ASTM D3867-2009 Standard Test Methods for Nitrite-Nitrate in Water《水中亚硝酸盐-硝酸盐的标准试验方法》.pdf

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1、Designation: D 3867 09Standard Test Methods forNitrite-Nitrate in Water1This standard is issued under the fixed designation D 3867; 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.1. Scope*1.1 These test methods cover the determination of nitritenitrogen, nitrate nitrogen, and combined nitrite-nitrate nitrogenin water and wastewater in the range f

3、rom 0.05 to 1.0 mg/Lnitrogen. Two test methods2are given as follows:SectionsTest Method AAutomated Cadmium Reduction 9 to 18Test Method BManual Cadmium Reduction 19 to 281.2 These test methods are applicable to surface, saline,waste, and ground waters. It is the users responsibility toensure the val

4、idity of these test methods for waters of untestedmatrices.1.3 The values stated in either SI or inch-pound units are tobe regarded as the standard. The values given in parenthesesare for information only.1.4 This standard does not purport to address all of thesafety concerns, if any, associated wit

5、h 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 prior to use. For specific hazardstatements, see Note 1 and Note 2.2. Referenced Documents2.1 ASTM Standards:3D 1129 Termin

6、ology Relating to WaterD 1141 Practice for the Preparation of Substitute OceanWaterD 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 5810 Guide for

7、 Spiking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 275 Practice for Describing and Measuring Performanceof Ultraviolet

8、 and Visible Spectrophotometers3. Terminology3.1 Definitions: For definitions of terms used in these testmethods, refer to Terminology D 1129.4. Summary of Test Methods4.1 Total Oxidized Nitrogena filtered sample is passedthrough a column containing copper-coated cadmium granulesto reduce nitrate io

9、n to nitrite ion. The combined nitrite-nitratenitrogen is determined by diazotizing the total nitrite ion withsulfanilamide and coupling with N-(1-naphthyl)ethylenediamine dihydrochloride to form a highlycolored azo dye that is measured spectrophotometrically.4.2 Nitritethe nitrite ion originally pr

10、esent in the samplecan be determined separately by carrying out the procedure andomitting the cadmium reduction step.4.3 Nitratethe nitrate ion can be calculated as the differ-ence between the combined nitrite-nitrate nitrogen and thenitrite nitrogen.5. Significance and Use5.1 Both test methods use

11、identical reagents and sampleprocessing. The only difference between the two methods isthat one test method is automated and the other is manual. Theranges and interferences are identical.5.2 The automated test method is preferred when largenumbers of samples are to be analyzed. The manual testmetho

12、d is used for fewer samples or when automated instru-mentation is not available.1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved May 15, 2009. Published May 2009.

13、Originallyapproved in 1979. Last previous edition approved in 2004 as D 3867 04.2Methods similar to these appear in Methods of Chemical Analysis of Water andWastes, 2nd edition, U.S. Environmental Protection Agency.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM

14、Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoho

15、cken, PA 19428-2959, United States.5.3 These test methods replace Test Methods D 1254 (Ni-trite) and D 992 (Nitrate). The nitrite test method (Test MethodD 1254) used a reagent that is considered to be a potentialcarcinogen. The nitrate test method (Test Method D 992) hasbeen shown to have relativel

16、y large errors when used inwastewaters and also has greater manipulative difficulties thanthe test method described herein.6. Interferences6.1 Turbid samples must be filtered prior to analysis toeliminate particulate interference. Furthermore, sample turbid-ity results in a buildup on the reduction

17、column that restrictssample flow.6.2 Sample color that absorbs at wavelengths between 520and 540 nm interferes with the absorbance measurements.When color is suspect, analyze a sample blank, omitting theN-(1-naphthyl)ethylenediamine dihydrochloride from the colorreagent.6.3 Oil and grease in the sam

18、ple coat the surface of thecadmium and prevent complete reduction of nitrate to nitrite.This interference is usually removed by filtration prior toanalysis. If filtration is not adequate, the interference can beremoved by extracting the sample with an n-hexane or a solidphase extraction (SPE) filter

19、.6.4 Certain metal ions, in concentrations above 35 mg/L,may cause interferences. For example, Hg (II) and Cu (II) mayform colored complex ions having absorption bands in theregion of color measurement. Iron and manganese are otherreported examples of interference.6.5 Excessive amounts of chlorine w

