ASTM D888-2018 Standard Test Methods for Dissolved Oxygen in Water.pdf

《ASTM D888-2018 Standard Test Methods for Dissolved Oxygen in Water.pdf》由会员分享，可在线阅读，更多相关《ASTM D888-2018 Standard Test Methods for Dissolved Oxygen in Water.pdf（16页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D888 121D888 18Standard Test Methods forDissolved Oxygen in Water1This standard is issued under the fixed designation D888; 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 parenth

2、eses 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 U.S. Department of Defense.1 NOTETable X2.1 was corrected and the Summary of Changes was added editoriall

3、y in July 2013.1. Scope*1.1 These test methods cover the determination of dissolved oxygen in water. Three test methods are given as follows:Range, mg/L SectionsTest Method ATitrimetric ProcedureHigh Level1.0 8 to 15Test Method ATitrimetric ProcedureHighLevel1.0 8 15Test Method BInstrumental Probe P

4、rocedureElectrochemical0.05 to 20 16 to 25Test Method BInstrumental Probe ProcedureElectrochemical 0.05 to 20 16 25Test Method CInstrumental Probe ProcedureLuminescence-Based Sensor0.05 to 20 26 to 29Test Method CInstrumental Probe ProcedureLuminescence-BasedSensor0.05 to 20 26 311.2 The precision o

5、f Test Methods A and B was carried out using a saturated sample of reagent water. It is the usersresponsibility to ensure the validity of the test methods for waters of untested matrices.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in t

6、his standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory

7、limitations prior to use. For a specific precautionary statement,statements, see 7.1 and Note 17.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Sta

8、ndards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of

9、 Precision and Bias of Applicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water AnalysisE200 Practice for Preparation, Standardization, and Storage of Standard

10、 and Reagent Solutions for Chemical Analysis3. Terminology3.1 DefinitionsDefinitions: For definitions of terms used in these test methods, refer to Terminology D1129.3.1.1 For definitions of terms used in this standard, refer to Terminology D1129.1 These test methods are under the jurisdiction of AS

11、TM Committee D19 on Water and are the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved March 1, 2012May 1, 2018. Published March 2012May 2018. Originally approved in 1946. Last previous edition approved in 20092012 asD888 09.D888 121. DOI: 10.15

12、20/D0888-12E01.10.1520/D0888-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM

13、standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all

14、cases only the current versionof the standard as published by ASTM is to be considered the official document.*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. United States13.2 Definiti

15、ons of Terms Specific to This Standard:3.2.1 amperometric systems, nthose instrumental probes that involve the generation of an electrical current from which thefinal measurement is derived.3.2.2 instrumental probes, ndevices used to penetrate and examine a system for the purpose of relaying informa

16、tion on itsproperties or composition.3.2.2.1 DiscussionThe term probe is used in these test methods to signify the entire sensor assembly, including electrodes, electrolyte, membrane,materials of fabrications, and so on.3.2.3 potentiometric systems, nthose instrumental probes in which an electrical

17、potential is generated and from which the finalmeasurement is derived.4. Significance and Use4.1 Dissolved oxygen is required for the survival and growth of many aquatic organisms, including fish. The concentration ofdissolved oxygen may also be associated with corrosivity and photosynthetic activit

18、y.The absence of oxygen may permit anaerobicdecay of organic matter and the production of toxic and undesirable esthetic materials in the water.5. Purity of Reagents5.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents s

19、hall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society.3 Othergrades may be used if it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening theaccuracy of the determination.5.1.1 Reagent grade ch

20、emicals, as defined in Practice E200, shall be used unless otherwise indicated. It is intended that allreagents conform to this standard.5.2 Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to SpecificationD1193, Type I. Other reagent water types ma

21、y be used provided it is first ascertained that the water is of sufficiently high purityto permit its use without adversely affecting the bias and precision of the test method. Type II water was specified at the time ofround robin testing of this test method.6. Sampling6.1 Collect the samples in acc

