Experimental Design Strategies in Lc Method Development and in Robustness Testing for Reversible Cholinesterase Inhibitor Rivastigmine in Pharmaceutical Formulation

Abstract

& An isocratic, reversed phase liquid chromatographic (RPLC) method was developed for the quantitative determination of rivastigmine hydrogen tartrate, in bulk drugs and in pharmaceutical formulation. The chromatographic separation was achieved on A Vertex Hypersil reversed phase C 18 column (25 cm  4.6 mm i.d., particle size 5 lm) using acetonitrile and phosphate buffer. The procedure was validated by linearity (correlation coefficient ¼ 0.9983), accuracy, robustness, and intermediate precision. An experimental design was used during validation to calculate method robustness and intermediate precision. For the robustness test, three factors were considered: percentage v=v of acetonitrile, flow rate, and temperature; an increase in flow rate results in decrease of the concentration of the drug from the expected value, while the percentage of organic modifier and temperature have no effect on the response. For intermediate precision measurement, the considered variables were analyst, equipment, and days. The RSD value (1.10 %, n ¼ 24) indicate a good precision.