20、ill deactivate the reduc-ing column. Chlorine might be present in some Type II water.The use of chlorine-containing Type II water will lead to anegative interference because nitrite and chlorine do notnormally coexist. This is of particular importance when pre-paring standards or spiked samples (Gui

21、de D 5810).6.6 In acid samples (pH less than 4.5) nitrate is not reducedin the cadmium column. To overcome this interference, thesample must be neutralized to a pH of between 6 and 8 prior toanalysis.7. Purity of Reagents7.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicat

22、ed, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, when suchspecifications are available.4Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficient highpurity to permit i

23、ts use without lessening the accuracy of thedetermination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type I. Other reagent water types maybe used, provided it is first ascertained that the water is of

24、sufficiently high purity to permit its use without adverselyaffecting the bias and precision of these test methods. Type IIwater was specified at the time of round-robin testing of thesetest methods.8. Sampling and Sample Preservation8.1 Collect the sample in accordance with Practices D 3370.8.2 Whe

25、n nitrite ion is to be determined separately, analyzeas soon as possible after sampling. Even when sterile bottlesare used, bacteria naturally present in the water may causeconversion of all or part of nitrite ion to other forms such asnitrate or ammonia. Ammonia and natural amines, which arefrequen

26、tly present in natural waters, may react with nitrites toform nitrogen. If samples are to be stored for 24 h or less,preserve the sample by refrigeration at 4C. If the sample mustbe stored for more than 24 h, preserve it by the addition of 2mL of chloroform per litre (11.7 and 11.9) in addition tore

27、frigeration at 4C.NOTE 1WARNING: Chloroform is toxic and is a suspected humancarcinogen. Use with adequate ventilation or in a fume hood. Wearprescribed protective equipment. Use of chloroform is discouraged, sinceits use renders the solution a hazardous waste.NOTE 2CAUTION: The common prescribed us

28、e of sulfuric acid ormercury compounds as preservatives is discouraged. Sulfuric acid doesnot necessarily inhibit oxidation and mercury compounds should beavoided to prevent environmental pollution. Mercuric chloride is knownto deactivate the column.TEST METHOD AAUTOMATED CADMIUMREDUCTION9. Scope9.1

29、 The applicable range of this test method is from 0.05 to1 mg/L of nitrite or nitrate nitrogen. The range may beextended upward by dilution of an appropriate aliquot. Manyworkers have found that this test method is reliable for nitriteand combined nitrite-nitrate levels to 0.01 mg N/L. However,the p

30、recision and bias data presented in this test method areinsufficient to justify application of this test method in the 0.01to 0.05 mg/L-N range.9.2 This test method is applicable to surface, saline, waste,and ground waters. It is the users responsibility to ensure thevalidity of this test method for

31、 waters of untested matrices.10. Apparatus10.1 Automated Analysis System5consisting of:10.1.1 Sampler.10.1.2 Manifold or Analytical Cartridge.10.1.3 Colorimeter equipped with a 15- or 50-mm tubularflow cell and 540 6 10-nm filters.10.1.4 Recorder or Electronic Data Acquisition Device.10.1.5 Digital

32、Printer (Optional).10.1.6 Continuous Filter (Optional).4Reagent 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.

33、, Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.5The apparatus described is commercially available. ASTM does not undertaketo ensure anyone utilizing an automated analysis system against liability ofinfringemen

34、t of patent or assume such liability.D386709210.2 Reduction ColumnsChoose the appropriate reduc-tion column for the manifold system. A schematic drawing ofthe manifold system is shown in Fig. 1 and the cartridge systemis shown in Fig. 2.10.2.1 Reduction Column, a glass tube 8 by 50 mm with theends r

35、educed in diameter to permit insertion into the system(see Fig. 1).10.2.2 Reduction Column, a U-shaped glass tubing,350-mm length and 2-mm inside diameter.NOTE 3A pump tube with 0.081-in. (2.1-mm) inside diameter can beused in place of the 2-mm glass tube.11. Reagents11.1 Ammonium Chloride Solution

36、(85 g/L)Dissolve 85 gof ammonium chloride (NH4Cl) in water and dilute to 1 L.Add0.5 mL wetting agent.611.2 Cadmium, 40 to 60 mesh, granulated.711.3 Color Reagent Add the following to 800 mL ofwater, while stirring constantly: 100 mL of concentratedphosphoric acid (H3PO4), 10 g of sulfanilamide, and

