ASTM D4377-00

Standard Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration

SCOPE
1.1 This test method covers the determination of water in the range from 0.02 to 2% in crude oils. Mercaptan and sulfide (S- or H2S) sulfur are known to interfere with this test method (see Section 5).  
1.2 This test method is intended for use with standard Karl Fischer reagent or pyridine-free Karl Fischer reagents.
1.3 The values stated in SI units are to be regarded as the standard.  
1.4 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. Specific precautionary statements are given in Section 7.

General Information

• Status: Historical
• Publication Date: 09-Aug-2000
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.02 - Hydrocarbon Measurement for Custody Transfer (Joint ASTM-API)

Relations

• Replaced By: ASTM D4377-00e1 - Standard Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration
• Effective Date: 10-Aug-2000
• Referred By: ASTM D7829-13(2018) - Standard Guide for Sediment and Water Determination in Crude Oil
• Effective Date: 10-Aug-2000
• Referred By: ASTM D7785-21 - Standard Practice for Water in Lint Cotton by Oven Evaporation Combined with Volumetric Karl Fischer Titration
• Effective Date: 10-Aug-2000
• Referred By: ASTM D6470-99(2020) - Standard Test Method for Salt in Crude Oils (Potentiometric Method)
• Effective Date: 10-Aug-2000
• Referred By: ASTM G205-16 - Standard Guide for Determining Emulsion Properties, Wetting Behavior, and Corrosion-Inhibitory Properties of Crude Oils
• Effective Date: 10-Aug-2000
• Referred By: ASTM D4052-22 - Standard Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
• Effective Date: 10-Aug-2000
• Referred By: ASTM D5002-22 - Standard Test Method for Density, Relative Density, and API Gravity of Crude Oils by Digital Density Analyzer
• Effective Date: 10-Aug-2000
• Referred By: ASTM D6448-16(2022) - Standard Specification for Industrial Burner Fuels from Used Lubricating Oils
• Effective Date: 10-Aug-2000
• Referred By: ASTM F3337-19 - Standard Guide for Taking Property and Behavior Measurements on Weathered Fractions of Oil
• Effective Date: 10-Aug-2000

