Analytical techniques Flashcards
Chromatography
Separation of mixture of compounds using mobile phase based on different attraction to the stationary phase
Stationary phase
A non-moving component, typically a solid or liquid coated on the solid support, that interacts with the sample as they are carried by mobile phase
Mobile phase
A mobile component, typically a liquid or gas that transports the sample within/ across the stationary phase
What stationary phase is used for TLC (thin-layer chromatography)
Silica gel (SiO2) or alumina (Al2O3)
Stationary phase is polar
What mobile phase is used for TLC (thin-layer chromatography)
Organic solvent (e.g ethyl ethanoate, dichloromethane)
In TLC (thin-layer chromatography), polar substances move slower because
they have stronger attraction to the stationary phase
Order of polarity
Carboxylic acids > amides > alcohols > amines > carbonyl > esters > alkanes
Formula Rf
distance of sample from baseline / distance of solvent front from baseline
What stationary phase is used in GLC (gas-liquid chromatography)
Unreactive gas (N2, He, Ar)
What mobile phase is used in GLC (gas-liquid chromatography)
A high boiling point, non-pilar liquid (on the solid support)
In GLC (gas liquid chromatography) non-polar substances move slower because
they have stronger attraction to the non-polar stationary phase
Retention time
Time between injection and detection of sample