37、0.5 g ofN-1-(naphthyl)ethylenediamine dihydrochloride. Stir until dis-solved. Add 1 mL of wetting agent,6and dilute to 1 L withwater. This solution is stable for about a month when stored ina brown bottle in a dark cool place.11.4 Copper Sulfate Solution (20 g/L)Dissolve 20 g ofcopper sulfate pentah

38、ydrate (CuSO45H2O) in 500 mL ofwater. Dilute to 1 L.11.5 n-Hexane.11.6 Hydrochloric Acid (1 + 1)Slowly add 50 mL ofconcentrated hydrochloric acid (HCl) to 40 to 45 mL of waterand dilute to 100 mL.11.7 Nitrate Solution, Stock (1.0 mL = 1.0 mg NO3-N)Dry potassium nitrate (KNO3) in an oven at 105C for

39、24 h.Dissolve 7.218 g in water in a 1-L volumetric flask. Dilute tothe mark with water. This solution is stable for up to 1 monthwith refrigeration. If longer stability is required or refrigerationis not available, add 2 mL of chloroform as a preservative andstore in a dark bottle. This solution is

40、stable for 6 months. (SeeNote 1.) Alternatively, certified nitrate stock solutions arecommercially available through chemical supply vendors andmay be used.11.8 Nitrate Solution, Standard (1.0 mL = 0.01 mg NO3-N)Dilute 10 mL of stock nitrate solution (11.7) to 1 L withwater and store in a dark bottl

41、e. Prepare fresh as needed.11.9 Nitrite Solution, Stock (1.0 mL = 1.0 mg NO2-N)Place about7gofpotassium nitrite (KNO2) in a tared 125-mLbeaker and dry for about 24 h to a constant weight in adesiccator containing a suitable desiccant. Adjust the weight ofthe dry potassium nitrite to 6.072 g. Add 50

42、mL of water to thebeaker, stir until dissolved, and transfer quantitatively to a1000-mL volumetric flask. Dilute to the mark with water storein a sterilized bottle under refrigeration. Prepare fresh asneeded. Alternatively, certified nitrite stock solutions are com-mercially available through chemic

43、al supply vendors and maybe used.NOTE 4Potassium nitrite is easily oxidized, so use only fresh bottlesof this reagent.6A 30 % aqueous solution of Brijt 35, a polyoxyethylene compound withdodecyl alcohol (sp gr 1.18 to 1.22) has been found satisfactory for this purpose.7Different sizes of granulated

44、cadmium may be used. The analyst should ensurethat adequate reduction occurs with the size chosen.FIG. 1 Nitrite-Nitrate ManifoldD386709311.10 Nitrite Solution, Standard (1.0 mL = 0.01 mg NO2-N)Dilute 10 mL of stock nitrite solution (11.9) to 1 L withwater. This solution is unstable; prepare fresh a

45、s needed.12. Preparation of Reduction Column12.1 Cadmium Granules TreatmentClean and copperizenew or used cadmium granules in the following manner:12.1.1 Clean about 10 g of cadmium granules (11.2)bywashing with dilute HCl (11.6) and rinsing with water.12.1.2 Swirl the clean cadmium in 100-mL portio

46、ns ofcopper sulfate solution (11.4) in a beaker for 5 min or until theblue color partially fades. Decant and repeat with fresh coppersulfate until the first visible brown colloidal precipitate ap-pears.12.1.3 Wash the granules with water at least 10 times toremove all of the precipitated copper.12.2

47、 Filling the Reduction Column:12.2.1 Insert a small plug of glass wool in one end of thecolumn (10.2).12.2.2 Fill the column with water to prevent the entrapmentof air bubbles during the filling operation.12.2.3 Fill the column with copper-cadmium granules, tapto pack the granules, and plug the open

48、 end with glass wool.12.3 Installation of Reduction ColumnInstall the copper-cadmium reduction column in the automatic analyzer system.Purge the system with ammonium chloride solution (11.1)using water in the sample line. Observe the following precau-tions while installing the reduction column:12.3.

49、1 Place the column in the manifold system in anupflow 20 incline to minimize channeling (see Fig. 1).12.3.2 Fill all pump tubes with reagents before inserting thecolumn in the cartridge system to prevent the entrapment of airbubbles.12.4 Reduction Column StorageWhen it is not in use, putthe sample line in water and purge the column with ammoniumchloride solution (11.1) and water.NOTE 5Do not allow air to enter the column and do not let thecadmium granules become dry. If this occurs, refill the column withfreshly treated cadmium granules.13. Calibration