ASTM D7059-21

Standard Test Method for Determination of Methanol in Crude Oils by Multidimensional Gas Chromatography

SIGNIFICANCE AND USE
5.1 Methanol is used in production of crude oil to prevent formation of gas hydrates. The presence of residual methanol in crude oils can lead to costly problems in refinery operations.
SCOPE
1.1 This test method covers the determination of methanol in crude oils by direct injection multidimensional gas chromatography in the concentration range of 15 ppm (m/m) to 900 ppm (m/m). The pooled limit of quantification (PLOQ) is 15 ppm (m/m).  
1.2 This test method is applicable only to crude oils containing less than or equal to 0.1 % (v/v) water.  
1.3 This test method has not been tested with crude oil samples that are solid or waxy, or both, at ambient temperatures.  
1.4 The values stated in SI units are to be regarded as standard. Alternate units, in common usage, are also provided to increase clarity and aid the users of this test method.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

General Information

• Status: Published
• Publication Date: 30-Nov-2021
• ICS: 75.040 - Crude petroleum
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0L - Gas Chromatography Methods

Relations

• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM E594-96(2019) - Standard Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
• Effective Date: 01-Sep-2019
• Refers: ASTM D4006-16 - Standard Test Method for Water in Crude Oil by Distillation
• Effective Date: 01-Jun-2016
• Refers: ASTM D4307-99(2015) - Standard Practice for Preparation of Liquid Blends for Use as Analytical Standards
• Effective Date: 01-Oct-2015
• Refers: ASTM D4928-12 - Standard Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration
• Effective Date: 01-Dec-2012
• Refers: ASTM D4006-11(2012) - Standard Test Method for Water in Crude Oil by Distillation
• Effective Date: 01-Nov-2012
• Refers: ASTM E594-96(2011) - Standard Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
• Effective Date: 01-Nov-2011
• Refers: ASTM D4928-11 - Standard Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration
• Effective Date: 01-Jun-2011
• Refers: ASTM D4057-06(2011) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• Effective Date: 01-Jun-2011
• Refers: ASTM D4006-11 - Standard Test Method for Water in Crude Oil by Distillation
• Effective Date: 01-Jun-2011
• Refers: ASTM D6596-00(2011) - Standard Practice for Ampulization and Storage of Gasoline and Related Hydrocarbon Materials
• Effective Date: 01-May-2011
• Refers: ASTM D4928-00(2010) - Standard Test Methods for Water in Crude Oils by Coulometric Karl Fischer Titration
• Effective Date: 01-Jun-2010
• Refers: ASTM D4307-99(2010) - Standard Practice for Preparation of Liquid Blends for Use as Analytical Standards
• Effective Date: 01-May-2010
• Refers: ASTM D4006-07 - Standard Test Method for Water in Crude Oil by Distillation
• Effective Date: 01-Aug-2007

Overview

ASTM D7059-21 is a standardized test method developed by ASTM International for the Determination of Methanol in Crude Oils by Multidimensional Gas Chromatography. This method is vital for the petroleum industry, as methanol is frequently used during crude oil production to inhibit gas hydrate formation. Detecting and quantifying residual methanol in crude oil is essential because its presence can cause significant operational and economic challenges during refining.

The method utilizes direct injection multidimensional gas chromatography, providing reliable measurement of methanol concentrations in crude oil samples containing less than or equal to 0.1% (v/v) water. The applicable concentration range for methanol detection is 15 ppm (m/m) to 900 ppm (m/m), supporting both quality assurance and regulatory compliance in oil production and refining.

Key Topics

• Scope of Application

  • Applicable for crude oil samples with ≤0.1% (v/v) water content
  • Methanol quantification range: 15 ppm to 900 ppm (m/m)
  • Not validated for solid or waxy crude samples at ambient temperature

• Significance and Use

  • Identifies residual methanol from production processes
  • Supports operational decision-making by preventing potential refinery upsets and corrosion
  • Enhances safety, product quality, and cost-efficiency in oil processing

• Testing Method

  • Employs direct injection multidimensional gas chromatography (GC)
  • Uses dual columns (pre-column and oxygenates-selective column) and an internal standard for reliable quantitation
  • Relies on flame ionization detectors for precise measurement of methanol and 1-propanol (internal standard)
  • Requires representative sampling and proper sample preparation per referenced ASTM practices

• Analytical Precision

  • Offers a pooled limit of quantification at 15 ppm (m/m)
  • Includes calibration procedures and quality control with standardized methanol-in-crude oil solutions

• Safety and Quality

  • Emphasizes establishment of appropriate safety, health, and environmental practices
  • Requires periodic calibration and use of quality control standards to ensure data integrity

Applications

• Oil Production and Refining

  • Ensures accurate detection and quantification of methanol, enabling operational adjustments to avoid costly refinery issues
  • Helps in complying with quality control requirements and environmental regulations

• Laboratory Testing

  • Provides a standardized approach for crude oil testing laboratories to quantify methanol content with reproducibility and traceability

• Pipeline and Storage Quality Monitoring

  • Facilitates regular inspection of crude oil during transportation and storage to prevent methanol contamination from impacting downstream processing

• Regulatory Compliance

  • Supports oil producers and refiners in meeting national and international mandates concerning fuel and crude oil specifications

Related Standards

The following ASTM standards are referenced or useful in conjunction with ASTM D7059-21 for comprehensive crude oil analysis and gas chromatography procedures:

• ASTM D4006: Standard Test Method for Water in Crude Oil by Distillation
• ASTM D4057: Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4175: Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• ASTM D4307: Practice for Preparation of Liquid Blends for Use as Analytical Standards
• ASTM D4928: Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration
• ASTM D6596: Practice for Ampulization and Storage of Gasoline and Related Hydrocarbon Materials
• ASTM E355: Practice for Gas Chromatography Terms and Relationships
• ASTM E594: Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography

By adhering to ASTM D7059-21 and related standards, oil and gas industry professionals can confidently assess methanol content in crude oil, optimize refining processes, and safeguard product quality.

