Optimization of an Electrolyte System for the Simultaneous Separation of Nelfinavir Mesylate and Two Impurities by Micellar Electrokinetic Chromatography

A methodology for the simultaneous determination of nelfinavir mesylate and the impurities 3-hydroxy-2-methylbenzoic acid and (2R,3R)-4-((3S,4aS,8aS)-3-(tert-butylcarbamoyl)octahydroisoquinolin-2(1H)-yl)-3-hydroxy-1-(phenylthio)butan-2-aminium benzoate by micellar electrokinetic chromatography, with an analysis time of 25 min, was proposed. An electrolyte composed of sodium tetraborate buffer (pH 9.24; 25 mmol L−1), sodium dodecyl sulphate (9 mmol L−1) and methanol (10%, v/v) was optimized using a mixed-level factorial design, with

direct detection at 200 nm. After evaluating some figures of merit, such as selectivity, linearity,precision, limit of detection, limit of quantification, accuracy and robustness (using Youden’s test), the method was successfully applied to the analysis of nelfinavir mesylate and its impurities in a pharmaceutical formulation. The optimized methodology is demonstrated to be useful in the determination of these analytes in a synthesis monitoring process, in raw materials and in pharmaceutical formulations, while offering low solvent consumption, requiring a small sample and using non-specific columns as advantages.