Quantitative determination of isoflurane enantiomers in blood samples during and after surgery via headspace gas chromatography–mass spectrometry

Salient Features of Enantioselective Gas Chromatography: The Enantiomeric Differentiation of Chiral Inhalation Anesthetics as a Representative Methodological Case in Point

“…This finding was subsequently confirmed in a small group of patients undergoing eye surgery (Fig. 17) [81]. The highest enantiomeric bias of 51.8% (+)-(S)-isoflurane (ee ¼ 3.6%) was observed after 1 day (1,440 min).…”

“…Upon anesthesia, approximately An enrichment of (+)-(S)-isoflurane was found in all blood samples drawn after anesthesia [82,83] in agreement with the former studies (Figs. 16 and 17) [80,81]. The highest level between 52% and 54% as opposed to 50% for the racemic form was reached on day 2 for most of the volunteers.…”

“…None of these factors had any significant influence on the shift toward accumulation of (+)-(S)-isoflurane, although in obese patients the preponderance of the (+)-(S)-enantiomer exceeded that in non-obese patients [83]. Quite unexpectedly, and due to the extraordinary sensitivity of the GC set-up, isoflurane enantiomers were already present in blood samples which were drawn pre-operatively before the actual onset of anesthesia as the result of the omnipresence of traces of isoflurane in the operating room and/or contamination of medical instrumentation with minute amounts of isoflurane [80,81]. The data obtained rely on the conditions that the distribution of the enantiomers in the headspace is not biased by the presence of enantiomeric constituents in the liquid (e.g., chiral proteins) and that the ionization of isoflurane enantiomers is not affected by the presence of co-eluted contaminants (e.g., acetone).…”

“…3, Fig. 9, right) [48] as an internal standard [80,81]. The method of enantiomer labeling requires two measurements on the enantioselective GC set-up (Fig.…”

Contributions to the theory and practice of the chromatographic separation of enantiomers

“…In the absence of self-recognition between enantiomers in nonracemic mixtures (the EE effect), 95 the enantiomeric ratio er is not obscured by work-up, sample manipulations, or detection. Quantitative determination of the inhalation anesthetic isoflurane in blood samples during and after surgery using the enantiomer labeling procedure employing (+)-(S )-isoflurane as internal standard has been performed by enantioselective headspace GC-MS. 96 …”