Application of a sensitive electrochemical sensor modified with WO3 nanoparticles for the trace determination of theophylline

An electrochemical sensor based on tungsten trioxide nanoparticles and multiwall carbon nanotubes composite was developed for the determination of theophylline (THP). WO3 nanoparticles were synthesized by the precipitation reaction in acidic media. The constructed sensor was applied for the quantification of theophylline by adsorptive stripping voltammetry. In order to achieve the best electrochemical response, the effects of different parameters such as scan rate, electrolyte solution conditions, pH and accumulation conditions were investigated. Under optimal statuses, the calibration curve represented a concentration linear range of 2.5 x 10(-8)-2.6 x 10(-6) M and a low limit of detection 8.3 x 10(-9) M. The sensor represented great selectivity for THP toward a wide diversity of foreign organic and inorganic chemicals. The modified sensor was used successfully for the measurement of theophylline in pharmaceutical and biological media.