. 2019 Nov 3;19(21):4781. doi: 10.3390/s19214781

Table 2.

Comparison of electrochemical methods.

Electrochemical Methods
Target Analyte	Detection Principle	Sensing Element	Sensing Material	Substrate	LOD	Real Sample	Ref.
Hg⁺²	ASV	Electrode system	WE: Au	PDMS	3 ppb	No	[101]
			CE: Au
			RE: Ag
Pb⁺² and Hg⁺²	CV	Electrode system	WE: carbon	Polyethylene terephthalate	50 $μ$ M each	No	[104]
			CE: Ag
			RE: Ag/Cl
Pb⁺²	SWASV	Electrode system	WE: Ag	Polymer	0.55 ppb	No	[99]
Pb⁺²	SWASV	Electrode system	CE/QRE: Ag	Polymer	0.55 ppb	No	[99]
Pb⁺² and Hg⁺²	SWASV	Electrode system	WE: carbon	Paper	2.0 and 2.3 ppb, resp. water	Soda water and dirty ground	[111]
			CE: carbon
			RE: Ag pseudo
As	CV	Electrode system	WE: Ag	Plastic	1 ppb	No	[102]
			CE: Carbon
			RE: Ag/AgCl
As	SWASV	Electrode system	WE: Au/SWCNT	PDMS	4.5 ppb	No	[103]
As	SWASV	Electrode system	CE and RE: SWCNT	PDMS	4.5 ppb	No	[103]
As(III)	Amperometry	Bioreporter with electrode system	WE: Au	Plastic	0.8 ppb	Tap and ground water	[112]
As(III)	Amperometry	Bioreporter with electrode system	CE and RE: Ag and E. coli	Plastic	0.8 ppb	Tap and ground water	[112]
Nitrate	CV	Electrode system	WE and RE: Ag	Glass	25 ppb		[113]
Nitrate	CV	Electrode system	CE: Au	Glass	25 ppb		[113]
Nitrate	CV	Electrode system	WE: Ag	Glass	0.2 ppm	Field and environmental water	[114]
			CE: Au
			RE: Ag
Nitrate and Potassium	Potentiometric	Electrode system	WE: Polymeric membrane	Green tapes	9.56 and 0.81 mg/L, respectively	Water from recycling unit	[115]
Nitrate and Potassium	Potentiometric	Electrode system	RE: Ag/AgCl	Green tapes	9.56 and 0.81 mg/L, respectively	Water from recycling unit	[115]
Nitrate	Potentiometric	Electrode system with modified working electrode	WE: f-MWCNTs RE:Ag/AgCl	Lipophilic carbon nanotubes	$5 \times 10$ ⁻⁷ M	Desalinated seawater	[116]
Nitrate	EIS	Electrode system with modified working electrode	WE: NiR/nTiO2-GF CE: Au RE: Ag/AgCl	PDMS	1 $μ$ M	No	[117]
Nitrate and Nitrite	SWV	Electrode system with modified working electrode	WE: Cu/MWCNT/RGO/GCE CE: Pt-wire RE: Ag/AgCl	GCE	20 and 30 nM, resp.	Tap and mineral water	[77]
E. coli	Voltammetry	Electrode system with modified working electrode	WE: immobilized DNA probe on Au CE and RE: Pt	Glass	100 nM	No	[118]
Hepatitis B	ASV	Electrode system	WE: GCE CE: Pt wire RE: Ag/AgCl and DNA modified AgNP	Paper	85 pM	No	[119]
E. coli	Amperometry	Immunoassays	Antibody	PMMA	50 CFU/mL	Real sample	[120]
E.coli	Positive dielectrophoresis	Sensing and focusing electrode	Not specified	PDMS	300 CFU/mL	No	[121]
E. coli	EIS	Interdigitated electrodes	Modified silicon sensor chip	Silicon and PDMS	10 cells/mL	No	[122]
E. coli and S. aureus	EIS	Coplanar electrode	Au electrode	Silicon	522 cells/mL	No	[123]
E. coli and Enterococci	Coulter principle	Microfluidic sensing chip	Resistance detection circuit	PDMS	Individual cell	Ballast water sample	[124]
Salmonella typhimurium	Impedance analyzer	Interdigitated electrodes	Au electrode with immobilized antibodies	PDMS	$3 \times 10$ ³ CFU/mL	No	[125]

LOD: Limit of detection; ASV: Anodic stripping voltammetry; PDMS: Polydimethylsiloxane; PMMA: Poly(methyl methacrylate); CV: Cyclic voltammetry; SWASV: Square-wave anodic stripping voltammetry; QRE: Quasi-reference electrode; WE:Working electrode; CE: Counter electrode; RE: Reference electrode; EIS: Electrochemical impedance spectroscopy; SWV: Square-wave voltammetry; RGO: Reduced graphene oxide; GCE: Glassy carbon electrode; -MWCNTs: Functionalised- multiwall carbon nanotube.