1、Designation: D3228 08 (Reapproved 2014)Standard Test Method forTotal Nitrogen in Lubricating Oils and Fuel Oils by ModifiedKjeldahl Method1This standard is issued under the fixed designation D3228; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This
3、test method covers the determination of nitrogen inlubricating oils when present in the concentration from 0.03 to0.10 mass %, and for the determination of nitrogen in fuel oilswhen present in the concentration from 0.015 to 2.0 mass %.This test method is also applicable to the analysis of additivec
4、oncentrates and additive packages.NOTE 1This test method may not be applicable to certain materialscontaining NO or NN linkage. However, the samples used in thecooperative program to establish the precision of the test method werecompounded with currently available ashless additives containing nitro
5、-gen. Complete recovery of the nitrogen present in these additives wasobtained.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with
6、its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificwarning statements, see 6.6, 6.9, and 8.8.2. Referenced Documents2.1 ASTM Standards:2D1193 Specific
7、ation for Reagent WaterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceE200 Practice for Preparation, Standardization, and Storageof Stand
8、ard and Reagent Solutions for Chemical Analysis3. Summary of Test Method3.1 The sample is digested in a mixture of concentratedsulfuric acid, potassium sulfate, mercuric oxide, and coppersulfate. After digestion, sodium sulfide is added to precipitatethe mercury, and the mixture is made alkaline wit
9、h caustic.Nitrogen, now in the form of ammonia, is distilled into a boricacid solution. The ammonia is titrated with standard sulfuricacid using methyl purple as an indicator.4. Significance and Use4.1 The concentration of nitrogen is a measure of thepresence of nitrogen-containing additives. Knowle
10、dge of itsconcentration can be used to predict performance.5. Apparatus5.1 Buret, 50-mL, graduated in 0.1-mLsubdivisions, one foreach titrant. Other size burettes may also be used.5.2 Flask, Erlenmeyer, 300-mL. Other sizes are also accept-able.5.3 Heater, electrical or gas.5.4 Kjeldahl Distillation
11、Apparatus.NOTE 2Commercially available semiautomatic Kjeldahl apparatus areacceptable. In such cases manufacturer prescribed sizes of burettes andflasks may be used.5.5 Kjeldahl Flask, at least 500-mL volume.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless o
12、therwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct res
13、ponsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved May 1, 2014. Published July 2014. Originally approvedin 1973. Last previous edition approved in 2008 as D3228 08. DOI: 10.1520/D3228-08R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact
14、ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consh
15、ohocken, PA 19428-2959. United States1where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated,
16、referencesto water shall be understood to mean reagent water as definedby Types II and III of Specification D1193.6.3 Boric Acid Solution (40 g/L)Dissolve 40 g of boricacid (H3BO3) in 1 L of boiling water.6.4 Catalyst Reagent4For each test carefully weigh andmix 9.9 g of potassium sulfate (K2SO4), 0
17、.41 g of mercuricoxide (HgO), and 0.08 g of copper sulfate (CuSO4).6.5 Methyl Purple Indicator Solution5Aqueous solutioncontaining approximately 0.1 % active constituent (not methylviolet). Other appropriate indicator solutions may also be used.6.6 Sodium Hydroxide Solution (1000 g/L)Dissolve1000 g
18、of sodium hydroxide (NaOH) in 1 L of water.(WarningCauses burns. Poison.)6.7 Sodium Sulfide Solution (40 g/L)Dissolve 40 g ofsodium sulfide (Na2S) in warm water 194F (90C); cool anddilute to 1 L.6.8 Sucrose (NIST)Primary standard grade.6.9 Sulfuric Acid (rel dens 1.84)Concentrated sulfuricacid (H2SO
