1、Designation:D462910 Designation: D4629 12Designation: 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 desi
2、gnation 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
3、 agencies of the Department of Defense.1. Scope*1.1 This test method covers the determination of the trace total nitrogen naturally found in liquid hydrocarbons boiling in therange from approximately 50 to 400C, with viscosities between approximately 0.2 and 10 cSt (mm2/s) at room temperature. Thist
4、est method is applicable to naphthas, distillates, and oils containing 0.3 to 100 mg/kg total nitrogen. For liquid hydrocarbonscontaining more than 100 mg/kg total nitrogen, Test Method D5762 can be more appropriate. This test method has beensuccessfully applied, during interlaboratory studies, to s
5、ample types outside the range of the scope by dilution of the sample in anappropriate solvent to bring the total nitrogen concentration and viscosity to within the range covered by the test method. However,it is the responsibility of the analyst to verify the solubility of the sample in the solvent
6、and that direct introduction of the dilutedsample by syringe into the furnace does not cause low results due to pyrolysis of the sample or solvent in the syringe needle.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 T
7、his standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. See 6.2, 6.4, 6.5, 6.
8、9, and Section 7.2. Referenced Documents2.1 ASTM Standards:2D1298 Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid PetroleumProducts by Hydrometer MethodD4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital De
9、nsity MeterD5762 Test Method for Nitrogen in Petroleum and Petroleum Products by Boat-Inlet ChemiluminescenceD6299 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate AnalyticalMeasurement System Performance3. Summary of Test Method3.1 The sample of liquid
10、 petroleum hydrocarbon is introduced either by syringe or boat inlet system, into a stream of inert gas(helium or argon). The sample is vaporized and carried to a high temperature zone where oxygen is introduced and organicallybound nitrogen is converted to nitric oxide (NO). The NO contacts ozone,
11、and is converted to excited nitrogen dioxide (NO2). Thelight emitted as the excited NO2decays is detected by a photomultiplier tube and the resulting signal is a measure of the nitrogencontained in the sample.4. Significance and Use4.1 Some process catalysts used in petroleum and chemical refining m
12、ay be poisoned when even trace amounts of nitrogenous1This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.03 onElemental Analysis.Current edition approved July 1, 2010. Published July 2010. Origina
13、lly approved in 1986. Last previous edition approved in 2009 as D462909. DOI: 10.1520/D4629-10.Current edition approved April 15, 2012. Published May 2012. Originally approved in 1986. Last previous edition approved in 2010 as D462910. DOI:10.1520/D4629-12.2For referencedASTM standards, visit theAST
14、M website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an in
15、dication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be
16、 considered the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.materials are contained in the feedstocks. This test method can be used to determine b
17、ound nitrogen in process feeds and may alsobe used to control nitrogen compounds in finished products.5. Apparatus5.1 Furnace, electric, held at a temperature sufficient to volatilize and pyrolyze all of the sample and oxidize the organicallybound nitrogen to NO. Furnace temperature(s) shall be as r
18、ecommended by the manufacturer (typically around 1000C).5.2 Combustion Tube, fabricated to meet the instrument manufacturers specifications.5.3 Drier TubeThe reaction products include water vapor that must be eliminated prior to measurement by the detector. Thiscan be accomplished with a magnesium p
19、erchlorate Mg(ClO4)2scrubber or a membrane drying tube (permeation drier), or bywhatever other means the instrument manufacturer specifies as appropriate for the instrument being used.5.4 Chemiluminescent Detector, capable of measuring light emitted from the reaction between NO and ozone.5.5 Totaliz
20、er, having variable attenuation, and capable of measuring, amplifying, and integrating the current from thechemiluminescent detector. A built in microprocessor or attached computer system may perform these functions.5.6 Micro-litre Syringe, of 5, 10, 25, 50, or 250 L capacity capable of accurately d
21、elivering micro-litre quantities is required.The needle should be long enough to reach the hottest portion of the inlet section of the furnace when injecting the sample. Thesyringe may be part of an automatic sampling and injection device used with the instrument.5.7 Strip Chart Recorder (Optional).
