ASTM D7266-13 - 1.2.2013
 
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.

 
1. 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 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.

TABLE 1 Impurities Known or Suggested to be Present in Commercial Cyclohexane

 C4

(1) n-butane

(2) isobutene

 C5

(3) n-pentane

(4) isopentane

(5) cyclopentane

 C6

(6) n-hexane

(7) 2-methylpentane

(8) 3-methylpentane

(9) methylcyclopentane

(10) benzene

(11) cyclohexene

(12) 2,2-dimethylbutane

(13) 2,3-dimethylbutane

 C7

(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

 C8

(32) iso-octane

(33) p-xylene

 C9

(34) isopropylcylohexane


1.3 The limit of detection is 1 mg/kg.

1.4 In 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.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.

 
2. Referenced Documents

E1510-95(2021)

Standard Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs

E691-23

Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

E355-96(2021)e1

Standard Practice for Gas Chromatography Terms and Relationships (Includes all amendments and changes 4/28/2021).

D3437-15(2022)

Standard Practice for Sampling and Handling Liquid Cyclic Products

D4307-17(2021)

Standard Practice for Preparation of Liquid Blends for Use as Analytical Standards

D4790-25

Standard Terminology of Aromatic Hydrocarbons and Related Chemicals

D6809-24

Standard Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials

E29-22

Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications