1、Designation: D7328 13D7328 16Standard Test Method forDetermination of Existent and Potential Inorganic Sulfateand Total Inorganic Chloride in Fuel Ethanol by IonChromatography Using Aqueous Sample Injection1This standard is issued under the fixed designation D7328; the number immediately following t
2、he 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 () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method cover
3、s an ion chromatographic procedure for the determination of the existent inorganic and potentialsulfate and total inorganic chloride content in hydrous and anhydrous denatured ethanol to be used in motor fuel applications. Itis intended for the analysis of ethanol samples containing between 0.550.55
4、 mgkg and 2020 mg mg/kg kg of existent inorganicsulfate, 4.04.0 mgkg to 2020 mg mg/kg kg of potential inorganic sulfate, and 0.750.75 mgkg to 5050 mg mg/kg kg of totalinorganic chloride.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in th
5、is standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Mate
6、rial Safety Data Sheets are available for reagents and materials. Review them for hazards prior tousage.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density MeterD4057 Practice f
7、or Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD5827 Test Method for Analysis of Engine Coolant for Chloride and Other Anions by Ion ChromatographyD6299 Practice for Applying Statistical Quality Assurance and Control Cha
8、rting Techniques to Evaluate Analytical Measure-ment System PerformanceD6792 Practice for Quality System in Petroleum Products and Lubricants Testing LaboratoriesD7318 Test Method for Existent Inorganic Sulfate in Ethanol by Potentiometric TitrationD7319 Test Method for Determination of Existent and
9、 Potential Sulfate and Inorganic Chloride in Fuel Ethanol and Butanol byDirect Injection Suppressed Ion Chromatography2.2 Other Standard:ISO/CEN15492 Ethanol as a Blending Component for Petrol Determination PetrolDetermination of Inorganic Chloride Ion ChlorideIon Chromatographic Method 33. Terminol
10、ogy3.1 Definitions of Terms Specific to This Standard:3.1.1 existent inorganic sulfate, ninorganic sulfate species actually present in the sample at the time of analysis with nooxidation treatment.3.1.2 inorganic chloride, nchloride present as hydrochloric acid, ionic salts of this acid, or mixtures
11、 of these.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved Sept. 15, 2013Oct. 1, 2016. Published September 2013December 2016. Ori
12、ginally approved in 2007. Last previous edition approved in 20112013as D7328 11.D7328 13. DOI: 10.1520/D7328-13.10.1520/D7328-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume informatio
13、n, refer to the standards Document Summary page on the ASTM website.3 Available from International Organization for Standardization (ISO), 1 rue de Varemb, Case postale 56, CH-1211, Geneva 20, Switzerland, http:/www.iso.ch.This document is not an ASTM standard and is intended only to provide the use
14、r of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as
15、 published by ASTM is to be considered the official document.*A Summary 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 States13.1.3 inorganic sulfate, nsulfate species present as sulfuri
16、c acid, ionic salts of this acid, or mixtures of these.3.1.4 potential sulfate, ntotal inorganic sulfate species present after the sample has been reacted with an oxidizing agent.4. Summary of Test Method4.1 For existent inorganic sulfate and chloride, a small volume of a sample is evaporated to dry
17、ness and reconstituted to theinitial sample volume with deionized water, and injected into an ion chromatograph consisting of appropriate ion exchangecolumns, suppressor and a conductivity detector. For potential sulfate, a small volume of a sample is evaporated to dryness andreconstituted to the in
18、itial sample volume with 0.90 % hydrogen peroxide solution in water, and injected into an ionchromatograph. Ions are separated based on their affinity for exchange sites of the resin with respect to the resins affinity for theeluent. The suppressor increases the sensitivity of the method by both inc
19、reasing the conductivity of the analytes and decreasingthe conductivity of the eluent. The suppressor converts the eluent and the analytes to the corresponding hydrogen form acids.Anions in the aqueous sample are quantified by integration of their responses compared with an external calibration curv
