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Deeside, United Kingdom

Powell M.,Quay Pharmaceuticals Ltd | D'Arcy M.B.,Quay Pharmaceuticals Ltd
Analytical Methods

The selectivity of different phenyl HPLC stationary phases has been evaluated with respect to structurally similar steroids, including sapogenins of plant origin. A column packing containing a biphenyl ligand was best at separating species that differed with respect to their degree of unsaturation. A diphenyl phase performed better than the biphenyl column in separating steroid epimers, but the best phase for epimer separation was octadecasilyl-bonded silica. The various mechanisms responsible for these results are discussed. © 2013 The Royal Society of Chemistry. Source

Powell M.,Quay Pharmaceuticals Ltd | Humphreys D.,Quay Pharmaceuticals Ltd | Nagle A.,Quay Pharmaceuticals Ltd | Polowy K.,SCYNEXIS | And 2 more authors.

An improved method for the assay of trifluoroacetic acid (TFA) in a cyclosporin-like drug substance is presented, based on ion chromatography with suppressed conductivity detection. Column fouling by the drug molecule is avoided by use of a sample preparation method in which the drug substance is precipitated at alkaline pH whilst the TFA remains in solution. The new method requires a smaller sample mass than a previous method based on headspace-GC-FID whilst achieving an improvement in sensitivity. During validation, the method's performance was found to be consistent with usual acceptance criteria, and the method was found to be robust in routine use. © 2011 Elsevier B.V. Source

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