Highly complex samples associated with mass spectrometry are typically separated prior to characterization based upon mass in the mass spectrometer. Although liquid and gas chromatography are the most widely use separation methods, ion mobility spectrometry (IMS) is also being more widely used. However, the power of a given IMS device to separate two components of a mixture for effective analysis is limited by the fact that ionic species diffuse with time, thus creating overlaps in the separation results.

PNNL’s ion compression device solves this problem by causing ions with similar mobilities to bunch together. The device dynamically subjects ions to a non-constant electric field under low pressure to form a potential gradient along a portion of the IMS through which the ions drift. The potential gradient is between 0 and about 5,000 volts/mm, progressively increasing or decreasing along the length of the IMS. Total ion drift time ranges from about 0 to about 60 seconds. Because each ion mobility packet bunches together, the results generated by the IMS show sharper peaks that can be more easily matched to specific analytes.

The ion compression device can be used to improve the results of ion mobility separations for a variety of ionization approaches, including photoionization, Corona discharge, laser ionization, electron impact, field ionization, chemical ionization, and electrospray ionization, making it highly versatile.