1、Designation: D3651 11Standard Test Method forBarium in Brackish Water, Seawater, and Brines1This standard is issued under the fixed designation D3651; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of solublebarium ion in brackish water, sea-water, and brines by atomicabsorption spectrophotom
3、etry.1.2 The actual working range of this test method is 1 to 5mg/L barium.1.3 This test method was used successfully on artificialbrine samples. It is the users responsibility to ensure thevalidity of this test method for waters of untested matrices.1.4 The values stated in either SI or inch-pound
4、units are tobe regarded as the standard. The values given in parenthesesare for information only.1.5 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
5、practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on Wa
6、terD3370 Practices for Sampling Water from Closed ConduitsD4691 Practice for Measuring Elements in Water by FlameAtomic Absorption SpectrophotometryD4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic ConstituentsD5810 Guide for Spiking into Aqueous Samples
7、D5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 For definitions of terms used in this test method, refer toTerminology D1129.4. Summary of Test Method4.1 This test method3is dependent upon the fact thatmetallic atoms, in the grou
8、nd state, will absorb light of thesame wavelength they emit when excited. When radiation froma given excited element is passed through a flame containingground state atoms of that element, the intensity of thetransmitted radiation will decrease in proportion to the amountof the ground state element
9、in the flame. A hollow-cathodelamp whose cathode is made of the element to be determinedprovides the radiation.4.2 The metal atoms4to be measured are placed in the beamof radiation by aspirating the specimen into an oxidant-fuelflame. A monochromator isolates the characteristic radiationfrom the hol
10、low-cathode lamp and a photosensitive devicemeasures the attenuated transmitted radiation.4.3 Since the variable and sometimes high concentrations ofmatrix materials in the waters and brines affect absorptiondifferently, it becomes imperative to prepare standard sampleswith matrices similar to the u
11、nknown samples. This is accom-plished by preparing synthetic standard samples with similarcompositions as the unknowns. The standard samples and1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsi
12、n Water.Current edition approved Sept. 1, 2011. Published September 2011. Originallyapproved in 1978. Last previous edition approved in 2007 as D3651 07. DOI:10.1520/D3651-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
13、 Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Fletcher, G. F. and Collins,A. G., Atomic Absorption Methods of Analysis of OilField Brines: Barium, Calcium, Copper, Iron, Lead, Lithium, Magnesium, Manga-nese, Potassium, Sodium, Stro
14、ntium, and Zinc, U. S. Bureau of Mines, Report ofInvestigations 7861, 1974, 14 pp. Collins, A. G., Geochemistry of Oil Field Waters,Elsevier Publishing Co., Amsterdam, The Netherlands, 1974.4Angino, E. E. and Billings, G. K., Atomic Absorption Spectrophotometry inGeology, Elsevier Publishing Co., Ne
15、w York, NY 1967. Dean, J. A. and Rains, T.C.,Editors, Flame Emission and Atomic Absorption Spectrophotometry, Vol. 1, Theory,1969, Vol 2, Components, 1971, and Vol 3, Elements and Matrices, 1975, MarcelDekker, New York, NY.1*A Summary of Changes section appears at the end of this standard.Copyright
16、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.unknown samples are aspirated, the absorption readings re-corded, a calibration curve for the standard samples con-structed, and the original sample concentration calculated.5. Significance and Us
17、e5.1 Since water containing acid-soluble barium compoundsis known to be toxic, this test method serves the useful purposeof determining the barium in brackish water, seawater, andbrines.6. Interferences6.1 Ionization interference is controlled by adding potas-sium.6.2 Matrix interferences, caused by
18、 high concentrations ofvaried ions, and spectral interference, caused by high calciumconcentrations, are controlled by matching the matrices.6.3 This test method is subject to calcium interference, butthe procedure provided eliminates the interference effect of upto 750 mg/L calcium. Calcium interfe
19、rence can also beminimized by using a secondary wavelength of 455.4 nm.6.4 In high sulfate waters, such as seawater, barium will beprecipitated as barium sulfate and will not be present as solublebarium and will, therefore, be below the detection limit of thetest method.7. Apparatus7.1 Atomic Absorp
20、tion Spectrophotometerfor use at 553.6nm. A general guide for the use of flame atomic absorptionapplications is given in Practice D4691.NOTE 1The manufacturers instructions should be followed for allinstrumental parameters. Wavelengths other than 553.6 nm may be usedonly if they have been determined
21、 to be equally suitable.7.1.1 Multielement Hollow-Cathode Lamps are availableand have been found satisfactory.7.2 Pressure-Reducing ValvesThe supplies of fuel andoxidant shall be maintained at pressures somewhat higher thanthe controlled operating pressure of the instrument by suitablevalves.8. Reag
22、ents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee onAnalytical Reagents of theAmerican Chemical Society,5where such specifications are available.
