Determination of Some Phenothiazine Drugs Based on Colour Reaction with Potassium Periodate

Simultaneous determination of three banned psychiatric drugs in pig feed and tissue using solid-phase reactor on-line oxidizing and HPLC-fluorescence detection

The banned addition of psychiatric drugs such as phenothiazines to animal feed and foodstuffs increases the risk of human organ lesion. Phenothiazines usually exhibit weak native fluorescence and can be oxidized to strongly fluorescent compounds. In this study, a novel, sensitive and convenient method of HPLC-fluorescence detection based on post-column on-line oxidizing with lead dioxide solid-phase reactor has been developed for simultaneous determination of three banned psychotropic drugs, promethazine, chlorpromazine and thioridazine. Three compounds were successfully separated on an Agilent TC-C18 column with mobile phase of acetonitrile (A) and water (B), both containing 0.5% (v/v) formic acid. A gradient elution was programmed and fluorimetric detection was performed at λex /λem of 332/373 nm for promethazine, 340/380 nm for chlorpromazine and 352/432 nm for thioridazine. The calibration graphs gave good linearity over the concentration ranges of 30.0-4976.4 µg/L for promethazine, 2.0-2153.2 µg/L for chlorpromazine, and 15.0-3088.0 µg/L for thioridazine, and correlation coefficients (r) were ≥0.995. The method was applied to the determination of phenothiazines in pig feed and pig tissue, and the average spiked recoveries were in the range 69.1-115.4%.

Spectroelectrochemical determination of chlorpromazine hydrochloride by flow-injection analysis

An original, simple and sensitive flow-injection spectroelectroanalytical method for the determination of chlorpromazine in pure form or in pharmaceutical formulations is described. The method is based on the formation of a stable cationic radical by electro-oxidation in sulfuric acid medium (0.1 mol l(-1)), monitored in situ at lambda=524 nm. The determination of chlorpromazine hydrochloride in pure form or in pharmaceutical formulations was explored, considering the amperometric and the absorptiometric signal. The association of these two signals enhanced the selectivity of the analysis and proved decisive when other electroactive compounds or excipients like ascorbic acid were present in the formulation. The analytical parameters have been evaluated and the results obtained using standard additions are in agreement with the reference methods.

Bead injection spectroscopy-flow injection analysis (BIS-FIA): an interesting tool applicable to pharmaceutical analysis

A bead injection spectroscopy-flow injection analysis (BIS-FIA) system for the spectrophotometric detection of promethazine and trifluoperazine is developed. The sensor is based in the oxidation of the phenothiazines by Fe(III) which is later determined by formation of the complex between Fe(II) and Ferrozine, [FeFz(3)](4-). Immediately, this complex is retained on a homogeneous bead suspension of Sephadex QAE A-25 resin (500 microl) which has been injected previously in the system to fill a commercial flow-cell (Hellma 138-OS). The use of BI with respect to the use of a reusable flow-through sensor is justified because the complex is so strongly retained on the beads that the regeneration of the solid support becomes extraordinarily difficult in the proposed method. At the end of the analysis, beads are automatically discarded from the flow-cell, by reversing the flow, and transported out of the system. The analytical signals are measured at a wavelength of 567 nm, corresponding to the absorbance of the complex. Using a sample volume of 600 microl, the analytical signal showed a very good linearity in the range 0.5-8.0 microgml(-1) and 0.5-10.0 microgml(-1), with detection limits of 0.09 and 0.14 microgml(-1) for promethazine and trifluoperazine, respectively. R.S.D.s (%) lower than 2% were obtained for both analytes. The proposed method is highly selective in the presence of other species that are normally encountered with these analytes. The sensor was satisfactorily applied to pharmaceutical preparations.

Determination of some psychotropic phenothiazine drugs by charge-transfer complexation reaction with chloranilic acid

A spectrophotometric method is described for the determination of four commonly used psychotropic phenothiazine drugs. The method is based on the measurement of the intensely coloured charge-transfer complex formed by the interaction of these drugs as n-electron donors with chloranilic acid as the pi-acceptor. The coloured species measured exhibits maximum absorption at 535 nm. The molar-combining ratio and optimum assay conditions are reported. Beer's law is obeyed over the range, 25-250 microg ml(-1) with apparent molar absorptivity in the range, 0.93 x 10(3)-1.45 x 10(3) l mol(-1) cm(-1). The limits of detection and quantification are reported. The proposed method was applied to the determination of these psychotropics in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise and reproducible as the official methods. The validity of method was established by recovery studies via standard-addition technique with satisfactory results.

Separation of N-alkyl phenothiazine sulfones by HPTLC using an optimum mobile phase

In high performance thin layer chromatography some form of optimization is necessary if complete separation of all components is required. The selection of mobile phase composition is one of the most important components of an optimization strategies. The aim of this paper is the separation of the N-alkyl phenothiazine sulfones by high performance thin layer chromatography using an optimum mobile phase system. The optimum composition of mobile phase (toluene-ethyl ether-chloroform, 30:50:20, v/v) are given by the maximum of objective function (F(obj)=10.6110).

Kinetics and Mechanisms of the Non-Catalyzed and Manganese(II) Catalyzed Oxidation of Neutral Red with Potassium Periodate in Aqueous Solution

A detailed kinetic and spectrophotometric investigation has been made for the oxidation of neutral red, a cationic phenazine dye, using potassium periodate in aqueous media. The rate of the oxidation reaction attained a first order dependence on the dye and the oxidant only at lower concentrations of the latter. The rate of reaction increases with increasing pH of the medium due to the deprotonation of the substrate nitrogen atoms. Moreover, the rate of reaction decreases with increasing ionic strength of the medium, suggesting an interaction between two singly oppositely charged ions in the activated complex. However, addition of trace amounts of manganese(II) ions sharply increases the oxidation rate. Mechanisms are proposed for both the non-catalyzed and manganese(II) catalyzed reactions which are in agreement with the experimental data.