Summary
Separates mixtures, such as pigments, by their different movement through a stationary phase.
In depth
Paper and thin-layer chromatography separate pigments by solubility and attraction to the medium; Rf = distance moved by solute / distance moved by solvent. Gas and liquid chromatography are used for analysis.
The stationary phase is paper or silica; the mobile phase is solvent. Compounds travel according to solubility and affinity. Rf values are characteristic.
Remember: mark the origin in pencil, not ink.
Chromatography separates the components of a mixture based on differences in how they distribute between a stationary phase and a mobile phase. In paper or thin-layer chromatography, a spot of sample is placed above a solvent; as the solvent rises, components move at different rates depending on solubility in the solvent and attraction to the stationary phase.
The retention factor Rf = distance moved by the substance / distance moved by the solvent front, and is characteristic for a substance in a given solvent. Plant pigments separate into carotene (moves farthest), xanthophylls, chlorophyll a and b. Other forms are gas chromatography and HPLC.
Example: identifying amino acids by Rf values after spraying with ninhydrin.
Remember: draw the origin line in pencil so it does not dissolve.
Frequently asked questions
What is Chromatography?
Separates mixtures, such as pigments, by their different movement through a stationary phase.
Which area of biology covers Chromatography, and how advanced is it?
Chromatography is one of the 51 topics in Lab Methods & Biostatistics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Spectrophotometry, Phylogenetic Statistics, Cell Fractionation.
Can you give an example of Chromatography?
Separating chlorophyll a, b and carotenoids from leaf extract.
What should I learn before Chromatography?
Work through the Beginner topics in Lab Methods & Biostatistics first, such as Scientific Method, Hypothesis, Variables, then return to Chromatography. Intermediate topics assume the Beginner vocabulary.
What topics are related to Chromatography?
The closest topics to Chromatography are Spectrophotometry, Phylogenetic Statistics, Cell Fractionation, t-Test. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Chromatography?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Chromatography. To practise the whole of Lab Methods & Biostatistics, use the Lab Methods & Biostatistics quiz.
How is Chromatography different from Spectrophotometry?
Chromatography: Separates mixtures, such as pigments, by their different movement through a stationary phase. Spectrophotometry: Determines how much light of a given wavelength a sample absorbs, linked to concentration by the Beer-Lambert law. Read both side by side and note what each one explains.
How should I study Chromatography step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Spectrophotometry and explain the difference aloud. Finally, take the Lab Methods & Biostatistics quiz and come back to this page for any question you miss.