## 2 Impedance Spectroscopy
### Scopes of Application
#### 2.1.1 IS in Human Health Safety Due to Water Sources Contamination
[41] determined ochratoxin mycotoxin (mycotoxins are toxic secondary metabolites produced by fungi capable of causing diseases and death in both humans and animals) using a thiolated DNA aptamer (aptamers are artificial short sequences of _Deoxyribonucleic_ acid, DNA, _Ribonucleic_ acid, RNA, _Xeno Nucleic_ Acid, XNA, or of short protein chains, named peptides, that bind a specific target molecule, or family of molecules), immobilized by chemisorption to the surface of an Au electrode, which they stimulated by EIS (a standard three-cell was utilized, consisting of a gold working electrode, a Pt wire auxiliary electrode, and an Ag/AgCl/1 M KCl reference electrode; measurements were taken in a frequency range of 0.1 Hz-100 kHz, using an AC voltage of 5 mV combined with a DC one of 0.165 mV). [PERSON] et al. 's team carried out their initial work and detected other mycotoxins, such as Aflatoxin B1 using a layer coating of cystamine, poly (amido-amine) dendrimers (polymeric nanoparticles) of generation 4.0 (PAMAM G4), and DNA aptamers on Au electrodes, once again employing EIS (measures were done in the frequency range from 0.1 Hz to 100 kHz, while applying 5 mV amplitude AC voltage with DC component of 0.22 V, using a standard EIS cell composed of a gold working gold electrode, an Ag/AgCl/1 M KCl reference electrode, and a Pt wire auxiliary electrode) [42]. In their turn, [PERSON] and colleagues [43] evaluated pesticides presence, such as acetamipid, in samples of vegetables (tomatoes and cucumbers) using AgNP-modified nitrogen-doped graphene (AgNP stands for Argentina Nanoparticles); the developed aptasensor (an aptasensor is a biosensor which recognizes biological elements like DNA or RNA aptamer) evaluated by EIS (for the experimental characterization, frequencies in between 0.01 Hz and 10 kHz were applied, with an AC voltage amplitude of 5 mV; a glassy carbon working electrode, a saturated calomel reference electrode, and a platinum wire counter electrode composed the conventional three-electrode system used), was sensitive, selective, and economical, and did not require intricate labelling procedures. Gold nanoparticles (GNPs) electrodes (modified screen-printed carbon electrode), developed by [PERSON] and co-authors [44], were used on another aptasensor, also assessed by EIS (measurementswere conducted at room temperature, in the frequency range of 0.1 Hz to 100 kHz, using an AC voltage of 5 mV amplitude combined with a DC component of 250 mV, and a three-electrode configuration printed on a ceramic substrate). For the mensurations, a GNPs-SPCE working electrode (a gold nanoparticles-modified, screen-printed carbon electrode), a carbon counter electrode, and a silver pseudo-reference electrode were combined for tracing _Salmonella_ (_Salmonella_ is a genus of rod-shaped, gram-negative bacteria of the family _Enterobacteriaceae_); the sensor displayed selectivity to _Salmonella enteritidis_ (present in pork products and globally responsible for a high number of human infections around the world) and showed a negative response towards the mixture of other pathogens. [PERSON] et al. [45] also fabricated a _Salmonella enterica serovar Typhimurium_ sensor using glass carbon electrodes (GCE) modified by graphene oxide/Gold-mixed nanoparticles (GO/Au NPs-modified GCE); they used EIS to evaluate the sensor against pork samples, for which it achieved a limit of detection of 3.0 colony-forming units (CFU mL\({}^{-1}\)). Pharmaceutically active materials also stand as significant aquatic pollutants; when released into the water systems, they are of major concern, and several drugs' existence in diverse forms/systems was evaluated using IS, intending to avoid their release into water systems (managing the systems containing the drugs differently, without disposing of them in water systems).