ASTM D7266-23

Standard Test Method for Analysis of Cyclohexane by Gas Chromatography (External Standard)

SIGNIFICANCE AND USE
5.1 This test method is suitable for setting specifications on the materials referenced in Table 1 and for use as an internal quality control tool where cyclohexane is produced or is used in a manufacturing process. It may also be used in development or research work involving cyclohexane.  
5.2 This test method is useful in determining the purity of cyclohexane with normal impurities present. If extremely high boiling or unusual impurities are present in the cyclohexane, this test method would not necessarily detect them and the purity calculation would be erroneous.
SCOPE
1.1 This test method covers the determination of the purity of cyclohexane by gas chromatography.  
1.2 This test method is applicable to the measurement of impurities in Table 1. This test method is applicable to samples with concentrations to 400 mg/kg, but may be applicable to a wider range. The limit of detection (LOD) is 1 mg/kg and the limit of quantitation (LOQ) is 3 mg/kg for benzene.
Note 1: The LOD and LOQ were calculated from the ILS data for benzene.  
1.3 The following applies for the purposes of determining the conformance of the test results using this test method to applicable specifications, results shall be rounded off in accordance with the rounding-off method of Practice E29.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
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. For specific hazard statements, see Section 8.  
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-Jun-2023
• ICS: 71.080.10 - Aliphatic hydrocarbons
• Technical Committee: D16 - Aromatic, Industrial, Specialty and Related Chemicals
• Drafting Committee: D16.01 - Benzene, Toluene, Xylenes, Cyclohexane and Their Derivatives

Relations

• Refers: ASTM D6809-02(2016) - Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
• Effective Date: 01-Nov-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 D4790-14 - Standard Terminology of Aromatic Hydrocarbons and Related Chemicals
• Effective Date: 01-Jul-2014
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM D4790-11 - Standard Terminology of Aromatic Hydrocarbons and Related Chemicals
• Effective Date: 01-Feb-2011
• Refers: ASTM D3437-11 - Standard Practice for Sampling and Handling Liquid Cyclic Products
• Effective Date: 01-Jan-2011
• Refers: ASTM D3437-10 - Standard Practice for Sampling and Handling Liquid Cyclic Products
• 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 E29-08 - Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
• Effective Date: 01-Oct-2008
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM D3437-08 - Standard Practice for Sampling and Handling Liquid Cyclic Products
• Effective Date: 01-Jun-2008
• Refers: ASTM D4790-07 - Standard Terminology of Aromatic Hydrocarbons and Related Chemicals
• Effective Date: 15-Jul-2007
• Refers: ASTM D6809-02(2007) - Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
• Effective Date: 01-Jun-2007
• Refers: ASTM E355-96(2007) - Standard Practice for Gas Chromatography Terms and Relationships
• Effective Date: 01-Mar-2007

Overview

ASTM D7266-23 is an international standard test method developed by ASTM International for the analysis of cyclohexane purity using gas chromatography with an external standard calibration. This test method is essential for quality control, specification setting, and research purposes in industries where cyclohexane is produced or used. The standard outlines a systematic approach to measure cyclohexane and its typical impurities at trace levels, helping ensure consistent product quality and regulatory compliance.

Key Topics

Purpose and Significance

• Establishes a reliable method for determining the purity of cyclohexane using gas chromatography.
• Supports both internal quality control and contractual specification in industrial manufacturing and research settings.
• Allows for the quantification of common hydrocarbon impurities associated with cyclohexane.

Scope of Applicability

• Suitable for cyclohexane samples with impurity concentrations up to 400 mg/kg.
• Impurities covered include a wide range of aliphatic and aromatic hydrocarbons, such as n-hexane, methylcyclopentane, benzene, toluene, p-xylene, and others often present in commercial cyclohexane.
• Offers a limit of detection (LOD) of 1 mg/kg and a limit of quantitation (LOQ) of 3 mg/kg specifically for benzene, ensuring high sensitivity for critical contaminants.

