1、Designation: D888 121Standard 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 parentheses in
2、dicates 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.1NOTETable X2.1 was corrected and the Summary of Changes was added editorially in July 201
3、3.1. Scope*1.1 These test methods cover the determination of dissolvedoxygen in water. Three test methods are given as follows:Range, mg/L SectionsTest Method ATitrimetric ProcedureHigh Level1.0 8 to 15Test Method BInstrumental ProbeProcedureElectrochemical0.05 to 20 16 to 25Test Method CInstrumenta
4、l ProbeProcedureLuminescence-Based Sensor0.05 to 20 26 to 291.2 The precision of Test Methods A and B was carried outusing a saturated sample of reagent water. It is the usersresponsibility to ensure the validity of the test methods forwaters of untested matrices.1.3 The values stated in SI units ar
5、e to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 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 standard to establish appro-priate safety and health practices
6、 and determine the applica-bility of regulatory limitations prior to use. For a specificprecautionary 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 Determin
7、ation of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE200 Practice for Preparation, Standardization, and Storageof Sta
8、ndard and Reagent Solutions for Chemical Analysis3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 amperometric systems, nthose instrumental probesthat involve the generation of an elec
9、trical current from whichthe final measurement is derived.3.2.2 instrumental probes, ndevices used to penetrate andexamine a system for the purpose of relaying information on itsproperties or composition.3.2.2.1 DiscussionThe term probe is used in these testmethods to signify the entire sensor assem
10、bly, includingelectrodes, electrolyte, membrane, materials of fabrications,and so on.3.2.3 potentiometric systems, nthose instrumental probesin which an electrical potential is generated and from which thefinal measurement is derived.4. Significance and Use4.1 Dissolved oxygen is required for the su
11、rvival andgrowth of many aquatic organisms, including fish. The con-centration of dissolved oxygen may also be associated withcorrosivity and photosynthetic activity. The absence of oxygenmay permit anaerobic decay of organic matter and the produc-tion of toxic and undesirable esthetic materials in
12、the water.1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved March 1, 2012. Published March 2012. Originallyapproved in 1946. Last previous edition approved i
13、n 2009 as D888 09. DOI:10.1520/D0888-12E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM 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 Chan
14、ges section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Purity of Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended th
15、atall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society.3Other grades may be used if it is first ascertained that thereagent is of sufficiently high purity to permit its use withoutlessening the accuracy of the determination.5.1.1 Re
16、agent 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 beunderstood to mean reagent water conforming to SpecificationD1193, Type I. Other reagent wa
17、ter types may be usedprovided it is first ascertained that the water is of sufficientlyhigh purity to permit its use without adversely affecting thebias and precision of the test method. Type II water wasspecified at the time of round robin testing of this test method.6. Sampling6.1 Collect the samp
18、les in accordance with Practices D1066and D3370.6.2 For higher concentration of dissolved oxygen, collectthe samples in narrow mouth glass-stoppered bottles of300-mL capacity, taking care to prevent entrainment or solu-tion of atmospheric oxygen.6.3 With water under pressure, connect a tube of inert
19、material to the inlet and extend the tube outlet to the bottom ofthe sample bottle. Use stainless steel, Type 304 or 316, or glasstubing with short neoprene connections. Do not use coppertubing, long sections of neoprene tubing, or other types ofpolymeric materials. The sample line shall contain a s
20、uitablecooling coil if the water being sampled is above roomtemperature, in which case cool the sample 16 to 18C. Whena cooling coil is used, the valve for cooling water adjustmentshall be at the inlet to the cooling coil, and the overflow shallbe to a point of lower elevation. The valve for adjusti
21、ng theflow of sample shall be at the outlet from the cooling coil. Thesample flow shall be adjusted to a rate that will fill the samplingvessel or vessels in 40 to 60 s and flow long enough to providea minimum of ten changes of water in the sample vessel. If thesampling line is used intermittently,
22、flush the sample line andcooling coil adequately before using.6.4 Where samples are collected at varying depths from thesurface, a special sample bottle holder or weighted samplerwith a removable air tight cover should be used. This unit maybe designed to collect several 250 or 300 mL samples at the
23、same time. Inlet tubes extending to the bottom of each bottleand the water after passing through the sample bottle or bottlesdisplaces air from the container. When bubbles stop rising fromthe sampler, the unit is filled. Water temperature is measured inthe excess water in the sampler.6.5 For depths
