ASTM D5599-00(2005)
(Test Method)Standard Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection
Standard Test Method for Determination of Oxygenates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection
SIGNIFICANCE AND USE
In gasoline blending, the determination of organic oxygenated compounds is important. Alcohols, ethers, and other oxygenates are added to gasoline to increase the octane number and to reduce tailpipe emissions of carbon monoxide. They must be added in the proper concentration and ratios to meet regulatory limitations and to avoid phase separation and problems with engine performance or efficiency.
This test method provides sufficient oxygen-to-hydro-carbon selectivity and sensitivity to allow determination of oxygenates in gasoline samples without interference from the bulk hydrocarbon matrix.
SCOPE
1.1 This test method covers a gas chromatographic procedure for the quantitative determination of organic oxygenated compounds in gasoline having a final boiling point not greater than 220°C and oxygenates having a boiling point limit of 130°C. It is applicable when oxygenates are present in the 0.1 to 20 % by mass range.
1.2 This test method is intended to determine the mass concentration of each oxygenate compound present in a gasoline. This requires knowledge of the identity of each oxygenate being determined (for calibration purposes). However, the oxygen-selective detector used in this test method exhibits a response that is proportional to the mass of oxygen. It is, therefore, possible to determine the mass concentration of oxygen contributed by any oxygenate compound in the sample, whether or not it is identified. Total oxygen content in a gasoline may be determined from the summation of the accurately determined individual oxygenated compounds. The summed area of other, uncalibrated or unknown oxygenated compounds present, may be converted to a mass concentration of oxygen and summed with the oxygen concentration of the known oxygenated compounds.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D5599–00 (Reapproved 2005)
Standard Test Method for
Determination of Oxygenates in Gasoline by Gas
Chromatography and Oxygen Selective Flame Ionization
Detection
This standard is issued under the fixed designation D5599; 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 2. Referenced Documents
1.1 This test method covers a gas chromatographic proce- 2.1 ASTM Standards:
dure for the quantitative determination of organic oxygenated D1744 Test Method for Determination of Water in Liquid
compounds in gasoline having a final boiling point not greater Petroleum Products by Karl Fischer Reagent
than 220°C and oxygenates having a boiling point limit of D4175 Terminology Relating to Petroleum, Petroleum
130°C. It is applicable when oxygenates are present in the 0.1 Products, and Lubricants
to 20 % by mass range. D4307 Practice for Preparation of Liquid Blends for Use as
1.2 This test method is intended to determine the mass Analytical Standards
concentration of each oxygenate compound present in a gaso- E594 Practice for Testing Flame Ionization Detectors Used
line.This requires knowledge of the identity of each oxygenate in Gas or Supercritical Fluid Chromatography
being determined (for calibration purposes). However, the E1064 Test Method for Water in Organic Liquids by Cou-
oxygen-selective detector used in this test method exhibits a lometric Karl Fischer Titration
response that is proportional to the mass of oxygen.Itis, E1510 Practice for Installing Fused Silica Open Tubular
therefore, possible to determine the mass concentration of Capillary Columns in Gas Chromatographs
oxygen contributed by any oxygenate compound in the sample,
3. Terminology
whether or not it is identified. Total oxygen content in a
3.1 Definitions:
gasoline may be determined from the summation of the
accurately determined individual oxygenated compounds. The 3.1.1 independent reference standards—calibration samples
summed area of other, uncalibrated or unknown oxygenated of the oxygenates which are purchased or prepared from
materials independent of the quality control check standards
compounds present, may be converted to a mass concentration
of oxygen and summed with the oxygen concentration of the and used for intralaboratory accuracy.
3.1.2 oxygenate, n—an oxygen-containing compound, such
known oxygenated compounds.
1.3 The values stated in SI units are to be regarded as as an alcohol or ether, which may be used as a fuel or fuel
supplement. D4175
standard. No other units of measurement are included in this
standard. 3.1.3 quality control check standards—calibration samples
of the oxygenates for intralaboratory repeatability.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Test Method
responsibility of the user of this standard to establish appro-
4.1 An internal standard of a noninterfering oxygenate, for
priate safety and health practices and determine the applica-
example, 1,2-dimethoxyethane (ethylene glycol dimethyl
bility of regulatory limitations prior to use.
ether) is added in quantitative proportion to the gasoline
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee For referenced ASTM standards, visit the ASTM website, www.astm.org, or
D02.04.0L on Gas Chromatography Methods. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Nov. 1, 2005. Published November 2005. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 1994. Last previous edition approved in 2000 as D5599 – 00. DOI: the ASTM website.
