Pharmacognosy 1. ppt.

1. Partition Chromatography
• Based on a thin film formed on
the surface of a solid support by a
liquid stationary phase.
• Solute equilibrates between the
mobile phase and the stationary
liquid.
• Partition - based on the relative
solubility of analyte in mobile
and stationary phases
 Reversed phase chromatography
(GC, HPLC)
 Paper chromatography
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2. Partition Chromatography
 If both the stationary and the mobile phase are liquid, then the
partition chromatography is also known as Liquid-Liquid
Chromatography (LLC).
 If the mobile phrase is gas then it is called Gas-liquid
Chromatography (GLC).
 In LLC
 the two phase are liquids.
 The two liquids must be immiscible.
 The stationary liquid is present as thin film on an inert solid
support
 Separation occurs due to the difference in partition
coefficients of solutes between the two liquids.
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3. Selection of the mobile phase
 The liquid stationary & mobile phases should have a
 considerable difference between their
solvent strength parameters (polarity index).
 Pure water > Methanol > Ethanol > Propanol >
Acetone > Ethyl acetate> Ether > Chloroform >
Dichloromethane >Benzene > Toluene > Carbon
tetrachloride > Cyclohexane > Hexane > Pentane.
e.g. if the stationary phase is water (polar),
pentane/hexane (non-polar) would be the
eluent/mobile phase of choice.
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4. The mobile phase during LLC separation is usually
 saturated with the stationary phase to overcome "stripping"
(washing of the stationary phase from the column by the mobile
phase).
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5. Gel Permeation Chromatography (GPC)
This type is also known as:
Size Exclusion Chromatography (SEC)
Molecular Exclusion Chromatography (MEC)
Molecular Sieve Chromatography (MSC)
Gel Filtration Chromatography (GFC)
Gel Chromatography
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6. Molecular Exclusion Chromatography
 Separation based on
size
 Molecular weight (10%
difference in Mwt)
 Small molecules get
trapped in pores & take
longer to get out
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8.  Separation mechanism
 Based on difference between the solutes molecular weights
(10% Mwt difference b/n the separating compounds )
 Molecules will distribute themselves outside & inside the pores
according to their size.
 Larger are excluded, medium sized enter half-way & smallest
permeate all the way.
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9. Ion Exchange Chromatography
 Separation of either cations or
anions
 Separation based on relative
strength of ionic bond
 Anion exchanger has cations on
surface
 Cation exchanger has anions on
surface
 It works for ionic compounds
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11.  Very selective
 Specific binding site is used to
concentrate analyte on column
 Unique biological specificity of
the sample and the ligand
interaction is utilized for the
separation
 Used a lot in biological
applications
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Affinity Chromatography
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