US 4,283,626 A · Methods and apparatus for analysis of mixtures by mass spectrometry

Abstract

Apparatus for analyzing components in a mixture by the steps of introducing the mixture into the ion source of a mass spectrometer, ionizing some of the individual molecules representative of the mixture, using the mass spectrometer to select a beam of ions of a single ion mass which may be characteristic of a target compound in the mixture, passing the resultant single-mass beam of ions through a gas-filled collision chamber, and then, using a second mass spectrometer, determining the mass spectrum of the collision fragment ions to confirm the identity of the target compound, and by measuring the intensity of all or part of the mass spectrum, determine its concentration or amount in the original sample mixture. The same apparatus is suitable for fundamental measurements of the collision processes, which in addition to fragmentation include ion molecule reactions, charge changing collisions, and others, in addition to analytical applications. The collision region simultaneously provides collision gas confinement, primary and fragment ion confinement, variability of collision energy, and variability of drift field in the collision chamber. It is composed of a leaky dielectric material, in the form of a cylindrical tube joining the exit of the first quadrupole mass spectrometer to the entrance of the second mass spectrometer. Methods of data collection and handling are also disclosed.

Claims21

Dependent claims

A system of mass spectrometry for the analysis of ions of a selected mass produced by mass spectrometry wherein the ions are subjected to collision fragmentation and the resulting ion particles are subjected to further mass anaylsis, the system comprising:

an ion source for the sample molecules to be analyzed, a first quadrupole mass spectrometer adapted to receive ions from said source at its inlet and a second quadrupole mass spectrometer having its inlet proximate the outlet of said first mass spectrometer;
a collision chamber between said mass spectrometers, said collision chamber comprising shielding means composed of a leaky dielectric material which has the characteristics of an insulator for RF electrical fields and of an electrical conductor for electrical fields produced by DC and low scan frequency voltages utilized for quadrupole mass spectrometry;
and an ion detector adapted to receive ions from the outlet of said second quadrupole mass spectrometer.

A method for analyzing components in a mixture by mass spectroscopy wherein two quadrupole mass spectrometers are utilized which comprises the steps of:

ionizing at least part of said mixture to be analyzed;
mass scanning ions produced in the preceding step by a first quadrupole mass spectrometer and selecting from said scanning at least one ion mass characteristic of said mixture;
directing ions selected in the foregoing step at relatively low ion energies into a collision chamber which is located between said two quadrupole mass spectrometers, said collision chamber shielding said ions therein from the DC component produced by said quadrupole mass spectrometers and permitting the RF electrical fields to penetrate therein, a collision gas being introduced into said collision chamber whereby fragment and other ions produced as a result of collisions between said selected ions and said collision gas are produced;
mass scanning the fragment and other ions produced in the foregoing step for each ion mass selected in the earlier mass scanning step;
and mass scanning the ions selected in the foregoing step to produce a mass spectrum for comparison with known reference spectra whereby the components of said mixture are identified.

2 more elements

Dependencies are inferred from the claim text.

Methods and apparatus for analysis of mixtures by mass spectrometry

Life of this patent

Methods and apparatus for analysis of mixtures by mass spectrometry

Life of this patent

Abstract

Claims21