o AAS (Water and therapeutic mud) o AAS (Seawater) o GF-AAS (Chinese tea) o GF-AAS (Wine) o ASF (Brown rice) o Potentiometry (Multiwalled carbon nanotubes functionalized by dithizonemodified electrode) o PVC-based polyaniline Sn(IV) silicate composite cation exchanger ionselective membrane electrode The current method uses a biosensor that detects changes in temperature, unlike the previous methods which used various spectroscopy techniques, potentiometry, and amperometric methods.