title: Improvement of derivatized amino acid detection sensitivity in micellar electrokinetic capillary chromatography by means of acid-induced pH-mediated stacking technique.
abstract: Derivatization is a frequently used sample preparation procedure applicable to the enhancement of analyte detection sensitivity. Amino acids mostly require derivatization prior to electrophoretic or chromatographic analysis, especially if spectrophotometric detection is used. This study presents an on-line preconcentration technique for derivatized amino acids. The sensitivity of the method was improved by the utilization of the proposed acid-induced pH-mediated stacking mechanism. The method is demonstrated by preconcentration of amino acids labeled with 2,4-dinitrofluorobenzene. Use of optimized conditions for a large sample volume injection (40 s, 13.8 kPa) followed by electrokinetic injection of 0.1 M HCl (20 s, 10 kV) gave a 20- to 30-fold enhancement of sensitivity. The significance of the sweeping mechanism and pseudo-isotachophoresis for the on-line sample focusing and the influence of parameters on the preconcentration process were discussed. The applicability of the elaborated method was demonstrated using human urine samples.
authors.affiliation: Department of Pharmaceutical Chemistry, Medical University of Gdańsk, 107 Hallera Street, 80-416, Gdańsk, Poland.
authors.forename: Szymon
authors.initials: S
authors.lastname: Dziomba
authors.forename: Adrian
authors.initials: A
authors.lastname: Bekasiewicz
authors.forename: Adam
authors.initials: A
authors.lastname: Prahl
authors.forename: Tomasz
authors.initials: T
authors.lastname: Bączek
authors.forename: Piotr
authors.initials: P
authors.lastname: Kowalski
mesh_terms: D000143:Acids / Q000737:chemistry; D000328:Adult; D000596:Amino Acids / Q000302:isolation & purification* / Q000652:urine*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D004139:Dinitrofluorobenzene / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D008297:Male; D055815:Young Adult
chemical_list: D000143:Acids; D000596:Amino Acids; D004139:Dinitrofluorobenzene