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2、n American National StandardStandard Test Methods forIodide and Bromide Ions in Brackish Water, Seawater, andBrines1This standard is issued under the fixed designation D 3869; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
3、r of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods2 cover the determination of soluble iodide and bromide ions, or both, in brackish water, sea
4、water, and brines. Four test methods are given as follows:1.1.1 Test Method A for both Iodide and Bromide Ions Volumetric, for concentrations from 0.2 to 2000 mg/L iodide and from 5 to 6500 mg/L bromide (Sections 7-15).1.1.2 Test Method B for Iodide IonColorimetric, for concentrations from 0.2 to 20
5、00 mg/L iodide (Sections 16-25).1.1.3 Test Method C for Iodide IonSelective electrode, for concentrations from 1 to 2000 mg/L iodide (Sections 26-34).1.1.4 Test Method D for Bromide IonColorimetric, for concentrations from 40 to 6500 mg/L bromide (Sections35-44).1.2 Test Method A is intended for use
6、 on all brackish waters, seawaters, and brines that contain appreciable amounts of iodide or bromide ions or both. Test Methods B, C, and D, because of their rapidity and sensitivity, are recommended for the analysis of brackish waters, seawaters, and brines in the field and in the laboratory.1.3 Sa
7、mples containing from 0.2 to 2000 mg/L of iodide or5 to 6500 mg/L of bromide may be analyzed by these methods.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate sa
8、fety and health practices and determine the applica-1 These test methods are under the jurisdiction of ASTM Committee D19 on Water and are the direct responsibility of Subcommittee D19.05 on Inorganic Constituents in Water.Current edition approved March 1, 2004. Published April 2004. Originally appr
9、oved in 1979. Last previous edition approved in 1999 as D 3869 95 (1999).2 Additional information is contained in the following references:Collins, A. G., Geochemistry of Oilfield Waters, Elsevier, New York, N. Y., 1975,496 pp.American Petroleum Institute, API Recommended Practice for Analysis ofbil
10、ity of regulatory limitations prior to use. For specificprecautionary statements, see 20.2 and 39.2.2. Referenced Documents2.1 ASTM Standards: 3D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Co
11、mmittee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 5810 Guide for Spiking Into Aqueous SamplesD 5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water AnalysisE 60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecula
12、r Absorption SpectrometryE 200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical AnalysisE 275 Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near Infrared Spectrophotom- eters3. Terminology3.1 DefinitionsFor definit
13、ions of terms used in these test methods, refer to Terminology D 1129.4. Significance and Use4.1 Identification of a brackish water, seawater, or brine is determined by comparison of the concentrations of their dissolved constituents. The results are used to evaluate the origin of the water, determi
14、ne if it is a possible pollutant or determine if it is a commercial source of a valuable constituent such as iodine or bromine.Oilfield Waters, Subcommittee on Analysis of Oilfield Waters, API RP, 45 2nd ed, 1968, 49 pp.Hoke, S. H, Fletcher, G. E., and Collins, A. G., “Fluoride and Iodide Selective
15、Electrodes Applied to Oilfield Brine Analysis.” US Department of Energy, Report of Investigations, BETC/RI-78/7, 1978.3 For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standards volume information, refer
16、 to the standards Document Summary page on the ASTM website.*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1D 3869 045. Reagents5.1 Purity of ReagentsReagent grade che
17、micals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the specification of the Committee on Analytical Reagents of the American Chemical Society,4 where such specifications are available. Other grades may be used, provided it is first ascert
18、ained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.5.2 Purity of Water Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to Specification D 1193, Type I. Other reagent water typ
