ASTM D7716-11a(2020)

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.
Designation: D7716 − 11a (Reapproved 2020)
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 3. Terminology
1.1 This test method provides for the quantitative determi- 3.1 Definitions—This test method makes reference to many
nation of residual methanol in glycerin by gas chromatography. common gas chromatographic procedures, terms, and relation-
The range of detection for residual methanol is 0.02 to 0.60 ships. Detailed definitions can be found in Practices E355 and
mass %. E594.
1.2 The values stated in SI units are to be regarded as
4. Summary of Test Method
standard. No other units of measurement are included in this
4.1 The sample is analyzed by headspace gas chromatogra-
standard.
phy. Calibration is achieved by the use of external standards of
1.3 This standard does not purport to address all of the
methanol in water.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Significance and Use
priate safety, health, and environmental practices and deter-
5.1 Methanol content reflects the quality of glycerin for use
mine the applicability of regulatory limitations prior to use.
as an engine coolant. The current specification for the maxi-
1.4 This international standard was developed in accor-
mum methanol content is 0.1 % weight to weight (w/w).
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
6. Apparatus
Development of International Standards, Guides and Recom-
6.1 Chromatographic System—See Practice E355 for spe-
mendations issued by the World Trade Organization Technical
cific designations and definitions. The gas chromatograph (GC)
Barriers to Trade (TBT) Committee.
system shall be capable of operating at the conditions given in
Table 1.
2. Referenced Documents
6.2 Autosampler system, Gerstel multipurpose sampler
2.1 ASTM Standards:
MPS-2 or equivalent. This method can also be run manually.
D1193 Specification for Reagent Water
D7640 Specification for Engine Coolant Grade Glycerin
6.3 Column, open tubular column with polyethylene glycol
E177 Practice for Use of the Terms Precision and Bias in
(PEG) bonded and cross-linked phase internal coating. The
ASTM Test Methods
column should have an upper temperature limit of 260 °C. A
E355 Practice for Gas Chromatography Terms and Relation-
column 30 m in length, with an internal diameter of 0.32 mm,
ships
and a 1.0 μm film thickness has been found satisfactory. Any
E594 Practice for Testing Flame Ionization Detectors Used
column with equivalent or better chromatographic efficiency
in Gas or Supercritical Fluid Chromatography
and selectivity can be used.
E691 Practice for Conducting an Interlaboratory Study to
6.4 Electronic Data Acquisition System—A computer ca-
Determine the Precision of a Test Method
pable of providing real-time graphic and digital presentation of
the chromatographic data is recommended for use. Peak areas
and retention times shall be measured by computer or elec-
This test method is under the jurisdiction of ASTM Committee D15 on Engine
tronic integration (integrator).
Coolants and Related Fluids and is the direct responsibility of Subcommittee
D15.04 on Chemical Properties.
Current edition approved Jan. 1, 2020. Published January 2020. Originally
approved in 2011. Last previous edition approved in 2011 as D7716–11a. DOI: The sole source of supply of the apparatus known to the committee at this time
10.1520/D7716–11AR20. 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
Standards volume information, refer to the standard’s Document Summary page on careful consideration at a meeting of the responsible technical committee, which
the ASTM website. you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7716 − 11a (2020)
TABLE 1 Operating Conditions
9. Calibration and Standardization
Injector: Hot split/splitless, 240 °C, 10:1 split ratio
9.1 Preparation of Calibration Stock Standard—Prepare a
Sample Size: 1.0 mL
stock methanol standard by weighing approximately 1.5 g of
Column Temperature Program: Initial temperature: 50 °C hold 8 min,
ramp at 20 °C ⁄min to 200 °C, hold for 0 min
methanol into a clean 100 mL volumetric flask. Record weight
Detector: Flame ionization at 250 °C
to the nearest 0.1 mg. Dilute with Specification D1193 Type II
Carrier gas: helium or hydrogen, 1.5 mL/min
water to the 100 mL mark and mix well. This test method
Vial incubation time: 20 min
Vial incubation temperature: 80 °C
contains approximately 15 000 ppm of methanol.
Agitator speed: 600 rpm
Injection speed: 200 μL/s 9.2 Standard Solutions—Prepare six calibration standards
Pull-up delay: 5 s
by first pipeting 2.0 mL of the stock standard into a 100 mL
volumetric flask, dilute with Specification D1193 Type II water
to the mark and mix well. This standard contains approxi-
7. Reagents and Materials
mately 300 ppm of methanol. Pipette 5 mL of this standard into
7.1 Purity of Reagents—Reagent-grade chemicals shall be a 10 mL volumetric flask, dilute with Specification D1193 Type
used in all tests. Unless otherwise indicated, it is intended that II water to the mark and mix well. This standard contains
all reagents conform to the specifications of the Committee on approximately 150 ppm of methanol. Pipette 5 mL of this
Analytical Reagents of the American Chemical Society where standard into a 10 mL volumetric flask, dilute with Specifica-
such specifications are available. Other grades may be used tion D1193 Type II water to the mark and mix well. This
provided it is first ascertained that the reagent is of sufficient standard contains approximately 75 ppm of methanol. Make
purity to permit its use without lessening the accuracy of the three more dilutions in the same manner to give solutions with
determination. methanol concentrations of approximately 37.5, 18.8, and 9.4
ppm. There will be six calibration standards with approximate
7.2 Purity of Water—Unless otherwise indicated, references
concentrations of 9.4, 18.8, 37.5, 75, 150, and 300 ppm of
to water shall be understood to mean reagent water as defined
methanol.
by Type II of Specification D1193.
9.3 Chromatographic Analysis—Pipette 1.0 mL of each of
7.3 Methanol, reagent grade.
the prepared standards into each of six 20 mL headspace vials.
7.4 Glycerin, meeting Specification D7640.
Pipette 5.0 mL of Specification D1193 Type II water into each
7.5 Carrier gas, hydrogen or helium of high purity. Addi- of the vials and cap tightly with a PTFE-lined septa. Also
tional purification is recommended by the use of molecular prepare two air blank vials that should be run for the first vial
sieves or other suitable agents to remove water, oxygen, and to check the system background and also after the highest
hydrocarbons. Available pressure shall be sufficient to ensure a calibration standard to check for carryover.
constant carrier gas flow rate.
9.4 Analyze the calibration standards under the same oper-
7.6 Microlitre syringe on auto sampler, 2500 μL capacity. ating conditions as the sample solutions. If using a manual
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 syringe needle into the vial through
the septa. Withdraw the headspace gas up past the 1 mL mark
7.10 Volumetric flasks, various capacities.
and inject back into the vial. Repeat this two more times.
7.11 Forced-air oven, 80 6 1 °C (needed for manual
Withdraw headspace gas again up past the 1 mL mark and
injectio
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