| Chemically modified electrode is one of the important research analytical chemistry of today’s and sensor technology and measurement science, mainly in environmental protect, biomedical, food analysis and other fields. Nano graphene material is getting one emerging area of today’s material sciences. As graphene has the superior electrical, thermal, optical and catalytic properties, which make it had been applied in many fields. This paper had build several modified electrodes based on graphene base materials, and on this basis, we successfully studied the electrochemical behaviors and determination of the organic drugs. Also, the modified electrodes have been used to determine the real samples.This paper consists of the following parts:A graphene-modified electrode for selective determination of phenacetin was prepared. The electrochemical behaviours of phenacetin at the graphene-modified electrode was investigated by cyclic voltammetry and the results showed that the graphene film on electrode exhibited excellent electrocatalytic activity for the electrochemical redox reaction of phenacetin in 0.10 mol/L HAc-NaAc buffer solution (pH 5.0). The values of linearity range, correlation coefficient and limit of detection for phenacetin were 2.0×10-6 to 9.0×10-4 mol/L,0.992 and 8.76×10-7 mol/L respectively. The graphene-modified electrode is of excellent sensitivity and stability, and has been successfully used for determination of actual samples.Graphene based nanomaterials are in the forefront of chemical research. We first reported that the grapheme/Nafion modified glassy carbon electrode which the graphene was dispersed by Nafion and ethanol. The electrochemical behaviours of ligustrazine hydrochloride (LZC) at the graphene-modified electrode was investigated by cyclic voltammetry and the results showed that the graphene film on electrode exhibited excellent electrocatalytic activity for the electrochemical reduction of ligustrazine hydrochloride in HCl-KCl (pH 2.0). The reduction peak potential of Ligustrazine Hydrochloride shifted positively from-0.70 V with a bare GCE to-0.602 V (vs.AgCl/Ag) with the GCE/Nafion-Graphene, with the peak potential shifted positively around 100 mV and the peak current increased obviously. The values of linearity range, correlation coefficient and limit of detection for Ligustrazine Hydrochloride were 1.0×10-7 to 2.0×10-4 mol/L,0.995 and 6.82×10-8 mol/L respectively. The graphene-modified electrode is of excellent sensitivity, selectivity and stability, and has been successfully used for determination of ligustrazine hydrochloride in LZC injection.An electrochemical sensor, based on a graphene-Nafion composite film modified glassy carbon electrode (GCE), was developed and used for detection of trace amounts of Chloromycetin. Owing to the large surface area, good conductivity of graphene and good affinity of Nafion, the sensor exhibited excellent electrocatalytic activity for the reduction of Chloromycetin, displaying a wide linear response from 5.0×10-7 to 8.0×10-4 mol/L and a low detection limit of 3.7×10-7mol/L in 0.1 mol/L NH3-NH4Cl solution(pH 9.4). The method was also applied successfully to detect Chloromycetin in medicinal tablets.A new graphene oxide modified glassy carbon electrode (GO/GCE) was prepared for electrochemical detection of nimesulide by the cyclic voltammetry. The analytical conditions, such as pH, amount of GO suspension, and accumulation time, have been optimized. The results show that in 0.25 mol/L phosphate buffered solution (PBS) at pH 6.6, the graphene oxide modified electrodes have a significant electrocatalytic effect on nimesulide. The reduction peak potential of nimesulide shifted positively from-0.70V with a bare GCE to-0.568V with the GO/GCE, and the sensitivity increased 7 times. The peak current and nimesulide concentration show up a linear relationship over the range of 4.86×10-7 to 9.72×10-5 mol/L (R=0.999) with a detection limit of 3.24×10-7 mol/L. Thus, this modified electrode has good selectivity, high stability and reproducibility, and is suitable for determinating the drug content in tablet samples.A new method for the detection of nifedipine(NIF) was founded based on the Nafion-graphene modified glassy carbon electrode. In the papers, In 0.1 mol/L NH4Cl-NH3(pH 9.0) buffer solution, the graphene modified electrodes exhibited a remarkable catalytic and enhancement effect on reduction of the NIF. The reduction peak potential of NIF shifted positively from-1.037V with a bare GCE to-0.937V with the modified electrode, and the sensitivity increased 15 times. Some experimental conditions were optimized. The linear range between the peak current and the concentration of NIF was 4.0×10’6～1.0×10-4 mol/L(R=0.9912) with a detection limit of 4.0×10’6 mol/L by using different pulse voltammetry. The electrochemical behaviors of NIF were studied, and the electrode process was irreversible with adsorptive characteristics. Electron transfer coefficient(a=0.47), proton number (X=1) and electron transfer number (n=3) have been determined. The method has been used to determine the content of NIF in medical tablets.Determination and electrochemical behavior of chlorpromazine hydrochloride(CPZ) were studied firstly on a graphene modified electrode in 0.12 mol/L PBS (pH 6.9) solution. A sensitive pair of redox peaks of CPZ was obtained by cyclic voltammetry, the oxidation peak potential shifted negatively from 0.6323 V at bare GCE to 0.5618 V at modified electrode, and the sensitivity increased ca.4 times. On the optimized conditions, the linear range between the peak current and the concentration of the CPZ was 4×10-8-4×10-5 mol/L (R2=0.9923) with a limit of 2.0×10-8 mol/L. The electrode oxidation process of the CPZ at graphene modified electrode was confirmed to be irreversible with adsorptive characteristics. This method has been used to determine the content of CPZ in medical tablets.The recovery was determined to be 95～110% by means of standard addition method. |
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