10.1520/D5599-00R05. Withdrawn.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5599–00 (2005)
sample. A representative aliquot of the sample and internal or before the FID and is operated in the range from 350 to
standard is injected into a gas chromatograph equipped with a 450°C, depending on the instrument’s manufacturer.
capillary column operated to ensure separation of the oxygen-
NOTE 2—Gasolines with high sulfur content may cause a loss in
ates. Hydrocarbons and oxygenates are eluted from the col-
detector sensitivity thereby limiting the number of samples that can be
umn, but only oxygenates are detected with the oxygen-
analyzed before the catalyst needs replacement.
selective flame ionization detector (OFID).Adiscussion of this
7. Apparatus
detector is presented in Section 6.
4.2 Calibration mixtures are used for determining the reten- 7.1 Gas Chromatograph—Any gas chromatograph can be
tion times and relative mass response factors of the oxygenates
used having the following performance characteristics:
of interest. Suggested calibrant materials are listed in 8.2. 7.1.1 Column Temperature Programmer—The chromato-
4.3 The peak area of each oxygenate in the gasoline is graph must be capable of reproducible linear temperature
measured relative to the peak area of the internal standard. A programming over a range sufficient for separation of the
quadratic least-squares fit of the calibrated data of each components of interest.
oxygenate is applied and the concentration of each oxygenate 7.1.2 Sample Introduction System—Any system capable of
calculated. introducing a representative 0.1 to 1.0-µL liquid sample into
the split inlet device of the gas chromatograph. Microlitre
NOTE 1—While 1,2-dimethoxyethane has been found to be an appro-
syringes, autosamplers, and liquid sampling valves have been
priate internal standard, other oxygenates may be used provided they are
used successfully. The split injector should be capable of
not present in the sample and do not interfere with any compound of
interest. accurate split control in the range from 10:1 to 500:1.
7.1.3 Carrier and Detector Gas Control—Constant flow
5. Significance and Use
control of carrier and detector gases is critical to optimum and
consistent analytical performance. Control is best provided by
5.1 In gasoline blending, the determination of organic
the use of pressure regulators and fixed flow restrictors. The
oxygenated compounds is important. Alcohols, ethers, and
gas flow rates are measured by any appropriate means. The
other oxygenates are added to gasoline to increase the octane
supply pressure of the gas delivered to the gas chromatograph
number and to reduce tailpipe emissions of carbon monoxide.
must be at least 70 kPa (10 psig) greater than the regulated gas
They must be added in the proper concentration and ratios to
at the instrument to compensate for the system back pressure.
meet regulatory limitations and to avoid phase separation and
In general, a supply pressure of 550 kPa (80 psig) will be
problems with engine performance or efficiency.
satisfactory.
5.2 This test method provides sufficient oxygen-to-hydro-
7.2 OFID Detector System, consisting of a cracking reactor,
carbon selectivity and sensitivity to allow determination of
methanizer, and FID.Aschematic of a typical OFID system is
oxygenates in gasoline samples without interference from the
shown in Fig. 1.
bulk hydrocarbon matrix.
7.2.1 The detector must meet or exceed the typical specifi-
cationsgiveninTable 1ofPracticeE594whileoperatinginthe
6. Theory of OFID Operation
normal FID mode as specified by the manufacturer.
6.1 The detection system selective for organic oxygen
7.2.2 In the OFID mode, the detector shall meet or exceed
consists of a cracking reactor, hydrogenating reactor (metha-
the following specifications: (a) equal to or greater than 10
nizer), and a flame ionization detector (FID). The cracking
linearity, (b) less than 100-ppm mass oxygen (1-ng O/s)
reactor, connected immediately after the gas chromatographic
sensitivity, (c) greater than 10 selectivity for oxygen com-
capillary column, consists of a Pt/Rh capillary tube. Carbon
pounds over hydrocarbons, (d) no interference from coeluting
monoxide (CO) is formed from compounds containing oxygen
compounds when 0.1 to 1.0-µLsample is injected, (e) equimo-
according to the following reaction:
lar response for oxygen.
C H O → zCO1~y/2!H 1~x 2 z!C (1)
x y z 2
7.3 Column—A 60-m by 0.25-mm inside diameter fused
silica open tubular column containing a 1.0-µm film thickness
6.2 An excess layer of carbon is created in the Pt/Rh tube of
of bonded methyl silicone liquid phase is used. Equivalent
the cracking reactor from the introduction of hydrocarbons
columns which provide separation of all oxygenates of interest
from the sample or, if so designed, from a hydrocarbon (for
may be used.
example,pentaneorhexane)dopingsystem,orboth.Thislayer
7.4 Integrator—Use of an electronic integrating device or
of carbon facilitates the cracking reaction and suppresses
computer is required. The device and software should have the
hydrocarbon response.
following capabilities:
6.3 The carbon monoxide formed in the cracking reactor is
7.4.1 Graphic presentation of the chromatogram,
convertedtomethaneinthehydrogenatingreactoraccordingto
7.4.2 Digital display of chromatographic peak areas,
the following reaction:
7.4.3 Identification of peaks by retention time,
CO 1 3H → CH 1 H O (2)
2 4 2
7.4.4 Calculation and use of response factors, and
The CH is subsequently detected with an FID.