19、4). (WarningCauses severe burns. Strong oxi-dizer.)6.10 Sulfuric Acid, Standard (0.05 M)Slowly add 3 mL ofconcentrated sulfuric acid (H2SO4, rel dens 1.84) to 500 mL ofwater in a suitable size beaker. Mix the acid and water; allowit to cool and transfer to a 1-L volumetric flask. Dilute to themark w
20、ith water; mix well. Standardize sulfuric acid to thenearest 0.0005 mol/L against 0.1 mol/L NaOH solution usingphenolphthalein indicator. Standardize the NaOH solutionagainst primary standard grade potassium hydrogen phthalate(HOOCC6H4COOK). Use the procedure outlined in Sections14 to 19 of Practice
21、 E200.NOTE 3Commercially available pre-standardized H2SO4and NaOHsolutions may be used.6.11 Sulfuric Acid (0.005 M)Prepare by tenfold dilutionof the standard 0.05 M sulfuric acid prepared and standardizedin 6.10.6.12 Quality Control (QC) Sample, preferably are portionsof one or more liquid petroleum
22、 materials that are stable andrepresentative of the samples of interest. These QC samplescan be used to check the validity of the testing process asdescribed in Section 10.7. Sampling7.1 Take the sample in accordance with the instructions inPractice D4057.7.2 Ensure that the sample is thoroughly rep
23、resentative ofthe material to be tested and that the portion of the sample usedfor test is thoroughly representative of the whole sample.8. Procedure8.1 Transfer 1.0 to 1.5 g of sample, weighed to the nearest0.1 mg, into a Kjeldahl flask. Avoid contact of the sample withthe neck of the Kjeldahl flas
24、k.Add the catalyst reagent mixtureto the Kjeldahl flask. Add two or three beads to preventbumping.8.2 Wash down the neck of the Kjeldahl flask with 20 mL ofH2SO4(rel dens 1.84). Swirl the contents of the Kjeldahl flaskto facilitate the mixing of the sample, catalyst reagent, andH2SO4.8.3 Warm the co
25、ntents of the Kjeldahl flask on the digestionrack and repeat the swirling. Apply low heat until the frothinghas stopped. Samples that do not froth or char shall besubjected to a 20-min low-heating period. Careful periodicswirling of the solution in the Kjeldahl flask shall also be made.Gradually app
26、ly intermediate heat to raise the temperature ofthe solution to boiling.8.4 Maintain a minimum volume of 15 mL of liquid in theKjeldahl flask during the digestion period.Add volumes of 5 to15 mL of H2SO4(rel dens 1.84) when the volume does notconform to this condition. Use the H2SO4to wash down then
27、eck of the Kjeldahl flask after the contents have been allowedto cool sufficiently so that sulfur trioxide (SO3) fumes havesubsided. The volume of H2SO4(rel dens 1.84) added willdepend upon the carbonaceous material in the Kjeldahl flask.After all of the carbonaceous material has been digested andth
28、e solution has cleared, continue the digestion for two morehours at rapid rate of boiling. The total volume of liquidremaining in the Kjeldahl flask after digestion approximatesthe volume in the Kjeldahl flask for the blank.NOTE 4For some samples, a two hour digestion period may beunnecessary, if th
29、e solution has completely cleared.8.5 Turn off the heat, but allow the Kjeldahl flask to remainin the fume duct or hood until the evolution of SO3fumes hassubsided. Remove the Kjeldahl flask from the rack and cool toapproximately room temperature.8.6 Place a 300-mL receiving flask containing 25 mL o
30、fH3BO3solution and 5 drops of methyl purple indicator solutionunder the condenser with the delivery tube tip extending to thebottom of the receiving flask.8.7 Measure approximately 275 mL of water and add aportion of this water to the Kjeldahl flask and swirl the contents3Reagent Chemicals, American
31、 Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.
