large electrical and active chemical properties. Application of surfactants having anti
fouling properties proved to be major step in determination of phenolic compounds
electrochemically. One such experiment involved CTAB (cetyltetramethylammonium bromide) in the analysis of bisphenol A in water samples obtained from
sewages [66]. Dihydroxybenzene determination was done Multi walled Carbon
Nanotubes (MWCNTs) and Gold nanoparticles (AuNPs) based SPEs; coating of
MWCNTs increased the sensitivity while AuNPs provided conductivity to the surface
[67]. Immobilization of enzyme (polyphenol oxidase) on MWCNTs modified electrode surface was done using electrodeposition techniques. Aiding of Bi
3+
, PPO and
MWCNTs was used for phenol detection and spunning Diaminobenzene (DAB) for
the detection and determination of DAB [68, 69]. Disposable biosensors with magnetic nanoparticles of Nickel for determination of bisphenol A [70]. Surface enhanced
Raman scattering (SERS) enhanced Silver deposited SPEs was used for detection of
phenolic compounds. They are highly efficient for qualitative as well as quantitative
determination of polar organic compounds with very low detection limits (0.1 nM)
[71]. Aetylcholinesterase (AChE) immobilized SPEs with magnetic nanoparticles
were used for determination of pesticides (as they inhibit the enzymatic activities).
AuNPs were added to enhance the stability of Iron oxide nanoparticles. These are
easily renewable electrodes and can be replenished after the removal of magnetic
portion [72]. Methyl parathion is determined by using E. coli immobilized SPEs.
Electrochemical stripping analysis (ESA) esp. ASVs is most common method
for the determination of toxic metal ions. Combining ASVs with SPEs increases
sensitivity, robustness reduces response time and cost of electrochemical detection
[73]. Some of the metal ions detection techniques are mentioned as below:
1. Lead: Sensitivity of the electrochemical detectors is mainly increased by using
Carbon, Bismuth, Gold or other materials. Bismuth, because of their environment friendly nature and high analytical performances are most widely used
technique for lead determination. The wide negative potential window and less
necessity for the removal of dissolved oxygen increase easier handling and their
more convenient use [74–77]. Thin film Hg electrode was also found effective
for microlevel detection of Pb(II) ions [78].
2. Cadmium: Quasi noble behavior of Mercury makes it suitable for application
over a wide range of pH. This holds an additional advantage over Bismuth
which is easily hydrolyzed in neutral or alkaline media. Stripping voltammetry
using mercury electrode can be used for a wide range of metal ion detection and
requires low analysis time without degassing. So it is much beneficial for
determination of trace metals but the only shortcoming associated with metal
toxicity. This requires the development of new techniques to reduce the amount
of mercury used for determination [79]. Ex-situ deposited Hg based SPEs,
AuNPs amalgam and Microelectrode array of Hg are some of the most common
modifiers for detection of Cadmium [34, 80, 81, 82].
3. Mercury: Bare or modified Au electrodes are mainly used in detection of Hg(II)
ions because of the high affinity of gold which increases the preconcentration
and thereby reducing time of detection. However the only drawback that limits
172
A. Ojha
fouling properties proved to be major step in determination of phenolic compounds
electrochemically. One such experiment involved CTAB (cetyltetramethylammonium bromide) in the analysis of bisphenol A in water samples obtained from
sewages [66]. Dihydroxybenzene determination was done Multi walled Carbon
Nanotubes (MWCNTs) and Gold nanoparticles (AuNPs) based SPEs; coating of
MWCNTs increased the sensitivity while AuNPs provided conductivity to the surface
[67]. Immobilization of enzyme (polyphenol oxidase) on MWCNTs modified electrode surface was done using electrodeposition techniques. Aiding of Bi
3+
, PPO and
MWCNTs was used for phenol detection and spunning Diaminobenzene (DAB) for
the detection and determination of DAB [68, 69]. Disposable biosensors with magnetic nanoparticles of Nickel for determination of bisphenol A [70]. Surface enhanced
Raman scattering (SERS) enhanced Silver deposited SPEs was used for detection of
phenolic compounds. They are highly efficient for qualitative as well as quantitative
determination of polar organic compounds with very low detection limits (0.1 nM)
[71]. Aetylcholinesterase (AChE) immobilized SPEs with magnetic nanoparticles
were used for determination of pesticides (as they inhibit the enzymatic activities).
AuNPs were added to enhance the stability of Iron oxide nanoparticles. These are
easily renewable electrodes and can be replenished after the removal of magnetic
portion [72]. Methyl parathion is determined by using E. coli immobilized SPEs.
Electrochemical stripping analysis (ESA) esp. ASVs is most common method
for the determination of toxic metal ions. Combining ASVs with SPEs increases
sensitivity, robustness reduces response time and cost of electrochemical detection
[73]. Some of the metal ions detection techniques are mentioned as below:
1. Lead: Sensitivity of the electrochemical detectors is mainly increased by using
Carbon, Bismuth, Gold or other materials. Bismuth, because of their environment friendly nature and high analytical performances are most widely used
technique for lead determination. The wide negative potential window and less
necessity for the removal of dissolved oxygen increase easier handling and their
more convenient use [74–77]. Thin film Hg electrode was also found effective
for microlevel detection of Pb(II) ions [78].
2. Cadmium: Quasi noble behavior of Mercury makes it suitable for application
over a wide range of pH. This holds an additional advantage over Bismuth
which is easily hydrolyzed in neutral or alkaline media. Stripping voltammetry
using mercury electrode can be used for a wide range of metal ion detection and
requires low analysis time without degassing. So it is much beneficial for
determination of trace metals but the only shortcoming associated with metal
toxicity. This requires the development of new techniques to reduce the amount
of mercury used for determination [79]. Ex-situ deposited Hg based SPEs,
AuNPs amalgam and Microelectrode array of Hg are some of the most common
modifiers for detection of Cadmium [34, 80, 81, 82].
3. Mercury: Bare or modified Au electrodes are mainly used in detection of Hg(II)
ions because of the high affinity of gold which increases the preconcentration
and thereby reducing time of detection. However the only drawback that limits
172
A. Ojha