1.4 Chromatography

• Thin Layer Chromatography (TLC) 

  A is more/less polar than B. A more/less polar compound will adsorb more/less strongly onto the polar/non-polar stationary phase and hence travel less/more from the origin. Since A traveled less/more up/down the TLC plate compared to B, A is more/less polar.
• Column Chromatography (for gas & liquid) 

  A more polar/non-polar compound will adsorb less/more strongly onto the non-polar/polar stationary phase, and hence travel slower/faster out of the column. Since A has a higher/lower retention time (time to exit column), A is more/less polar.
• Ion Exchange Chromatography

  Anion Exchange = separates -

  Cation exchange = separate +
• Retardation Factor = distance unknown moves / distance the solvent front moves (mobile phase)
• Ion Exchange Chromatography

  A more low/high charge density compound will adsorb less/more strongly onto the positively/negatively charged resin, and hence travel slower/faster out of the resin. Since A has a higher/lower charge density of __ compared to B of __, A has a shorter/longer retention time.
• Since every compound has a unique retention time this means a different compound has been used in the imitation.
• As A travels through the column, its components of varying polarity would be adsorbed to the stationary phase at different strengths and hence and travel through the column at a different pace. Ultimately the components of the rose oil would be separated.
• The cation-exchange column features a negatively charged resin. Thus, as the A2+ travels through the column, its positive charge will adsorb to the negatively charged resin. Since A2+ has a higher charge density of 2+ compared to the B+ ions, cation exchange would occur with the following equilibrium.

  • LCP, decreases concentration of A2+