Molecularly imprinted polymers on multi-walled carbon nanotubes as an efficient absorbent for preconcentration of morphine and its chemiluminometric determination

Abstract

A simple and selective method was described for the rapid determination of morphine based on its extraction and preconcentration by molecularly imprinted polymers (MIPs) on multi-walled carbon nanotubes (MWCNTs) prior to its chemiluminometric recognition. MIP–MWCNTs composite was obtained by copolymerization of certain monomers on the surface of vinyl modified MWCNTs using morphine as template molecule. Dispersed MIP–MWCNTs indicated good tendency and selectivity to low amounts of morphine in relatively acidic condition. Some important factors containing buffer and its pH, ionic buffer, incubation time, eluent, etc., were optimized for extraction step. KMnO₄–carbon dots (C-dots) chemiluminescence (CL) reaction was applied as recognition device for extracted morphine. Morphine can linearly quench the CL emission of this system via its interaction with C-dots. The calibration graph was obtained in the range of 0.003–1.2 mg L⁻¹ morphine concentration with a detection limit (3 s) of 0.82 μg L⁻¹. The relative standard deviation (RSD%) for five determinations of 0.01, 0.1, and 0.8 mg L⁻¹ morphine were 1.11%, 2.54% and 1.98%, respectively. The developed method has acceptable features in comparison with other reported methods and was satisfactorily applied to the accurate determination of morphine in pharmaceutical and urine samples.