| This thesis is divided into five parts. It mainly researches the simultaneouse determination of pharmaceutical samples in complicated systems with the aid of chemometrics.Part oneIn this part, it is described and reviewed the application of electroanalytical chemistry in the determination of pharmaceutical analysis in the last twenty years. The potentiometry, the voltammetry and the polarography methods have been described in details. According to the features of the voltammetric method, such as selective, sensitive, rapid and inexpensive instruments, and the powerful resolution capability of chemometrics approaches.Part twoA novel voltammetric method for simultaneous determination of the glucocorticoid residues, prednisone, prednisolone and dexamethasone, was developed. These analytes gave well-defined reduction peaks in the Britton-Robinson buffer (B-R, pH 3.78) by using differential pulse stripping voltammetry (DPSV) at a hanging mercury drop electrode (HMDE). The experimental conditions were optimized at 200 mV for deposition potential, 30 s for deposition time, 50 mV for amplitude and 60 ms for pulse width. Under these selected conditions, The voltammograms were measured and sampled in the range of -750 to -1150 mV at 4 mV intervals (total 101 potential points). Due to the overlapping of their voltammograms, several chemometrics methods, partial least squares (PLS), principal component regression (PCR) were used for resolution of the measured spectra data. It was found that PLS and PCR gave good results for analysis of mixtures of these compounds. The proposed method was also applied for the determination of these glucocorticoid residues in the rabbit plasma and human urine samples with satisfactory results.Part threeAntibiotics such as oxytetracycline, tetracycline and chlortetracycline have been determined simultaneously by DPSV with multivariate calibration models. It was found that all these three compounds will be reduced at a mercury electrode in a B-R buffer (pH 3.78) and well-defined voltammetric waves can be observed. However, the voltammograms of these three compounds overlapped seriously, and thus, it was difficult to analyze these compounds individually in their mixtures. In this work, chemometrics methods were applied to resolve the overlapped voltammograms and the calibration models were established for simultaneous determination of these compounds. The proposed method was also applied for the determination of these tetracyclines (TCs) residues in fish muscle and spiked animal feeds with satisfactory results.Part fourThreeβ2-Agonists, clenbuterol hydrochloride, salbutamol and ractopamine hydrochloride have been determined simultaneously by DPSV with the aid of chemometrics. In the pH=4.56 B-R buffer, these compounds had a sensitive irreversible oxidation peak on the glassy carbon electrode. Under the optimal conditions, the peak current of was linear with its concentration in the range of 0.05～0.55, 0.05～0.45 and 0.15～1.2μg mL-1 for clenbuterol, salbutamol and ractopamine, respectively. The detection limits were 0.023, 0.0216 and 0.0383μg mL-1, relatively. The voltammetric waves of salbutamol and ractopamine overlapped seriously, we can't determine separately by changing experiment conditions. So we solved this question with the aid of chemometrics. Finally, the developed method has been applied to the analysis of real swine feed samples and has achieved satisfactory results.Part fiveA DPV method for the determination of indometacin was proposed. The electrochemical behavior and voltammetric parameters of indometacin at the gold electrode were studied and evaluated. Indometacin was hydrolyzed in the solution of NaOH with water-bath at 100℃, then a sensitive oxidative peak was observed for its hydrolyzed product, and the peak current was linear with its concentration in the range of 0.2～2.2μg mL-1 with the detection limit of 0.073μg mL-1. The proposed method was applied to the determination of indometacin in pharmaceutical preparations with satisfactory results.
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