New Sensitive Spectrophotometric Methods for the Determination of Raloxifene Hydrochloride in Pharmaceuticals Using Bromate-Bromide,Methyl Orange and Indigo Carmine

Two new sensitive spectrophotometric methods are proposed for the detn. of raloxifene hydrochloride (RLX) using bromate-bromide mixt. and two dyes, methyl orange and indigocarmine, as reagents. The methods entail the addn. of a known excess of bromate-bromide mixt. to RLX in hydrochloric acid medium followed by detn. of residual bromine by reacting with a fixed amt. of either methyl orange and measuring the absorbance at 520 nm (Method A) or indigo carmine and measuring the absorbance at 610 nm (Method B). In both methods, the amt. of bromine reacted corresponds to the amt. of RLX. The absorbance is found to increase linearly with concn. of RLX. Under the optimum conditions, RLX could be assayed in the concn. range 0.1-2.0 and 0.5-6.0 μg mL-1 by method A and method B, resp. The apparent molar absorptivities are calcd. to be 1.9 × 105 and 4.5 × 104 L mol-1 cm-1 for method A and method B, resp., and the corresponding Sandell sensitivity values are 0.003 and 0.011 μg cm-2. The limits of detection and quantification are also reported for both methods. Intra-day and inter-day precision and accuracy of the developed methods were evaluated as per the current ICH guidelines. The methods were successfully applied to the assay of RLX in its tablet formulation and the results were compared with those of a ref. method by calcg. the Student's t-value and F-value. No interference was obsd. from common tablet adjuvants. The accuracy and reliability of the methods were further ascertained by recovery expts. via std.-addn. procedure. [on SciFinder(R)