title: Simultaneous determination of ofloxacin and gatifloxacin on cysteic acid modified electrode in the presence of sodium dodecyl benzene sulfonate.
abstract: A novel cysteic acid modified carbon paste electrode (cysteic acid/CPE) based on electrochemical oxidation of L-cysteine was developed to simultaneously determine ofloxacin and gatifloxacin in the presence of sodium dodecyl benzene sulfonate (SDBS). Fourier transform infrared spectra (FTIR) indicated that L-cysteine was oxidated to cysteic acid. Electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV) indicated that cysteic acid was successfully modified on electrode. The large peak separation (116 mV) between ofloxacin and gatifloxacin was obtained on cysteic acid/CPE while only one oxidation peak was found on bare electrode. And the peak currents increased 5 times compared to bare electrode. Moreover, the current could be further enhanced in the presence of an anionic surfactant, sodium dodecyl benzene sulfonate. The differential pulse voltammograms (DPV) exhibited that the oxidation peak currents were linearly proportional to their concentrations in the range of 0.06-10 μM for ofloxacin and 0.02-200 μM for gatifloxacin, and the detection limits of ofloxacin and gatifloxacin were 0.02 μM and 0.01 μM (S/N=3), respectively. This proposed method was successfully applied to determine ofloxacin and gatifloxacin in pharmaceutical formulations and human serum samples.
authors.affiliation: School of Materials Science and Engineering, Shanghai University, Shanghai 200444, PR China.
authors.forename: Fenfen
authors.initials: F
authors.lastname: Zhang
authors.forename: Shuqing
authors.initials: S
authors.lastname: Gu
authors.forename: Yaping
authors.initials: Y
authors.lastname: Ding
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Xiao
authors.initials: X
authors.lastname: Liu
mesh_terms: D001557:Benzenesulfonates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003544:Cysteic Acid / Q000737:chemistry*; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D024841:Fluoroquinolones / Q000032:analysis* / Q000097:blood / Q000737:chemistry*; D000077734:Gatifloxacin; D006801:Humans; D015242:Ofloxacin / Q000032:analysis* / Q000097:blood / Q000737:chemistry*; D010084:Oxidation-Reduction; D013499:Surface Properties; D013997:Time Factors
chemical_list: D001557:Benzenesulfonates; D024841:Fluoroquinolones; C001114:dodecylbenzenesulfonic acid; D002244:Carbon; D003544:Cysteic Acid; D015242:Ofloxacin; D000077734:Gatifloxacin