1、Designation: D 7328 07e1An American National StandardStandard Test Method forDetermination of Total and Potential Inorganic Sulfate andTotal Inorganic Chloride in Fuel Ethanol by IonChromatography Using Aqueous Sample Injection1This standard is issued under the fixed designation D 7328; the number i
2、mmediately following the designation indicates the 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 (e) indicates an editorial change since the last revision or reapproval.e1NOTEAdded
3、standards previously under development to the Referenced Documents and 4.2 editorially in April 2007.1. Scope1.1 This test method covers an ion chromatographic proce-dure for the determination of the total and potential inorganicsulfate and total inorganic chloride content in hydrous andanhydrous de
4、natured ethanol to be used in motor fuel applica-tions. It is intended for the analysis of ethanol samplescontaining between 0.55 and 20 mg/kg of total inorganicsulfate, 4.0 to 20 mg/kg of potential inorganic sulfate, and 0.75to 50 mg/kg of total inorganic chloride.1.2 The values stated in SI units
5、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 theresponsibility of the user of this standard to establish appro-priate safety and health practic
6、es 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 Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 4052 Test Method for Density and R
7、elative Density ofLiquids by Digital Density MeterD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD 5827 Test Method for Analysis of Engine Coolant forChloride and Other Anions by Ion ChromatographyD 6299
8、Practice for Applying Statistical Quality AssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceD 6792 Guide for Quality System in Petroleum Productsand Lubricants Testing LaboratoriesD 7318 Test Method for Total Inorganic Sulfate in Ethanolby Potentiometric TitrationD 7319 Test Me
9、thod for Determination of Total and Poten-tial Sulfate and Inorganic Chloride in Fuel Ethanol byDirect Injection Suppressed Ion Chromatography2.2 Other Standard:ISO/CEN15492 Ethanol as a Blending Component forPetrol Determination of Inorganic Chloride IonChromatographic Method33. Terminology3.1 Defi
10、nitions of Terms Specific to This Standard:3.1.1 inorganic chloride, nchloride present as hydrochlo-ric acid, ionic salts of this acid, or mixtures of these.3.1.2 inorganic sulfate, nsulfate species present as sulfu-ric acid, ionic salts of this acid, or mixtures of these.3.1.3 potential sulfate, nt
11、otal sulfur species present in thesample that can be oxidized to inorganic sulfate in the presenceof an oxidizing agent.3.1.4 total sulfate, ninorganic sulfate species actuallypresent in the sample at the time of analysis with no oxidationtreatment.4. Summary of Test Method4.1 For total inorganic su
12、lfate and chloride, a small volumeof a sample is evaporated to dryness and reconstituted to theinitial sample volume with deionized water, and injected intoan ion chromatograph consisting of appropriate ion exchangecolumns, suppressor and a conductivity detector. For potentialsulfate, a small volume
13、 of a sample is evaporated to drynessand reconstituted to the initial sample volume with 0.90 %hydrogen peroxide solution in water, and injected into an ionchromatograph. Ions are separated based on their affinity for1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Produ
14、cts and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved Jan. 1, 2007. Published February 2007.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
15、ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from International Organization for Standardization (ISO), 1 rue deVaremb, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.1Copyright ASTM International, 100 Barr Harbor Dr
16、ive, PO Box C700, West Conshohocken, PA 19428-2959, United States.exchange sites of the resin with respect to the resins affinity forthe eluent. The suppressor increases the sensitivity of themethod by both increasing the conductivity of the analytes anddecreasing the conductivity of the eluent. The
17、 suppressorconverts the eluent and the analytes to the correspondinghydrogen form acids. Anions in the aqueous sample arequantified by integration of their responses compared with anexternal calibration curve, calculated as mg/L for each ion. Thecalibration standards are prepared from suitable salts
18、 dissolvedin water solutions. Total or potential sulfate and chlorideconcentrations may be calculated as mg/kg by measuring thedensity of the original sample.4.2 Similar methods for chloride and sulfate determinationscan be found in Test Method D 5827 for engine coolant, andfor ethanol in ISO/CEN154
19、92, Test Method D 7319 by ionchromatography with direct sample injection, and for sulfateonly in Test Method D 7318 by potentiometric lead titration.5. Significance and Use5.1 Sulfates and chlorides may be found in filter pluggingdeposits and fuel injector deposits. The acceptability for use ofthe f
20、uel components and the finished fuels depends on thesulfate and chloride content.5.2 Total and potential sulfate and total chloride content, asmeasured by this test method, can be used as one measure ofthe acceptability of gasoline components for automotive spark-ignition engine fuel use.6. Interfer
21、ences6.1 Interferences can be caused by substances with similarion chromatographic retention times, especially if they are inhigh concentration compared to the analyte of interest. Sampledilution or standard addition can be used to minimize orresolve most interference problems.6.2 A water dip (syste
22、m void, negative peak as shown inFig. 1) may 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 farenough away from the water dip.6.3 Given the trace amounts of chloride and sulfate
23、deter-mined by this method, interferences can be caused by contami-nation of glassware, eluents, reagents, etc. Great care must betaken to ensure that contamination is kept at the lowest possiblelevels. The use of powder-free gloves is highly recommendedto prevent sample contamination.7. Apparatus7.
