[Preparation and characterization of parathion sensor based on molecularly imprinted polymer]

A novel electrochemical sensor for the detection of parathion based on molecularly imprinted polymer of self-assembled o-aminothiophenol onto gold electrode was constructed. The polymerization solution was prepared from a 10 mmol/L parathion, 5 mmol/L tetra-n-butylammonium perchlorate, 30 mmol/L o-aminothiophenol solution of dichloromethane. Electropolymerization was carried out over 30 cycles between -0.3 V and 1.4 V. The template molecules were removed from the modified electrode surface by washing with 0.5 mol/L hydrochloric acid. Cyclic voltammetry was employed in the process of electrochemical measurements. The experimental results show that the optimum acidity of background solution is pH 6.8 and the optimum incubation time is 10 min. A highly linear response to parathion in the concentration range of 1.0 x 10(-4)--5.0 x 10(-7) mol/L is observed, with a detection limit of 2.0 x 10(-7) mol/L estimated at a signal-to-noise ratio of 3. The sensor has been applied to the analysis of parathion in real sample with recovery rates ranging from 98.0% to 104%. Parathion imprinted and nonimprinted polymer films were exposed to a series of closely related compounds, e.g. methyl-parathion, paraoxon, phoxim, omethoate, nitrobenzene and o-, m-, p- nitrophenol, and the sensor exhibited good selectivity and sensitivity to parathion.