et al. 2016; Wang et al. 2016; Zhao et al. 2018; Coelho et al. 2019). The detection of
the pollution sources of the chiral pollutants is also a challenge. As a result, it may
become difficult to identify the non-point sources of the pollution (Ali and AboulEnein 2002; Aboul-Enein and Ali 2004; Ali et al. 2008a, b; Elbashir and AboulEnein 2018).
The enantioselective analysis of the respective compounds is one of the most
important issues when it comes to fate and transformation research of chiral pollutants. Different analytical methods have been used to analyse chiral pollutants. These
are discussed in-length earlier in this monograph. Meanwhile, it was realised that the
discussed methods are capable of separating and identifying any type of the chiral
pollutants having one asymmetric centre only. But still there are certain restrictions
and challenges in this area. The concentration of the chiral pollutants in the atmosphere can be mainly determined by chromatographic separation. It is important to
mention again here that the chiral stationary phases (CSPs) in GC as well as LC are
usually highly selective compounds, especially when it comes to enantioselectivity;
in most cases, they do not cover all theoretically relevant groups of the chiral
pollutants. Therefore, it is difficult to analyse all types of the chiral pollutants in
the atmosphere with only a limited selection of chiral stationary phases (CSP)
available for cGC today. Furthermore, it may be also an analytical challenge to
separate and identify the enantiomers of chiral pollutants having more than one
chiral centre (Ali et al. 2016d, e; Camacho-Munoz et al. 2019; Phyo et al. 2020).
11.3 Future Directions and Method Requirements
These restrictions and challenges may be handled in future by developing new
approaches and technologies. In order to eliminate the problems connected with
the bioaccumulation of toxic chiral pollutants in the living systems, substantial
attention should be paid to their bioaccumulation mechanisms for ensuring better
and safer applications. Of course, chirality is an inherent property of the molecules,
which may be due to stereogenic centres, axial or planar asymmetries forming the
inseparable basic topology of the chiral molecules as shown above in detail. Therefore, we need to look into the proper optimisation and control of other parameters to
bring down the hazards due to bioaccumulation of the chiral pollutants. The
enantioselective behaviour of the chiral pollutants should be taken into consideration
when making an environmental assessment of the chiral pollutants. Sometimes, the
chiral pollutants have weak enantioselectivities but significant enantioselectivities
may be induced by biological factors. A reasonable explanation for such increases in
enantioselectivities of the chiral pollutants needs further investigation due to the still
considerable lack of adequate knowledge of enzyme systems in the organisms. In
order to improve the knowledge on such interaction mechanisms of the chiral
pollutants, bioaccumulation-related events (using particular technological platforms), careful experimental design, high-resolution data acquisition, robust data
11.3 Future Directions and Method Requirements
309
the pollution sources of the chiral pollutants is also a challenge. As a result, it may
become difficult to identify the non-point sources of the pollution (Ali and AboulEnein 2002; Aboul-Enein and Ali 2004; Ali et al. 2008a, b; Elbashir and AboulEnein 2018).
The enantioselective analysis of the respective compounds is one of the most
important issues when it comes to fate and transformation research of chiral pollutants. Different analytical methods have been used to analyse chiral pollutants. These
are discussed in-length earlier in this monograph. Meanwhile, it was realised that the
discussed methods are capable of separating and identifying any type of the chiral
pollutants having one asymmetric centre only. But still there are certain restrictions
and challenges in this area. The concentration of the chiral pollutants in the atmosphere can be mainly determined by chromatographic separation. It is important to
mention again here that the chiral stationary phases (CSPs) in GC as well as LC are
usually highly selective compounds, especially when it comes to enantioselectivity;
in most cases, they do not cover all theoretically relevant groups of the chiral
pollutants. Therefore, it is difficult to analyse all types of the chiral pollutants in
the atmosphere with only a limited selection of chiral stationary phases (CSP)
available for cGC today. Furthermore, it may be also an analytical challenge to
separate and identify the enantiomers of chiral pollutants having more than one
chiral centre (Ali et al. 2016d, e; Camacho-Munoz et al. 2019; Phyo et al. 2020).
11.3 Future Directions and Method Requirements
These restrictions and challenges may be handled in future by developing new
approaches and technologies. In order to eliminate the problems connected with
the bioaccumulation of toxic chiral pollutants in the living systems, substantial
attention should be paid to their bioaccumulation mechanisms for ensuring better
and safer applications. Of course, chirality is an inherent property of the molecules,
which may be due to stereogenic centres, axial or planar asymmetries forming the
inseparable basic topology of the chiral molecules as shown above in detail. Therefore, we need to look into the proper optimisation and control of other parameters to
bring down the hazards due to bioaccumulation of the chiral pollutants. The
enantioselective behaviour of the chiral pollutants should be taken into consideration
when making an environmental assessment of the chiral pollutants. Sometimes, the
chiral pollutants have weak enantioselectivities but significant enantioselectivities
may be induced by biological factors. A reasonable explanation for such increases in
enantioselectivities of the chiral pollutants needs further investigation due to the still
considerable lack of adequate knowledge of enzyme systems in the organisms. In
order to improve the knowledge on such interaction mechanisms of the chiral
pollutants, bioaccumulation-related events (using particular technological platforms), careful experimental design, high-resolution data acquisition, robust data
11.3 Future Directions and Method Requirements
309