ASTM D2710-99

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An American National Standard
Designation: D 2710 – 99
Designation: 299/92 (98)
Standard Test Method for
Bromine Index of Petroleum Hydrocarbons by Electrometric
Titration
This standard is issued under the fixed designation D 2710; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 1492 Test Method for Bromine Index of Aromatic Hy-
drocarbons by Coulometric Titration
1.1 This test method covers the determination of the amount
D 5776 Test Method for Bromine Index of Aromatic Hy-
of bromine-reactive material in petroleum hydrocarbons and is
drocarbons by Electrometric Titration
thus a measure of trace amounts of unsaturates in these
materials. It is applicable to materials having bromine indexes
3. Terminology
below 1000.
3.1 Definition:
1.2 This test method is applicable only to essentially olefin-
3.1.1 bromine index—the number of milligrams of bromine
free hydrocarbons or mixtures that are substantially free from
that will react with 100 g of sample under the conditions of the
material lighter than isobutane and have a distillation end point
test.
under 288°C (550°F).
1.3 The values stated in SI units are to be regarded as
4. Summary of Test Method
standard. The values stated in inch-pound units are for infor-
4.1 A known mass of the sample dissolved in a specified
mation only.
solvent is titrated with standard bromide-bromate solution. The
1.4 This standard does not purport to address all of the
end point is indicated by a dead stop electrometric titration
safety concerns, if any, associated with its use. It is the
apparatus when the presence of free bromine causes a sudden
responsibility of the user of this standard to establish appro-
change in the electrical conductivity of the system.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. For specific hazard
5. Significance and Use
statements, see Sections 7 and 8.
5.1 This test method provides a measure of trace amounts of
NOTE 1—This procedure has been cooperatively tested on materials
unsaturated hydrocarbons in petroleum distillates boiling up to
with bromine indexes in the range from 100 to 1000. These materials
288°C (550°F). An estimate of the quantity of these materials
include petroleum distillates such as straight-run and hydrocracked
is useful in assessing the suitability of the lighter fractions for
naphtha, reformer feed, kerosine, and aviation turbine fuel.
use as reaction solvents.
NOTE 2—Materials with bromine index greater than 1000 should be
tested for bromine number using Test Method D 1159/IP 130.
6. Apparatus
NOTE 3—Bromine index of industrial aromatic hydrocarbons should be
determined using Test Method D 1492 or D 5776. 6.1 Electrometric End Point Titration Apparatus—Any ap-
paratus designed to perform titrations to pre-set end points (see
2. Referenced Documents
Note 4) may be used in conjuction with a high-resistance
2.1 ASTM Standards:
polarizing current supply capable of maintaining approxi-
D 1159 Test Method for Bromine Number of Petroleum
mately 0.8 V across two platinum electrodes and with a
Distillates and Commercial Aliphatic Olefins by Electro-
sensitivity such that a voltage change of approximately 50 mV
metric Titration
at these electrodes is sufficient to indicate the end point. Other
types of commercially available electric titrimeters, including
certain pH meters, have also been found to be suitable.
This test method is under the jurisdiction of ASTM Committee D-2 on
NOTE 4—Pre-set end point indicated with polarized electrodes provides
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
a detection technique similar to the dead stop technique specified in
D02.04.OD on Physical Methods.
Current edition approved June 10, 1999. Published August 1999. Originally previous versions of this test method.
published as D 2710 – 68. Last previous edition D 2710 – 94.
In the IP, this test method is under the jurisdiction of the Standardization
Committee.
2 3
Annual Book of ASTM Standards, Vol 05.01. Annual Book of ASTM Standards, Vol 06.04.
