ASTM D3590-2017 Standard Test Methods for Total Kjeldahl Nitrogen in Water《水中总凯氏氮含量的标准试验方法》.pdf

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1、Designation: D3590 11D3590 17Standard Test Methods forTotal Kjeldahl Nitrogen in Water1This standard is issued under the fixed designation D3590; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i

2、n parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the determination of total Kjeldahl nitrogen. Section 24 on Quality Control pertains to these testmethods. The follow

3、ing test methods are included:SectionsTest Method AManual Digestion/Distillation 8 13Test Method AManual Digestion/Distillation 8 14Test Method BSemiautomated Colorimetric Bertholt 15 22Test Method BSemiautomated Colorimetric Bertholt 15 231.2 The analyst should be aware that precision and bias stat

4、ements included may not necessarily apply to the water being tested.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use.

5、 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.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationes

6、tablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for R

7、eagent WaterD1426 Test Methods for Ammonia Nitrogen In WaterD2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality

8、 Control Specifications for Standard Test Methods for Water Analysis3. Terminology3.1 DefinitionsDefinitions: For definitions of terms used in these test methods, refer to Terminology D1129.3.1.1 For definitions of terms used in this standard, refer to Terminology D1129.3.2 Definitions of Terms Spec

9、ific to This Standard:3.2.1 continuing calibration blank, na solution containing no analytes (of interest) which is used to verify blank response andfreedom from carryover.3.2.2 continuing calibration verification, na solution (or set of solutions) of known concentration used to verify freedom frome

10、xcessive instrumental drift; the concentration is to cover the range of calibration curve.3.2.3 total Kjeldahl nitrogen, nthe sum of the nitrogen contained in the free ammonia and other nitrogen compounds, whichare converted to ammonium sulfate (NH4)2SO4 under the specified digestion conditions.1 Th

11、ese test methods are under the jurisdiction of ASTM Committee D19 on Water and are the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved April 1, 2011June 1, 2017. Published April 2011June 2017. Originally approved in 1977. Last previous edition

12、approved in 20062011 asD3590 02 (2006).D3590 11. DOI: 10.1520/D3590-11.10.1520/D3590-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summar

13、y page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends t

14、hat users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West

15、 Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 These test methods are useful for measuring organic nitrogen and ammoniacal nitrogen, which are essential growthnutrients.4.2 Nitrogen compounds are widely distributed in the environment. Sources of nitrogen include surface-appli

16、ed fertilizers,cleaning products, and drinking water treatment aids. Because nitrogen is a nutrient for photosynthetic organisms, it may beimportant to monitor and control discharge into the environment.5. Interferences5.1 Nitrate is known to cause a serious negative interference in the test. Report

17、edly, a concentration of 250 mg/L NO3 resultsin zero recovery of some level of mg/L N added as some Nnitrogen compound.5.2 The analyst is cautioned that ammonia in the laboratory may easily become an interference in these test methods fromcontamination of reagents, caps, or from the laboratory atmos

18、phere. Care should be taken that ammonium hydroxide, either as areagent or as a cleaning substance, is not used in the same room.6. Purity of Reagents6.1 Reagent-grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conformto the specification

19、s of the Committee on Analytical Reagents of the American Chemical Society, where such specifications areavailable.3 Other grades may be used, provided it is first ascertained that the reagent is of sufficient high purity to permit its usewithout lessening the accuracy of the determination.6.2 Purit

20、y of WaterUnless otherwise indicated, reference to water shall be understood to mean reagent water conforming toSpecification D1193, Type I. Other reagent water types may be used provided it is first ascertained that the water is of sufficientlyhigh purity to permit its use without adversely affecti

21、ng the precision and bias of the test method. Type III water was specified atthe time of round-robin testing of this test method.7. Sampling and Preservation7.1 Collect the sample in accordance with applicable Practices D3370.7.2 Samples may be preserved up to 28 days by adding concentrated sulfuric

22、 acid to adjust to pH 2 or less and storing atstorebetween 2 and 6C. The preserved sample should be analyzed as soon as possible; data on decomposition are not available.TEST METHOD AMANUAL DIGESTION/DISTILLATION8. Scope8.1 This test method covers the determination of total Kjeldahl nitrogen in wate