23、 Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Unless otherwise indicated, reference to water shall beunderstood to mean reagent water conforming to SpecificationD1193,
24、 Type I. Other reagent water types may be usedprovided it is first ascertained that the water is of sufficientlyhigh purity to permit its use without adversely affecting theprecision and bias of the test method. Type III water wasspecified at the time of round-robin testing of this test method.8.3 B
25、arium Solution, Stock (1 mL = 1 mg Ba)Dissolve1.779 g of barium chloride (BaCl22H2O) in 50 mL ofconcentrated hydrochloric acid (HCl) (sp gr 1.19) and about700 mL of water. Dilute the solution to 1 L with water. Onemillilitre of this solution contains 1 mg of barium. A purchasedstock solution of adeq
26、uate purity is also acceptable.8.4 Barium Solution, Standard (1 mL = 0.1 mg Ba)Add100 mL of barium solution stock to 50 mL of concentrated HCl(sp gr, 1.19) and about 600 mL of water. Dilute the solution to1 L with water. One millilitre of this solution contains 0.1 mgof barium.8.5 Potassium Solution
27、 (1 mL = 10 mg K)Dissolve 19.07g of potassium chloride (KCl) in about 700 mL of water. Dilutethe solution to 1 L with water. One millilitre of this solutioncontains 10 mg of potassium. A purchased stock solution ofadequate purity is also acceptable.8.6 Calcium Solution (1 mL = 10 mg Ca)Dissolve 54.6
28、6g of calcium chloride hexahydrate (CaCl26H2O) in 500 mL ofwater. Dilute the solution to 1 L with water. One millilitre ofthis solution contains 10 mg of calcium. A purchased stocksolution of adequate purity is also acceptable.8.7 Sodium Solution (1 mL = 10 mg Na)Dissolve 25.14 gsodium chloride (NaC
29、l) in 500 mL of water. Dilute the solutionto 1 L with water. One millilitre of this solution contains 10 mgof sodium. A purchased stock solution of adequate purity isalso acceptable.8.8 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid, ultrapure or equivalent.8.9 Oxidant:8.9.1 Nitrous O
30、xide is the oxidant required for this testmethod.8.10 Fuel:8.10.1 AcetyleneStandard, commercially available acety-lene is the usual fuel. Acetone, always present in acetylenecylinders, can be prevented from entering and damaging theburner head by replacing a cylinder which has only 690 kPa(100 psig)
31、 of acetylene remaining.9. Sampling9.1 Collect the sample in accordance with Practices D3370and D4841.9.2 Add 2.0 mL of HCl per litre of water to preventprecipitation of soluble barium.10. Calibration and Standardization10.1 Prepare standards of 0.0, 1.0, 2.5, 5.0, and 10 mg/L ofBa by adding 0, 1.0,
32、 2.5, 5.0, and 10 mL of barium standardsolution to 100-mL volumetric flasks.10.2 Add to each standard 5 mL of concentrated HCl (sp gr1.19), 10 mL of potassium solution (1 mL = 10 mg of K), 7.5mL of calcium solution (1 mL = 10 mg of Ca), and 15 mL ofsodium solution (1 mL = 10 mg of Na). Dilute these
33、solutionsto 100 mL with water.10.3 The method of operation varies with different modelsof atomic absorption spectrophotometers. Therefore, no at-tempt is made here to describe in detail the steps for placing an5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Wa
34、shington, 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 National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D3651 1
35、12instrument into operation. However, the parameters that followhave been found suitable for some types of equipment.10.3.1 Turn on the instrument.10.3.2 Apply the current to the cathode lamp as suggestedby the manufacturer:Allow the instrument to warm up until theenergy source stabilizes. The time
36、required is from 10 to 20min.10.3.3 Ignite an air-acetylene flame. Increase the fuel flowuntil the flame is luminescent. Let the flame stabilize (about1015 s). Switch to the nitrous oxide. Provide concentration ofmetal in accordance with the instructions outlined by themanufacturer, to give maximum
