ASTM D1426-2015 Standard Test Methods for Ammonia Nitrogen In Water《水中氨态氮的标准试验方法》.pdf

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1、Designation: D1426 15Standard Test Methods forAmmonia Nitrogen In Water1This standard is issued under the fixed designation D1426; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses i

2、ndicates 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. Scope*1.1 These test methods cover the determination of ammonianitrogen, exclusiv

3、e of organic nitrogen, in water. Two testmethods are included as follows:SectionsTest Method ADirect Nesslerization 716Test Method BIon Selective Electrode 17241.2 Test Method A is used for the routine determination ofammonia in steam condensates and demineralizer effluents.1.3 Test Method B is appl

4、icable to the determination ofammonia nitrogen in the range from 0.5 to 1000 mg NH3N/Ldirectly in reagent and effluent waters. Higher concentrationscan be determined following dilution. The reported lowerrange is based on multiple-operator precision. Lower limitshave been obtained by two of the twel

5、ve laboratories partici-pating in the round robin.1.4 Both test methods A and B are applicable to surface andindustrial waters and wastewaters following distillation. Thetest method for distillation given in Appendix X1 has beenused in the past to meet requirements for predistillation ofsamples bein

6、g analyzed for ammonia.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 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 sta

7、ndard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.7 The distillation method now appears as Appendix X1and is provided as nonmandatory information only. The auto-mated colorimetric phenate method has been discontinued

8、.2. Referenced Documents2.1 ASTM Standards:2D1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Close

9、d ConduitsD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE60 Practice for Analysis of Metals, Ores, and RelatedMaterials by SpectrophotometryE275 Practice for Describing and Measuring Performance ofUltr

10、aviolet and Visible Spectrophotometers2.2 APHA Standard:3Standard Methods for the Examination of Water and WasteWater3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, refer to Terminology D1129.4. Significance and Use4.1 Nitrogen is a nutrient in the environment and is

11、 neces-sary to sustain growth of most organisms. It exists in severalforms such as nitrate, nitrite, organic nitrogen such as proteinsor amino acids, and ammonia.4.2 Ammonia is a colorless, gaseous compound with a sharpdistinctive odor. It is highly soluble in water where it exists ina molecular for

12、m associated with water and in an ionized formas NH4+. The extent of association or ionization is dependenton the temperature and pH. It may also be toxic to aquatic life.The extent of toxicity is dependent upon species and extent ofdissociation.4Ammonia may occur in water as a product of1These test

13、 methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved March 15, 2015. Published April 2015. Originallyapproved in 1956. Last previous edition approved in 2008 as D1426 08.

14、DOI:10.1520/D1426-15.2For 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.3Available fromAmerican Public HealthAss

15、ociation, 800 I St. NW, Washington,DC 20001, http:/www.apha.org.4Quality Criteria for Water, USEPA-440/9-76-023, July 26, 1976, pp. 1624.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959

16、. United States1anaerobic decomposition of nitrogen containing compounds orfrom waste streams containing ammonia.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committe

17、e on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.5Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.5.2 Unless otherwise indic

18、ated, references to water shall beunderstood to mean reagent water conforming to SpecificationD1193, Type I. In addition, this water shall be free of ammonianitrogen. Such water is best prepared by the passage of distilledwater through an ion-exchange resin. These resins should alsobe selected so th

19、at organic compounds which might subse-quently interfere with the ammonia determination will beremoved. Regeneration of the ion-exchange materials shouldbe carried out in accordance with the instructions of themanufacturer.6. Sampling6.1 Collect the sample in accordance with Practices D1066and D3370

20、, as applicable.6.2 Preserve the samples by the addition of 1 mL ofconcentrated sulfuric acid per litre and store at 4C. The pHshould be 2.0 or less. Analyze the samples within 24 h ofsampling. Do not use mercuric chloride as a preservative.NOTE 1This preservation procedure will convert cyanate to a

21、mmonia.The user must be cautioned not to acidify samples if they containcyanates. The preservation can extend the holding time to 28 days;however, the user will need to confirm the actual holding time.TEST METHOD ADIRECT NESSLERIZATION7. Scope7.1 This test method is suitable for the rapid routinedet