23、r. It measures free ammonia or ammonia formedfrom the conversion of nitrogen components of biological origin such as amino acids and proteins. However, the procedure maynot convert the nitrogenous compounds of some wastes to ammonia. Examples of such compounds that may not be measured arenitro compo

24、unds, hydrozones, oximes, nitrates, semicarbazones, pyridines, and some refractory tertiary amines.8.2 Three alternatives are described for the final determination of the ammonia: a titrimetric method, which is applicable toconcentrations above 1 mg N/L; a Nesslerization method, which is applicable

25、to concentrations below 1 mg N/L; and apotentiometric method which is applicable to the range from 0.04 to 1000 mg N/L.8.3 This test method is described for micro and macro systems. Micro determination can be made on sample aliquots containingup to 10 mg of nitrogen.8.1 This test method covers the d

26、etermination of total Kjeldahl nitrogen in water. It measures free ammonia or ammonia formedfrom the conversion of nitrogen components of biological origin such as amino acids and proteins. However, the procedure maynot convert the nitrogenous compounds of some wastes to ammonia. Examples of such co

27、mpounds that may not be measured arenitro compounds, hydrozones, oximes, nitrates, semicarbazones, pyridines, and some refractory tertiary amines.8.2 Three alternatives are described for the final determination of the ammonia: a titrimetric method, which is applicable toconcentrations above 1 mg/L N

28、; a Nesslerization method, which is applicable to concentrations below 1 mg/L N; and apotentiometric method which is applicable to the range from 0.04 to 1000 mg/L N.8.3 This test method is described for micro and macro systems. Micro determination can be made on sample aliquots containingup to 10 m

29、g of nitrogen.3 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, In

30、c. (USPC), Rockville, MD.D3590 1729. Summary of Test Method9.1 The sample is heated in the presence of concentrated H2SO4, K2SO4, and HgSO4, and is digested until SO3 fumes areobtained and the solution becomes colorless or pale yellow. The residue is cooled, diluted, and is treated and alkalized wit

31、h ahydroxide-thiosulfate solution. The ammonia is distilled into a boric acid solution and total Kjeldahl nitrogen is determined bycolorimetry, titrimetry, or potentiometry.10. Apparatus10.1 Digestion ApparatusA Kjeldahl digestion apparatus with 800 to 100-mL1000-mL flasks and suction takeoff to rem

32、oveSO3 fumes and water.10.2 Distillation Apparatus4A macro Kjeldahl flask connected to a condenser and an adaptor so that the distillate can becollected.10.3 Spectrophotometer or Colorimeter, for use at 425 nm with a spectral band path of not more than 6 20 620 nm and a lightpath of 1 cm or longer.1

33、0.4 Electrometer (pH Meter), with expanded millivolt scale, or a specific ion meter.10.5 Ammonia Selective Electrode.510.6 Magnet Stirrer, thermally insulated.11. Reagents and Materials11.1 Ammonia Solution Stock, (1.0 mL = 1.0 mg ammonia nitrogen)Dissolve 3.819 g of ammonium chloride (NH4Cl) inwate

34、r and dilute to 1 L in a volumetric flask with water.11.2 Ammonia Solution, Standard (1.0 mL = 0.01 mg ammonia nitrogen)Dilute 10.0 mL of the stock solution (see 11.1) withwater to 1 L in a volumetric flask.11.3 Boric Acid Solution (2 %)Dissolve 20 g of boric acid (H3BO3) in water and dilute to 1 Lw

35、ith water in a volumetric flask.11.4 Mercuric Sulfate SolutionDissolve 8 g of red mercuric oxide (HgO) in a mixture of 10 mL of sulfuric acid (H2SO4, spgr 1.84) and 40 mLof water, and dilute solution to 100 mL. (WarningMercury has been designated by many regulatory agenciesas a hazardous material th

36、at can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous tohealth and corrosive to materials. Caution should be taken when handling mercury and mercury containing products. See theapplicable product Safety Data Sheet (SDS) for additional information. Users sh

37、ould be aware that selling mercury and/or mercurycontaining products into your state or country may be prohibited by law.)NOTE 1Mercury is a toxic metal and requiresAlternate catalysts such as copper sulfate (CuSO4 special diposal requirements. See Occupational Healthand Safety Act (OSHA) regulation

