ASTM D7319-07

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation:D7319–07
Standard Test Method for
Determination of Total and Potential Sulfate and Inorganic
Chloride in Fuel Ethanol by Direct Injection Suppressed Ion
Chromatography
This standard is issued under the fixed designation D7319; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D6299 Practice for Applying Statistical Quality Assurance
and Control Charting Techniques to Evaluate Analytical
1.1 This test method covers a direct injection ion chromato-
Measurement System Performance
graphic procedure for determining the total and potential
D6792 Practice for Quality System in Petroleum Products
inorganic sulfate and total inorganic chloride content in hy-
and Lubricants Testing Laboratories
drousandanhydrousdenaturedethanoltobeusedinmotorfuel
D7318 Test Method for Total Inorganic Sulfate in Ethanol
applications. It is intended for the analysis of ethanol samples
by Potentiometric Titration
containing between 1.0–20 mg/kg of total or potential inor-
D7328 Test Method for Determination of Total and Poten-
ganic sulfate and 1.0–50 mg/kg of inorganic chloride.
tial Inorganic Sulfate and Total Inorganic Chloride in Fuel
1.2 The values stated in SI units are to be regarded as
Ethanol by Ion Chromatography Using Aqueous Sample
standard. No other units of measurement are included in this
Injection
standard.
1.3 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
3.1 Definitions of Terms Specific to This Standard:
responsibility of the user of this standard to establish appro-
3.1.1 inorganic chloride, n—chloride present as hydrochlo-
priate safety and health practices and determine the applica-
ric acid, ionic salts of this acid, or mixtures of these.
bility of regulatory limitations prior to use. Material Safety
-2
3.1.2 inorganic sulfate, n—sulfate (SO ) species present
Data Sheets are available for reagents and materials. Review
as sulfuric acid, ionic salts of this acid, or mixtures of these.
them for hazards prior to usage.
3.1.3 potential sulfate, n—total sulfur species present in the
2. Referenced Documents sample that will oxidize to sulfates in the presence of an
oxidizing agent.
2.1 ASTM Standards:
3.1.4 total sulfate, n—inorganic sulfate species actually
D1193 Specification for Reagent Water
present in the sample at the time of analysis with no oxidation
D4052 Test Method for Density, Relative Density, and API
treatment.
Gravity of Liquids by Digital Density Meter
D4057 Practice for Manual Sampling of Petroleum and
4. Summary of Test Method
Petroleum Products
4.1 For total sulfate and chloride, a small volume of an
D4177 Practice for Automatic Sampling of Petroleum and
ethanol sample is directly injected into a suitably configured
Petroleum Products
ion chromatograph in accordance with manufacturer’s recom-
D5827 Test Method for Analysis of Engine Coolant for
mendations for this test method. For potential sulfate, 0.5 mL
Chloride and Other Anions by Ion Chromatography
of 30 % hydrogen peroxide solution is added to 9.5 mL of the
ethanol sample, and then injected into the ion chromatograph.
Ions are separated based on their affinity for exchange sites of
This test method is under the jurisdiction of ASTM Committee D02 on
the resin with respect to the resin’s affinity for the eluent. The
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
suppressor increases the sensitivity of the test method by both
D02.03 on Elemental Analysis.
increasing the conductivity of the analytes and decreasing the
Current edition approved Feb. 1, 2007. Published March 2007. DOI: 10.1520/
D7319-07.
conductivity of the eluent. It also converts the eluent and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
analytes to the corresponding hydrogen forms of anions.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Anions are quantified by integration of their responses com-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. pared with an external calibration curve, and are measured as
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7319–07
FIG. 1 Typical Ion Chromatogram of a Solution Containing 1 mg/L of Various Anions in Water
milligrams/litre, then converted to milligrams/kilograms. The at the lowest possible levels. The use of powder-free gloves is
calibration standards are prepared in an aqueous matrix.
highly recommended to prevent sample contamination.
4.2 Similar methods for chloride and sulfate determinations
can be found inTest MethodD5827 for engine coolant, and for
7. Apparatus
ethanol in Test Method D7328 by ion chromatography with
7.1 Analytical Balance, capable of weighing up to 100 g
aqueous sample injection, and for sulfate only in Test Method
accurately to 0.0001 g.
D7318 by potentiometric lead titration.
7.2 Drying Oven, controlled at 110 6 5°C for drying
sodium sulfate and sodium chloride.
