Comment
Author: Admin | 2025-04-28
V/v/v as mobile phase and standard solutions of sildenafil and tadalafil at concentrations of 8 µg, 12 µg, 16 µg, 20 µg, and 24 µg/spot. The measurement of absorbance was performed at wavelengths of 254 nm, 289 nm, and 306 nm.Finally, a mobile phase consisting of a mixture of ethyl acetate:toluene:methanol:ammonia with a ratio of 50:30:20:0.5 v/v/v/v was selected, as the best separation of the two compounds was obtained. The concentrations of sildenafil and tadalafil for the calibration curve were 8 µg, 12 µg, 16 µg, 20 µg, and 24 µg/spot, and the measurements of absorbance were performed at wavelengths of 254 nm, 280 nm, and 306 nm. The wavelength was selected based on the maximum absorbance of the UV-VIS spectra for the compounds of interest.The specificity of the method was confirmed by comparing the Rf values and the spectra of the samples and the standard spots of sildenafil and tadalafil. The spectra showed that there were no interferences and the proposed TLC method was specific and suitable for the determination of sildenafil and tadalafil in the tested herbal supplements. Moreover, the peak purity of adulterants was assessed by comparing the respective densitograms at the peak start, peak middle, and peak end, and the average peak purity index was calculated (Table 2). The peak purity index was above 0.999 (between 0.999360 and 0.999801), suggesting that the adulterants were successfully detected under experimental conditions.The linearity of the method was evaluated by determining five levels of standard solutions of sildenafil and tadalafil in the range of 8 µg/spot to 24 µg/spot. Regression analysis of the results was used to obtain a linear regression model. The correlation coefficient (R = 0.99) indicated that the method was linear in the range of 8–24 µg/spot for both substances.The accuracy (as the percent recovery) and precision (as the coefficient of variation) were evaluated using the standard addition method at three concentration levels (80%, 100%, and 120%). For sildenafil, the accuracy ranged from 91.30% to 101.01%, while for tadalafil, it ranged from 93.45% to 100.92%. The accuracy achieved in this study outperformed a previously published HPLC method [36]. Additionally, the good performance of the method was demonstrated by the precision results ranging from 0.22% to 1.08% for sildenafil and 0.73% to 1.32% for tadalafil, all of which fell within the acceptable range of 1–5% for CV values in TLC densitometry [37]. 2.2. Analysis of Herbal Supplements 2.2.1.
Add Comment