Mikhail Tsvet

Portrait of Mikhail Tsvet

Whose Bands Nobody Believed · Botanist & Chemist · 1872–1919

Who poured a green leaf extract into a glass tube packed with powdered chalk, watched it separate as it ran through into distinct coloured bands, called the method chromatography, and spent the rest of his life answering the charge that his powder had destroyed the very substances he claimed to have separated.

Who was Tsvet?

Tsvet was born at Asti in Italy in 1872 to a Russian father and an Italian mother, took his doctorate at Geneva on plant cell physiology, and moved to Russia, where his Swiss degree was not recognised and he had to qualify again. He worked at Warsaw. His problem was the green colouring matter of leaves: was chlorophyll one substance or several? The methods available destroyed what they were meant to examine, because separating pigments then meant treating them chemically. Tsvet's answer, described to the Warsaw Society of Natural Scientists in 1903 and published properly in 1906, was to separate them physically and gently. He packed a narrow vertical glass tube with a powder — powdered calcium carbonate served best, though he tried many — poured a leaf extract in petroleum spirit onto the top, and washed it through with more solvent. Because the powder holds some substances more tightly than others, they travel at different speeds and draw apart into distinct zones ranged one above another down the column, which can then be pushed out and cut apart. He named it chromatography, writing in colour. What it showed was that the green of a leaf is not one substance: there are two chlorophylls, and yellow pigments besides, and they exist in the leaf rather than being made by the apparatus. That last claim was disbelieved. Richard Willstätter, the leading authority on chlorophyll, held that adsorption on the powder altered the pigments — that Tsvet was displaying artefacts. The method was set aside for thirty years, and revived only in the nineteen-thirties by Kuhn and by Karrer, and then extended in 1944 by Consden, Gordon and Martin, who ran mixtures on paper and measured how far each component travelled relative to the solvent, the ratio now called the Rf value. Tsvet saw none of this. He was displaced by the war, and died at Voronezh in 1919, aged forty-six.

Major achievements

Life in brief

Explore the life of Tsvet — five chapters

  1. Qualifying Twice — An Italian birth, a Swiss degree, and a Russian refusal
  2. A Tube Packed With Chalk — 1903, and the bands that appeared
  3. Willstätter Says the Apparatus Made Them — An objection that could not be answered
  4. Revived Thirty Years Later — Kuhn, Karrer, and a number that answered the objection
  5. The Commonest Separation in Chemistry — What a tube of chalk turned into

Read the five-chapter life of Mikhail Tsvet →

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