20、e,calculated as mg/L for each ion. The calibration standards are prepared from suitable salts dissolved in water solutions. Existentor potential inorganic sulfate and chloride concentrations may be calculated as mg/kg by measuring the density of the originalsample.4.2 Similar methods for chloride an
21、d sulfate determinations can be found in Test Method D5827 for engine coolant, and forethanol in ISO/CEN15492, Test Method D7319 by ion chromatography with direct sample injection, and for sulfate only in TestMethod D7318 by potentiometric lead titration.5. Significance and Use5.1 Sulfates and chlor
22、ides may be found in filter plugging deposits and fuel injector deposits. The acceptability for use of thefuel components and the finished fuels depends on the sulfate and chloride content.5.2 Existent and potential inorganic sulfate and total chloride content, as measured by this test method, can b
23、e used as onemeasure of the acceptability of gasoline components for automotive spark-ignition engine fuel use.6. Interferences6.1 Interferences can be caused by substances with similar ion chromatographic retention times, especially if they are in highconcentration compared to the analyte of intere
24、st. Sample dilution or standard addition can be used to minimize or resolve mostinterference problems.6.2 A water dip (system void, negative peak as shown in Fig. 1) may cause interference with some integrators. Usually, forchloride and sulfate determinations, the water dip should not be a problem s
25、ince the chloride and sulfate peaks are far enough awayfrom the water dip.FIG. 1 Typical Ion Chromatogram of a Solution Containing 1 mg/kg of Various Anions in WaterD7328 1626.3 Given the trace amounts of chloride and sulfate determined by this method, interferences can be caused by contaminationof
26、glassware, eluents, reagents, etc. Great care must be taken to ensure that contamination is kept at the lowest possible levels. Theuse of powder-free gloves is highly recommended to prevent sample contamination.7. Apparatus7.1 Analytical Balance, at least 2000 g 2000 g capacity, capable of weighing
27、accurately to 0.01 g.0.01 g.7.1.1 Analytical Balance, at least 100 g 100 g capacity, capable of weighing accurately to 0.0001 g.0.0001 g.7.2 Drying Oven, controlled at 110110 C 6 5C5 C for drying sodium sulfate and sodium chloride.7.3 Desiccator, containing freshly activated silica gel (or equivalen
28、t desiccant) with moisture content indicator.7.4 Pipettes or Volumetric Transferring Devices, ClassAglass pipettes or their equivalent of 2.0 cc 2.0 cc capacity or automaticpipettes fitted with disposable polypropylene tips.7.4.1 Plastic Syringe, 10 cc 10 cc disposable, optionally fitted with a 0.2
29、m 0.2 m syringe filter (must be chloride andsulfate-free).7.5 Volumetric Flask, Class A of 1 L 1 L capacity and Class A of 10 mL 10 mL capacity.7.6 Ion Chromatograph, Analytical system with all required accessories including syringes, columns, suppressor, gases, anddetector.7.6.1 Injection System, c
30、apable of delivering 25 L 25 L with a precision better than 1 %.7.6.2 Pumping System, capable of delivering mobile phase flows between 0.50.5 mLmin and 1.51.5 mL mL/min min with aprecision better than 5 %.7.6.3 Guard Column, for protection of the analytical column from strongly retained constituents
31、. Better separations are obtainedwith greater separating power.7.6.4 Anion Separator Column, capable of producing satisfactory analyte separation (see Fig. 1).7.6.5 Anion Suppressor Device, micro membrane suppressor or equivalent.Acation exchange column in the hydrogen form hasbeen used successfully
32、, but it will periodically need to be regenerated as required. This is indicated by a high backgroundconductivity and low analyte response.7.6.6 Conductivity Detector, low volume (2 L) (2 L) and flow, temperature compensated, capable of at least 00 Scm to10001000 S S/cm cm on a linear scale.7.6.7 In
33、tegrator or Chromatography Data System Software, capable of measuring peak areas and retention times, and correctingthe data according to the baseline of the chromatogram.7.7 Gloves, powder-free examination type.7.8 Hot Block, aluminum, capable of being heated to 65C65 C with suitable holes to hold
34、15 mL 15 mL glass vials, with amethod of flowing nitrogen over inserted samples.7.9 Glass Vials, 15 mL 15 mL with screw top.8. Reagents8.1 Purity of ReagentsReagent grade or higher purity chemicals shall be used for the preparation of all samples, standards,eluents, and regenerator solutions. Unless
