Development of a silver functionalised polyaniline electrochemical immunosensor for polychlorinated biphenyls

An electrochemical immunosensor based on a silver nanoparticles (Ag NPs)-doped polyaniline (PANI) modified glassy carbon electrode (GCE) transducer, wherein polyclonal anti-polychlorinated biphenyl (PCB) antibody (Ab) was immobilized by a covalent linkage with glutaraldehyde (GA), was developed. The optimum conditions for the fabrication of the immunosensor were immersion, 30 min incubation in 1.0% GA. Electrochemical measurements of PCB 28 were done using the square wave voltammetry (SWV) technique. The optimum methodology conditions were a 20 mV s(-1) scan rate, sweep potential range of -1 to 1 V and PCB incubation period of 2 h. The electrochemical response obtained under these optimum conditions was linear within 0.2 and 1.2 ng mL(-1) with limit of detection (LOD) and limit of quantitation (LOQ) values of 0.063 ng mL(-1) and 0.209 ng mL(-1), respectively. The specificity of the developed sensor towards PCB 28 against benzyl chloride (BnCl) and PCB 180 was poor due to structural similarities. However, the PCB 180 results correspond to total PCB, thus indicating the sensor's applicability to regular total PCB determination. Cations and anions tested had a minimum effect on the sensor. Recoveries in water and guava juice ranged from 90% to 102%. Thus, proving the immunosensor's selectivity to PCBs and its possible application in the detection and monitoring of PCBs in food, water bodies and general environmental samples.