Determination of chlorpromazine, levomepromazine, and promethazine by sequential injection analysis with VIS spectrometric or spectrofluorimetric detection
Abstract
Automatic sequential injection analysis (SIA) with spectrometric or spectrofluorimetric detection is presented for the determination of three selected phenothiazines (chlorpromazine, levomepromazine, and promethazine) in pharmaceutical formulations. The determination is based on the oxidation of phenothiazine by cerium(IV) in acidic media, which leads to the formation of a color product that is detected by either VIS spectrometry or spectrofluorimetry.
The conditions of SIA were optimized and second-order polynomial calibration equations were established in a dynamic range of 3-350 mg dm(-3) for VIS detection, 0.05-50 mg dm(-3) for spectrofluorimetric detection, respectively. The limit of quantitation was established 0.31 mg dm(-3) for VIS detection, 2.6 x 10(-3) mg dm(-3) for spectrofluorimetric detection, respectively.
The sample throughput was 24 h(-1) for VIS spectrometric, 20 h(-1) for spectrofluorimetric, respectively, detection. Common excipients of the dosage forms (fructose, glucose, lactose) did not affect the measurement even at concentrations 200 times higher than phenothiazine.
The method was used for the phenothiazine assay in authentic samples of commercial pharmaceutical formulations, and the results were in good agreement with the official pharmacopoeial method. The advantages of the developed SIA method are its complete automation, speed, very low reagent consumption, and a wide dynamic range of analyte concentrations, enabling it to be advantageously used for routine product control in the pharmaceutical industry.