22、ordance with Practices D1066 and D3370.6.2 For higher concentration of dissolved oxygen, collect the samples in narrow mouth glass-stoppered bottles of 300-mLcapacity, taking care to prevent entrainment or solution of atmospheric oxygen.6.3 With water under pressure, connect a tube of inert material

23、 to the inlet and extend the tube outlet to the bottom of the samplebottle. Use stainless steel, Type 304 or 316, or glass tubing with short neoprene connections. Do not use copper tubing, longsections of neoprene tubing, or other types of polymeric materials. The sample line shall contain a suitabl

24、e cooling coil if the waterbeing sampled is above room temperature, in which case cool the sample 16 to 18C. When a cooling coil is used, the valve forcooling water adjustment shall be at the inlet to the cooling coil, and the overflow shall be to a point of lower elevation. The valvefor adjusting t

25、he flow of sample shall be at the outlet from the cooling coil. The sample flow shall be adjusted to a rate that willfill the sampling vessel or vessels in 40 to 60 s and flow long enough to provide a minimum of ten changes of water in the samplevessel. If the sampling line is used intermittently, f

26、lush the sample line and cooling coil adequately before using.6.4 Where samples are collected at varying depths from the surface, a special sample bottle holder or weighted sampler witha removable air tight cover should be used. This unit may be designed to collect several 250 or 300 mL samples at t

27、he same time.Inlet tubes extending to the bottom of each bottle and the water after passing through the sample bottle or bottles displaces air fromthe container. When bubbles stop rising from the sampler, the unit is filled. Water temperature is measured in the excess water inthe sampler.6.5 For dep

28、ths greater than 2 m, use a Kemmerer-type sampler. Bleed the sample from the bottom of the sampler through a tubeextending to the bottom of a 250 to 300 mL biological oxygen demand (BOD) bottle. Fill the bottle to overflowing and preventturbulence and the formation of bubbles while filling the bottl

29、e.3 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharm

30、acopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D888 1827. Preservation of Samples7.1 Do not delay the determination of dissolved oxygen. Samples for Test Method A may be preserved 4 to 8 h by adding 0.7mL of concentrated sulfuric acid (sp gr 1.84) and 1.0 mL

31、 of sodium azide solution (20 g/L) to the bottle containing the samplein which dissolved oxygen is to be determined. Biological activity will be inhibited and the dissolved oxygen retained by storingat the temperature of collection or by water sealing (inverting bottle in water) and maintaining at a

32、 temperature of 10 to 20C.Complete the determination as soon as possible, using the appropriate procedure for determining the concentration of dissolvedoxygen. (WarningSodium azide is highly toxic and multagenic. Follow manufacturers instruction for handling and storage.)TEST METHOD ATITRIMETRIC PRO

33、CEDUREHIGH LEVEL8. Scope8.1 This test method is applicable to waters containing more than 1000 g/L of dissolved oxygen such as stream and sewagesamples. It is the users responsibility to ensure the validity of the test method for waters of untested matrices.8.2 This test method, with the appropriate

34、 agent, is usable with a wide variety of interferences. It is a combination of theWinklerMethod, the Alsterberg (Azide) Procedure, the Rideal-Stewart (permanganate) modification, and the Pomeroy-Kirshman-Alsterberg modification.8.3 The precision of the test method was carried out using a saturated s

35、ample of reagent water.8. Scope8.1 This test method is applicable to waters containing more than 1000 g/L of dissolved oxygen such as stream and sewagesamples. It is the users responsibility to ensure the validity of the test method for waters of untested matrices.8.2 This test method, with the appr

36、opriate agent, is usable with a wide variety of interferences. It is a combination of theWinklerMethod, the Alsterberg (Azide) Procedure, the Rideal-Stewart (permanganate) modification, and the Pomeroy-Kirshman-Alsterberg modification.8.3 The precision of the test method was carried out using a satu

37、rated sample of reagent water.9. Interferences9.1 Nitrite interferences are eliminated by routine use of sodium azide. Ferric iron interferes unless 1 mL of potassium fluoridesolution is used, in which case 100 to 200 mg/L can be tolerated. Ferrous iron interferes, but that interference is eliminate

