HPLC/Elsd Determination and Validation of Alpha Lipoic Acid and Sucralose in Bulk and in Their Pharmaceutical Dosage Forms

Abstract

Accurate, sensitive, robust, and direct isocratic reversed phase-HPLC methods, using Evaporative Light Scattering Detector (ELSD), had been developed and fully validated for the detection and quantification of two non-chromophoric nutraceuticals; alpha-lipoic acid (ALA) and Sucralose (SUC). Chromatographic separation was achieved using C18 Zoprax, five μm, 15 cm column for both compounds. For ALA, the mobile phase was composed of acetonitrile: 0.1 M acetic acid (60:40, v/v), adjusted at pH 2.5 with 0.6 mL/min flow rate. For SUC, acetonitrile: deionized water (70:30, v/v) with a 1 mL/min flow rate was used. Temperatures of the drift tube, column, and spray chamber have been set to be 40°C and 30°C respectively during both assays. All varying chromatographic parameters were studied carefully. ALA and SUC had eluted at 4.81±0.02 min and 1.70±0.01 min, respectively. The obtained exponential ELSD responses for the two developed methods were linearly modeled using logarithmic transformation. For ALA and SUC estimation, good linearities were achieved over the concentration ranges of 100-750 ppm and 16-500 ppm. The suggested methods disclosed excellent precision and accuracy levels. All validation parameters were fulfilled according to the United States Pharmacopeia (USP) elements and International Council for Harmonisation (ICH) guidelines. Satisfactory percentages of recovery (>97%) resulted upon methods application for the assay of each dietary supplement in its pharmaceutical formulation. A comparative statistical study was conducted between the proposed HPLC/ELSD methods and the reported HPLC/UV method for ALA and the reported HPTLC method for SUC. Student's t-tests and F-variance ratios for both methods had resulted in satisfactory values.