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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper III covers analytical and organic chemistry.

UPSC Combined Geo-Scientist, Mains · 2025 · Mains Paper III

Q2(b). Ion-exchange chromatography; retention on a strong acid resin

Question

Briefly describe the principle involved in ion-exchange chromatography. Arrange the retention time of Li⁺, Ag⁺, Zn²⁺ and Co³⁺ for a strong acid resin in an ion chromatograph. Give reasons for the sequence of retention of these species.

Answer in brief

Ions are separated by reversible, stoichiometric exchange with the counter-ions of a charged resin. Retention time: Li⁺ < Ag⁺ < Zn²⁺ < Co³⁺.

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Topic notes: chromatography and solvent extraction (plates, resolution, van Deemter, HPLC, GLC, ion exchange, Craig), with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversion-exchange chromatographyion chromatographystrong acid cation exchangerselectivity coefficientsuppressor columnhydrated radius

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