Inverse Ion Mobility Spectrometry

Abstract

A novel method is proposed for enhancing the separation power of ion mobility spectrometry (IMS) and other similar pulsed techniques, such as time-of-flight mass spectrometry. In this technique, rather than generating an ion packet, a dip is created in the ion beam. This is achieved by an inverse pulse applied to the shutter grid. The dip moves with the same velocity as the ion packet, and the detector reads an inverse peak at the same drift time as that of the normal operation. Using this technique, we achieved 30-60% higher resolution compared to the normal method. In addition, two close peaks that were not resolved via normal IMS were well resolved to the baseline using this technique. The main reason for the increased resolution is likely the absence of space charge in the dip.

Perturbation-induced high-frequency pulsing of nano-ESI with facile ion selection at atmospheric pressure

“…The observed arrival curves resemble those in inverse ion mobility spectrometry where a continuous ion flux is disrupted by the gates, creating dips in ion intensity traces. 31 Importantly, the analyte-dependent appearance of 'dips' at +1375 V suggests differential ionization for the analytes. One possible explanation is the formation of multi-jets at higher voltages, 29 and a differential response of the jets to the field perturbation.…”

Determination of ochratoxin A in licorice root using inverse ion mobility spectrometry

“…The dip moved at the same velocity as the ion packet, and the detector read an inverse peak at a drift time similar to that of conventional linear mode of operation. This new technique, named inverse ion mobility spectrometry, was recently invented in our lab to enhance IMS resolution [30]. Except for the optimization, all the measurements including the calibration curve were obtained in the inverse mode.…”

“…The small OTA peak was surrounded by background peaks and, therefore, its integration proved difficult. It has been previously shown that resolution consider- ably increases in the inverse mode [30]. Hence, the technique was applied in order to better differentiate between the OTA peak and its busy surrounding.…”

“…The objective of the present study is to evaluate the performance of IMS in the determination of ochratoxin A in licorice roots. Measurements were carried out in the inverse operation mode to enhance the separation power of ion mobility spectrometry [30]. This novel method was developed in our lab in which, rather than generating an ion packet, a dip was created in the ion beam, hence increased resolution by up to 60% as compared to the conventional linear mode.…”

Resolution enhancement of overlapped peaks of ion mobility spectrometry based on stationary wavelet transform

“…Many effective techniques have been used to overcome this problem, which were classified into noncomputer and computer methods. The first method can be performed by changing the experimental and instrumental conditions including electric field, gate pulse width, temperature, pressure, drift tube length, drift gas, buffer gas modifier, high‐resolution IMS, and inverse IMS …”