1、Designation: D4629 12 (Reapproved 2017)Designation: 379/88Standard Test Method forTrace Nitrogen in Liquid Petroleum Hydrocarbons bySyringe/Inlet Oxidative Combustion and ChemiluminescenceDetection1This standard is issued under the fixed designation D4629; the number immediately following the design
2、ation indicates the year oforiginal adoption or, in the case 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 a
3、gencies of the U.S. Department of Defense.1. Scope1.1 This test method covers the determination of the tracetotal nitrogen naturally found in liquid hydrocarbons boiling inthe range from approximately 50 C to 400 C, with viscositiesbetween approximately 0.2 cSt and 10 cSt (mm2/s) at roomtemperature.
4、 This test method is applicable to naphthas,distillates, and oils containing 0.3 mg kg to 100 mg kg totalnitrogen. For liquid hydrocarbons containing more than100 mg kg total nitrogen, Test Method D5762 can be moreappropriate. This test method has been successfully applied,during interlaboratory stu
5、dies, to sample types outside therange of the scope by dilution of the sample in an appropriatesolvent to bring the total nitrogen concentration and viscosityto within the range covered by the test method. However, it isthe responsibility of the analyst to verify the solubility of thesample in the s
6、olvent and that direct introduction of the dilutedsample by syringe into the furnace does not cause low resultsdue to pyrolysis of the sample or solvent in the syringe needle.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1
7、.3 This standard does not purport to address all of thesafety concerns, if any, associated with 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. See 6.2, 6.4, 6
8、.5,6.9, and Section 7.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organizatio
9、n TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1298 Test Method for Density, Relative Density, or APIGravity of Crude Petroleum and Liquid Petroleum Prod-ucts by Hydrometer MethodD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by D
10、igital Density MeterD5762 Test Method for Nitrogen in Petroleum and Petro-leum Products by Boat-Inlet ChemiluminescenceD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System Performance3. Summary of Test Method3.1 The sample
11、of liquid petroleum hydrocarbon is intro-duced either by syringe or boat inlet system, into a stream ofinert gas (helium or argon). The sample is vaporized andcarried to a high temperature zone where oxygen is introducedand organically bound nitrogen is converted to nitric oxide(NO). The NO contacts
12、 ozone, and is converted to excitednitrogen dioxide (NO2). The light emitted as the excited NO2decays is detected by a photomultiplier tube and the resultingsignal is a measure of the nitrogen contained in the sample.4. Significance and Use4.1 Some process catalysts used in petroleum and chemicalref
13、ining may be poisoned when even trace amounts of nitrog-enous materials are contained in the feedstocks. This testmethod can be used to determine bound nitrogen in processfeeds and may also be used to control nitrogen compounds infinished products.1This test method is under the jurisdiction of ASTM
14、Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved July 1, 2017. Published July 2017. Originally approvedin 1986. Last previous edition approved in 2012 as D4629 12. DOI: 10.1520/D4629
15、-12R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, P
16、O Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued
17、by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15. Apparatus5.1 Furnace, electric, held at a temperature sufficient tovolatilize and pyrolyze all of the sample and oxidize theorganically bound nitrogen to NO. Furnace temperature(s)shall be as recommended by the manufactu
18、rer (typicallyaround 1000 C).5.2 Combustion Tube, fabricated to meet the instrumentmanufacturers specifications.5.3 Drier TubeThe reaction products include water vaporthat must be eliminated prior to measurement by the detector.This can be accomplished with a magnesium perchlorateMg(ClO4)2scrubber o
19、r a membrane drying tube (permeationdrier), or by whatever other means the instrument manufacturerspecifies as appropriate for the instrument being used.5.4 Chemiluminescent Detector, capable of measuring lightemitted from the reaction between NO and ozone.5.5 Totalizer, having variable attenuation,
