1、Designation: D3986 11Standard Test Method forBarium in Brines, Seawater, and Brackish Water by Direct-Current Argon Plasma Atomic Emission Spectroscopy1This standard is issued under the fixed designation D3986; the number immediately following the designation indicates the year oforiginal adoption o
2、r, in the case of revision, the year of last revision. A number 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 dissolvedand total recoverable b
3、arium 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). Higherco
4、ncentrations can also be determined by changing to a lesssensitive emission line.1.3 The values stated in SI units are 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 wit
5、h its use. It is theresponsibility of 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
6、WaterD3352 Test Method for Strontium Ion in Brackish Water,Seawater, and BrinesD3370 Practices for Sampling Water from Closed ConduitsD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE1097 Guide for Direct Current Plasma-Atomic EmissionSpectrometry
7、 Analysis3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 total recoverable barium, nrecoverable bariumforms that are determinable by the digestion method that isincluded in the procedure
8、.3.2.2 laboratory control sample, na solution with a cer-tified concentration of barium.4. Summary of Test Method4.1 This 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 wavel
9、ength characteristic to the barium atom. Theintensity of this emitted radiation will increase in directproportion to the 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 bra
10、ckish water affectemission differently, it is a difficult task to prepare standardssufficiently similar to the samples. 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 cu
11、rve and the concentration ofthe samples are calculated from this curve. Alternatively, theinstrument may be calibrated 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 mostsat
12、isfactory for analysis.NOTE 1The barium lines at 230.4 nm, 233.5 nm, and 553.6 nm havebeen checked and found to be unsatisfactory 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 “
13、dissolved” barium isarbitrary since very fine crystals of barium sulfate may passthrough the membrane filter.NOTE 2These 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 h
14、as been found to be agood practice to wash the filters with nitric acid and then reagent waterbefore filtering a sample.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
15、approved Sept. 1, 2011. Published September 2011. Originallyapproved in 1981. Last previous edition approved in 2007 as D3986 07. DOI:10.1520/D3986-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStan
16、dards volume information, refer to the standards Document Summary page onthe ASTM website.1*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.4.5 If there are no visible s
17、uspended 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 barium is determined by an acid digestion step todestroy organic and inorganic particulate
18、s.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 Consumption, inhalation, or absorption of 500 to 600mg of barium is considered fatal to human b
19、eings. 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 interferes in concentrations greater than 300mg/L, however, this can be overcome by dilution of t
20、hesample. The method of standard additions as described in TestMethod D3352 will also overcome this interference.6.2 High concentrations of sulfate anion are also known tointerfere in this test method by causing precipitation of bariumin the form of barium sulfate.7. Apparatus7.1 See the manufacture
21、rs instruction manual on installa-tion and operation of direct-current argon plasma spectrom-eters. Refer to Guide E1097 for information on DCP spectrom-eters.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatreagents s
22、hall 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 that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy
23、 of the determination.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Type II of Specification D1193. Other reagent water typesmay be used provided it is first ascertained that the water is ofsufficiently high purity to permit i
24、ts 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 1.7787 g ofbarium chloride dihydrate (BaCl22H2O) in 100 mL of water,add 2 mL of nitric acid (sp g
25、r 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) anddilute to 100 mL with HCl (1 + 499) (8.10). Working standards(11.1) are prepared from this solut
26、ion.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 distilled, an azeotropic mix-ture is obtained (approximately 6 N HCl).8.6 Hydrochloric Acid (1 + 49
27、9)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 amount of hydrochloric acid (sp gr 1.19)and dilute to 1 L with water.Approximately 250 mL of HCl
28、 (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 gr 1.42)Concentrated nitric acid(HNO3).8.10 Nitric Acid (1 + 499)Add 1 volume of nitric acid
29、 (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 limits (that is, donot use reagent water standards to analyze oil field brines).9.2 To analyze w
30、aters 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 be solved byhigh dilution and introduction of lithium ion as an emissionenhancement buffer.10.
31、 Sampling10.1 Collect the sample in accordance with Practice D3370.10.2 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 only dissolved barium is to be determined,filter the samples through a 0.45-m membrane (Note 2
32、) 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 solution(8.8) and 20, 40, 100, and 200 L of barium standard solution3Reagent Chemicals, American Chemical Society Specification
33、s, 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. Pharmacopeial Convention, In
34、c. (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 ASTMInternational Headquarters. Your
35、 comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.D3986 112(8.4) with HCl (1 + 499). Prepare standards and blank eachtime the test is performed.11.2 Aspirate the blank and standards. AspirateHNO3(1 + 499) between each standard and s
36、ample.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 dissolved barium the sample shouldbe previously filtered through a 0.45-m membrane filter andacidif
37、ied (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) and HCl(sp gr 1.19) to 100 mLof the sample and proceed with 12.3 and12.4.12.3 Heat the samples o
38、n 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 dissolved solids. The amount of reduction involume is left to the discretion of the analyst.12.4 Cool a
39、nd 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 ConcentrationAspirate thesample and compare its emission intensity to that of the bariumsolution standard (50
40、 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 approxi-mately 0.001 to 0.01 mg of barium to a 100-mL volumetricflask. Add 5 mL of lithium sol
41、ution 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 + 499) between samples andstandards.13. Precision and Bias513.1 PrecisionThe overall and single-ope
42、rator 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 laboratoriesparticipated in this study by determining three replicates, ondifferent days, at each concentration leve
43、l 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 of untested matrices.13.4 Precision and bias for this test method conforms toPractice D2777-77
44、, 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 D19 test methods.14. Quality Control (QC)14.1 The following quality control information is reco
45、m-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 correlation coefficient shall be equal to or greater than0.990. In addition to the initial ca
46、libration 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 aminimum frequency of 10 % throughout the batch analysis.The value of the instrument check stan
47、dard 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 analyses. The standard deviation of the methodblank is used to determine the minimum detectable concentra-tion of
48、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 theestablished control limits, reanalyze the samples or qualify theresults with the appropriate flags, or
49、both (Practice D5847).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; direct-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 1
