ASTM D1123-99(2003)e1
(Test Method)Standard Test Methods for Water in Engine Coolant Concentrate by the Karl Fischer Reagent Method
Standard Test Methods for Water in Engine Coolant Concentrate by the Karl Fischer Reagent Method
SIGNIFICANCE AND USE
The total apparent water in engine coolant concentrate as determined by Karl Fischer titrations consists of the fol-
lowing: (1) water present in the original glycol base; (2) water added (for example, inhibitor solutions); (3) water of hydration of inhibitors (for example, Na 2B4O7·5H2O); ( 4) water formed in the chemical reaction between borate and ethylene glycol, producing boratediol condensate and water; and ( 5) quantitative interference by the reaction of the reagent with inhibitors such as tetraborate or sodium hydroxide.
SCOPE
1.1 These test methods cover the determination of the water present in new or unused glycol-based coolant concentrates using a manual (Test Method A) or an automatic (Test Method B) coulometric titrator procedure.
1.2 Many carbonyl compounds react slowly with the Fischer reagent, causing a fading end point and leading to high results. A modified Fischer reagent procedure is included that minimizes these undesirable and interfering reactions.
1.3 This standard does not purport to address all of the safety problems, 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 hazards statements see Sections 8 and 16.
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Designation:D1123–99 (Reapproved 2003)
Standard Test Methods for
Water in Engine Coolant Concentrate by the Karl Fischer
Reagent Method
This standard is issued under the fixed designation D1123; 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.
This standard has been approved for use by agencies of the Department of Defense.
´ NOTE—Definitions, 3.1, was changed to Descriptions of Terms editorially in April 2007.
1. Scope 3.1.1.1 Discussion—View the color by transmitted daylight
or by transmitted light from an artificial daylight lamp, such as
1.1 These test methods cover the determination of the water
one that complies with the specification given in Test Method
present in new or unused glycol-based coolant concentrates
D156.
using a manual (Test MethodA) or an automatic (Test Method
3.1.2 instrument end point—for the purpose of these tests,
B) coulometric titrator procedure.
that point in the titration when two small platinum electrodes,
1.2 Many carbonyl compounds react slowly with the Fis-
upon which a potential of 20 to 50 mVhas been impressed, are
cher reagent, causing a fading end point and leading to high
depolarized by the addition of 0.05 mL of Fischer reagent (6
results. A modified Fischer reagent procedure is included that
mg of water/mL), causing a change of current flow of 10 to 20
minimizes these undesirable and interfering reactions.
µA that persists for at least 30 s.
1.3 This standard does not purport to address all of the
3.1.2.1 Discussion—This end point is sometimes incor-
safety problems, if any, associated with its use. It is the
rectly called the “dead stop,” which is the reverse of the above.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
4. Summary of Test Methods
bilityofregulatorylimitationspriortouse.Forspecifichazards
4.1 These test methods are based essentially on the reduc-
statements see Sections 8 and 16.
tion of iodine by sulfur dioxide in the presence of water. This
2. Referenced Documents reaction can be used quantitatively only when pyridine and an
2 alcohol are present to react as follows:
2.1 ASTM Standards:
D156 Test Method for Saybolt Color of Petroleum Products I 1 SO 1 H O→ SO 1 2HI (1)
2 2 2 3
(Saybolt Chromometer Method)
D1176 Practice for Sampling and Preparing Aqueous Solu-
4.2 In order to determine water, Karl Fischer reagent is
tions of Engine Coolants orAntirusts for Testing Purposes
added to a solution of the sample in anhydrous high-purity
D1193 Specification for Reagent Water
methanol until all water present has been consumed. This is
E203 Test Method for Water Using Volumetric Karl Fischer
evidenced by the persistence of the orange-red end point color,
Titration
or alternatively by an indication on a galvanometer or similar
current-indicating device that records the depolarization of a
3. Terminology
pair of noble metal electrodes. The reagent is standardized by
3.1 Definitions of Terms Specific to This Standard:
the titration of water.
3.1.1 color end point—that point during the titration when
NOTE 1—It is believed that these methods give all the information
the color change from yellow to orange-red is sharp and easily
required for determining the water in coolant formulations. Should
repeated. The orange-red color must persist for at least 30 s in
additional information on water determinations be needed, reference
order to indicate an end point.
should be made to Test Method E203.
5. Significance and Use
5.1 The total apparent water in engine coolant concentrate
These test methods are under the jurisdiction of ASTM Committee D15 on
Engine Coolants and are the direct responsibility of Subcommittee D15.04 on
as determined by Karl Fischer titrations consists of the fol-
Chemical Properties.
lowing: (1) water present in the original glycol base; (2) water
Current edition approved . Published August 1999. Originally published as
added (for example, inhibitor solutions); (3) water of hydration
D1123 – 50. Last previous edition D1123 – 93. DOI: 10.1520/D1123-99R03E01.
