HPLC-Fluorescent Analysis of Memantine: An Investigation on Fluorescent Derivative Formation

Abstract

Memantine is an N-methyl-D-aspartate receptor antagonist recommended for treatment of Alzheimer’s disease. Due to the lack of chromophores/fluorophores in memantine molecule, this work focuses on a novel procedure for memantine-fluorescent derivative formation enabling it to be monitored by a fluorescence detector. 4-(N-Chloroformylmethyl-N-methyl)amino-7-N,N-dimethylaminosulphonyl 2,1,3-benzoxadiazole (DBD-COCl) was chosen as a fluorescent probe since the carbonyl chloride of DBD-COCl could easily react with the amine on memantine to form the fluorescent derivative. The derivatization was achieved at 5 : 1 of DBD-COCl and memantine, at 60°C for 50 min. Structure elucidation from mass spectrometry and infrared spectroscopy spectra confirmed the amide bond of memantine-DBD-COCl. The derivative was stable up to 24 h and could be monitored by high performance liquid chromatography (HPLC) coupled with a fluorescence detector using a VertiSep GES C18 column, acetonitrile and water (80 : 20) as the mobile phase with a flow rate of 1 mL/min using the excitation and emission wavelengths at 430 and 520 nm, respectively. The derivative was eluted at 4.50 min and was separated from the DBD-COCl. Preliminary validation data reveals good linearity (r2≥0.99), repeatability (%RSD < 0.54) and accuracy (%R between 94 and 119%) with a limit of detection of 0.79 μg/mL.