1、Designation: D 3352 08aStandard Test Method forStrontium Ion in Brackish Water, Seawater, and Brines1This standard is issued under the fixed designation D 3352; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of solublestrontium ion in brackish water, seawater, and brines by atomicabsorption sp
3、ectrophotometry.1.2 Samples containing from 5 to 2100 mg/L of strontiummay be analyzed by this test method.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 concer
4、ns, if any, associated with 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:2D 1129 Terminology Relating to WaterD 119
5、3 Specification for Reagent WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 5810 Guide for Spiking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsf
6、or Standard Test Methods for Water Analysis3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D 1129.4. Summary of Test Method4.1 This test method is dependent on the fact that metallicelements, in the ground state, will absorb light of the samewavele
7、ngth they emit when excited. When radiation from agiven 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 in the flame. A hollow cathodelamp whose cath
8、ode is made of the element to be determinedprovides the radiation. The metal atoms3to be measured areplaced in the beam of radiation by aspirating the specimen intoan oxidant-fuel flame. A monochromator isolates the charac-teristic radiation from the hollow cathode lamp and a photo-sensitive device
9、measures the attenuated transmitted radiation.4.2 Since the variable and sometimes high concentrations ofmatrix materials in the waters and brines affect absorptiondifferently, it is difficult to prepare standards sufficiently similarto the waters and brines. To overcome this difficulty, themethod o
10、f additions is used in which three identical samplesare prepared and varying amounts of a standard added to twoof them. The three samples are then aspirated, the concentra-tion readings recorded, and the original sample concentrationcalculated.5. Significance and Use5.1 This test method4can be used
11、to determine strontiumions in brackish water, seawater, and brines.6. Interferences6.1 The chemical suppression caused by silicon, aluminum,and phosphate is controlled by adding lanthanum. The lantha-num also controls ionization interference.7. Apparatus7.1 Atomic Absorption SpectrophotometerThe ins
12、trumentshall consist of atomizer and burner, suitable pressure-regulating devices capable of maintaining constant oxidant andfuel pressure for the duration of the test, a hollow cathode lampfor each metal to be tested, an optical system capable of1This test method is under the jurisdiction of ASTM C
13、ommittee D19 on Waterand is the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved Nov. 15, 2008. Published November 2008. Originallyapproved in 1974. Last previous edition approved in 2008 as D 3352 08.2For referenced ASTM standards, visit the AS
14、TM 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.3For additional information on atomic absorption, see the following references:Angino, E. E., and Billing
15、s, G. K., Atomic Absorption Spectrophotometry inGeology, Elsevier Publishing Co., New York, N.Y., 1967. Dean, J. A., and Rains, T.C., Editors, Flame Emission and Atomic Absorption Spectrometry Vol 1 Theory,Marcel Dekker, New York, NY, 1969.4Additional information is contained in the following refere
16、nces: Fletcher, G. F.,and Collins, A. G., “Atomic Absorption Methods of Analysis of Oilfield Brines:Barium, Calcium, Copper, Iron, Lead, Lithium, Magnesium, Manganese, Potassium,Sodium, Strontium, and Zinc,” U.S. Bureau of Mines, Report of Investigations7861, 1974, 14 pp. Collins, A. G., Geochemistr
17、y of Oilfield Waters, ElsevierPublishing Co., Amsterdam. The Netherlands, 1975.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.isolating the desired line of radiation, an adjustable slit, aphotomultiplier tube or other photosensitive
18、 device as a lightmeasuring and amplifying device, and a read-out mechanismfor indicating the amount of absorbed radiation.7.1.1 Multi-Element Hollow Cathode Lamps are availableand have been found satisfactory.7.2 Pressure-Reducing ValvesThe supplies of fuel andoxidant shall be maintained at pressur
19、es somewhat 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
20、-tee onAnalytical Reagents of theAmerican Chemical Society,5where 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 Purity of WaterUnless
21、 otherwise indicated, referenceto water shall be understood to mean reagent water conformingto Specification D 1193, Type I. Other reagent water types maybe used provided it is first ascertained that the water is ofsufficiently high purity to permit its use without adverselyaffecting the precision a
