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Novel chromatographic approaches for class separations of small molecules
Dissertation   Open access

Novel chromatographic approaches for class separations of small molecules

Adam Joseph Socia
Doctor of Philosophy (Ph.D.), Drexel University
May 2016
DOI:
https://doi.org/10.17918/etd-7210
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Abstract

Hydrophilic interaction liquid chromatography Chemistry, Analytic Chemistry Amino Acids Liquid Chromatography
Chromatographic separations have been a part of the analytical scientists' toolkit for over a century and the techniques are constantly being improved upon. As chromatography progresses, more difficult separations become possible, and eventually commonplace. Advances in stationary phase technology, such as superficially porous particles, and the rapid growth of hydrophilic interaction liquid chromatography, have opened the doorway to the exploration of novel separations. The development of analytical methods for the sensitive and quantitative analysis and separation of underivatized amino acids is an example of a very challenging class of small molecules to separate. Here we detail the development, validation and application of the successful separation of these underivatized amino acids. With the advancement of stationary phases that are more resistant to pH than their predecessors were, analyses using wide-ranging pH values can now be explored without damaging the column components. Careful design and application of pH gradients using these columns can therefore be used to not just to separate analytes from each other, but also to sequentially separate by the analyte classes, such as acidic, basic and neutral components. This novel technique developed here is termed sequential elution liquid chromatography. This simplification of the chromatogram by class separation via use of multiple segments within a single analysis allows for a reduction of the amount of peaks that need to be separated, thereby increasing the probability of the successful separation. A set of benzene derivatives was used here to demonstrate the potential of this novel technique and is contrasted to traditional reverse phase separations.

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