The Preparation And Application Of Voltammetric Sensor Of Nitrogen Heterocyclic Antibiotics

The voltmmetric characteristics of ciprofloxacin,metronidazole and piperacillin sodium on the carbon paste voltammetric sensor were studied, and the new analiytical method determinated the antibiotics were proposed.1. The carbon paste voltammetric sensor for ciprofloxacin with 64.5% carbon powder and 35.5% liquid paraffin was prepared. In a pH 9.0 NH3·H2O-NH4Cl buffer solution, on the sensor the ciprofloxacin showed a sensitive cathodic stripping voltammetric wave at ^-1.38V, which can used to determine the trace ciprofloxacin. Over the range from 7.0×10-8 mol·L^-1～9.7×10-7 mol·L^-1, the linear equation of the peak current to the drug concentration is y=5.77+1.42 x, with the interrelated coefficient of 0.998 and from 2.0×10^-6 mol·L^-1～1.3×10^-5 mol·L^-1 the linear equation is y=14.4+1.75 x, y,μA·s^-1/2, x, mol·L^-1, with the interrelated coefficient of 0.997. The limit of detection is 5.7×10^-8 mol·L^-1. The liquid-exchange experiment showed the ciprofloxacin has absorbability on the sensor. The cyclic voltammetry indicated that the ciprofloxacin was adsorbed on the sensor and then carried out reversible electrochemical reaction with the transferred electron number of 2. 2. The carbon paste voltammetric sensor for metronidazole with 69.0% carbon powder and 31.0% soyabean oil was prepared. In a pH 5.8 HOAc-NaOAc buffer solution, on the sensor the metronidazole showed a sensitive cathodic stripping voltmmetric wave at -0.90V, which can used to determine the trace metronidazole. Over the range from 3.0×10^-7 mol·L^-1～1.0×10^-5 mol·L^-1, the linear equation of the peak current to the drug concentration is y=2.91+2.52 x, y,μA·s^-1/2, x,mol·L^-1, with the interrelated coefficient of 0.999. The limit of detection is 2.4×10^-7 mol·L^-1. The cyclic voltammetry indicated that the metronidazole was adsorbed on the sensor and then carried out reversible electrochemical reaction with the transferred electron number of 2.3. The carbon paste voltammetric sensor for piperacillin sodium with 63.5% carbon powder and 36.5% liquid paraffin was prepared. In a pH 3.5 B-R buffer solution, on the sensor the piperacillin sodium showed a sensitive cathodic stripping voltmmetric wave was at ^-1.58V, which can used to determine the trace piperacillin sodium. Over the range from 3.0×10-7 mol·L^-1～9.8×10-7 mol·L^-1, the linear equation of the peak current to the drug concentration is y=1.15+3.15 x, with the interrelated coefficient of 0.999; and from 1.0×10^-6 mol·L^-1～1.2×10^-5 mol·L^-1, the linear equation is y=28.7+3.30 x, y,μA·s^-1/2, x,mol·L^-1,with the interrelated coefficient of 0.998. The limit of detection is 2.3×10-7 mol·L^-1. The liquid-exchange experiment showed the ciprofloxacin has absorbability on the sensor. The cyclic voltammetry indicated that the ciprofloxacin was adsorbed on the sensor and then carried out reversible electrochemical reaction.These proposed methods were directly used to determine the trace drug in blood serum.