High-resolution and high-sensitivity UV-FAIMS based on optimization of separation time and transmission time

High-field asymmetric waveform ion mobility spectrometry (FAIMS) is a trace gas analysis technique with significant field application potential. Effectively enhancing resolution while maintaining high sensitivity remains the core challenge that urgently needs to be addressed for its further development. This study systematically investigated the effects of separation time and transmission time on the resolution and sensitivity of UV-FAIMS by modulating the separation region length and carrier gas flow rate. Experimental results revealed that: (1) Resolution exhibits a positive correlation with separation time but remains independent of transmission time; (2) Sensitivity exhibited dual dependence on both separation time and transmission time, showing enhancement with reduced time of both processes. Notably, sensitivity reached saturation when transmission time decreased beyond a critical threshold, suggesting the existence of an optimal transmission time under constant separation time to maximize sensitivity. Based on these findings, we propose a high-resolution and high-sensitivity detection method by optimizing separation time and transmission time. Compared to non-optimized configurations, this method achieved resolving power enhancements of 3.7- to 4.6-fold, while limiting sensitivity reductions to 46.2-59.9 %. Furthermore, the resolution improved by 5.9-fold, enabling effective separation of overlapping peaks in acetone-toluene mixtures. The limits of detection for acetone and toluene were reduced to 11.2 ppb and 6.1 ppb, respectively. This study introduced an innovative approach to enhance the resolution of UV-FAIMS that is as universally applicable as the optimization of the dispersion voltage, effectively mitigating the inherent trade-off between resolution and sensitivity of UV-FAIMS.