22、ermination of ammonia nitrogen in steam condensates anddemineralized water. See Appendix X1 for the distillation testmethod.8. Summary of Test Method8.1 A sample aliquot is Nesslerized directly and the ammo-nia content determined colorimetrically.9. Interferences9.1 Glycine, urea, glutamic acid, cya

23、nates, and acetamidehydrolyze very slowly in solution on standing, but, of these,only urea and cyanates will hydrolyze on distillation at a pH of9.5. Glycine, hydrazine, and some amines will react withNesslers reagent to give the characteristic yellow color in thetime required for the test. Similarl

24、y, volatile alkaline com-pounds such as hydrazine and the amines will influencetitrimetric results. Some organic compounds such as ketones,aldehydes, alcohols, and some amines may cause an off coloron Nesslerization. Some of these, such as formaldehyde maybe eliminated by boiling off at a low pH pri

25、or to Nesslerization.Residual chlorine must be removed prior to the ammoniadetermination by pretreatment of the sample.9.2 Turbid samples may be clarified with ZnSO4and NaOHsolution; the precipitated Zn(OH)2is filtered off, discarding thefirst 25 mL of filtrate, and the ammonia is determined on anal

26、iquot of the remaining clear filtrate by direct Nesslerization.Ammonia can be lost in basic conditions. Check procedurewith a standard solution.10. Apparatus10.1 Nessler TubesMatched Nessler tubes3about 300 mmlong, 17-mm inside diameter, and marked for 50 mL at 225 61.5 mm from inside the bottom.10.

27、2 PhotometerFilter photometer or spectrophotometersuitable for absorbance measurements at 425 nm. Filter pho-tometers and photometric practices used in this test methodshall conform to Practice E60. Spectrophotometers shall con-form to Practice E275.10.3 StoppersRubber, size No. 2, to fit Nessler tu

28、bes.These stoppers shall be boiled in H2SO4(1 + 99), rinsed,boiled in NaOH solution (1 g/L), rinsed, allowed to stand indilute Nessler reagent for 30 min, and then rinsed again.11. Reagents and Materials11.1 Ammonia Nitrogen Solution, Standard (1 mL = 0.01mg N)Dry reagent grade ammonium sulfate (NH4

29、)2SO4)for1hat100C. Accurately weigh 4.718 g and dissolve inwater. Dilute to 1 L in a volumetric flask. Pipet 10 mL of thisstock solution to a 1-L volumetric flask and dilute to volumewith water. A purchased ammonia nitrogen stock solution ofappropriate known purity is also acceptable.NOTE 2Ammonia s

30、tandards should be stored in an area free fromambient ammonia vapors.11.2 Disodium Dihydrogen Ethylenediamine TetraacetateSolution (500 g/L)Dissolve 500 g of disodium dihydrogenethylenediamine tetraacetate dihydrate in water containing 100g of NaOH. Gently heat to complete dissolution. Cool anddilut

31、e to 1 L.11.3 Filter PaperPurchase suitable filter paper. Typicallythe filter papers have a pore size of 0.45-m membrane.Material such as fine-textured, acid-washed, ashless paper, orglass fiber paper are acceptable. The user must first ascertainthat the filter paper is of sufficient purity to use w

32、ithoutadversely affecting the bias and precision of the test method.11.4 Nessler ReagentDissolve 100 g of anhydrous mercu-ric iodide (HgI2) and 70 g of anhydrous potassium iodide (KI)in a small volume of water. Add this mixture slowly, withstirring, to a cooled solution of 160 g of sodium hydroxide(

33、NaOH) in 500 mL of water. Dilute the mixture to 1 L. Store5Reagent Chemicals, American 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 L

34、td., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary,U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D1426 152the solution in the dark for five days and filter twice, eitherthrough a fritted glass crucible or glass fiber filter before using.If this reagent is s

35、tored in a chemically resistant bottle out ofdirect sunlight, it will remain stable up to a period of 1 year. Apurchased solution of appropriate known purity is also accept-able.NOTE 3This reagent should give the characteristic color with ammo-nia within 10 min after addition, and should not produce

36、 a precipitate withsmall amounts of ammonia (0.04 mg in a 50-mL volume). The solutionmay be used without 5-day storage if it is filtered through a 0.45 mmembrane (previously rinsed with reagent water Type I (see SpecificationD1193) shortly before use.NOTE 4Mercury and its salts are hazardous materia