Annual Book of ASTM Standards, Vol 05.01. of inhibitors (for example, Na B O ·5H O); ( 4) water formed
2 4 7 2
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D1123–99 (2003)
in the chemical reaction between borate and ethylene glycol, 6.4 Buret Assembly for Fischer reagent, consisting of a 25
producing boratediol condensate and water; and ( 5) quantita- or 50-mL buret connected by means of glass (not rubber)
tive interference by the reaction of the reagent with inhibitors connectors to a source of reagent; several types of automatic
such as tetraborate or sodium hydroxide. dispensing burets may be used. Since the reagent loses
strength when exposed to moist air, all vents must be protected
TEST METHOD A—MANUAL TITRATION
against atmospheric moisture by adequate drying tubes con-
taining anhydrous calcium sulfate. All stopcocks and joints
6. Apparatus
should be lubricated with a lubricant not particularly reactive
6.1 Titration Vessel— For color end point titrations, use a
with the reagent.
100 or 250-mL volumetric flask, which need not be calibrated.
6.5 Weighing Bottle, of the Lunge or Grethen type, or
For instrument end point, a 250-mL flask fitted with inter-
equivalent.
changeable electrodes (Fig. 1) may be used. This is particu-
6.6 Some laboratory equipment suppliers offer a Karl Fis-
larly good for titrations of coolant concentrate that is deeply
cher apparatus. The noted model or its equivalent has been
coloredfromdyeoranyothercause.Forpermanentlymounted 8
found to be suitable.
assemblies, the vessel should have a capacity about equal to
that of a 300-mLtall-form beaker and should be provided with
7. Reagents
a tight-fitting closure to protect the sample and reagent from
7.1 Purity of Reagents—Reagent grade chemicals shall be
atmospheric moisture, a stirrer, and a means of adding sample
used in all tests. Unless otherwise indicated, it is intended that
and reagents and removing spent reaction mixture. It is
all reagents shall conform to the specifications of the Commit-
desirable to have a means for cooling the titration vessel to ice
tee onAnalytical Reagents of theAmerican Chemical Society,
temperature.
where such specifications are available. Other grades may be
6.2 Instrument Electrodes, platinum with a surface equiva-
used, provided it is first ascertained that the reagent is of
lent to two No. 26 wires, 4.76-mm long. The wires should be
sufficiently high purity to permit its use without lessening the
3 to 8 mm apart and so inserted in the vessel that the liquid will
accuracy of the determination.
cover them.
7.2 Unless otherwise indicated, references to water shall be
6.3 Instrument Depolarization Indicator, having an internal
understood to mean reagent water, Type IV, conforming to
resistance of less than 5000 V and consisting of a means of
Specification D1193.
impressing and showing a voltage of 20 to 50 mV across the
7.3 Karl Fischer Reagent, equivalent to 5 mg of water/
electrodes and capable of indicating a current flow of 10 to 20
mL.
µA by means of a galvanometer or radio tuning eye circuit.
7.4 Methanol (Warning—See 8.1.)—Anhydrous, high pu-
rity.
Flasks made by Rankin Glass Blowing Co., 3920 Franklin Canyon Rd.,
8. Hazards
Martinez, CA have been found satisfactory for this purpose.
A type similar to the Precision Scientific Co. “Aquatrator” or Fisher Scientific
8.1 Methanol—Poison; flammable; may be fatal or cause
Co. “FisherTitrimeter,” is suitable for the measurement of the instrument end point.
blindness if swallowed; cannot be made non-poisonous; harm-
ful if inhaled.
9. Sampling
9.1 A representative sample of the contents of the original
container shall be obtained as directed in Test Method D1176;
even if two phases are present, the water-insoluble phase
should not be separated.
A type similar to Catalog No. J-821 of Scientific Glass Apparatus Co.,
Bloomfield, NJ, or Catalog No. 750 of Eck and Krebs, New York, NY, has been
specifically designed for this purpose and presents the minimum contact of reagent
with stopcock lubricant.
Indicating Drierite has been found satisfactory for this purpose.
Suitable lubricants includeApiezon N. (James G. Biddle and Co., Philadelphia,
PA); High Vacuum Silicone Grease (Dow Corning Co., Midland, MI); Sisco 300
(Swedish Iron and Steel Co., New York, NY).
Metrohm Herisau, Karl Fischer Titrator Type E-452 available from Brinkmann
Instruments, Inc., Cantaigue Road, Westbury, NY 11590.
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.
NOTE 1—All dimensions in millimetres.
Reagents, as the pyridine-free hydranal reagent, available from Fisher Scien-
FIG. 1 Titration Flask Assembly tific, Pittsburgh, PA 15219.
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D1123–99 (2003)
fromundertheburettip,wipethetipwithacleandryclothinadownward
10. Standardization of Reagent
motion.
