1、Designation: D3867 16Standard Test Methods forNitrite-Nitrate in Water1This standard is issued under the fixed designation D3867; 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 in
2、dicates 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 fro
3、m 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 valid
4、ity 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. No other units of measurement areincluded in this standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated wi
5、th 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 Notes 1 and 2.2. Referenced Documents2.1 ASTM Standards:3D1129 Terminolog
6、y Relating to WaterD1141 Practice for the Preparation of Substitute OceanWaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD5810 Guide for Spiking
7、into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisD7781 Test Method for Nitrite-Nitrate in Water by NitrateReductaseE60 Practice for Analysis of Metals, Ores, and RelatedMaterials by SpectrophotometryE275 Practice for Describing
8、and Measuring Performance ofUltraviolet and Visible Spectrophotometers3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in these test standards,refer to Terminology D1129.4. Summary of Test Methods4.1 Total Oxidized Nitrogena filtered sample is passedthrough a column containing coppe
9、r-coated cadmium granulesto reduce nitrate ion 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 spectrophotometric
10、ally.4.2 Nitritethe nitrite ion originally present 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. S
11、ignificance and Use5.1 Both test methods use 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 sam
12、ples are to be analyzed. The manual testmethod is used for fewer samples or when automated instru-mentation is not available.5.3 These test methods replace Test Methods D1254 (Ni-trite) and D992 (Nitrate). The nitrite test method (Test MethodD1254) used a reagent that is considered to be a potential
13、carcinogen. The nitrate test method (Test Method D992) has1These 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 June 1, 2016. Published June 2016. Originallyapproved in
14、 1979. Last previous edition approved in 2009 as D3867 09. DOI:10.1520/D3867-16.2Methods 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
15、Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohock
16、en, PA 19428-2959. United States1been shown to have relatively large errors when used inwastewaters and also has greater manipulative difficulties thanthe test method described herein.5.4 Test Method D7781 uses a nitrate reductase enzyme forthe reduction of nitrate to nitrite. Cadmium is considered
17、atoxic metal. Also, the heterogeneous cadmium reductant cre-ates greater difficulty than the reduction described in this testmethod.6. Interferences6.1 Turbid samples must be filtered prior to analysis toeliminate particulate interference. Furthermore, sample turbid-ity results in a buildup on the r
18、eduction 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 i
19、n the sample 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 (SP
20、E) filter.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 c
21、hlorine will 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 sam
22、ples (Guide D5810).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
23、 indicated, 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
24、permit its 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 D1193, Type I. Other reagent water types maybe used, provided it is first ascertained that the wate
25、r is ofsufficiently 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 D3370.8
26、.2 When 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 aref
27、requently 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 additio
28、n torefrigeration 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 prescri
29、bed use 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. Sc
30、ope9.1 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
31、,the precision 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 meth
32、od for 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.4Reagent
33、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, U.K., and the United States Pharmacopeiaand Nat
34、ional 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 ofinfringement of patent or assume such liability.D3867 16210.1.5 Digital Pri
35、nter (Optional).10.1.6 Continuous Filter (Optional).10.2 Reduction ColumnsChoose the appropriate reductioncolumn for the manifold system. A schematic drawing of themanifold system is shown in Fig. 1 and the cartridge system isshown in Fig. 2.10.2.1 Reduction Column, a glass tube 8 by 50 mm with thee
36、nds reduced 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. Reagents and Materials11.1 Ammonium
37、 Chloride Solution (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 ReagentAdd the following to 800 mLof water,while stirring constantly: 100 mL of concentrated phosphoricacid (H3PO4), 10 g of su
38、lfanilamide, and 0.5 g of N-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 ofcop
39、per sulfate pentahydrate (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 o
40、ven at 105C for 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. T
41、his solution is 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
42、 in a dark bottle. 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
43、6.072 g. Add 50 mL of water to thebeaker, stir until dissolved, and transfer quantitatively to a6A 30 % aqueous solution of Brij 35, a polyoxyethylene compound withdodecyl alcohol (sp gr 1.18 to 1.22) has been found satisfactory for this purpose.7Different sizes of granulated cadmium may be used. Th
44、e analyst should ensurethat adequate reduction occurs with the size chosen.FIG. 1 Nitrite-Nitrate ManifoldD3867 1631000-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
45、-mercially available through chemical supply vendors and maybe used.NOTE 4Potassium nitrite is easily oxidized, so use only fresh bottlesof this reagent.11.10 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;
46、 prepare fresh as needed.11.11 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 sufficien
47、t purity to use withoutadversely affecting the bias and precision of the test method.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 (
48、11.6) and rinsing with water.12.1.2 Swirl the clean cadmium in 100-mL portions 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 granul
49、es with water at least 10 times toremove all of the precipitated copper.12.2 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 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 solut