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4377 – 00 An American National Standard
Designation: MPMS Chapter 10.7
Designation: 356/99
Standard Test Method for
Water in Crude Oils by Potentiometric Karl Fischer Titration
This standard is issued under the fixed designation D 4377; 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.
This test method has been approved by the sponsoring committees and accepted by the cooperating societies in accordance with
established procedures.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 2.2 API Standards:
Manual of Petroleum Measurement Standards (MPMS):
1.1 This test method covers the determination of water in
Chapter 8.1 Manual Sampling of Petroleum and Petroleum
the range from 0.02 to 2 % in crude oils. Mercaptan and sulfide
−
Products
(S or H S) sulfur are known to interfere with this test method
Chapter 8.2 Automatic Sampling of Petroleum and Petro-
(see Section 5).
leum Products
1.2 This test method is intended for use with standard Karl
Chapter 10.2 Determination of Water in Crude Oil by
Fischer reagent or pyridine-free Karl Fischer reagents.
Distillation
1.3 The values stated in SI units are to be regarded as the
standard.
3. Summary of Test Method
1.4 This standard does not purport to address all of the
3.1 After homogenizing the crude oil with a mixer, an
safety concerns, if any, associated with its use. It is the
aliquot of the crude, in a mixed solvent, is titrated to an
responsibility of the user of this standard to establish appro-
electrometric end-point using Karl Fischer reagent.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. Specific precau-
4. Significance and Use
tionary statements are given in Section 7.
4.1 A knowledge of the water content of crude oil is
2. Referenced Documents important in the refining, purchase, sale, or transfer of crude
oils.
2.1 ASTM Standards:
D 1193 Specification for Reagent Water
5. Interferences
D 4006 Test Method for Water in Crude Oil by Distillation
5.1 A number of substances and class of compounds asso-
D 4057 Practice for Manual Sampling of Petroleum and
ciated with condensation or oxidation-reduction reactions in-
Petroleum Products
terfere in the determination of water by Karl Fischer. In crude
D 4177 Practice for Automatic Sampling of Petroleum and
oils, the most common interferences are mercaptans and
Petroleum Products
sulfides. At levels of less than 500 μg/g (ppm) (as sulfur) the
E 203 Test Method for Water Using Volumetric Karl Fischer
interference from these compounds is insignificant. For more
Reagent
information on substances that interfere in the determination of
water using the (Karl Fischer reagent) titration method see Test
This test method is under the jurisdiction of ASTM Committee D02 on
Method E 203.
Petroleum Products and Lubricants and API Committee on Petroleum Measurement
and is the direct responsibility of Subcommittee D02.02, the joint ASTM-API
6. Apparatus
Committee on Static Petroleum Measurement.
Current edition approved Aug. 10, 2000. Published October 2000. Originally
6.1 Karl Fischer Apparatus, using electrometric end-point.
published as D 4377 – 84. Last previous edition D 4377 – 93a.
Annual Book of ASTM Standards, Vol 11.01.
Annual Book of ASTM Standards, Vol 05.02.
Annual Book of ASTM Standards, Vol 15.05. 5
Available from American Petroleum Institute, 1220 L St., NW, Washington, DC
20005-4070.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4377
A suggested assembly of the apparatus is described in Annex 7.4.2 Pyridine-Free Karl Fischer (one-component) reagent
A2. diluted with xylene—Dilute three parts pyridine-free Karl
6.1.1 Presently there is available on the market commercial Fischer (one-component) reagent (1 mL = 5 mg water) to 1
Karl Fischer titration assemblies, some of which automatically part xylene. Fresh Karl Fischer reagent must be used.
stop the titration at the end-point. Instructions for operation of (Warning—See 7.4.1) Must be used with solvent in 7.6.2.
these devices are provided by the manufacturer and not 7.5 Methanol (anhydrous), Maximum 0.1 % water but pref-
described herein. This test method is not intended for use with erably less than 0.05 % water. (Warning—Flammable. Vapor
coulometric Karl Fischer titrators. harmful. May be fatal or cause blindness if swallowed or
6.2 Mixer, to homogenize the crude sample. inhaled. Cannot be made nonpoisonous.)
6.2.1 Non-Aerating, High-Speed, Shear Mixer, capable of 7.6 Sample Solvent—Use 7.6.1 for standard Karl Fischer
meeting the homogenization efficiency test described in Annex reagent containing pyridine and 7.6.2 for pyridine-free Karl
A1. The sample size is limited to that suggested by the Fischer reagent.
manufacturer for the size of the probe. 7.6.1 Sample Solvent—Mix 40 mL of 1-ethylpiperidine, 20
6.3 Syringes: mL of methanol, and 40 mL of Karl Fischer reagent in a
6.3.1 Samples and base liquid are most easily added to the sealable glass bottle. Allow this mixture to sit overnight before
titration vessel by means of accurate glass syringes with LUER adding 200 mL of xylene. Additional methanol may be
fittings and hypodermic needles of suitable length. The bores required in some cases for the proper function of the elec-
of the needles used should be kept as small as possible, but trodes. (Warning—see 7.3.)
large enough to avoid problems arising from back pressure/ 7.6.2 Sample Solvent for Pyridine-Free Reagents—Mix 3
blocking whilst sampling. Suggested syringe sizes are as parts chloroform to 1 part pyridine-free solvent using solvent
follows: part of two-component reagent (contains SO and odorless
6.3.1.1 Syringe, 10 μL, with a needle long enough to dip amine dissolved in methanol) and store in a sealable glass
below the surface of the base solution in the cell during the bottle. An evaluation of a number of crude oils has demon-
standardization procedure (see Section 9). strated that xylene can be substituted for chloroform with no
6.3.1.2 Syringes, 2.5 mL, 5 mL, and 10 mL for crude oil apparent change in accuracy of this test method. (Warning—
samples (see Section 10). Flammable. Vapor harmful.) (Also, see 7.4.1.)
6.3.1.3 Syringe, 20 mL or larger for sample solvent. 7.7 Xylene, reagent grade. Less than 0.05 % water.
7.8 Chloroform, reagent grade. (Warning—Harmful if in-
7. Reagents and Materials
haled or swallowed. Carcinogen (animal positive). Skin and
7.1 Purity of Reagents—Reagent grade chemicals shall be
eye irritant. May produce toxic vapors if burned.
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit- 8. Sampling and Test Samples
tee on Analytical Reagents of the American Chemical Society,
8.1 Sampling, is defined as all the steps required to obtain an
where such specifications are available. Other grades may be
aliquot representative of the contents of any pipe, tank, or other
used, provided it is first ascertained that the reagent is of
system, and to place the sample into the laboratory test
