1、Designation: D4130 15Standard Test Method forSulfate Ion in Brackish Water, Seawater, and Brines1This standard is issued under the fixed designation D4130; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、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 turbidimetric determinationof sulfate ion in brackish water, seawater, and brines. It hasbeen used succe
3、ssfully with synthetic brine grade waters;however, it is the users responsibility to ensure the validity ofthis test method to other matrices.1.2 This test method is applicable to waters having an ionicstrength greater than 0.65 mol/Land a sulfate ion concentrationgreater than 25 mg/L.Aconcentration
4、 less than 25 mg/Lsulfatecan be determined by using a standard addition method.1.3 For brines having an ionic strength of less than 0.65mol/L, refer to Test Methods D516.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 Th
5、is 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 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documen
6、ts2.1 ASTM Standards:2D516 Test Method for Sulfate Ion in WaterD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD581
7、0 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible SpectrophotometersE2251 Specification for Liquid-in-Glass ASTM Thermom-eters w
8、ith Low-Hazard Precision Liquids3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D1129.4. Summary of Test Method4.1 A sulfate ion is converted to a barium sulfate suspendedunder controlled conditions. A glycerin-acid solution is addedto acidify and
9、stabilize the suspension. A calculated volume ofa NaCl solution is added to adjust the ionic strength to a setvalue of 2 mol/L (Note 1). The turbidity resulting uponaddition of barium chloride is determined by a photoelectriccolorimeter and compared to a curve prepared from standardsulfate solutions
10、.NOTE 1The ionic strength (IS) of the sample is calculated from theconcentration of the major ion constituents (Na+,Ca2+,Mg2+,Cl), (K+and Sr2+if their concentration exceeds 2000 mg/L) as follows:where:IS, mol/L = 1/2 CiZi2,Ci= g/L ion i/molecular weight ion, i, andZi= valence of ion i.5. Significanc
11、e and Use5.1 The determination of sulfate and other dissolved con-stituents is important in identifying the source of brinesproduced during the drilling and production phases of crude oilor natural gas.6. Interferences6.1 Suspended matter in the sample must be removed. Darkcolors that cannot be comp
12、ensated for in the procedureinterfere with the measurement of suspended barium sulfate(BaSO4).7. Apparatus7.1 PhotometerAfilter photometer or a spectrophotometerfor measurements between 400 to 450 nm, the preferablewavelength being 425 nm. The cell for the instrument musthave a light path of 20 6 2
13、mm and hold a volume of 25 mL.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 Feb. 1, 2015. Published April 2015. Originallyapproved in 1982. Last previous edi
14、tion approved in 2008 as D4130 08. DOI:10.1520/D4130-15.2For 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.*A Su
15、mmary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Filter photometers, spectrophotometers, and photometric prac-tices prescribed in this test method shall conform to PracticeE27
16、5.7.2 ThermometerAn ASTM Gravity Thermometer havinga range from 20 to +102C (or 5 to +215F), as specified,and conforming to the requirements for Thermometer ASTM12C (or ASTM 12F), respectively, as prescribed in Specifica-tion E2251.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemica
17、ls shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, providing it is first ascertained
18、that 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 Specification D1193, D1129, Type I. Other reagent watertypes may
19、 be used provided it is first ascertained that the wateris of sufficiently high purity to permit its use without adverselyaffecting the precision and bias of the test method. Type IIIwater was specified at the time of round robin testing of thistest method. In addition, reagent water used for this t
20、est methodshall be sulfate-free.8.3 Barium ChlorideCrystals of barium chloride(BaCL22H2O) screened to 20 to 70 mesh.8.4 Filter PaperPurchase suitable filter paper. Typicallythe filter papers have a pore size of 0.45-m membrane.Material such as fine-textured, acid-washed, ashless paper, orglass fiber
21、 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.8.5 Glycerin-Acid SolutionMix 250 mLof glycerin and 50mLof hydrochloric acid (HCl, sp gr 1.19) and dilute to 500 mLwith water.
