29.1 Chromatography Flashcards
what is the stationary phase?
the phase which does not move
solid
what is the mobile phase
the phase which moves
liquid or gas
what substance are TLC plates made out of?
silica
is solid adsorbent
what is the stationary phase in TLC?
the silica
what is adsorption?
attraction between substance and stationary phase
a substance which is STRONGLY ADSORBED
will move slowly
so smaller Rf value
a substance which is WEAKLY ADSORBED
will move quickly
so larger Rf value
the MORE POLAR a substance is
the STRONGER it is adsorbed by the stationary phase
so will move slowly
so smaller Rf value
Rf equation
distance moved by solvent front
how can Rf values be used to identify compounds?
they are compared with known Rf values
what can be told from a gas chromatogram?
retention time
peak integration
what does retention time tell you?
used to identify components in a sample by comparing times with known values
what do peak integrations tell you?
to determine the concentration of components
what is the retention time?
time for the compound in GC to leave the column