10.1 Standardize the Fischer reagent at least once, prior to
use, each day the procedure is used, by either the color or
12. Calculation
instrument end point (see Section 3) method, using the proce-
12.1 Calculate the total water content (free plus apparent) of
dure as used for titrating the sample (Section 11).
the sample as follows:
10.1.1 Add to each 250 mL flask 25 mL of anhydrous, high
Water, weight % 5 VF/10M (3)
purity methanol. Stir rapidly. Titrate with Karl Fischer reagent
according to 11.2. Add to the solution 0.15 to 0.18 g of water
(to 60.1 mg) by use of an accurately sized syringe. Titrate
where:
again and record the volume of titrant used. Repeat standard-
V = mL of Karl Fischer reagent required by the sample,
ization two more times.
F = equivalency factor for Karl Fischer reagent, mg of
10.1.2 Calculate the equivalency factor of the reagent in
water per mL of reagent, and
terms of water content per millilitre as follows: M = sample used, g.
Equivalency factor, F , mg of water/mL 5 A/B (2)
13. Precision and Bias
13.1 Precision—The following data should be used for
where:
judging the acceptability of results (95 % probability):
A = mg of water used in the standardization, and
13.1.1 Repeatability—Duplicate results by the same opera-
B = Karl Fischer reagent required, mL.
tor should be considered suspect if they differ by more than the
following amount:
11. Procedure
Repeatability 0.5 mL of titrant
11.1 Introduce 30 to 50 mL of the anhydrous high-purity
13.1.2 Reproducibility—The result submitted by one labo-
methanol into a 250 mL Erlenmeyer flask, making sure, if an
ratory should not be considered suspect unless it differs from
instrument end point apparatus is used, that the electrodes are
that of another laboratory by more than the following amount:
covered by this amount of methanol. If the color end point is to
Water Content, % Reproducibility, % of mean
be determined, make up a second flask as well.
11.2 Adjust the stirrer, if any, to provide adequate mixing
0.1to1.0 15
1.0to10 5
without splashing. Titrate the mixture to the instrument end
point (3.1.2), or the color end point (3.1.1), with Karl Fischer
13.2 Bias—Since there is no accepted reference material
reagent.Ifthecolorendpointistobeobserved,titrateoneflask
suitable for determining the bias for the procedure in this test
to match the first. Set aside the first flask as a comparison
method, bias has not been determined.
standard for titrating the sample.
11.3 To the titration mixture thus prepared, add an amount TEST METHOD B—COULOMETRIC TITRATION
of sample as indicated in Table 1. Exercise care when the
14. Apparatus
sample is transferred so that water is not absorbed from the air,
,
11 12
particularly under conditions of high humidity. Again, titrate
14.1 Coulometric Titrator —A complete control unit
themixturewithKarlFischerreagenttothesameinstrumentor with titration chamber and clamp, platinum sensing electrodes,
color end point previously employed. Record the amount of
generator, magnetic stirrer, and meeting requirements 14.2 and
reagent used to titrate the water in the sample. 18.1.
14.2 The instrument used for determining water in liquids is
NOTE 2—When using the volumetric flask-type titration vessel in
designed and calibrated to deliver a known number of milli-
humid climate, place a piece of thin paraffin wax over the mouth of the
amperes of current which generates sufficient iodine to neu-
vessel. Provide a small hole for introducing the buret tip. In less humid
climates it is sufficient to lower the tip of the buret deeply into the long tralize a known number of micrograms of water per minute.
neck of the titration flask.
14.3 In order to determine the water content of engine
NOTE 3—In titrating with the volumetric flask-type titration vessel,
coolants, this method requires a two-part titration solution that
avoidwettingthestopperandupperendoftheflaskwitheitherthereagent
is brought to zero dryness by iodine produced by the generator
orthesamplesolvent.Eachtimethetitrationisinterrupted,touchtheburet
when the instrument is powered up. The sample is added and
tip to the neck of the flask to remove droplets which, if not removed,
the water content is read directly in micrograms.
would absorb moisture from the atmosphere. When the flask is removed
14.4 Glass Syringe, 50-mL, for removing excess solution
from the titration chamber.
14.5 Syringe, 25-µL, fitted with a 11.5-cm hypodermic
TABLE 1 Recommended Sample Sizes
needle for introduction of samples into the titration chamber.
Sample
Water Content,
Size, Sample Method
weight %
g
This procedure is patented by the Photovolt Corp. under U. S. Patent
2.5 to 10 0.3 Introduce samples by using weigh bottles or
3,726,778 and has been included in the standard under Paragraph 11.2 of the
disposable, accurate syringes. Obtain sample
Regulations Governing ASTM Technical Committees. Procedure A is a non-
weight by difference.
patented alternative method.
0.5to2.5 3
Below 0.5 20 A detailed drawing is available from ASTM Headquarters. Request Adjunct
No. 12-415330-00.
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D1123–99 (2003)
14.6 Syringe,1-µL,fittedwitha11.5-cmhypodermi
...
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