5. Significance and Use
7.3 Desiccator, containing freshly activated silica gel (or
5.1 Sulfates and chlorides can be found in filter plugging
equivalent desiccant) with moisture content indicator.
deposits and fuel injector deposits. The acceptability for use of
7.4 Pipets or Volumetric Transferring Devices, appropri-
the fuel components and the finished fuels depends on the
ately sized Class A glass pipets or their equivalent or variable
sulfate and chloride content.
volume automatic pipets fitted with disposable polypropylene
5.2 Total and potential sulfate and total chloride content, as
tips.
measured by this test method, can be used as one measure of
the acceptability of gasoline components for automotive spark-
7.5 Volumetric Flasks (with Glass Stoppers), ClassAof 10,
ignition engine fuel use.
25, 50, 100, 1000, 2000–cc capacity.
7.5.1 Container, equipped with a closure to prevent ethanol
6. Interferences
evaporation, 1 L (for sample collection).
6.1 Interferences can be caused by substances with similar
7.6 Ion Chromatograph, analytical system with all required
ion chromatographic retention times, especially if they are in
accessories including syringes, columns, suppressor, and de-
high concentration compared to the analyte of interest. Sample
tector.
dilution can be used to minimize or resolve most interference
7.6.1 Injection System, capable of delivering 20 µL with a
problems.
precision better than 1 %, or as recommended for this deter-
6.2 A water dip (system void, negative peak as shown in
mination by the manufacturer.
Fig. 1) can cause interference with some integrators. Usually,
7.6.2 Pumping System, capable of delivering mobile phase
for chloride and sulfate determinations, the water dip should
flows between 0.2 and 2.5 mL/min with a precision better than
not be a problem since the chloride and sulfate peaks are far
2%, or as recommended for this determination by the manu-
away from the water dip.
facturer.
6.3 Given the trace amounts of chloride and sulfate deter-
mined in this test method, interferences can be caused by 7.6.3 Guard Column,forprotectionoftheanalyticalcolumn
contamination of glassware, eluent, reagents, and the like. from strongly retained constituents. Better separations are
Great care must be taken to ensure that contamination is kept obtained with additional theoretical plates.
D7319–07
7.6.4 Anion Separator Column, 100 % solvent compatible 8.4 Suppressor Regenerant Solution for Suppressor—0.1 M
and capable of producing satisfactory analyte (sulfate and sulfuric acid. Carefully add 334 mL of reagent grade sulfuric
chloride) separation (Fig. 1). acid (relative density 1.84) to approximately 500 mL reagent
7.6.5 Anion Suppressor Device, Two different approaches water in a 1-Lvolumetric flask. (Warning—This will generate
(tri-chamber and continuous) were used in the precision study, a very hot solution.Allow it to cool before diluting to 1000 mL
othersmaybeusedaslongastheyproducecomparableresults. volume. Never add water to concentrated acid.) Dilute to 1000
Follow the ion chromatography instrument vendor’s recom- mL with reagent water, and label this solution as 10.0 M
mendations. sulfuric acid. Dilute 10.0 mL of this concentrate to 1000 mL
7.6.5.1 Tri-Chamber Approach, 100 % solvent compatible with reagent water for the final 0.1 M working suppressor
tri-chamber micro packed bed with cation exchange resin (or solution.
equivalent). Suppressor device should simultaneously be on-
NOTE 2—Other volumes of this solution can be prepared using appro-
line continuously chemically regenerated to its hydrogen form
priate ratios of reagents. Follow the specific guidelines for this solution
using any mineral acid providing H+ ion.
from the vendor of the suppressor being used.
7.6.5.2 Continuous Approach, Continuous suppressor mem-
8.5 Sodium Sulfate—anhydrous, reagent grade, 99 % mini-
brane regeneration.
mum purity. (Warning—Do not ingest. Avoid unnecessary
7.6.6 Conductivity Detector, (low volume), temperature
exposure.)
controlled to 0.01°C, capable of at least 0 to 1000 µS/cm on a
8.6 Sodium Chloride—ACS or reagent grade, 99 % mini-
linear scale.
mum purity.
7.6.7 Integrator or Chromatography Data System Software,
capable of measuring peak areas and retention times, and 8.7 Ethanol—denatured with methanol, formula 3A or his-
tological grade ethanol, anhydrous, denatured with ethyl ac-
correcting the data in accordance with the baseline of the
chromatogram. etate, methylisobutyl ketone and hydrocarbon naphtha.
(Warning—Flammable, toxic, and may be harmful or fatal if
7.7 Gloves, powder-free examination type.
ingested or inhaled. Avoid skin contact.)
