Application Of Voltammetry Combined With Chemometrics In The Quantitative Determination For Some Pharmaceutical Samples

The pharmaceutical analysis chemistry is a subject of research the analytic procedure of pharmacal chemical composition and the related theoretics. It's an important branch of analytical chemistry. Its main features are the complexity of medium and the microdose of sample quantity. The application of chemometrics in pharmaceutical analysis has been developed. The combination of electroanalytical chemistry with chemometrics techniques can be used to solve some problems, which are countered in spectrum resolution.The paper is divided into five parts.In Chapter one, a review on research the application of electroanalytical chemistry in the determination of pharmaceutical samples was arised. One of the current requirements in pharmaceutical analysis chemistry is to detect and quantify smaller amounts of medicine in tables or body fluid with low cost and time consumption. Hence, selective, sensitive, rapid and inexpensive methods of analysis, using rapidly available and conventional instrumentation must be developed. In part one, it is described and reviewed the application of electroanalytical chemistry in the determination of pharmaceutical analysis. The potentiometry, the voltammetry, the polarography and the chemically modified electrodes methods have been described in details, and the application of chemometrics has also been discussed.In Chapter two, the electrochemical behavior and the simultaneous determination method of Ascorbic acid, Rutin and Quercetin in the food and health products on the glassy carbon electrode were investigated by differential pulse voltammetry with the aid of chemometrics. Moreover, we discussed the mechanism of the potential determining reaction. In the pH=5.2 KH₂PO₄-Na₂HPO₄ buffer solution, both Rutin and Quercetin had a pair of sensitive reversible oxidation-reduction peak, but Ascorbic acid only had an irreversible oxidation peak on the glassy carbon electrode. In the range of 0.35-0.50V, the three components existed serious overlap. Furthermore, there was a great discrepancy between the actual measurements and the theoretical values of the three components mixture, which would show that there was strong interaction among the three components, so it was extremely difficult to realize direct measurement for the content of single component. This paper inducted chemometrics to determine the admixture of the three components. In this way, we could avoid the troublesome procedures of separation and purification, and we could assay the artificial compound of the three components all at once. We estimated the three components in the food and the health products with satisfactory results.In chapter three, the electrochemical behavior of Hydrochlorothiazide, Pyridoxine and Promethazine in the compound hypotensors named Fufangluobuma tables and Fufanglixueping tables on the ethylenediamine modified glassy carbon electrode were investigated by differential pulse voltammetry. Moreover, we discussed the mechanism of the electrode modification and the potential determining reaction. In the Britton-Robinson buffer solution, we adjusted pH to 3.4, both Hydrochlorothiazide and Pyridoxine had a sensitive irreversible oxidation peak on the ethylenediamine modified glassy carbon electrode. The peak potentials of the two medicines ranged from 1.10V to 1.20V. But under this degree of acidity, there wasn't any peak of Promethazine in the range of potentials. In this way, we could avoid the disturbance of Promethazine. Under the optimal condition, the peak current of Hydrochlorothiazide was linear with its concentration in the range of 0.10～1.00μg/mL, and the concentration range of Pyridoxine was 0.02～0.20μg/mL. The detection limits were 37.6 and 7.00 ng/mL relatively. The paper inducted chemometrics to assay the admixture of the two medicines. In this way, we could determine the two components in the compound hypotensors simultaneously with satisfactory results.In chapter four, the electrochemical behavior and the contemporary determination method in the metabolic blood of two kinds of nucleoside analogues as antivirus named Aciclovir and Penciclovir, on the ethylenediamine modified glassy carbon electrode were investigated by differential pulse voltammetry. In the pH=2.56 Britton-Robinson buffer solution, both Aciclovir and Penciclovir had a sensitive irreversible oxidation peak on the ethylenediamine modified glassy carbon electrode. The peak potentials of the two medicines were 1.198V and 1.170Vrespectively. Under the optimal condition, the peak current of Aciclovir was linear with its concentration in the range of 0.20～4.00μg/mL, and the concentration range of Penciclovir was 0.02～0.40μg/mL. The detection limits were 77.3and 12.2ng/mL relatively. The paper inducted chemometrics to determine the admixture of the two medicines. We estimated the two kinds of nucleoside analogues as antivirus in the metabolic blood of Balb/c mouse with satisfactory results.In Chapter five, a differential pulse stripping voltammetry method for the determination of Ursolic acid in Chinese traditional medicines was developed. The electrochemical behavior and voltammetric parameters of Ursolic acid at a glass carbon electrode were investigated and evaluated. In the pH=5.3 NaAc-HAc buffer solution, Ursolic acid has a sensitive irreversible reductive peak. Under the optimal condition the peak current was linear with its concentration in the range of 0.5～9.0pg/mL. The detection limit was 0.17pg/mL. It was applied to the determination of Ursolic acid in three Chinese traditional medicines with satisfactory results.