35、 otherwise indicated, it is intended that all reagents conform to the specifications of theCommittee onAnalytical Reagents of theAmerican Chemical Society, where such specifications are available.4 Other grades maybe used, provided it is first ascertained that the reagent is of sufficiently high pur
36、ity to permit its use without lessening the accuracyof the determination.8.2 Purity of WaterUnless otherwise indicated, reference to water shall be understood to mean reagent water as defined byType II in Specification D1193. For eluent preparation and handling, comply with all ion chromatograph ins
37、trument and columnvendor requirements (for example, filtering, degassing, etc.).8.3 Eluent Buffer SolutionThe eluent solution used depends on the systems or analytical columns that are used (contactinstrument and column vendors). For the chromatograms in Fig. 1, the following eluent buffer was used:
38、 Sodium bicarbonate(NaHCO3) 1.7 mM 1.7 mM and sodium carbonate (Na2CO3) 1.8 mM. 1.8 mM. Dissolve 2.85632.8563 g 6 0.0005 g 0.0005 g ofNaHCO3 and 3.81573.8157 g 6 0.0005 g 0.0005 g of Na2CO3 in reagent water in a 1-L1 L Type A volumetric flask and dilute tovolume. Dilute 100 mL 100 mL of this concent
39、rate to 2000 mL 2000 mL with reagent water for the final working eluent solution.Other volumes of stock solution may be prepared using appropriate ratios of reagents. Follow the specific guidelines for thissolution from the vendor of the column being used. Alternatively, this solution can be purchas
40、ed from a qualified vendor.4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Dorset, U.K., and the U
41、nited States Pharmacopeia and National Formulatory,U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.D7328 1638.4 Suppressor Solution for Membrane Suppressor, 0.025 N 0.025 N sulfuric acid. Carefully add 13.7 mL 13.7 mL of reagentgrade sulfuric acid (relative density 1.84) to approximately 5
42、00 mL 500 mL reagent water in a 1-L1 L volumetric flask.(Warning This will generate a very hot solution.Allow it to cool before diluting to 1000 mL1000 mLvolume. Never add waterto concentrated acid!) Dilute to 1000 mL1000 mLwith reagent water, and label this solution as 0.50 N 0.50 N sulfuric acid.
43、Dilute100 mL 100 mL of this concentrate to 2000 mL 2000 mL with reagent water for the final working suppressor solution. Othervolumes of stock solution may be prepared using appropriate ratios of reagents. Follow the specific guidelines for this solutionfrom the vendor of the column being used.8.5 S
44、odium Sulfate, anhydrous, reagent grade, 99 % minimum purity. (WarningDo not ingest; avoid unnecessary exposure.)8.6 Sodium Chloride, ACS reagent grade, 99 % minimum purity.8.7 Ethanol, denatured with methanol, formula 3A or histological grade ethanol, anhydrous, denatured with ethyl acetate,methyli
45、sobutyl ketone and hydrocarbon naphtha. (WarningFlammable; toxic; may be harmful or fatal if ingested or inhaled;avoid skin contact.)8.8 Hydrogen Peroxide Solution, 30 %, commercially available 30 % hydrogen peroxide solution.8.9 Nitrogen Gas, 99.99 mol % pure, free of hydrocarbons.9. Preparation of
46、 Standard Solutions9.1 Stock Solutions:9.1.1 Sulfate Stock Solution, approximately 2000 2000 mgmg/LLTo ensure dryness, place anhydrous sodium sulfate (5 g)(5 g) in a drying oven at 110C110 C for at least an hour, cool and store in a desiccator.Accurately weigh 2.96 g 2.96 g anhydroussodium sulfate t
47、o the nearest tenth of a milligram and transfer to a 1 L 1 L volumetric flask. Add Type II water to dissolve thesodium sulfate and make to volume. Calculate the concentration of sulfate in the solution according to Eq 1. Other volumes ofstock solution may be prepared using the appropriate ratio of r
48、eagents.stock sulfatemg/L!5gNa2SO4!0.6764!1000 mg/g!/1L (1)where:g Na2SO4 = weight in grams of Na2SO4 dissolved in 1 L, andg Na2SO4 = weight in grams of Na2SO4 dissolved in 1 L, and0.6764 = weight percent sulfate in Na2SO4.9.1.2 Chloride Stock Solution, approximately 2000 2000 mgmg/LLTo ensure dryne
49、ss, place sodium chloride (5 g) (5 g) ina drying oven at 110C110 C for at least an hour, cool and store in a desiccator. Accurately weigh 3.30 g 3.30 g dried sodiumchloride to the nearest tenth of a milligram and transfer to a 1 L 1 L volumetric flask. Add Type II water to dissolve the sodiumchloride and make to volume. Calculate the concentration of chloride in the solution according to Eq 2. Other volumes of stocksolution may be prepared using the appropriate ratio of reagents.stock chloridemg/L!5gNaCl!0.6068!1000 m