19、es may be used provided it is first ascertained that the water is of sufficiently high purity to permit its use without adversely affecting the precision and bias of the test method. Type III water was specified at the time of round robin testing of this test method.6. Sampling6.1 Collect the sample
20、 in accordance with Practices D 3370.TEST METHOD AVOLUMETRIC FOR IODIDE AND BROMIDE7. Scope7.1 This test method is applicable to brackish waters, seawaters, and brines, and is recommended for such waters containing appreciable amounts of iodide or bromide, or both. The test method can be used for co
21、ncentrations as high as 2000 mg/L iodide and 6500 mg/L bromide.8. Summary of Test Method8.1 Iodide in the sample is oxidized with bromine to iodate in a buffered solution, the excess bromine is decomposed with sodium formate, and the iodate reacts with added iodide to form iodine which is titrated w
22、ith sodium thiosulfate.8.2 Iodide and bromide are oxidized to iodate and bromate, respectively, with hypochlorite. The excess hypochlorite is destroyed with sodium formate, leaving iodate and bromate to react with added iodide to liberate iodine which is titrated with sodium thiosulfate.8.3 The brom
23、ide concentration is calculated by difference between the iodide and combined iodide and bromide deter- minations.9. Interferences9.1 Iron, manganese, and organic matter can interfere (Note1). They are removed by precipitation and filtration. Remaining traces of iron are masked with fluoride.NOTE 1B
24、rines containing surfactants can cause emulsion problems, in which case a suitable emulsion breaker can be used.4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Soc
25、iety, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.10. Apparatus10.1 Mechanical Bottle Shaker.10.2 Bottles, 200-mL, for use on mechanical shaker.10.3
26、 Pipets.10.4 Hot-Water Bath, thermostatically controlled to 6 1C.10.5 Erlenmeyer Flasks, 250-mL.11. Reagents11.1 Acetic Acid, glacial.11.2 Ammonium Molybdate SolutionDissolve 2 g of am- monium molybdate in water and dilute to 100 mL.11.3 Bromine Water (Saturated)Add to 250 mL of water slightly more
27、liquid bromine (8 to 10 mL) than will dissolve on shaking. Store in a glass-stoppered amber bottle.11.4 Calcium Carbonate (CaCO3), powdered.11.5 Calcium Oxide (CaO), anhydrous powdered.11.6 Hydrochloric Acid (1 + 1)Add 1 volume of HCl (sp gr 1.19) to 1 volume of water.11.7 Hydrochloric Acid (1 + 3)A
28、dd 1 volume of HCl (sp gr 1.19) to 3 volumes of water.11.8 Hydrochloric Acid (1 + 199)Add 1 volume of HCl(sp gr 1.19) to 199 volumes of water.11.9 Methyl Red Indicator Solution (0.1 g/L)Dissolve0.01 g of water-soluble methyl red in water and dilute to 100mL.11.10 Potassium Fluoride (KF2H2O)crystalli
29、ne.11.11 Potassium Iodide (KI), crystals, free of iodates whentested in accordance with American Chemical Society (ACS)specifications.11.12 Sodium Acetate Solution (275 g/L)Dissolve 275 g of sodium acetate trihydrate (NaC2H3O23H2O) in water, to dilute to 1 L, and filter.11.13 Sodium Chloride (NaCl),
30、 crystals, which, in addition to satisfying ACS specifications, must be free of iodide, iodate, bromide, and bromate.11.14 Sodium Formate Solution (500 g/L)Dissolve 50 g of sodium formate (NaCHO2) in hot water and dilute to 100 mL. This solution must be freshly prepared.11.15 Sodium Hypochlorite Sol
31、utionUse a fresh commer- cial sodium hypochlorite or bleach solution containing ap- proximately 5 % NaClO.11.16 Sodium Thiosulfate Solution (0.1 N)Prepare and standardize as directed in Practice E 200.11.17 Sodium Thiosulfate Solution (0.01 N)With a cali- brated pipet transfer 25 mL of the 0.1 N Na2
32、S 2O3 solution intoa 250-mL volumetric flask. Dilute to the mark with water that has been freshly boiled and cooled then mix well. This solution shall be prepared not more than 2 days before it is to be used.11.18 Starch Indicator SolutionMake a paste of 6 g of arrowroot or soluble iodometric starch
33、 with cold water. Pour the paste into 1 L of boiling water. Add 20 g of KOH, mix thoroughly, and allow to stand for 2 h. Add 6 mL of glacial acetic acid. Mix again and add sufficient HCl (sp gr 1.19) to adjust the pH to 4.0. Store in a glass-stoppered bottle. Starch solution prepared in this manner
