1、Designation: D 4130 08Standard Test Method forSulfate Ion in Brackish Water, Seawater, and Brines1This standard is issued under the fixed designation D 4130; 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. Scope1.1 This test method covers the turbidimetric determinationof sulfate ion in brackish water, seawater, and brines. It hasbeen used succ
3、essfully 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.Aconcentratio
4、n 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 D 516.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5
5、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 determine the applica-bility of regulatory limitations prior to use.2. Referenced Docum
6、ents2.1 ASTM Standards:2D 516 Test Method for Sulfate Ion in WaterD 1129 Terminology Relating to WaterD 1193 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 Condu
7、itsD 5810 Guide for Spiking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE 275 Practice for Describing and Measuring Performanceof Ultraviolet and Visible Spectrophotometers3. Terminology3.1 Definitions: For definitions of
8、terms used in this testmethod, refer to Terminology D 1129.4. 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 stabilize the suspension. A calculated volume ofa NaCl solution is added to adj
9、ust 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.NOTE 1The ionic strength (IS) of the sample is calculated from theconcentratio
10、n 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. Significance and Use5.1 The determination of sulfate and other dissolved con-stituents i
11、s 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 compensated for in the procedureinterfere with the measurement of suspended bariu
12、m sulfate(BaSO4).7. Apparatus7.1 PhotometerA filter photometer or a spectrophotom-eter for measurements between 400 to 450 nm, the preferablewavelength being 425 nm. The cell for the instrument musthave a light path of 20 6 2 mm and hold a volume of 25 mL.1This test method is under the jurisdiction
13、of ASTM Committee 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 1982. Last previous edition approved in 2003 as D 4130 03.2For referenced ASTM standards, vis
14、it 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, PO Box C700, West Conshohocken, PA 19428-2
15、959, United States.Filter photometers, spectrophotometers, and photometric prac-tices prescribed in this test method shall conform to PracticeE 275.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall co
16、nform 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 that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of
17、the determination.8.2 Purity of WaterUnless 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
18、 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 test methodshall be sulfate-free.8.3 Barium ChlorideCrystals of barium chloride(BaCL22H2O) screened to 20
19、 to 70 mesh.8.4 Glycerin-Acid SolutionMix 250 mL of glycerin and50 mL of hydrochloric acid (HCl, sp gr 1.19) and dilute to 500mL with water.8.5 Sodium Chloride Solution (5 mol)Dissolve 584.4 g ofsodium chloride (NaCl) containing less than 0.001% SO4inabout 1800 mL of water and dilute to 2 L with wat
20、er.8.6 Sulfate Solution, Standard (1 mL = 1.00 mg SO4=)Dissolve 1.479 g of anhydrous sodium sulfate, (Na2SO4), inwater and dilute to 1 L in a volumetric flask. Alternatively,certified sulfate stock solutions are commercially availablethrough chemical supply vendors and may be used.9. Sampling9.1 Col
21、lect the sample in accordance with Practices D 3370.9.2 Preserve the samples with high purity hydrochloric acidto a pH of two or less immediately at the time of collection (2mL/L).10. Calibration10.1 Prepare standards by adding 1.0, 2.0, 3.0, 4.0, 5.0, 6.0,8.0, and 10.0 mL of sulfate standard soluti
22、on (1 mL = 1.00 mgSO4=) to separate 100 mLgraduated mixing cylinders.Add 5.0mL of glycerin-acid solution and 40.0 mL of sodium chloridesolution (5 mol) to each of the cylinders and dilute to 100 mLwith water. Adjust the temperature of these solutions to 25 62C. These solutions will contain 1.0, 2.0,
23、 3.0, 4.0, 5.0, 6.0,8.0, and 10.0 mg of sulfate ion, respectively.10.2 Follow the procedure as given in 11.6-11.8. Prepare acalibration curve showing sulfate ion content in milligrams onthe linear axis with the corresponding percent transmittance(%T) reading of the photometer on the logarithmic axis
24、 of aone cycle semilogarithmic graph paper (Note 2).NOTE 2The plot of concentration versus %T is not linear but shows aslight s curvature. 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
25、 any other alterations of the instrument orreagents are made. Check the curve with each series of tests by runningtwo or more solutions of known sulfate concentrations.11. Procedure11.1 Filter the sample through a 0.45-m membrane filter.This is necessary to remove nucleating particles.11.2 Pipet a v
26、olume of filtered sample not to exceed 50 mLand 10 mg SO42-into a 100-mLgraduated mixing cylinder.Theionic strength (IS) of the sample when diluted to 100 must notexceed 2.00 mol/L.11.3 Add 5 mL of glycerin-acid solution.11.4 Add by a graduated pipet or a buret a volume ofsodium chloride solution (5
27、 mol) calculated as follows:mLNaCl 5 200 2 V 3 IS!/5V = volume of sample, andIS = ionic strength of sample as calculated in Note 1, 4.1.11.5 Dilute with water to 100 mL, mix well, and adjust thetemperature to 25 6 2C.NOTE 3The temperature of the solution in the mixing cylinder duringthe development
