ASTM D1426-2003 Standard Test Methods for Ammonia Nitrogen In Water《水中氨态氮的标准测试方法》.pdf

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1、Designation: D 1426 03Standard Test Methods forAmmonia Nitrogen In Water1This standard is issued under the fixed designation D 1426; 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

2、 indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 These test methods cover the determination of ammonianitrogen, exclusive

3、of organic nitrogen, in water. Two testmethods are included as follows:SectionsTest Method ADirect Nesslerization 7 to 15Test Method BIon Selective Electrode 16 to 241.2 Test Method A is used for the routine determination ofammonia in steam condensates and demineralizer effluents.1.3 Test Method B i

4、s applicable 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 th

5、e twelve 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 inAppendix X1 has been usedin the past to meet requirements for predistillation of sample

6、sbeing analyzed for ammonia.1.5 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

7、prior to use.1.6 The distillation method now appears as Appendix X1and is provided as nonmandatory information only. The auto-mated colorimetric phenate method has been discontinued.2. Referenced Documents2.1 ASTM Standards:D 1066 Practice for Sampling Steam2D 1129 Terminology Relating to Water2D 11

8、92 Guide for Equipment for Sampling Water andSteam in Closed Conduits2D 1193 Specification for Reagent Water2D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on Water2D 3370 Practices for Sampling Water2D 5810 Guide for Spiking into Aqueous Samples2D 5847

9、 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3E60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption Spectrometry4E 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near Infrared Spec

10、trophotom-eters52.2 APHA Standard:Standard Methods for the Examination of Water and WasteWater63. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, refer to Terminology D 1129.4. Significance and Use4.1 Nitrogen is a nutrient in the environment and is neces-sary to sustai

11、n 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 form associated with wat

12、er 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.7Ammonia may occur in water as a product of1These test methods are under th

13、e jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved June 10, 2003. Published July 2003. Originallyapproved in 1956. Last previous edition approved in 1998 as D 1426 98.2Annual Book of ASTM St

14、andards, Vol 11.01.3Annual Book of ASTM Standards, Vol 11.02.4Annual Book of ASTM Standards, Vol 03.05.5Annual Book of ASTM Standards, Vol 03.06.6Available from American Public Health Association,800 I St. N.W., Washing-ton, DC 20001.7Quality Criteria for Water, USEPA-440/9-76-023, July 26, 1976, pp

15、. 1624.1*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.anaerobic decomposition of nitrogen containing compounds orfrom waste streams containing ammonia.5. Purity of Re

16、agents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.8Other grades may be used, pro-

17、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 indicated, references to water shall beunderstood to mean reagent water conforming to SpecificationD 1193, Type I. In addition, this

18、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 that organic compounds which might subse-quently interfere with the ammonia determination will beremoved. Regeneration of the ion

19、-exchange materials shouldbe carried out in accordance with the instructions of themanufacturer.6. Sampling6.1 Collect the sample in accordance with Practice D 1066,Specification D 1192, and Practices D 3370, as applicable.6.2 Preserve the samples by the addition of 1 mL ofconcentrated sulfuric acid

20、 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.TEST METHOD ADIRECT NESSLERIZATION7. Scope7.1 This test method is suitable for the rapid routinedetermination of ammonia nitrogen in steam condensates a

21、nddemineralized 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, cyanates, and acetamidehydrolyze very slowly in solution

22、 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. Similarly, volatile alkaline com-pounds such as hydrazine and

23、 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 prior to Nesslerization.Residual chlorine must be remove

24、d 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 analiquot of the remaining clear filtrate by direct Nessl

25、erization.Ammonia can be lost in basic conditions. Check procedurewith a standard solution.10. Apparatus10.1 Nessler Tubes Matched Nessler tubes6about 300mm long, 17-mm inside diameter, and marked for 50 mL at2256 1.5 mm from inside the bottom.10.2 PhotometerFilter photometer or spectrophotometersui

26、table for absorbance measurements at 425 nm. Filter pho-tometers and photometric practices used in this test methodshall conform to Practice E60. Spectrophotometers shallconform to Practice E 275.10.3 StoppersRubber, size No. 2, to fit Nessler tubes.These stoppers shall be boiled in H2SO4(1 + 99), r

27、insed, boiledin NaOH solution (1 g/L), rinsed, allowed to stand in diluteNessler reagent for 30 min, and then rinsed again.11. Reagents11.1 Ammonia Nitrogen Solution, Standard (1 mL = 0.01mg N)Dry reagent grade ammonium sulfate (NH4)2SO4)for1hat100C. Accurately weigh 4.718 g and dissolve inwater. Di

28、lute to 1 L in a volumetric flask. Pipet 10 mL of thisstock solution to a 1-L volumetric flask and dilute to volumewith water.11.2 Disodium Dihydrogen Ethylenediamine TetraacetateSolution (500 g/L)Dissolve 500 g of disodium dihydrogenethylenediamine tetraacetate dihydrate in water containing 100g of