Standards Content (Sample)

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:D7059 −21
Standard Test Method for
Determination of Methanol in Crude Oils by
Multidimensional Gas Chromatography
This standard is issued under the fixed designation D7059; 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* D4175 Terminology Relating to Petroleum Products, Liquid
Fuels, and Lubricants
1.1 This test method covers the determination of methanol
D4307 Practice for Preparation of Liquid Blends for Use as
in crude oils by direct injection multidimensional gas chroma-
Analytical Standards
tography in the concentration range of 15 ppm (m/m) to
D4928 Test Method for Water in Crude Oils by Coulometric
900 ppm (m/m). The pooled limit of quantification (PLOQ) is
Karl Fischer Titration
15 ppm (m/m).
D6596 Practice for Ampulization and Storage of Gasoline
1.2 This test method is applicable only to crude oils con-
and Related Hydrocarbon Materials
taining less than or equal to 0.1 % (v/v) water.
E355 Practice for Gas ChromatographyTerms and Relation-
ships
1.3 This test method has not been tested with crude oil
samples that are solid or waxy, or both, at ambient tempera- E594 Practice for Testing Flame Ionization Detectors Used
in Gas or Supercritical Fluid Chromatography
tures.
1.4 The values stated in SI units are to be regarded as
3. Terminology
standard. Alternate units, in common usage, are also provided
3.1 Definitions:
to increase clarity and aid the users of this test method.
3.1.1 This test method makes reference to common gas
1.5 This standard does not purport to address all of the
chromatographicprocedures,terms,andrelationships.Detailed
safety concerns, if any, associated with its use. It is the
definitions of these can be found in Practices E355 and E594,
responsibility of the user of this standard to establish appro-
and Terminology D4175. Additional definitions and informa-
priate safety, health, and environmental practices and deter-
tion pertinent to this test method are listed below.
mine the applicability of regulatory limitations prior to use.
3.1.2 analytical column, n—porous layer open tubular
1.6 This international standard was developed in accor-
(PLOT) column with a stationary phase selective for oxygen-
dance with internationally recognized principles on standard-
ates; it is used to resolve methanol from 1-propanol to provide
ization established in the Decision on Principles for the
accurate quantitative results.
Development of International Standards, Guides and Recom-
3.1.3 cool-on-column injector, n—an injection port that
mendations issued by the World Trade Organization Technical
allowscontrolledinjectionofthesampleatatemperatureclose
Barriers to Trade (TBT) Committee.
to or lower than the boiling point of the solvent into the gas
chromatographic column or a liner within the injection port
2. Referenced Documents
connected to the column.
2.1 ASTM Standards:
3.1.3.1 Discussion—After the injection, the injection port is
D4006 Test Method for Water in Crude Oil by Distillation
heated at a fixed rate to a temperature sufficiently high enough
D4057 Practice for Manual Sampling of Petroleum and
to allow the transfer of sample components of interest from the
Petroleum Products
injection port to the part of the column located in the gas
chromatograph (GC) oven.
3.1.4 electronic pressure control, n—electronic pneumatic
This test method is under the jurisdiction of ASTM Committee D02 on
control of carrier gas flows; it can be flow or pressure
Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of
Subcommittee D02.04.0L on Gas Chromatography Methods. programmed to speed up elution of components.
Current edition approved Dec. 1, 2021. Published December 2021. Originally
3.1.5 low-volume connector, n—a special union for connect-
approved in 2004. Last previous edition approved in 2017 as D7059 – 09 (2017).
ing two lengths of tubing 1.6 mm inside diameter and smaller;
DOI: 10.1520/D7059-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
sometimes referred to as a zero dead-volume union.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3.1.6 pre-column, n—a polydimethylsiloxane WCOT col-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. umn used to isolate the methanol and 1-propanol and several
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7059−21
TABLE 1 Operating Conditions for Configuration A
Injector On-column. Temperature program: 50 °C (0.1 min) 30 °C ⁄min to 300 °C until end of oven program; 1.0 microlitre injected with autosampler
Oven 40 °C at 2 °C ⁄min to 70 °C (0 min); 4 °C ⁄min to 190 °C; 30 °C ⁄min to 250 °C (13.0 min)
temperature
program
Detectors Two flame ionization detectors (FID) at 325 °C. Hydrogen at 30 mL/min; air at 300 mL/min; helium make-up gas at 30 mL/min
Columns 60m×0.53mmID5.0 µm filmpolydimethylsiloxane (pre-column)
10m×0.53mmID10µmfilm CP-Lowox
The two columns are coupled through a four-port Valco valve as shown in Fig. 1
When analyses are not being performed, the GC oven temperature should be kept at 250 °C, and the pre-column carrier head pressure kept at 60
psi. This procedure conditions the CP-Lowox column, which may trap carrier gas contaminants at the normal 40 °C starting temperature, and also
elutes residual heavy material from the pre-column.
Carrier Pre-column: 10 psi (20 min) 99 psi/min to 60 psi (until end of oven temperature program)
gas
CP-Lowox column flow: constant flow of 10 mL/min
Valve 260 °C
temperature
Valve 1. Valve on at 2.80 min and off at 4.00 min to transfer the methanol from the polydimethylsiloxane column to the CP-Lowox column
timing
2. Valve on at 6.80 min and off at 8.00 min to transfer the internal standard, 1-propanol
light hydrocarbons from the higher boiling portion of the crude analytical PLOT column for oxygenates. While the methanol
