Abstract
Ethambutol (ETB) is a first-line antitubercular drug effective against actively growing Mycobacterium tuberculosis. Resistance of the mycobacterium to ethambutol among tuberculosis (TB) patients results from inadequate or inappropriate dosing of treatment or using low quality medication. It is therefore necessary to develop reliable methods for determining ethambutol metabolic profiles of patients at point of care for proper dosing. Herein an efficient ETB sensor device is illustrated. It consists of a graphite-polyurethane composite electrode. In order to characterise the electrochemical behaviour of ethambutol at pH = 8.0 voltammetric studies were performed. The detector was assembled in a flow injection apparatus and operated at +1.2 V (vs. Ag/AgCl(NaCl sat.)). The influence of sample volume and flow rate was studied. The linear response for the method was extended up to a 1.1 mmol L−1 ethambutol solution with a detection limit of 0.0634 mmol L−1. The reproducibility of current responses for injections of 0.7 mmol L−1 ethambutol solution was evaluated to be 5.1% (n = 30) and the analytical frequency was 161 determinations h−1. Two different samples were successfully analysed and the results were in good agreement with those obtained using capillary zone electrophoresis (CZE). 
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