1、Designation: D 3986 07Standard Test Method forBarium in Brines, Seawater, and Brackish Water by Direct-Current Argon Plasma Atomic Emission Spectroscopy1This standard is issued under the fixed designation D 3986; the number immediately following the designation indicates the year oforiginal adoption
2、 or, in the case of revision, the year 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. Scope1.1 This test method covers the determination of dissolvedand total recoverable
3、 barium in brines, seawater, and brackishwaters by direct-current argon plasma atomic emission spec-troscopy (DCPAES).1.2 This test method has been tested in the range from 10mg/L to 20 mg/L. Samples shall be diluted to contain concen-trations within the calibration range (see 11.1 and 12.5). Higher
4、concentrations can also be determined by changing to a lesssensitive emission line.1.3 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 and
5、determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 3352 Test Method for Strontium Ion in Brackish Water,Seawater, and BrinesD 3370 Practices for Sampling Water from
6、 Closed ConduitsD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE 1097 Guide for Direct Current Plasma Emission Spec-trometry Analysis3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod refer to Terminology D 1129.3.2 De
7、finitions of Terms Specific to This Standard:3.2.1 total recoverable bariumrecoverable forms ofbarium that are determinable by the digestion method which isincluded in the procedure.3.2.2 laboratory control sample, na solution with a cer-tified concentration of barium.4. Summary of Test Method4.1 Th
8、is test method is dependent upon excitation of thebarium atom by a direct-current plasma source. When theexcited barium atom decays to a lower energy state it emitsenergy of a wavelength characteristic to the barium atom. Theintensity of this emitted radiation will increase in directproportion to th
9、e concentration of barium in the sample, whenworking in the linear response range.4.2 Since the variable and often high concentration ofmatrix materials in brines, seawater, and brackish water affectemission differently, it is a difficult task to prepare standardssufficiently similar to the samples.
10、 To overcome this problem,the standards are buffered with lithium ion and the samples arediluted and buffered in the same manner. The standards areused to construct a calibration curve and the concentration ofthe samples are calculated from this curve. Alternatively, theinstrument may be calibrated
11、using a blank and a standard orbracketing standards. The sample concentration can then beread out directly from the instrument.4.3 The 455.4-nm line has been found to be the mostsatisfactory for analysis.NOTE 1The barium lines at 230.4 nm, 233.5 nm, and 553.6 nm havebeen checked and found to be unsa
12、tisfactory for this analysis.4.4 Dissolved barium is determined by filtering the samplethrough a 0.45-m pore size membrane filter (Note 2)atthetime of sampling. This definition of “dissolved” barium isarbitrary since very fine crystals of barium sulfate may passthrough the membrane filter.NOTE 2Thes
13、e filters have been found to be contaminated to variousdegrees with heavy metals depending on the manufacturer. Care should beexercised in selecting a source for these filters. It has been found to be agood practice to wash the filters with nitric acid and then reagent waterbefore filtering a sample
14、.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 Aug. 1, 2007. Published August 2007. Originallyapproved in 1981. Last previous edition approved in 2002 as D 3
15、986 02.2For 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.1Copyright ASTM International, 100 Barr Harbor Drive,
16、PO Box C700, West Conshohocken, PA 19428-2959, United States.4.5 If there are no visible suspended solids in the sample,total recoverable barium may be determined on an acidifiedunfiltered sample in the same manner as dissolved barium.4.6 When the sample contains suspended solids total recov-erable
17、barium is determined by an acid digestion step todestroy organic and inorganic particulates.5. Significance and Use5.1 All waters containing acid soluble barium compoundsare known to be toxic. This test method is useful for thedetermination of barium in brines, seawater, and brackishwaters.5.2 Consu
18、mption, inhalation, or absorption of 500 to 600mg of barium is considered fatal to human beings. Lowerlevels may result in disorders of the heart, blood vessels, andnerves. The drinking water standards set the maximum con-taminant level for barium as 2 mg/L barium.6. Interferences6.1 Calcium interfe
