ABSTRACT
A biomimetic potentiometric sensor for specific recognition of dextromethorphan (DXM), a drug classified according to the Drug Enforcement Administration (DEA) as a "drug of concern", is designed and characterized. A molecularly imprinted polymer (MIP), with special molecular recognition properties of DXM, was prepared by thermal polymerization in which DXM acted as template molecule, methacrylic acid (MAA) and acrylonitrile (AN) acted as functional monomers in the presence of ethylene glycol dimethacrylate (EGDMA) as crosslinker. The sensors showed a high selectivity and a sensitive response to the template in aqueous system. Electrochemical evaluation of these sensors revealed near-Nernstian response with slopes of 49.6±0.5 and 53.4±0.5 mV decade(-1) with a detection limit of 1.9×10(-6), and 1.0×10(-6) mol L(-1) DXM with MIP/MAA and MIP/AN membrane based sensors, respectively. Significantly improved accuracy, precision, response time, stability, selectivity and sensitivity were offered by these simple and cost-effective potentiometric sensors compared with other standard techniques. The method has the requisite accuracy, sensitivity and precision to assay DXM in pharmaceutical products.
Subject(s)
Antitussive Agents/urine , Biomimetics/methods , Biosensing Techniques/methods , Dextromethorphan/urine , Diethylhexyl Phthalate/chemistry , Humans , Limit of Detection , Methacrylates/chemistry , Molecular Imprinting , Pharmaceutical Preparations/chemistry , Polymers/chemistry , Polyvinyl Chloride/chemistry , Potentiometry/methods , Reproducibility of ResultsABSTRACT
The construction and electrochemical response characteristics of poly(vinyl chloride) matrix ion-selective electrodes (ISEs) for dextromethorphan (DXM) hydrobromide are described. The membranes incorporate ion-association complexes of DXM with reineckate salt {[Cr(NH3)2(SCN)4]NH4} or phosphomolybdic acid [H3(PMo12O40)], as electroactive materials and dioctylphthalate or dibutylsebacate as a plasticizing solvent mediator. The sensors display a fast, stable and linear response with slopes of 54.4 to 59.5 mV/decade at pH 2.5-6.5 and a detection limit of 1.0 x 10(-6) M. Moreover, the sensors exhibit very good selectivity for DXM over opiate alkaloids, as well as organic and inorganic cations. The sensors proved to be useful for the determination of 5.0 x 10(-5)-1.0 x 10(-3) M DXM hydrobromide in pure as well as in dosage forms by direct potentiometry and standard addition methods. Determination of 5.0 x 10(-4) M DXM using the standard addition method and a sensor based on phosphomolybdate and dioctylphthalate shows an average recovery of 99.8% and a relative standard deviation (RSD) of 0.4%.