Analytical QC II
Wednesday, 28 October 2020 12:05
Analytical Techniques & Quality Control Part 2 Chromatographic Analyt
Techniques
Analytical Chromatography
•Analyse mixtures of substances
• Advantage:
•“Chrome” = colour, “graphein” = to write colour writing
•Separation based on differences in chemical and physical properties
•Several different types of chromatography, e.g. thin layer chromatography (TLC), gas-
liquid chromatography (GLC), high-performance liquid chromatography (HPLC)
Chromatography - Separation Mechanisms
• Separation based on interactions between:
• analyte
• stationary phase
• mobile phase – active or passive
• Adsorption
• intermolecular interactions e.g. electrostatic, hydrogen bonding, dipole-dipole
(solid/liquid)
•Dominant mechanism for normal phase TLC
• Solubility – partition (liquid/liquid)
• Dominant mechanism for reverse phase HPLC and GC
• Molecular shape - affinity, chiral
• Molecular size - size exclusion
Analytical Chromatography
•Distribution of the compounds to be separated between two immiscible phases
•The mobile phase:
•The stationary phase:
Chromatography
• Could we perform millions of extractions with minimal volumes of solvents?
• Replacing one of the phases with a solid (‘stationary phase’) and running the second
phase (‘mobile phase’) over it!
,tical
-
, Chromatography
Planar techniques (capillary action):
• Paper chromatography
• TLC
Column techniques (gravity or pressure):
• HPLC
• GLC
First stage: separation based upon the movement of an analyte between:
• stationary phase
• mobile phase
Second stage: detection of components
• Components in a mixture travel at different rates
Basic principle: like dissolves like
• If a silica gel (normal phase) coated plate is used with a non-polar solvent (hexane,
chloroform), polar compounds in the sample will stick longer to the polar stationary pha
• On the contrary, if an octadecylsilica (reverse phase) is used with a polar solvent (wat
alcohols), apolar compounds in the sample will stick longer to the apolar stationary pha
Wednesday, 28 October 2020 12:05
Analytical Techniques & Quality Control Part 2 Chromatographic Analyt
Techniques
Analytical Chromatography
•Analyse mixtures of substances
• Advantage:
•“Chrome” = colour, “graphein” = to write colour writing
•Separation based on differences in chemical and physical properties
•Several different types of chromatography, e.g. thin layer chromatography (TLC), gas-
liquid chromatography (GLC), high-performance liquid chromatography (HPLC)
Chromatography - Separation Mechanisms
• Separation based on interactions between:
• analyte
• stationary phase
• mobile phase – active or passive
• Adsorption
• intermolecular interactions e.g. electrostatic, hydrogen bonding, dipole-dipole
(solid/liquid)
•Dominant mechanism for normal phase TLC
• Solubility – partition (liquid/liquid)
• Dominant mechanism for reverse phase HPLC and GC
• Molecular shape - affinity, chiral
• Molecular size - size exclusion
Analytical Chromatography
•Distribution of the compounds to be separated between two immiscible phases
•The mobile phase:
•The stationary phase:
Chromatography
• Could we perform millions of extractions with minimal volumes of solvents?
• Replacing one of the phases with a solid (‘stationary phase’) and running the second
phase (‘mobile phase’) over it!
,tical
-
, Chromatography
Planar techniques (capillary action):
• Paper chromatography
• TLC
Column techniques (gravity or pressure):
• HPLC
• GLC
First stage: separation based upon the movement of an analyte between:
• stationary phase
• mobile phase
Second stage: detection of components
• Components in a mixture travel at different rates
Basic principle: like dissolves like
• If a silica gel (normal phase) coated plate is used with a non-polar solvent (hexane,
chloroform), polar compounds in the sample will stick longer to the polar stationary pha
• On the contrary, if an octadecylsilica (reverse phase) is used with a polar solvent (wat
alcohols), apolar compounds in the sample will stick longer to the apolar stationary pha
