13 Chromatography Flashcards
3 main chromatography techniques
TLC
GC
HPLC
Define chromatography
Techniques used to seperate components of a mixture
Factors that make chromatography possible
- different types of polar groups
- # of charged and polar groups present
- molecular weight
- geometry
- ## positions land # of bonds
What is the mobile phase
The solvent or gas which flows through and caries components across stationary phase.
What is the stationary phase
Solid or liquid which is supported
What is TLC
Thin layer chromatography has a horizontal thin absorbant stationary phase bonded to glass or plastic support. Material consists of microscopic plates which increases surface area to better seperste components.
Solvent mobile phase moving due to capillary action.
particles that are more attracted to the stationary phase move slowest. Those more attracted to mobile phase move faster as they are interacting less with stationary phase.
What is retardation factor?
distance component travelled from origin
R F= ——————————————
Distance the solvent front travelled from the origin
Must be less than one
Column chromatography
Much like TLC, but Sample is deposited on a cylinder of absorbent. solvent is continually applied with pressure until components. Completely drain through. Components can be separated and collected in different containers which is called the eluent.
What is a gas chromatography?
Used for small organic molecules, which can with stand high temperatures e.g. blood alcohol levels.
Sample is injected into machine and gas (mobile phase) pushes it along a thin, long column (stationary phase) particles which absorb onto the stationary phase, the least come out first larger particles and those that absorb onto the stationary phase most come out last.
Absorb vs desorb
Desorb is the release of a substance which was used once absorbed to a surface.
Define affinities
What is retention time
Time taken for components to pass through stationary phase
Used to identify components
Quantitative analysis
Amount/concentration
What is a standard solution
One in which we know the quantitative value or concentration of sample is accurately known
Qualitative analysis
Different components present
Calibration curve
