ASTMD6526-10甲苯纯度分析方法

Designation:D6526–10

Standard Test Method for

Analysis of Toluene by Capillary Column Gas Chromatography 1

This standard is issued under the fixeddesignation D6526; 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*

1.1This test method covers the determination of hydrocar-bon impurities typically found in, and the purity of, samples containing 98wt %and greater toluene. This test method is applicable to impurity concentrations in the range of 0.0005to 1.6wt %.

1.2Monocyclic aromatic hydrocarbons containing 6through 8carbon atoms, cumene, 1,4–dioxane,and nonaro-matic aliphatic hydrocarbons containing up to 12carbon atoms can be detected by this test method. The nonaromatic com-pounds are determined as a composite.

1.3The following applies to all specifiedlimits in this test method:for purposes of determining conformance with this test method, an observed value or a calculated value shall be rounded off “tothe nearest unit”in the last right-hand digit used in expressing the specificationlimit, in accordance with the rounding-off method of Practice E29.

1.4The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.5This 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 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specifichazard statements, see Section 9.

2. Referenced Documents 2.1ASTM Standards:2

D3437Practice for Sampling and Handling Liquid Cyclic Products

This test method is under the jurisdiction of ASTM Committee D16on Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of Subcommittee D16.01on Benzene, Toluene, Xylenes, Cyclohexane and Their Derivatives.

Current edition approved June 1, 2010. Published June 2010. Originally approved in 2000. Last previous edition approved in 2003as D6526-03´1. DOI:10.1520/D6526-10.2

For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [email protected] Annual Book of ASTM Standards volume information, refer to the standard’sDocument Summary page on the ASTM website.

1

D4790Terminology of Aromatic Hydrocarbons and Related Chemicals

D6809Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Ma-terials

E29Practice for Using SignificantDigits in Test Data to Determine Conformance with Specifications

E355Practice for Gas Chromatography Terms and Rela-tionships

E691Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

E1510Practice for Installing Fused Silica Open Tubular Capillary Columns in Gas Chromatographs 2.2Other Document:

OSHA Regulations, 29CFR paragraphs 1910.1000and 1910.120033. Terminology

3.1See Terminology D4790for definitionsof terms used in this test method.

4. Summary of Test Method

4.1A portion of the sample is injected into a gas chromato-graph using a microlitre syringe at the specifiedconditions of the test method. The toluene and other components are separated as they are transported through the column by an inert carrier gas. The components in the effluent are measured by a flameionization detector (FID).The area of the impurity peaks and toluene are electronically integrated. The peak areas are corrected with effective carbon number (ECN)4response factors and normalized to 100.0000%.

5. Significanceand Use

5.1This test method is suitable for determining the concen-trations of known impurities in refinedtoluene and for use as

Available from U.S. Government Printing Office Superintendent of Documents, 732N. Capitol St., NW, Mail Stop:SDE, Washington, DC 20401, http://www.access.gpo.gov. 4

Scanlon, J. T., and Willis, D. E., “Calculationof Ionization Detector Relative Response Factors Using the Effective Carbon Number Concept,”Journal of Chromatographic Science , V ol 35, August, 1985, pp. 333-339.

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*ASummary of Changes section appears at the end of this standard.

Copyright (C)ASTM International. 100Barr Harbor Dr. P.O. box C-700West Conshohocken, Pennsylvania 19428-2959, United States

D6526–10

the specificationsof the Committee on Analytical Reagents of the American Chemical Society, 5where such specificationsare available, unless otherwise indicated. Other grades may be used, provided it is firstascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.

8.2Carrier Gas —Helium,99.99mole %minimum, is rec-ommended.

8.3FID Detector Gases :

8.3.1Hydrogen —99.99mole %minimum.

8.3.2Air —lessthan 10ppm each of total hydrocarbons and water.

9. Hazards

9.1Consult current OSHA regulations, suppliers’Material Safety Data Sheets, and local regulations for all materials used in this test method.

10. Sample Handling

10.1Collect the samples in accordance with Practice D3437.

10.2To preserve sample integrity (consistency)and prevent the loss of volatile components, which may be in some samples, do not uncover samples any longer than necessary. 11. Preparation of Apparatus

11.1Follow the manufacturer’sinstructions for mounting and conditioning the column in the chromatograph.

11.2Adjust the instrument to the conditions as described in Table 1to give the proper separations. Allow sufficient time for the instrument to reach equilibrium as indicated by a stable baseline. See Practices E355and E1510for additional infor-mation on gas chromatography practices and terminology. 12. Procedure

12.1Inject an appropriate amount of specimen, typically 1.0µL,into the chromatograph. A low purity toluene sample chromatogram, which shows the relative retention time of components typically found in commercial toluene, is illus-trated in Fig. 1.

N OTE 1—SinceTCEP is a nonbonded phase, significantretention time shifts can occur with column condition.

an integral quality control tool where toluene is produced or used in manufacturing.

5.2Toluene purity is reported, but a chromatographic analy-sis cannot determine absolute purity if unknown or undetected components are present in the sample.

6. Interferences

6.1If present, nonaromatic hydrocarbons of 13carbons or greater, alcohols, ethers, and other similar organic compounds can interfere with this test method by co-eluting with the aromatic hydrocarbons.

6.2Compounds not detected by a FID are not determined by this test method.

6.3Nonvolatile material is not determined.

7. Apparatus

7.1Gas Chromatograph (GC)—anyGC built for capillary column chromatography. The system shall have sufficient sensitivity, linearity, and range to obtain a minimum peak height response for 0.0010wt %impurity of twice the height of the signal background noise, while not exceeding the full scale of either the detector or the electronic integration for the major component. It shall have a split injection system that will not discriminate over the boiling range of the samples analyzed. The system should be capable of operating at conditions given in Table 1.