38、d by theuse of potassium permanganate solution. High levels of organic material or dissolved oxygen can be accommodated by use of theconcentrated iodide-azide solution.10. Apparatus10.1 Sample Bottles, 250 or 300 mL capacity with tapered ground-glass stoppers. Special bottles with pointed stoppers a

39、ndflared mouths are available from supply houses, but regular types (tall or low form) are satisfactory.10.2 Pipettes, 10-mL capacity, graduated in 0.1-mL divisions for adding all reagents except sulfuric acid. These pipettes shouldhave elongated tips of approximately 10 mm for adding reagents well

40、below the surface in the sample bottle. Only the sulfuric acidused in the final step is allowed to run down the neck of the bottle into the sample.11. Reagents11.1 Alkaline Iodide Solutions:11.1.1 Alkaline Iodide SolutionDissolve 500 g of sodium hydroxide or 700 g of potassium hydroxide and 135 g of

41、 sodiumiodide or 150 g of potassium iodide (KI) in water and dilute to 1 L. Chemically equivalent potassium and sodium salts may beused interchangeably. The solution should not give a color with starch indicator when diluted and acidified. Store the solution ina dark rubber-stoppered bottle. This so

42、lution may be used if nitrite is known to be absent and must be used if adjustments are madefor ferrous ion interference.11.1.2 Alkaline Iodide-Sodium Azide Solution IThis solution may be used in all of these submethods except when adjustmentis made for ferrous ion. Dissolve 500 g of sodium hydroxid

43、e or 700 g of potassium hydroxide and 135 g of sodium iodide or 150g of potassium iodide in water and dilute to 950 mL. To the cooled solution add 10 g of sodium azide dissolved in 40 mL of water.Add the NaN3 solution slowly with constant stirring. Chemically equivalent potassium and sodium salts ma

44、y be usedinterchangeably. The solution should not give a color with starch indicator solution when diluted and acidified. Store the solutionin a dark rubber-stoppered bottle. (See 7.1.)11.1.3 Alkaline Iodide-Sodium Azide Solution IIThis solution is useful when high concentrations of organic matter a

45、re foundor when the dissolved oxygen concentration exceeds 15 mg/L. Dissolve 400 g of sodium hydroxide in 500 mL of freshly boiledand cooled water. Cool the water slightly and dissolve 900 g of sodium iodide. Dissolve 10 g of sodium azide in 40 mL of water.Slowly add, with stirring, the azide soluti

46、on to the alkaline iodide solution, bringing the total volume to 1 L. (See 7.1.)D888 18311.2 Manganous Sulfate SolutionDissolve 364 g of manganous sulfate in water, filter, and dilute to 1 L. No more than a traceof iodine should be liberated when the solution is added to an acidified potassium iodid

47、e solution.11.3 Potassium Biiodate Solution (0.025 N)Dissolve 0.8125 g of potassium biiodate in water and dilute to 1 Lin a volumetricflask.NOTE 1If the bottle technique is used, dissolve 1.2188 g of biiodate in water and dilute to 1 L to make 0.0375 N.11.4 Phenylarsine Oxide Solution (0.025 N)Disso

48、lve 2.6005 g of phenylarsine oxide in 110 mL of NaOH solution (12 g/L).Add 800 mL of water to the solution and bring to a pH of 9.0 by adding HCl (1 + 1). This should require about 2 mL of HCl.Continue acidification with HCl (1 + 1) until a pH of 6 to 7 is reached, as indicated by a glass-electrode

49、system. Dilute to 1 L.Add1 mL of chloroform for preservation. Standardize against potassium biiodate solution.NOTE 2Phenylarsine oxide is more stable than sodium thiosulfate. However, sodium thiosulfate may be used. The analyst should specify which titrantis used. For a stock solution (0.1 N), dissolve 24.82 g of Na2S2O35H2O in boiled and cooled water and dilute to 1 L. Preserve by adding 5 mL ofchloroform. For a dilute standard titrating solution (0.005 N) transfer 25.00 mL of 0.1 N Na2S2O3 to a 500-mL volumetric flask. Dilute to