A Validated Stability-Indicating RP-HPLC Method for the Simultaneous Estimation of Aloe Emodin, Aloin, and Emodin in a Marketed Formulation of Aloe Vera

The present analytical study focuses on the simultaneous estimation of Aloe emodin, aloin, and emodin as chemical markers commonly found in herbal formulations using the reversed-phase high-performance liquid chromatography (RP-HPLC) method. Aloin, Aloe emodin, and emodin are active components present in Aloe species, rhubarb, and cascara. A novel method based on RP-HPLC was developed for the simultaneous estimation of these chemical markers. A Waters Alliance-e2695 chromatograph with a 150 × 4.6 mm, 3.5 µm column, a mobile phase with acetonitrile, 0.1% formic acid, and methanol (20 : 50 : 30) were used for this analytical work. The flow rate was 1.0 mL/min, and detection was carried out by a PDA detector with an absorption wavelength of 237 nm at an ambient temperature of 25°C. The linearity ranges for Aloe emodin, aloin, and emodin were found to be 25–150, 12.5–75, and 2.5–15 µg/mL, respectively. The mean recoveries of Aloe emodin, aloin, and emodin were within the acceptance limit (98–102%). The relative standard deviation of precision and robustness was found to be less than 2%. Forced degradation studies were carried out for chemical markers with the help of the developed RP-HPLC method, and no considerable degradants were found. The developed stability-indicating method was applied for the quantification of the three markers in the Ayurvedic formulation of Aloe vera.