1、Designation: D2973 101D2973 16Standard Test Method forTotal Nitrogen in Peat Materials1This standard is issued under the fixed designation D2973; 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 NOTEEditorially corrected the jurisdiction in March 2011.1. Scope*1.1 This test method covers a chemical test method for the determination of the weightm
3、ass percent of nitrogen in peat material.1.2 UnitsThe values stated in SI units are to be regarded as standard. No other units of measurement are included in thisstandard.1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practic
4、eD6026.1.3.1 The procedures used to specify how data are collected/recorded or calculated in this standard are regarded as the industrystandard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do notconsider material variation, pu
5、rpose for obtaining the data, special purpose studies, or any considerations for the users objectives;and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations.It is beyond the scope of this standard to consider significant digit
6、s used in analysis methods for engineering design.1.4 This 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 re
7、gulatorylimitations prior to use.(See Practice D3740)2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and Contained FluidsD1193 Specification for Reagent WaterD2974 Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic SoilsD3740 Practice for
8、 Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4753 Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and ConstructionMaterials TestingD6026 Practice for Using Si
9、gnificant Digits in Geotechnical DataE145 Specification for Gravity-Convection and Forced-Ventilation Ovens3. Terminology3.1 Definitions:3.1.1 For common definitions of common technical terms in this standard, refer to Terminology D653.4. Summary of Test Method4.1 In this procedure,method, the nitro
10、gen is converted into ammonium salts by destructive digestion of the samplespecimenwith a hot, catalyzed mixture of concentrated sulfuric acid and potassium sulfate. These salts are subsequently decomposed in ahot alkaline solution from which the ammonia is recovered by distillation and finally dete
11、rmined by acidimetric titration.1 This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.22 on Soil as a Medium forPlant Growth.Current edition approved Oct. 1, 2010July 1, 2016. Published November 2010July 2016. Origina
12、lly approved in 1971. Last previous edition approved in 2004 asD297371(2004). Withdrawn in 2009 and reinstated in 2010 as D2973101 10. DOI: 10.1520/D2973-10E01 DOI: 10.1520/D2973-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.or
13、g. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary 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
14、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 considered the official document.*A Summary of Changes section appears at
15、the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 Nitrogen content is important as it is one of the primary plant food elements necessary for plant growth. Nitrogen is contentof peat is
16、 necessary to make sure an adequate, but not excessive amount of fertility is supplied to the target plant. Nitrogen ispresent in peat as organic nitrogen, and therefore, does not release nitrogen to plants as quickly as chemical fertilizers. However,nitrogen from peat continues to be released for s
17、everal years as the organic matter decomposes.NOTE 1The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of theequipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered c
18、apable of competent and objectivetesting/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results.Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.6. Appara
19、tus6.1 For DigestionUse Kjeldahl flasks of hard, moderately thick, well-annealed glass with total capacity of about 800 mL.Conduct digestion over a heating device adjusted to bring 250 mL of Type III water at 25C to a rolling boil in about 5 min.6.2 For DistillationUse 800-mL Kjeldahl flasks fitted
20、with rubber stoppers through which passes the lower end of an efficientscrubber bulk or trap to prevent mechanical carry-over of sodium hydroxide solution during distillation. Connect the upper endof the bulb tube to the condenser tube by rubber tubing. Trap the outlet of the condenser in such a way
