Kratos Analytical Limited

Stephen C Davis

Sydney Evans

A mass spectrometry system comprises a source of ions for analysis, an ion storage device for separating the source ions as a function of their different mass-to-charge ratios, means for dissociating the separated source ions in order to generate daughter ions and an ion mirror for analyzing the daughter ions as a function of the mass-to-charge ratios. The mass spectrometry system has particular utility in the analysis of large molecules contained in biological and biochemical samples.

Mass spectrometry systems

An ion-storage device has an electrode structure for subjecting ions in a defined region along a path P to an electrostatic retarding field. The electrostatic retarding field is in the form of an electrostatic quadrupole field. Ions enter the defined region at a position P.sub.1 on the path and they exit the defined region at a position P.sub.2, having travelled a distance x.sub.T. Ions are subjected to the electrostatic retarding field during an initial part only of a preset time interval and the velocity of each ion during that part of the preset time interval is related linearly to its separation x from the exit position P.sub.2 by the expression, ##EQU1## where m is the mass of the ion, q is its charge and k is a constant. Ions having the same mass-to-charge ratio (m/q) all exit the field region at the same time during the remaining part of the preset time interval.

Ion storage device

An ion mirror for a time-of-flight mass spectrometer comprises a monopole electrode structure which operates at d.c. voltage. This electrode structure defines a field region in which an incident ion experiences an electrostatic reflecting force having a magnitude proportional to the separation of the ion from where it entered the field region or from where the ion exits the field region, if the latter separation is smaller. The ion occupies the field region for a time interval related to its mass but not its energy.

Growing community of inventors

Fen Ditton, United Kingdom

Stephen C Davis