oil sample for transfer to the analytical column for further and 1-propanol are eluting from the analytical PLOT column
separation and quantification. for oxygenates, auxiliary carrier gas is used to elute higher
boiling crude oil hydrocarbons from the pre-column, either in
3.1.7 programmable temperature vaporizer (PTV), n—a
theforwardorbackflushmode,toyieldastablebaselineforthe
temperature programmable injector similar to a cool-on-
next analysis.
column injector except that the sample is injected cool into a
glass liner or insert instead of the WCOT (3.1.6) column and
5. Significance and Use
then the temperature is programmed in a manner similar to the
5.1 Methanol is used in production of crude oil to prevent
on-column injector.
formation of gas hydrates. The presence of residual methanol
3.1.7.1 Discussion—The liner may be replaced, as
in crude oils can lead to costly problems in refinery operations.
necessary, to remove non-volatile materials. This injector may
be operated in low split mode or direct (no splitting) mode.
6. Apparatus
3.1.8 split/splitless injector, n—a heated capillary inlet or
6.1 Chromatograph—A multidimensional two-WCOT col-
sample introduction system that allows controlled splitting of
umn gas chromatographic system, capable of adequately re-
the injected sample into two unequal portions, the smaller of
solving methanol and the 1-propanol internal standard and of
which goes to the capillary column, and the greater to a vent.
eliminating hydrocarbon and other interferences, is required
3.1.8.1 Discussion—When the vent is closed, the entire
for this analysis. Flow switching between the two specified
sample enters the capillary column and the inlet is operated as
WCOT columns may be accomplished by either using a valve
a splitless injector. When the vent is open, the inlet is operated
or pneumatic (pressure) switching to redirect flows. The
in the split mode and only a portion of the sample reaches the
unwanted higher boiling hydrocarbons may be removed from
capillary column. The ratio of the split between the capillary
the pre-column either by forward flush or backward flush. The
column and the vent is calculated as described in 3.1.8.1.
system requires that carrier gas flow controllers must be
3.1.8.1 split ratio, n—in capillary gas chromatography, the
capable of precise control for the typical pressures required.
ratio of the total flow of carrier gas to the sample inlet versus
Such flow controllers are available on gas chromatographs.
the flow of the carrier gas to the capillary column, expressed
The precision of this test method was obtained using several
by:
instrument configurations described in 6.1.1 – 6.1.5. Other
multidimensional configurations may be used, provided that
split ratio 5 ~S1C!/C (1)
they meet all of the requirements of this test method.
where:
6.1.1 Configuration A—Cool-on-column injection (no back-
S = flow rate at the splitter vent, and
flush of pre-column) with two separate selective heartcuts for
C = flow rate at the column outlet.
the methanol and 1-propanol internal standard. The chromato-
graphic instrument can be operated at the approximate condi-
4. Summary of Test Method
tionsgiveninTable1andFig.1.Figs.2-5givechromatograms
4.1 Aninternalstandard,1-propanol,isaddedtothesample, and a calibration curve.
which is then introduced into a gas chromatograph equipped 6.1.2 Configuration B—Heated split injection with a single
with two columns and a flow switching system between the heartcut of methanol, 1-propanol and several C minus hydro-
two columns. The sample first passes through the polydimeth- carbons transferred to the PLOT column for oxygenates using
ylsiloxaneWCOTcolumnthatperformsapre-separationofthe a six-port valve. The pre-column, located in a separate auxil-
methanol and 1-propanol and eliminates unwanted hydrocar- iary oven, is backflushed to a vent using the six-port valve.
bons. The methanol and 1-propanol are transferred to the Table 2 and Fig. 6 give details of the configuration.
D7059−21
FIG. 1Valve Diagram for Configuration A
NOTE 1—Two separate injections: TOP/ methanol/1-propanol internal standard solution and BOTTOM/crude oil only.
FIG. 2Relative Retention Windows on Polydimethylsiloxane Pre-column in Configuration A Using Monitor FID
6.1.3 Configuration C—Heated split injection with a single 6.2 Detector—At least one, main flame ionization detector
heartcut for the methanol, 1-propanol and C minus (FID) is required. In a two FID detector configuration, the
hydrocarbons, followed by backflush of the pre-column optional second detector is used to monitor the pre-column
through the injection port to remove the high boiling hydro-
elution and aids in setting heartcut or transfer times for the
carbons retained on the pre-column. The chromatographic
methanol and 1-propanol. The main detector’s response, pro-
instrumentcanbeoperatedattheapproximateconditionsgiven
portionaltotheconcentrationsofthemethanoland1-propanol,
in Table 3 and Fig. 7. The pre-column is located in a separate
isrecorded;thepeakareasaremeasured;andtheconcentration
auxiliary oven. Fig. 8 gives a chromatogram obtained with this
of methanol is calculated with reference to the 1-propanol
system.
internal standard and a calibration curve.
6.1.4 Configuration D—Direct PTV (no splitting) injection
6.3 Valve or Pneumatic (pressure) Switching, for systems
with a single heartcut for the methanol and the 1-propanol
using valve switching (for example, Configurations A, B in
internal standard and several low boiling hydrocarbons, fol-
6.1), a high temperature and low volume valve, located within
lowed by backflush of the pre-column through the injector to a
the gas chromatographic column oven or in a separate oven,
vent by pressure switching. Table 4 and Figs. 9 and 10 give
capableofperformingthefunctionsdescribedin6.1.Thevalve
flow configurations and operating conditions.
