chromatography 2

Question 1

If you were running aspirin through a reverse phase column with an aqueous mobile phase, what would you expect to happen to the elution time if you increased the pH (made it more basic)?

Answer 1

Become ionised and therefore more polar. Will stay longer in mobile phase and elute faster.

Question 2

explain Liquid Chromatography-Mass Spectroscopy (LCMS)

Answer 2

Hyphenated technique – Can separate and. The use of HPLC/MS has the advantage of aiding in the structural identification of the separated analytes.

Question 3

explain Gas chromatography

Answer 3

The mobile phase in gas chromatography is a gas, e.g. helium,
The stationary phase can be either liquid adsorbed onto a solid (most common – called GLC), or organic species bonded to a solid surface (older less used technique). Separation mainly based on the volatility of the substances in the mixture.

Question 4

what compounds can be separated by gas chromatography?

Answer 4

Compounds with reasonable volatility and heat stability can be separated by gas chromatography. Good for small organic molecules.

Question 5

_____________is the most widely used gas chromatography technique.

Answer 5

Gas-liquid chromatography

Question 6

explain Gas-liquid chromatography

Answer 6

The mobile phase is a gas and the stationary phase is a liquid that is retained on the surface of an inert solid by adsorption or chemical bonding.

Question 7

in Gas-liquid chromatography, the Separation of the components is dependant on two factors?

Answer 7

The volatility of the component at column temperature

The polarity (solubility) of the component in the stationary phase