21、 as to ensure make surecomplete absorption of ammonia distilled over into the acid in the receiver.6.3 Erlenmeyer Flask, Flask 250 or 300-mL capacity.A glass flask having a capacity of 250 or 300-mL.6.4 OvenThermostatically controlled oven capable of maintaining a uniform temperature of 110 6 5C thr
22、oughout the dryingchamber. Specification E145 provides information regarding the specification of ovens.6.5 BalanceBalances shall conform to the requirements of Specification D4753 and having a readability without estimationto 0.01 g for moisture content determinations and 0.001 g for mass determina
23、tions. The capacity of the balance shall exceed themass of the container plus specimen.6.6 Mortar and Pestle (Optional)Apparatus suitable for crushing soft lumps.6.7 CylinderA glass cylinder with an indication mark at 1,000 6 5 mL used for mixing reagents.6.8 Miscellaneous ItemsItems such as spatula
24、s, dishes, stirring rods, and wash bottle may be useful7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical
25、 Society, wheresuch specifications are available.3 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination. All water used for this test method shall be ASTMType III or better as d
26、efined in Specification D1193.7.2 Type III WaterUnless otherwise indicated, references to water shall be understood to mean reagent water as defined byType III of Specification D1193.7.3 Boric Acid Solution, 4 %Solution (H3BO3), 4 %, (40 g/L)Dissolve 40 g of boric acid (H3BO3) in Type III water and
27、diluteto 1 L.7.4 Mercuric Oxide Tablets (HgO).7.5 Methyl RedDissolve 200 mg of methyl red in 100 mL of alcohol.7.6 Methyl BlueDissolve 200 mg of methyl blue in 100 mL of alcohol.7.7 Mixed IndicatorDissolve 200 mg of methyl red in 100 mL of alcohol. Dissolve 200 mg methylene blue in 100 mL ofalcohol.
28、 Mix in a ratio of 1 part methyl red to 2 parts methylene blue.7.8 Potassium Sulfate (K2SO4).7.9 Potassium Sulfide Solution (K2S), (40 g/L)Dissolve 40 g of potassium sulfide in Type III water and dilute to 1 L.7.10 Sodium Hydroxide Solution (NaOH), (450 g/L)Dissolve 450 g of nitrate-free sodium hydr
29、oxide (NaOH) inType III waterand dilute to 1 L. The specific gravity of the solution should be 1.36 or greater.7.11 Sulfuric Acid (H2SO4), (sp gr 1.84)Concentrated sulfuric acid (Hacid.2SO4).7.12 Sulfuric Acid, Standard (0.1 to 0.3 N)Dissolve 3.0 to 9.0 mL of sulfuric acid (H2SO4) in Type III water
30、and dilute to 1L.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, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the Unit
31、ed States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D2973 1627.13 Zinc, Zinc30 mesh.8. Hazards8.1 WarningMercury has been designated by many regulatory agencies as a hazardous material that can cause serious medicalissues. Mercury, or its vapor, ma
32、y be hazardous to health and corrosive to materials. Caution should be taken when handlingmercury containing products. See the applicable product Safety Data Sheet (SDS) for additional. Users should be aware that sellingmercury or mercury containing products into your state or country may be prohibi
33、ted by law.9. Preparation of Sample Sampling and Test Specimens9.1 Obtain a sample as outlined in Section 7 of Test Methods D2974.9.2 Air-dry the sample in accordance with Method II B, 8.1.3.2 of Test Methods D2974. Record the percentage of moistureremoved by air-drying. (See Specification (air drie
34、d portion only). Determine and record the moisture removed during air-dryingas a E145)percentage of the as-received mass to the nearest 0.1 %.9.3 Thoroughly mix the air-dried specimen and obtain the equivalent of 10.0 g of test specimen on the as-received basis.Determine and record this mass to the
35、nearest 0.001 g. Calculate the grams of air-dried equivalent specimen mass as follows tothe nearest 0.1 g:air-dried equivalent specimen mass, g510.0210.0 3 moisture removed %!100 (1)10. Procedure10.1 Mix thoroughly the air-dried, ground sample and weigh to the nearest 1 mg the equivalent of 10.0 g o
36、f test specimen onthe as-received basis. (See Guide Place the D4753) Determine the grams of air-dried sample equivalent to 10.0 g ofas-receivedair-dried equivalent specimen as obtained in 9.3 sample as follows:in the digestionequivalent sample weight,g5 (1)flask.10.0210.03percent moisture removed!/1
