Trapped and drift-tube ion-mobility spectrometry for the analysis of environmental contaminants: Comparability of collision cross-section values and resolving power.

Rationale: Ion-mobility (IM)-derived collision cross-section (CCS) values can serve as a valuable additional identification parameter within suspect and non-target screening studies of environmental contaminants. However, these applications require to assess the reproducibility of CCS calculations between different IM set-ups. Especially for the comparison of trapped and drift-tube IM (TIMS/DTIM) derived CCS values, data for environmental applications is lacking.

Methods: The presented study assessed the bias of TIMS derived CCS (CCS) values of 48 environmental contaminants from three classes in comparison to a previously established DTIM database. Based on two sets of isomeric bisphenols, the resolving power of both systems was compared, addressing the instrumental settings which influence the resolution of TIMS measurements.

Results: For 91% of the datapoints, bias between CCS and CCS values (latter set as reference) were < 2%, indicating a good inter-platform reproducibility. TIMS resolving power was dependent on the selected mobility window and ramping times whereby a resolution of up to 116 was achieved. Similar resolving power was observed for multiplexed DTIMS data if a high-resolution post-processing step was implemented.

Conclusions: These results provide valuable insights in CCS reproducibility facilitating database transfer in future TIMS based studies. Knowledge on the influence of acquisition settings on robustness of CCS calculations and resolving power can ease method development supporting efficient development and reliable identifications of emerging environmental contaminants.