title: Effect of increasing concentration of ammonium acetate as an additive in supercritical fluid chromatography using CO2-methanol mobile phase.
abstract: 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.
authors: School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK. bchacg@nus.edu.sg
authors: Amaury
authors: A
authors: Cazenave-Gassiot
authors: Robert
authors: R
authors: Boughtflower
authors: Jeffrey
authors: J
authors: Caldwell
authors: Laure
authors: L
authors: Hitzel
authors: Claire
authors: C
authors: Holyoak
authors: Stephen
authors: S
authors: Lane
authors: Paul
authors: P
authors: Oakley
authors: Frank
authors: F
authors: Pullen
authors: Stefan
authors: S
authors: Richardson
authors: G John
authors: GJ
authors: Langley
mesh_terms: D000085:Acetates; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000032:analysis; D000959:Antihypertensive Agents / Q000032:analysis; D001262:Atenolol / Q000032:analysis; D002245:Carbon Dioxide; D002851:Chromatography, High Pressure Liquid; D025924:Chromatography, Supercritical Fluid; D004110:Diltiazem / Q000032:analysis; D013058:Mass Spectrometry; D000432:Methanol; D009288:Naproxen / Q000032:analysis; D011725:Pyridines / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D013449:Sulfonamides / Q000032:analysis; D013499:Surface Properties
chemical_list: D000085:Acetates; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000959:Antihypertensive Agents; D011725:Pyridines; D013449:Sulfonamides; C051672:2-ethylpyridine; D002245:Carbon Dioxide; D001262:Atenolol; D009288:Naproxen; D012822:Silicon Dioxide; D004110:Diltiazem; C018824:ammonium acetate; D000432:Methanol