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D 2710
6.2 Titration Vessel—A jacketed glass vessel of approxi-
A = millilitres of the Na S O solution required fortitra-
2 2 2 3
mately 150-mL capacity of such a form that can be conve-
tion of the bromide-bromate solution.
niently maintained at 0 to 5°C (32 to 41°F). A pair of platinum
NOTE 5—Warning: Poison. Combustible. May be fatal if swallowed.
electrodes spaced not more than 5 mm apart shall be mounted
Causes severe burns. Harmful if inhaled.
to extend well below the liquid level. Stirring shall be by a
NOTE 6—Warning: Poison. Corrosive. May be fatal if swallowed.
mechanical or electromagnetic stirrer and shall be rapid, but
Liquid and vapor cause severe burns. Harmful if inhaled.
not so vigorous as to draw air bubbles down to the electrodes.
7.3.2 Potassium Iodide Solution (150 g/L)—Dissolve 150 g
6.3 Burets, 10 and 50-mL capacity.
of KI in water and dilute to 1 L.
6.4 Iodine Number Flasks, glass-stoppered, 500-mL capac-
7.3.3 Sodium Thiosulfate, Standard Solution (0.05 N)—
ity.
Dissolve 12.5 g of sodium thiosulfate pentahydrate (Na S O ·
2 2 3
5H O) in water and add 0.01 g of sodium carbonate (Na CO )
7. Reagents
2 2 3
to stabilize the solution. Dilute to 1 L and mix thoroughly by
7.1 Purity of Reagents—Reagent grade chemicals shall be
shaking. Standardize by any accepted procedure that deter-
used in all tests. Unless otherwise indicated, it is intended that
mines the normality with an error not greater than 60.0002.
all reagents shall conform to the specifications of the American
Restandardize at intervals frequent enough to detect changes of
Chemical Society where such specifications are available.
0.0005 in normality.
Other grades may be used, providing it is first ascertained that
7.3.4 Starch Indicator Solution—Mix5gof soluble starch
the reagent is of sufficiently high purity to permit its use
with approximately 3 to 5 mL of water. If desired, add about
without lessening the accuracy of the determination.
0.65 g salicylic acid as preservative. Add the slurry to 500 mL
7.2 Purity of Water—Unless otherwise indicated, references
of boiling water and continue boiling for 5 to 10 min. Allow to
to water shall be understood to mean distilled water, or water
cool and decant the supernatant liquid into glass bottles and
of equivalent purity.
seal well. Starch solutions (some preserved with salicylic acid)
7.3 Preparation and Standardization:
are also commercially available and may be substituted.
7.3.1 Bromide-Bromate Standard Solution (0.05 N)—
7.3.5 Sulfuric Acid (1+5)—Carefully add 1 volume of
Dissolve 5.1 g of potassium bromide (KBr) and 1.4 g potas-
concentrated sulfuric acid (H SO , sp gr 1.84) to 5 volumes of
2 4
sium bromate (KBrO ) in water and dilute to 1 L. Standardize
water and thoroughly mix. (Warning—See Note 7.)
to four significant figures as follows: Place 50 mL of glacial
acetic acid (Warning—See Note 5.) and 1 mL of concentrated
NOTE 7—Warning: Poison. Corrosive. Strong Oxidizer. Contact with
organic material may cause fire. May be fatal if swallowed.
hydrochloric acid (HCl, sp gr 1.19) (Warning—See Note 6.) in
a 500-mL iodine number flask. Chill the solution in an ice bath
7.3.6 Titration Solvent—Prepare 1 L of titration solvent by
for approximately 10 min, and with constant swirling of the
mixing the following volumes of materials: 714 mL of glacial
flask, add from a 50-mL buret 40 to 45 mL of bromide-bromate
acetic acid, 134 mL of 1,1,1-trichloroethane or dichlo-
solution, estimated to the nearest 0.01 mL, at a rate such that
romethane, 134 mL of methanol, and 18 mL of H SO (1+5)
2 4
the addition takes between 90 and 120 s. Stopper the flask
(see 7.3.5).
immediately, shake the contents, place it again in the ice bath,
7.4 Solvents:
and add 5 mL of potassium iodide (KI) solution in the lip of the
7.4.1 Acetic Acid, glacial. (Warning—See Note
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