Beginner Topic 904 of 1102 Analytical, Lab & Spectroscopy
Paper Chromatography
Separating pigments by how far they travel on paper, expressed as Rf values.
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In-depth explanation of Paper Chromatography
Paper chromatography separates the components of a mixture by letting a solvent travel up a strip of paper by capillary action, carrying each component at a rate set by its relative affinity for the stationary paper and the mobile solvent. Compounds that interact strongly with the paper move less, while compounds more soluble in the solvent move farther. Each component is characterized by its retention factor Rf, the distance moved by the spot divided by the distance moved by the solvent front, which is constant under fixed conditions. Rf values are compared against known standards to identify components. Although slow and of limited resolution, the method is simple and needs very little equipment. It has historically been used to analyse pigments and amino acids.
Going deeper: Paper Chromatography
Key ideas: Draw the baseline in pencil (ink would run), spot small, keep the solvent level below the spots, and mark the solvent front as soon as you remove the paper. Rf = distance of spot/distance of solvent front, always between 0 and 1. Run known standards alongside the unknown on the same sheet and the same solvent. Cover the tank to saturate the vapour.
Common mistakes and connections: Typical errors are measuring to the edge of the spot instead of its centre, letting the solvent front run off the paper, and using too concentrated a spot, which smears. Rf values only match when solvent and conditions are identical. Identical Rf in one solvent does not prove identity, so repeat in a second solvent. Links to TLC, polarity and partition.
Visualization of Paper Chromatography
Ink pigments travel different distances; each spot has a characteristic Rf between 0 and 1 used to identify it against standards. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Black ink separates into several coloured spots, each with a characteristic Rf value.
Frequently asked questions about Paper Chromatography
What is Paper Chromatography?
Separating pigments by how far they travel on paper, expressed as Rf values.
Is Paper Chromatography a beginner, intermediate or advanced topic?
Paper Chromatography is a beginner topic in Analytical, Lab & Spectroscopy. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Paper Chromatography?
Study these earlier topics in Analytical, Lab & Spectroscopy first: Crystallization, Recrystallization, Solvent Extraction.
What comes after Paper Chromatography?
The next topics in Analytical, Lab & Spectroscopy are Thin Layer Chromatography and Column Chromatography.
Can I practise Paper Chromatography with quizzes?
Yes. The interactive lesson includes a self-check question on Paper Chromatography, and the Analytical, Lab & Spectroscopy quiz draws on every topic in this area.
Where Paper Chromatography fits in Analytical, Lab & Spectroscopy
Paper Chromatography is topic 28 of 99 in Analytical, Lab & Spectroscopy.