Intermediate Topic 906 of 1102 Analytical, Lab & Spectroscopy
Column Chromatography
Mixtures separated as they pass through a packed stationary phase.
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In-depth explanation of Column Chromatography
Column chromatography purifies larger quantities of material by loading a mixture onto the top of a glass column packed with a stationary phase such as silica gel or alumina. A solvent, the eluent, is passed through the column under gravity or pressure, and components move down at different rates according to their adsorption and solubility. The separated bands are collected as successive fractions, which are checked by TLC to find those containing the pure compound. The eluent polarity is often increased during the run in a technique called gradient elution, which speeds up strongly retained compounds. The method scales from milligrams to many grams and is a standard tool for purifying reaction products.
Going deeper: Column Chromatography
Key ideas: Use roughly 30 to 100 g of silica per gram of sample, pack as a slurry without air gaps, and load the sample in the smallest possible volume. Pick an eluent that gives the product Rf near 0.3 on TLC. Never let the solvent level fall below the top of the silica. Flash chromatography uses air pressure to speed the run to minutes.
Common mistakes and connections: Cracks or bubbles in the packing cause channeling and poor separation, and overloading broadens bands until they overlap. Starting with a solvent that is too polar washes everything out together. Students sometimes forget to check all fractions by TLC before combining. Related to TLC, polarity, adsorption and HPLC, which is a high-pressure automated version.
Visualization of Column Chromatography
Fractions collected from a silica column show bands eluting one after another; checking fractions by TLC tells which contain the pure compound. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Plant pigments such as chlorophylls and carotenoids can be separated on a silica column.
Frequently asked questions about Column Chromatography
What is Column Chromatography?
Mixtures separated as they pass through a packed stationary phase.
Is Column Chromatography a beginner, intermediate or advanced topic?
Column Chromatography is a intermediate topic in Analytical, Lab & Spectroscopy. It builds on the vocabulary of beginner topics in this area.
What should I learn before Column Chromatography?
Study these earlier topics in Analytical, Lab & Spectroscopy first: Solvent Extraction, Paper Chromatography, Thin Layer Chromatography.
What comes after Column Chromatography?
The next topics in Analytical, Lab & Spectroscopy are Gas Chromatography and HPLC.
Can I practise Column Chromatography with quizzes?
Yes. The interactive lesson includes a self-check question on Column Chromatography, and the Analytical, Lab & Spectroscopy quiz draws on every topic in this area.
Where Column Chromatography fits in Analytical, Lab & Spectroscopy
Column Chromatography is topic 30 of 99 in Analytical, Lab & Spectroscopy.