Collision Cell

摘要

A method of operating a gas-filled collision cell in a mass spectrometer is provided. The collision cell has a longitudinal axis. Ions are caused to enter the collision cell. A trapping field is generated within the collision cell so as to trap the ions within a trapping volume of the collision cell, the trapping volume being defined by the trapping field and extending along the longitudinal axis. Trapped ions are processed in the collision cell and a DC potential gradient is provided, using an electrode arrangement, resulting in a non-zero electric field at all points along the axial length of the trapping volume so as to cause processed ions to exit the collision cell. The electric field along the axial length of the trapping volume has a standard deviation that is no greater than its mean value.

主权项

1. A method of operating a gas-filled collision cell in a mass spectrometer, the collision cell having a longitudinal axis, the method comprising:
causing ions to enter the collision cell through an ion entrance of the collision cell in a forward direction; generating a trapping field within the collision cell so as to trap the ions within a trapping volume of the collision cell, the trapping volume being defined by the trapping field and extending along the longitudinal axis; processing trapped ions in the collision cell; and switching between two modes of providing a DC potential gradient, using an electrode arrangement, the DC potential gradient in both modes resulting in a non-zero electric field at all points along the axial length of the trapping volume so as to cause processed ions to exit the collision cell, wherein and the electric field along the axial length of the trapping volume has a standard deviation that is no greater than its mean value; and wherein the DC potential gradient in the first mode causes processed ions to exit the collision cell in the forward direction and the DC potential gradient in the second mode causes processed ions to exit the collision cell in a reverse direction generally opposed to the forward direction.