32、S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4The sole source of supply of commercially prepared catalyst reagent mixture,brand name Kel-Pak #1, known to the committee at this time is Matheson Scientific,1850 Greenleaf Ave., Elk Grove Village, IL 60007. If you are aware of alternativesuppl
33、iers, please provide this information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.5Fleisher Methyl Purple Indicator, U.S. Patent No. 241669, may be obtainedfrom Harry Fleisher Chemical Co
34、., Benjamin Franklin Station, Washington, DC20004, or from any chemical supply company handling Fleisher Methyl Purple.D3228 08 (2014)2until the salt cake has dissolved (Note 2).Add the remainder ofthe water and cool the contents of the Kjeldahl flask to roomtemperature.NOTE 5It can be necessary to
35、warm the contents in the Kjeldahl flaskto facilitate solution of the salt cake.8.8 Add 25 mL of Na2S solution to the cooled contents ofthe Kjeldahl flask, to precipitate the mercury, and swirl to mix.(WarningIn addition to other precautions, when the Na2Ssolution is added to the cooled digestion fla
36、sk, considerablehydrogen sulfide is evolved. Therefore, conduct 8.8 and 8.9 ina hood with a suitable draft.) (Warning In addition to otherprecautions, care must be exercised in the disposal of themercuric sulfide. Laboratories processing large volumes ofKjeldahl nitrogen determinations should consid
37、er the use of arecovery trap for mercury.)8.9 Place the Kjeldahl flask in a slurry of ice and water. Coolthe contents in the Kjeldahl flask to approximately 40F(4.5C). Slowly add 75 mL of NaOH solution (1000 g/L) downthe inclined neck of the Kjeldahl flask, without agitation, toform two layers.8.9.1
38、 Carefully remove the Kjeldahl flask from the ice bathso that mixing of the layers does not occur. Carefully place theKjeldahl flask on the Kjeldahl distillation rack.8.9.2 Immediately connect the Kjeldahl flask to the distilla-tion apparatus and mix the contents of the Kjeldahl flaskthoroughly by s
39、wirling. The digestion flask must be connectedto the distillation apparatus immediately after the alkali hasbeen added and layered, but before swirling to mix the acid andalkali. When any mixing is permitted to occur before thedigestion flask is connected, the heat generated can be suffi-cient to re
40、lease some of the ammonia which can be lost. Thisloss results in low recovery of ammonia, and thus low valuesfor the nitrogen content of the sample.8.10 Promptly apply full heat to the digestion flask. Reducethe heat just before the solution begins to boil and maintain atlow boiling for 5 min. Heat
41、must be applied promptly toprevent sucking of the H3BO3solution into the condenser asthe digestion solution cools. The initial distillation rate mustnot be too rapid because most of the ammonia is distilledduring the first few minutes, and if too large an amount ispresent it can not all be absorbed
42、in the H3BO3solution.Increase the heat to rapid boiling, until the volume in thereceiving flask reaches a volume of approximately 130 mL.8.11 Lower the receiving flask to expose the condenserdelivery tube tip. Rinse the tip with water. After approximately1 min of additional distillation, turn off th
43、e heat and allow thecondenser to drain.NOTE 6The total volume in the receiving flask is approximately 150mL. For convenience the receiving flask can be marked at the 130 and150-mL volume points.NOTE 7Commercially available digestiondistillation apparatus maybe used as long as the same chemical react
44、ions occurring in Section 8 aremaintained. In such cases, follow the manufacturers instructions for thedetails of digestion and distillation sequences.8.12 Titrate the contents in the receiving flask with standardH2SO4(0.005 M) to an end point where the gray color of thesolution just disappears and
45、only the purple color remains. Ifthe titration exceeds 50 mL, continue the titration with standardH2SO4(0.05 M). Read the volume of the standard acid to thenearest 0.05 mL.NOTE 8Commercially available automated colorimetric titrators maybe used instead of the manual titration described in 8.12.8.13
46、Determine a blank with every set of samples, identicalin every way with the regular determinations, except 1.0 g ofsucrose is added in place of the sample. The initial volume of20 mL of H2SO4(rel dens 1.84) is all that is used for thedigestion of the sucrose.9. Calculation9.1 Calculate the nitrogen
47、content of the sample as follows:Nitrogen content, mass % 5 A 2 B! 3 M11C 3 M2# 32 30.014013100/W (1)where:A = millilitres of 0.005 M H2SO4required to titratethe sample,B = millilitres of 0.005 M H2SO4required to titratethe blank,C = millilitres of 0.05 M H2SO4required to titrate thesample,M1 = 0.00
48、5 (molarity of 0.005 M H2SO4),M2 = 0.05 (molarity of 0.05 M H2SO4),2 = number of equivalents of H2SO4,0.01401 = equivalent weight, g/mL,100 = factor to convert to percent, andW = weight of sample used, g.9.2 Alternatively, calculate the nitrogen content of thesample as follows:Nitrogen content, mass
49、 % 5 A 2 B! 30.011C 30.1# 30.014013100/W (2)where:A = millilitres of 0.005 M H2SO4required to titratethe sample,B = millilitres of 0.005 M H2SO4required to titratethe blank,C = millilitres of 0.05 M H2SO4required to titrate thesample,0.01 = normality of 0.005 M H2SO4,0.01401 = equivalent weight, g/mL,100 = factor to convert to percent, andW = weight of sample used, g.10. Quality Control10.1 Confirm the performance of the instrument or the testprocedure by analyzing a quality control (QC) sample (6.12).10.1.1 When QC/Quality Assurance (QA) protocols
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