Promethazine determination in plasma samples by using carbon paste electrode modified with molecularly imprinted polymer (MIP): Coupling of extraction, preconcentration and electrochemical determination

A promethazine (PMZ) molecularly imprinted polymer (MIP) and a non-imprinted polymer (NIP) were synthesized by two different formulations of methacrylic acid–ethylene glycol dimethacrylate (MAA–EGDMA) and vinyl benzene–divinyl benzene (VB–DVB). Then, the MIPs were used to modify the carbon paste electrode (CP). The response difference between MIP-CP and NIP-CP electrodes, containing VB–DVB polymer, was higher than that for MIP-CP and NIP-CP modified with polymer of MAA–EGDMA, indicating the lower nonselective surface adsorption property of the VB–DVB based MIP. The MIP, incorporated in the carbon paste electrode, functioned as selectively recognition element and pre-concentrator agent for PMZ determination. The prepared electrode was used for PMZ measurement by the three steps procedure including analyte extraction in the electrode, electrode washing and electrochemical measurement of PMZ. It was shown that the electrode washing, after PMZ extraction, led to enhanced selectivity. Square wave voltammetry (SWV) for PMZ determination by proposed electrode was proved to be better than that of differential pulse voltammetry. Some parameters, effective on the electrode response, were optimized and then a calibration curve was plotted. Two dynamic linear range of 7 × 10−9 to 4 × 10−7 and 4 × 10−7 to 7 × 10−6 mol L−1 were obtained. The detection limit of the method was calculated equal to 3.2 × 10−9 mol L−1. This method was used successful for PMZ determination in blood serum sample.