1、Designation: D3651 16Standard 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 SI units are to be regar
4、ded asstandard. The values given in parentheses are mathematicalconversion to inch-pound units that are provided for informa-tion only and are not considered standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of
5、the user of this standard to establish appro-priate safety and health 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
6、of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 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
7、and Inorganic ConstituentsD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this standard, refer toTerminology D1129.4. Summary of Test
8、Method4.1 This test method3,4is dependent upon the fact thatmetallic atoms, in the ground 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 thetran
9、smitted radiation will decrease in proportion to the amountof the ground state element in the flame. A hollow-cathodelamp whose cathode is made of the element to be determinedprovides the radiation.4.2 The metal atoms5,6to be measured are placed in thebeam of radiation by aspirating the specimen int
10、o an oxidant-fuel flame. A monochromator isolates the characteristic radia-tion from the hollow-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 absorption
11、differently, it becomes imperative to prepare standard sampleswith matrices similar to the unknown samples. This is accom-plished by preparing synthetic standard samples with similarcompositions as the unknowns. The standard samples andunknown samples are aspirated, the absorption readingsrecorded,
12、a calibration curve for the standard samplesconstructed, and the original sample concentration calculated.1This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved June
13、1, 2016. Published June 2016. Originallyapproved in 1978. Last previous edition approved in 2011 as D3651 11. DOI:10.1520/D3651-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informa
14、tion, refer to the standards Document Summary page onthe ASTM website.3Fletcher, G. F., and Collins, A. G., Atomic Absorption Methods of Analysis ofOil Field Brines: Barium, Calcium, Copper, Iron, Lead, Lithium, Magnesium,Manganese, Potassium, Sodium, Strontium, and Zinc, U.S. Bureau of Mines, Repor
15、tof Investigations 7861, 1974, 14 pp.4Collins, A. G., Geochemistry of Oil Field Waters, Elsevier Publishing Co.,Amsterdam, The Netherlands, 1974.5Angino, E. E., and Billings, G. K., Atomic Absorption Spectrophotometry inGeology, Elsevier Publishing Co., New York, NY, 1967.6Dean, J. A., and Rains, T.
16、 C., Editors, Flame Emission and Atomic AbsorptionSpectrophotometry, Volume 1, Theory, 1969, Volume 2, Components, 1971, andVolume 3, Elements and Matrices, 1975, Marcel Dekker, New York, NY.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbo
17、r Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 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 Io
18、nization interference is controlled by adding potas-sium.6.2 Matrix interferences, caused by 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 pro
19、cedure provided eliminates the interference effect of upto 750 mg/L calcium. Calcium interference 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 w
20、ill, therefore, be below the detection limit of thetest method.7. Apparatus7.1 Atomic Absorption 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 allinstrumen
21、tal parameters. Wavelengths other than 553.6 nm may be usedonly if they have been determined 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 somew
22、hat higher thanthe controlled operating pressure of the instrument by suitablevalves.8. Reagents 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 onA
23、nalytical Reagents of theAmerican Chemical Society,7where such specifications are available. 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, r
24、eference to water shall beunderstood to mean reagent water conforming to SpecificationD1193, 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 meth
25、od. Type III water wasspecified at the time of round-robin testing of this test method.8.3 Barium 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 wate
26、r. Onemillilitre of this solution contains 1 mg of barium. A purchasedstock solution of appropriate known 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 solut
27、ion to1 L with water. One millilitre of this solution contains 0.1 mgof barium.8.5 Potassium Solution (1mL=10mgK)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 s
28、olution ofappropriate known purity is also acceptable.8.6 Calcium Solution (1 mL = 10 mg Ca)Dissolve 54.66 gof 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 app
29、ropriate known purity is also acceptable.8.7 Sodium Solution (1 mL = 10 mg Na)Dissolve 25.14 gsodium chloride (NaCl) 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 appropriate knownpurity is also accept
30、able.8.8 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid, ultrapure or equivalent.8.9 Oxidant:8.9.1 Nitrous Oxide 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 acetylenecyl
31、inders, can be prevented from entering and damaging theburner head by replacing a cylinder which has only 690 kPa(100 psig) of acetylene remaining.8.11 Filter PaperPurchase suitable filter paper. Typicallythe filter papers have a pore size of 0.45-m membrane.Material such as fine-textured, acid-wash
32、ed, ashless paper, orglass fiber paper are acceptable. The user must first ascertainthat the filter paper is of sufficient purity to use withoutadversely affecting the bias and precision of the test method.9. Sampling9.1 Collect the sample in accordance with Practices D3370and D4841.9.2 Add 2.0 mL o
33、f 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, 2.5, 5.0, and 10 mL of barium standardsolution to 100-mL volumetric flasks.7Reagent Chemicals, American Chemical Soci
34、ety Specifications, AmericanChemical Society, Washington, 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. Pharmacopei
35、al Convention, Inc. (USPC), Rockville,MD.D3651 16210.2 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 solutionsto 100 mL with wa
36、ter.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 aninstrument into operation. However, the parameters that followhave been found suitable for some types of equipment.1
37、0.3.1 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 required is from 10 to 20min.10.3.3 Ignite an air-acetylene flame. Increase the fuel flowuntil the flame is luminescen
38、t. 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 sensitivity.10.3.4 Let the fuel-oxidant mixture burn for 10 to 15 minbefore operating the instrument.10.4 Operate the
39、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 reading. This value is used for roughly estimatingthe barium concentration in a sample.10.4.2 Operate the instrument
40、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 calibration curve from the barium con-centrations and absorbance readings by plotting the milligramsper litre of barium versu
41、s 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 Approximate Barium ConcentrationAspirate asample of water or brine (previously filtered through a 0.45-mfilter (8.11) int
42、o the flame and record the absorbance reading.The absorbance reading is compared to the 10 mg/L bariumstandard (10.4.1) absorbance reading.NOTE 2All absorbance readings on waters of high mineral contentshould be made as quickly as possible. Highly saline waters causeclogging of the burner which resu
43、lts 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.11.1.2.1 Transfer an aliquot of the water or brine, containingapproximately 0.1 to 0.5 mg of barium, to a 100-mLvolumetricflask.1
44、1.1.2.2 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 instrument in the concentration mode.11.3 Aspirate the sample and record the absorbance reading.12. Calculation12.1 Calculate the c
45、oncentration 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 3D/Vwhere:A = barium read from the calibration curve,D = dilution volume (volume the sample was diluted to),andV = volume of
46、 sample.13. Precision and Bias813.1 The precision and bias data presented in Table 1 forthis test method meet the requirements of Practice D2777. Thedata shown have been rounded from unrounded data in theresearch report.13.2 The precision and bias estimates in Table 1 are basedon an interlaboratory
47、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 laboratories performed single determi-nations on each of three days. Practice D2777 was used indeveloping these precision
48、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 toPractice D2777 77, which was in place at the time ofcollaborative testing. Under the allowances made in 1.4 ofPractice D
49、2777 13, these precision and bias data do meetexisting requirements for interlaboratory studies of CommitteeD19 test methods.14. Quality Control14.1 In order to be certain that analytical 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:8Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D19-1046. ContactASTM CustomerService a
