as well as others (Kubota et al. 2004; Mangelings and Vander Heyden 2008;
Cavazzini et al. 2011; Lammerhofer 2014; Lorenz and Seidel-Morgenstern 2014;
Peluso et al. 2015).
Consequently, during the past 20 years, the number of new CSPs has continuously increased. Today, a number of new selective phases are reported in the
literature (Aboul-Enein and Ali 2003; Mangelings and Vander Heyden 2008;
Schurig and Ciogli 2013; Guo et al. 2016). An abundance of comprehensive reviews
is reporting on the application of these new CSPs also for environmental applications
(Al-Othman et al. 2014; Lammerhofer 2014; Lorenz and Seidel-Morgenstern 2014;
Ribeiro et al. 2014; Mu et al. 2015; Peluso et al. 2015; Badea et al. 2016; Guo et al.
2016; Patel et al. 2016; Sierra et al. 2016; Carrasco-Correa et al. 2017; Francotte
2017; Peluso et al. 2017; Sanganyado et al. 2017; Xie and Yuan 2017; Batra and
Bhushan 2018; Ciogli et al. 2018; Elbashir and Aboul-Enein 2018; Huang et al.
2018b; Ilisz et al. 2018; Zhang et al. 2018). All these overviews have been published
within the past 4 years (updated 2018), impressively demonstrating the recent rapid
progress in research and development in the field of LC-based enantiomer-selective
separation techniques for low-level identification and determination (Hühnerfuss
and Shah 2009).
Although the number of publications about enantiomeric separations and the
number of commercially available chiral stationary phases have expanded substantially, only a few basic types of chiral stationary phases and related selective
interactions are utilised only for the enantiomer-selective separation. Mainly modifications and complex derivatives of basic CSP types are introduced for enantiomer/
chiral compound selective separations. Most of the enantiomeric separations in LC
can be accomplished using six or seven different CSPs. During the early stage of
CSP development, several authors have tried to categorise HPLC-CSP into simplified and distinct classes (Vinter and Saunders 1991; Schug 2007; Okamoto and Ikai
2008; Berthod 2009). In one of these systems developed by Wainer (Wainer and
Alembik 1986a, b; Wainer et al. 1986; Lough 2014), the enantioselective recognition process is divided into two interdependent stages:
• The formation of the solute-CSP complex, represented by interactions A•••A
0 and
B•••B
0 in Fig. 3.1
• The expression of the stereochemical differences between the enantiomorphs
represented by the interactions C•••C
0 and C•••D
0 , respectively.
The mechanisms involved in the first stage are used as a criterion for the division
of HPLC-CSP into groups (Hühnerfuss and Shah 2009).
In detail, the process of enantioselective recognition can be resolved into the
following steps (Pirkle et al. 1984; Hou et al. 1997; Schurig and Mayer 2001;
Berthod 2009), see Fig. 3.1:
1. There exist three possible points of interaction between the chiral solute (sites A
0 ,
B
0 and C
0 ) and the chiral selector bound to the chiral stationary phase (sites A B,
and C).
38
3 Enantiomer-Selective High- and Ultra- High-Performance Liquid Chromatography
Cavazzini et al. 2011; Lammerhofer 2014; Lorenz and Seidel-Morgenstern 2014;
Peluso et al. 2015).
Consequently, during the past 20 years, the number of new CSPs has continuously increased. Today, a number of new selective phases are reported in the
literature (Aboul-Enein and Ali 2003; Mangelings and Vander Heyden 2008;
Schurig and Ciogli 2013; Guo et al. 2016). An abundance of comprehensive reviews
is reporting on the application of these new CSPs also for environmental applications
(Al-Othman et al. 2014; Lammerhofer 2014; Lorenz and Seidel-Morgenstern 2014;
Ribeiro et al. 2014; Mu et al. 2015; Peluso et al. 2015; Badea et al. 2016; Guo et al.
2016; Patel et al. 2016; Sierra et al. 2016; Carrasco-Correa et al. 2017; Francotte
2017; Peluso et al. 2017; Sanganyado et al. 2017; Xie and Yuan 2017; Batra and
Bhushan 2018; Ciogli et al. 2018; Elbashir and Aboul-Enein 2018; Huang et al.
2018b; Ilisz et al. 2018; Zhang et al. 2018). All these overviews have been published
within the past 4 years (updated 2018), impressively demonstrating the recent rapid
progress in research and development in the field of LC-based enantiomer-selective
separation techniques for low-level identification and determination (Hühnerfuss
and Shah 2009).
Although the number of publications about enantiomeric separations and the
number of commercially available chiral stationary phases have expanded substantially, only a few basic types of chiral stationary phases and related selective
interactions are utilised only for the enantiomer-selective separation. Mainly modifications and complex derivatives of basic CSP types are introduced for enantiomer/
chiral compound selective separations. Most of the enantiomeric separations in LC
can be accomplished using six or seven different CSPs. During the early stage of
CSP development, several authors have tried to categorise HPLC-CSP into simplified and distinct classes (Vinter and Saunders 1991; Schug 2007; Okamoto and Ikai
2008; Berthod 2009). In one of these systems developed by Wainer (Wainer and
Alembik 1986a, b; Wainer et al. 1986; Lough 2014), the enantioselective recognition process is divided into two interdependent stages:
• The formation of the solute-CSP complex, represented by interactions A•••A
0 and
B•••B
0 in Fig. 3.1
• The expression of the stereochemical differences between the enantiomorphs
represented by the interactions C•••C
0 and C•••D
0 , respectively.
The mechanisms involved in the first stage are used as a criterion for the division
of HPLC-CSP into groups (Hühnerfuss and Shah 2009).
In detail, the process of enantioselective recognition can be resolved into the
following steps (Pirkle et al. 1984; Hou et al. 1997; Schurig and Mayer 2001;
Berthod 2009), see Fig. 3.1:
1. There exist three possible points of interaction between the chiral solute (sites A
0 ,
B
0 and C
0 ) and the chiral selector bound to the chiral stationary phase (sites A B,
and C).
38
3 Enantiomer-Selective High- and Ultra- High-Performance Liquid Chromatography