Cation-exchange chromatography is a technique used to separate ions and polar molecules based on their affinity to the ion exchanger. In this technique, the stationary phase contains negatively charged groups that attract and retain positively charged cations.
The options provided in the question are:
- DEAE-cellulose
- CM-cellulose
- Sephadex G-50
- Heparin-Sepharose
Let us evaluate each option to determine the correct stationary phase for a cation-exchange chromatography:
- DEAE-cellulose: This is a diethylaminoethyl cellulose, which is an anion exchanger. It contains a positively charged group and is used for anion-exchange chromatography, not suitable for cation-exchange.
- CM-cellulose: This is a carboxymethyl cellulose, which is a cation exchanger. It contains negatively charged carboxylate groups that can attract cations. Therefore, this is the correct stationary phase for cation-exchange chromatography.
- Sephadex G-50: This is a gel filtration media, primarily used for size-exclusion chromatography, not for ion-exchange chromatography.
- Heparin-Sepharose: This type of matrix is often used for affinity chromatography, aimed at specific interactions, and not typically used as a cation exchanger.
From the above analysis, it is clear that CM-cellulose is the correct choice for the stationary phase in cation-exchange chromatography due to its negatively charged groups that can bind cations effectively.