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Techniques & methodologies
Chiralabs uses a variety of spectroscopic, physicochemical and chromatographic techniques, including those briefly described below (for in-depth descriptions see Literature). We offer a contract service that can provide from just a "one-off" study through to a comprehensive service on a call-off, contract or project basis, all supported by our expert scientists - please contact us to see how we may enhance your analytical capabilities or help solve your analysis problems.
Circular Dichroism (CD) spectroscopy is a powerful technique that is sensitive
to the chirality (handedness) of molecules. It provides a means of studying absolute stereochemistry,
enantiomeric composition, racemisation, enantio-discriminatory phenomena and molecular interactions.
Furthermore it is often the method of choice for studying the higher-order structure of
biomacromolecules such as proteins, glycoproteins and DNA; subtle changes in the folding and the
environment of chromophoric groups can be detected. The binding and association of achiral
species to chiral moeties (e.g. drug-protein or drug-DNA) can also be probed through their induced CD.
Optical Rotatory Dispersion & Polarimetry
ORD and polarimetry are techniques for determining the optical activity of chiral molecules. They have been largely superseded by CD spectroscopy, but remain of use for comparison with historical and legacy data. However, ORD is particularly useful for compounds that have little or no UV or visible absorbing chromophores, such as carbohydrates. Polarimetry, although subject to confounding solvent effects and issues with impurities, remains a common measure of optical purity of compounds.
Magnetic Circular Dichroism Spectroscopy
When a powerful magnetic field is applied to the sample, it can can generate additional circular dichroism signals from molecules, whether chiral or not. The technique can be diagnostic of transition metal ions and their complexation.
UV-Vis-NIR Absorption Spectroscopy
Absorption spectroscopy in the ultra-violet, visible and near infra-red wavelength regions provides a highly sensitive method of quantitatively characterising compound composition, stability, reactivity and interactions. It is often the method of choice for determining solubility, protonation/deprotonation (pKa), tautomerisms and complexation.
The detection of fluorescence from either specific molecular probes or the inherent fluorescence of molecules allows the investigation of the interactions and behaviour of molecules in solution, particularly using anisotropy polarisation and lifetime measurements. It can provide useful insights into the higher-order structure of proteins and can also be diagnostic of various impurities.
Fourier Transform Infrared Spectroscopy
FT-IR spectroscopy provides a fingerprint for the characterisation of the chemical structure of compounds in solution and the solid-state. It can also provide some information on the structure of proteins, glycoproteins and carbohydrates although Circular Dichroism is usually the method of choice for these applications.
Raman spectroscopy provides a fingerprint for the characterisation of the chemical structure of compounds in solution and the solid-state. It is particularly useful for characterising polymorph, solvates and other crystalline and amorphous forms.
Raman Optical Activity Spectroscopy
Raman optical activity (pioneered by our collaborator, Professor Laurence Barron, FRS) is a research technique that is sensitive to the chirality of molecules. It can be used to investigate the stereochemistry of small molecules and the folding and composition of biomacromolecules such as proteins, DNA, glycoproteins and carbohydrates etc. In combination with the pattern recognition techniques developed by Chiralabs, ROA spectroscopy is proving to be a powerful tool for the future.
High Performance Liquid Chromatography
HPLC, either on an analytical or preparative scale, provides a means of separating the components of a chemical mixture. Coupling with spectroscopic detection (e.g. LC-CD or LC-UV-Vis), electrochemical detection, or other detection (e.g. MS or RI) allows on-line characterisation of the components. The use of immobilised proteins as chromatographic phases aids the investigation of drug-proteins interactions.
X-ray Diffraction Crystallography
Single crystal X-ray diffraction is the primary technique for determining molecular structure at the atomic resolution, and allows characterisation of crystal structure, polymorphism, enantiomorphism and solvate formation. It is the primary standard for determining absolute stereochemistry.
Microscopic & Elemental Analysis
Scanning Electron Microscopy coupled to Energy Dispersive Spectroscopy (SEM-EDS) provides a powerful method of exploring the elemental composition of objects at the microscopic scale. In effect, an elemental analysis can be obtained for each each pixel in a microscopic image of an object, allowing detaled spatial maps of composition, impurities, contamination and faults.
Computational Chemistry & Molecular Modelling
Computational modelling of molecular structure and behaviour aids the interpretation of experimental results and the elucidation of molecular phenomena through hypothesis testing and prediction in silico.
Physical & Theoretical Chemistry
Data is interpreted with reference to physical and theoretical chemistry principles, including thermodynamics, kinetics, quantum theory and statistical mechanics in order to provide rational understanding of phenomena and their underlying causes and consequences.
Chemometrics & Pattern Recognition
A wide range of chemometric and pattern recognition techniques are employed to identify associations in data which may be used to classify, predict or rationalise differences, trends and similarities between samples, for example correlations between structure, composition, reactivity, stability, form, activity and toxicity.