22、5.8 Sample Inlet SystemOne of the following must be used:5.8.1 Manually Operated Syringe.5.8.2 Syringe, with a constant rate injector system, capable of delivering a sample at a precisely controlled rate.5.8.3 Boat Inlet System, to facilitate analysis of samples that would react with the syringe or
23、syringe needle. The pyrolysis tubefor boat inlet use may require specific construction to permit insertion of a boat fully into the inlet section of the furnace. The boatinlet system external to the furnace may be cooled to a temperature below room temperature to aid in dissipating the heat fromthe
24、boat when it is removed from the furnace. Cooling the boat inlet system may also reduce the chances of the sample combustingin the boat before introduction into the furnace and may be necessary when running volatile samples such as naphtha using a boatinlet system.5.9 Quartz Insert Tube (Optional),
25、may be packed with cupric oxide (CuO) or other oxidation catalyst as recommended by theinstrument manufacturer, to aid in completing oxidation. This is inserted into the exit end of the pyrolysis tube.5.10 Vacuum System (Optional), The chemiluminescence detector may be equipped with a vacuum system
26、to maintain thereaction cell at reduced pressure (typically 20 to 25 mm Hg). This can improve the signal to noise ratio of the detector.5.11 Analytical Balance (Optional), with a precision of 60.01 mg.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwi
27、se indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society,3wheresuch specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurit
28、y to permit its use without lessening the accuracy of the determination.6.2 Magnesium Perchlorate Mg(ClO4)2, for drying products of 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 be
29、tter, 99.996 % is recommended). (WarningVigorously accelerates combustion.)6.5 Solvents, for diluting and matrix matching such as, toluene, isooctane, xylene, acetone, cetane. (Other solvents similar tothose occurring in samples to be analyzed are also acceptable). Solvents should contain less than
30、0.1 g N/mL. (WarningFlammable solvents.)6.6 Nitrogen Stock Solution, 1000 g N/mL, Prepare a stock solution by accurately weighing approximately 1.195 g of carbazoleor 0.565 g of pyridine to the nearest milligram, into a tared 100-mL volumetric flask (see 6.6.1). Fifteen millilitres of acetone maythe
31、n be added when using carbazole to help dissolve it. Dilute to volume with the selected solvent. Calculate the exactconcentration of the stock solution based on the actual mass of pyridine or carbazole used and corrected for any known purityfactors for the specific lot of pyridine or carbazole. This
32、 stock may be further diluted to desired nitrogen concentrations.6.6.1 Calibration standards from commercial sources may be used if they conform to the requirements of the test method.NOTE 1Pyridine should be used with low boiling solvents (220C).NOTE 3Working standards should be remixed on a regula
33、r basis depending upon frequency of use and age. Typically, standards have a useful lifeof about 3 months, and should be refrigerated when not being used.3Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, Washington, DC. For suggestions on the testing of reagen
34、ts not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D4629 1226.7 Cupric Oxide Wire, as recommended by instrumen
35、t manufacturer.6.8 Quartz Wool (optional), or other suitable absorbent material that is stable and capable of withstanding temperatures insidethe furnace (Note 4).NOTE 4Materials meeting the requirements in 6.8 are recommended to be used in sample boats to provide a more uniform injection of the sam
36、pleinto the boat by wicking any remaining drops of the sample from the tip of the syringe needle prior to introduction of the sample into the furnace. Consultinstrument manufacturer recommendations for further guidance.6.9 Pyridine.(WarningFlammable, irritant.)6.10 Carbazole.7. Hazards7.1 High tempe
37、rature is employed in this test method. Exercise care when using flammable materials near the pyrolysis furnace.8. Sampling8.1 To preserve volatile components, which may be in some samples, do not uncover samples any longer than necessary.Analyze samples as soon as possible after taking from the bul
38、k supplies to prevent loss of nitrogen or contamination due toexposure or contact with sample container.9. Assembly Apparatus9.1 Assemble apparatus in accordance with manufacturers instructions.9.2 Adjust the gas flows and the pyrolysis temperature as recommended by the instrument manufacturer.10. C
39、alibration and Standardization10.1 Prepare a series of calibration standards from the stock solution (see 6.6) covering the range of operation and consistingof nitrogen type and matrix similar to samples to be analyzed. There shall be a minimum of two calibration standards in additionto the solvent
40、blank, used to generate the calibration curve.10.2 Determine the volume or mass of the material to be analyzed by using one of the volumetric or gravimetric methodsdescribed below.10.2.1 Volumetric measurement of the injected material is obtained by filling the syringe to the 80 % level, retracting
41、theplunger so that the lower liquid meniscus falls on the 10 % scale mark, and recording the volume of liquid in the syringe. Afterthe material has been injected, again retract the plunger so that the lower liquid meniscus falls on the 10 % scale mark and recordthe volume of liquid in the syringe. T
42、he difference between the two volume readings is the volume of material injected.10.2.2 Alternatively, an automatic sampling and injection device may be used to volumetrically inject a reproducible volumeof the material into the furnace.10.2.3 Gravimetric measurement of the injected material is obta
43、ined by weighing the syringe before and after injection todetermine the amount of material injected. This procedure provides greater precision than the volumetric procedure, provided abalance with a precision of at least 60.01 mg is used.10.3 To introduce the sample into the furnace, insert the syri
44、nge needle through the inlet septum up to the syringe barrel andinject the sample or standard at a uniform rate as specified by the instrument manufacturer (typically 0.2 to 1.0 L/s). Rate ofinjection is dependent on such factors as viscosity, hydrocarbon type, and nitrogen concentration. Each user
45、must adopt a methodwhereby a consistent and uniform injection rate is ensured. An automatic sampling and injection device may be used to introducethe material at a reproducible rate. If an automatic sampling and injection device is not being used, determine the quantity ofmaterial injected using eit
46、her 10.2.1 (volumetric injection procedure) or 10.2.3 (gravimetric injection procedure).NOTE 5For the most consistent injection rate and best analytical results, a constant rate injection unit or automatic sampling and injection device maybe helpful. Coke formation at the outlet of the combustion tu
47、be may indicate too rapid of an injection rate. Consult manufacturer for recommendations.NOTE 6With direct injection below 5 mg/kg of nitrogen, the needle septum blank may become increasingly important. Error due to this can beavoided by inserting the syringe needle into the hot inlet and allowing t
48、he needle-septum blank to dissipate before injecting the sample.10.4 If a boat inlet system is used, then the material to be analyzed is injected into a quartz boat using one of the proceduresdescribed in 10.2.1, 10.2.2, or 10.2.3 and the quartz boat is moved into the hot portion of the combustion t
49、ube. Refer to themanufacturers instructions for selecting the rate of boat movement into the furnace and boat residence time in the hot portion ofthe combustion tube.10.5 Calibration curves shall be generated in one of the following manners depending on the capability of the instrumentationused.10.5.1 For systems that use a microprocessor or computer system for data collection and calibration curve generation, thecalibration curve shall be based on the linear regression of a minimum of three repeat measurements of each calibration standard.10.5.2 For those det
