They used cyclic voltammetry (CV) for electro polymerization to combine CTAB
and MWCNTs on the surface of a pencil graphite electrode (PGE). Square wave
voltammetry (SWV) was used to analyze the sensor performance for BPA detection.
Low LOD value of 134 pM was obtained and effective performance in real matrices
were also reported.
In their work, Yang et al. (2018b) reported sensitive SERS-based BPA detection
in milk samples using nanosensor developed with halides modified Au NPs with
Zn
2+ as aggregation agents. BPA detection at trace levels was achieved using the
sensor. Though, they reported this sensor for detection in milk samples, but such
methods can also be employed for environmental samples.
Nitro-aromatic compounds (NACs) such as nitrobenzene, 4-nitrophenol (4-NP),
mononitrotoluenes (MNTs), di- and trinitrotoluenes (DNTs and TNTs) are widely
used organic compounds having numerous industrial applications like in explosives,
pesticides, pharmaceuticals and dyes manufacturing industries. These are harmful
carcinogenic chemicals. Detection of these compounds from the environmental
samples is crucial. Numerous research works are based on electrochemical detection
of NACs as a result of the electrochemical activity of these compounds due to the
presence of nitro- functional group. Some recent developments in electrochemical
nanosensors for the detection of NACs have been discussed in this section.
Nitrobenzene (NB) falls under the category of NACs and it has been certified as
major pollutant by USEPA. NB has poor wastewater biodegradability, and can result
in methemoglobinemia, and even death. For electrochemical detection of NB,
Emmanuel et al. (2013) reported GCE modified with AuNPs synthesized at room
temperature by green method using Acacia nilotica extract. The analyte was electrochemically analyzed using DPV method and exhibited trace level detection of NB
with low LOD value of 0.016 μM. The nanosensor also displayed appreciable NB
detection in real water samples.
4-Nitro phenol (4-NP) is another harmful phenol based compound, it also falls
under the category of nitro-aromatic compounds. 4-NP is widely used in
pharmaceuticals, dyes and pesticides. 4-NP has long-term stability and once
discharged into the environment, they remain there for a long time, making them
harmful for humans, plants and animals. Exposure to 4-NP can cause undesirable
health issues. In waste water, USEPA have confined maximum limit of 4-NP
concentration as <0.14 μM. Hence, development of effective methods for 4-NP is
necessary. Recently, Zhang et al. (2017a) reported electrochemical nanosensor for
4-NP, fabricated using glassy carbon electrode (GCE) modified with silver
nanowires-polyaniline (AgNWs-PANI) composite. The composite was fabricated
by a two-step method. The sensor was used for sensitive detection of 4-NP with low
LOD value of 52 nM. Effective 4-NP determination was also reported in real water
samples. Jiao et al. (2013) also reported GCE modified with gold-graphene
nanocomposite film for highly sensitive electrochemical detection of 4-NP. The
nanosensor was fabricated using electrochemical co-reduction of tetrachloroauric
acid and graphene oxide on GCE using cyclic voltammetry (CV) technique. Linear
sweep voltammetry (LSV), CV, chronocoulometry and electrochemical impedance
spectroscopy (EIS) methods were used to determine electrochemical behaviour of
5 Development of Environmental Nanosensors for Detection Monitoring. . .
131
and MWCNTs on the surface of a pencil graphite electrode (PGE). Square wave
voltammetry (SWV) was used to analyze the sensor performance for BPA detection.
Low LOD value of 134 pM was obtained and effective performance in real matrices
were also reported.
In their work, Yang et al. (2018b) reported sensitive SERS-based BPA detection
in milk samples using nanosensor developed with halides modified Au NPs with
Zn
2+ as aggregation agents. BPA detection at trace levels was achieved using the
sensor. Though, they reported this sensor for detection in milk samples, but such
methods can also be employed for environmental samples.
Nitro-aromatic compounds (NACs) such as nitrobenzene, 4-nitrophenol (4-NP),
mononitrotoluenes (MNTs), di- and trinitrotoluenes (DNTs and TNTs) are widely
used organic compounds having numerous industrial applications like in explosives,
pesticides, pharmaceuticals and dyes manufacturing industries. These are harmful
carcinogenic chemicals. Detection of these compounds from the environmental
samples is crucial. Numerous research works are based on electrochemical detection
of NACs as a result of the electrochemical activity of these compounds due to the
presence of nitro- functional group. Some recent developments in electrochemical
nanosensors for the detection of NACs have been discussed in this section.
Nitrobenzene (NB) falls under the category of NACs and it has been certified as
major pollutant by USEPA. NB has poor wastewater biodegradability, and can result
in methemoglobinemia, and even death. For electrochemical detection of NB,
Emmanuel et al. (2013) reported GCE modified with AuNPs synthesized at room
temperature by green method using Acacia nilotica extract. The analyte was electrochemically analyzed using DPV method and exhibited trace level detection of NB
with low LOD value of 0.016 μM. The nanosensor also displayed appreciable NB
detection in real water samples.
4-Nitro phenol (4-NP) is another harmful phenol based compound, it also falls
under the category of nitro-aromatic compounds. 4-NP is widely used in
pharmaceuticals, dyes and pesticides. 4-NP has long-term stability and once
discharged into the environment, they remain there for a long time, making them
harmful for humans, plants and animals. Exposure to 4-NP can cause undesirable
health issues. In waste water, USEPA have confined maximum limit of 4-NP
concentration as <0.14 μM. Hence, development of effective methods for 4-NP is
necessary. Recently, Zhang et al. (2017a) reported electrochemical nanosensor for
4-NP, fabricated using glassy carbon electrode (GCE) modified with silver
nanowires-polyaniline (AgNWs-PANI) composite. The composite was fabricated
by a two-step method. The sensor was used for sensitive detection of 4-NP with low
LOD value of 52 nM. Effective 4-NP determination was also reported in real water
samples. Jiao et al. (2013) also reported GCE modified with gold-graphene
nanocomposite film for highly sensitive electrochemical detection of 4-NP. The
nanosensor was fabricated using electrochemical co-reduction of tetrachloroauric
acid and graphene oxide on GCE using cyclic voltammetry (CV) technique. Linear
sweep voltammetry (LSV), CV, chronocoulometry and electrochemical impedance
spectroscopy (EIS) methods were used to determine electrochemical behaviour of
5 Development of Environmental Nanosensors for Detection Monitoring. . .
131