Development and validation of a HPLC method for the determination of sertraline and three non-chiral related impurities

In this study, a screening on reversed-phase stationary phases (including C8, C18, CN, PEG and amide) was carried out in order to obtain an efficient HPLC method for the determination of sertraline and three of its more closely related synthetical and non-chiral impurities, without using ion-pair reagents. The best results in terms of both retention time and resolution of the target analytes were obtained with a Zorbax Bonus-RP column, which contains a polar amide group embedded in a C14 alkyl chain.Once the most suitable stationary phase was chosen, the HPLC method was optimized by using a factorial design, evaluating three quantitative factors (column temperature, buffer pH and buffer concentration) in order to find the best conditions which maximize the resolution between impurities A and B (positional isomers) and minimize the total run time. The final HPLC conditions were set by means of a second experimental design, which allowed optimizing the effects of the buffer pH and the proportion of methanol in the mobile phase.The optimal conditions for simultaneously determining sertraline and its impurities, being baseline separated in less than 10 min, were finally obtained with Zorbax Bonus-RP column (150 mm × 4.6 mm, 5 μm), under isocratic conditions with phosphate buffer (pH 2.8; 10 mM)–methanol (63:37, v/v) at 50 °C, at the flow-rate of 1.0 mL/min. UV detection was set at 220 nm.This method was successfully validated following ICH guidelines and it proved to be reliable for the determination of sertraline and related impurities in tablets as pharmaceutical forms.