Research And Application On The Electrochemical Detection Methods Of Chloramphenicol And Ampicillin Sodium

In this paper, three kinds of electrochemical detection methods of chloramphenicol and ampicillin sodium were developed and successfully used in the food samples. The main contents were as follows:(1) Polydopamine(PDA) film was modified on the surface of glassy carbon electrode(GCE) by the self-polymeric reaction of dopamine(DA), then overoxidized polydopamine film modified electrode(OPDA/GCE) was obtained by overoxidized treatment.Furthermore, Square wave voltammetry(SWV) was used to detect chloramphenicol(CAP)residues of milk and honey samples. Electrochemical test methods for the CAP, the influence and removal methods of dissolved oxygen, self-polymerization time of DA were investigated and optimized. OPDA/GCE, which was obtained by dipping GCE in 2 mg/m L DA solution for 2.5 h and overoxidized treatment in 0.5 mol/L Na OH solution, had good electrochemical response on CAP by the cathode scanning of SWV. The peak current and concentrations of CAP showed a good linear relationship in the range of 3.0×10-6~1.1×10-3mol/L, and the detection limit was 7.8×10-7 mol/L. The preparation method of the modified electrode is simple, inexpensive and convenient for batch perparation. The detection method of CAP is simple, high-selective and can be used for the determination of CAP residues in milk and honey.(2) CAP was used as the template molecule and o-phenylenediamine(o-PD) as functional monomer, the electrochemical biomimetic sensor was developed via electropolymerizing o-PD on the surface of a platinum microelectrode(Pt ME) for fast and selective detection of CAP in honey and milk samples. The response of the imprinted sensor had a linear relationship with concentration of CAP in the range of 9.0×10-10~1.0×10-8 mol/L.The detection limit was 3.9×10-10 mol/L based on the signal to noise ratio of 3. The sensor was applied to determine CAP in honey and milk, and the results were in good agreement with those obtained by HPLC-MS. The fabrication of the sensor was simple. Together withgood selectivity and high sensitivity of the CAP-MIP/Pt ME, the proposed sensor had useful in field test and analysis.(3) In order to establish a rapid detection technique of ampicillin sodium, it was used as template molecule, o-PD as functional monomer, PPD film was electropolymerized on the surface of a gold electrode by using cyclic voltammetry(CV). And the ampicillin sodium molecularly imprinted sensor was obtained by eluting template molecule. The electrochemical properties of the sensor were investigated using CV and SWV methods. The response current of the sensor had good linear relationship with the concentration of ampicillin sodium in a range of 1.0×10-6~9.0×10-6 mol/L. The detection limit was 6.4×10-7mol/L. The proposed method was applied to determine ampicillin sodium in milk. The results showed that the detection technique was rapid, inexpensive, and suitable for determination of ampicillin sodium in milk and other food samples.