Detection of theophylline utilising portable electrochemical sensors

Abstract

The electrochemical oxidation of theophylline (TP) is investigated utilising screen-printed electrodes. Through thorough investigation of pH, we propose a reaction mechanism, finding that the oxidation of TP is stable over a wide pH range, in particular under acidic conditions. Conversely under alkaline conditions, theophylline fouls the electrode surface. The screen-printed carbon sensors are applied towards the electroanalytical sensing of TP with a remarkable amount of success in aqueous solution at physiological pH. The screen-printed sensors have been shown to be applicable to the detection of TP at unharmful, medicinally relevant (55–110 μM), and toxic concentrations in aqueous media at physiological pH. Thus this work presents a proof-of-concept approach towards TP detection utilising sensors commonly implemented in point-of-care applications.