How does polarity affect chromatography?

Question

Owen Ambrose · Accepted Answer

The solvent used for chromatography will be selected based on the polarity of the substances in the mixture you want to separate.

Chromatography is a method for separating mixtures based on differences in the speed at which they migrate over or through a stationary phase. This will separate complex mixtures of chemicals or proteins into their various different components.

Polarity has a huge affect on how attracted a chemical is to other substances. Some molecules have a positively charged side and a negatively charged side. For example, the positive side is attracted to the negative side of another molecule (opposites attract). The larger the charge difference, the more polar a molecule is.

You will find that as you increase the polarity of the solvent, all the components of the mixture move faster during your chromatography experiment.

Here is a video which shows a paper chromatography experiment which was conducted to separate the pigments found in a black overhead marker. The different colors of pigments have different solubilities based on their polarity. The blue pigment has a greater solubility in water so it moves faster (goes higher) through the chromatography paper. The yellow pigment is less soluble so it moves more slowly.

Video from: Noel Pauller

Hope this helps!

Serenity Allen · Answer

undefined Polarity affects chromatography by influencing the interaction between the mobile phase (solvent) and the stationary phase (adsorbent). Compounds with similar polarity to the stationary phase will be retained longer, while those with lower polarity will move through the column faster. This separation is based on the principle that like dissolves like.