Using Molecular Chiral Recognition to Select a Hplccsp

The chiral recognition mechanism presented in Figure 5 can be broken down into its separate parts if one remembers that these parts are interdependent and cannot exist apart from one another. The advantage of considering the steps independently is that it allows for the development of a system for the classification of HPLC-CSPs. If one considers that the key chromatographic step in the chiral recognition process is the formation of the diastereomeric solute-CSP complex, the current HPLC-CSPs can be broken down into five basic types on the basis of the solute-CSP bonding interactions. Using these classes and the molecular structure of the solute, one or more HPLC-CSPs can be selected for the required enan-tioselective separations. The resulting classes of CSPs are:

• Type I: when the solute-CSP complexes are formed by attractive interactions, such as hydrogen bonding, n-n, dipole stacking, etc., between the solute and CSP. The Pirkle type of CSPs are included in this category

• Type II: when the primary mechanism for the formation of the solute-CSP complex is through attractive interactions, but inclusion complexes also play an important role. The cellulosic and amylosic CSPs are included in this category

• Type III: when the primary mechanism for the formation of the solute-CSP complex is through the formation of inclusion complexes, wherein the sample enters a chiral cavity within the

CSP. The cyclodextrin CSPs are included in this category

• Type IV: when the solute is part of diastereomeric metal complex-chiral ligand-exchange chromato-graphy

• Type V: when the CSP is a protein and the solute-CSP complexes are based on combinations of hydrophobic and polar interactions. CSPs based on immobilized a-acid glycoprotein, bovine and human serum albumin and enzymes such as chymotrypsin are included in this category

Solar Panel Basics

Solar Panel Basics

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