A ferrocene/imprinted polymer nanomaterial-modified carbon paste electrode as a new generation of gate effect-based voltammetric sensor†
Herein, a carbon paste electrode, concurrently incorporated with ferrocene and a molecularly imprinted polymer nanomaterial (Fc-MIP-CP electrode), is introduced as an innovative sensing platform for the detection of thiamine. Thiamine is an example of a weak electroactive compound that cannot be measured in trace levels by usual direct voltammetry methods. MIP nanoparticles were prepared and embedded with ferrocene together in a carbon paste electrode. The prepared electrode was used to detect thiamine via a redox probe (ferrocene) using the square wave voltammetry (SWV) technique. Utilizing the electrochemical impedance spectroscopy and cyclic voltammetry results, a new sensing mechanism was proposed based on the MIP gate effect principle. Various parameters influencing the peak signal (such as MIP and Fc percentage in the carbon paste composite, analysis pH, amplitude and frequency) were optimized. The best results were obtained in the analysis at pH = 9, a frequency of 30 Hz and an amplitude of 150 mV using 2 and 12 percent of Fc and MIP, respectively. The ferrocene signal enhancement with increasing thiamine concentration showed a linear behavior in the range of 1 × 10−6–4 × 10−9 M. The detection limit of the sensor was calculated to be 1.0 nM. The selectivity of the proposed electrode was demonstrated by using analogous molecules and other vitamin B compounds. This method was successfully applied for the determination of thiamine in serum samples and pharmaceuticals.