chromatography 

• high performance liquid chromatography HPLC

• used for separating high boiling point liquids and solids in solution

• operation

  • the stationary phase is contained inside a metal tube or column

  • in HPLC the mobile phase is a liquid

  • the samples to be separated are injected into the coloum and then carried through it by the mobile phase.the substances interact with the stationary phase in the column

  • some components of the sample will be restarted by the stationary phase more than others and so will take longer to move down the coloum.at the end of the column there is a detector the small amounts of substances as they emerge from the end of the column

  • the detector produces a signal that is in proportion to the amount of substance present

  • the signal is used to generate a computerised output

  • peak is retention - area under the peak proportional to amount of substance

gas liquid chromatography

• used to separate mixtures of substances that are volatile (have low boiling points)

• the stationary phase is a liquid attached to an inert silica base packed into a column

• the column is contained within an oven

• the mobile phase is an inert gas,usually helium 6