22、nd bias of the test method. Type IIIwater was specified at the time of round robin testing of thistest method.8.3 Lanthanum Solution (5 % La)Wet 58.65 g of lantha-num oxide (La2O3) with water. Add 250 mL of concentratedhydrochloric acid (sp gr 1.19) very slowly until the material isdissolved. Dilute
23、 solution to 1 litre with water.8.4 Strontium Solution, Standard (1 mL = 1 mg Sr)Dissolve 2.415 g of strontium nitrate Sr(NO3)2in10mLofconcentrated hydrochloric acid (sp gr 1.19) and about 700 mLof water. Dilute solution to 1 Lwith water. One millilitre of thissolution contains 1 mg of strontium. Al
24、ternatively, certifiedstrontium stock solutions are commercially available throughchemical supply vendors and may be used.8.5 Oxidant, for Atomic Absorption Spectrophotometer:8.5.1 Air, which has been cleaned and dried through asuitable filter to remove oil, water, and other foreign sub-stances, is
25、the usual oxidant.8.5.2 Nitrous Oxide may be required as an oxidant forrefractory-type metals.8.6 Fuel, for Atomic Absorption Spectrophotometer:8.6.1 AcetyleneStandard, commercially available acety-lene is the usual fuel. Acetone, always present in acetylenecylinders, can be prevented from entering
26、and damaging theburner head by replacing a cylinder which only has 100 psig ofacetylene remaining.9. Sampling9.1 Collect the sample in accordance with Practices D 3370.10. Procedure10.1 Strontium is determined at the 460.7-nm wavelengthwith an air-acetylene flame.10.2 Preliminary CalibrationUsing mi
27、cropipets preparestandard strontium solutions containing 1 to 10 mg/L ofstrontium using the standard strontium solution and 50-mLvolumetric flasks. Before making up to volume, add to each ofthese and to a blank, 5 mL of the lanthanum solution. Aspiratethese standards and the blank (for background se
28、tting) andadjust the curvature controls, if necessary, to obtain a linearrelationship between absorbance and the actual concentrationof the standards.10.3 Transfer an aliquot of water or brine (previouslyfiltered through a 0.45-m filter) to a 50-mL volumetric flask.The specific gravity of the water
29、or brine can be used toestimate the strontium content of the sample and, thereby, serveas a basis for selecting the aliquot size that will contain about0.1 mg of strontium. Fig. 1 shows the relationship betweenstrontium concentration and specific gravity for some oilfieldbrines from the Smackover fo
30、rmation. The concentrations ofstrontium in the Smackover brines will not necessarily corre-late with the concentrations found in other formations. There-fore, the user of this test method may find it necessary to drawa similar curve for brine samples taken from other formations.Add 5 mL of the lanth
31、anum stock solution, dilute to volume,and aspirate. Calculate the approximate sample concentrationfrom the preliminary calibration readings, and determine thealiquot size that will contain about 0.1 mg of strontium.10.4 Transfer equal aliquots containing about 0.1 mg ofstrontium to three 50-mL volum
32、etric flasks. Add no strontiumstandard to the first flask. With a micropipet add 0.1 mg to thesecond and 0.2 mg to the third.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Ch
33、emical 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.TABLE 1 Compositions of Artificial Brine SamplesSample No.g/L1 234Sr 0.060 0.100 1.600 2.100
34、NaCl 24.0 170.0 80.0 200.0KCl 0.5 2.0 1.5 3.0KBr 1.0 2.0 2.0 2.0KI 0.1 0.5 0.5 1.0CaCl21.5 3.0 2.0 5.0MgCl24.5 5.0 2.0 1.0BaCl20.05 1.0 0.5 0.5TABLE 2 Determination of Precision and Bias of Strontium IonAmountAdded,mg/LAmountFound,mg/LSOST6 BiasStatisticallySignificant(95 %ConfidenceLevel)60 63.48 2
35、.96 8.49 + 5.8 yes100 99.5 4.12 11.84 0.5 no1600 1665.6 54.87 157.3 + 4.1 no2100 2167.2 71.12 203.9 + 3.2 noD 3352 08a210.5 Add 5 mL of the lanthanum solution to each of thethree flasks and dilute to volume. Aspirate and record theabsorbance readings for each sample.11. Calculation11.1 Calculate the
36、 concentration of strontium ion in theoriginal sample in milligrams per litre as follows:Strontium concentration, mg/L 5V1As3 Cstd!V2Astd2 As!where:V1= volume of the diluted samples, mL,V2= volume of the original sample, mL,As= absorbance of dilute sample,Astd= absorbance of one of the standard addi
37、tions, andCstd= concentration of the same standard addition as Astd,mg/L.Since there are two standard additions, calculate for each andaverage the two results.12. Precision and Bias612.1 The precision of the test method within its designatedrange may be expressed as follows:St5 0.0929X 1 2.596So5 0.
