Ionization, Transport, Separation, and Detection of Ions in Non-Electrolyte Containing Liquids

Abstract

Liquid phase ion mobility spectrometry (LPIMS) has the potential to be miniaturized such that it can be incorporated into chip based technology, providing higher performance in terms of both detection sensitivity and resolving power than is currently available by other separation technologies such as gas phase IMS, chromatography, or electrophoresis. This work presents modeling, simulation, and experimental investigations to characterize the mobility of ions in a liquid phase. This study included the ionization, transfer, separation, and detection of ions in non-electrolyte liquids. Using a resistive glass tube, mobility spectra were obtained by pulsed ionization for several different analytes, namely, tetramethylammonium chloride, tetrabutylammonium chloride, and dimethyl methylphosphonate (DMMP). Ion separation was demonstrated by separating solvent ions from the ions generated from the test compounds. Simulation and theoretical resolving power calculations were made to validate the experimental mobility measurements. A parametric study on the dependence of IMS resolving power on drift length, voltage across drift cell, and pulse width determined the requirements for designing a miniaturized IMS system, approximately the centimeter scale, with high performance, resolving power approaching 100 or higher. Mobility spectra are used for the first time to determine the diffusion coefficients of ions in a liquid.

Review on Ion Mobility Spectrometry. Part 2: hyphenated methods and effects of experimental parameters

“…[106][107][108][109][110][111][112][113] One method of comparing their efficiency is to use resolving power/length (R p /L). 114 Babis et al 106 obtained a R p /L of 3.2 cm −1 (for a length L of 4.65 cm and a R p of 15), although different in design Xu et al 112 obtained a R p /L of 3.4 cm −1 (for a length L of 3.50 cm and a R p of 12). As the length L of an IMS is reduced, the primary limitation to resolving power is the limit on producing effective ion pulses to inject into the IMS.…”

“…Nevertheless, several recent attempts have been made to miniaturize the IMS devices 106–113 . One method of comparing their efficiency is to use resolving power/length ( R p /L ) 114 . Babis et al .…”

Modelling the mobility of positive ion clusters in normal liquid helium over large pressure ranges

“…The investigation of ions in liquids is of considerable interest for the understanding of interactions in bulk liquids 1,2 as well as for applications, for examples ionic liquids [3][4][5] or chemical analysis. 6,7 Attractive interaction between ions and the solvent liquid gives rise to the formation of clusters whose size can be elucidated by measuring their mobility. The modelling of ion mobility is nevertheless a great challenge since fluid properties have to be taken into account.…”

A comparison of SIMION and LORENTZ for IMS simulation

“…Since the diffusion coefficient of ions decreases by three 20 [11,14,21], ions travel much more slowly in liquid than they do in gas. This opens the door to a smaller instrument that Fig.…”

“…The voltage across the drift region was 2580 V. Lamabadasuriya, et al, have reported preliminary experimental results with such a device [20]. We perform our analysis with an analyte of mass 167 u and K = 2.55 × 10 −3 cm 2 /Vs.…”