24、greater than 2 m, use a Kemmerer-typesampler. Bleed the sample from the bottom of the samplerthrough a tube extending to the bottom of a 250 to 300 mLbiological oxygen demand (BOD) bottle. Fill the bottle tooverflowing and prevent turbulence and the formation ofbubbles while filling the bottle.7. Pr
25、eservation of Samples7.1 Do not delay the determination of dissolved oxygen.Samples for Test Method A may be preserved 4 to8hbyadding 0.7 mL of concentrated sulfuric acid (sp gr 1.84) and1.0 mL of sodium azide solution (20 g/L) to the bottlecontaining the sample in which dissolved oxygen is to bedet
26、ermined. Biological activity will be inhibited and thedissolved oxygen retained by storing at the temperature ofcollection or by water sealing (inverting bottle in water) andmaintaining at a temperature of 10 to 20C. Complete thedetermination as soon as possible, using the appropriateprocedure for d
27、etermining the concentration of dissolvedoxygen.TEST METHOD ATITRIMETRIC PROCEDUREHIGH LEVEL8. Scope8.1 This test method is applicable to waters containing morethan 1000 g/Lof dissolved oxygen such as stream and sewagesamples. It is the users responsibility to ensure the validity ofthe test method f
28、or waters of untested matrices.8.2 This test method, with the appropriate agent, is usablewith a wide variety of interferences. It is a combination of theWinkler Method, theAlsterberg (Azide) Procedure, the Rideal-Stewart (permanganate) modification, and the Pomeroy-Kirshman-Alsterberg modification.
29、8.3 The precision of the test method was carried out using asaturated sample of reagent water.9. Interferences9.1 Nitrite interferences are eliminated by routine use ofsodium azide. Ferric iron interferes unless 1 mL of potassiumfluoride solution is used, in which case 100 to 200 mg/L can betolerate
30、d. Ferrous iron interferes, but that interference iseliminated by the use of potassium permanganate solution.High levels of organic material or dissolved oxygen can beaccommodated by use of the concentrated iodide-azide solu-tion.10. Apparatus10.1 Sample Bottles, 250 or 300 mL capacity with taperedg
31、round-glass stoppers. Special bottles with pointed stoppersand flared mouths are available from supply houses, but regulartypes (tall or low form) are satisfactory.10.2 Pipettes, 10-mL capacity, graduated in 0.1-mL divi-sions for adding all reagents except sulfuric acid. Thesepipettes should have el
32、ongated tips of approximately 10 mm3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K
33、., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D888 1212for adding reagents well below the surface in the sample bottle.Only the sulfuric acid used in the final step is allowed to rundown the neck of the bottle into the sample.11
34、. Reagents11.1 Alkaline Iodide Solutions:11.1.1 Alkaline Iodide SolutionDissolve 500 g of sodiumhydroxide or 700 g of potassium hydroxide and 135 g ofsodium iodide or 150 g of potassium iodide (KI) in water anddilute to 1 L. Chemically equivalent potassium and sodiumsalts may be used interchangeably
35、. The solution should notgive a color with starch indicator when diluted and acidified.Store the solution in a dark rubber-stoppered bottle. Thissolution may be used if nitrite is known to be absent and mustbe used if adjustments are made for ferrous ion interference.11.1.2 Alkaline Iodide-Sodium Az
36、ide Solution IThis solu-tion may be used in all of these submethods except whenadjustment is made for ferrous ion. Dissolve 500 g of sodiumhydroxide or 700 g of potassium hydroxide and 135 g ofsodium iodide or 150 g of potassium iodide in water and diluteto 950 mL. To the cooled solution add 10 g of
37、 sodium azidedissolved in 40 mL of water. Add the NaN3solution slowlywith constant stirring. Chemically equivalent potassium andsodium salts may be used interchangeably. The solution shouldnot give a color with starch indicator solution when diluted andacidified. Store the solution in a dark rubber-
38、stoppered bottle.11.1.3 Alkaline Iodide-Sodium Azide Solution IIThis so-lution is useful when high concentrations of organic matter arefound or when the dissolved oxygen concentration exceeds 15mg/L. Dissolve 400 g of sodium hydroxide in 500 mL offreshly boiled and cooled water. Cool the water sligh
39、tly anddissolve 900 g of sodium iodide. Dissolve 10 g of sodium azidein 40 mL of water. Slowly add, with stirring, the azide solutionto the alkaline iodide solution, bringing the total volume to 1 L.11.2 Manganous Sulfate SolutionDissolve 364 g of man-ganous sulfate in water, filter, and dilute to 1
40、 L. No more thana trace of iodine should be liberated when the solution is addedto an acidified potassium iodide solution.11.3 Potassium Biiodate Solution (0.025 N)Dissolve0.8125 g of potassium biiodate in water and dilute to 1 L in avolumetric flask.NOTE 1If the bottle technique is used, dissolve 1
41、.2188 g of biiodatein water and dilute to 1 L to make 0.0375 N.11.4 Phenylarsine Oxide Solution (0.025 N)Dissolve2.6005 g of phenylarsine oxide in 110 mL of NaOH solution(12 g/L). Add 800 mL of water to the solution and bring to apH of 9.0 by adding HCl (1 + 1). This should require about 2mL of HCl.