38、0324X 1 0.9016Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D191022.FIG. 1 Relationship of the Concentration of Strontium in Some Oilfield Brines to Specific GravityD 3352 08a3whereSt= overall precision,So= single-operator pre
39、cision, andX = concentration of strontium determined, mg/L.12.2 The bias of the test method determined from recoveriesof known amounts of strontium in a series of preparedstandards are given in Table 2.NOTE 1The above precision and bias estimates are based on aninterlaboratory study on four artifici
40、al brine samples containing variousamounts of strontium and interfering ions as shown in Table 1. Oneanalyst in each of three laboratories and two analysts in each of sixlaboratories performed duplicate determinations on each of two days.Practice D 2777 was used in developing these precision and bia
41、s esti-mates.12.3 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 ofD 2777 06, these precision and bias data do meet existingrequirements for interlaboratory studies of Committee D19 testm
42、ethods.13. Quality Control13.1 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 strontium.13.2 Calibration and Calibration Verification13.2.1 Analy
43、ze at least three working standards containingconcentrations of strontium that bracket the expected sampleconcentration, prior to analysis of samples, to calibrate theinstrument.13.2.2 Verify instrument calibration after standardization byanalyzing a standard at the concentration of one of thecalibr
44、ation standards. The absorbance shall fall within4%ofthe absorbance from the calibration. Alternately, the concen-tration of a mid-range standard should fall within 615 % of theknown concentration.13.2.3 If calibration cannot be verified, recalibrate theinstrument.13.3 Initial Demonstration of Labor
45、atory Capability13.3.1 If a laboratory has not performed the test before, or ifthere has been a major change in the measurement system, forexample, new analyst, new instrument, etc., a precision andbias study must be performed to demonstrate laboratorycapability.13.3.2 Analyze seven replicates of a
46、standard solutionprepared from an Independent Reference Material containing amidrange concentration of strontium. The matrix and chemis-try of the solution should be equivalent to the solution used inthe collaborative study. Each replicate must be taken throughthe complete analytical test method inc
47、luding any samplepreservation and pretreatment steps.13.3.3 Calculate the mean and standard deviation of theseven values and compare to the acceptable ranges of bias in12.1. This study should be repeated until the recoveries arewithin the limits given in 12.1. If a concentration other than therecomm
48、ended concentration is used, refer to Practice D 5847for information on applying the F test and t test in evaluatingthe acceptability of the mean and standard deviation.13.4 Laboratory Control Sample (LCS)13.4.1 To ensure that the test method is in control, analyzea LCS containing a mid-range concen
49、tration of strontium witheach batch or ten samples. If large numbers of samples areanalyzed in the batch, analyze the LCS after every ten samples.The LCS must be taken through all of the steps of the analyticalmethod including sample preservation and pretreatment. Theresult obtained for the LCS shall fall within 615 % of theknown concentration.13.4.2 If the result is not within these limits, analysis ofsamples is halted until the problem is corrected, and either allthe samples in the batch must be reanalyzed, or the results mustbe qualified with an indication
