1、Designation: D 4130 03Standard 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 (e) 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 su
3、ccessfully 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.Aconcentrat
4、ion 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 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibil
5、ity 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:D 516 Test Methods for Sulfate Ion in Water2D 1129 Terminology Relating to Water2D 1192 Specificati
6、on for Equipment for Sampling Waterand Steam in Closed Conduits2D 1193 Specification for Reagent Water2D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D-19 on Water2D 3370 Practices for Sampling Water from Closed Con-duits2D 5810 Guide for Spiking into Aqueo
7、us Samples2D 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3E 275 Practice for Describing and Measuring Performancesof Ultraviolet, Visible, and Near Infrared Spectrophotom-eters43. Terminology3.1 DefinitionsFor definitions of terms used in this
8、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 adjust the ionic stren
9、gth 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 theconcentration of the major ion
10、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 is important in iden
11、tifying 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 barium sulfate(BaSO4).1T
12、his 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 June 10, 2003. Published July 2003. Originallyapproved in 1982. Last previous edition approved in 1999 as D 41309
13、9.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 11.02.4Annual Book of ASTM Standards, Vol 03.06.1*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, Unite
14、d States.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.Filter photometers, spectrophotometers, and photomet
15、ric 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 conform to the specifications of the commit-tee on Analytical Reagents of
16、 the American Chemical Society,where such specifications are available.5Other grades may beused, providing 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 otherwise indicated, refere
17、nceto 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 and bias of the test method.
18、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 to 70 mesh.8.4 Glycerin-Acid SolutionMix 250 mL of glycerin and50 mL o
19、f 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 water.8.6 Sulfate Solution, Standard (1 mL = 1.00 mg SO4=)Dissolve 1.479 g
20、 of anhydrous sodium sulfate, (Na2SO4), inwater and dilute to 1 L in a volumetric flask.9. Sampling9.1 Collect the sample in accordance with the applicableASTM standard as follows: Specification D 1192 or PracticesD 3370.9.2 Preserve the samples with high purity hydrochloric acidto a pH of two or le
21、ss 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 solution (1 mL = 1.00 mgSO4=) to separate 100 mL graduated mixing cylinders. Add5.0 mL of glycerin-acid solution and 40.0 mL of sodiumchl
22、oride solution (5 mol) to each of the cylinders and dilute to100 mLwith water.Adjust the temperature of these solutions to25 6 2C. These solutions will contain 1.0, 2.0, 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 acalibra
23、tion curve showing sulfate ion content in milligrams onthe linear axis with the corresponding percent transmittance(%T) reading of the photometer on the logarithmic axis of aone cycle semilogarithmic graph paper (Note 2).NOTE 2The plot of concentration versus %T is not linear but shows aslight s cur
24、vature. 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 solut
25、ions 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 volume of filtered sample not to exceed 50 mLand 10 mg SO42-into a 100-mLgraduated mixing cylinder.Theionic strength (IS) of the sam
26、ple 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 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,
27、 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 and measurement of the turbidity must be within 2C ofthe temperature of the standards when the calibration was performed. Ahigher t
28、emperature 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 thephotometer to 100 % T (transmittance) with the wavelength setat 425 nm or blue filter in place.11.7 Add
29、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 15times.NOTE 4It is important the mixing be performed at a constant rate andduplicated in all determinations.11.8 Just before 5 min
30、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 greater than 80 % or less than 30 % T, the determinationwith a smaller or larger sample volume providing the restric-tions in step 11.2 a
31、re 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 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 finalr
32、esults.5Reagent Chemicals, American Chemical Society Specifications, Am. ChemicalSoc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Society, see Analar Standards for Laboratory Chemicals, BDHLtd., Poole, Dorset, U.K., and the United States Pharmacopei
33、a.D 4130 03212. Calculation12.1 Convert the photometer reading to mg SO42-by refer-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 Bias613.1 The over
34、all and single-operator precision of this testmethod within its designated range for 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 notappl
35、y. 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 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 ofco
36、llaborative testing. Under the allowances made in 1.4 of D2777-98, these precision and bias data do meet existingrequirements for interlaboratory studies of Committee D19 testmethods.NOTE 6The precision and bias estimates are based on an interlabo-ratory study on three synthetic brine samples contai
37、ning various amountsof sulfate and other inorganic compounds as shown in Table 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 C
38、ontrol14.1 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 sulfate.14.2 Calibration and Calibration Verification14.2.1 Analyze at least three work
39、ing standards containingconcentrations of sulfate that bracket the expected 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. Alternate
40、ly, the concentration of a mid-range standard should fall within 615% of the 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 maj
41、or change in the measurement system, forexample, new analyst, new instrument, 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 concentratio
42、n of sulfate. The matrix and chemistryof the solution should be equivalent 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. The replicates may be inter-spersed with sampl
43、es.14.3.3 Calculate the mean and standard deviation of theseven values and compare to the acceptable ranges of bias in13.1. 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 D58
44、47for information on applying the F test and t test in evaluatingthe acceptability of the mean and standard deviation.14.4 Laboratory 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. I
45、f 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.14.4.2
46、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 that they do not fall within theperformance criteria of the test method.14.5 Method Bla
47、nk14.5.1 Analyze a reagent water test blank with each batch.The concentration of sulfate found in the blank should be lessthan 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, an
48、d a blankshows no contamination at or above this level, or the resultsmust be qualified with an indication that they do not fall withinthe performance criteria of the test method.14.6 Matrix Spike (MS)6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requestin
49、g 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 0.1289 0.0603D 4130 03314.6.1 To check for interferences in the specific matrixbeing tested, perform a MS on at least one sample from eachbatch by spiking an aliquot of the sample w