42、 Continue acidification with HCl (1 + 1) until a pHof 6 to 7 is reached, as indicated by a glass-electrode system.Dilute to 1 L. Add 1 mL of chloroform for preservation.Standardize against potassium biiodate solution.NOTE 2Phenylarsine oxide is more stable than sodium thiosulfate.However, sodium thi
43、osulfate may be used. The analyst should specifywhich titrant is used. For a stock solution (0.1 N), dissolve 24.82 g ofNa2S2O35H2O in boiled and cooled water and dilute to 1 L. Preserve byadding 5 mL of chloroform. For a dilute standard titrating solution (0.005N) transfer 25.00 mL of 0.1 N Na2S2O3
44、to a 500-mL volumetric flask.Dilute to the mark with water and mix completely. Do not prepare morethan 12 to 15 h before use.NOTE 3If the full bottle technique is used, 3.9007 g must be used tomake 0.0375 N.NOTE 4If sodium thiosulfate is used, prepare and preserve a 0.1 Nsolution as described in Not
45、e 1. Determine the exact normality by titrationagainst 0.025 N potassium biiodate solution. Dilute the appropriatevolume (nominally 250 mL) of standardized 0.1 N Na2S2O3solution to 1L. One millilitre of 0.025 N thiosulfate solution is equivalent to 0.2 mg ofoxygen. If the full bottle technique is fo
46、llowed, use 37.5 mL of sodiumthiosulfate solution and standardize to 0.0375 N.11.5 Starch SolutionMake a paste of6gofarrowrootstarch or soluble iodometric starch with cold water. Pour thepaste into 1 L of boiling water. Then add 20 g of potassiumhydroxide, mix thoroughly, and allow to stand for 2 h.
47、 Add 6mL of glacial acetic acid (99.5 %). Mix thoroughly and thenadd sufficient HCl (sp gr 1.19) to adjust the pH value of thesolution to 4.0. Store in a glass-stoppered bottle. Starchsolution prepared in this manner will remain chemically stablefor one year.NOTE 5Powdered starches such as thyodene
48、have been found ad-equate. Some commercial laundry starches have also been found to beusable.NOTE 6If the indicator is not prepared as specified or a proprietarystarch indicator preparation is used, the report of analysis shall state thisdeviation.11.6 Sulfuric Acid (sp gr 1.84)Concentrated sulfuric
49、 acid.One millilitre neutralizes about 3 mL of the alkaline iodidereagent.NOTE 7Sulfamic acid (3 g) may be substituted.11.7 Potassium Fluoride Solution (400 g/L)Dissolve 40 gof potassium fluoride in water and dilute to 100 mL. Thissolution is used in the procedure for eliminating ferric ioninterference. Store this solution in a plastic bottle.11.8 Potassium Oxalate Solution (20 g/L)Dissolve2gofpotassium oxalate in 100 mL of water. One millilitre of thissolution will reduce 1.1 mL of the KMnO4solution. Thissolution is used in the procedure for
