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: D1492 − 21
Standard Test Method for
Bromine Index of Aromatic Hydrocarbons by Coulometric
Titration1
This standard is issued under the fixed designation D1492; 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
1.1 This test method covers the determination of Bromine 2.1 ASTM Standards:2
Index in aromatic hydrocarbons, their derivatives, and related D891 Test Methods for Specific Gravity, Apparent, of Liquid
chemicals. Industrial Chemicals
D1193 Specification for Reagent Water
1.2 This test method is applicable to samples with Bromine D3437 Practice for Sampling and Handling Liquid Cyclic
Index concentrations to 100 Bromine Index. The limit of Products
detection (LOD) is for 1.5 Bromine Index and the limit of D3505 Test Method for Density or Relative Density of Pure
quantitation (LOQ) is 4.9 Bromine Index. Liquid Chemicals
NOTE 1—LOD and LOQ were calculated using data from the D16 PTP
D4052 Test Method for Density, Relative Density, and API
program. This estimate of LOD includes within-lab variability. Gravity of Liquids by Digital Density Meter
D5776 Test Method for Bromine Index of Aromatic Hydro-
1.3 The following applies for the purposes of determining carbons by Electrometric Titration
the conformance of the test results using this test method to D6809 Guide for Quality Control and Quality Assurance
applicable specifications, results shall be rounded off in accor- Procedures for Aromatic Hydrocarbons and Related Ma-
dance with the rounding-off method of Practice E29. terials
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1.4 The values stated in SI units are to be regarded as E29 Practice for Using Significant Digits in Test Data to
standard. No other units of measurement are included in this Determine Conformance with Specifications
standard. E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
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- 1910.12003
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 Definitions:
1.6 This international standard was developed in accor- 3.1.1 bromine index (B), n—the number of milligrams (mg)
dance with internationally recognized principles on standard- of bromine consumed by 100 g of sample under given
ization established in the Decision on Principles for the conditions (mg-Br/100 g).
Development of International Standards, Guides and Recom- 4. Summary of Test Method
mendations issued by the World Trade Organization Technical
4.1 The specimen is added to a solvent and titrated with
Barriers to Trade (TBT) Committee.
electrolytically generated bromine at room temperature. The
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
1
This test method is under the jurisdiction of ASTM Committee D16 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsi- Standards volume information, refer to the standard’s Document Summary page on
bility of Subcommittee D16.04 on Instrumental Analysis. the ASTM website.
3
Current edition approved Nov. 1, 2021. Published January 2022. Originally Available from U.S. Government Printing Office Superintendent of Documents,
approved in 1957. Last previous edition approved in 2013 as D1492 – 13. DOI: 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
10.1520/D1492-21. www.access.gpo.gov.
*A Summary of Changes section appears at the end of this standard
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D1492 − 21
FIG. 1 Automatic Amperometric-Coulometric Titrator Circuit
end point is determined by a dead-stop method. The time of where such specifications are available.4 Other grades may be
titration is proportional to the bromine added to the specimen. used, provided it is first ascertained that the reagent is of
sufficiently high purity to permit its use without lessening the
5. Significance and Use accuracy of the determination.
5.1 This test method is useful as an internal quality control 7.2 Purity of Water—Unless otherwise indicated, references
tool, and for use in development or research work on industrial to water shall be understood to mean reagent water conforming
aromatic hydrocarbons and related materials. This test method to Type I or Type II of Specification D1193.
gives a broad indication of olefinic content. It will not 7.3 Electrolyte:
differentiate between the types of aliphatic unsaturation. 7.3.1 Preparation Cell Electrolyte—To make 1 L, mix
600 mL of glacial acetic acid, 260 mL of absolute methanol,
6. Apparatus and 140 mL of KBr solution (119g/L).
6.1 Amperometric-Coulometric Apparatus, automatic, suit- 7.4 Potassium Bromide Solution (119 g/L)—Dissolve 119 g
able for bromine index titrations with variable generator of potassium bromide (KBr) in water and dilute to 1 L.
current and timer. A typical circuit diagram of suitable equip-
ment is shown in Fig. 1. 8. Hazards
6.2 Syringe, 2 mL with needle and rubber cap seal. 8.1 Consult current OSHA regulations, supplier’s Safety
Data Sheets, and local regulations for all materials used in this
6.3 Stirrer, magnetic. test method.
7. Reagents 4
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
7.1 Purity of Reagent—Reagent grade chemicals shall be Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by the American Chemical
used in all tests. Unless otherwise indicated, it is intended that
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
all reagents shall conform to the specifications of the Commit- U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
tee on Analytical Reagents of the American Chemical Society, copeial Convention, Inc. (USPC), Rockville, MD.
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D1492 − 21
9. Sampling 11. Calculation
9.1 Sample the material in accordance with Practice D3437. 11.1 Calculate the bromine index, B (mg-Br/100 g), as
follows:
10. Procedure T 3 I 3 79.9
10.1 Place 125 mL of electrolyte in a clean, dry titration B5 (1)
965W
cell, insert the electrodes, and begin stirring. Verify the volume
of electrolyte is sufficient to ensure the electrodes are com- where:
pletely submerged and if necessary, increase the volume of T = titration time, s,
electrolyte required. Apply the generation current in accor- I = generation current, mA,
dance with Table 1. W = weight of specimen, g,
79.9 = MW bromine (grams/mole), and
965 = Faraday’s constant (96 500 coulomb/mole)/100.
