Chromatography Principles and Techniques

Vocabulary-style flashcards covering the principles of chromatography, including TLC, Column Chromatography, GC, GCMS, and HPLC based on the lecture material.

Chromatography

A family of separation techniques that depend on the principle that a mixture can be separated if it is dissolved in a solvent (mobile phase) and moves over a solid (stationary phase).

Mobile phase

The resulting solution after a mixture is dissolved in a solvent, which carries the soluble components through the chromatography system.

Stationary phase

The solid or trapped liquid that holds back the components in a mixture that are attracted to it; the more affinity a component has for it, the slower it moves.

Eluent

The solvent used in the moving phase, specifically in the context of column chromatography.

Thin-layer chromatography (TLC)

A development of paper chromatography where the stationary phase is a glass, metal, or plastic sheet coated with silica gel ($SiO_2$) or alumina ($Al_2O_3$).

Locating agent

A chemical sprayed onto a chromatogram to react with colourless components of a mixture to produce coloured compounds.

$R_f$ value

A value used to help identify components, calculated as: $\frac{\text{distance moved by spot}}{\text{distance moved by solvent}}$.

Column chromatography

A technique using a powder, such as silica, alumina, or resin, packed into a narrow tube where eluent is added at the top; it is advantageous for separating and collecting fairly large amounts.

Gas-liquid chromatography (GC) stationary phase

A powder coated with oil, packed into or coated onto the inside of a long capillary tube (up to $100\,m$ long) placed in a variable temperature oven.

Gas-liquid chromatography (GC) mobile phase

An unreactive gas, such as nitrogen or helium, used to carry the sample through the capillary tube.

Retention time

The different time at which a component leaves the gas chromatography column after injection.

GC trace

A graph resulting from gas chromatography where the area under each peak is proportional to the amount of that component.

GCMS

Gas Chromatography-Mass Spectrometry; a system where a mass spectrometer is used as the detector for gas chromatography, identifying compounds by fragmentation pattern or accurate mass.

HPLC

High Pressure (or Performance) Liquid Chromatography; a technique where a mixture is forced through a stationary phase column by a solvent driven by a high-pressure pump.

Chiral stationary phase

A specific type of material used in HPLC that can be used to separate optical isomers.