A polypyrrole-chitosan/nickel ferrite nanoparticle composite layer was prepared using the electrochemical method to detect nickel, iron, cobalt, aluminium, manganese, mercury, and lead ions. The polypyrrole-chitosan/nickel ferrite nanoparticle composite layers were characterized using field emission electron microscopy, energy dispersive spectroscopy, and X-ray diffraction spectroscopy. The polymer composite was used to improve the surface of the gold layer to apply the surface plasmon resonance technique. The sensor detected the ferromagnetic ions down to a level of 0.001 ppm, and the detection of diamagnetic ions was conducted with a limitation of roughly 0.5 ppm. The polymer composite improved the response time of the sensor better than the other polymer composite sensing layers did.
