Created with MindGenius Business 2005Created with MindGenius Business 2005®®

Supercritical Fluid Supercritical Fluid Chromatography Chromatography

Supercritical fluids Occur above a critical temperature

and a critical pressure, Show both gaseous and liquid

properties for Density Diffusion coefficient and Viscosity

Are very good solvents Are frequently cheap, innocuous, non-

toxic Can easily be removed by evaporation Give GC/LC hybrid behaviour – make

great mobile phasesSFC is particularly useful for analytes that are: Non-volatile Easily thermally-decomposed and/or Unsuitable for spectroscopic or electrochemical detectionand thus cannot be analysed by GC or HPLC

Source:http://www.selectscience.net/products/Source:http://www.selectscience.net/products/analytical+preparative-sfc-instrument/?analytical+preparative-sfc-instrument/?

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Created with MindGenius Business 2005Created with MindGenius Business 2005®®

Supercritical Fluid Supercritical Fluid Chromatography Chromatography

Mobile:Stationary phase equilibriumDependent on partition, strongly influenced by solvation power of the supercritical fluid

Instrumentation: modified HPLC equipment: Thermostatted column oven Back-pressure device between column and detector (narrow capillary at end of column) Detection may be conducted in gas phase

Mobile Phase Any supercritical fluid (commonly CO2, N2O, NH3, 1-Butane)CO2 becomes supercritical at T>31ºC, P>7400KPa

Stationary Phase Variety, generally “cannibalised” from HPLC or GC May be packed (like HPLC) Or open-tubular siloxane coated (like GC)

Created with MindGenius Business 2005Created with MindGenius Business 2005®®

Supercritical Fluid Supercritical Fluid Chromatography Chromatography

Retention and Resolution Quicker than HPLC N similar to that for GC Suffers from band broadening (diffusion) like GC

Optimisation: Pressure gives solvent power and thus RT . e.g.(Hexadecane at 70atm RT=25min, 90 atm RT=5min). May use gradient or isobaric elution. Temperature (for similar reasons) Organic modifiers (e.g. MeOH)

Detection Often uses HPLC detectors (UV etc) SFC allows easy interface with MS or IR Also allows use of Flame Ionisation Detector (FID) Eluent easily removed for further analysis

ApplicationsWide range including: Drugs, foods, pesticides, polymers, surfactants….