Quantification of Sunscreen Benzophenone-4 in Hair Shampoos by Hydrophilic Interactions Thin-Layer Chromatography/Densitometry or Derivative UV Spectrophotometry

Benzophenone-4 (BZ4) was separated from surfactants, dyes, preservatives, and other components of hair shampoos by thin-layer chromatography on silica gel 60 stationary phase, with ethyl acetate-ethanol-water-pH 6 phosphate buffer (15 : 7 : 5 : 1 v/v/v/v) as mobile phase. Densitometry scanning of chromatograms was performed at 285 nm. The densitometric calibration curve for BZ4 was nonlinear (second-degree polynomial), withR>0.999. The limits of detection and quantification wereca.0.03 andca.0.1 μg spot−1, respectively. The results obtained by HPTLC-densitometry were compared to those obtained by zero and 2nd derivative UV spectrophotometry. In the case of spectrophotometric methods, calibration curves were linear withR>0.9998. The chromatographic method was fully validated.

Estimation of Tadalafil Using Derivative Spectrophotometry in Bulk Material and in Pharmaceutical Formulation

Four simple, rapid, accurate, precise, reliable, and economical UV-spectrophotometric methods have been proposed for the determination of tadalafil in bulk and in pharmaceutical formulation. “Method A” is first order derivative UV spectrophotometry using amplitude, “method B” is first order derivative UV spectrophotometry using area under curve technique, “method C” is second order derivative UV spectrophotometry using amplitude, and “method D” is second order derivative UV spectrophotometry using area under curve technique. The developed methods have shown best results in terms of linearity, accuracy, precision, and LOD and LOQ for bulk drug and marketed formulation as well. In N,N-dimethylformamide, tadalafil showed maximum absorbance at 284 nm. For “method A” amplitude was recorded at 297 nm while for “method B” area under curve was integrated in the wavelength range of 290.60–304.40 nm. For “method C” amplitude was measured at 284 nm while for “method D” area under curve was selected in the wavelength range of 280.80–286.20 nm. For methods A and B, tadalafil obeyed Lambert-Beer’s law in the range of 05–50 μg/mL while for “methods C and D”, tadalafil obeyed Lambert-Beer’s law in the range of 20–70 μg/mL, and-for “methods A, B, C, and D” the correlation coefficients were found to be > than 0.999.

APPLICATION OF UV-SPECTROPHOTOMETRY FOR DETERMINATION OF ZILEUTON IN BULK AND IN TABLETS

Zileuton is an orally active inhibitor of 5-lipoxygenase and found to inhibit leukotrienes (LTB4 , LTC4, LTD4 , and LTE4) formation and well-known for the effective treatment of asthma. Rapid, economical and simple ‘Zero order UV-spectrophotometry’ and ‘First order derivative UV-spectrophotometry’ have been developed for estimation zileuton in bulk and in-house tablets. Zileuton showed maximum absorbance at 258.4 nm in 0.01M NaOH. For Zero order UV-spectrophotometric method (Method I), two wavelengths 243.4 nm and 271.0 nm were selected for the determination of area under curve (AUC). In First order derivative UV-spectrophotometry (Method II), two wavelengths 260.0 nm and 279.60 nm were selected for determination of AUC. For both these methods, zileuton followed linearity in the concentration range of 4 - 24 µg/ mL with correlation coefficient value of 0.999. Both methods were validated as per ICH guidelines.

Spectrophotometric determination of chlorpheniramine maleate and phenylpropanolamine hydrochloride in dosage forms

A rapid and simple method for simultaneous determination of Chlorpheniramine Maleate (CPM) and Phenylpropanolamine Hydrochloride (PPM) by first derivative UV spectrophotometry has been developed in combined pharmaceutical dosage forms. The proposed method was successfully applied for the determination of drugs in physical mixture and commercial formulations and results showed good linearity, precision and reproducibility. DOI: http://dx.doi.org/10.3329/icpj.v2i5.14436 International Current Pharmaceutical Journal, April 2013, 2(5): 97-100