Terbutaline enantiomer separation and quantification by complexation and field asymmetric ion mobility spectrometry-tandem mass spectrometry

Recently, we introduced a new approach to chiral separation and analysis of amino acids by chiral complexation and electrospray high-field asymmetric waveform ion mobility spectrometry coupled to mass spectrometry (ESI-FAIMS-MS). In the present work, we extended this approach to the separation of the drug compound terbutaline. Terbutaline enantiomers were complexed with metal ions and an amino acid to form diastereomeric complexes of the type [M(II)(L-Ref)2((+)/(-)-A)-H](+), where M(II) is a divalent metal ion, L-Ref is an amino acid in its L-form, and A is the terbutaline analyte. When metal and reference compound were suitably chosen, these complexes were separable by FAIMS. We also detected and characterized larger clusters that were transmitted at distinct FAIMS compensation voltages (CV), disturbing data analysis by disintegrating after the FAIMS separation and forming complexes of the same composition [M(II)(L-Ref)2((+)/(-)-A)-H](+), thus giving rise to additional peaks in the FAIMS CV spectra. This undesired phenomenon could be largely avoided by adjusting the mass spectrometer skimmer voltages in such a way that said larger clusters remained intact. In the quantitative part of the present work, we achieved a limit of detection of 0.10% (-)-terbutaline in a sample of (+)-terbutaline. The limit of detection and analysis time per sample compared favorably to literature values for chiral terbutaline separation by HPLC and CE.