the nanosensor for 4-NP detection. The sensor showed high stability, repeatability
and low LOD of 10
À8 M. Direct application was also exhibited in the river water
samples.
Mononitrotoluenes (MNTs) are NACs with one nitro functional groups. These
include, ortho-, para-, and meta-, nitrotoluenes. Out of these three, ortho- or
2-nitrotoluene (2-NT) is most commercially used MNT. It is used as a precursor
for manufacturing of TNT, and in rubber, dyes and agricultural industries. High
exposures of 2-NT can cause health issues like cyanosis, nausea and anoxia. It is also
a potential endocrine disrupting and carcinogenic compound. Recently, Bhanjana
et al. (2018) developed silver oxide (Ag 2 O) QDs-based electrochemical sensor for
detection of 2-NT from laboratory and real samples. CV technique was used for the
analysis and the sensor exhibited highly sensitive detection with over wide linear
range of 5–40 ppm and very low LOD of 4.3 ppm.
NACs like dinitrobenzene (DNB) and 2,4,6 trinitrotoluene (TNT) are explosive
aromatic compounds. Detection of such compounds is important for the areas of
forensics and security. But these chemicals can also enter the water bodies and soil,
and they can penetrate through the skin, causing several chronic health hazards. For
the detection of TNT and DNB, Singh et al. (2016) prepared electrochemical sensor
by electrodisposition of glycine stabilized-Ag NPs on SPE. Analysis was done using
DPV technique. The sensor showed high sensitivity towards TNT detection with a
wide linear range of 1 Â 10
À10 M–0.1 M. DNB was also detected efficiently over the
linear range 1 Â 10
À7 M–0.1 M.
Poly Aromatic Hydrocarbons (PAHs)
Poly aromatic hydrocarbons (PAHs) are hazardous pollutants for air, water and soil.
PAHs are discharged into the environment by activities like incomplete fossil fuel
combustion, incineration of wastes, volcanic eruptions and forest fires, release from
underground petroleum sources and decay of plants. These are carcinogenic, mutagenic and teratogenic chemicals. These are organic chemicals, and their chemical
structure contain two or more aromatic rings fused together, e.g., naphthalene,
anthracene, chrysene, benzo[a]pyrene etc. Contact, inhalation and ingestion of
PAHs can result in potential risk of cancer in humans. PAHs may undergo metabolic
processes leading to the formation of toxic metabolites, which can lead to gene
mutation by attaching to DNA. Exposures to PAHs also possess threat to aquatic
organisms and animals. 16 PAHs are identified as highly toxic by the Environmental
Protection Agency (EPA). Hence, methods for their effective detection are required.
Nanosensors technology has emerged for such applications. For e.g., recently,
Tijunelyte et al. (2017) devised diazonium salt based-SERS nanosensor for detection
of three PAHs i.e., fluoranthene (FL), benzo[a]pyrene (BaP) and naphthalene (NAP).
Au nanorods arrays (commercially available) were functionalized using diazonium
salt (DS-C 10 H 21 ) for fabrication of the nanosensor. The analytes were detected with
LOD values: 0.064 mg L
À1 for FL, 3.94 mg L
À1 for NAP, and 0.026 mg L
À1 for
BaP. The nanosensor was reusable, and used for sensitive, and reproducible detection of PAHs.
132
U. Chakraborty et al.
and low LOD of 10
À8 M. Direct application was also exhibited in the river water
samples.
Mononitrotoluenes (MNTs) are NACs with one nitro functional groups. These
include, ortho-, para-, and meta-, nitrotoluenes. Out of these three, ortho- or
2-nitrotoluene (2-NT) is most commercially used MNT. It is used as a precursor
for manufacturing of TNT, and in rubber, dyes and agricultural industries. High
exposures of 2-NT can cause health issues like cyanosis, nausea and anoxia. It is also
a potential endocrine disrupting and carcinogenic compound. Recently, Bhanjana
et al. (2018) developed silver oxide (Ag 2 O) QDs-based electrochemical sensor for
detection of 2-NT from laboratory and real samples. CV technique was used for the
analysis and the sensor exhibited highly sensitive detection with over wide linear
range of 5–40 ppm and very low LOD of 4.3 ppm.
NACs like dinitrobenzene (DNB) and 2,4,6 trinitrotoluene (TNT) are explosive
aromatic compounds. Detection of such compounds is important for the areas of
forensics and security. But these chemicals can also enter the water bodies and soil,
and they can penetrate through the skin, causing several chronic health hazards. For
the detection of TNT and DNB, Singh et al. (2016) prepared electrochemical sensor
by electrodisposition of glycine stabilized-Ag NPs on SPE. Analysis was done using
DPV technique. The sensor showed high sensitivity towards TNT detection with a
wide linear range of 1 Â 10
À10 M–0.1 M. DNB was also detected efficiently over the
linear range 1 Â 10
À7 M–0.1 M.
Poly Aromatic Hydrocarbons (PAHs)
Poly aromatic hydrocarbons (PAHs) are hazardous pollutants for air, water and soil.
PAHs are discharged into the environment by activities like incomplete fossil fuel
combustion, incineration of wastes, volcanic eruptions and forest fires, release from
underground petroleum sources and decay of plants. These are carcinogenic, mutagenic and teratogenic chemicals. These are organic chemicals, and their chemical
structure contain two or more aromatic rings fused together, e.g., naphthalene,
anthracene, chrysene, benzo[a]pyrene etc. Contact, inhalation and ingestion of
PAHs can result in potential risk of cancer in humans. PAHs may undergo metabolic
processes leading to the formation of toxic metabolites, which can lead to gene
mutation by attaching to DNA. Exposures to PAHs also possess threat to aquatic
organisms and animals. 16 PAHs are identified as highly toxic by the Environmental
Protection Agency (EPA). Hence, methods for their effective detection are required.
Nanosensors technology has emerged for such applications. For e.g., recently,
Tijunelyte et al. (2017) devised diazonium salt based-SERS nanosensor for detection
of three PAHs i.e., fluoranthene (FL), benzo[a]pyrene (BaP) and naphthalene (NAP).
Au nanorods arrays (commercially available) were functionalized using diazonium
salt (DS-C 10 H 21 ) for fabrication of the nanosensor. The analytes were detected with
LOD values: 0.064 mg L
À1 for FL, 3.94 mg L
À1 for NAP, and 0.026 mg L
À1 for
BaP. The nanosensor was reusable, and used for sensitive, and reproducible detection of PAHs.
132
U. Chakraborty et al.