Carbon paste modified with Bi decorated multi-walled carbon nanotubes and CTAB as a sensitive voltammetric sensor for the detection of Caffeic acid

An environmentally friendly and uncomplicated sensor for the quantification of Caffeic acid (CA) is proposed here. Bismuth decorated multi-walled carbon nanotubes drop cast with cetyltrimethylammonium bromide demonstrates synergistic catalytic properties on enhancing the surface area of the carbon paste electrode. CA, a potent antioxidant, checks HIV reduplication and is an inhibitor of industrial corrosion. It is also noteworthy to mention that CA is one of the most investigated polyphenol compounds in its group. Several research studies have shown that a diet rich in CA reduces risk of allergic reactions and chronic diseases like asthma. It is also known to be an inhibitor of the human immunodeficiency virus type 1 (HIV-1) integrase. Consumption of food containing CA reduces the unpropitious effects of reactive species such as reactive oxygen (ROS) and nitrogen species (RNS) thus inhibiting the chain reaction from forming oxidative products. The proposed modified sensor was used to determine CA by Differential Pulse Voltammetry (DPV) technique. The influence of various factors such as pH, scan rate, and DPV parameters were studied. Optimum results were obtained at physiological pH and the response was linear over a range of 6.0 × 10 −8 to 5.0 × 10 −4  M, and a limit of detection of 0.157 nM, limit of quantification of 1.910 nM (S/N = 3). Overall reaction rate was adsorption controlled. Field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) were used to investigate the surface morphology of the sensor. The interfacial electron transfer rate was studied using Electrochemical Impedance Spectroscopy (EIS). The proposed sensor exhibited unique discerning abilities for CA amongst a host of common interferants. Detection of CA in samples such as coconut water, tea and fruit juices without subjecting it to pretreatments was successful.