connections shall not contribute significantly to chromato-
6.1.5 Configuration E—Split injection using pressure
graphic deterioration. Refer to Fig. 2, Fig. 3, and Fig. 8 for
switching between the pre-column and the analytical column.
compound peak performance, manufacturer’s guidelines and
After transfer to the analytical column, pressure is reduced at
the inlet and the pre-column is backflushed to remove high examples given in 6.1 as a guide in assembling the GC system.
For example, Valco Model No. A 4C10WP, 1.6 mm ( ⁄16 in.)
boiling crude components. Table 5 and Fig. 11 give the flow
configurations and operating conditions. fittings was used in Configuration A (6.1). Other equivalent
D7059−21
FIG. 3Chromatogram of Methanol and 1-propanol Internal Standard with Configuration A
FIG. 4Chromatogram of 5 ppm Methanol with Configuration A
valves may be used. Alternatively, pneumatic or pressure Generally, splitless or direct injection types allow detection of
switching may be used instead of a valve (for example, lowerlevels(1ppmorless)ofmethanol.Thesplitlessordirect
Configurations C, D, and E in 6.1).
injection systems include: (A) a cool-on-column temperature
6.3.1 When using valve switching for heart-cutting, an
programmable vaporizer, and appropriate autosampler to allow
automatic valve-switching device must be used to ensure
such injections (Configuration A in 6.1); and (B) PTV (Con-
repeatable switching times. Such a device must be synchro-
figuration D in 6.1). Alternatively, heated, splitting type injec-
nized with injection and data collection times. For the pressure
torsmaybeusedwithlowsplitratios(ConfigurationsB,C,and
switching (Configurations C, D, and E) approach, automatic
Ein 6.1). The splitting type of injection generally is applicable
precise and stable pressure control must be used to yield stable
for concentrations greater than or equal to 2 ppm methanol.
retention times.
With splitting type injectors, the replaceable glass deactivated
6.4 Injection System—Several sample injection systems
liner (single-taper style with deactivated glass wool at the
have been used successfully with the configurations in 6.1.
D7059−21
FIG. 5Calibration Curve of 1 to 1000 ppm Methanol with Configuration A
TABLE 2 Operating Conditions for Configuration B
the column in 6.7, except if located in a separate auxiliary
Column 1 (pre-column) 10 m × 0.53 mm oven.Theconfigurationsin6.1giveexamplesofcolumnsused
polydimethylsiloxane (5 µm
successfully.
film)
Column 2 10 m × 0.53 mm CP-Lowox
6.7 Analytical Column, a PLOT column for oxygenates,
(10 µm film)
10 mlongby0.53 mmI.D.,withastationaryphasecoatedonto
Injector type Capillary Split
Injector split ratio 5:1
a fused silica capillary or equivalent. At a minimum, the
Injection size 2 µL (with autosampler)
column shall have sufficient retention for methanol that it
Injector temperature 350 °C
elutes after n-tridecane (retention index >1300) at 150 °C, and
Pre-column oven 300 °C
Detector temperature 300 °C
have sufficient efficiency and capacity to resolve methanol
Oven temperature 125 °C (2 min) 20 °C ⁄min to
from 1-propanol to provide accurate quantitative results. En-
300 °C (4.25 min)
sure that acetone does not interfere with the methanol analysis
Carrier gas Helium
Carrier gas flow rate 10 mL/min
by analyzing a 1000 ppm mixture of acetone in crude oil
containingthe1-propanolinternalstandardafterthesystemhas
been optimized.
bottom to retain unvaporized components) was used success-
fully (for example, as in Configuration C in 6.1).
7. Reagents and Materials
6.4.1 Automatic microlitre syringe injectors must be used
7.1 Carrier Gas—Helium and ultrapure nitrogen have been
for introducing representative samples into the GC inlet.
used successfully. The minimum purity of the carrier gas used
Cool-on-column automated injectors may need special syringe
must be 99.95 mole %. Oxygen scrubbers are recommended to
needles, and so forth. Follow the manufacturer’s instructions.
safeguard the WCOT columns.
6.5 Data Presentation or Calculation:
7.2 Methanol, >99.9 % pure (Warning—Flammable; vapor
6.5.1 Recorder—A data system is used for recording and
harmful).
evaluating the chromatograms.
6.5.2 Integrator or Computer—A computer or electronic
7.3 1-Propanol, >99.9 % pure, and containing <500 ppm
integrator is used to obtain peak areas.
methanol (Warning—Flammable; vapor harmful).
6.6 Pre-column WCOT, containinga5µmfilm thickness of
7.4 Toluene,>99.9 %pure,andcontaining<0.5ppmmetha-
cross-linkedpolymethyldisiloxane,orequivalent,tomeetallof
nol (Warning—Flammable; vapor harmful).
the requirements in this test method. This column performs a
pre-separation of the methanol and 1-propanol internal stan- 7.5 Quality Control Standards, containing known concen-
dard from hydrocarbons in the same boiling point range. The trations of methanol in crude oils (Warning—Flammable;
column shall perform at the same temperature as required for vapor harmful).
D7059−21
FIG. 6Valve Diagram for Configuration B
TABLE 3 Configuration C (Pressure Switching and Backflush of Pre-column) Approximate Operating Conditions
(Pre-column in Isothermal Second Oven)
Injector Split/splitless. 4:1 split ratio; 325 °C; 1.0 microlitre injected with autosampler
Oven temperature program (contains CP-Lowox WCOT column) 125 °C (3 min.) 20 °C ⁄min. to 300 °C (10 min)
Prefac oven (contains pre-column) temp 300 °C
Detectors Single flame ionization detector (FID) at 350 °C. Hydrogen at 35 mL/min; air at
350 mL/min; make-up gas at 20 mL/min
Columns 10m×0.53mmID5.0 µm filmpolydimethylsiloxane (pre-column)
10m×0.53mmID10µmfilm CP-Lowox
The two columns are coupled through a pressure switching coupling as shown in
Fig. 6
Carrier gas Helium at a linear velocity of 120 cm/s
Pre-column backflush timing 15 s to 20 s
8. Sampling mixed or composite sampling is recommended when sampling