8. Reagents
8.8 Hydrogen Peroxide—ACS reagent grade, 30 wt % in
8.1 Purity of Reagents—Reagent grade or higher purity
water.
chemicals shall be used for the preparation of all samples,
8.9 Hydrogen Peroxide Solution, 30 %—commercially
standards, eluent, and regenerator solutions. Unless otherwise
available 30 % hydrogen peroxide solution.
indicated, it is intended that all reagents conform to the
specifications of the Committee on Analytical Reagents of the
9. Preparation of Standard Solutions
American Chemical Society, where such specifications are
9.1 Stock Solutions:
available. Other grades may be used, provided it is first
9.1.1 Sulfate Stock Solution, approximately 2000 mg/L—To
ascertained that the reagent is of sufficiently high purity to
ensure dryness, place anhydrous sodium sulfate (5 g) in a
permit its use without lessening the accuracy of the determi-
drying oven at 110°C for at least an hour, cool, and store in a
nation.
desiccator. Accurately weigh 2.96 g anhydrous sodium sulfate
8.2 Purity of Water—Unless otherwise indicated, reference
to the nearest tenth of a milligram and transfer to a 1–L
to water shall be understood to mean reagent water as defined
volumetric flask. Add Type II water to dissolve the sodium
by Type II in Specification D1193. For eluent preparation and
sulfate, and make to volume. Calculate the concentration of
handling, comply with all ion chromatograph instrument and
sulfate in the solution in accordance with Eq 1. Other volumes
column vendor requirements (for example, filtering, degassing,
of stock solution can be prepared using the appropriate ratio of
and the like).
reagents.
8.3 Eluent Buffer Stock Solution—Sodium bicarbonate
(NaHCO ) 1.0 mM and sodium carbonate (Na CO ) 3.2 mM. Stock Sulfate ~mg/L!5~gNa SO !~0.6764!~1000 mg/g!/1 L (1)
2 4
3 2 3
Dissolve 8.4 6 0.0005 g of NaHCO and 33.92 6 0.0005 g of
where:
Na CO in reagent water in a 1-LTypeAvolumetric flask and
2 3
gNa SO = weight in grams of Na SO dissolved in 1 L,
2 4 2 4
dilute to volume. Dilute 10.0 mL of this stock solution to 1 L
and
in a 1-L Type A volumetric flask with degassed reagent water.
0.6764 = weight percent sulfate in Na SO .
2 4
The eluent solution used may be different if other system or
9.1.2 Chloride Stock Solution (approximately 2000 mg/
analytical columns are used.
L)—To ensure dryness, place sodium chloride (5 g) in a drying
NOTE 1—Other volumes of stock solution can be prepared using
oven at 110°C for at least an hour, cool, and store in a
appropriate ratios of reagents. Follow the specific guidelines for this
desiccator. Accurately weigh 3.30 g dried sodium chloride to
solution from the vendor of the column being used. Alternatively, this
the nearest tenth of a milligram and transfer to a 1–L
solution can be purchased from a qualified vendor.
volumetric flask. Add Type II water to dissolve the sodium
chloride and make to volume. Calculate the concentration of
chloride in the solution in accordance with Eq 2. Other
Reagent Chemicals, American Chemical Society Specifications. American
ChemicalSociety,Washington,D.C.Forsuggestionsontestingofreagentsnotlisted
volumes of stock solution can be prepared using the appropri-
by the American Chemical Society, see Annual Standards for Laboratory Chemi-
ate ratio of reagents.
cals, BDH Ltd., Dorset, U.K., and the United States Pharmacopeia and National
Formulatory, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD. Stock Chloride ~mg/L!5~g NaCl!~0.6068!~1000 mg/g!/1 L (2)
D7319–07
TABLE 1 Typical Volumetric Preparation of Chloride and Sulfate Standards in Type II Water
Chloride and Sulfate Standards Chloride Stock Solution, Sulfate Stock Solution,
mg Chloride and Sulfate (each)/1 L water mL mL
-
50 Cl only 25 .
20 10 10
10 5 5
5 2.5 2.5
1 0.5 0.5
0.5 0.25 0.25
0.3 0.15 0.15
chromatogram contain chloride and sulfate peaks with baseline
where:
separation like that shown in Fig. 1. If present in sufficient
g NaCl = weight in grams of NaCl dissolved in 1 L, and
0.6068 = weight percent chloride in NaCl. quantity, other anions can interfere with the chloride and
sulfate measurements.
9.2 Chloride and Sulfate Standards in Water—TypeIIwater
and sulfate and chloride stock solutions are added to a 1–L
NOTE 4—The sample loop volume will vary based on the column
glass volumetric flask in accordance with Table 1 to achieve
capacity, sensitivity, and other factors. Refer to ion chromatography
the desired standard.
equipment manuals and column information for machine-specific details.
9.2.1 Chloride and sulfate stock solutions from 9.1 are
10.1.3 Analytical curves shall be established at only one
added quantitatively into the flask and mixed quantitatively
det
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