Intermediate Topic 861 of 1102 Organic Chemistry
Chromatography
Separation based on differing distribution between mobile and stationary phases.
In-depth explanation of Chromatography
Chromatography separates the components of a mixture because each component distributes differently between a mobile phase and a stationary phase, so the components travel at different rates. Compounds that bind strongly to the stationary phase move more slowly. The retention factor, Rf, is the distance travelled by a spot divided by the distance travelled by the solvent front, and it is characteristic of a compound under given conditions. Common types include paper, thin-layer, column, gas and high-performance liquid chromatography.
Going deeper: Chromatography
Key ideas: Separation by differential distribution between stationary and mobile phases. Retention factor Rf equals distance moved by spot over distance moved by solvent front, always below 1 and depending on solvent and plate. Types: thin layer (TLC, silica or alumina), column, paper, gas (GC) and HPLC. More polar compounds stick more to polar silica, so they travel shorter distances.
Common mistakes and connections: Students measure Rf to the wrong part of the spot or from the solvent line instead of the baseline. Another mistake is expecting the same Rf in a different solvent. Spots may need UV, iodine or ninhydrin to visualise. Links to polarity, purification and amino acid or dye identification.
Visualization of Chromatography
Components of a mixture spend different times on the column, so each emerges as its own peak with its own retention time. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Plant pigments separate into distinct coloured spots on a thin-layer chromatography plate, each with its own Rf value.
Frequently asked questions about Chromatography
What is Chromatography?
Separation based on differing distribution between mobile and stationary phases.
Is Chromatography a beginner, intermediate or advanced topic?
Chromatography is a intermediate topic in Organic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Chromatography?
Study these earlier topics in Organic Chemistry first: Qualitative Organic Tests, Iodoform Reaction, Purification of Organic Compounds.
What comes after Chromatography?
The next topics in Organic Chemistry are Elemental Analysis and Degree of Unsaturation.
Can I practise Chromatography with quizzes?
Yes. The interactive lesson includes a self-check question on Chromatography, and the Organic Chemistry quiz draws on every topic in this area.
Where Chromatography fits in Organic Chemistry
Chromatography is topic 133 of 148 in Organic Chemistry.