1、Designation: D7319 11Standard Test Method forDetermination of Existent and Potential Sulfate andInorganic Chloride in Fuel Ethanol by Direct InjectionSuppressed Ion Chromatography1This standard is issued under the fixed designation D7319; the number immediately following the designation indicates th
2、e year oforiginal adoption or, 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 a direct injection ion ch
3、romato-graphic procedure for determining existent and potential inor-ganic sulfate and total inorganic chloride content in hydrousand anhydrous denatured ethanol to be used in motor fuelapplications. It is intended for the analysis of ethanol samplescontaining between 1.020 mg/kg of existent or pote
4、ntialinorganic sulfate and 1.050 mg/kg of inorganic chloride.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is the
5、responsibility 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. Material SafetyData Sheets are available for reagents and materials. Reviewthem for hazards prior to usage.2. Referenced Document
6、s2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4052 Test Method for Density, Relative Density, and APIGravity of Liquids by Digital Density MeterD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD5
7、827 Test Method for Analysis of Engine Coolant forChloride and Other Anions by Ion ChromatographyD6299 Practice for Applying Statistical Quality Assuranceand Control Charting Techniques to Evaluate AnalyticalMeasurement System PerformanceD6792 Practice for Quality System in Petroleum Productsand Lub
8、ricants Testing LaboratoriesD7318 Test Method for Existent Inorganic Sulfate in Etha-nol by Potentiometric TitrationD7328 Test Method for Determination of Existent andPotential Inorganic Sulfate and Total Inorganic Chloride inFuel Ethanol by Ion Chromatography Using AqueousSample Injection2.2 Europe
9、an Norm Standards:3EN 15492 Ethanol as a blending component for petrol -Determination of inorganic chloride and sulfate content -Ion chromatographic method3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 existent inorganic sulfate, ninorganic sulfate speciesactually present in
10、the sample at the time of analysis with nooxidation treatment.3.1.2 inorganic chloride, nchloride present as hydrochlo-ric acid, ionic salts of this acid, or mixtures of these.3.1.3 inorganic sulfate, nsulfate (SO4-2) species presentas sulfuric acid, ionic salts of this acid, or mixtures of these.3.
11、1.4 potential sulfate, ninorganic sulfate species presentafter the sample has been reacted with an oxidizing agent.4. Summary of Test Method4.1 For existent inorganic sulfate and total chloride, a smallvolume of an ethanol sample is directly injected into a suitablyconfigured ion chromatograph in ac
12、cordance with manufactur-ers recommendations for this test method. For potentialsulfate, 0.5 mL of 30 % hydrogen peroxide solution is added to9.5 mL of the ethanol sample, and then injected into the ionchromatograph. Ions are separated based on their affinity forexchange sites of the resin with resp
13、ect to the resins affinity forthe eluent. The suppressor increases the sensitivity of the testmethod by both increasing the conductivity of the analytes anddecreasing the conductivity of the eluent. It also converts theeluent and analytes to the corresponding hydrogen forms of1This test method is un
14、der the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved July 1, 2011. Published August 2011. Originallyapproved in 2007. Last previous edition approved in 2009 as D731909. DOI
15、:10.1520/D7319-11.2For 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.3Available from American National Standards
16、 Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.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.anions. Anions are quantified by in
17、tegration of their responsescompared with an external calibration curve, and are measuredas milligrams/litre, then converted to milligrams/kilograms.The calibration standards are prepared in an aqueous matrix.4.1.1 The use of acid suppression technology is moresignificant for the precision of sulfat
18、e measurement than forchloride. Sulfate precision will be worse if acid suppression isnot used.4.2 Similar methods for chloride and sulfate determinationscan be found in EN 15492 for total chloride, in Test MethodD7328 for total chloride and existent and potential inorganicsulfate by ion chromatogra
19、phy with aqueous sample injection,and in Test Method D7318 for existent inorganic sulfate bypotentiometric lead titration and Test Method D5827 forchloride and other anions in engine coolants by ion chroma-tography.5. Significance and Use5.1 Sulfates and chlorides can be found in filter pluggingdepo
20、sits and fuel injector deposits. The acceptability for use ofthe fuel components and the finished fuels depends on thesulfate and chloride content.5.2 Existent and potential inorganic sulfate and total chlo-ride content, as measured by this test method, can be used asone measure of the acceptability
21、 of gasoline components forautomotive spark-ignition engine fuel use.6. Interferences6.1 Interferences can be caused by substances with similarion chromatographic retention times, especially if they are inhigh concentration compared to the analyte of interest. Sampledilution can be used to minimize
22、or resolve most interferenceproblems.6.2 A water dip (system void, negative peak as shown inFig. 1) can cause interference with some integrators. Usually,for chloride and sulfate determinations, the water dip shouldnot be a problem since the chloride and sulfate peaks are faraway from the water dip.
