ASTM D3228-96

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.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 3228 – 96 An American National Standard
Standard Test Method for
Total Nitrogen In Lubricating Oils and Fuel Oils By Modified
Kjeldahl Method
This standard is issued under the fixed designation D 3228; 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 standard has been approved for use by agencies of the Department of Defense.
1. Scope sulfate. After digestion, sodium sulfide is added to precipitate
the mercury, and the mixture is made alkaline with caustic.
1.1 This test method is applicable for the determination of
Nitrogen, now in the form of ammonia, is distilled into a boric
nitrogen in lubricating oils when present in the concentration
acid solution. The ammonia is titrated with standard sulfuric
from 0.03 to 0.10 mass %, and for the determination of
acid using methyl purple as an indicator.
nitrogen in fuel oils when present in the concentration from
0.015 to 2.0 mass %. This test method is also applicable to the
4. Significance and Use
analysis of additive concentrates and additive packages.
4.1 The concentration of nitrogen is a measure of the
NOTE 1—This test method may not be applicable to certain materials
presence of nitrogen-containing additives. Knowledge of its
containing N–O or N–N linkage. However, the samples used in the
concentration can be used to predict performance.
cooperative program to establish the precision of the test method were
compounded with currently available ashless additives containing nitro-
5. Apparatus
gen. Complete recovery of the nitrogen present in these additives was
5.1 Buret, 50-mL, graduated in 0.1-mL subdivisions, one for
obtained.
each titrant. Other size burettes may also be used.
1.2 The values given in acceptable SI units are to be
5.2 Flask, Erlenmeyer, 300-mL. Other sizes are also accept-
regarded as the standard.
able.
1.3 This standard does not purport to address all of the
5.3 Heater, electrical or gas.
safety concerns, if any, associated with its use. It is the
5.4 Kjeldahl Distillation Apparatus.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- NOTE 2—Commercially available semi-automatic Kjeldahl apparatus
are acceptable. In such cases manufacturer prescribed sizes of burettes and
bility of regulatory limitations prior to use. For specific
flasks may be used.
precautionary statements, see Note 2, Note 3, Note 5, and Note
6.
5.5 Kjeldahl Flask, at least 500-mL volume.
2. Referenced Documents 6. Reagents
2.1 ASTM Standards:
6.1 Purity of Reagents—Reagent grade chemicals shall be
D 1193 Specification for Reagent Water used in all tests. Unless otherwise indicated, it is intended that
D 4057 Practice for Manual Sampling of Petroleum and all reagents shall conform to the specifications of the Commit-
Petroleum Products
tee on Analytical Reagents of the American Chemical Society,
E 200 Practice for Preparation, Standardization, and Stor- where such specifications are available. Other grades may be
age of Standard and Reagent Solutions for Chemical
used, provided it is first ascertained that the reagent is of
Analysis sufficiently high purity to permit its use without lessening the
accuracy of the determination.
3. Summary of Test Method
6.2 Purity of Water—Unless otherwise indicated, references
3.1 The sample is digested in a mixture of concentrated
to water shall be understood to mean reagent water as defined
sulfuric acid, potassium sulfate, mercuric oxide, and copper
by Types II and III of Specification D 1193.
6.3 Boric Acid Solution (40 g/L)—Dissolve 40 g of boric
This test method is under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee Reagent Chemicals, American Chemical Society Specifications, American
D02.03 on Elemental Analysis.
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Current edition approved Apr. 10, 1996. Published June 1996. Originally listed by the American Chemical Society, see Analar Standards for Laboratory
published as D 3228 – 73. Last previous edition D 3228 – 95. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 11.01. and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 05.02. MD. Other commercial catalyst reagent mixtures that provide equivalent results,
Annual Book of ASTM Standards, Vol 15.05. such as copper and titanium compounds, are also acceptable.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 3228
acid (H BO ) in 1 L of boiling water. 8.3 Warm the contents of the Kjeldahl flask on the digestion
3 3
6.4 Catalyst Reagent —For each test carefully weigh and rack and repeat the swirling. Apply low heat until the frothing
mix 9.9 g of potassium sulfate (K SO ), 0.41 g of mercuric has stopped. Samples that do not froth or char shall be
2 4
oxide (HgO), and 0.08 g of copper sulfate (CuSO ). subjected to a 20-min low-heating period. Careful periodic
6.5 Methyl Purple Indicator Solution —Aqueous solution swirling of the solution in the Kjeldahl flask shall also be made.
containing approximately 0.1 % active constituent (not methyl Gradually apply intermediate heat to raise the temperature of
violet). Other appropriate indicator solutions may also be used. the solution to boiling.
6.6 Sodium Hydroxide Solution (1000 g/L)—Dissolve 1000 8.4 Maintain a minimum volume of 15 mL of liquid in the
g of sodium hydroxide (NaOH) in 1 L of water. (Warning— Kjeldahl flask during the digestion period. Add volumes of 5 to
See Note 2.) 15 mL of H SO (rel dens 1.84) when the volume does not
2 4
conform to this condition. Use the H SO to wash down the
2 4
NOTE 3—Warning: Causes burns. Poison.
neck of the Kjeldahl flask after the contents have been allowed
6.7 Sodium Sulfide Solution (40 g/L)—Dissolve 40 g of
to cool sufficiently so that sulfur trioxide (SO ) fumes have
sodium sulfide (Na S) in warm water 194°F (90°C); cool and
subsided. The volume of H SO (rel dens 1.84) added will
2 4
dilute to 1 L.
depend upon the carbonaceous material in the Kjeldahl flask.
6.8 Sucrose (NIST)—Primary standard grade.
After all of the carbonaceous material has been digested and
6.9 Sulfuric Acid (rel dens 1.84)—Concentrated sulfuric
the solution has cleared, continue the digestion for two more
acid (H SO ). (Warning—See Note 3.)
2 4
hours at rapid rate of boiling. The total volume of liquid
remaining in the Kjeldahl flask after digestion approximates
NOTE 4—Warning: Causes severe burns. Strong oxidizer.
the volume in the Kjeldahl flask for the blank.
6.10 Sulfuric Acid, Standard (0.05 M)—Slowly add 3 mL
of concentrated sulfuric acid (H SO , rel dens 1.84) to 500 mL NOTE 6—For some samples, a two hour digestion period may be
2 4
unnecessary, if the solution has completely cleared.
of water in a suitable size beaker. Mix the acid and water; allow
it to cool and transfer to a 1-L volumetric flask. Dilute to the
8.5 Turn off the heat, but allow the Kjeldahl flask to remain
mark with water; mix well. Standardize sulfuric acid to the
in the fume duct or hood until the evolution of SO fumes has
nearest 0.0005 mol/L against 0.1 mol/L NaOH solution using
subsided. Remove the Kjeldahl flask from the rack and cool to
phenolphthalein indicator. Standardize the NaOH solution
approximately room temperature.
against primary standard grade potassium hydrogen phthalate
8.6 Place a 300-mL receiving flask containing 25 mL of
(HOOCC H COOK). Use the procedure outlined in Sections
H BO solution and 5 drops of methyl purple indicator solution
6 4
3 3
14 to 19 of Practice E 200.
under the condenser with the delivery tube tip extending to the
bottom of the receiving flask.
NOTE 5—Commercially available pre-standardized H SO and NaOH
2 4
8.7 Measure approximately 275 mL of water and add a
solutions may be used.
portion of this water to the Kjeldahl flask and swirl the contents
6.11 Sulfuric Acid (0.005 M)—Prepare b
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