The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Beltran, Sea food) o XRFS (Soil sample) o Amperometric method (Glucose oxidase-functionalized cobalt oxidemodified glassy carbon electrode) The current method uses a biosensor that detects changes in temperature, unlike the previous methods which used various spectroscopy techniques and amperometric methods.