Molecularly imprinted polymer nano-sphere/multi-walled carbon nanotube coated glassy carbon electrode as an ultra-sensitive voltammetric sensor for picomolar level determination of RDX.

An ultrasensitive and highly selective voltammetric sensor with ultra-trace level detection limit is introduced for RDX determination in water samples. The sensing platform is the nano-sized molecularly imprinted polymer (nano-MIP)/MWCNTs nanocomposite, casted on glassy carbon electrode (GCE). The MIP was synthesized by copolymerization of methacrylic acid and ethylene glycol dimethacrylate in the presence of RDX via precipitation polymerization. The MIP was characterized by scanning electron microscopy (SEM) and fast fourier transform infrared spectroscopy (FT-IR). It was demonstrated that the MIP, coated on the electrode, have the capability to adsorb RDX and increase its related voltammetric signal. This capability was remarkably lower, for the non-imprinted polymer (NIP)-based electrode. The MIP-based electrode signal to RDX is greatly enhanced in the presence of MWCNTs. The sensor showed excellent selectivity to RDX, compared to similar compounds of HMX and TNT. It exhibited two dynamic linear ranges including 0.1-10.0 nmol L-1 and 0.01-1.00 µmol L-1. The detection limit and relative standard deviation of the sensor were calculated to be 20 pmol L-1(3Sb/m, first curve) and 4.5% (10 nmol L-1, n = 5), respectively. The utility of the sensor was checked for RDX analysis in water samples which led to satisfactory results.