汽油中烯烃含量检测方案

Application Note 2/3Application NoteDetermination of Olefin Content of Gasoline by Supercritical Fluid Chromatography Determination of Olefin Content of Gasoline by Supercritical FluidChromatography Gasoline is produced by fractional distillationof petroleum at a boiling point between 30℃and 200℃. It contains hydrocarbons such asparaffin， olefin， and aromatics， carbon numbersof which are between 4 and 10. Characterizationof gasoline requires the determination of thecontents of those hydrocarbons. American Society for Testing and Materials (ASTM)announced a method， D6550-00： Standard TestMethod for Determination of Olefin Content ofGasolines by Supercritical-Fluid Chromatography.We have established an analysis system inaccordance with this method. JASCO HPLC 2000 Application Library： http：//www.jascoinc.com/applications Introduction A JASCO HPLC 2000 series was used for the measurement. The system consisted of a PU-2080-CO2liquefied carbon dioxide delivery pump， an AS-2059-SF autosampler， an HV-2080-01 column switchingvalve (2 sets)， a CO-2060 column oven， a flame ionization detector， a BP-2080 back-pressure regulator， andChromNAV data system. Separation columns were a SFCpak SIL PA silica gel column (4.6 mm IDx250 mmL， 5 mm) and a SFCpakSIL AGS silver-coated silica gel column (4.6 mm IDx50 mmL， 5 um). The operation for the measurement was carried out as follows： 1. Connect the silica gel and silver-coated silica gel columns， and deliver liquefied carbon dioxide. 2. Inject sample to elute paraffin first. 3. Disconnect the silver-coated silica gel column from the flow path by using the column switching valves，and elute aromatics adsorbed on the silica gel column. By using the column switching valves， disconnectthe silica gel column and connect the silver-coated silica gel column again， and elute olefin adsorbed on thesilver-coated silica gel column. Results and Discussion Figure 1 illustrates a schematic of the system. Switching the two columns allowed separation of paraffin，aromatics， and olefin. Effluent from the columns was divided by a splitter and a portion of the effluent wasintroduced into the FID detector. Figure 2. SFC chromatogram ofstandard mixture. Peaks： 1=hexadecane.2=toluene， 3=octadecene.Conditions：separation column=SFCpak SIL-PA(4.6mmlDx250 mmL， 5 pm) and SFCpakSIL PA-AGS (4.6 mmlD x50 mmL，5 um)，flow rate of liquefied carbon dioxide=2mL/min， injection volume=1 mL Figure 3 shows a SFC chromatogram obtained by direct injection of commercially available gasoline. Theolefin content of the gasoline was quantified to be 21.1% by comparing peak areas. Figure 3. SFC chromatogram ofcommercially available gasoline. Thechromatographic conditions are thesame as in Figure 2. JASCO INC.Mary's Court， Easton， MD USATel： ( Fax： (