Gas Chromatography Method

• Relies on a gas chromatograph equipped with a flame ionization detector for sample analysis.
• Utilizes external standard calibration, where known concentrations of impurities are used to establish accurate quantification.
• Requires the use of electronic data integration or chromatographic data systems for measuring impurity concentrations.
• Purity is calculated by subtracting the total impurity content from 100%, with individual impurities reported in mg/kg and overall cyclohexane content in weight percent.

Precision and Quality Assurance

• Includes detailed guidelines for calibration, data reporting, and method validation.
• Encourages interlaboratory studies and the use of quality control samples to ensure reproducibility of results among laboratories.
• Stipulates conformance to Practice E29 for significant digits in test data.

Applications

Industrial Quality Control

• Used by cyclohexane manufacturers and downstream users to monitor product purity and support internal quality assurance programs.
• Necessary for compliance with contractual specifications where precise composition is required.

Regulatory and Environmental Compliance

• Assists in verifying that cyclohexane meets safety and environmental standards by detecting and quantifying hazardous impurities like benzene and toluene.
• Referenced for regulatory reporting and documentation where accurate purity counts, such as OSHA-required hazard assessments.

Research and Development

• Supports laboratories and R&D teams in characterizing cyclohexane samples during process development, optimization, or analytical method validation.

Related Standards

For best practices, laboratories applying ASTM D7266-23 often use related ASTM standards, including:

• ASTM D3437: Practice for Sampling and Handling Liquid Cyclic Products.
• ASTM D4307: Practice for Preparation of Liquid Blends for Use as Analytical Standards.
• ASTM D6809: Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials.
• ASTM E29: Practice for Using Significant Digits in Test Data.
• ASTM E355: Practice for Gas Chromatography Terms and Relationships.
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.
• ASTM E1510: Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs.

Adopting ASTM D7266-23, alongside these related standards, provides a comprehensive framework for analytical testing, ensuring high reliability and comparability of cyclohexane purity data in industrial, regulatory, and research contexts.

Keywords: ASTM D7266, cyclohexane analysis, gas chromatography, external standard, purity determination, impurities in cyclohexane, industrial quality control, benzene detection, hydrocarbon analysis.

