Nanogram/mL detection of nortriptyline: Preparation of a molecularly imprinted polymer for spectrophotometric...

In this work, the molecularly imprinted polymer was used as a selective sorbent in solid-phase extraction method for the spectrophotometric determination of nortriptyline at 239 nm. Molecularly imprinted polymer was synthesized by pyrrole as a functional monomer in the presence of nortriptyline as a template. Several factors, consist of the concentration of the monomer to template ratio, amount of initiator, stirring rate, reaction time, the pH of the buffer solution, amount of sorbent, loading time, shaking rate of loading, extraction time, and shaking rate of extraction were evaluated due to their effectiveness in the preparation and extraction capability of molecularly imprinted polymer. Multivariate optimization methods, such as Plackett-Burman and central composite designs, were employed to find and optimize the significant factors. Under the selected optimal conditions, molecularly imprinted polymer showed a linear range from 0.1 to 100 µmol/L (0.026 to 26 µg/mL) nortriptyline, a detection limit of 10.3 nmol/L (2.7 ng/mL), a highly repeatable (relative standard deviation of 3.7%) and reproducible response (relative standard deviation of 4.6%), and a good selectivity in the presence of structurally related molecules. Furthermore, molecularly imprinted polymer showed high extraction efficiency and was successfully used for the determination of nortriptyline in real samples.