title: Non-derivatization approach to high-performance liquid chromatography-fluorescence detection for aminoglycoside antibiotics based on a ligand displacement reaction.
abstract: An indirect fluorescence detection method has been developed for detecting the aminoglycoside antibiotics following chromatographic separation. This approach to detection is based on a displacement reaction between the aminoglycosides and a copper(II)-L-tryptophan (L-Trp) complex, Cu(L-Trp)2. The aminoglycosides, which contain multiple amino groups, have strong affinities for the Cu(II) ion and displace L-Trp from the Cu(L-Trp)2 complex. The resulting increase in L-Trp fluorescence, which is quenched when coordinated to Cu(II), is indicative of the presence of the aminoglycoside. Fluorescence titration data indicate that there is a stoichiometric ratio of 1:1 between the reaction of the aminoglycosides with Cu(L-Trp)2. This HPLC detection scheme is implemented postcolumn by mixing a buffered Cu(L-Trp)2 solution with the column eluent prior to detection. The aminoglycosides were separated with the use of a column packed with a polymeric strong cation-exchanger. Separation and detection variables were optimized and are discussed. The detection limits for the aminoglycosides tested ranged from 4.2 to 14.5 ng injected (S/N=3). A linear working curve was achieved for amikacin in the range of 29-586 ng for a six point linearity test. The developed separation and detection scheme was further tested by analyzing commercial pharmaceutical formulations of these antibiotics.
authors.affiliation: Department of Chemistry, University of New Hampshire, Durham 03824, USA.
authors.forename: M
authors.initials: M
authors.lastname: Yang
authors.forename: S A
authors.initials: SA
authors.lastname: Tomellini
mesh_terms: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008024:Ligands; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D008024:Ligands