Temperature- and pH-responsive aminopropyl-silica ion-exchange columns grafted with copolymers of N-isopropylacrylamide

Chikako Sakamoto, Yuji Okada, Hideko Kanazawa, Eri Ayano, Tetsuji Nishimura, Masanori Ando, Akihiko Kikuchi, Teruo Okano

Research output: Contribution to journalArticlepeer-review

71 Citations (Scopus)


We have designed copolymers of N-isopropylacrylamide, environmentally- responsive polymers, which respond to temperature and other external stimuli. In this study, we designed and synthesized copolymers that introduced ion-exchange groups. These copolymers responded to the temperature and the pH, and the copolymer-grafted aminopropyl silica beads were used as HPLC packing materials. This stationary phase altered the properties from hydrophilic to hydrophobic and from charge to non-charge by temperature and pH changes. We studied the separations of organic acids and phenylthiohydantoin-amino acids using environmentally-responsive chromatography, and confirmed the effects of the ion-exchange groups. The elution behaviors of these samples were controlled by the temperature changes without organic solvents in the mobile phase. It was confirmed that the interactions between the solute and stationary phase could be freely controlled by the temperature and the pH. Environmentally-responsive chromatography is expected to be applicable to the separation of pharmaceuticals and biomolecules, such as peptides, proteins and nucleic acids.

Original languageEnglish
Pages (from-to)247-253
Number of pages7
JournalJournal of Chromatography A
Issue number1-2
Publication statusPublished - 2004 Mar 19
Externally publishedYes


  • Amino acids
  • PTH derivatives
  • Poly(isopropylacrylamide)
  • Stationary phases LC
  • Temperature effects
  • pH effects

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry


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