Spectrofluorimetric determination of thioridazine and flupentixol in dosage forms; application to content uniformity test

Ultrasensitive determination of 10 phenothiazine derivatives and their enantiomers in biological fluids by capillary electrophoresis with contactless conductivity detection

In this study, a simple, rapid, and ultrasensitive technique was developed to identify five pairs of phenothiazine drugs by using ultrasound-enhanced and surfactant-assisted dispersive liquid-liquid microextraction (UESA-DLLME), field-amplified sample injection with capillary electrophoresis (FASI-CE), and capacitively coupled capacitively coupled contactless conductivity detection (C4D). During the CE separation process, UESA-DLLME was used for sample clean-up and offline concentration, and FASI-CE was used for the online concentration of phenothiazine enantiomers. At baseline, the five pairs of phenothiazine enantiomer drugs required 18 min for separation. UESA-DLLME was then used to extract 0.01 mM Tween 80 at pH 10 from a sample solution (extraction solvent, 100 mL of dichloromethane). Subsequently, FASI was used to stack the sample solution (buffer, 30 mM 2-(N-morpholino)ethanesulfonic acid/aspartic acid, additive 4 mM hydroxypropyl-γ-cyclodextrin, pH 2.5), and C4D was used for signal detection (amplitude, 2 Vpp; frequency, 400 kHz). The results indicated that the linear range for quantifying all analyte enantiomers was 1.0-150 nM, with a coefficient of determination exceeding 0.99. In addition, the relative standard deviations in the migration time and peak areas for the 10 analytes were less than 3.2% and 7.2%, respectively. The proposed system has a limit of detection (LOD) for the 10 analytes at a signal-to-noise ratio of 3, ranging from 0.24 to 0.28 nM. The sensitivity enhancement, which compares the LOD0 (limit of detection in the normal method) to LOD1 (limit of detection achieved using the proposed UESA-DLLME-FASI-CE-C4D method), varies between approximately 1200 and 2000 for the 10 analytes. Analysis of the 10 separated analytes spiked in urine and serum samples revealed recovery rates of 88%-106% and 89%-105%, respectively. Therefore, this highly sensitive advanced technique was successfully used to analyze phenothiazine enantiomers in urine and serum samples.

Spectrofluorimetric analysis of fingolimod via complex formation with eosin Y in its pure form, pharmaceutical preparation and biological samples

This work discuss a simple, rapid, accurate, precise, sensitive, validated and effective cost spectrofluorometric method. The technique was applied for the analysis of fingolimod hydrochloride (FIN) in pure form, capsules, human plasma and urine samples. Formation of binary complex between the suggested amino group of (FIN) with Eosin Y (EOY) is the principle of its determination. FIN was determined spectrofluorimetrically by measuring its quenching effect on the EOY native fluorescence at 575 nm after excitation at 525 nm. The fluorescence-concentration linearity was 0.1-1.0 µg mL^-1. The suggested spectrofluorimetric results have been certified according to ICH regulations and were applied for analysis of FIN in capsules, human plasma and urine samples. The validated results were accepted compared to reference method.

Use of eosin for green spectroscopic determination of mebendazole

New, sensitive, and reliable spectroscopic methods were constructed for the fast determination of the anthelmintic drug mebendazole. The methods depended on the reaction of the amino group in mebendazole with eosin in acidic medium forming an ion pair complex. The first method, Method I, relied on quenching of the native fluorescence of eosin after reaction with mebendazole at pH 3.7 using acetate buffer. Fluorescence quenching was measured at 538 nm after excitation at 518 nm. This method showed a linear response over the concentration range 5.0-20.0 μg/ml. The second method, Method II, was based on measuring the absorbance of the formed complex at 554 nm; the method showed good linearity from 7.0 to 22.0 μg/ml. Different parameters that influenced the formation of the reaction product were carefully investigated to reach the optimized conditions. A comparison between the proposed methods and a previous spectrophotometric method was carried out and there was no significant difference between them. The methods could be applied successfully to determine mebendazole in its tablet form. Moreover, the methods used water as diluting solvent, which made them compatible with the 'green' analytical chemistry principles. No organic solvents were used throughout the study.