A validated spectrofluorimetric method for determination of some psychoactive drugs

A capillary zone electrophoresis (CZE) method with ultraviolet-visible detection has been established and validated for the determination of five phenothiazines: thiazinamium methylsulfate, promazine hydrochloride, chlorpromazine hydrochloride, thioridazine hydrochloride, and promethazine hydrochloride in human urine. Optimum separation was obtained on a 64.5 cm x 75 microm bubble cell capillary using a buffer containing 150 mM tris(hydroxymethyl)aminomethane and 25% acetonitrile at pH 8.2, with temperature and voltage of 25 degrees C and 20 kV, respectively. Naphazoline hydrochloride was used as an internal standard. Field-amplified sample injection (FASI) has been applied to improve the sensitivity of the detection. Considering the influence of parameters affecting the on-line preconcentration (nature of preinjection plug, sample solvent composition, injection times, and injection voltage) and due to the significant interactions among them, in this paper we propose for the first time the application of a multivariate approach to carry out the study. The optimized conditions were as follows: preinjection plug of water for 7 s at 50 mbar, electrokinetic injection for 40 s at 6.2 kV, and 32 microm of H3PO4 in the sample solvent. Also, a solid-phase extraction (SPE) procedure is developed to obtain low detection limits and an adequate selectivity for urine samples. The combination of SPE and FASI-CZE-UV allows adequate linearities and recoveries, low detection limits (from 2 to 5 ng/mL), and satisfactory precisions (3.0-7.2% for an intermediate RSD %).

Development and validation of a capillary electrophoresis method for the determination of phenothiazines in human urine in the low nanogram per milliliter concentration range using field-amplified sample injection.

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 π-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 μg ml –1 with apparent molar absorptivity in the range, 0.93 × 10 3 –1.45 × 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.

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

On-line coupling of solid-phase extraction, derivatization reaction and spectrophotometry by sequential injection analysis: Application to trifluoperazine assay in human urine

Continuous photometric method for the screening of human urines for phenothiazines

Thioridazine hydrochloride reacts with sodium nitrite and antimony(III) potassium tartrate in the presence of hydrogen peroxide to give a yellowish orange colour having maximum absorbance at 420 nm. The reaction is specific for antipsychotic phenothiazines with 1 μg/ml as visual limit of identification and provides a basis for a new Spectrophotometric determination. The colour reaction obeys Beer's Law from 0.01 to 1.25 mg/10ml thioridazine. The standard deviation does not exceed 0.050 mg/10 ml. The method is successfully applied to pure and pharmaceutical preparations of antipsychotic phenothiazines, as well as to urine samples. The quantitative assessment of tolerable amounts of other drugs is also studied.

Akbar Ali

Papers

Spectrophotometric determination of some antipsychotic phenothiazines