38、s for specific instructions on handling and disposal of mercury compounds. Alternate catalysts ) may be used but itis the users responsibility to determine the validity of other catalysts.11.5 Mixed Indicator SolutionMix 2 volumes of 0.2 % methyl red in 95 % ethanol with 1 volume of 0.2 % methylene

39、bluein ethanol. Prepare fresh every 30 days.11.6 Methyl Purple Indicator Solution (1 g/L)Dissolve 0.4 g of dimethyl-aminoazobenzene-o-carboxylic acid, sodium salt, inapproximately 300 mL of water. To this solution add 0.55 g of a water-soluble blue dyestuff, Color Index No. 714,dissolve, anddilute t

40、o 1 L with water. This indicator is available commercially in a prepared form.11.7 Nessler ReagentDissolve 100 g of mercuric iodide (HgI2) and 70 g of potassium iodide (KI) in a small volume of water.Add this mixture slowly, with stirring, to a cooled solution of 160 g of sodium hydroxide (NaOH) in

41、500 mL of water. Dilute themixture to 1 L. This solution is stable for at least one year if stored in a thick amber polyethylene bottle out of direct sunlight.(WarningSee 11.4.)NOTE 2Mercury is a toxic metal and requires special diposal requirements. See Occupational Health and Safety Act (OSHA) reg

42、ulations for specificinstructions on handling and disposal of mercury compounds. Alternate reagents may be used but it is the users responsibility to determine the validityof other reagents.11.8 Phenolphthalein Indicator SolutionDissolve 5 g of phenolphthalein in 500 mL of 95 % ethyl alcohol or isop

43、ropanol andadd 500 mL of water. Add NaOH (0.8 g/L) solution dropwise until a faint pink color appears.11.9 Sodium Hydroxide Solution (400 g/L)Dissolve 400 g of NaOH in 800 mL of water, cool, and dilute to 1 L with water.11.10 Sodium Hydroxide Solution (0.8 g/L)Dilute 2 mL of NaOH solution (400 g/L)

44、(see 11.9) with water to 1 L.4 Micro Kjeldahl steam distillation apparatus is commercially available.5 EIL Model 8002-2 of Electronics Instruments Ltd. (U. S. Representative: Cambridge Instrument Co., 73 Spring St., Ossining, NY 10562) has been found satisfactoryfor this purpose. Also, Orion Model 9

45、5-12 has been found satisfactory for this purpose.D3590 17311.11 Sodium Hydroxide-Sodium Thiosulfate SolutionDissolve 500 g of NaOH and 25 g of Na2S2O35H2O in water and diluteto 1 L.11.12 Sulfuric Acid Solution, Standard (0.02 N, 1 mL = 0.28 mg ammonia nitrogen)Prepare a stock solution of approximat

46、ely0.1 N acid by diluting 3 mL of concentrated H2SO4 (sp gr 1.84) to 1 L with water. Dilute 200 mL of this solution to 1 L with water.Standardize the approximately 0.02 N H2SO4 solution against 0.0200 N Na2CO3 solution. This last solution is prepared bydissolving 1.060 g of anhydrous Na2CO3, oven dr

47、ied at 140C, and diluting to 1 L with water.11.13 Digestion SolutionDissolve 267 g of K2SO4 in 1300 mL water and 400 mL of concentrated H2SO4. Add 50 mL ofmercuric sulfate solution (see 11.4) and dilute to 2 L with water. A digestion packet may be used in place of the digestion solutionin the macro

48、Kjeldahl system.12. Procedure12.1 Clean the distillation apparatus with steam before use by distilling a 1 + 1 mixture of water and sodium hydroxide-thiosulfate solution (see 11.11) until the distillate is ammonia-free. Repeat this operation each time the apparatus is out of servicelong enough to ac

49、cumulate ammonia (usually 4 h or more).12.2 Macro Kjeldahl System:12.2.1 Place a measured sample into an 800-mL Kjeldahl flask and dilute to 500 mL. The sample size can be determined usingthe following table:Kjeldahl Nitrogen in Sample,mg/LSample Size,mL0 to 5 5005 to 10 25010 to 20 10020 to 50 50.050 to 500 25.0Prepare a 500-mL reagent water blank.12.2.2 Add 100 mL of digestion solution (see 11.13) (see Note 32) and digest the mixture in the Kjeldahl apparatus until SO3fumes are given off and the solution turns colorless or pale yell