Liquid phase ion mobility spectrometry

A neutralization charge detection method for detecting ions under ambient and liquid-phase conditions

The neutralization charge detection method detects induction signals produced from the neutralization of electric charges of ions at metal surfaces. The signals are intense and can propagate through phase boundaries for detection. The detection method can detect ions under ambient and liquid-phase conditions with high sensitivity and fast response time.

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

Positively charged helium clusters, also called ‘snowballs’, have been investigated within normal liquid helium.

Ionization, transport, separation, and detection of ions in non-electrolyte containing liquids

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.