TABLE 1 Specimen Size and Generation Current 12. Report
Estimated Specimen Weight, Generation
Bromine Index g Current, mA
12.1 Report the following information:
0 to 20 1.000 1.0
12.1.1 Report bromine index to the nearest 0.1 unit.
20 to 100 0.600 5.0
13. Precision and Bias5
13.1 An ILS was conducted which included five laborato-
ries analyzing two samples. Practice E691 was followed for the
10.2 Before introducing the specimen and immediately design and analysis of the data; the details are given is ASTM
before each determination, bring the coulometer to equilib- Research Report D16-2004. The ILS did not meet the mini-
rium. mum requirements of Practice E691 for six labs, four materials,
10.3 Draw into the syringe the amount of sample prescribed and two replicates.
in Table 1 corresponding to the estimated bromine index. Wipe 13.2 Repeatability:
the needle with a clean cloth, attach a rubber cap seal to the 13.2.1 Results should not be suspect unless they differ by
needle, and weigh on the analytical balance. Remove the seal, more than shown in Table 2. On the basis of test error alone,
add the specimen to the electrolyte, and set the timer to zero. the difference between two results obtained in the same
Replace the seal, reweigh the syringe, and calculate the laboratory on the same material will be expected to exceed this
specimen weight. value only 5 % of the time.
NOTE 2—If the density or specific gravity of the specimen is known 13.3 Reproducibility:
(Test Methods D891, D3505, or D4052 can be used), the specimen can be 13.3.1 Results submitted by two labs should not be consid-
added by means of a pipet or microburet and the weight calculated. ered suspect unless they differ by more than shown in Table 2.
10.4 Begin titration of the specimen. As the titration On the basis of test error alone, the difference between two
proceeds, keep the generation current at the selected value. The results obtained in different laboratories on the same material
generation of bromine will continue as long as it is consumed will be expected to exceed this value only 5 % of the time.
by the sample. At the end point an incremental increase in 13.4 Proficiency Testing Information:
bromine concentration causes the titration and timer to stop 13.4.1 The following information is included as general
automatically. Forty seconds after the titration has shut off, information. Proficiency testing is done by sending a single
continue the titration. If the titration cuts off, immediately, the sample to multiple laboratories that routinely analyze the
end point has been reached and the titration may be considered
complete. Otherwise, it may be necessary to continue the
titration in steps, waiting about 40 s between steps, until the 5
Supporting data have been filed at ASTM International Headquarters and may
titration time increment is 4 s or less. Note the total titration be obtained by requesting Research Report RR:D16-2004. Contact ASTM Customer
time and generation current. Service at service@astm.org.
TABLE 2 Summary of D1492 Precision
Sample Name Replicates (n) Conc. mg Repeatability Reproducibility LOD
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Br/100 g r R
p-xylene 29 16 35
Xylene-Plant Feed 43 7 25
A
D16 PTP program 30 1.4 3.8
D16 PTP program 21B 74 19
D16 PTP program 28C 93 34
A
2018 – 2020.
B
2014 – 2015.
C
2016 – 2017.
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D1492 − 21
material. The sample is analyzed one time. These results were 14.2 Interlaboratory Testing:
obtained from ASTM’s D16 Proficiency Testing Program. 14.2.1 A program that includes multiple laboratories ana-
lyzing the same samples is strongly encouraged. This program
14. Quality Guidelines Mandatory for D16 Standards
should allow labs to compare their results with other labora-
14.1 Laboratories shall have a quality control system in tories. This is particularly important when a plant is selling the
place. product to customers or the laboratory is analyzing the product
14.1.1 Confirm the performance of the test instrument or for acceptance. Producers and customers need to have confi-
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test method by analyzing a quality control sample following dence that results from different producers are comparable.
the guidelines of standard statistical quality control practices.
ASTM currently has a Proficiency Testing Program that sends
14.1.2 A quality control sample is a stable material isolated
a sample of mixed xylenes, p-xylene, and benzene to multiple
from the production process and representative of the sample
labs twice a year for testing. Other programs are acceptable.
being analyzed.
14.1.3 When QA/QC protocols are already established in
the testing facility, these protocols are acceptable when they 15. Keywords
confirm the validity of test results. 15.1 aromatic hydrocarbons; bromine index; bromine-
14.1.4 When there are no QA/QC protocols established in reactive; coulometric titration; titration
the testing facility, use the guidelines described in Guide
D6809 or similar statistical quality control practices.
SUMMARY OF CHANGES
Committee D16 has identified the location of selected changes to this standard since the last issue
(D1492 – 13) that may impact the use of this standard. (Approved November 1, 2021.)
(1) Replaced Scope to conform with D16 Editorial Guidelines. (3) Revised precision using PTP data.
(2) Changed type water from type IV to type I or II. (4) Revised Quality Section 14.
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