29、 NaOH. Gently heat to complete dissolution. Cool anddilute to 1 L.11.3 Nessler ReagentDissolve 100 g of anhydrous mer-curic 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(Na

30、OH) in 500 mL of water. Dilute the mixture to 1 L. Storethe 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 stored in a chemically resistant bottle out ofdirect sunlight, it will remain stable up to a p

31、eriod of 1 year.NOTE 1This reagent should give the characteristic color with ammo-nia within 10 min after addition, and should not produce 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

32、(previously rinsed with reagent water Type I (see SpecificationD 1193) shortly before use.NOTE 2Mercury and its salts are hazardous materials. They should bestored, handled and dispensed accordingly. Disposal of solutions must bemade by legally acceptable means.11.4 Sodium Hydroxide Solution (240 g/

33、L)Dissolve 240 gof NaOH in water and dilute to 1 L.8Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Po

34、ole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.D 1426 03211.5 Sodium Potassium Tartrate Solution (300 g/L)Dissolve 300 g of sodium-potassium tartrate tetrahydrate in 1L of water. Boil until ammonia-free and dilut

35、e to 1 L.11.6 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 nitrogen solution diluted to 50mL with water: 0.0, 1.0, 3.0, 5.0, 8.0, an

36、d 10.0 mL. Mix, add1 mL of Nessler reagent, and remix. After 20 to 30 min, usinga photometer suitable for absorbance measurement at 425 nmand a compensatory blank (Nesslerized ammonia-free water),prepare a calibration curve based on a series of these standards.12.2 If a visual comparison method is u

37、sed, prepare a seriesof 14 Nessler tubes containing the following volumes ofstandard ammonia nitrogen solution diluted to 50 mL withwater: 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, and remix.13. Procedure13.1 If the sample contains

38、turbidity, add 1 mL of ZnSO4solution to a 100-mLaliquot and mix.Add NaOH solution withgentle mixing until the pH is about 10.5. Allow to settle andfilter using a water-washed, moderately-retentive filter paper,discarding the first 25 mL of the filtrate. Dilute a portion of thefiltrate or clear sampl

39、e, containing not more than 0.1 mg ofammonia nitrogen, to 50 mL in a Nessler tube. Add 2 drops ofsodium potassium tartrate solution (or disodium dihydrogenethylenediamine tetraacetate) to prevent cloudy tubes, and mix.Add 1 mL of Nessler solution and measure photometrically ata wavelength of 425 nm.

40、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, and remix.Compare the color developed after 10 min with the previouslyprepared standards. If the ammonia nitrogen concentration isbelo

41、w 0.008 mg (in the 50-mL tube) compare after 30 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 3 1000!/S (1)where:A = ammonia nitrogen observed, mg, andS = sample, mL.14.2 Calculate the ammonia concentrat

42、ion in mg/L of am-monia in the original sample, using Eq 2:Ammonia, mg/L 5 E 3 1.22 (2)where:E = ammonia nitrogen, mg/L.15. Precision and Bias915.1 The precision of this test method was measured with-out the use of any distillation procedure by nine laboratories inreagent water only at four levels i

43、n the range from 30 to 100mg NH3-N/L, 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 condensate or demineraliz

44、ed 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 NH3-N/L. Other precision data are shownin Table 1.15.4 Precision and bias for this test method conforms toPractice D 277777, which was in place at the

45、 time ofcollaborative testing. Under the allowances made in 1.4 of D277798, these precision and bias data do meet existingrequirements for interlaboratory studies of Committee D19 testmethods.TEST METHOD BION SELECTIVE ELECTRODE16. Scope16.1 This test method is applicable to the measurement ofammoni

46、a in reagent and effluent water.17. Summary of Test Method17.1 The sample is made alkaline with sodium hydroxide toconvert ammonium ion to ammonia. The ammonia thus formeddiffuses through a gas-permeable membrane of an ion selectiveelectrode (ISE) and alters the pH of its internal solution which,in

47、turn, is sensed by a pH electrode. The potential is measuredby means of a pH meter or an ISE meter. If the pH meter isused, the ammonia content is determined from a calibrationcurve; if the ISE meter is used, the ammonia content is readdirectly from the meter.18. Interferences18.1 Volatile amines ar

48、e positive interferences.18.2 Mercury, if present, forms ammonia complexes, thuscausing negative interference.18.3 Organic compounds that form ammonia readily (within5 min) under alkaline conditions are a positive interference. Ingeneral, this should not be a problem because the interfering9Supporti

49、ng data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D191015.TABLE 1 Determination of Precision and Bias for Test MethodADirect Nesslerization Method (Photometric at 425 nm)AmountAdded,mg/LMatrixWaterMeanRecovery,%Precision,mg/LBias,%StSo0.120 Reagent 89 0.011 0.003 10.80.200 Reagent 98 0.013 0.002 2.50.350 Reagent 98 0.021 0.002 1.71.000 Reagent 101 0.042 0.014 + 1.4D 1426 033concentrations may have to be greater than 100 mg/L. Amongthe inorganic compounds, hydrazine sulfate has yielded area