Abstract
The voltammetric behaviour of antibacterial danofloxacin (DANO) and orbifloxacin (ORBX) was studied in a wide pH range from 5 to 12 using phase sensitive alternating current, cyclic voltammetry and differential pulse cathodic adsorptive stripping voltammetric (DPCASV). The adsorption behaviour of both biological compounds at the hanging mercury drop electrode was investigated in order to achieve an increase in sensitivity and a possibility of the antibacterial DANO and ORBX determination by applying the adsorptive stripping voltammetric method. Adsorptive preconcentration followed by differential pulse cathodic stripping showed one wave at -1.27 V (DANO) and -1.37 V (ORBX) being the most sensitive for analytical determination of the investigated compounds. The limits of detection of 2.93 x 10(-9) M and 5.30 x 10(-9) M, and quantitation 9.77 x 10(-9) M and 1.77 x 10(-8) M for DANO and ORBX, respectively, were achieved. The degree of interference from coexisting metal ions and some organic compounds on the DPCASV signal for DANO and ORBX was evaluated. The proposed method was successfully applied to the determination of the studied fluoroquinolones in human urine and serum, obtained from healthy volunteers, without the necessity for sample pretreatment or time-consuming extraction steps prior to the analyses.