ASTM D7716-11

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D7716–11
Standard Test Method for
Determination of Residual Methanol in Glycerin by Gas
Chromatography
This standard is issued under the fixed designation D7716; 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 5. Significance and Use
1.1 This test method provides for the quantitative determi- 5.1 Methanol content reflects the quality of glycerin for use
nationofresidualmethanolinglycerinbygaschromatography. as an engine coolant. The current specification for the maxi-
The range of detection for residual methanol is 0.02 to 0.60 mum methanol content is 0.1 % weight to weight (w/w).
mass %.
6. Apparatus
1.2 The values stated in SI units are to be regarded as
6.1 Chromatographic System—See Practice E355 for spe-
standard. No other units of measurement are included in this
standard. cificdesignationsanddefinitions.Thegaschromatograph(GC)
system shall be capable of operating at the conditions given in
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the Table 1.
6.2 Autosampler system, Gerstel multipurpose sampler
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- MPS-2 or equivalent. This method can also be run manually.
6.3 Column, open tubular column with polyethylene glycol
bility of regulatory limitations prior to use.
(PEG) bonded and cross-linked phase internal coating. The
2. Referenced Documents
column should have an upper temperature limit of 260°C. A
2.1 ASTM Standards: column 30 m in length, with an internal diameter of 0.32 mm,
D1193 Specification for Reagent Water and a 1.0-µm film thickness has been found satisfactory. Any
D7640 Specification for Engine Coolant Grade Glycerin column with equivalent or better chromatographic efficiency
E355 Practice for Gas Chromatography Terms and Rela- and selectivity can be used.
tionships 6.4 Electronic Data Acquisition System—A computer ca-
E594 Practice for Testing Flame Ionization Detectors Used pable of providing real-time graphic and digital presentation of
in Gas or Supercritical Fluid Chromatography the chromatographic data is recommended for use. Peak areas
and retention times shall be measured by computer or elec-
3. Terminology
tronic integration (integrator).
3.1 Definitions—This test method makes reference to many
7. Reagents and Materials
common gas chromatographic procedures, terms, and relation-
ships. Detailed definitions can be found in Practices E355 and 7.1 Purity of Reagents—Reagent-grade chemicals shall be
E594. used in all tests. Unless otherwise indicated, it is intended that
all reagents conform to the specifications of the Committee on
4. Summary of Test Method
Analytical Reagents of the American Chemical Society where
4.1 The sample is analyzed by headspace gas chromatogra-
phy. Calibration is achieved by the use of external standards of
methanol in water.
This test method is under the jurisdiction ofASTM Committee D15 on Engine
Coolants and is the direct responsibility of Subcommittee D15.93 on Research and
Long Range Planning.
Current edition approved June 1, 2011. Published August 2011. DOI: 10.1520/ The sole source of supply of the apparatus known to the committee at this time
D7716-11. is GERSTEL GmbH & Co.KG, Eberhard- Gerstel-Platz 1, 45473 Mülheim an der
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Ruhr, Germany. If you are aware of alternative suppliers, please provide this
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM information to ASTM International Headquarters. Your comments will receive
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D7716–11
TABLE 1 Operating Conditions
9.2 Standard Solutions—Prepare six calibration standards
Injector: Hot split/splitless, 240°C, 10:1 split ratio by first pipeting 2.0 mL of the stock standard into a 100-mL
Sample Size: 1.0 mL
volumetric flask, dilute with Specification D1193Type II water
Column Temperature Program: Initial temperature: 50°C hold 8 min,
to the mark and mix well. This standard contains approxi-
ramp at 20°C/min to 200°C, hold for 0 min
Detector: Flame ionization at 250°C
mately300ppmofmethanol.Pipette5mLofthisstandardinto
Carrier gas: helium or hydrogen, 1.5 mL/min
a 10-mL volumetric flask, dilute with Specification D1193
Vial incubation time: 20 min
Type II water to the mark and mix well. This standard contains
Vial incubation temperature: 80°C
Agitator speed: 600 rpm
approximately 150 ppm of methanol. Pipette 5 mL of this
Injection speed: 200 µL/s
standard into a 10-mL volumetric flask, dilute with Specifica-
Pull-up delay: 5 s
tion D1193 Type II water to the mark and mix well. This
standard contains approximately 75 ppm of methanol. Make
three more dilutions in the same manner to give solutions with
such specifications are available. Other grades may be used
methanol concentrations of approximately 37.5, 18.8, and 9.4
provided it is first ascertained that the reagent is of sufficient
ppm. There will be six calibration standards with approximate
purity to permit its use without lessening the accuracy of the
concentrations of 9.4, 18.8, 37.5, 75, 150, and 300 ppm of
determination.
methanol.
7.2 Purity of Water—Unless otherwise indicated, references
9.3 Chromatographic Analysis—Pipette 1.0 mL of each of
to water shall be understood to mean reagent water as defined
the prepared standards into each of six 20-mLheadspace vials.
by Type II of Specification D1193.
Pipette 5.0 mL of Specification D1193 Type II water into each
7.3 Methanol, reagent grade.
of the vials and cap tightly with a PTFE-lined septa. Also
7.4 Glycerin, meeting Specification D7640.
prepare two air blank vials that should be run for the first vial
7.5 Carrier gas, hydrogen or helium of high purity. Addi-
to check the system background and also after the highest
tional purification is recommended by the use of molecular
calibration standard to check for carryover.
sieves or other suitable agents to remove water, oxygen, and
hydrocarbons.Available pressure shall be sufficient to ensure a 9.4 Analyze the calibration standards under the same oper-
ating conditions as the sample solutions. If using a manual
constant carrier gas flow rate.
7.6 Microlitre syringe on auto sampler, 2500-µL capacity. injection technique, place the first calibration standard vial into
7.7 Microlitre syringe, gastight, 1000-µL capacity (needed an 80°C forced-air oven and allow to incubate for 20 min.Also
for manual injections). place the 1-mL syringe into the oven to become equilibrated
7.8 Screw-cap vials, with polytetrafluoroethylene (PTFE)- with the standard vial. When the time has elapsed, remove the
faced septa, 20-mL capacity.
syringe using heat-resistant gloves. Remove the calibration
7.9 Volumetric pipets, various capacities.
standard vial and insert the sy
...