from a large source of the crude oil. Follow the recommenda-
8.1 Ensure that the sample is representative of the crude oil
tions of Practice D4057, or its equivalent, when obtaining
from which it is taken. The use of multiple samples which are
D7059−21
FIG. 7Schematic of Configuration C (Table 3)
samples from bulk storage or pipelines.The use of epoxy-lined 8.1.1 Methanol content by this test method must be deter-
cans is recommended for storage or shipping, or both, of the mined on a sample containing less than or equal to 0.1 % (v⁄v)
sample. water. All of the crude oil samples used in the cooperative
D7059−21
FIG. 8Chromatogram Obtained with Configuration C
TABLE 4 Configuration D (Pressure Switching and Backflush of Pre-column) Approximate Operating Conditions
(Pre-column and Polar WCOT in Same Oven)
Gas chromatography (GC):
Pre-column/analytical WCOT’s CP SIL 5CB 10m×0.53mmIDdf=5.0µmand CP-Lowox 10 m ×
0.53 mm ID
Injector type PTV direct injection (packed columns equipped with adapter for
installing 0.53 mm ID wide bore WCOT)
Injector split ratio Direct injection: no split
Injection size 1.0 µL
Injector temperature 250 °C isothermal
Oven temperature 100 °C (2.5 min); 40 °C ⁄min to 290 °C (25.0 min)
Carrier gas Nitrogen
Carrier gas flow rates Flow at the detector in forward flush 15 mL/min. Flow at the detector
in backflush 8 mL/min
study to develop the precision of this test method contained to erroneous results. Heating samples to attain homogeneity
less than or equal to 0.1 % (v/v) water. Determine the water may result in the loss of methanol during sample transfers.
NOTE 2—Waxy and solid samples were not evaluated by this test
content using Test Method D4928, Test Method D4006,or
method. For such samples, it may be necessary to heat the sample to a
equivalent.
temperature of 20 °C above the expected pour point in the original
NOTE 1—The methanol content in crude oils is the combined methanol container. The sample is shaken vigorously to mix the sample. To avoid
losses of the methanol, an aliquot for analysis may be transferred under
content in the crude oil and, if present, in the associated water. It is known
that some crude oils are associated with high levels of water and in such slight pressure to a sealed vial by connecting a transfer tube from the
sample container to the vial.The sealed vial is allowed to cool prior to the
cases, the water phase may extract a significant amount of the methanol
and obscure the true total methanol content in the total sample determined addition of the toluene solvent as described in Section 12.
by this test method.
9. Preparation of Apparatus and Establishment of
8.2 Prior to analysis, allow the sample container as received
Conditions
to come to ambient temperature. Mix well the entire sample in
the sealed sample container. Waxy or other solid crudes, or 9.1 Assembly—Configure the GC system in a multidimen-
both,werenotevaluatedbythistestmethod.Oncemixedinthe sional configuration as described in 6.1. Configurations that
original sample container, immediately transfer the required were used successfully are described in 6.1 and may be used as
aliquot for weighing to avoid potential segregation of the a guideline. Connect the WCOT columns to the chromato-
methanol from the crude oil.Apoorly mixed sample may lead graphic system,
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7059 − 09 (Reapproved 2017) D7059 − 21
Standard Test Method for
Determination of Methanol in Crude Oils by
Multidimensional Gas Chromatography
This standard is issued under the fixed designation D7059; 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 Scope*
1.1 This test method covers the determination of methanol in crude oils by direct injection multidimensional gas chromatography
in the concentration range of 15 ppm (m/m) to 900 ppm (m/m). The pooled limit of quantification (PLOQ) is 15 ppm (m/m).
1.2 This test method is applicable only to crude oils containing less than or equal to 0.1 % (v/v) water.
1.3 This test method has not been tested with crude oil samples that are solid or waxy, or both, at ambient temperatures.
1.4 The values stated in SI units are to be regarded as standard. Alternate units, in common usage, are also provided to increase
clarity and aid the users of this test method.
1.5 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
D4006 Test Method for Water in Crude Oil by Distillation
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D4928 Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration
D6596 Practice for Ampulization and Storage of Gasoline and Related Hydrocarbon Materials
E355 Practice for Gas Chromatography Terms and Relationships
E594 Practice for Testing Flame Ionization Detectors Used in Gas or Supercritical Fluid Chromatography
3. Terminology
3.1 Definitions:
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of Subcommittee
D02.04.0L on Gas Chromatography Methods.
Current edition approved Oct. 1, 2017Dec. 1, 2021. Published November 2017December 2021. Originally approved in 2004. Last previous edition approved in 20132017
as D7059 – 09 (2013).(2017). DOI: 10.1520/D7059-09R17.10.1520/D7059-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7059 − 21
3.1.1 This test method makes reference to common gas chromatographic procedures, terms, and relationships. Detailed definitions
of these can be found in Practices E355 and E594, and Terminology D4175. Additional definitions and information pertinent to
this test method are listed below.
3.1.2 analytical column, n—porous layer open tubular (PLOT) column with a stationary phase selective for oxygenates.
Itoxygenates; it is used to resolve methanol from 1-propanol to provide accurate quantitative results.
3.1.3 cool-on-column injector, n—an injection port that allows controlled injection of the sample at a temperature close to or lower
