Measuring quality of chromatogram – Tools 1.0

Lead In the previous post, we talked about choosing suitable initial conditions when developing a new liquid chromatography (LC) method. The possibility of a successful separation is increased by selecting the appropriate column conditions and mobile phase composition. Getting the controls that quantitatively measure the separation’s quality is another crucial step in the method development process. Although the majority of chromatographers are able to assess the separation quality from a chromatogram, it is critical to …

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Selecting the tools

Lead Starting out with a sound strategy is one of the most important aspects of minimizing chromatographic separation issues. A good method makes it much simpler to maintain operation within parameters and address issues as they appear. Selecting the right tools is very critical to achieve the best results,. By looking at the cause-and-effect diagram given below one can understand the factors that influence chromatographic separation. Basically the factors falls into two major categories namely …

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HPLC Method Development – prelude

Lead Many chromatographers develop HPLC separations on a daily basis. The philosophy behind method development is founded on a number of factors. Today, chromatographic separation and how it varies depending on the sample and experimental conditions have a good practical understanding. This understanding of the chromatographic process should serve as the foundation for any methodological approach to HPLC method development. Most of the time, a desired separation can be easily accomplished with a minimal number …

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Protein-based CSPs

Lead Proteins are complex, high-MW biopolymers composed of L-amino acids and possess ordered 3D-structure. They are known to bind /interact  stereoselectively with small molecules  reversibly, making them extremely versatile CSPs for chiral separation of drug molecules.   Number of CSPs has been developed by immobilizing proteins. These type of CSPs operate under RP-mode; (phosphate buffer and organic modifiers)   Characteristics of proteins used in commercial CSPs Mechanism Protein polymer remains in twisted form because of the …

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Donor-Acceptor (Pirkle)-type CSPs

Lead William H Pirkle developed these CSPs and are  based on the ionic or covalent attachment of one enantiomer of an amino acid derivative to aminopropyl silica. Pirkle phases contain π-electron donor or acceptor rings substituted with H-bonding moieties. Donor–acceptor-type CSPs capitalize on synthetic or semi-synthetic chiral low-molecular-weight chiral selectors capable of recognizing chiral analytes by complementary assembly of nonionic attractive interactions. Basic design and types Generally speaking a chiral phase of the Pirkle type …

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Cyclodextrin-based CSPs

Lead Cyclodextrin-based CSP belongs to the cavity type. Armstrong is considered the father of cyclodextrin-based CSPs. CDs are employed in various fields of analytical chemistry, due to their tendency to form reversible inclusion complexes and recognize chiral analytes. CDs are a type of macrocyclic D-(+)-glucopyranose oligomers linked by α-1,4-glycosidic linkages, as seen in Figure, under chemistry . The relevant oligomers for liquid chromatographic enantiomer separation are composed of 6(α-CD), 7(β-CD), and 8(γ-CD) monosaccharide units, in that order. …

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Polysaccharide-based CSPs

  Lead Surprisingly, chiral chromatography could not be performed in 1980 because there was no single chiral stationary phase on the market. But as the 1980s came to a close, chiral chromatography began to get more and more attention, thanks in large part to the efforts of Okamoto’s institute in Japan, Pirkle and Armstrong’s teams in the US, Schurig and König in Germany, Lindner in Austria, and Francotte in Switzerland. The most prevalent chiral polymers …

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Chiral selectors

Lead A wide range of chiral compounds have been examined as chiral selectors with regard to their ability to separate enantiomers using chromatography as part of the development of CSPs. From low-molecular-weight chemicals to polymers with both synthetic and biological origins, the chiral molecules investigated as potential CSs span almost the full spectrum of chemical and structural diversity. The search for effective CSs has so far led to the synthesis of more than 1400 CSPs, …

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Direct chiral HPLC separation on CSPs

Chiral stationary phases (CSPs) The most convenient and most popular analytical methodology to assess chiral purity is the direct separation of enantiomers on so-called chiral stationary phases (CSPs). CSPs consists of an (ideally) inert chromatographic support ( usually silica micro-particles) on to which the chiral selector (CS; single enantiomer of a chiral molecule) is physically coated (adsorption) or immobilization (covalently linked).   Basic concept The column is packed with a chiral selector (viz. polysaccharide or …

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Chiral HPLC separation: strategy and approaches

Strategy The basic aspect is to provide the right chiral environment where by the enantiomeric pair become distinguishable. In HPLC how do we construct the chiral environment? To understand this let us look at the variables available, in the HPLC system, that can be exploited for this purpose. The following is a schematic diagram of a typical HPLC system. The are three variables namely the analyte, mobile phase and stationary phase that can be alerted …

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