22、8.6 Sodium Chloride Solution (5 mol/L)Dissolve 584.4 gof sodium chloride (NaCl) containing less than 0.001% SO4inabout 1800 mL of water and dilute to 2 L with water.8.7 Sulfate Solution, Standard (1 mL = 1.00 mg SO4=)Dissolve 1.479 g of anhydrous sodium sulfate, (Na2SO4), inwater and dilute to 1 L i
23、n a volumetric flask. Alternatively,certified sulfate stock solutions of appropriate known purity arecommercially available through chemical supply vendors andmay be used.9. Sampling9.1 Collect the sample in accordance with Practices D3370.9.2 Preserve the samples with high purity hydrochloric acidt
24、o a pH of two or less immediately at the time of collection (2mL/L).NOTE 2Alternatively, the pH may be adjusted in the laboratory if thesample is returned within 14 days. However, acid must be added at least24 hours before analysis to dissolve any metals that adsorb to the containerwalls. This could
25、 reduce hazards of working with acids in the field whenappropriate.10. Calibration10.1 Analyze at least three working standards containingconcentrations of sulfate that bracket the expected sampleconcentration prior to analysis of samples to calibrate theinstrument. Prepare standards by adding 1.0,
26、2.0, 3.0, 4.0, 5.0,6.0, 8.0, and 10.0 mL of sulfate standard (8.7) solution (1mL = 1.00 mg SO4=) to separate 100 mL graduated mixingcylinders. Add 5.0 mL of glycerin-acid (8.5) solution and 40.0mL of sodium chloride (8.6) solution (5 mol/L) to each of thecylinders and dilute to 100 mL with water.Adj
27、ust the tempera-ture of these solutions to 25 6 2C. These solutions willcontain 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 8.0, and 10.0 mg of sulfateion, respectively.10.2 Follow the procedure as given in 11.6 11.8. Readdirectly in concentration if this capability is provided with theinstrument. Alternatively,
28、prepare a semi-log plot and a cali-bration curve showing sulfate ion content in milligrams on thelinear axis with the corresponding percent transmittance (%T)reading of the photometer on the logarithmic axis (Note 3).NOTE 3The plot of concentration versus %T is not linear but shows aslight s curvatu
29、re. A separate calibration curve must be prepared for eachphotometer and a new curve must be prepared if it is necessary to changethe photo cell, lamp, filter, or if any other alterations of the instrument orreagents are made. Check the curve with each series of tests by runningtwo or more solutions
30、 of known sulfate concentrations.11. Procedure11.1 Filter the sample through a 0.45-m membrane filter(8.4). This is necessary to remove nucleating particles.11.2 Pipet a volume of filtered sample not to exceed 50 mLand 10 mg SO42-into a 100-mLgraduated mixing cylinder.Theionic strength (IS) of the s
31、ample when diluted to 100 must notexceed 2.00 mol/L.11.3 Add 5 mL of glycerin-acid (8.5) solution.11.4 Add by a graduated pipet or a buret a volume ofsodium chloride (8.6) solution (5 mol/L) calculated as follows:mL NaCl 5 2002 V 3 IS!5V = volume of sample, andIS = ionic strength of sample as calcul
32、ated in Note 1, 4.1.11.5 Dilute with water to 100 mL, mix well, and adjust thetemperature to 25 6 2C.NOTE 4The temperature of the solution in the mixing cylinder duringthe development and measurement of the turbidity must be within 2C ofthe temperature of the standards when the calibration was perfo
33、rmed. Ahigher temperature will result in a positive error, a lower temperature in anegative error.11.6 Pipet a 25-mL aliquot of the sample solution into asample cell and place it in the cell compartment. Set the3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, W
34、ashington, 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.D4130
35、152photometer to 100 % T (transmittance) with the wavelength setat 425 nm or blue filter in place.11.7 Add 0.3 6 0.01 g of BaCl22H2O crystals (8.3)tothe75 mLremaining in the mixing cylinder, stopper, set a timer for5 min, and mix for 30 s by inverting and righting the cylinder15 times.NOTE 5It is im
