Gas chromatography is also used for organochlorinated pesticide detection.
Vojtech et al. [93] have used polyetherimide nanofibers as sorbents or solid phase
microextraction tool and these fibers were then tested in gas chromatograph. They
claim that fast sorption and ease of production along with their ability to be utilized
for detection of organochlorinated pesticide make these nanofibers a choice material
for SPMEs.
Electrochemical sensors also see great potential in nanofibers due to their shape
and size. An amperometric biosensor for determining the organophosphate pesticides(parathion) in aqueous system was developed by Bao et al. [94] The biosensor
utilizes TiO 2 nanofibers and multiwalled carbon nanotubes along with other entities
as sensing platform and is able to detect organophosphate pesticides with a wide
linear range, less than 5 s response time and detection limit as low as 10 nM for
parathion. Dai et al. [95] have also used the electrochemical technique for determining methyl parathion concentration using electrospun zirconia-embedded carbon nanofiber. The reported detection limit is 3.4 g L
−1 , which is much lower than
many other reported non-nanofiber-based electrodes [95]. Another example of
utilizing nanofiber as template for active material is the work of Oliveira et al. They
have modified nylon nanofibers with layer-by-layer deposition of polypyrrole and
poly(o-ethoxyaniline) and assembled it over the graphite interdigitated electrode.
A flow analysis system was developed and it was able to distinguish between
contaminated and clear water. The electronic tongue apparatus, as they call it, was
able to detect paraoxon, a pesticide in water up to 2.5 ppb concentration. Malathion
is another organophosphorus pesticide which can be detected using a polyaniline
nanofiber and single carbon nanotube composite modification of graphite interdigitated electrodes. The reported minimum detection limit is 2 Â 10
−7 M [89]. We
can see that Carbon nanotubes have been extensively used as a modifier for the
nanofibers and the fabrication of electrode for pesticide sensing using electrochemical sensors [89].
3.8 Biological Contaminants
The microbial world consists of a plethora of different types or classes of microbial
agents which can be potentially present in water [96]. The biological contaminants
like virus, bacteria, protozoans, fungi, and algae are widespread in the environment
around us and are harmless until they get access to the internal sites in a body in
sufficiently high concentrations. This access is often through drinking contaminated
water and those with immunodeficiency due to some reason are more susceptible to
it. Therefore, recognition and identification of a possible waterborne pathogen is
extremely important and there are a variety of ways to achieve this [8]. As mentioned earlier, the microbes present in the environment are fully capable of
infecting, colonizing, and initiating illness in humans, provided they are able to
enter our body and multiply within it. As per the EPA standards, total coliforms
should be less than 5% in drinking water. There are a variety of techniques
312
A. K. Srivastava et al.
Vojtech et al. [93] have used polyetherimide nanofibers as sorbents or solid phase
microextraction tool and these fibers were then tested in gas chromatograph. They
claim that fast sorption and ease of production along with their ability to be utilized
for detection of organochlorinated pesticide make these nanofibers a choice material
for SPMEs.
Electrochemical sensors also see great potential in nanofibers due to their shape
and size. An amperometric biosensor for determining the organophosphate pesticides(parathion) in aqueous system was developed by Bao et al. [94] The biosensor
utilizes TiO 2 nanofibers and multiwalled carbon nanotubes along with other entities
as sensing platform and is able to detect organophosphate pesticides with a wide
linear range, less than 5 s response time and detection limit as low as 10 nM for
parathion. Dai et al. [95] have also used the electrochemical technique for determining methyl parathion concentration using electrospun zirconia-embedded carbon nanofiber. The reported detection limit is 3.4 g L
−1 , which is much lower than
many other reported non-nanofiber-based electrodes [95]. Another example of
utilizing nanofiber as template for active material is the work of Oliveira et al. They
have modified nylon nanofibers with layer-by-layer deposition of polypyrrole and
poly(o-ethoxyaniline) and assembled it over the graphite interdigitated electrode.
A flow analysis system was developed and it was able to distinguish between
contaminated and clear water. The electronic tongue apparatus, as they call it, was
able to detect paraoxon, a pesticide in water up to 2.5 ppb concentration. Malathion
is another organophosphorus pesticide which can be detected using a polyaniline
nanofiber and single carbon nanotube composite modification of graphite interdigitated electrodes. The reported minimum detection limit is 2 Â 10
−7 M [89]. We
can see that Carbon nanotubes have been extensively used as a modifier for the
nanofibers and the fabrication of electrode for pesticide sensing using electrochemical sensors [89].
3.8 Biological Contaminants
The microbial world consists of a plethora of different types or classes of microbial
agents which can be potentially present in water [96]. The biological contaminants
like virus, bacteria, protozoans, fungi, and algae are widespread in the environment
around us and are harmless until they get access to the internal sites in a body in
sufficiently high concentrations. This access is often through drinking contaminated
water and those with immunodeficiency due to some reason are more susceptible to
it. Therefore, recognition and identification of a possible waterborne pathogen is
extremely important and there are a variety of ways to achieve this [8]. As mentioned earlier, the microbes present in the environment are fully capable of
infecting, colonizing, and initiating illness in humans, provided they are able to
enter our body and multiply within it. As per the EPA standards, total coliforms
should be less than 5% in drinking water. There are a variety of techniques
312
A. K. Srivastava et al.