1、Designation: D7328 11D7328 13Standard 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 0.55 and
4、 20 mg/kg of existent inorganic sulfate, 4.0 to 20 mg/kgof potential inorganic sulfate, and 0.75 to 50 mg/kg of total inorganic chloride.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to
5、 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. Material Safety Data Sheets are available for reagent
6、s 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 for Manual Sampling of Petroleum and Petroleum Pro
7、ductsD4177 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 Charting Techniques to Evaluate Analytical Measure-m
8、ent 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 Potential Sulfate and Inorganic Chloride in Fuel
9、 Ethanol and Butanol byDirect Injection Suppressed Ion Chromatography2.2 Other Standard:ISO/CEN15492 Ethanol as a Blending Component for Petrol Determination of Inorganic Chloride Ion ChromatographicMethod 33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 existent inorganic sul
10、fate, 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 of these.1 This test method is under the jurisdiction of ASTM Committee D02 on Pe
11、troleum Products Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.03 on Elemental Analysis.Current edition approved July 1, 2011Sept. 15, 2013. Published August 2011September 2013. Originally approved in 2007. Last previous edition approved in 20072011as D73
12、28D7328 11.071. DOI: 10.1520/D7328-11.10.1520/D7328-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Avai
13、lable 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 user of an ASTM standard an indication of what changes have been made to the
14、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 published by ASTM is to be considered the official document.*A Summary of
15、 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 sulfuric acid, ionic salts of this acid, or mixtures of these.3.1.4 potential sul
16、fate, ntotal sulfur inorganic sulfate species present in the sample that can be oxidized to inorganic sulfatein the presence of 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
17、 to dryness 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
18、 the initial 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 b
19、oth increasing 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 calibrati
20、on curve,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 chlo
21、ride and 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 an
22、d chlorides 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
23、, can be 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
24、 interest. 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 pr
25、oblem since 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 1326.3 Given the trace amounts of chloride and sulfate determined by this method, interferences can be caused by contamina
26、tionof 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 capacity, capable of weighing
27、accurately to 0.01 g.7.1.1 Analytical Balance, at least 100 g capacity, capable of weighing accurately to 0.0001 g.7.2 Drying Oven, controlled at 110 6 5C for drying sodium sulfate and sodium chloride.7.3 Desiccator, containing freshly activated silica gel (or equivalent desiccant) with moisture con
28、tent indicator.7.4 Pipettes or Volumetric Transferring Devices, Class A glass pipettes or their equivalent of 2.0 cc capacity or automaticpipettes fitted with disposable polypropylene tips.7.4.1 Plastic Syringe, 10 cc disposable, optionally fitted with a 0.2 m syringe filter (must be chloride and su
29、lfate-free).7.5 Volumetric Flask, Class A of 1 L capacity and Class A of 10 mL capacity.7.6 Ion Chromatograph, Analytical system with all required accessories including syringes, columns, suppressor, gases, anddetector.7.6.1 Injection System, capable of delivering 25 L with a precision better than 1
30、 %.7.6.2 Pumping System, capable of delivering mobile phase flows between 0.5 and 1.5 mL/min with a precision better than 5 %.7.6.3 Guard Column, for protection of the analytical column from strongly retained constituents. Better separations are obtainedwith greater separating power.7.6.4 Anion Sepa
31、rator 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, but it will periodically need to be regenerated as required. This is indicate
32、d by a high backgroundconductivity and low analyte response.7.6.6 Conductivity Detector, low volume (2 L) and flow, temperature compensated, capable of at least 0 to 1000 S/cm ona linear scale.7.6.7 Integrator or Chromatography Data System Software, capable of measuring peak areas and retention time
33、s, 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 65C with suitable holes to hold 15 mL glass vials, with a method offlowing nitrogen over inserted samples.7.9 Glass Vials, 15 mL with s
34、crew 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 otherwise indicated, it is intended that all reagents conform to the specifications of theCommittee onAnalytical R
35、eagents 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 purity to permit its use without lessening the accuracyof the determination.8.2 Purity of WaterUnless otherwise indica
36、ted, 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 instrument and columnvendor requirements (for example, filtering, degassing, etc.).8.3 Eluent Buffer SolutionThe eluen
37、t 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: Sodium bicarbonate(NaHCO3) 1.7 mM and sodium carbonate (Na2CO3) 1.8 mM. Dissolve 2.8563 6 0.0005 g of NaHCO3 and 3
38、.8157 6 0.0005 gof Na2CO3 in reagent water in a 1-L Type A volumetric flask and dilute to volume. Dilute 100 mL of this concentrate to 2000 mLwith reagent water for the final working eluent solution. Other volumes of stock solution may be prepared using appropriate ratiosof reagents. Follow the spec
39、ific guidelines for this solution from the vendor of the column being used. Alternatively, this solutioncan be purchased from a qualified vendor.8.4 Suppressor Solution for Membrane Suppressor, 0.025 N sulfuric acid. Carefully add 13.7 mL of reagent grade sulfuric acid(relative density 1.84) to appr
40、oximately 500 mL reagent water in a 1-L volumetric flask. (Warning This will generate a veryhot solution. Allow it to cool before diluting to 1000 mL volume. Never add water to concentrated acid!) Dilute to 1000 mL with4 Reagent Chemicals, American Chemical Society Specifications, American Chemical
41、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 United States Pharmacopeia and National Formulatory,U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD
42、.D7328 133reagent water, and label this solution as 0.50 N sulfuric acid. Dilute 100 mL of this concentrate to 2000 mL with reagent waterfor the final working suppressor solution. Other volumes of stock solution may be prepared using appropriate ratios of reagents.Follow the specific guidelines for
43、this solution from the vendor of the column being used.8.5 Sodium 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 gr
44、ade ethanol, anhydrous, denatured with ethyl acetate,methylisobutyl 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 G
45、as, 99.99 mol % pure, free of hydrocarbons.9. Preparation of Standard Solutions9.1 Stock Solutions:9.1.1 Sulfate Stock Solution, approximately 2000 mg/LTo ensure dryness, place anhydrous sodium sulfate (5 g) in a dryingoven at 110C for at least an hour, cool and store in a desiccator.Accurately weig
46、h 2.96 g anhydrous sodium sulfate to the nearesttenth of a milligram and transfer to a 1 L volumetric flask. Add Type II water to dissolve the sodium sulfate and make to volume.Calculate the concentration of sulfate in the solution according to Eq 1. Other volumes of stock solution may be prepared u
47、singthe appropriate ratio of reagents.stock sulfatemg/L!5gNa2SO4!0.6764!1000 mg/g!/1L (1)where:g 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 mg/LTo ensure dryness, place sodium chloride (5 g) in a
48、 drying oven at110C for at least an hour, cool and store in a desiccator. Accurately weigh 3.30 g dried sodium chloride to the nearest tenth ofa milligram and transfer to a 1 Lvolumetric flask.AddType II water to dissolve the sodium chloride and make to volume. Calculatethe concentration of chloride
49、 in the solution according to Eq 2. Other volumes of stock solution may be prepared using theappropriate ratio of reagents.stock chloridemg/L!5gNaCl!0.6068!1000 mg/g!/1L (2)where:g NaCl = weight in grams of NaCl dissolved in 1 L, and0.6068 = weight percent chloride in NaCl.9.2 Chloride and Sulfate Standards in WaterType II water and sulfate and chloride stock solutions are added to a 1 L glassvolumetric flask according to Table 1 to achieve the desired standard. These standard solutions should be discarded and remadeevery month.9.2.1 Chlorid
