ASTM D890-98(2003)
(Test Method)Standard Test Method for Water in Liquid Naval Stores
Standard Test Method for Water in Liquid Naval Stores
SIGNIFICANCE AND USE
Many naval stores products contain water as a result of the processes used for their production. Typically refined products such as terpenes, pine oil, tall oil fatty acids, and distilled tall oil contain only traces of water, but crude tall oil might contain 0.5 to 2.5 % of water. Although the Karl Fischer and coulometric methods are most applicable to low levels of moisture, these can be and are used at higher levels. The azeotropic distillation method is generally used at higher levels.
SCOPE
1.1 These test methods cover the quantitative determination of dissolved or occluded water present in any proportion in liquid naval stores, such as turpentine, pinene, dipentene, pine oil, tall oil, and tall oil fatty acids. Three methods of moisture testing are included. The Karl Fisher titration method is the preferred method for testing tall oil, Test Methods D 803.
1.1.1 The Karl Fischer Titration method is based on the reaction between water and a complex reagent consisting of iodine, sulfur dioxide, pyridine, and methanol, whereby the iodine is converted to a colorless compound. The appearance of a persistent iodine color in the reaction mixture indicates the complete removal of free water by reaction with the reagent, and the endpoint may be measured colorimetrically. Automatic titrators find this endpoint by the restoration of a current strength when the resistance provided by the presence of water is eliminated. Amperometric automatic titrators find this endpoint by detecting the current flow that occurs once water is eliminated.
1.1.2 The coulometric titration method determines water content by electronic integration of a current sufficient to generate the precise amount of iodine from the required reagent to react with the water in the sample.
1.1.3 The azeotropic method utilizes the relatively low boiling point of water, as compared with other sample constituents, in a toluene or xylene matrix so that water is collected in a trap and measured.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 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.
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Designation:D890–98(Reapproved2003)
Standard Test Method for
Water in Liquid Naval Stores
This standard is issued under the fixed designation D 890; 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 responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 These test methods cover the quantitative determination
bility of regulatory limitations prior to use.
of dissolved or occluded water present in any proportion in
liquid naval stores, such as turpentine, pinene, dipentene, pine
2. Referenced Documents
oil, tall oil, and tall oil fatty acids. Three methods of moisture
2.1 ASTM Standards:
testing are included. The Karl Fisher titration method is the
D 803 Test Methods for Tall Oil
preferred method for testing tall oil, Test Methods D 803.
D 1364 Test Method for Water in Volatile Solvents (Fischer
1.1.1 The Karl Fischer Titration method is based on the
2 Reagent Titration Method)
reaction between water and a complex reagent consisting of
iodine, sulfur dioxide, pyridine, and methanol, whereby the
3. Significance and Use
iodine is converted to a colorless compound. The appearance
3.1 Many naval stores products contain water as a result of
of a persistent iodine color in the reaction mixture indicates the
the processes used for their production. Typically refined
complete removal of free water by reaction with the reagent,
products such as terpenes, pine oil, tall oil fatty acids, and
and the endpoint may be measured colorimetrically.Automatic
distilled tall oil contain only traces of water, but crude tall oil
titrators find this endpoint by the restoration of a current
might contain 0.5 to 2.5 % of water.Although the Karl Fischer
strength when the resistance provided by the presence of water
and coulometric methods are most applicable to low levels of
is eliminated. Amperometric automatic titrators find this end-
moisture, these can be and are used at higher levels. The
point by detecting the current flow that occurs once water is
azeotropic distillation method is generally used at higher
eliminated.
levels.
1.1.2 The coulometric titration method determines water
content by electronic integration of a current sufficient to
Moisture By Karl Fischer Titration
generatethepreciseamountofiodinefromtherequiredreagent
(Preferred method)
to react with the water in the sample.
1.1.3 The azeotropic method utilizes the relatively low 4. Apparatus
boiling point of water, as compared with other sample con-
4.1 Titration Vessel, preferably closed, with stirring capa-
stituents,inatolueneorxylenematrixsothatwateriscollected
bilities,
in a trap and measured.
4.2 Buret, capable of being read at 0.1 mL divisions, or
1.2 The values stated in SI units are to be regarded as the
automatic buret, or
standard. The values given in parentheses are for information
4.3 Automatic Karl Fischer titrator.
only.
4.4 Balance, capable of weighing to the nearest 0.0001 g.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 5. Reagents
5.1 Karl Fischer Reagent, or Other Suitable Reagent, such
as Pyridine-free Adaptations of Karl Fischer Reagent. Re-
This test method is under the jurisdiction of ASTM Committee D01 on Paint agents vary in strength (titer). This test method is written
and Related Coatings, Materials, andApplications and is the direct responsibility of
assuming a titer of 5 mg water/mL reagent. Recommended
Subcommittee D01.34 on Naval Stores.
additions of water in this test method may need to be adjusted
Current edition approved Dec. 1, 2003. Published December 2003. Originally
depending on the titer of the reagent.
approved in 1946. Last previous edition approved in 1998 as D 890 - 98.
This procedure has been adapted from the method of Karl Fischer published in
5.2 Methanol—ACS grade.
Zeitschrift für Angewandte Chemie, Vol 48, 1935, p. 395; Chemical Abstracts,Vol
29, 1935, p. 6532; as modified by Smith, Bryant, and Mitchell, Journal, Am.
Chemical Soc., Vol. 61, 1939, p. 2407; and further modified by Axel Johansson,
SvenskPapperstidning,Vol50,No.11B,1947,p.124;seealsoPublication19ofthe For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Swedish Wood Research Institute, Wood Chemistry and Paper Technique (Stock- contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
holm) (1947). Karl Fischer reagent is available from various laboratory supplies. Standards volume information, refer to the standard’s Document Summary page on
Pyridine-free adaptations of the Karl Fischer reagent are available commercially. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D890–98 (2003)
6. Standardization of Iodine Reagent Moisture By Coulometric Titration
6.1 Add methanol to the titration vessel, and titrate with
10. Apparatus
reagent until the lemon-yellow color just changes to a red-
10.1 Coulometric Karl Fischer Titrator.
brown color, or, if an automatic titrator is used, until the
10.2 Sample Vials, 8-mL or 4-dram
readings indicate no free water present. The titration vessel is
10.3 Medicine Dropper.
now ready for titrating, and is considered conditioned.
10.4 Disposable Plastic Syringes, 1-cc with 16, 18 or 20
6.2 Add a drop of water, weighed to the nearest 0.0001 g, to
gage needles.
the titration vessel by use of a transfer pipet, or a weighing
10.5 Syringe,10µL
pipet, weighing the pipet before and after the addition. Each
drop will weigh approximately 0.03 g and will require roughly
11. Reagents
6 mL of titrant having a titer of 5 mg/mL. Alternatively, a
11.1 See 5.1.
25-µL, or other volume syringe may be used to introduce exact
volumes.
12. Instrument Preparation
6.3 Titrate with reagent until the lemon-yellow color just
12.1 Prepare and calibrate the instrument according to the
changes to a red-brown color, or, if an automatic titrator is
manufacturer’s operating instructions. This generally includes:
used, until the readings indicate no free water present. Record
12.1.1 Clean and assemble the titration chamber.
the mL of titrant used.
12.1.2 Pour titration solution into the chamber.
6.4 Calculate the water equivalent of the iodine reagent, in
12.1.3 Add the iodine generator solution to the generator
milligrams of water
...
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