than the boiling point of the solvent into the gas chromatographic column or a liner within the injection port connected to the
column.
3.1.3.1 Discussion—
After the injection, the injection port is heated at a fixed rate to a temperature sufficiently high enough to allow the transfer of
sample components of interest from the injection port to the part of the column located in the gas chromatograph (GC) oven.
3.1.4 electronic pressure control, n—electronic pneumatic control of carrier gas flows. Itflows; it can be flow or pressure
programmed to speed up elution of components.
3.1.5 low-volume connector, n—a special union for connecting two lengths of tubing 1.6-mm1.6 mm inside diameter and smaller;
sometimes referred to as a zero dead-volume union.
3.1.6 pre-column, n—a polydimethylsiloxane WCOT column used to isolate the methanol and 1-propanol and several light
hydrocarbons from the higher boiling portion of the crude oil sample for transfer to the analytical column for further separation
and quantification.
3.1.7 programmable temperature vaporizer (PTV), n—a temperature programmable injector similar to a cool-on-column injector
except that the sample is injected cool into a glass liner or insert instead of the WCOT (3.1.53.1.6) column and then the temperature
is programmed in a manner similar to the on-column injector.
3.1.7.1 Discussion—
The liner may be replaced, as necessary, to remove non-volatile materials. This injector may be operated in low split mode or direct
(no splitting) mode.
3.1.8 split/splitless injector, n—a heated capillary inlet or sample introduction system that allows controlled splitting of the injected
sample into two unequal portions, the smaller of which goes to the capillary column, and the greater to a vent.
3.1.8.1 Discussion—
When the vent is closed, the entire sample enters the capillary column and the inlet is operated as a splitless injector. When the
vent is open, the inlet is operated in the split mode and only a portion of the sample reaches the capillary column. The ratio of
the split between the capillary column and the vent is calculated as described in 3.1.7.13.1.8.1.
3.1.8.1 split ratio, n—in capillary gas chromatography, the ratio of the total flow of carrier gas to the sample inlet versus the
flow of the carrier gas to the capillary column, expressed by:
split ratio 5 ~S1C!/C (1)
where:
S = flow rate at the splitter vent, and
C = flow rate at the column outlet.
4. Summary of Test Method
4.1 An internal standard, 1-propanol, is added to the sample, which is then introduced into a gas chromatograph equipped with
two columns and a flow switching system between the two columns. The sample first passes through the polydimethylsiloxane
WCOT column that performs a pre-separation of the methanol and 1-propanol and eliminates unwanted hydrocarbons. The
methanol and 1-propanol are transferred to the analytical PLOT column for oxygenates. While the methanol and 1-propanol are
eluting from the analytical PLOT column for oxygenates, auxiliary carrier gas is used to elute higher boiling crude oil
hydrocarbons from the pre-column, either in the forward or backflush mode, to yield a stable baseline for the next analysis.
D7059 − 21
TABLE 1 Operating Conditions for Configuration A
Injector On-column. Temperature program: 50 °C (0.1 min) 30 °C ⁄min to 300 °C until end of oven program; 1.0 microlitre injected with autosampler
Oven 40 °C at 2 °C ⁄min to 70 °C (0 min); 4 °C ⁄min to 190 °C; 30 °C ⁄min to 250 °C (13.0 min)
temperature
program
Detectors Two flame ionization detectors (FID) at 325 °C. Hydrogen at 30 mL/min; air at 300 mL/min; helium make-up gas at 30 mL/min
Columns 60 m × 0.53 mm ID 5.0 μm film polydimethylsiloxane (pre-column)
10 m × 0.53 mm ID 10 μm film CP-Lowox
The two columns are coupled through a four-port Valco valve as shown in Fig. 1
When analyses are not being performed, the GC oven temperature should be kept at 250 °C, and the pre-column carrier head pressure kept at 60
psi. This procedure conditions the CP-Lowox column, which may trap carrier gas contaminants at the normal 40 °C starting temperature, and also
elutes residual heavy material from the pre-column.
Carrier Pre-column: 10 psi (20 min) 99 psi/min to 60 psi (until end of oven temperature program)
gas
CP-Lowox column flow: constant flow of 10 mL/min
Valve 260 °C
temperature
Valve 1. Valve on at 2.80 min and off at 4.00 min to transfer the methanol from the polydimethylsiloxane column to the CP-Lowox column
timing
2. Valve on at 6.80 min and off at 8.00 min to transfer the internal standard, 1-propanol
5. Significance and Use
5.1 Methanol is used in production of crude oil to prevent formation of gas hydrates. The presence of residual methanol in crude
oils can lead to costly problems in refinery operations.
6. Apparatus
6.1 Chromatograph—A multidimensional two-WCOT column gas chromatographic system, capable of adequately resolving
methanol and the 1-propanol internal standard and of eliminating hydrocarbon and other interferences, is required for this analysis.
Flow switching between the two specified WCOT columns may be accomplished by either using a valve or pneumatic (pressure)
switching to redirect flows. The unwanted higher boiling hydrocarbons may be removed from the pre-column either by forward
flush or backward flush. The system requires that carrier gas flow controllers must be capable of precise control for the typical
pressures required. Such flow controllers are available on gas chromatographs. The precision of this test method was obtained using
several instrument configurations described in 6.1.1 – 6.1.5. Other multidimensional configurations may be used, provided that
they meet all of the requirements of this test method.
6.1.1 Configuration A—Cool-on-column injection (no backflush of pre-column) with two separate selective heartcuts for the