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: D7266 − 23
Standard Test Method for
Analysis of Cyclohexane by Gas Chromatography (External
Standard)
This standard is issued under the fixed designation D7266; 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
2.1 ASTM Standards:
1.1 This test method covers the determination of the purity
of cyclohexane by gas chromatography. D3437 Practice for Sampling and Handling Liquid Cyclic
Products
1.2 This test method is applicable to the measurement of
D4307 Practice for Preparation of Liquid Blends for Use as
impurities in Table 1. This test method is applicable to samples
Analytical Standards
with concentrations to 400 mg/kg, but may be applicable to a
D4790 Terminology of Aromatic Hydrocarbons and Related
wider range. The limit of detection (LOD) is 1 mg/kg and the
Chemicals
limit of quantitation (LOQ) is 3 mg/kg for benzene.
D6809 Guide for Quality Control and Quality Assurance
NOTE 1—The LOD and LOQ were calculated from the ILS data for
Procedures for Aromatic Hydrocarbons and Related Ma-
benzene.
terials
1.3 The following applies for the purposes of determining E29 Practice for Using Significant Digits in Test Data to
the conformance of the test results using this test method to Determine Conformance with Specifications
applicable specifications, results shall be rounded off in accor- E355 Practice for Gas Chromatography Terms and Relation-
dance with the rounding-off method of Practice E29. ships
E691 Practice for Conducting an Interlaboratory Study to
1.4 The values stated in SI units are to be regarded as
Determine the Precision of a Test Method
standard. No other units of measurement are included in this
E1510 Practice for Installing Fused Silica Open Tubular
standard.
Capillary Columns in Gas Chromatographs
1.5 This standard does not purport to address all of the
2.2 Other Document:
safety concerns, if any, associated with its use. It is the
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
responsibility of the user of this standard to establish appro-
1910.1200
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3. Terminology
For specific hazard statements, see Section 8.
3.1 See Terminology D4790 for definitions of terms used in
1.6 This international standard was developed in accor-
this test method.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
4. Summary of Test Method
Development of International Standards, Guides and Recom-
4.1 Cyclohexane is analyzed using a gas chromatograph
mendations issued by the World Trade Organization Technical
(GC) equipped with a flame ionization detector (FID). A
Barriers to Trade (TBT) Committee.
precisely repeatable volume of the sample to be analyzed is
1 2
This test method is under the jurisdiction of ASTM Committee D16 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsi- contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
bility of Subcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Standards volume information, refer to the standard’s Document Summary page on
Their Derivatives. the ASTM website.
Current edition approved July 1, 2023. Published July 2023. Originally approved Available from U.S. Government Printing Office Superintendent of Documents,
ε1
in 2007. Last previous edition approved in 2018 as D7266 – 13 (2018) . DOI: 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
10.1520/D7266-23. www.access.gpo.gov.
*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
D7266 − 23
TABLE 1 Impurities Known or Suggested to be Present in TABLE 2 Recommended Operating Conditions
Commercial Cyclohexane
Detector flame ionization
Injection Port capillary splitter
C
Column A:
(1) n-butane
Tubing fused silica
(2) isobutene
Stationary phase bonded and crosslinked
C
100 % dimethylpolysiloxane
(3) n-pentane
Film thickness, μm 0.5
(4) isopentane
Length, m 100
(5) cyclopentane
Diameter, mm 0.25
C
Temperatures:
(6) n-hexane
Injector, °C 230
(7) 2-methylpentane
Detector, °C 250
(8) 3-methylpentane
Oven, °C 32 hold for 12 min
(9) methylcyclopentane
Ramp 1 = 8 °C ⁄min to
(10) benzene
64 °C, hold for 10 min
(11) cyclohexene
Ramp 2 = 10 °C ⁄min to
(12) 2,2-dimethylbutane
200 °C, hold for 5 min
(13) 2,3-dimethylbutane
Carrier gas Hydrogen
C
Flow rate, mls/min 3
(14) 3,3-dimethylpentane
Split ratio 100:1
(15) 2,2-dimethylpentane
Sample size, μl 1.0
(16) 2,3-dimethylpentane
(17) 2,4-dimethylpentane
(18) 1,1-dimethylcyclopentane
(19) trans-1,3-dimethylcyclopentane
(20) trans-1,2-dimethylcyclopentane
