title: Cation-exchange liquid chromatography of choline and acetylcholine on free shielded silanols of silica-based reversed-phase stationary phases.
abstract: Free anionic functions present on the surface of reversed-phase packing materials were used for the selective cation-exchange preconcentration and separation of the neurotransmitters choline and acetylcholine from a biological matrix. The cation-exchange behaviour of different reversed-phase packing materials in the neat aqueous mobile phase, the properties of an end-capped column, the dependence of capacity factors and peak shape on the concentration of counter ions, ionic strength, pH and the addition of acetonitrile and optimum conditions for enzymatic conversion of solutes to hydrogen peroxide were studied. The studied reversed-phase columns exhibit better pH stability and longer lifetimes than normal silica-based cation exchangers. Acetylcholine is an effective and sensitive test sample for the measurement of adsorption on silica support. A large sample volume was injected onto a precolumn inserted instead of an injection valve and after injection the solutes were focused and separated on an analytical column with a mobile phase containing tetramethylammonium perchlorate as the counter ion.
authors.affiliation: Institute of Analytical Chemistry, Brno, Czechoslovakia.
authors.forename: J
authors.initials: J
authors.lastname: Salamoun
authors.forename: P T
authors.initials: PT
authors.lastname: Nguyen
authors.forename: J
authors.initials: J
authors.lastname: Remien
mesh_terms: D000097:Acetonitriles / Q000494:pharmacology; D000109:Acetylcholine / Q000032:analysis*; D000838:Anions; D001923:Brain Chemistry; D002412:Cations; D002794:Choline / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002852:Chromatography, Ion Exchange / Q000379:methods*; D004492:Edetic Acid / Q000494:pharmacology; D004912:Erythrocytes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009206:Myocardium / Q000737:chemistry; D009994:Osmolar Concentration; D010710:Phosphates / Q000494:pharmacology; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012822:Silicon Dioxide
chemical_list: D000097:Acetonitriles; D000838:Anions; D002412:Cations; D010710:Phosphates; D000644:Quaternary Ammonium Compounds; D012822:Silicon Dioxide; D004492:Edetic Acid; C027917:tetramethylammonium; D002794:Choline; D000109:Acetylcholine; C018279:sodium phosphate; C032159:acetonitrile