20、 and capable ofmeasuring, amplifying, and integrating the current from thechemiluminescent detector. A built in microprocessor or at-tached computer system may perform these functions.5.6 Micro-litre Syringe, of 5 L, 10 L, 25 L, 50 L, or250 L capacity capable of accurately delivering micro-litrequan
21、tities is required. The needle should be long enough toreach the hottest portion of the inlet section of the furnacewhen injecting the sample. The syringe may be part of anautomatic sampling and injection device used with the instru-ment.5.7 Strip Chart Recorder (Optional).5.8 Sample Inlet SystemOne
22、 of the following must beused:5.8.1 Manually Operated Syringe.5.8.2 Syringe, with a constant rate injector system, capableof delivering a sample at a precisely controlled rate.5.8.3 Boat Inlet System, to facilitate analysis of samples thatwould react with the syringe or syringe needle. The pyrolysis
23、tube for boat inlet use may require specific construction topermit insertion of a boat fully into the inlet section of thefurnace. The boat inlet system external to the furnace may becooled to a temperature below room temperature to aid indissipating the heat from the boat when it is removed from th
24、efurnace. Cooling the boat inlet system may also reduce thechances of the sample combusting in the boat before introduc-tion into the furnace and may be necessary when runningvolatile samples such as naphtha using a boat inlet system.5.9 Quartz Insert Tube (Optional), may be packed withcupric oxide
25、(CuO) or other oxidation catalyst as recom-mended by the instrument manufacturer, to aid in completingoxidation. This is inserted into the exit end of the pyrolysistube.5.10 Vacuum System (Optional), The chemiluminescencedetector may be equipped with a vacuum system to maintainthe reaction cell at r
26、educed pressure (typically 20 mm to25 mm Hg). This can improve the signal to noise ratio of thedetector.5.11 Analytical Balance (Optional), with a precision of60.01 mg.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thata
27、ll reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society,3where such specifications are available. Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lesseni
28、ng theaccuracy of the determination.6.2 Magnesium Perchlorate Mg(ClO4)2, for drying productsof combustion (if permeation drier is not used.) (WarningStrong oxidizer, irritant.)6.3 Inert Gas, argon or helium, ultra-high purity grade(UHP).6.4 Oxygen, (99.8 % or better, 99.996 % is recommended).(Warnin
29、gVigorously accelerates combustion.)6.5 Solvents, for diluting and matrix matching such as,toluene, isooctane, xylene, acetone, cetane. (Other solventssimilar to those occurring in samples to be analyzed are alsoacceptable). Solvents should contain less than 0.1 g N/mL.(WarningFlammable solvents.)6.
30、6 Nitrogen Stock Solution, 1000 g N/mL, Prepare a stocksolution by accurately weighing approximately 1.195 g ofcarbazole or 0.565 g of pyridine to the nearest milligram, intoa tared 100 mL volumetric flask (see 6.6.1). Fifteen millilitresof acetone may then be added when using carbazole to helpdisso
31、lve it. Dilute to volume with the selected solvent. Calcu-late the exact concentration of the stock solution based on theactual mass of pyridine or carbazole used and corrected for anyknown purity factors for the specific lot of pyridine orcarbazole. This stock may be further diluted to desired nitr
32、ogenconcentrations.6.6.1 Calibration standards from commercial sources maybe used if they conform to the requirements of the test method.NOTE 1Pyridine should be used with low boiling solvents (220 C).NOTE 3Working standards should be remixed on a regular basisdepending upon frequency of use and age
33、. Typically, standards have auseful life of about 3 months, and should be refrigerated when not beingused.6.7 Cupric Oxide Wire, as recommended by instrumentmanufacturer.6.8 Quartz Wool (optional), or other suitable absorbentmaterial that is stable and capable of withstanding temperaturesinside the
34、furnace (Note 4).NOTE 4Materials meeting the requirements in 6.8 are recommendedto be used in sample boats to provide a more uniform injection of the3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents not
35、listed by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D4629 12 (2017)2sample into the boat by wicking any remaining drops