obtain a minimum peak height response for 1 mg/kg benzene
(21) cis-1,2-dimethylcyclopentane
of twice the height of the signal background noise.
(22) 2,2-dimethylcyclopentane
(23) 2,4-dimethylcyclopentane
6.2 Columns—The choice of column is based on resolution
(24) cis-1,3-dimethylcyclopentane
requirements. Any column may be used that is capable of
(25) ethylcyclopentane
resolving all significant impurities from cyclohexane. The
(26) methylcyclohexane
(27) 3-ethylpentane
column and conditions described in Table 2 has been used
(28) 3-methylhexane
successfully and shall be used as a referee in cases of dispute.
(29) 2-methylhexane
(30) n-heptane
6.3 Chromatographic data systems are preferred but elec-
(31) toluene
tronic integration may be used if the user can demonstrate that
C
(32) iso-octane
the results are consistent with the precision statement.
(33) p-xylene
6.4 Injector—An autoinjector is required.
C
(34) isopropylcylohexane
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
injected onto the gas chromatograph. The peak areas of the
all reagents shall conform to the specifications of the Commit-
impurities are measured and converted to concentrations via an
tee on Analytical Reagents of the American Chemical Society,
external standard methodology. Purity by GC (the cyclohexane
where such specifications are available. Other grades may be
content) is calculated by subtracting the sum of the impurities
used, provided it is first ascertained that the reagent is of
from 100.00. Individual impurities are reported in mg/kg. The
sufficiently high purity to permit its use without lessening the
cyclohexane purity is reported in weight percent.
accuracy of the determination.
7.2 Instrument Setup Check Sample:
5. Significance and Use
7.2.1 Prepare a synthetic mixture of high purity cyclo-
5.1 This test method is suitable for setting specifications on
hexane containing impurities at concentrations representative
the materials referenced in Table 1 and for use as an internal
of those expected in the samples to be analyzed in accordance
quality control tool where cyclohexane is produced or is used
with Practice D4307. The weight of each hydrocarbon impurity
in a manufacturing process. It may also be used in development
must be measured to the nearest 0.1 mg. Because the avail-
or research work involving cyclohexane.
ability of stock cyclohexane with a purity higher than 99.97 %
is problematic, the method of standard additions may be
5.2 This test method is useful in determining the purity of
required for impurities such as methycyclohexane and
cyclohexane with normal impurities present. If extremely high
methylcyclopentane, as well as for a number of the other
boiling or unusual impurities are present in the cyclohexane,
impurities listed in Table 1 that are commonly present.
this test method would not necessarily detect them and the
purity calculation would be erroneous.
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
6. Apparatus
Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by the American Chemical
6.1 Gas Chromatograph—Any instrument having a flame
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
ionization detector that can be operated at the conditions given
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
in Table 2. The system should have sufficient sensitivity to copeial Convention, Inc. (USPC), Rockville, MD.
D7266 − 23
7.2.1.1 Include sufficient n-octane so the standard contains tions. The user must conduct the necessary evaluation to
approximately 2 mg/kg n-octane. determine that equivalent results are obtained. Carrier, makeup,
7.2.1.2 Below are impurities that may be included. and detector gases (except air) 99.999 % minimum purity.
Oxygen in carrier gas less than 1 ppm, less than 0.5 ppm is
isopentane CAS 78-78-4
n-pentane CAS 109-66-0
preferred. Purify carrier, makeup, and detector gases to remove
2,2-dimethylbutane CAS 75-83-2
oxygen, water, and hydrocarbons. Purify air to remove hydro-
2,3-dimethylbutane CAS 79-29-8
carbons and water, and the air used for an FID should contain
cyclopentane CAS 287-92-3
2-methylpentane CAS 107-83-5
less than 0.1 ppm total hydrocarbons.
3-methylpentane CAS 96-14-0
n-hexane CAS 110-54-3
8. Hazards
2,2-dimethylpentane CAS 590-35-2
methylcyclopentane CAS 96-37-7
8.1 Consult current OSHA regulations, suppliers’ Safety
2,4-dimethylpentane CAS 108-08-7
Data Sheets, and local regulations for all materials listed in this
benzene CAS 71-43-2
...