methanol and 1-propanol internal standard. The chromatographic instrument can be operated at the approximate conditions given
in Table 1 and Fig. 1. Figs. 2-5 give chromatograms and a calibration curve.
6.1.2 Configuration B—Heated split injection with a single heartcut of methanol, 1-propanol and several C minus hydrocarbons
transferred to the PLOT column for oxygenates using a six-port valve. The pre-column, located in a separate auxiliary oven, is
backflushed to a vent using the six-port valve. Table 2 and Fig. 6 give details of the configuration.
6.1.3 Configuration C—Heated split injection with a single heartcut for the methanol, 1-propanol and C minus hydrocarbons,
followed by backflush of the pre-column through the injection port to remove the high boiling hydrocarbons retained on the
pre-column. The chromatographic instrument can be operated at the approximate conditions given in Table 3 and Fig. 7. The
pre-column is located in a separate auxiliary oven. Fig. 8 gives a chromatogram obtained with this system.
6.1.4 Configuration D—Direct PTV (no splitting) injection with a single heartcut for the methanol and the 1-propanol internal
standard and several low boiling hydrocarbons, followed by backflush of the pre-column through the injector to a vent by pressure
switching. Table 4 and Figs. 9 and 10 give flow configurations and operating conditions.
6.1.5 Configuration E—Split injection using pressure switching between the pre-column and the analytical column. After transfer
to the analytical column, pressure is reduced at the inlet and the pre-column is backflushed to remove high boiling crude
components. Table 5 and Fig. 11 give the flow configurations and operating conditions.
6.2 Detector—At least one, main flame ionization detector (FID) is required. In a two FID detector configuration, the optional
second detector is used to monitor the pre-column elution and aids in setting heartcut or transfer times for the methanol and
D7059 − 21
FIG. 1 Valve Diagram for Configuration A
NOTE 1—Two separate injections: TOP/ methanol/1-propanol internal standard solution and BOTTOM/crude oil only.
FIG. 2 Relative Retention Windows on Polydimethylsiloxane Pre-column in Configuration A Using Monitor FID
1-propanol. The main detector’s response, proportional to the concentrations of the methanol and 1-propanol, is recorded; the peak
areas are measured; and the concentration of methanol is calculated with reference to the 1-propanol internal standard and a
calibration curve.
6.3 Valve or Pneumatic (pressure) Switching, for systems using valve switching (for example, Configurations A, B in 6.1), a high
temperature and low volume valve, located within the gas chromatographic column oven or in a separate oven, capable of
performing the functions described in 6.1. The valve connections shall not contribute significantly to chromatographic
deterioration. Refer to Fig. 2, Fig. 3, and Fig. 8 for compound peak performance, manufacturer’s guidelines and examples given
in 6.1 as a guide in assembling the GC system. For example, Valco Model No. A 4C10WP, 1.6-mm1.6 mm ( ⁄16-in.) in.) fittings
was used in Configuration A (6.1). Other equivalent valves may be used. Alternatively, pneumatic or pressure switching may be
used instead of a valve (for example, Configurations C, D, and E in 6.1).
6.3.1 When using valve switching for heart-cutting, an automatic valve-switching device must be used to ensure repeatable
switching times. Such a device must be synchronized with injection and data collection times. For the pressure switching
(Configurations C, D, and E) approach, automatic precise and stable pressure control must be used to yield stable retention times.
6.4 Injection System—Several sample injection systems have been used successfully with the configurations in 6.1. Generally,
splitless or direct injection types allow detection of lower levels (1 ppm or less) of methanol. The splitless or direct injection
systems include: (A) a cool-on-column temperature programmable vaporizer, and appropriate autosampler to allow such injections
(Configuration A in 6.1); and (B) PTV (Configuration D in 6.1). Alternatively, heated, splitting type injectors may be used with
D7059 − 21
FIG. 3 Chromatogram of Methanol and 1-propanol Internal Standard with Configuration A
FIG. 4 Chromatogram of 5 ppm Methanol with Configuration A
low split ratios (Configurations B, C, and E in 6.1). The splitting type of injection generally is applicable for concentrations greater
than or equal to 2 ppm methanol. With splitting type injectors, the replaceable glass deactivated liner (single-taper style with
deactivated glass wool at the bottom to retain unvaporized components) was used successfully (for example, as in Configuration
C in 6.1).
6.4.1 Automatic microlitre syringe injectors must be used for introducing representative samples into the GC inlet. Cool-on-
column automated injectors may need special syringe needles, and so forth. Follow the manufacturer’s instructions.
6.5 Data Presentation or Calculation:
6.5.1 Recorder—A data system is used for recording and evaluating the chromatograms.
6.5.2 Integrator or Computer—A computer or electronic integrator is used to obtain peak areas.
D7059 − 21
FIG. 5 Calibration Curve of 1 to 1000 ppm Methanol with Configuration A
TABLE 2 Operating Conditions for Configuration B
Column 1 (pre-column) 10 m × 0.53 mm
polydimethylsiloxane (5 μm
film)
Column 2 10 m × 0.53 mm CP-Lowox
(10 μm film)
Injector type Capillary Split
Injector split ratio 5:1
Injection size 2 μL (with autosampler)
Injector temperature 350 °C
Pre-column oven 300 °C
Detector temperature 300 °C
Oven temperature 125 °C (2 min) 20 °C ⁄min to
300 °C (4.25 min)
Carrier gas Helium
Carrier gas flow rate 10 mL/min
6.6 Pre-column WCOT, containing a 5 μm film thickness of cross-linked polymethyldisiloxane, or equivalent, to meet all of the