34、will remain chemically stable for at least 1 year.11.18.1 If a proprietary starch indicator powder is used, it shall be so indicated in reporting the results of the analysis.212. ProcedureD 3869 04C = corrected millilitres of Na2S 2O3 solution,12.1 To remove iron, manganese, and organic matter fromt
35、he sample, add exactly 100 mL of sample to a bottle. Add 1 g of calcium oxide, stopper, and place the mixture in a shaker for1 h. Allow the mixture to stand overnight and filter on a dry folded filter, discarding the first 20 mL that come through. Brines with specific gravities less than 1.009 may b
36、e filtered without standing overnight. Prepare a blank in the same manner.12.2 Transfer an aliquot of the filtrate containing 1 to 2 mg of iodide to a 250-mL Erlenmeyer flask. Add sufficient water to provide a total volume of 75 mL.12.3 Add 3 drops of methyl red indicator. Add HCl(1 + 199) dropwise
37、until the mixture is just slightly acid.12.4 Add 10 mL of sodium acetate solution, 1 mL of glacial acetic acid, 4 mL of bromine water, and allow to stand for 5 min.12.5 Add 2 mL of sodium formate solution, blow out any bromine vapor from the neck of the flask, and wash down the sides with water.12.6
38、 When the solution is completely colorless, add 0.2 g ofKF and 0.5 g of KI. Mix until dissolved and add 15 mL of HCl(1 + 1).12.7 For final treatment and titration of the sample, proceed as directed in (12.13).12.8 To determine the combined iodide and bromide, trans- fer an aliquot of the filtrate (1
39、2.1) containing 1 to 2 mg of bromide to a 250-mL Erlenmeyer flask. Add sufficient water to make the total volume 75 mL.12.9 If necessary add sufficient NaCl to produce a 3-g chloride content. Add, in order, 10 mL of sodium hypochlorite solution and approximately 0.4 g of CaCO3(or enough so that appr
40、oximately 0.1 g will remain after the next step).12.10 Adjust the pH of the solution with HCl (1 + 3) to a pH between 5.5 and 6.0. Heat at 90C for 10 min. (A small amount of undissolved CaCO3 should remain at this point.)12.11 Remove the flask and cautiously add 10 mL of sodium formate solution, ret
41、urn the flask to the water bath, and keep the contents hot for 5 min more. Observe the timing closely. Rinse down the inside of the flask with a few millilitres of water and allow the solution to cool to room temperature. Do not use a water bath.12.12 Add 3 drops of ammonium molybdate solution, 0.5
42、g of KF (if iron is present), 0.5 g of KI, mix until dissolved, and acidify with 15 mL of HCl (1 + 1).12.13 Titrate the sample (12.7) for iodide or the sample(12.12) for combined iodide and bromide with 0.01 N sodium thiosulfate solution using starch indicator. Disregard any return of blue color aft
43、er the endpoint.13. Calculation13.1 Calculate the concentration of iodide and bromide ions in milligrams per litre as follows:13.2 Iodide:C 5 E 2 DE = millilitres of Na2S2O3, sample solution, andD = millilitres of Na2S2O3 blank solution.CNI2, mg/L 5 S 3 21150where:N= normality of Na2S2O 3 solution,
44、andS= millilitres of sample.13.3 Bromide:C 5 E 2 DCNBr 2, mg/L 5 S 3 13320 2 Xwhere:X= concentration of I as determined above.14. Precision and Bias 514.1 The overall precision (ST) and single-operator preci- sion ( So) of this test method within their designated ranges vary with the quantity being
45、tested in accordance with Table 1 and Table 2.14.2 The bias of the test method determined from recoveries of known amounts of iodide and bromide in a series of prepared standards are given in Table 1 and Table 2.NOTE 2The precision and bias estimates are based on the interlabo- ratory study on four
46、artificial brine samples containing various amounts of iodide, bromide, and interfering ions as shown in Table 3. Two analysts in each of three laboratories performed duplicate determinations on each of2 days. Practice D 2777 was used in developing these precision and bias estimates.14.3 Precision and bias for this test method conforms to Practice D 2777-77, which was in place at the time of collaborative testing. Under the allowance