Ian Garrard

Bio: Ian Garrard is an academic researcher from Brunel University London. The author has contributed to research in topics: Countercurrent chromatography & Betanin. The author has an hindex of 18, co-authored 35 publications receiving 912 citations. Previous affiliations of Ian Garrard include University of West London.

Counter-current chromatography for the separation of terpenoids: a comprehensive review with respect to the solvent systems employed

Abstract: Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid–solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids—one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications.

Glucosinolates, structures and analysis in food

Abstract: Glucosinolates (GLS) are sulfur rich, anionic secondary metabolites found principally in the plant order Brassicales. This review focuses on identifying the range of GLS structures identified to date and summarises the current state of taxonomic reclassifications of GLS producing plants. Those Brassica species that are available to growers in the UK are highlighted and progress in the aspects of analytical chemistry relevant to conducting accurate determinations of GLS content of foods is reviewed. The degradation and derivatisation workflows that have been utilized for conducting “glucosinolate analysis” are summarized. A review is made of aspects of extraction, isolation, determination of purity, ultraviolet (UV) and mass spectrometry (MS) parameters, extinction coefficients, UV response factors, quantification procedures, and the availability of stable isotope labeled internal standards, and certified reference materials. An electronic database of structures, formulae and accurate masses of both the 200 known, and a further 180 predicted GLS, is provided for use in mass spectrometry.