24、1 Analytical Balance, at least 2000 g capacity, capable ofweighing accurately to 0.01 g.7.1.1 Analytical Balance, at least 100 g capacity, capable ofweighing accurately to 0.0001 g.7.2 Drying Oven, controlled at 110 6 5C for dryingsodium sulfate and sodium chloride.7.3 Desiccator, containing freshly
25、 activated silica gel (orequivalent desiccant) with moisture content indicator.7.4 Pipettes or Volumetric Transferring Devices, Class Aglass pipettes or their equivalent of 2.0 cc capacity or auto-matic pipettes fitted with disposable polypropylene tips.7.4.1 Plastic Syringe, 10 cc disposable, optio
26、nally fittedwith a 0.2 m syringe filter (must be chloride and sulfate-free).7.5 Volumetric Flask, ClassAof 1 L capacity and ClassAof10 mL capacity.7.6 Ion Chromatograph, Analytical system with all requiredaccessories including syringes, columns, suppressor, gases, anddetector.7.6.1 Injection System,
27、 capable of delivering 25 L with aprecision better than 1 %.7.6.2 Pumping System, capable of delivering mobile phaseflows between 0.5 and 1.5 mL/min with a precision better than5%.7.6.3 Guard Column, for protection of the analytical columnfrom strongly retained constituents. Better separations areob
28、tained with greater separating power.FIG. 1 Typical Ion Chromatogram of a Solution Containing 1 mg/kg of Various Anions in WaterD732807e127.6.4 Anion Separator Column, capable of producing satis-factory analyte separation (see Fig. 1).7.6.5 Anion Suppressor Device, micro membrane suppres-sor or equi
29、valent. A cation exchange column in the hydrogenform has been used successfully, but it will periodically need tobe regenerated as required. This is indicated by a highbackground conductivity and low analyte response.7.6.6 Conductivity Detector, low volume (2 L) and flow,temperature compensated, cap
30、able of at least 0 to 1000 S/cmon a linear scale.7.6.7 Integrator or Chromatography Data System Software,capable of measuring peak areas and retention times, andcorrecting the data according to the baseline of the chromato-gram.7.7 Gloves, powder-free examination type.7.8 Hot Block, aluminum, capabl
31、e of being heated to 65Cwith suitable holes to hold 15 mL glass vials, with a method offlowing nitrogen over inserted samples.7.9 Glass Vials, 15 mL with screw top.8. Reagents8.1 Purity of ReagentsReagent grade or higher puritychemicals shall be used for the preparation of all samples,standards, elu
32、ents, 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 firstascertained that th
33、e 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 in Specification D 1193. For eluent preparation andhandling,
34、comply with all ion chromatograph instrument andcolumn vendor requirements (for example, filtering, degassing,etc.).8.3 Eluent Buffer SolutionThe eluent solution used de-pends on the systems or analytical columns that are used(contact instrument and column vendors). For the chromato-grams in Fig. 1,
35、 the following eluent buffer was used: Sodiumbicarbonate (NaHCO3) 1.7 mM and sodium carbonate(Na2CO3) 1.8 mM. Dissolve 2.8563 6 0.0005 g of NaHCO3and 3.8157 6 0.0005 g of Na2CO3in reagent water in a 1-LType A volumetric flask and dilute to volume. Dilute 100 mLof this concentrate to 2000 mL with rea
36、gent water for the finalworking eluent solution. Other volumes of stock solution maybe prepared using appropriate ratios of reagents. Follow thespecific guidelines for this solution from the vendor of thecolumn being used. Alternatively, this solution can be pur-chased from a qualified vendor.8.4 Su
