intrumentation and applications of super critical fluid chromatography

1. SUPER CRITICAL FLUID
CHROMATOGRAPHY
DINESH K
M PHARM PHARMACOLOGY
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3. CONTENTS
Introduction
Definition
Principle
Instrumentation
Advantages
Disadvantages
Applications
Conclusion
References
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4. WHAT IS SUPER CRITICAL FLUID?
• SCF can be described as a fluid obtained by heating above the
critical temperature and compressing above the critical
pressure.
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6. For every substance, there is a temperature above which it can
no longer exist as a liquid, no matter how much pressure is
applied. Likewise, there is a pressure above which the
substance can no longer exist as a gas no matter how high the
temperature is raised.
 These points are called critical temperature and critical
pressure respectively.
 Above this point,the substance acts as a supercritical fluid .
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7. • A supercritical fluid is any substance at a temperature and pressure above
its critical point.
• It can diffuse through solids like a gas, and dissolve materials like a
liquid.
• Additionally, close to the critical point, small changes in pressure or
temperature result in large changes in density, allowing many properties
to be "tuned".
• Supercritical fluids are suitable as a substitute for organic solvents in a
range of industrial and laboratory processes.
• In the Supercritical region the substance is neither a gas nor a liquid – it is
a fluid that has properties of both.
• There are no sharp boundaries between gas and liquid.
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8. COMPARISON PROPERTIES OF GAS, SCF AND LIQUID.
Property Gas (STP) SCF Liquid
Density (g/cm 3 ) (0.6-2) x 10 -3 0.2-0.5 0.6-2
Diffusion coefficient
(cm 2 /s)
(1-4) x 10 -1 10 -3 x 10 - 4 (0.2-2) x 10 -5
Viscosity (G Cm -1 s -1 ) (1-4) x 10 - 4 (1-3) x 10 - 4 4 (0.2-3) x 10 -2
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9. INTRODUCTION
 Supercritical fluid chromatography(SFC) was first proposed in
1958 by J. Lovelock.
 First used in1962 by Klesper.
 It is used for the analysis & purification of low moderate
molecular weight, thermally liable molecules.
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10. DEFINITION
A supercritical fluid chromatography is a material that can be
either liquid or gas used in state above critical temperature or
critical pressure where gases or liquid can co exist.
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11. PRINCIPLE
• Principles are similar to those of High Performance Liquid
Chromatography (HPLC), however SFC typically utilizes
carbon dioxide as the mobile phase; therefore the entire
chromatographic flow path must be pressurized. Because the
supercritical phase represents a state in which liquid and gas
properties converge, supercritical fluid chromatography is
sometimes called "convergence chromatography."
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12. INSTRUMENTATION
• Stationary phase
• Mobile phase
• Pumps
• Injectors
• Restrictors
• Micropressure
• Ovens
• Columns
• Detector
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14. STATIONARY PHASE
 Both packed and open tubular columns are used.
 Packed columns can provide more theoretical plates and
handle large volume than open tubular columns.
 Because of low viscosity of super critical media.
 The column length is 10 to 20m. and inside the diameter is 50
to 100mm common in open tubular columns.
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15. CONT..
 For difficult separation column 60m (or) large have been used.
 Packed column usually made up of stainless steel,10 to 25cm.
 More than 100,000 plates have been achieved in plate column.
 Many of column coating used in LC have been applied to SFC
as well.
 Typically their are polysiloxane chemically bounded wall of
capillary tubing .
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16. MOBILE PHASE
The mobile phase is composed primarily of super critical
carbon dioxide, but since CO2 on its own is too non-polar to
effectively elute many analytes, co-solvents are added to
modify the mobile phase polarity.
 Co-solvents are typically simple alcohols like methanol,
ethanol or isopropyl alcohol. Other solvents such as
acetonitrile, chloroform or ethyl acetate can be used as
modifiers.
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17. CONTI..,
• Modify valves for analytes ,ethane, pentane, diethyl ether,
ammonia.
• Pressure maintained is 72.9 atm, temperature is 35ºc.
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18. PUMPS
• Here mainly flow control is necessary so syringe pumps are
used for capillary SFC for consistent pressure and for packed
columns for easier blending of the mobile phase or introduction
of modifier fluids reciprocating pumps are used.
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19. INJECTORS
• In capillary SFC small sample should be quickly injected into
the column and so pneumatically driven valves are used.
• For packed SFC a typical injection valve is commonly used.
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21. RESTRICTORS
This is a device, which is used to maintain desired pressure in the
column by
a pressure-adjustable diaphragm or
controlled nozzle
so that the same column-outlet pressure is maintained irrespective of the
mobile phase pump flow rate.
 It keeps the mobile phase supercritical throughout the separation and
often must be heated to prevent clogging.
 The pressure restrictor is placed either after the detector or at the end of
the column.
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22. OVENS AND MICRO PROCESSOR
• Conventional GAS chromatography & liquid chromatography
ovens are used.
Microprocessor
• The commercial instruments for SFC are ordinarily equipped
with one or more microprocessors to control such variables as
pumping pressures, oven temperature and detector
performance.
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23. COLUMNS
Two types of analytical columns are used in SFC
packed and
 capillary.
 Packed columns contain small deactivated substances to
which the stationary phase adheres. These are conventionally
stainless steel.
 Capillary columns are open tubular columns made of fused
silica which have small internal diameter.
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25. MODIFIERS
• CO 2 is not a very good solvent for high molecular weight,ionic and
polar analytes.
• This can be overcome by adding a small portion of a second fluid called
modifier fluid.
• This is generally an organic solvent, which is completely miscible with
carbon dioxide, methanol, acetonitrile, ethanol and 1-propanol.
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26. DETECTORS
Flame ionization detectors
Flame photometry detector,
 liquid-phase detectors like refractive
index detector,
 ultraviolet-visible spectrophotometric detectors
 light scattering detectors
These types of detectors have been employed for SFC.
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27. ADVANTAGES
SFC is emerging as a separation technique that is superior to
both gas chromatography and liquid chromatography for
analysis of thermal liable or non volatile compounds.
 Low viscosity.
 Lower operating temperature.
 High diffusion co efficient.
 High resolution at low temperature.
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28. DISADVANTAGES
SFC is pressure operating conditions.
High-pressure vessels are expensive and bulky.
 Maintaining pressure in SFC is difficult.
 supercritical fluids are highly compressible and their physical
properties change with pressure.
 Cleaning will be time consuming.
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29. APPLICATIONS
SFC is used in industry primarily for separation of chiral
molecules.
 SFC now commonly used for chiral separation and
purification in the pharmaceutical industry.
 SFC technique has been applied to wide verity of materials,
including natural products, drugs, food and polymers etc.
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30. CONCLUSION
• In overall ranking of chromatographic techniques it can be
judges that SFC falls somewhere between HPLC and GC.
• In field of pharmaceutical chemistry and bio analytical
applications SFC gained its applications.
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31. REFERENCES
• Muneo Saito (2008), [pdf Supercritical Fluid Chromatography:
A New Technology?], Packed Column SFC 2008, Switzerland.
• Super critical fluid chromatography “Skoog” instrumental
analysis pg: 935 to 940.
• Supplement and Cumulative Index, Edited by Bryant W.
Rossiter and Roger C. Baetzold. Physical Methods of
Chemistry Series, 2nd ed., Vol. X. ISBN 0-471-57086-9 0 1993
JohnWiley & Sons, Inc.
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