7.4.5 Internal standard calculation and data presentation.
6.4 The methanizer consists either of a short porous layer
8. Reagents and Materials
opentubular(PLOT)glasscapillarytubeinternallycoatedwith
aluminum oxide with adsorbed nickel catalyst or stainless steel 8.1 Purity of Reagents—Reagents grade chemicals shall be
tubing containing a nickel-based catalyst. It is installed within used in all tests. Unless otherwise indicated, it is intended that
D5599–00 (2005)
FIG. 1 Schematic of an OFID
all reagents shall conform to the specifications of the Commit- 8.5.4 Additional purification of the carrier, air, and hydro-
tee onAnalytical Reagents of theAmerican Chemical Society, gen is recommended. Use molecular sieves, Drierite, charcoal,
where such specifications are available. Other grades may be or other suitable agents to remove water, oxygen, and hydro-
used, provided it is first ascertained that the reagent is of carbons from the gases.
sufficiently high purity to permit its use without lessening the 8.6 Sample Container—Glass vials with crimp-on or screw-
accuracy of the determination. down sealing caps with self-sealing polytetrafluoroethylene
8.2 Calibrant Materials—The following compounds may (PTFE)-faced rubber membranes are used to prepare calibra-
be used for calibrating the detector: methanol, ethanol, tion standards and samples for analysis.
n-propanol, iso-propanol, n-butanol, tert-butanol, sec-butanol,
9. Preparation of Apparatus
iso-butanol, tert-pentanol, methyl tert-butylether (MTBE),
9.1 Chromatograph and OFID—Place instrument and de-
tert-amylmethylether (TAME), ethyl tert-butylether (ETBE),
tector into operation in accordance with the manufacturer’s
di-iso-propylether (DIPE). (Warning—These materials are
instructions. Install the capillary column according to Practice
very flammable and may be harmful or fatal when ingested,
E1510. Adjust the operating conditions to provide for separa-
inhaled, or allowed to be absorbed through the skin.)
tion of all oxygenates of interest. Typical conditions used with
8.3 Internal Standard—Use one of the compounds listed in
the column specified in 7.3 are listed in Table 1.
8.2thatisnotpresentinthesample.Ifallofthematerialsin8.2
9.2 System Performance—At the beginning of each day of
are likely to be present in the test sample, use another organic
operation, inject an oxygenate-free gasoline sample into the
oxygenate of high-grade purity that is separated from all other
chromatograph to ensure minimum hydrocarbon response. If
oxygenates present (for example, 1,2-dimethoxyethane).
hydrocarbon response is detected, the OFID is not operating
8.4 Dopant—If the OFID is so designed, reagent-grade
effectively and must be optimized according to the manufac-
pentane is used as a hydrocarbon dopant for the cracking
turer’s instructions before the sample can be analyzed.
reactor. (Warning—Pentane is extremely flammable and
harmful when inhaled.)
TABLE 1 Typical Operating Conditions
8.5 Instrument Gases—The gases supplied to the gas chro-
Temperatures, °C
matograph and detector are:
Injector 250
8.5.1 Air, zero grade. (Warning—Compressed air is a gas
Column 50°C (hold 10 min), ramp 8°/min to 250°C
under high pressure and supports combustion.)
Detector Methanizer 350–450
8.5.2 Hydrogen, pure grade, 99.9 mol % minimum purity.
Reactor 850–1300
(Warning—Hydrogen is an extremely flammable gas under
Flows, mL/min
high pressure.)
Column carrier gas 1
8.5.3 Helium or nitrogen as column carrier gas, 99.995 mol
Detector gases Air: 300
H :30
% minimum purity, or a blend of 95 % helium/5 % hydrogen,
Auxiliary (for dopant, if available) H:0.6
depending on the instrument’s manufacturer. (Warning—
A
Sample Size 0.1–1.0 µL
Helium and nitrogen are compressed gases under high pres-
Split Ratio 100–1
sure.)
A
Sample size and split ratio must be adjusted so that the oxygenates in the
range from 0.1 to 20.0 mass % are eluted from the column and measured linearly
atthedetector.Eachlaboratorymustestablishandmonitortheconditionsthatare
Reagent Chemicals, American Chemical Society Specifications, American
needed to maintain linearity with their individual instruments. Nonlinearity is most
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
commonly observed when using an OFID with samples containing high levels of
listed by the American Chemical Society, see Analar Standards for Laboratory
individual oxygenates and can be compensated for by either decreasing the
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
sample size, increasing the split ratio, or diluting the sample with an oxygenate-
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
free gasoline. A sample size of 0.5 µL and a split ratio of 100:1 has been used
MD. successfully in most cases.
D5599–00 (2005)
10. Calibration and Standardization
10.1 Retention Time Identification— Determine the reten-
tion time of each oxygenate component by injecting small
amounts either separatel
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