requirements in this test method. This column performs a pre-separation of the methanol and 1-propanol internal standard from
hydrocarbons in the same boiling point range. The column shall perform at the same temperature as required for the column in
6.7, except if located in a separate auxiliary oven. The configurations in 6.1 give examples of columns used successfully.
6.7 Analytical Column, a PLOT column for oxygenates, 10 m 10 m long by 0.53 mm 0.53 mm I.D., with a stationary phase coated
onto a fused silica capillary or equivalent. At a minimum, the column shall have sufficient retention for methanol that it elutes after
n-tridecane (retention index >1300) at 150 °C, and have sufficient efficiency and capacity to resolve methanol from 1-propanol to
provide accurate quantitative results. Ensure that acetone does not interfere with the methanol analysis by analyzing a 1000 ppm
mixture of acetone in crude oil containing the 1-propanol internal standard after the system has been optimized.
7. Reagents and Materials
7.1 Carrier Gas—Helium and ultrapure nitrogen have been used successfully. The minimum purity of the carrier gas used must
be 99.95 mole %. Oxygen scrubbers are recommended to safeguard the WCOT columns.
D7059 − 21
FIG. 6 Valve Diagram for Configuration B
TABLE 3 Configuration C (Pressure Switching and Backflush of Pre-column) Approximate Operating Conditions
(Pre-column in Isothermal Second Oven)
Injector Split/splitless. 4:1 split ratio; 325 °C; 1.0 microlitre injected with autosampler
Oven temperature program (contains CP-Lowox WCOT column) 125 °C (3 min.) 20 °C ⁄min. to 300 °C (10 min)
Prefac oven (contains pre-column) temp 300 °C
Detectors Single flame ionization detector (FID) at 350 °C. Hydrogen at 35 mL/min; air at
350 mL/min; make-up gas at 20 mL/min
Columns 10 m × 0.53 mm ID 5.0 μm film polydimethylsiloxane (pre-column)
10 m × 0.53 mm ID 10 μm film CP-Lowox
The two columns are coupled through a pressure switching coupling as shown in
Fig. 6
Carrier gas Helium at a linear velocity of 120 cm/s
Pre-column backflush timing 15 s to 20 s
7.2 Methanol, >99.9 % pure (Warning—Flammable; vapor harmful).
D7059 − 21
FIG. 7 Schematic of Configuration C (Table 3)
7.3 1-Propanol, >99.9 % pure, and containing <500 ppm methanol (Warning—Flammable; vapor harmful).
7.4 Toluene, >99.9 % pure, and containing <0.5 ppm methanol (Warning—Flammable; vapor harmful).
7.5 Quality Control Standards, containing known concentrations of methanol in crude oils (Warning—Flammable; vapor
harmful).
8. Sampling
8.1 Ensure that the sample is representative of the crude oil from which it is taken. The use of multiple samples which are mixed
D7059 − 21
FIG. 8 Chromatogram Obtained with Configuration C
TABLE 4 Configuration D (Pressure Switching and Backflush of Pre-column) Approximate Operating Conditions
(Pre-column and Polar WCOT in Same Oven)
Gas chromatography (GC):
Pre-column/analytical WCOT’s CP SIL 5CB 10 m × 0.53 mm ID df = 5.0 μm and CP-Lowox 10 m ×
0.53 mm ID
Injector type PTV direct injection (packed columns equipped with adapter for
installing 0.53 mm ID wide bore WCOT)
Injector split ratio Direct injection: no split
Injection size 1.0 μL
Injector temperature 250 °C isothermal
Oven temperature 100 °C (2.5 min); 40 °C ⁄min to 290 °C (25.0 min)
Carrier gas Nitrogen
Carrier gas flow rates Flow at the detector in forward flush 15 mL/min. Flow at the detector
in backflush 8 mL/min
or composite sampling is recommended when sampling from a large source of the crude oil. Follow the recommendations of
Practice D4057, or its equivalent, when obtaining samples from bulk storage or pipelines. The use of epoxy-lined cans is
recommended for storage or shipping, or both, of the sample.
D7059 − 21
NOTE 1—Current position: forward flush for heartcutting from pre-column to PLOT column for oxygenates (FID B not used).
NOTE 2—CG = carrier gas. The dotted line indicates the carrier gas flow path for foreflush and backflush.
FIG. 9 Flow Scheme of Configuration D
8.1.1 Methanol content by this test method must be determined on a sample containing less than or equal to 0.1 % (v ⁄v) water.
All of the crude oil samples used in the cooperative study to develop the precision of this test method contained less than or equal
to 0.1 % (v/v) water. Determine the water content using Test Method D4928, Test Method D4006, or equivalent.
NOTE 1—The methanol content in crude oils is the combined methanol content in the crude oil and, if present, in the associated water. It is known that
some crude oils are associated with high levels of water and in such cases, the water phase may extract a significant amount of the methanol and obscure
the true total methanol content in the total sample determined by this test method.
8.2 Prior to analysis, allow the sample container as received to come to ambient temperature. Mix well the entire sample in the
sealed sample container. Waxy or other solid crudes, or both, were not evaluated by this test method. Once mixed in the original
D7059 − 21
NOTE 1—Current position: Backflush (FID B not used).
NOTE 2—CG = carrier gas. The dotted line indicates the carrier gas flow path for foreflush and backflush.
FIG. 10 Flow Scheme for Configuration D
TABLE 5 Configuration E (Pressure Switching and Backflush of Pre-column Through Injection Port) Approximate Operating Conditions
(Pre-column and Polar WCOT in Same Oven)
Gas chromatography (GC):
Column 1/Column 2 Column 1: polydimethylsiloxane, 5 μm, 10 m × 0.53 mm
Column 2: CP-Lowox, 10 m × 0.53 mm
Injector type Split/splitless used in split mode; the inlet liner is a 4 mm liner with a
taper at the bottom and glass wool in the center of the liner
Injector split ratio 7:1
Injection size 1 μL
Injector temperature 325 °C
Oven temperature 150 °C (3 min); 20 °C ⁄min to 300 °C (5 min)
C
...