37、0010.2 Add 0.7 g of HgO, 15 g of powdered K2SO4, and 35 mL of H2SO4.10.3 Place the flask in an inclined position and heat gradually. Then boil briskly until the solution clears. Continue boiling foran additional 30 min.10.4 Cool, then add about 300 mL of Type III water. Cool below 25C, and then add
38、25 mL of K2S solution and mix toprecipitate the mercury.10.5 Add a pinch of zinc to prevent bumping, tilt the flask, and add a layer of NaOH solution sufficient to make the contentsstrongly alkaline. Do not agitate the mixture until the flask is connected to the digestion bulb or condenser.10.6 Plac
39、e the weighed sample in the digestion flask, add 0.7 g of HgO, 15 g of powdered K2SO4, and 35 mL of H2SO4. Placethe flask in an inclined position and heat gradually. Then boil briskly until the solution clears. Continue boiling for an additional30 min. Cool, add about 300 mL of water, cool below 25C
40、, add 25 mL of K2S solution and mix to precipitate the mercury. Adda pinch of zinc to prevent bumping, tilt the flask, and add a layer of NaOH solution sufficient to make the contents strongly alkaline.Do not agitate the mixture. Immediately connect the flask to the digestion bulb or condenser. Have
41、 the tip of the condenserimmersed in the Hboric acid (H3BO3 solution (this ) solution (the amount of boric acid need not be measured) in the receiver andthen rotate the flask to mix the contents thoroughly. Heat until the ammonia has distilled (at least 150 mL of distillate). Titrate withstandard ac
42、id using mixed indicator to violet end point.10.7 Heat until the ammonia has distilled (150 mL or more of distillate).10.8 Titrate with standard sulfuric acid using mixed indicator to violet end point. Record the amount of standard sulfuric acidused during titration to the nearest 1 mL.11. Calculati
43、on11.1 Calculate the percentage nitrogen as follows:Nitrogen as2received!,%5A 3B!30.14 (2)where:A = millilitres of 0.1 to 0.3 N H2SO4 required for titration of the solution, andA = millilitres of 0.1 to 0.3 N H2SO4 used for titration andB = normality of the H2SO4.D2973 16312. ReportReport: Test Data
44、 Sheet(s)/Form(s)12.1 The methodology used to specify how data are recorded on the test data sheet(s)/form(s), as given below, is covered in 1.4.12.2 Record as a minimum the following general information (data):12.2.1 Sample/Specimen identification information, such as, description and manufacturer
45、of the peat.12.2.2 Any special selection and preparation processes.12.2.3 Technician name or initials and date of testing.12.3 Report to the nearest 0.1 % the nitrogen content of the as-received sample. (See Practice Record as a minimum thefollowing test specimen data:D6026.)12.3.1 Record the moistu
46、re removed during air-drying.12.3.2 Record the mass of the air-dried equivalent specimen.12.3.3 Record the amount of standard sulfuric acid used during titration.12.3.4 Record the percent nitrogen of the as-received specimen to the nearest 0.1 %.13. Precision and Bias13.1 PrecisionDue Test data prec
47、ision is not presented due to the nature of the soil or rock materials tested by this method,it materials tested. It is either not feasible or too costly at this time to have ten or more laboratories participate in a round-robintesting program. Also, it is not feasible or too costly to produce multi
48、ple specimens that have uniform physical properties. Anyvariation observed in the data is just as likely to be due to specimen variation as to operator or laboratory testing variation.Subcommittee D18.18 welcomes proposals that would allow for development of a valid precision statement.13.1.1 Subcom
49、mittee D18.22 is seeking any data from the users of this test method that might be used to make a limitedstatement on precision.13.2 BiasThere is no accepted reference value for this test method, therefore, bias cannot be determined.14. Keywords14.1 chemical analysis; nitrogen compounds; peatSUMMARY OF CHANGESIn accordance with Committee D18 has identified policy, this section identifies the location of selected changesto this test method standard since the last issue,edition D297371(2004),(20101) that may impact the use of thistest me
