Chromatography Flashcards
Stationary phase
stays put, solid with large SA
mobile phase
moves, liquid or gas
eluting power
effectiveness of solvent in displacing solutes from an adsorber
order in terms of decreasing eluting power: water, benzene, ethanol, hexane, methanol, propanol
- water
- methanol
- ethanol
- propanol
- benzene
- hexane
how does solvent move up TLC plate
capillary action
how to develop TLC results
- UV
- ninhydrin
retention time (tR)
time taken for compound to move through column
tM
time taken for mobile phase to pass through column
column efficiency
measure of broadening of sample peak / number of theoretical plates
theoretical plate model
column made of imaginary plates, equilibration occurs in each plate
resolution value
greater than 1.5
parts of HPLC
detector, column, autosampler, degasser, pump, solvent reservoir,
ideal HPLC detector
- unaffected by changes in ambient temp or mobile phase composition
- should not contribute to peak broadening
what causes ghost peaks in GC
deposited analyte is carried back into inlet liner when blackflashing injection is made
advantages and disadvantages of splitless injections
+ easy to use, protects column, suitable for trace analysis
- complicated, can cause thermal decomposition of components, sample discrimination
Reverse-phase chromatography
- SP non-polar
- MP polar
- polar analytes eluted first
Normal phase chromatography
- SP polar
- MP non-polar
- non-polar analytes eluted first