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.
´1
Designation: D7266 − 13 (Reapproved 2018) D7266 − 23
Standard Test Method for
Analysis of Cyclohexane by Gas Chromatography (External
Standard)
This standard is issued under the fixed designation D7266; 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.
ε NOTE—Section 8 was editorially corrected in January 2018.
1. Scope Scope*
1.1 This test method covers the determination of the purity of cyclohexane by gas chromatography. Calibration of the gas
chromatography system is done by the external standard calibration technique.
1.2 This test method has been found is applicable to the measurement of impurities such as those found in Table 1, which are
impurities that may be found in cyclohexane. The impurities can be analyzed over a range of 3 to 200 mg/kg by this method, but
may be applicable to a wider range. This test method is applicable to samples with concentrations to 400 mg/kg, but may be
applicable to a wider range. The limit of detection (LOD) is 1 mg/kg and the limit of quantitation (LOQ) is 3 mg/kg for benzene.
NOTE 1—The LOD and LOQ were calculated from the ILS data for benzene.
1.3 The limit of detection is 1 mg/kg.
1.3 In The following applies for the purposes of determining the conformance of the test results using this test method to
applicable specifications, results shall be rounded off in accordance with the rounding-off method of Practice E29.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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. For specific hazard statements, see Section 8.
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:
D3437 Practice for Sampling and Handling Liquid Cyclic Products
This test method is under the jurisdiction of ASTM Committee D16 on Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsibility of
Subcommittee D16.01 on Benzene, Toluene, Xylenes, Cyclohexane and Their Derivatives.
Current edition approved Jan. 1, 2018July 1, 2023. Published January 2018July 2023. Originally approved in 2007. Last previous edition approved in 20132018 as D7266
ε1
– 13 (2018) . DOI: 10.1520/D7266-13R18E01.10.1520/D7266-23.
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
D7266 − 23
TABLE 1 Impurities Known or Suggested to be Present in
Commercial Cyclohexane
C
(1) n-butane
(2) isobutene
C
(3) n-pentane
(4) isopentane
(5) cyclopentane
C
(6) n-hexane
(7) 2-methylpentane
(8) 3-methylpentane
(9) methylcyclopentane
(10) benzene
(11) cyclohexene
(12) 2,2-dimethylbutane
(13) 2,3-dimethylbutane
C
(14) 3,3-dimethylpentane
(15) 2,2-dimethylpentane
(16) 2,3-dimethylpentane
(17) 2,4-dimethylpentane
(18) 1,1-dimethylcyclopentane
(19) trans-1,3-dimethylcyclopentane
(20) trans-1,2-dimethylcyclopentane
(21) cis-1,2-dimethylcyclopentane
(22) 2,2-dimethylcyclopentane
(23) 2,4-dimethylcyclopentane
(24) cis-1,3-dimethylcyclopentane
(25) ethylcyclopentane
(26) methylcyclohexane
(27) 3-ethylpentane
(28) 3-methylhexane
(29) 2-methylhexane
(30) n-heptane
(31) toluene
C
(32) iso-octane
(33) p-xylene
C
(34) isopropylcylohexane
D4307 Practice for Preparation of Liquid Blends for Use as Analytical Standards
D4790 Terminology of Aromatic Hydrocarbons and Related Chemicals
D6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E355 Practice for Gas Chromatography Terms and Relationships
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1510 Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs
2.2 Other Document:
OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.1200
3. Terminology
3.1 See Terminology D4790 for definitions of terms used in this test method.
4. Summary of Test Method
4.1 Cyclohexane is analyzed using a gas chromatograph (GC) equipped with a flame ionization detector (FID). A precisely
repeatable volume of the sample to be analyzed is injected onto the gas chromatograph. The peak areas of the impurities are
measured and converted to concentrations via an external standard methodology. Purity by GC (the cyclohexane content) is
calculated by subtracting the sum of the impurities from 100.00. Individual impurities are reported in mg/kg. The cyclohexane
purity is reported in weight percent.
Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
www.access.gpo.gov.
D7266 − 23
5. Significance and Use
5.1 This test method is suitable for setting specifications on the materials referenced in Table 1 and for use as an internal quality