19、res in concentrations greater than 300mg/L, however, this can be overcome by dilution of thesample. The method of standard additions as described in TestMethod D 3352 will also overcome this interference.6.2 High concentrations of sulfate anion are also known tointerfere in this test method by causi
20、ng precipitation of bariumin the form of barium sulfate.7. Apparatus7.1 See the manufacturers instruction manual on installa-tion and operation of direct-current argon plasma spectrom-eters. Refer to Guide E 1097 for information on DCP spec-trometers.8. Reagents8.1 Purity of ReagentsReagent grade ch
21、emicals shall beused in all tests. Unless otherwise indicated, it is intended thatreagents shall conform to the specifications of the committeeon analytical reagents of the American Chemical Society,3where such specifications are available. Other grades may beused provided it is first ascertained th
22、at the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Type II of Specification D 1193. Other reagent water typesmay be u
23、sed provided it is first ascertained that the water is ofsufficiently high purity to permit its use without adverselyaffecting the precision and bias of the test method. Type IIwater was specified at the time of round robin testing of thistest method.8.3 Barium Solution, Stock (1g/L Ba)Dissolve 1.77
24、87 g ofbarium chloride dihydrate (BaCl22H2O) in 100 mL of water,add 2 mL of nitric acid (sp gr 1.42) and dilute to 1 L. Apurchased stock solution of adequate purity is also acceptable.8.4 Barium Solution, Standard (50 mg/L)To 5.0 mL ofbarium stock solution add 5.0 mL of lithium solution (8.8) anddil
25、ute to 100 mL with HCl (1 + 499) (8.10). Working standards(11.1) are prepared from this solution.8.5 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).NOTE 3If a high reagent blank is obtained for either acid, distill theacid or use spectrograde acid.8.5.1 CautionWhen HCl is distil
26、led, an azeotropic mix-ture is obtained (approximately 6 N HCl).8.6 Hydrochloric Acid (1 + 499)Add 1 volume of hydro-chloric acid (sp gr 1.19) to 499 volumes of water.8.7 Lithium CarbonateHigh-purity lithium carbonate(Li2CO3).48.8 Lithium Solution (40 g/L Li)Dissolve 213.0 g ofLi2CO3in a minimum amo
27、unt of hydrochloric acid (sp gr 1.19)and dilute to 1 L with water.Approximately 250 mL of HCl (spgr 1.19) is needed to completely dissolve the lithium carbonate.If distilled HCl is used double the amount (see 8.5, Note 3).Store in a cleaned polyethylene or TFE-fluorocarbon bottle.8.9 Nitric Acid (sp
28、 gr 1.42)Concentrated nitric acid(HNO3).8.10 Nitric Acid (1 + 499)Add 1 volume of nitric acid (spgr 1.42) to 499 volumes of water.9. Hazards9.1 As with any method where pumping or aspiration ofsamples is employed, the viscosity of blank, standards, andsamples must be controlled within reasonable lim
29、its (that is, donot use reagent water standards to analyze oil field brines).9.2 To analyze waters containing a high percentage ofdissolved solids it is necessary to prepare standards and blankswith matrices similar to the unknown samples. In many casesthis is almost impossible and the problem can b
30、e solved byhigh dilution and introduction of lithium ion as an emissionenhancement buffer.10. Sampling10.1 Collect the sample in accordance with Practice D 3370.10.2 Preserve the samples with high-purity hydrochloricacid to a pH of two or less immediately at the time of collection(about 2 mL/L). If
31、only dissolved barium is to be determined,filter the samples through a 0.45-m membrane (Note 2) filterbefore acidification.11. Standardization and Calculation11.1 Prepare 100 mL each of a blank and 0.01, 0.02, 0.05,and 0.10 mg/L standards by diluting 5 mL of lithium solution3Reagent Chemicals, Ameri
32、can 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., and the United States Pharmacopeiaand National Formulary,
33、 U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4The sole source of supply of the apparatus known to the committee at this timeis LI 30 or its equivalent from Spex Industries, Inc., Box 798, Metuchen, NJ 08840.If you are aware of alternative suppliers, please provide this information to AS
34、TMInternational Headquarters. Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.D 3986 072(8.8) and 20, 40, 100, and 200 L of barium standard solution(8.4) with HCl (1 + 499). Prepare standards and blank eachtime the test is per
35、formed.11.2 Aspirate the blank and standards. AspirateHNO3(1 + 499) between each standard and sample.11.3 Using the instrument software, verify that the instru-ment calibration is within user acceptable QC limits and reportthe barium concentrations accordingly.12. Procedure12.1 When determining diss
