Sensor Eletroquímico para Determinação de Prometazina com Detecção Amperométrica de Duplo Pulso

The quantification of promethazine is of utmost importance for medical, biological and biotechnological applications.In this communication is reportedthe use of the poly(thionine) film as intrinsic sensorial material in the development of anamperometric sensor for promethazine (PMZ) detection. Cyclic voltammetrydata were interpreted to suggest that electrochemical reactions in electrode surface involve oxidation of promethazine(+0.90V / SCE) and its adsorption on the polymer film.The PMZ detection was observed with the increased of cathodic peak current (at +0.10V / SCE) of the sensor.The overall reaction scheme can be represented by an initial electrochemical step (Eq. 1) followed by a chemical step (Eq. 2)and electrocatalysisstep (Eq. 3): PMZ(red) → PMZ(ox) + e-at+0.90V(1)PMZ(ox) + poly(thionine)(red)→PMZ(ox) + poly(thionine)(ox)(2)poly(thionine)(ox)+ e-→poly(thionine)(red) at + 0.10V(3) Having CV results as a reference basis, the operating conditions for amperometric measurements were set up toPMZ detect by applying two potential levels characteristic of the detection potential corresponding to PMZ oxidation (+0.90V) and electrocatalysis (+0.10V).The chronoamperograms from double potential step experiment atpoly(thionine)/FTO electrode were recordedin 0.5 mol L-1KCl solution (pH 1.5) by successive additions of PMZ. The cathodic current of sensor was linear in the promethazine concentration range of49.8 to 385μmol L-1 with detection limit of 17.7 μmol L-1. Current(μA)=0.03+7.1×10−3[PMZ](μmolL−1)(n=7;r=0.9986;t=225s)The sensitivity determined under double pulse potential operating conditions were higher in comparison with CV.