sufficiently high purity to permit its use without lessening the
container. The laboratory test container and sample volume
accuracy of the determination.
shall be of sufficient dimensions and volume to allow mixing as
7.2 Purity of Water—Unless otherwise indicated, references
described in 8.1.2.1.
to water shall be understood to mean reagent water as defined
8.1.1 Laboratory Sample—Only representative samples ob-
by Type IV of Specification D 1193.
tained as specified in Practice D 4057/API MPMS Chapter 8.1
7.3 1-Ethylpiperidine (99 + percent). (Warning—Irritant.
and Practice D 4177/API MPMS Chapter 8.2 shall be used for
Flammable.)
this test method.
7.4 Karl Fischer Reagents, Standard reagent containing
8.1.2 Test Samples—The following sample handling proce-
pyridine (7.4.1) or pyridine-free reagent (7.4.2).
dure shall apply in addition to those covered in 8.1.1.
7.4.1 Karl Fischer Reagent Ethylene Glycol Monomethyl
8.1.2.1 Mix the test sample of crude oil immediately (within
Ether Solution, stabilized, containing pyridine, (1 mL = 5 mg
15 min) before analysis to insure complete homogeneity. Mix
of water)—Fresh Karl Fischer reagent must be used. Must be
the test sample at room temperature (25°C) in the original
used with solvent in 7.6.1. (Warning—Combustible. Harmful
container.
if swallowed, inhaled, or absorbed through the skin.)
NOTE 1—The sample should be mixed at room temperature (25°C) or
less. Mixing of the sample should not increase the temperature of the
The following mixers were used in a cooperative program and have been found
sample more than 10°C, or a loss of water may occur. The type of mixer
satisfactory for samples under 300 mL; Ultra Turrax Model TP 18/10, available
depends on the quantity of crude. Before any unknown mixer is used, the
from Tekmar Co., P. O. Box 37202, Cincinnati, OH 45222; Brinkman Polytron
specifications for the homogenization test, Annex A1, must be met. The
Model PT 35, Available from Brinkman Instruments Inc., Cantiagu Road, Westbury,
NY 11590; and Kraft Apparatus Model S-25, SGA, Bloomfield, NJ.
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not Pyridine-free Karl Fischer reagent and two-component solvent used in the
listed by the American Chemical Society, see Analar Standards for Laboratory cooperative program and found to be satisfactory are available from Crescent
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia Chemical Co., Inc., 1324 Motor Parkway, Hauppauge, NY 11788 under the name of
and National Formulary, U. S. Pharmacopeial Convention, Inc. (USPC), Rockville, Hydranal a registered trademark of Riedel Dehaen—Composite 5 and Hydranal—
MD. solvent.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4377
mixer must be re-evaluated for any changes in the type of crude, quantity
with a paper tissue and reweigh the syringe to 0.1 mg. Titrate
of crude, or shape of the sample container.
the water with Karl Fischer reagent as in 9.3.1.
9.4 Calculate the water equivalence of the Karl Fischer
8.1.2.1.1 For small sample volumes, 50 to 500 mL, a
reagent as follows:
non-aerating, high speed, shear mixer is required. Use the
mixing time, mixing speed, and height above the bottom of the
F 5 W/T (1)
container found to be satisfactory to Annex A1. Clean and dry
where:
the mixer between samples.
F = water equivalence of the Karl Fischer reagent, mg/mL,
8.1.2.2 The test sample size is selected as indicated in Table
W = water added, mg, and
1 based on the expected water content.
T = reagent required for titration of the added water, mL.
9.5 Duplicate values of water equivalence should agree
9. Calibration and Standardization
within 2 % relative. If the variation between the two titrations
9.1 Standardize the Karl Fischer reagent at least once daily.
is greater than 2 % relative, discard the contents of the titration
9.2 Add enough solvent to the clean, dry titration vessel to
vessel. Introduce a further portion of sample solvent into the
cover the electrodes. The volume of solvent depends on the
vessel and repeat the standardization procedure. If the titrations
size of the titration vessel. Seal all openings to the vessel and
for two further portions of distilled water still vary by more
start the magnetic stirrer for a smooth stirring action. Turn on
than 2 %, it is likely that either the Karl Fischer reagent or the
the indicating circuit and adjust the potentiometer to give a
sample solvent, or both, have aged. Replace these with fresh
reference point with approximately 1 μA of current flowing.
reagents and repeat the procedure for calibration and standard-
Add Karl Fischer reagent in suitable amounts to the solvent to
ization.
cause the needle to deflect from the reference point. At first the
9.6 Determine and record the mean water equivalence
needle will deflect due to local concentration of the unreacted
value.
reagent about the electrodes but will fall back to near the
reference point. As the end-point is approached, the needle will
10. Procedure
fall back more slowly after each addition of Karl Fischer
10.1 Add the fresh sample solvent to the titration vessel and
reagent. The end-point is reached when, after the addition of a
bring the solvent to end-point conditions as described in 9.2.
single drop of reagent, the needle remains deflected at least 1
10.2 Add the crude to the titration vessel immediately after
μA from the reference point for at least 30 s. Swirl the titration
the mixing step described in 8.1.2.1 using one of the following
vessel to dry the inside walls of the vessel. Add more Karl
methods:
Fischer reagent, if needed, until a steady end-point is reached
10.2.1 Starting with a clean, dry syringe (10 or 5 mL), rinse
for at least 30 s.
the syringe two times with the sample and discharge to waste.
9.3 Standardize the Karl Fischer reagent with distilled water
Withdraw the required amount of sample and discharge any air
by one of the following methods:
bubbles. Weigh the syringe to the nearest 0.1 mg. Inject the
9.3.1 From a water filled weighing pipet or syringe previ-
sample into the titration vessel, clean the needle with a paper
ously weighed to the nearest 0.1 mg, add 1 drop of distilled
tissue, and reweigh the syringe. Titrate the sample until a
water (about 20 mg) to the sample solvent at end-point
steady end-point for at least 30 s is reached and record the
conditions and reweigh the syringe. Record the weight of the
volume of Karl Fischer reagent to the nearest 0.01 mL (see
water added. Titrate the water with Karl Fischer reagent added
Note 2 and Note 4).
from the buret until a steady end point is reached for at least 30
s. Record to the nearest 0.01 mL the volume of the Karl Fischer
NOTE 4—The solvent should be changed when the sample content
reagent needed to reach the end-point.
exceeds2gof crude per 15 mL of solvent or when 4 mL of titrant per 15
mL of solvent has been added to the titration vessel.
NOTE 2—After
...