36、olved barium the sample shouldbe previously filtered through a 0.45-m membrane filter andacidified (10.2) then proceed with 12.5.12.2 When determining total recoverable barium and pre-cipitation has occurred or large amounts of suspended solidsare present, add 5 mL each of nitric acid (sp gr 1.42) a
37、nd HCl(sp gr 1.19) to 100 mLof the sample and proceed with 12.3 and12.4.12.3 Heat the samples on a steam bath or hot plate until thevolume is reduced to 15 to 20 mL, making certain that thesamples do not boil.NOTE 4When analyzing samples of brines or samples containinglarge amounts (5 %) of dissolve
38、d solids. The amount of reduction involume is left to the discretion of the analyst.12.4 Cool and filter the samples through fine ashless filterpaper into 100-mL volumetric flasks. Wash the filter paper atleast three times with water and adjust to 100 mL volume.12.5 Approximate Barium ConcentrationA
39、spirate thesample and compare its emission intensity to that of the bariumsolution standard (50 mg/L, 8.4). It should be stressed that thisis not an accurate result and is to be used only to calculate thequantity of sample needed for dilution in 12.6.12.6 Transfer an aliquot of the sample containing
40、 approxi-mately 0.001 to 0.01 mg of barium to a 100-mL volumetricflask. Add 5 mL of lithium solution and dilute to volume withHCl (1 + 499).12.7 Aspirate the sample and record its emission intensity at455.4 nm. Concentrations may be read directly if this capabil-ity is provided. Aspirate HNO3(1 + 49
41、9) between samples andstandards.13. Precision and Bias513.1 PrecisionThe overall and single-operator precisionof this method within its designated range for brines, seawater,and brackish water varies with the quantity tested in accor-dance with Table 1. Eight operators from six laboratoriesparticipa
42、ted in this study by determining three replicates, ondifferent days, at each concentration level as listed in Table 2.13.2 BiasRecoveries of barium from brines and selectedwater matrices were as shown in Table 1.13.3 It is the users responsibility to ensure the validity ofthis test method for waters
43、 of untested matrices.13.4 Precision and bias for this test method conforms toPractice D 2777-77, which was in place at the time ofcollaborative testing. Under the allowances made in 1.4 of D2777-06, these precision and bias data do meet existingrequirements for interlaboratory studies of Committee
44、D19 testmethods.14. Quality Control (QC)14.1 The following quality control information is recom-mended for the determination of Barium in Brines, Seawater,and Brackish Water.14.2 The instrument shall be calibrated using a minimum offour calibration standards and a calibration blank. The calibra-tion
45、 correlation coefficient shall be equal to or greater than0.990. In addition to the initial calibration blank, a calibrationblank should be analyzed at the end of the batch run to ensurecontamination was not a problem during the batch analysis.14.3 An instrument check standard shall be analyzed at a
46、minimum frequency of 10 % throughout the batch analysis.The value of the instrument check standard shall fall between80 % and 120 % of the true value.14.4 Two method blanks shall be prepared ensuring that anadequate method blank volume is present for a minimum ofseven repetitive analysis. The standa
47、rd deviation of the methodblank is used to determine the minimum detectable concentra-tion of each sample and control in the batch.14.5 A Laboratory Control Sample shall be analyzed witheach batch of sample at a minimum frequency of 10 %.14.6 If the QC for the sample batch is not within theestablish
48、ed control limits, reanalyze the samples or qualify theresults with the appropriate flags, or both (Practice D 5847).14.7 Blind control samples should be submitted by anoutside agency in order to determine the laboratory perfor-mance capabilities.15. Keywords15.1 barium; brackish water; brines; dire
49、ct-current argonplasma atomic emission; seawater; spectroscopy5Supporting data are available from ASTM International Headquarters. RequestRR: D19-1071.TABLE 1 Determination of Precision and Bias for Barium byDirect-Current Argon Plasma Atomic Emission SpectroscopyAmountAdded,mg/LAmountFound,mg/LSt,mg/LSO,mg/L%,BiasStatisticallySignificant95 % Level10.0 10.88 1.076 0.39 + 8.8 yes15.0 15.50 0.664 0.48 + 3.3 yes20.0 20.32 0.756 0.70 + 1.6 yesTABLE 2 Composition of Artificial Brine Samples, g/LSample No. 1 2 3ChemicalCompound:NaClA100.0 50.0 150.0KClA1.00 2.0
