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Improving the reproducibility in capillary electrophoresis by incorporating current drift in mobility and peak area calculations
Author(s) -
Petersen Nickolaj J.,
Hansen Steen H.
Publication year - 2012
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.201100551
Subject(s) - joule heating , capillary electrophoresis , capillary action , reproducibility , current (fluid) , chemistry , analyte , analytical chemistry (journal) , electromigration , voltage , mechanics , chromatography , materials science , thermodynamics , electrical engineering , physics , composite material , engineering
The traditional way of calculating mobility and peak areas in capillary electrophoresis does not take into account the changes in the buffer viscosity at different thermostatic control and that the analytes may accelerate during the individual runs due to Joule heating effects. We present a method for accounting for these changes based on the monitored changes in current during the separation. The calculation method requires measuring the initial resistance of the buffer filled capillary, performed using a 0.2 min voltage ramping at the start of a separation. The mobility calculation corrected for current drift allowed identification of the tested analytes independent from capillary dimensions, electric field strengths and temperature control. Furthermore, the peak areas become less influenced by the experimental conditions, since the velocities of the analytes passing the detector are corrected for the acceleration during the run. The short voltage ramping could be further used to evaluate the heat transfer of the capillary to the surroundings and to estimate the temperature changes during the separation. The temperature was shown to change the ionization of 2‐phenylethylamine in accordance to a p K a dependency of primary amines reported in literature.