How to Improve the Resolving Power of Compact Electrospray Ionization Ion Mobility Spectrometers

Coated Blade Spray Ion Mobility Spectrometry

Coated blade spray (CBS) is a microextraction technology with blades that serve as both the extraction device and the electrospray ionization (ESI) emitter. CBS is designed for easy and rapid extraction of analytes in complex matrices as well as ESI directly from the blade. The technology selectively enriches the components of interest on a coated metal blade. The coating consists of a selective polymer. So far, CBS has only been coupled with mass spectrometry but never with ion mobility spectrometry (IMS), where ions are separated and detected based on their ion mobility in a drift gas under the influence of an electric field, while instrumentation is compact and easy to operate so that the advantages of CBS can be particularly well exploited. Therefore, this work focuses on coupling CBS with our previously described ESI-IMS. The ion mobility spectrometer has a drift length of only 75 mm and provides a high resolving power of RP = 100. In this work, preliminary measurements of CBS-IMS are presented. In particular, the detection of benzodiazepines and ketamine in drinks and the pesticide isoproturon in water samples is shown to demonstrate the feasibility of CBS-IMS.

Evaluation of Fourier deconvolution ion mobility spectrometer as high-performance gas chromatography detector for the analysis of plant extract flavors

The Fourier deconvolution ion mobility spectrometer (FDIMS) offers multiplexing and improves the resolving power and signal-to-noise ratio. To evaluate the FDIMS as a detector for gas chromatography for the analysis of complex samples, we connected a drift tube ion mobility spectrometer to a commercial gas chromatograph and compared the performance including resolving power, sensitivity, and linear range using 2,6-di‑tert-butylpyridine. Mixed standards were also injected into the tandem system to evaluate the performance under optimized conditions. A complex plant extract sample used as natural flavoring was investigated using the resulting system. The results show that the instrument implemented with the Fourier deconvolution multiplexing method demonstrated higher performance over the traditional signal averaging method including higher resolving power, better limit of detection, and wider linear range for a variety of compounds and natural plant extract flavorings.

Electrospray Ion Mobility Spectrometer Based on Flexible Printed-Circuit Board Electrodes with Improved Resolving Power

An easily built drift tube instrument with ring electrodes made of rolled-up flexible printed circuit boards is reported. Its resolving power was maximized by careful attention to the drift tube geometry and the response time of the detector amplifier and by employing a high separation field strength. The separation of singly charged aliphatic quaternary ammonium ions introduced by electrospray was performed, and the measured resolving power was between 86 and 97% of the theoretical limit for three different drift tube lengths investigated. For the longest drift length of 30 cm, a resolving power of up to 228 was obtained. Three benzalkonium chlorides were also separated with resolving powers of over 210. The tristate injection scheme can also be used, with only a small loss of the separation performance compared to the two-state injection.