Study On The Application Of Montmorillonite And Graphene Modified Electrodes In Drug Analysis

With the development of medicinal chemistry, technology of drug analysis is playing an increasingly important role, in particular, in the production, research and clinical use of medicine. Among many methods of drug analysis, the method of electrochemical analysis has much superioritiy, such as high sensitivity, wide detection range, small quantity of sample required, simple and fast operation, cheap equipment and so on. After the chemically modified electrodes (CMEs) advented, which has the advantage of improved the sensitivity and selectivity, it’s greatly expand the scope of the electrochemical application in the analysis drugs. In this work, to establish a new sensitive method of electrochemical determination, the modified electrodes by the montmorillonite and graphene were applied to the determination of some drug molecules.Part1. Study on the determination of berberine using Na-montmorillonite clay modified carbon paste electrodeThe electrochemical behavior of berberine based on the Na-montmorillonite Na-MMT clay modified carbon paste electrode (Na-MMT/CPE) was studied. The electrochemical oxidation and adsorption behavior of berberine was studied at the proposed electrode by linear sweep voltammetry (LSV) in acetate buffer (0.2mol·L-1, pH5.6). The experimental results show that there’s significant enrichment for berberine by Na-MMT. Compared with the bare CPE, a greatly improved in the detection sensitivity of berberine was abtained at Na-MMT/CPE. Optimized the pulse parameters and preconcentration parameters, a differential pulse anodic stripping voltammetric (DPASV) procedure has been developed for determination of the drug. A good linear relationship between the oxidation peak current magnitude (Ip) and the concentration of berberine was observed in the range from1.0to18.0μg·mL-1with detection limit of0.07μg mL-1(S/N=10). Nine repetitive analyses utilizing three separately fabricated electrodes were obtained and Ip remained the same with relative standard deviation (RSD) of4.2%. The proposed method was successfully applied to the determination of berberine in pharmaceutical tablets. The values of RSD and relative error (RE) by determination real sample were1.0%and-1.2%, and the value of recovery was at the range from97.9to104.4%.Part2. Study on the electrochemical behavior and determination of arotinolol hydrochloride using glassy carbon electrode, bare carbon paste electrode and Na-montmorillonite clay modified carbon paste electrodeThe electrochemical behavior of arotinolol hydrochloride at glassy carbon electrode (GCE) was studied by both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A signal anodic peak of arotinolol was observed at+1.05V in phosphate buffer solution (0.1mol·L-1, pH7.0). It’s an irreversible process controlled by diffusion with two electrons and two protons transferred. A good linear relationship between the peak current magnitude of DPV and the concentration of arotinolol was observed in the range from4.5×10-7to3.6×10-4mol·L-1with quantitation limit of3.3×10-7mol·L-1(S/N=10).The electrochemical determination of arotinolol hydrochloride at bare CPE and Na-MMT/CPE was studied again. The signal anodic peak of arotinolol was observed in the two CPE same as the GCE. The electrocatalysis and adsorption behavior of berberine was studied at Na-MMT/CPE because of the possession of MMT. Optimized the experiment parameter, the method of DPASV has been developed for determination of arotinolol. A good linear relationship between the Ip and the concentration of arotinolol was observed in the range from1.0×10-6to2.5×10-4mol·L-1with detection limit of5.9×10-7mol·L-1(S/N=10) at bare CPE. The linear relationship between the Ip and the concentration of arotinolol was observed in the range from5.0×10-8to4.5×10-4mol·L-1with detection limit of2.3×10-8mol·L-1(S/N=10) at Na-MMT/CPE.Nine repetitive analyses utilizing three separately fabricated electrodes of GCE, CPE and Na-MMT/CPE were obtained and Ip remained the same with RSD of1.8%, 3.9%and2.4%, respectively. The proposed method was successfully applied to the determination of berberine in pharmaceutical tablets.Part3. Study on the determination of ofloxacin using graphene and Nafion composite film modified glassy carbon electrodeThe electrochemical behavior of ofloxacin (OFLO) at graphene (GR) and Nafion Composite film modified GCE was studied. A significant enhanced peak current arotinolol was observed. Under the optimal experimental conditions, a good linear relationship between the peak current magnitude of DPV and the concentration of OFLO was observed in the range from1.0×10-7to1.1×10-4mol·L-1with quantitation limit of7.3×10-8mol·L-1(S/N=10). The proposed method was successfully applied to the determination of OFLO in pharmaceutical tablets. The values of RSD and RE by determination real sample were1.4%and-1.9%, and the value of recovery was at the range from99.8to101.6%.