TABLE 1Typical Instrumental Parameters

Detector:

Detector temperature, °CColumn:Tubing

Stationary phase Film thickness, µm

Column temperature, °CCarrier Gas

Linear velocity at 70°C,cm/sInlet:

Injection port temperature, °CSplit ratio

Split flow,mL/minSample size, µL

Flame ionization

150°C

50m by 0.25mm Fused silica TCEP 0.4070Helium 25Split 150°C40551.0

7.2Recorder —electronicintegration is recommended. 7.3Capillary Column —fusedsilica capillary column with 1,2,3-tris-2-cyano-ethoxypropane (TCEP)phase is recom-mended. Polyethylene glycol (PEG)columns have been suc-cessfully used. Other columns may be used after it has been established that such a column is capable of separating all major impurities under operating conditions appropriate for the column.

7.4Microsyringe —capableof delivering 1µLof sample. 8. Reagents

8.1Purity of Reagents —Reagentgrade chemicals shall be used in all tests. It is intended that all reagents shall conform to

12.2Measure the area of all peaks. The nonaromatics fraction includes all peaks eluting before benzene. Sum to-gether all nonaromatic peaks and report as a total area.

Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals , BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary , U.S. Pharmacopeial Convention, Inc. (USPC),Rockville, MD.

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TABLE 3Intermediate Precision and Reproducibility

Actual (Weight%)

NonAromatic Std #1Std #2Std #3Benzene Std #1Std #2Std #3Toluene Std #1Std #2Std #3

EthylBenzene Std #1Std #2Std #3

1,4–dioxaneStd #1Std #2Std #3

1.63140.97180.02070.00060.00100.030198.268898.975699.89670.09870.05060.02030.00050.00100.0302

Intermediate Precision 0.00780.00390.00220.00010.00020.00080.00840.00420.00250.00150.00070.00070.00040.00070.0012

Reproducibility

13. Calculation

13.1Using the ECN weight response factors listed in Table 2, calculate the concentration of each component as follows:

C i 51003~A i 3R i ! /

i 51

(~A i 3R i !

n

(1)

0.20240.12430.00810.00020.00030.00700.21420.13270.02720.01850.01160.00510.00080.00080.0079

where:

C i =concentration results for component(s)i , weight %,A i =peak area of component(s)i , and

R i =ECN response factor for component(s)i . 14. Report

14.1Report the following information:

14.1.1Report impurity concentrations less than 0.0005%as

14.1.2Report greater than 0.0005%each of the nonaromat-ics, benzene, ethylbenzene, xylenes, and cumene to the nearest 0.0001%.

14.1.3Report toluene purity to the nearest 0.01%.15. Precision and Bias

15.1Precision —Thefollowing criteria should be used to judge the acceptability of results obtained by this test method (95%confidencelevel). The precision criteria were derived from six laboratories performing three analyses on three standards over a two-day period. The results of the precision study were calculated using Practice E691. 15.1.1Intermediate Precision (formerlycalled Repeatability) —Duplicatedresults obtained on the same sample in the same laboratory by the same operator on the same instrument should not be considered suspect unless they differ by more than the intermediate precision value shown in Table 3.

15.1.2Reproducibility —Duplicatedresults obtained on the same sample by different laboratories, with different operators, different instruments, and at different times should not differ by more than the reproducibility value listed in Table 3.

15.1.3Bias —Systematicdeviation of the method average value or the measured value from an accepted reference value. Since the absolute purity of the toluene solvent could not be determined, an absolute statement of bias could not be deter-mined from this study. An estimate of bias was made by preparing three gravimetric standards with three different concentrations of impurities. The standards were then analyzed as unknowns in the interlaboratory study (seeTable 4).

TABLE 4Estimated Bias

Actual (weight%)

NonAromatic Std #1Std #2Std #3Benzene Std #1Std #2Std #3Toluene Std #1Std #2Std #3

EthylBenzene Std #1Std #2Std #3

1,4–dioxaneStd #1Std #2Std #3

1.63140.97180.02070.00060.00100.030198.268898.975699.89670.09870.05060.02030.00050.00100.0302

Mean

Difference

1.64040.98540.02540.00060.00110.028698.260398.961599.89050.09840.05090.02040.00050.00120.0321

−0.0090−0.0136−0.00470.0000−0.00010.00150.00850.01410.00620.0003−0.0003−0.00010.0000−0.0002−0.0019

TABLE 2Effective Carbon Number Response Factors

Component Nonaromatics:Benzene Toluene

Ethylbenzene p -Xylene m -Xylene o -Xylene Cumene 1,4-Dioxane

Response Factor (Weight)

0.99750.91000.92000.92750.92750.92750.92750.93333.0800

16. Quality Guidelines

16.1Laboratories shall have a quality control system in place.

16.1.1Confirmthe performance of the test instrument or test method by analyzing a quality control sample following the guidelines of standard statistical quality control practices. 16.1.2A quality control sample is a stable material isolated from the production process and representative of the sample being analyzed.

16.1.3When QA/QCprotocols are already established in the testing facility, these protocols are acceptable when they confirmthe validity of test results.

16.1.4When there are no QA/QCprotocols established in the testing facility, use the guidelines described in Guide D6809or similar statistical quality control practices. 17. Keywords

17.1benzene; gas chromatography; impurities; toluene purity;1,4-dioxane

SUMMARY OF CHANGES

Committee D16has identifiedthe location of selected changes to this standard since the last issue (D6526-03´1) that may impact the use of this standard. (ApprovedJune 1, 2010.)

(1) Section 1Scope —added statement on units. (2) Section 16Quality Guidelines added.

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