23、6.3 Given the trace amounts of chloride and sulfate deter-mined in this test method, interferences can be caused bycontamination of glassware, eluent, reagents, and the like. Forexample, sodium leaching from glassware can precipitate withsulfate giving low sulfate results. Take care to ensure thatco
24、ntamination is kept at the lowest possible levels. The use ofpowder-free gloves is highly recommended to prevent samplecontamination.7. Apparatus7.1 Analytical Balance, capable of weighing up to 100 gaccurately to 0.0001 g.7.2 Drying Oven, controlled at 110 6 5C for dryingsodium sulfate and sodium c
25、hloride.7.3 Desiccator, containing freshly activated silica gel (orequivalent desiccant) with moisture content indicator.7.4 Pipets or Volumetric Transferring Devices, appropri-ately sized Class A glass pipets or their equivalent or variablevolume automatic pipets fitted with disposable polypropylen
26、etips.7.5 Volumetric Flasks (with Glass Stoppers), Class A of 10,25, 50, 100, 1000, 2000cc capacity.7.5.1 Container, equipped with a closure to prevent ethanolevaporation, 1 L (for sample collection). See 6.3 for additionalinformation.7.6 Ion Chromatograph, analytical system with all requiredaccesso
27、ries including syringes, columns, suppressor, and de-tector.NOTEChromatogram retention times may be different depending on instruments or columns used.FIG. 1 Typical Ion Chromatogram of a Solution Containing 1 mg/L of Various Anions in WaterD7319 1127.6.1 Injection System, capable of delivering 20 L
28、 with aprecision better than 1 %, or as recommended for this deter-mination by the manufacturer.7.6.2 Pumping System, capable of delivering mobile phaseflows between 0.2 and 2.5 mL/min with a precision better than2%, or as recommended for this determination by the manu-facturer.7.6.3 Guard Column, f
29、or protection of the analytical columnfrom strongly retained constituents. Better separations areobtained with additional theoretical plates.7.6.4 Anion Separator Column, 100 % solvent compatibleand capable of producing satisfactory analyte (sulfate andchloride) separation (Fig. 1).7.6.5 Anion Suppr
30、essor Device, vendor specific and capableof using acid suppression technology.7.6.5.1 Tri-Chamber Approach, 100 % solvent compatibletri-chamber micro packed bed with cation exchange resin (orequivalent). Suppressor device should simultaneously be on-line continuously chemically regenerated to its hy
31、drogen formusing any mineral acid providing H+ ion.7.6.5.2 Continuous Approach, Continuous suppressor mem-brane regeneration.7.6.6 Conductivity Detector, (low volume), temperaturecontrolled to 0.01C, capable of at least 0 to 1000 S/cm on alinear scale.7.6.7 Integrator or Chromatography Data System S
32、oftware,capable of measuring peak areas and retention times, andcorrecting the data in accordance with the baseline of thechromatogram.7.7 Gloves, powder-free examination type.8. Reagents8.1 Purity of ReagentsReagent grade or higher puritychemicals shall be used for the preparation of all samples,st
33、andards, eluent, and regenerator solutions. Unless otherwiseindicated, it is intended that all reagents conform to thespecifications of the Committee on Analytical Reagents of theAmerican Chemical Society, where such specifications areavailable.4Other grades may be used, provided it is firstascertai
34、ned that the reagent is of sufficiently high purity topermit its use without lessening the accuracy of the determi-nation.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water as definedby Type II or better in Specification D1193. For eluentprepar
35、ation and handling, comply with all ion chromatographinstrument and column vendor requirements (for example,filtering, degassing, and the like).8.3 Eluent Buffer Stock SolutionSodium bicarbonate(NaHCO3) 1.0 mM and sodium carbonate (Na2CO3) 3.2 mM.Dissolve 8.4 6 0.0005 g of NaHCO3and 33.92 6 0.0005 g
36、 ofNa2CO3in reagent water in a 1-L Type A volumetric flask anddilute to volume. Dilute 10.0 mL of this stock solution to 1 Lin a 1-L Type A volumetric flask with degassed reagent water.The eluent solution used may be different if other system oranalytical columns are used.NOTE 1Other volumes of stoc
