Antitussive drugs are one of the most extended formulations category in the world that use for supperessing cough and cold, for treating the symptoms of a cold or influenza and relief of cough(Allen and Popovich 2005)(Allen and Popovich 2005). Dextromethorphan (DXM).scheme 1.(o-3-methoxy- N-methylmorphinan) is a one of the older and popular antitussive drugs that used to treat the cold symptoms that effects centrally at the cough center to raise the threshold for coughing (Goodman 1990, Dale)(Goodman 1990, Dale)(Dale) DXM is also combined with other active ingredients like chloropheniramine and it could abuse or misuse for numbing and hallucinogenic such as LSD. (McFee, Mofenson, and ...view middle of the document...
Due to its speed, sensitivity, and selectivity of electrochemical techniques will be suitable for analyzing DXM in pharmaceutical dosage form
carbon paste electrode (CPE) is one of the simplest of all kind of electrode and offers distinct advantages, such as surface renewal in the event of surface fouling, speed and ease of preparation, rapid response the, wide linear range, and low cost, reproducible surface, the low residual current(Rubianes and Rivas 2003). CPE could modify with other material such as Carbon nanotubes (CNTs).CNTs have been one of the most material that was used for fabrication modified electrode(Gupta et al. 2011). according to unique electrochemical properties of CNTs such as electrical conductivity(Ding et al. 2005, Salimi, Miranzadeh, and Hallaj 2008), specific surface area chemical stability, high mechanical strength utilized in modified electrode. (Merkoçi 2006) other important properties related to their ability to promote electron transfer in electrochemical reactions. (Nugent et al. 2001, Vega et al. 2007)
Reagents and Solutions
All chemicals used in this study were of analytical reagent or pharmaceutical grade and were used without without further purification. Deionized water used for all sample preparation. (Ding et al. 2005)
The Britton-Robinson (BR) buffer solutions were prepared by adding 0.04 M acetic acid and 0.04 M boric acid into 0.04 M orthophosphoric acid, the pH was adjusted by the NaOH addition (0.2mM ), Stock solutions of 5mM DXM were prepared fresh daily in deionized water.
series of working standards prepared by diluting stock with BR buffer.
Apparatus and Electrodes
Cyclic voltammograms were recorded with the Autolab PGSTAT10 Electrochemical (Eco Chemie, Utrecht, The Netherlands) interfaced to a Pentium IV personal computer through a USB electrochemical .
The determination of the pH value is carried out by 827 pH meter (Metrohm Swiss made)
combined with glass electrode (Metrohm). Deionized water was prepared by an ultra-pure water system (smart 2 pure, TKA, Germany). Carbon paste electrode (CPE) as a working electrode, an Ag/AgCl electrode (Metrohm) in 3 M KCl electrolyte (Metrohm) as reference electrode and a platinum wire as auxiliary electrode (Metrohm) were applied for all the voltammetric measurements.
The body of the working electrode was a rod (2mm diameter and 5mm deep) bored at one end and filled with paste. Copper wire (rod 3-mm) is the preferred materials to be used for the external electric contact.
Preparation of Electrode
CPE/CNTs electrode were prepared using graphite powder and MWCNTs and 3.6 µl paraffin oil by hand mixing for 1 hour until to had a homogenous mixtrure and after preparation store in foil at room temperature(25o c) for every usage
paste mixture was packed into a cavity Teflon holder driven by spatula, then cleared around the porous core area and on the modified electrode. Finally the electrode was polished on the paper and glass for obtaining shiny...