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283. Voltammetric Determination of Chlorpromazine Hydrochloride & Promethazine Hydrochloride with the Use of Multivariate Calibration

Author

Ni, Yongnian, Wang, Li, Kokot, Serge, Ni, Yongnian, Wang, Li, and Kokot, Serge

Abstract

The voltammetric behavior of antipsychotic drugs, such as, chlorpromazine hydrochloride and promethazine hydrochloride has been investigated at a glassy carbon electrode in Britton–Robinson buffer of pH 9. It was found by applying the differential pulse stripping voltammetry (DPSV) that both chlorpromazine hydrochloride and promethazine hydrochloride had well formed oxidation voltammetric waves, with the peak potential for chlorpromazine hydrochloride at 620 mV, and for the two peaks of promethazine hydrochloride at 444 and 668 mV. The calibrations were linear for chlorpromazine hydrochloride and promethazine hydrochloride in the concentration ranges of 0.05–1.2 and 0.1–1 mg l−1, respectively. However, the voltammetric peaks of these two drugs, seriously overlap and it is difficult to determine them individually from a response of a drug mixture. In this work, a method for the simultaneous determination of these two drugs is proposed, and is based on their oxidation at the glassy carbon electrode. The interpretation of the complex voltammograms is achieved with the aid of chemometric methods, such as, classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS). The proposed method was applied to determine these two drugs in a set of synthetic mixtures and blood samples, and in general, satisfactory results were obtained.

Published
2001

284. Simultaneous Determination of Nitrobenzene and Nitro-Substituted Phenols by Differential Pulse Voltammetry and Chemometrics

Author

Ni, Yongnian, Wang, Li, Kokot, Serge, Ni, Yongnian, Wang, Li, and Kokot, Serge

Abstract

The voltammetric behaviour of five nitro-substituted aromatic compounds, such as nitrobenzene, 2-, 3-, 4-nitrophenol and 2,4-dinitrophenol, was investigated, and a method was developed for the simultaneous determination of these compounds, based on their reduction at a hanging mercury drop electrode (HMDE). It was found that by applying the differential pulse voltammetric (DPV) approach in a Britton–Robinson buffer of pH 5.4, nitrobenzene, 2-, 3- and 4-nitrophenol had well defined voltammetric reduction waves with peak potentials at −344, −284, −292 and −376 mV, respectively. However, 2,4-dinitrophenol had two peaks with potentials at −240 and −364 mV under the same conditions. For each compound linear calibration graphs were obtained in the general concentration range of 0.05–3.0 mg l−1. In mixtures of the five compounds, serious overlapping of voltammetric peaks was observed, and with conventional analytical methodology pre-separation steps would be required. In this study, chemometrics methods of data analysis, such as partial least squares (PLS), principal component regression (PCR) and classical least squares (CLS), were applied to resolve the overlapped voltammograms. Orthogonal experimental design was used for construction of the training sets containing the five aromatic compounds in the concentration range of 0.1–2.6 mg l−1. Five significant factors or principal components were modelled for prediction by the PLS and PCR methods, respectively. The percent of relative prediction error (RPE) was similar and acceptable for both methods being approximately ±10%. The percent of recoveries were within ±10% of the target value. The CLS method performed poorly (RPET=38%). The developed method was then applied to the analysis of these nitro-substituted aromatic compounds in field samples with similar satisfactory results.

Published
2001

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