Molecularly imprinted polymers for conductance sensing of Cu2+ in aqueous solutions

Metal ions are the smallest imaginable templates in molecular imprinting. Herein, we report a conductance sensor measuring the real part of impedance at 200 Hz coated with a molecularly imprinted polymer (MIP) for the selective binding Cu2+ from aqueous solutions. For that purpose N-vinyl-2-pyrrolidone – a polymerizable ligand – is pre-assembled with Cu2+ and co-polymerized with ethylene glycol dimethacrylate. The material yields rapid dynamic response toward the presence of analyte within 1 min and a lower limit of detection of 0.02 mmol L−1. When using copper chloride for imprinting, highest sensitivity can be reached: sensor effects are almost one order of magnitude higher, than for copper acetate. Furthermore, the sensor exhibits almost four-fold selectivity toward other interfering bivalent ions, such as Ni2+, Zn2+ and Co2+ and nearly seven-fold selectivity toward Na+. The sensors were successfully tested for monitoring copper in spiked real water samples.