Fourier transform ion mobility spectrometry with multinozzle emitter array electrospray ionization

Abstract

Fourier transform ion mobility spectrometry (FT-IMS) is a useful multiplexing method for improving the duty cycle (DC) of IMS from 1 to 25% when using an entrance and exit ion gate to modulate the ion current with a synchronized square wave chirp. To improve sensitivity further, this paper investigated the performance of FT-IMS using a frequency modulated single gate IMS system coupled to multi emitter array electrospray ionization. Signal to noise ratio, resolving power, linear range and limit of detection were evaluated using various tetra alkyl ammonium salts. The results demonstrated that a significant signal to noise ratio improvement of 4–6 times is achievable with the multi emitter array over that achieved with a single electrospray needle. The limits of detection for various tetraalkylammonium ions declined by 4 times on average and showed improved spectra quality compared to the signal averaging method. Multi emitter array electrospray ionization improved the ion intensities effectively, and Fourier transform IMS improved the duty cycle to 50% and hence improved the signal to noise ratio further.