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Axen J.,Uppsala University | Malmstrom D.,Uppsala University | Axelsson B.-O.,Astra Zeneca R and D Lund | Petersson P.,Astra Zeneca R and D Lund | Sjoberg P.J.R.,Uppsala University
Rapid Communications in Mass Spectrometry | Year: 2010

Electrospray ionization performs best with volatile buffers. However, generally the best separation performance for capillary electrophoresis (CE) is achieved with non-volatile buffers. Hyphenation of CE with mass spectrometry (MS) utilizing atmospheric pressure photoionization (APPI) enables use of a wider range of separation buffers without compromising detection sensitivity. As APPI is considered to be mass flow sensitive, the use of a larger inner diameter separation capillary (75mm) allows larger volumes to be injected, without decreased separation performance, thus providing improved sensitivity (approx. a factor of 10), compared to the use of a 25 μm capillary. However, nebulizing gas flow and position of capillary tip in the sprayer have to be carefully optimized to prevent excessive band broadening. Further improvement in sensitivity (approx. a factor of 2) was obtained by decreasing the distance between the sprayer and ionization region, indicating that a specially designed CE/APPI-MS interface for low flow rates will be favourable. © 2010 John Wiley & Sons, Ltd.

Fredriksson M.J.,Mid Sweden University | Petersson P.,Astra Zeneca R and D Lund | Axelsson B.-O.,Astra Zeneca R and D Lund | Bylund D.,Mid Sweden University
Analytica Chimica Acta | Year: 2011

A strategy for rapid optimization of liquid chromatography column temperature and gradient shape is presented. The optimization as such is based on the well established retention and peak width models implemented in software like e.g. DryLab and LC simulator. The novel part of the strategy is a highly automated processing algorithm for detection and tracking of chromatographic peaks in noisy liquid chromatography-mass spectrometry (LC-MS) data. The strategy is presented and visualized by the optimization of the separation of two degradants present in ultraviolet (UV) exposed fluocinolone acetonide. It should be stressed, however, that it can be utilized for LC-MS analysis of any sample and application where several runs are conducted on the same sample. In the application presented, 30 components that were difficult or impossible to detect in the UV data could be automatically detected and tracked in the MS data by using the proposed strategy. The number of correctly tracked components was above 95%. Using the parameters from the reconstructed data sets to the model gave good agreement between predicted and observed retention times at optimal conditions. The area of the smallest tracked component was estimated to 0.08% compared to the main component, a level relevant for the characterization of impurities in the pharmaceutical industry. © 2011 Elsevier B.V.

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