ASTM D1426-2008 Standard Test Methods for Ammonia Nitrogen In Water《水中氨态氮的标准试验方法》.pdf

1、Designation: D 1426 08Standard 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 () 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. Scope1.1 These test methods cover the determination of ammonianitrogen, exclusive of

3、 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 is

4、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 the

5、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 samplesb

6、eing 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

7、standard 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 discontin

8、ued.2. Referenced Documents2.1 ASTM Standards:2D 1066 Practice for Sampling SteamD 1129 Terminology Relating to WaterD 1192 Guide for Equipment for Sampling Water andSteam in Closed Conduits3D 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Te

9、st Methods of Committee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 5810 Guide for Spiking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE60 Practice for Analysis of Metals, Ores, and RelatedMateria

10、ls by Molecular Absorption SpectrometryE 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-eters2.2 APHA Standard4:Standard Methods for the Examination of Water and WasteWater3. Terminology3.1 DefinitionsFor definitions of terms used in the

11、se testmethods, refer to Terminology D 1129.4. Significance and Use4.1 Nitrogen is a nutrient in the environment and is 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 co

12、lorless, gaseous compound with a sharpdistinctive odor. It is highly soluble in water where it exists ina molecular form associated with water and in an ionized form1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 o

13、n InorganicConstituents in Water.Current edition approved Aug. 15, 2008. Published September 2008. Originallyapproved in 1956. Last previous edition approved in 2003 as D 1426 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.

14、 For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from American Public Health Association, 800 I St. N.W., Washing-ton, DC 20001, http:/www.apha.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box

15、C700, West Conshohocken, PA 19428-2959, United States.as 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.5Ammonia may occur in water as a product ofana

16、erobic 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 Committee on AnalyticalReag

17、ents of the American Chemical Society, where suchspecifications are available.6Other 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 indicated, references to

18、 water shall beunderstood to mean reagent water conforming to SpecificationD 1193, 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 that organic compoun

19、ds 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 Practice D 1066,Specification D 1192, and

20、Practices D 3370, 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.TEST METHOD ADIRECT NESSLERIZATION7. Scope7

21、.1 This test method is suitable for the rapid routinedetermination 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 colorimetrical

22、ly.9. Interferences9.1 Glycine, urea, glutamic acid, cyanates, 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

23、 yellow color in thetime required for the test. Similarly, 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 form

24、aldehyde maybe eliminated by boiling off at a low pH prior 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、25 mL of filtrate, and the ammonia is determined on analiquot of the remaining clear filtrate by direct Nesslerization.Ammonia can be lost in basic conditions. Check procedurewith a standard solution.10. Apparatus10.1 Nessler Tubes Matched Nessler tubes4about 300mm long, 17-mm inside diameter, and m

26、arked for 50 mLat 2256 1.5 mm from inside the bottom.10.2 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 shallconform to Practice E

27、 275.10.3 StoppersRubber, size No. 2, to fit Nessler tubes.These stoppers shall be boiled in H2SO4(1 + 99), rinsed, 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

28、N)Dry reagent grade ammonium sulfate (NH4)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.11.2 Disodium Dihydrogen Ethylenediamine TetraacetateSolution (50

29、0 g/L)Dissolve 500 g of disodium dihydrogenethylenediamine tetraacetate dihydrate in water containing 100g of 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

30、 volume of water. Add this mixture slowly, withstirring, to a cooled solution of 160 g of sodium hydroxide(NaOH) 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 t

31、his reagent is stored in a chemically resistant bottle out ofdirect sunlight, it will remain stable up to a period 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

32、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 SpecificationD 1193) shortly before use.NOTE 2Mercury and its salts are hazardous materials. They should be5Quality Criteria for Water, USEPA

33、-440/9-76-023, July 26, 1976, pp. 1624.6Reagent 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 Ltd., Poole, Dorset,

34、 U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D1426082stored, handled and dispensed accordingly. Disposal of solutions must bemade by legally acceptable means.11.4 Sodium Hydroxide Solution (240 g/L)Dissolve 240 gof NaOH in

35、water and dilute to 1 L.11.5 Sodium Potassium Tartrate Solution (300 g/L)Dissolve 300 g of sodium-potassium tartrate tetrahydrate in 1L of water. Boil until ammonia-free and dilute to 1 L.11.6 Zinc Sulfate Solution (100 g/L)Dissolve 100 g ofzinc sulfate heptahydrate (ZnSO47H2O) in water and dilute t

36、o1L.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, and 10.0 mL. Mix, add1 mL of Nessler reagent, and remix. After 20 to 30 min, usinga photometer suitable for absorbance meas

37、urement 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 used, prepare a seriesof 14 Nessler tubes containing the following volumes ofstandard ammonia nitrogen solution diluted to

38、 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 turbidity, add 1 mL of ZnSO4solution to a 100-mLaliquot and mix.Add NaOH solution withgentle mixing until the pH is about

39、 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 sample, containing not more than 0.1 mg ofammonia nitrogen, to 50 mL in a Nessler tube. Add 2 drops ofsodium potassium tartrat

40、e 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.13.2 If a visual comparison method is used, select a volumecontaining not more than 0.04 mg of ammonia nitrogen anddilute

41、 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 isbelow 0.008 mg (in the 50-mL tube) compare after 30 min.14. Calculation14.1 Calculate the ammonia concentration in mg/L of ni

42、tro-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 concentration 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.1

43、5. Precision and Bias715.1 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 in the range from 30 to 100mg NH3-N/L, and each concentration was done in triplicate.The test method was tested in reagent

44、 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 demineralized effluent must show theapplicability of this test method to that matrix.15.3 The precision of Test Method A in reagent

45、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 time ofcollaborative testing. Under the allowances made in 1.4 ofD 277706, these precision and bias data do meet existin

46、grequirements for interlaboratory studies of Committee D19 testmethods.TEST METHOD BION SELECTIVE ELECTRODE16. Scope16.1 This test method is applicable to the measurement ofammonia in reagent and effluent water.17. Summary of Test Method17.1 The sample is made alkaline with sodium hydroxide toconver

47、t 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 turn, is sensed by a pH electrode. The potential is measuredby means of a pH meter or an ISE meter. If the pH meter isuse

48、d, 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 are positive interferences.18.2 Mercury, if present, forms ammonia complexes, thuscausing negative interference.7Supporting

49、 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 + 1.4D142608318.3 Organic compounds that form ammonia readily (within5 min) under alkaline conditions are a positive interference.