@article{UrlaubKaiserScherf‐Claveletal.2021,
  author    = {Urlaub, Jonas and Kaiser, Reinhard P. and Scherf-Clavel, Oliver and Bolm, Carsten and Holzgrabe, Ulrike},
  title     = {Investigation of isomerization of dexibuprofen in a ball mill using chiral capillary electrophoresis},
  series = {Electrophoresis},
  volume    = {42},
  journal   = {Electrophoresis},
  number    = {17-18},
  doi       = {10.1002/elps.202000307},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225852},
  pages     = {1790 -- 1799},
  year      = {2021},
  abstract  = {Besides the racemate, the S-enantiomer of ibuprofen (Ibu) is used for the treatment of inflammation and pain. Since the configurational stability of S-Ibu in solid state is of interest, it was studied by means of ball milling experiments. For the evaluation of the enantiomeric composition, a chiral CE method was developed and validated according to the ICH guideline Q2(R1). The addition of Mg\(^{2+}\), Ca\(^{2+}\), or Zn\(^{2+}\) ions to the background electrolyte (BGE) was found to improve Ibu enantioresolution. Chiral separation of Ibu enantiomers was achieved on a 60.2 cm (50.0 cm effective length) x 75 μm fused-silica capillary using a background electrolyte (BGE) composed of 50 mM sodium acetate, 10 mM magnesium acetate tetrahydrate, and 35 mM heptakis-(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CD) as chiral selector. The quantification of R-Ibu in the mixture was performed using the normalization procedure. Linearity was evaluated in the range of 0.68-5.49\% R-Ibu (R\(^{2}\) = 0.999), recovery was found to range between 97 and 103\%, the RSD of intra- and interday precision below 2.5\%, and the limit of quantification for R- in S-Ibu was calculated to be 0.21\% (extrapolated) and 0.15\% (dilution of racemic ibuprofen), respectively. Isomerization of S-Ibu was observed under basic conditions by applying long milling times and high milling frequencies.},
  language  = {en}
}