ASTM D888-2012 Standard Test Methods for Dissolved Oxygen in Water《水中溶解氧的标准试验方法》.pdf

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1、Designation:D88809 Designation: D888 12Standard 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

2、 in parentheses 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. Scope *1.1 These test methods cover the determination of dissolved ox

3、ygen in water. Three test methods are given as follows:Range, mg/L SectionsTest Method ATitrimetric ProcedureHigh Level1.0 8 to 15Test Method BInstrumental Probe ProcedureElectrochemical0.05 to 20 16 to 25Test Method CInstrumental Probe ProcedureLuminescence-Based Sensor0.05 to 20 26 to 291.2 The pr

4、ecision of 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 incl

5、uded in this 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 and health practices and determine the applicability of regulatorylimitations prior to

6、 use. For a specific precautionary statement, see Note 17.2. Referenced Documents2.1 ASTM Standards:2D1066 Practice for Sampling SteamD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee

7、 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 and Reagent Solutions for Chemical Analysis3. Terminology3

8、.1 DefinitionsFor definitions of terms used in these test methods, refer to Terminology D1129.3.2 Definitions 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.

9、2 instrumental probes, ndevices used to penetrate and examine a system for the purpose of relaying information 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 o

10、f fabrications, etc. and so on.3.2.3 potentiometric systems, nthose instrumental probes in which an electrical 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, includin

11、g fish. The concentration of1These test methods are under the jurisdiction of ASTM Committee D19 on Water and are the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved Nov.March 1, 2009.2012. Published December 2009.March 2012. Originally approve

12、d in 1946. Last previous edition approved in 20052009 asD888 059. DOI: 10.1520/D0888-09.10.1520/D0888-12.2For 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

13、 Document Summary page on the ASTM website.1This document is not an ASTM 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,

14、ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.diss

15、olved oxygen may also be associated with corrosivity and photosynthetic activity.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 u

16、sed in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society.3Othergrades may be used if it is first ascertained that the reagent is of sufficiently high purity to permit its

17、 use without lessening theaccuracy of the determination.5.1.1 Reagent grade chemicals, 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 reagen

18、t water conforming to SpecificationD1193, Type I. Other reagent water types may 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 ofrou

19、nd robin testing of this method.6. Sampling6.1 Collect the samples in accordance 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 atmospher

20、ic oxygen.6.3 With water under pressure, connect a tube of inert material 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 ot

21、her types of polymeric materials. The sample line shall contain a suitable 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

22、overflow shall be to a point of lower elevation. The valvefor adjusting the 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

23、water in the samplevessel. If the sampling line is used intermittently, flush 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

24、. This unit may be designed to collect several 250 or 300 mL samples at the 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. Wa

25、ter temperature is measured in the excess water inthe sampler.6.5 For depths 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 a

26、nd preventturbulence and the formation of bubbles while filling the bottle.7. Preservation of Samples7.1 Do not delay the determination of dissolved oxygen. Samples for Test Method A may be preserved 4 to8hbyadding 0.7mL of concentrated sulfuric acid (sp gr 1.84) and 1.0 mL of sodium azide solution

27、(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 temperature of 10 to 20C.

28、Complete the determination as soon as possible, using the appropriate procedure for determining the concentration of dissolvedoxygen.TEST METHOD ATITRIMETRIC PROCEDUREHIGH LEVEL8. Scope8.1 This test method is applicable to waters containing more than 1000 g/L of dissolved oxygen such as stream and s

29、ewagesamples. 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 agent, is usable with a wide variety of interferences. It is a combination of theWinklerMethod, the Alsterberg (Azide) Procedure, the Ride

30、al-Stewart (permanganate) modification, and the Pomeroy-Kirshman-Alsterberg modification.8.3 The precision of the test method was carried out using a saturated sample of reagent water.3Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, Washington, DC. For sugges

31、tions 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 Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D888 1229. Interferences9.1 N

32、itrite 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 eliminated by theuse of potassium permanganate solution. Hig

33、h 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 andflared mouths are available from supply houses, b

34、ut 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 below the surface in the sample bottle. Only the su

35、lfuric 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 sodiumiodide or 150 g of potassium iodide (KI) in

36、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 solution may be used if nitrite is known to be absent

37、 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 hydroxide or 700 g of potassium hydroxide and 135 g of sodi

38、um 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 NaN3solution slowly with constant stirring. Chemically equivalent potassium and sodium salts may be usedinterchangeably. The solution should not gi

39、ve a color with starch indicator solution when diluted and acidified. Store the solutionin a dark rubber-stoppered bottle.11.1.3 Alkaline Iodide-Sodium Azide Solution IIThis solution is useful when high concentrations of organic matter are foundor when the dissolved oxygen concentration exceeds 15 m

40、g/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 solution to the alkaline iodide solution, bringing the total volume t

41、o 1 L.11.2 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 iodide solution.11.3 Potassium Biiodate Solution (0.025 N)Dissolve 0.8125 g of potassiu

42、m 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)Dissolve 2.6005 g of phenylarsine oxide in 110 mL of NaOH solution (12 g/L).Add 800 mL

43、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 system. Dilute to 1 L.Add1 mL of chloroform for preservation. Standardize against

44、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

45、by adding 5 mL ofchloroform. For a dilute standard titrating solution (0.005 N) transfer 25.00 mL of 0.1 N Na2S2O3to a 500-mL volumetric flask. Dilute to the mark withwater and mix completely. Do not prepare more than 12 to 15 h before use.NOTE 3If the full bottle technique is used, 3.9007 g must be

46、 used to make 0.0375 N.NOTE 4If sodium thiosulfate is used, prepare and preserve a 0.1 N solution as described in Note 1. Determine the exact normality by titration against0.025 N potassium biiodate solution. Dilute the appropriate volume (nominally 250 mL) of standardized 0.1 N Na2S2O3solution to 1

47、 L. One millilitreof 0.025 N thiosulfate solution is equivalent to 0.2 mg of oxygen. If the full bottle technique is followed, use 37.5 mL of sodium thiosulfate solution andstandardize to 0.0375 N.11.5 Starch SolutionMake a paste of6gofarrowroot starch or soluble iodometric starch with cold water. P

48、our the paste into1 L of boiling water. Then add 20 g of potassium hydroxide, mix thoroughly, and allow to stand for 2 h.Add 6 mL of glacial aceticacid (99.5 %). Mix thoroughly and then add sufficient HCl (sp gr 1.19) to adjust the pH value of the solution to 4.0. Store in aglass-stoppered bottle. S

49、tarch solution prepared in this manner will remain chemically stable for one year.NOTE 5Powdered starches such as thyodene have been found adequate. Some commercial laundry starches have also been found to be usable.NOTE 6If the indicator is not prepared as specified or a proprietary starch indicator preparation is used, the report of analysis shall state this deviation.11.6 Sulfuric Acid (sp gr 1.84)Concentrated sulfuric acid. One millilitre neutralizes about 3 mLof the alkaline iodide reagent.NOTE 7Sulfamic acid (3 g) may be substituted.11.7 Pota