| Tetracyclines and sulfonamides are widely used in the treatment of human and animal diseases.Antibiotics that are not absorbed by the body are directly discharged into the ecological environment,causing pollution and harm to soil and water.At present,the detection methods of two types of antibiotics include microbial method,spectroscopy method,immunological method,capillary electrophoresis method,chromatography method,etc.Compared with other analytical methods,electrochemical detection technology has the advantages of low cost,simple operation,short analysis time and high sensitivity,and is a very promising detection method.In this paper,tetracyclines and sulfonamides were determined by electrochemical analysis.The electrocatalytic principles of both antibiotics on different modified electrodes were studied.The main results are as follows:(1)Determination of tetracycline hydrochloride(TC)by graphene oxide nanoribbons modified electrode(GONRs/GCE)via pulse electrodeposition.The results of infrared spectroscopy,ultraviolet-visible absorption spectroscopy and Raman spectroscopy indicated that GONRs were successfully prepared in the experiment.TC undergone an irreversible oxidation reaction on GONRs/GCE,and the oxidation peak current was highest in the p H 3.0 citric acid-sodium citrate buffer solution.The peak current was proportional to the scan rate,indicating that the reaction of TC on the GONRs/GCE electrode was controlled by adsorption.Under optimized conditions,the oxidation peak current of TC showed a good linear relationship with the concentration.The linear range was 4×10-7 mol/L?1×10-4mol/L,and the detection limit was 2.0×10-7 mol/L(S/N=3).The method is simple,rapid,and can be used for TC detection in river samples.(2)Determination of chlortetracycline hydrochloride(CTC)by Ag nanoparticles modified electrode(Ag NPs/GCE)via drop-coating method.The results of X-ray diffraction and UV-vis spectroscopy indicated that Ag NPs were successfully prepared in the experiment.The optimal detection results for CTC were obtained in p H 3.3citric acid-sodium hydroxide-hydrochloric acid buffer solution.CTC undergone an irreversible electrochemical oxidation reaction of two electrons and two protons on Ag NPs/GCE,and the reaction was controlled by adsorption.Under the optimal conditions,the oxidation peak current of CTC showed a good linear relationship with the concentration.The linear range was 5×10-7 mol/L?1×10-4 mol/L,and the detection limit was 1.4×10-7 mol/L(S/N=3).The modified electrode was reproducible,stable and the detection of CTC in river samples gave satisfactory results.(3)Determination of trimethoprim(TMP)by electrochemically activated glassy carbon electrode(EGCE)via potentiostatic method.The results showed that EGCE had a higher electrochemical response of TMP than GCE.The measured oxidation peak current was highest in the p H 5.0 BR buffer solution after accumulating for 80 s at-0.2 V.TMP undergone an irreversible oxidation reaction on EGCE,and the reaction was controlled by diffusion.Under the optimal conditions,the peak current and concentration of TMP determined by differential pulse voltammetry was linearly related,and the linear range were 1.25×10-7 mol/L to 3.0×10-5 mol/L,3.0×10-5mol/L to 1.0×10-4 mol/L,respectively.The detection limit was 8.2×10-8 mol/L(S/N=3).This method is simple,fast,reproducible and stable for detection of TMP.(4)Determination of sulfamethoxazole(SMZ)by Ag nanoparticles/multi-walled carbon nanotubes modified electrode(Ag NPs/MWCNTs/GCE)via drop-coating method.The results of infrared spectroscopy,ultraviolet-visible absorption spectroscopy,Raman spectroscopy and X-ray diffraction indicated that Ag NPs/MWCNTs were successfully prepared in the experiment.The results showed that the nanocomposite modified electrode has better electrocatalytic activity for SMZ comparing with multi-walled carbon nanotubes and Ag nanoparticles modified electrodes.The measured oxidation peak current was highest in the p H 5.0 BR buffer solution.SMZ undergone an irreversible oxidation reaction of one proton and two electrons on Ag NPs/MWCNTs/GCE,and the reaction was controlled by adsorption.Under the optimized conditions,the concentration of SMZ was linear with peak current in the range of 3×10-7 mol/L to 5.0×10-5 mol/L.The detection limit was 6.4×10-8 mol/L(S/N=3).The method can be used for SMZ detection in river samples. |
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