36、 of the sample fromthe tip of the syringe needle prior to introduction of the sample into thefurnace. Consult instrument manufacturer recommendations for furtherguidance.6.9 Pyridine. (WarningFlammable, irritant.)6.10 Carbazole.7. Hazards7.1 High temperature is employed in this test method.Exercise
37、care when using flammable materials near the pyroly-sis furnace.8. Sampling8.1 To preserve volatile components, which may be in somesamples, do not uncover samples any longer than necessary.Analyze samples as soon as possible after taking from the bulksupplies to prevent loss of nitrogen or contamin
38、ation due toexposure or contact with sample container.9. Assembly Apparatus9.1 Assemble apparatus in accordance with manufacturersinstructions.9.2 Adjust the gas flows and the pyrolysis temperature asrecommended by the instrument manufacturer.10. Calibration and Standardization10.1 Prepare a series
39、of calibration standards from the stocksolution (see 6.6) covering the range of operation and consist-ing of nitrogen type and matrix similar to samples to beanalyzed. There shall be a minimum of two calibrationstandards in addition to the solvent blank, used to generate thecalibration curve.10.2 De
40、termine the volume or mass of the material to beanalyzed by using one of the volumetric or gravimetricmethods described below.10.2.1 Volumetric measurement of the injected material isobtained by filling the syringe to the 80 % level, retracting theplunger so that the lower liquid meniscus falls on t
41、he 10 %scale mark, and recording the volume of liquid in the syringe.After the material has been injected, again retract the plungerso that the lower liquid meniscus falls on the 10 % scale markand record the volume of liquid in the syringe. The differencebetween the two volume readings is the volum
42、e of materialinjected.10.2.2 Alternatively, an automatic sampling and injectiondevice may be used to volumetrically inject a reproduciblevolume of the material into the furnace.10.2.3 Gravimetric measurement of the injected material isobtained by weighing the syringe before and after injection todet
43、ermine the amount of material injected. This procedureprovides greater precision than the volumetric procedure,provided a balance with a precision of at least 60.01 mg isused.10.3 To introduce the sample into the furnace, insert thesyringe needle through the inlet septum up to the syringe barreland
44、inject the sample or standard at a uniform rate as specifiedby the instrument manufacturer (typically 0.2 L s to1.0 L s). Rate of injection is dependent on such factors asviscosity, hydrocarbon type, and nitrogen concentration. Eachuser must adopt a method whereby a consistent and uniforminjection r
45、ate is ensured. An automatic sampling and injectiondevice may be used to introduce the material at a reproduciblerate. If an automatic sampling and injection device is not beingused, determine the quantity of material injected using either10.2.1 (volumetric injection procedure) or 10.2.3 (gravimetri
46、cinjection procedure).NOTE 5For the most consistent injection rate and best analyticalresults, a constant rate injection unit or automatic sampling and injectiondevice may be helpful. Coke formation at the outlet of the combustiontube may indicate too rapid of an injection rate. Consult manufacturer
47、 forrecommendations.NOTE 6With direct injection below 5 mg kg of nitrogen, the needleseptum blank may become increasingly important. Error due to this can beavoided by inserting the syringe needle into the hot inlet and allowing theneedle-septum blank to dissipate before injecting the sample.10.4 If
48、 a boat inlet system is used, then the material to beanalyzed is injected into a quartz boat using one of theprocedures described in 10.2.1, 10.2.2,or10.2.3 and the quartzboat is moved into the hot portion of the combustion tube.Refer to the manufacturers instructions for selecting the rate ofboat m
49、ovement into the furnace and boat residence time in thehot portion of the combustion tube.10.5 Calibration curves shall be generated in one of thefollowing manners depending on the capability of the instru-mentation used.10.5.1 For systems that use a microprocessor or computersystem for data collection and calibration curve generation, thecalibration curve shall be based on the linear regression of aminimum of three repeat measurements of each calibrationstandard.10.5.2 For those detectors not equipped with a micropro-cessor or computer system for g