control tool where cyclohexane is produced or is used in a manufacturing process. It may also be used in development or research
work involving cyclohexane.
5.2 This test method is useful in determining the purity of cyclohexane with normal impurities present. If extremely high boiling
or unusual impurities are present in the cyclohexane, this test method would not necessarily detect them and the purity calculation
would be erroneous.
6. Apparatus
6.1 Gas Chromatograph—Any instrument having a flame ionization detector that can be operated at the conditions given in Table
2. The system should have sufficient sensitivity to obtain a minimum peak height response for 1 mg/kg benzene of twice the height
of the signal background noise.
6.2 Columns—The choice of column is based on resolution requirements. Any column may be used that is capable of resolving
all significant impurities from cyclohexane. The column described and conditions described in Table 2 has been used
successfully.successfully and shall be used as a referee in cases of dispute.
6.3 Recorder—Electronic integration is required.Chromatographic data systems are preferred but electronic integration may be
used if the user can demonstrate that the results are consistent with the precision statement.
6.4 Injector—The specimen must be precisely and repeatably injected into the gas chromatograph. An automatic sample injection
device is highly recommended. Manual injection can be employed if the precision stated in Tables 3–7 can be reliably and
consistently satisfied.An autoinjector is required.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
TABLE 2 Instrumental ParametersRecommended Operating
Conditions
Detector flame ionization
Injection Port capillary splitter
Column A:
Tubing fused silica
Stationary phase bonded and crosslinked
100 % dimethylpolysiloxane
Film thickness, μm 0.5
Length, m 100
Diameter, mm 0.25
Temperatures:
Injector, °C 230
Detector, °C 250
Oven, °C 32 hold for 12 min
Ramp 1 = 8°C/min to 64°C,
hold for 10 min
Ramp 1 = 8 °C ⁄min to
64 °C, hold for 10 min
Ramp 2 = 10°C/min to
200°C, hold for 5 min
Ramp 2 = 10 °C ⁄min to
200 °C, hold for 5 min
Carrier gas Hydrogen
Flow rate, mls/min 3
Split ratio 100:1
Sample size, μl 1.0
D7266 − 23
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
7.2 Instrument Setup Check Sample:
7.2.1 Prepare a synthetic mixture of high purity cyclohexane containing impurities at concentrations representative of those
expected in the samples to be analyzed in accordance with Practice D4307. The weight of each hydrocarbon impurity must be
measured to the nearest 0.1 mg. Because the availability of stock cyclohexane with a purity higher than 99.97 % is problematic,
the method of standard additions may be required for impurities such as methycyclohexane and methylcyclopentane, as well as
for a number of the other impurities listed in Table 1 that are commonly present.
7.2.1.1 Include sufficient n-octane so the standard contains approximately 2 mg/kg n-octane.
7.2.1.2 Below are impurities that may be included.
isopentane CAS 78-78-4
n-pentane CAS 109-66-0
2,2-dimethylbutane CAS 75-83-2
2,3-dimethylbutane CAS 79-29-8
cyclopentane CAS 287-92-3
2-methylpentane CAS 107-83-5
3-methylpentane CAS 96-14-0
n-hexane CAS 110-54-3
2,2-dimethylpentane CAS 590-35-2
methylcyclopentane CAS 96-37-7
2,4-dimethylpentane CAS 108-08-7
benzene CAS 71-43-2
2,3-dimethylpentane CAS 565-59-3
Iso-octane CAS 540-84-1
n-heptane CAS 142-82-5
methylcyclohexane CAS 108-87-2
ethylcyclopentane CAS 1640-89-7
Toluene CAS108-88-3
p-xylene CAS 106-42-3
isopropylcylohexane CAS 696-29-7
1,1-dimethylcyclopentane CAS 1638-26-2
trans-1,3-dimethylcyclopentane CAS 1759-58-6
trans-1,2 dimethylcyclopentane CAS 822-50-4
cis-1,2-dimethylcyclopentane CAS 1192-18-3
cis-1,3-dimethylcyclopentane CAS 2532-58-3
3-ethylpentane CAS 617-78-7
3-methylhexane CAS 589-34-4
2-methylhexane CAS 591-76-4
7.2.1.3 The purpose of this setup sample is to calibrate the instrument, determine retention times of impurities, and determine if
setup has the required sensitivity.
7.3 Gases—Helium, hydrogen, nitrogen, or other as carrier. carrier are permitted. Hydrogen carrier gas was used to develop this
standard. Use of helium or nitrogen require different conditions. The user must conduct the necessary evaluation to determine that
equivalent results are obtained. Carrier, makeup, and detector gases (except air
...