37、k solution can be prepared usingappropriate ratios of reagents. Follow the specific guidelines for thissolution from the vendor of the column being used. Alternatively, thissolution can be purchased from a qualified vendor.8.4 Suppressor Regenerant Solution for Suppressor0.1 Msulfuric acid. Carefull
38、y add 334 mL of reagent grade sulfuricacid (relative density 1.84) to approximately 500 mL reagentwater in a 1-L volumetric flask. (WarningThis will generatea very hot solution.Allow it to cool before diluting to 1000 mLvolume. Never add water to concentrated acid.) Dilute to 1000mL with reagent wat
39、er, and label this solution as 10.0 Msulfuric acid. Dilute 10.0 mL of this concentrate to 1000 mLwith reagent water for the final 0.1 M working suppressorsolution.NOTE 2Other volumes of this solution can be prepared using appro-priate ratios of reagents. Follow the specific guidelines for this solut
40、ionfrom the vendor of the suppressor being used.8.5 Sodium Sulfateanhydrous, reagent grade, 99 % mini-mum purity. (WarningDo not ingest. Avoid unnecessaryexposure.)8.6 Sodium ChlorideACS or reagent grade, 99 % mini-mum purity.8.7 Ethanoldenatured with methanol, formula 3A or his-tological grade etha
41、nol, anhydrous, denatured with ethyl ac-etate, methylisobutyl ketone and hydrocarbon naphtha.(WarningFlammable, toxic, and may be harmful or fatal ifingested or inhaled. Avoid skin contact.)8.8 Hydrogen PeroxideACS reagent grade, 30 wt % inwater.8.9 Hydrogen Peroxide Solution, 30 %commerciallyavaila
42、ble 30 % hydrogen peroxide solution.9. Preparation of Standard Solutions9.1 Stock Solutions:9.1.1 Sulfate Stock Solution, approximately 2000 mg/LToensure dryness, place anhydrous sodium sulfate (5 g) in adrying oven at 110C for at least an hour, cool, and store in adesiccator. Accurately weigh 2.96
43、g anhydrous sodium sulfateto the nearest tenth of a milligram and transfer to a 1Lvolumetric flask. Add water to dissolve the sodium sulfate, andmake to volume. Calculate the concentration of sulfate in thesolution in accordance with Eq 1. Other volumes of stocksolution can be prepared using the app
44、ropriate ratio of re-agents.Stock Sulfate mg/L!5gNa2SO4!0.6764!1000 mg/g!/1 L (1)where:gNa2SO4= weight in grams of Na2SO4dissolved in 1 L,and0.6764 = weight percent sulfate in Na2SO4.9.1.2 Chloride Stock Solution (approximately 2000 mg/L)To ensure dryness, place sodium chloride (5 g) in a dryingoven
45、 at 110C for at least an hour, cool, and store in adesiccator. Accurately weigh 3.30 g dried sodium chloride to4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society
46、, 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.D7319 113the nearest tenth of a milligram and transfer to a 1Lvolumetric flask. Add water to dissolve the
47、sodium chlorideand make to volume. Calculate the concentration of chloride inthe solution in accordance with Eq 2. Other volumes of stocksolution can be prepared using the appropriate ratio of re-agents.Stock Chloride mg/L!5g NaCl!0.6068!1000 mg/g!/1 L (2)where:g NaCl = weight in grams of NaCl disso
48、lved in 1 L, and0.6068 = weight percent chloride in NaCl.9.2 Chloride and Sulfate Standards in WaterAdd waterand sulfate and chloride stock solutions are added to a 1Lglass volumetric flask in accordance with Table 1 to achievethe desired standard.9.2.1 Chloride and sulfate stock solutions from 9.1
49、areadded quantitatively into the flask and mixed quantitativelywith water in accordance with Table 1. Be very careful tomeasure the exact volumes of the sulfate and chloride stocksolutions that are added to the flask, and fill the flask to 1.00 Lwith water. The sulfate and chloride concentrations of eachstandard are calculated in accordance with Eq 3 and Eq 4.Sulfate in Standard mg/L!5Va3 Ca/ V (3)Chloride in Standard mg/L!5Vb3 Cb/ V (4)where:Va= volume of sulfate stock solution (9.1.1), in mL,Ca= concentration of sulfate stock (Eq 1),