28、and measurement of the turbidity must be within 2C ofthe temperature of the standards when the calibration was performed. 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 th
29、e cell compartment. Set thephotometer 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 to the 75 mLremaining in the mixing cylinder, stopper, set a timer for 5 min,and mix for 30 s by inverting and righting the cylinder 1
30、5times.NOTE 4It is important the mixing be performed at a constant rate andduplicated in all determinations.11.8 Just before 5 min has expired, check the blank setting.Adjust to 100 %T if drifting has occurred. Replace the blankwith the sample cell and measure turbidity at 5 min. If the % Tis greate
31、r than 80 % or less than 30 % T, the determinationwith a smaller or larger sample volume providing the restric-tions in step 11.2 are not violated.NOTE 5The most reproducible section of the calibration curve is from80 to 30 % T. Very low concentrations of sulfate ion can be determined byadding 3 mL
32、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.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by th
33、e 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.D413008212. Calculation12.1 Convert the photometer reading to mg SO42-by refer-
34、ring to the calibration curve. Calculate the sulfate ion concen-tration as follows:Sulfate, mg/L 5 W 3 1000/VW = 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 fo
35、r brackish water, seawa-ter, and brines varies with the quantity tested in accordancewith 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 wat
36、ers of untested matrices.13.3 The bias of the method determined in synthetic brine ispresented in Table 1.13.4 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 ofPractice D 2777 06, these p
37、recision and bias data do meetexisting requirements for interlaboratory studies of CommitteeD19 test methods.NOTE 6The 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 T
38、able 2. Oneanalyst in five laboratories and two analysts in each of two laboratoriesperformed single determinations on each of three days. Practice D 2777,was used in developing these precision and bias estimates.14. Quality Control14.1 In order to be certain that analytical values obtainedusing the
39、se test methods are valid and accurate within theconfidence limits of the test, the following QC procedures mustbe followed when analyzing sulfate.14.2 Calibration and Calibration Verification14.2.1 Analyze at least three working standards containingconcentrations of sulfate that bracket the expecte
40、d sampleconcentration prior to analysis of samples to calibrate theinstrument.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 t
41、he known concen-tration.14.2.3 If calibration cannot be verified, recalibrate theinstrument.14.3 Initial Demonstration of Laboratory Capability14.3.1 If a laboratory has not performed the test before, or ifthere has been a major change in the measurement system, forexample, new analyst, new instrume
42、nt, etc., a precision andbias study must be performed to demonstrate 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
43、 to the solution used in thecollaborative study. Each replicate must be taken through thecomplete analytical test method including any sample preser-vation and pretreatment steps.14.3.3 Calculate the mean and standard deviation of theseven values and compare to the acceptable ranges of bias in13.1.
44、This study should be repeated until the recoveries arewithin the limits given in 13.1. If a concentration other than therecommended concentration is used, refer to Practice D5847for information on applying the F test and t test in evaluatingthe acceptability of the mean and standard deviation.14.4 L
45、aboratory Control Sample (LCS)14.4.1 To ensure that the test method is in control, analyzea LCS containing a mid-range concentration of sulfate 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 a
46、ll of the steps of the analyticalmethod including sample preservation and pretreatment. Theresult obtained for the LCS shall fall within 615 % of theknown concentration.14.4.2 If the result is not within these limits, analysis ofsamples is halted until the problem is corrected, and either allthe sam
47、ples in the batch must be reanalyzed, or the results mustbe qualified with an indication that they do not fall within theperformance criteria of the test method.14.5 Method Blank14.5.1 Analyze a reagent water test blank with each batch.The concentration of sulfate found in the blank should be lessth
48、an 0.5 times the lowest calibration standard. If the concen-tration of sulfate is found above this level, analysis of samplesis halted until the contamination is eliminated, and a blankshows no contamination at or above this level, or the resultsmust be qualified with an indication that they do not
49、fall withinthe performance criteria of the test method.14.6 Matrix Spike (MS)4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D191077.TABLE 1 Determination of Precision and BiasAmountAdded,mg/LAmountFound,mg/LSTSO% BiasStatisticallySignificant (95 %confidence level)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 Brine SamplesSample No.g/L123NaCl 47.74 61.04 95.33CaCl227.22 40.85 54.47MgCl23.84 7.68 7.71SO4=0.0863 0