36、portant the mixing be performed at a constant rate andduplicated in all determinations.11.8 Just before 5 min has expired, check the blank setting(sample from 11.6 without the BaCl2). Adjust to 100 %T ifdrifting has occurred. Replace the blank with the sample celland measure turbidity at 5 min. If t
37、he % T is greater than80 % or less than 30 % T, the determination with a smaller orlarger sample volume providing the restrictions in step 11.2 arenot violated.NOTE 6The most reproducible section of the calibration curve is from80 to 30 % T. Very low concentrations of sulfate ion can be determined b
38、yadding 3 mL of sulfate standard (1 mL = 1.00 mg SO42-) before dilutingto 100 mL in step 11.5 and then subtracting the 3 mg SO42-from the finalresults.12. Calculation12.1 Convert the photometer reading to mg SO42-byreferring to the calibration curve. Calculate the sulfate ionconcentration as follows
39、:Sulfate, mg/L 5 W 31000/V1000 = 1000 mL/L,W = milligram SO42-from the calibration curve, andV = sample volume, mL.13. Precision and Bias413.1 The overall and single-operator precision of this testmethod within its designated range for brackish water,seawater, and brines varies with the quantity tes
40、ted in accor-dance with Table 1.13.2 These collaborative test data were obtained on syn-thetic brine waters. For other matrixes, these data may notapply. It is the users responsibility to ensure the validity of thistest method for waters of untested matrices.13.3 The bias of the method determined in
41、 synthetic brine ispresented in Table 1.13.4 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 D2777 13, these precision and bias data do meetexisting requirements for interlaborat
42、ory studies of CommitteeD19 test methods.NOTE 7The precision and bias estimates are based on an interlabo-ratory study on three synthetic brine samples containing various amountsof sulfate and other inorganic compounds as shown in Table 2. Oneanalyst in five laboratories and two analysts in each of
43、two laboratoriesperformed single determinations on each of three days. Practice D2777,was used in developing these precision and bias estimates.14. Quality Control14.1 In order to be certain that analytical values obtainedusing these test methods are valid and accurate within theconfidence limits of
44、 the test, the following QC procedures mustbe followed when analyzing sulfate.14.2 Calibration and Calibration Verification:14.2.1 Analyze at least three working standards containingconcentrations of sulfate that bracket the expected sampleconcentration prior to analysis of samples to calibrate thei
45、nstrument (see 10.1).14.2.2 Verify instrument calibration after standardization byanalyzing a standard at the concentration of one of thecalibration standards. Alternately, the concentration of a mid-range standard should fall within 615 % of the knownconcentration.14.2.3 If calibration cannot be ve
46、rified, recalibrate theinstrument.14.2.4 It is recommended to analyze a continuing calibra-tion blank (CCB) and continuing calibration verification(CCV) at a 10 % frequency. The results should fall within theexpected precision of the method or 615 % of the knownconcentration. Analyze a calibration b
47、lank to verify systemcleanliness.14.3 Initial Demonstration of Laboratory Capability:14.3.1 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 d
48、emonstrate laboratorycapability.14.3.2 Analyze seven replicates of a standard solutionprepared from an Independent Reference Material containing amid-range concentration of sulfate. The matrix and chemistryof the solution should be equivalent to the solution used in thecollaborative study. Each repl
49、icate must be taken through thecomplete analytical test method including any sample preser-vation and pretreatment steps.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D19-1077. ContactASTM CustomerService at serviceastm.org.TABLE 1 Determination of Precision and BiasAmountAdded,mg/LAmountFound,mg/LSTSO% BiasStatisticallySignificant(95 %confidencelevel)60.3 61.7 9.35 2.47 +2.32 no86.3 83.9 6.98 2.45 2.78 no128.9 126.1 6.15 2.67 2.17 noTABLE 2 Composition of Synthetic
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