37、sensitivity.10.3.4 Let the fuel-oxidant mixture burn for 10 to 15 minbefore operating the instrument.10.4 Operate the instrument in the absorption mode andaspirate the 0 mg/L barium standard and set the instrument tozero absorbance.10.4.1 Aspirate the 10 mg/L barium standard and record theabsorbance
38、 reading. This value is used for roughly estimatingthe barium concentration in a sample.10.4.2 Operate the instrument in the concentration modeand optimize the instrument settings.10.4.3 Aspirate the 1.0, 2.5, and 5.0 mg/L barium standardsand record the absorbance readings.10.4.4 Construct a calibra
39、tion curve from the barium con-centrations and absorbance readings by plotting the milligramsper litre of barium versus the absorbance readings.11. Procedure11.1 Determine barium at the 553.6-nm wavelength with anitrous oxide-acetylene flame.11.1.1 Operate instrument in an absorption mode.11.1.2 App
40、roximate Barium ConcentrationAspirate asample of water or brine (previously filtered through a No. 325(0.45-m) filter) into the flame and record the absorbancereading. The absorbance reading is compared to the 10 mg/Lbarium standard (10.4.1) absorbance reading.NOTE 2All absorbance readings on waters
41、 of high mineral contentshould be made as quickly as possible. Highly saline waters causeclogging of the burner which results in large errors in the determinations.In some instances, the oxidant and fuel have to be turned off and theburner cleaned before completing a series of determinations.11.1.2.
42、1 Transfer an aliquot of the water or brine, containingapproximately 0.1 to 0.5 mg of barium, to a 100-mLvolumetricflask.11.1.2.2 Add 5.0 mL of concentrated HCl (sp gr 1.19) and10 mL of potassium solution (1 mL = 10 mg K) to the flask.Dilute the sample to 100 mL with water.11.2 Operate the instrumen
43、t in the concentration mode.11.3 Aspirate the sample and record the absorbance reading.12. Calculation12.1 Calculate the concentration of barium ion in theoriginal sample in milligrams per litre using the calibrationcurve prepared in 10.4.2 through 10.4.4 as follows:Barium concentration, mg/L 5 A 3
44、D/Vwhere:A = barium read from the calibration curve,D = dilution volume (volume the sample was diluted to),andV = volume of sample.13. Precision and Bias613.1 The precision and bias data presented in Table 1 forthis test method meet the requirements of Practice D2777. Thedata shown have been rounded
45、 from unrounded data in theresearch report.13.2 The precision and bias estimates in Table 1 are basedon an interlaboratory study on four artificial brine samplescontaining various amounts of barium and interfering ions asshown in Table 2. One analyst in one laboratory and twoanalysts in each of four
46、 laboratories performed single determi-nations on each of three days. Practice D2777 was used indeveloping these precision and bias estimates. It is the usersresponsibility to ensure the validity of this test method forwaters of untested matrices.13.3 Precision and bias for this test method conforms
47、 toPractice D2777-77, which was in place at the time of collab-orative testing. Under the allowances made in 1.4 of D2777-08,these precision and bias data do meet existing requirements forinterlaboratory studies of Committee D-19 test methods.14. Quality Control14.1 In order to be certain that analy
48、tical values obtainedusing these test methods are valid and accurate within theconfidence limits of the test, the following QC procedures mustbe followed when analyzing barium.14.2 Calibration and Calibration Verification:14.2.1 Analyze at least three working standards containingconcentrations of ba
49、rium that bracket the expected sampleconcentration prior to analysis of samples to calibrate theinstrument.14.2.2 Verify instrument calibration after standardization byanalyzing a standard at the concentration of one of thecalibration standards. The absorbance shall fall within 4% ofthe absorbance from the calibration. Alternately, the concen-tration of a mid-range standard should fall within +/- 15% ofthe known concentration.14.2.3 If calibration cannot be verified, recalibrate theinstrument.14.3 Initial Demonstration of Laboratory Capability:14.3.1 If a laborat