37、ppressor Solution for Membrane Suppressor, 0.025 Nsulfuric acid. Carefully add 13.7 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
38、. Never add water to concentrated acid!) Dilute to 1000mL with reagent water, and label this solution as 0.50 Nsulfuric acid. Dilute 100 mL of this concentrate to 2000 mLwith reagent water for the final working suppressor solution.Other volumes of stock solution may be prepared usingappropriate rati
39、os of reagents. Follow the specific guidelinesfor this solution from the vendor of the column being used.8.5 Sodium Sulfate, anhydrous, reagent grade, 99 % mini-mum purity. (WarningDo not ingest; avoid unnecessaryexposure.)8.6 Sodium Chloride, ACS reagent grade, 99 % minimumpurity.8.7 Ethanol, denat
40、ured with methanol, formula 3A or his-tological grade ethanol, anhydrous, denatured with ethyl ac-etate, methylisobutyl ketone and hydrocarbon naphtha.(WarningFlammable; toxic; may be harmful or fatal ifingested or inhaled; avoid skin contact.)8.8 Hydrogen Peroxide Solution, 30 %, commercially avail
41、-able 30 % hydrogen peroxide solution.8.9 Nitrogen Gas, 99.99 mol % pure, free of hydrocarbons.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 h
42、our, cool and store in adesiccator. Accurately weigh 2.96 g anhydrous sodium sulfateto the nearest tenth of a milligram and transfer toa1Lvolumetric flask. Add Type II water to dissolve the sodiumsulfate and make to volume. Calculate the concentration ofsulfate in the solution according to Eq 1. Oth
43、er volumes ofstock solution may be prepared using the appropriate ratio ofreagents.stock sulfate mg/L! 5 gNa2SO4! 0.6764! 1000 mg/g! /1L (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/LTo e
44、nsure dryness, place sodium chloride (5 g) in a dryingoven at 110C for at least an hour, cool and store in adesiccator. Accurately weigh 3.30 g dried sodium chloride tothe nearest tenth of a milligram and transfer toa1Lvolumetricflask. Add Type II water to dissolve the sodium chloride andmake to vol
45、ume. Calculate the concentration of chloride in thesolution according to Eq 2. Other volumes of stock solutionmay be prepared using the appropriate ratio of reagents.stock chloride mg/L! 5 g NaCl! 0.6068! 1000 mg/g! /1L (2)where:g NaCl = weight in grams of NaCl dissolved in 1 L, and0.6068 = weight p
46、ercent chloride in NaCl.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Dorset, U.K., and the United
47、States Pharmacopeia andNational Formulatory, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D732807e139.2 Chloride and Sulfate Standards in WaterType II waterand sulfate and chloride stock solutions are added toa1Lglassvolumetric flask according to Table 1 to achieve the desiredstandard. T
48、hese standard solutions should be discarded andremade every month.9.2.1 Chloride and sulfate stock solutions from 9.1 areadded quantitatively into the flask, mixed quantitatively withType II water according to Table 1. Be very careful to measurethe exact volumes of the sulfate and chloride stock sol
49、utionsthat are added to the flask, and to fill the flask to 1.00 L withType II water. The sulfate and chloride concentrations of eachstandard are calculated according to Eq 3(a) and Eq 3(b).sulfate in standard mg/L!5Va 3 Ca / V a! (3)chloride in standard mg/L!5Vb 3 Cb / V b!where:Va = volume of sulfate stock solution (for example, Table1, Column 3), in mL,Ca = concentration of sulfate stock (Eq 1), in mg/L,Vb = volume of chloride stock solution (for example, Table1, Column 2), in mL,Cb = concentration of chloride stock (Eq 2), in mg/L, andV = fi
