Simultaneous Voltammetric Determination of Theophylline and Guaifenesin Using a Multiwalled Carbon Nanotube-Ionic Liquid Modified Glassy Carbon Electrode

A glassy carbon electrode (GCE) modified with multiwalled carbon nanotubes (MWCNTs) and a hydrophobic ionic liquid (IL), was used for the simultaneous voltammetric determination of theophylline (TP) and guaifenesin (GF). The results showed that the oxidations of TP and GF were facilitated at modified electrode and peak-to-peak separation at MWCNT-IL/GCE (252 mV) was larger than that observed at unmodified GCE (165 mV). Voltammetric signals for TP and GF exhibited linear ranges of 0.5 to 98.0 mu M (R-2 > 0.99) and 1.5 to 480.0 mu M (R-2 > 0.99), respectively. The method was used to estimate TP and GF contents in some real samples.