37、ls. They should bestored, handled and dispensed accordingly. Disposal of solutions must bemade by legally acceptable means.11.5 Sodium Hydroxide Solution (240 g/L)Dissolve 240 gof NaOH in water and dilute to 1 L.11.6 Sodium Potassium Tartrate Solution (300 g/L)Dissolve 300 g of sodium-potassium tart

38、rate tetrahydrate in 1L of water. Boil until ammonia-free and dilute to 1 L.11.7 Zinc Sulfate Solution (100 g/L)Dissolve 100 g ofzinc sulfate heptahydrate (ZnSO47H2O) in water and dilute to1L.12. Calibration12.1 Prepare a series of standards containing the followingvolumes of standard ammonia nitrog

39、en solution diluted to 50mL with water: 0.0, 1.0, 3.0, 5.0, 8.0, and 10.0 mL. Mix, add1 mL of Nessler reagent (11.4), and remix. After 20 to 30 min,using a photometer suitable for absorbance measurement at425 nm and a compensatory blank (Nesslerized ammonia-freewater), prepare a calibration curve ba

40、sed on a series of thesestandards. Analyze at least three working standards containingconcentrations of ammonia nitrogen that bracket the expectedsample concentration prior to analysis of samples to calibratethe instrument.12.2 If a visual comparison method is used, prepare a seriesof 14 Nessler tub

41、es containing the following volumes ofstandard ammonia nitrogen solution (11.1) diluted to 50 mLwith water: 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.7, 2.0, 2.5, 3.0,3.5, and 4.0 mL. Mix, add 1 mL of Nessler reagent (11.4), andremix.13. Procedure13.1 If the sample contains turbidity, add 1 mL of Zn

42、SO4solution (11.7) to a 100-mL aliquot and mix. Add NaOHsolution (11.5) with gentle mixing until the pH is about 10.5.Allow to settle and filter (11.3) using a water-washed,moderately-retentive filter paper, discarding the first 25 mL ofthe filtrate. Dilute a portion of the filtrate or clear sample,

43、containing not more than 0.1 mg of ammonia nitrogen, to 50mL in a Nessler tube.Add 2 drops of sodium potassium tartratesolution (11.6) (or disodium dihydrogen ethylenediamine tet-raacetate 11.2) to prevent cloudy tubes, and mix. Add 1 mLof Nessler solution (11.4) and measure photometrically at awave

44、length of 425 nm.13.2 If a visual comparison method is used, select a volumecontaining not more than 0.04 mg of ammonia nitrogen anddilute to 50 mL. Mix, add 1 mL of Nessler reagent (11.4), andremix. Compare the color developed after 10 min with thepreviously prepared standards. If the ammonia nitro

45、gen con-centration is below 0.008 mg (in the 50-mLtube) compare after30 min.14. Calculation14.1 Calculate the ammonia concentration in mg/L of nitro-gen in the original sample, using Eq 1:Ammonia nitrogen, mg/L 5 A 31000!/S# (1)where:A = ammonia nitrogen observed, mg, andS = sample, mL.14.2 Calculat

46、e the ammonia concentration in mg/L of am-monia in the original sample, using Eq 2:Ammonia, mg/L 5 E 31.22 (2)where:E = ammonia nitrogen, mg/L.15. Precision and Bias615.1 The precision of this test method was measured with-out the use of any distillation procedure by nine laboratories inreagent wate

47、r only at four levels in the range from 30 to 100mg/L NH3-N, and each concentration was done in triplicate.The test method was tested in reagent water because steamcondensates and demineralized effluents are similar to reagentwater.15.2 Analysts using Test Method A in any matrix other thana steam co

48、ndensate or demineralized effluent must show theapplicability of this test method to that matrix.15.3 The precision of Test Method A in reagent water was0.04 mg/L at 1.0 mg/L NH3-N. Other precision data are shownin Table 1.15.4 Precision and bias for this test method conforms toPractice D2777 77, wh

49、ich was in place at the time ofcollaborative testing. Under the allowances made in 1.4 ofD2777 13, these precision and bias data do meet existingrequirements for interlaboratory studies of Committee D19 testmethods.6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D19-1015. ContactASTM CustomerService at serviceastm.org.TABLE 1 Determination of Precision and Bias for Test MethodADirect Nesslerization Method (Photometric at 425 nm)AmountAdded,mg/LMatrixWaterMeanRecovery,%Pre