Effect of increasing concentration of ammonium acetate as an additive in supercritical fluid chromatography using CO2-methanol mobile phase

J Chromatogr A. 2009 Sep 4;1216(36):6441-50. doi: 10.1016/j.chroma.2009.07.022. Epub 2009 Jul 17.


The effects of increasing concentrations of ammonium acetate additive in supercritical fluid chromatography were studied on silica, 2-ethyl-pyridine and endcapped 2-ethyl-pyridine stationary phases. The study involved the addition of increasing concentrations of the ammonium acetate either in the mobile phase modifier (methanol) or in the sample solvent. The effects of ammonium acetate on retention and peak shape of the analytes were evaluated. Compounds that exhibited satisfactory chromatographic behaviour in the absence of the additive were virtually unaffected by its presence in the mobile phase or sample solvent. Nevertheless, compounds that exhibited late elution and strongly tailing peak shapes when pure methanol was used showed dramatically improved chromatographic behaviour in the presence of the additive. Shorter retention was observed not only when the modifier was introduced in the mobile phase but also when it was in the sample solvent.

MeSH terms

  • Acetates*
  • Anti-Inflammatory Agents, Non-Steroidal / analysis
  • Antihypertensive Agents / analysis
  • Atenolol / analysis
  • Carbon Dioxide*
  • Chromatography, High Pressure Liquid
  • Chromatography, Supercritical Fluid*
  • Diltiazem / analysis
  • Mass Spectrometry
  • Methanol*
  • Naproxen / analysis
  • Pyridines / chemistry
  • Silicon Dioxide / chemistry
  • Sulfonamides / analysis
  • Surface Properties


  • Acetates
  • Anti-Inflammatory Agents, Non-Steroidal
  • Antihypertensive Agents
  • Pyridines
  • Sulfonamides
  • 2-ethylpyridine
  • Carbon Dioxide
  • Atenolol
  • Naproxen
  • Silicon Dioxide
  • Diltiazem
  • ammonium acetate
  • Methanol