A VALIDATED QUANTITATIVE DETERMINATION OF ALIZARIN IN RUBIA CORDIFOLIA LINN. BY ISOCRATIC RP-HPLC

Abstract

A rapid, simple and specific reversed phase High Performance Liquid Chromatographic (RP-HPLC) method has been developed for the quantitative determination of alizarin in the methanolic extracts of roots and aerial parts of Rubia cordifolia Linn, an important medicinal plant used in Ayurveda system of medicine. Chromatographic analysis was performed by using a C₁₈ column (250 × 4.6 mm) alizarin was isocratically eluted with a solvent system composed of methanol: water (80:20, v/v), pH 3.5 adjusted with formic acid, at a flow rate of 1 mL/min, 20 µL of the sample was injected, UV detection was performed at 254 nm using a photodiode array detector and retention time was found to be 4.782 min. Parameters such as linearity, limit of quantification (LOQ) and detection (LOD), precision and accuracy are studied. The method  is linear for alizarin concentration in the range of 10-200 µg/mL with a correlation of 0.99903.The LOD and LOQ were found to be 52.54 ng/mL and 158 ng/mL respectively. The percent recoveries were found to be in the range of 98.50-102 %. Percent content of alizarin in roots and aerial parts of the plant were found to be 0.52 and 0.14 % respectively. Higher concentration of alizarin was found in roots in comparison with aerial parts. Since Rubia cordifolia Linn. is used in many ayurvedic formulations this method can be employed in quality control of the formulations containing Rubia cordifolia Linn.