A Specific High-Performance Thin-Layer Chromatography with Fluorescence Detection for the Determination of Some α₁-Blockers

Abstract

A specific high-performance thin-layer chromatography (HPTLC) method with fluorescence detection was developed for determination of selective α₁-blockers, including terazosin (TER), doxazosin, prazosin, and alfuzosin. So far, this is the first HPTLC method using fluorescence detection mode for the determination of α₁-blockers. It was designated to combine the specificity attributed to the drug's native fluorescence, the high sample throughputs of the HPTLC methods, and the use of environmentally safe reagents. Good resolution was obtained using simple mobile phase composed of acetonitrile and phosphate buffer (0.02 mole/L) adjusted to pH 3.0 (30:70, v/v). The method used fluorescence detection mode and was validated according to the International Conference on Harmonization guidelines. The emission intensity was measured using optical filter K400 after excitation at 332 nm. The correlation coefficient in the range 0.9984–0.9997 was obtained in the concentration range 5–100 ng/band. The limits of detection and quantification were 3.52–6.91 and 11.76–23.02 ng/band, respectively. Forced degradation stability for TER was studied using the developed HPTLC method. The proposed method was successfully applied for the determination of the studied α₁-blockers in pharmaceutical dosage forms and in human plasma without the need for complicated extraction and cleanup steps.

Keywords:

• dosage forms
• fluorescence detection
• forced degradation
• high-performance thin-layer chromatography
• human plasma
• selective α₁-blockers

Notes

^a Peak area versus concentration (ng/band).

^b Data presented as mean ± SD of three experiments.

^a Values are mean of six determinations.

^a Average of three determinations.

^b Drugs concentrations = 20 ng/band.

^c Following the optimum conditions.

^a Values are mean of five determinations.

^b Theoretical values for t- and F-tests at 95% confidence limit and n = 5 were 2.31 and 6.39, respectively.

^c BP.^[ 26-29 ^].

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