Warning—Flammable liquid. Harmful if
into a floating piston cylinder.Add inert gas to the ballast side
inhaled.)
of the piston to achieve a pressure of 310 kPa (45 psi) above
8.5.3 tert-Butanol, (Warning—Flammable liquid. Harmful
the vapor pressure of the sample.
if inhaled.)
9.1.2 Open Container Sampling—Refer to Practice D4057
5,6
8.5.4 sec-Butyl methyl ether, (Warning—Flammable
for instructions on manual sampling from bulk storage into
liquid. Harmful if inhaled.)
open containers. Stopper container immediately after drawing
5,7
8.5.5 4,4-Dimethyl-2-neopentyl-1-pentene , (Warning—
sample.
Flammable liquid. Harmful if inhaled.)
9.2 Preserve the sample by cooling to approximately 4°C
8.5.6 Isobutylene, (Warning—Flammable liquid. Harmful
and by maintaining that temperature until immediately prior to
if inhaled.)
analysis.
8.5.7 Methanol, (Warning—See Note 1.)
9.3 Transfer an aliquot of the cooled sample into a pre-
NOTE 1—Warning: Toxic Flammable Liquid. Harmful if inhaled or
cooled septum vial, then seal appropriately. Obtain the test
ingested.
specimen for analysis directly from the sealed septum vial, for
5,7
8.5.8 2-Methyl-2-butene, (Warning—Flammable liquid.
either manual or automatic syringe injection.
Harmful if inhaled.)
5,8
8.5.9 Methyl tert-butyl ether, 99 + % pure, (Warning— 10. Preparation of Apparatus
Flammable liquid. Harmful if inhaled.)
10.1 Installandconditioncolumninaccordancewithmanu-
5,7
8.5.10 2,2,4,6,6-Pentamethyl-3-heptene , (Warning—
facturer’s or supplier’s instructions. After conditioning, attach
Flammable liquid. Harmful if inhaled.)
column outlet to flame ionization detector inlet and check for
8.5.11 n-Pentane, (Warning—Flammable liquid. Harmful
leaks throughout the system. When leaks are found, tighten or
if inhaled.)
replace fittings before proceeding.
8.5.12 cis-2-Pentene,(Warning—Flammableliquid.Harm-
10.2 Adjust the carrier gas flow rate so that an average
ful if inhaled.)
linear velocity at the starting temperature of the run is between
8.5.13 trans-2-Pentene (Warning—Flammable liquid.
21 and 24 cm/s, as determined in Eq 1. Flow rate adjustment is
Harmful if inhaled.)
made by raising or lowering the carrier gas pressure (head
8.5.14 2,4,4-Trimethyl-1-pentene, (Warning—Flammable pressure) to the injector. The following starting point pressures
liquid. Harmful if inhaled.)
can be useful to adjust the carrier gas flow:
8.5.15 2,4,4-Trimethyl-2-pentene, (Warning—Flammable
Column length 50 m 100 m 150 m
Starting point pressure, kPa (psig) 262 (38) 275 (40) 552 (80)
liquid. Harmful if inhaled.)
5,9
8.5.16 1 % Contaminant Standard, contains 1.0 % of 10.2.1 Average Linear Gas Velocity:
some of the contaminants in MTBE, (Warning—Flammable
u 5 L/t (1)
ave m
liquid. Harmful if inhaled.)
5,9
where:
8.5.17 0.1 % Contaminant Standard, contains 0.1 % of
L = the length of the column in cm, and
some of the contaminants in MTBE, (Warning—Flammable
t = the retention time in seconds of methane.
m
liquid. Harmful if inhaled.)
10.3 Adjust the operating conditions of the gas chromato-
graph to conform to the list in Table 1. Turn on the detector,
ignite the flame, and allow the system to equilibrate.
The sole source of supply of the apparatus known to the committee at this time
isAldrich Chemical Company, Inc., Milwaukee, WI.A96 % pure sample obtained
10.4 When the method is first set up, ensure that the FID is
from Aldrich was the highest purity found.
not saturated. Plot the peak area versus MTBE concentration
If you are aware of alternative suppliers, please provide this information to
ASTM International Headquarters. Your comments will receive careful consider-
for prepared standards in the concentration range of interest. If
ation at a meeting of the responsible technical committee, which you may attend.
the plot is not linear, increase the split ratio, or use a less
The sole source of supply of the apparatus known to the committee at this time
sensitive detector range, or both.
is Farcham Laboratories, Gainesville, FL.
The sole source of supply of the apparatus known to the committee at this time
is Organic Technologies (formerly Wiley Organics), P.O. Box 640, 1245 S. 6th St.,
11. Column Evaluation and Optimization
Coshocton, OH 43812.
The sole source of supply of the apparatus, HPLC grade MTBE, known to the
11.1 In order to establish that the column/temperature pro-
committee at this time is from Aldrich Chemical Company, Inc., Milwaukee, WI.
gram will perform the required separation, the resolution
The sole source of supply of the apparatus, reference samples that contain only
between cis-2-pentene and tert-butanol and between trans-2-
contaminants boiling above ambient, known to the committee at this time is
Supelco, Inc., Bellefonte, PA. pentene and tert-butanol must be determined. The retention of
´1
D5441 − 98 (2008)
tert-butanol relative to cis- and trans-2-pentene is very tem
...