Loading

Module 1: Cromatografía

Apuntes
Study Reminders
Support
Text Version

Papel y cromatografía en capa fina

Set your study reminders

We will email you at these times to remind you to study.
  • Monday

    -

    7am

    +

    Tuesday

    -

    7am

    +

    Wednesday

    -

    7am

    +

    Thursday

    -

    7am

    +

    Friday

    -

    7am

    +

    Saturday

    -

    7am

    +

    Sunday

    -

    7am

    +

XSIQ
*

Chemistry - Paper and thin-layer chromatography

Paper and thin-layer chromatography

In paper chromatography, the stationary phase is a piece of high-quality
absorbent paper, similar to filter paper.

In thin-layer chromatography, the stationary phase is a thin layer of a
fine powder, such as alumina, spread on a glass or plastic plate.

A small spot of the substance being analysed is placed on the paper or
thin layer. The paper or material supporting the thin layer is then placed
in a shallow dish of solvent. The solvent moves up the paper or thin layer.

The different components of a mixture will move up the paper or thin layer
at different rates - depending on the relative strength of their attraction
to the stationary and mobile phases - and produce a chromatogram. In the
chromatogram shown here, component A was more strongly attracted to the
mobile phase than was component B. Component B was more strongly attracted
to the stationary phase than was component A.

Rf values are determined according to

The main application of paper and thin-layer chromatography is in
qualitative analysis, i.e. to check the presence of a particular compound
in a mixture

However, an_ R_f value alone cannot tell us anything.

Reference to a file of _ R_f values obtained under the same experimental
conditions is an effective way of identifying a particular compound.
Alternatively, if the identity of the compound is suspected, a chromatogram
of the pure compound under the same experimental conditions should give the
same _ R_f value.

Previous | Next