EXPLANATION
Sulfates and chlorides can be found in filter plugging deposits and fuel injector deposits. The acceptability for use of the fuel components and the finished fuels depends on the sulfate and chloride content. The method is applicable to hydrous and anhydrous denatured ethanol to be used in motor fuel applications. It is intended for the analysis of ethanol samples containing between 1.0 and 20 mg/kg of total or potential inorganic sulfate and 1.0 to 50 mg/kg of inorganic chloride.
This method can measure between 0.55 and 20 mg/kg of total inorganic sulfate, 4.0 to 20 mg/kg of potential inorganic sulfate, and 0.75 to 50 mg/kg of total inorganic chloride.
TEST SUMMARY
For total inorganic sulfate and chloride, a small volume of a sample is evaporated to dryness and reconstituted to the initial sample volume with deionized water, and injected into an ion chromatograph consisting of appropriate ion exchange columns, suppressor and a conductivity detector. For potential sulfate, the dried residue is reconstituted with 0.90% hydrogen peroxide solution in water, and injected into an ion chromatograph.
Similar methods for chloride and sulfate determinations can be found in Test Method D5827 for engine coolant and for ethanol in ISO/CEN 15492.
Interferences - Interferences can be caused by substances with similar ion chromatographic retention times, especially if they are in high concentration compared to the analyte of interest. Sample dilution can be used to minimize or resolve most interference problems.
TEST PRECISION
where X is the average of two determinations.
Since no generally accepted reference materials are available for this analysis, no statement regarding the bias of this test method can be made.