Abstract:
A novel atmospheric pressure ionization device (10) for the transport of charged particle produced at atmospheric pressure to a mass analyzer (24) includes a liquid shield (60) between the particle source (22) and the sample inlet (66) into the mass analyzer. The analyzer is located in a high vacuum region (20) and an intermediate low vacuum region (18) is provided between the sample inlet and the analyzer. An ion optical system includes electrostatic lens assemblies (80) in said vacuum regions for transporting charged particles from the inlet to the analyzer.
Abstract:
A mass spectrometry system arrangement includes a curved ion guide, where the curve of the ion guide is positioned such that a portion of the ion optics are visible from the ion guide entrance, e.g. line of sight or z-axis. There are four electrodes parallel with each other and the central curved axis. Each electrode is equally radially spaced from the curved central axis. For each cross section of the ion guide, the central curved axis being positioned at the origin, the curved electrodes being radially positioned at 45°, 135°, 225°, and 315°. Depending upon the system, a blocking device is positioned external to the ion guide but within the "line of sight" or positioned tangential to the rising section of the bent ion guide.
Abstract:
Sample material ionized in a sample receiving chamber is flowed into a sample conduit. Drying gas may also flow into the sample conduit and may be heated. The pressure and length of the sample conduit may be provided according to the product 50 or greater Torr-cm. The sample conduit may include a turn. The sample conduit may lead to an ion extraction chamber at which a sampling orifice may lead to a mass spectrometer. The diameter of the sample conduit may be larger than the diameter of the sampling orifice. An electrical field may be applied in the ion extraction chamber to slow incoming ions. A voltage jump may be applied to the sample conduit.
Abstract:
An apparatus and method for performing mass spectrometry uses an ion interface to provide the function of removing undesirable particulates from an ion stream from an atmospheric pressure ion source, such as an electrospray source or a MALDI source, before the ion stream enters a vacuum chamber containing the mass spectrometer. The ion interface includes an entrance cell with a bore that may be heated for desolvating charged droplets when the ion source is an electrospray source, and a particle discrimination cell with a bore disposed downstream of the bore of the entrance cell and before an aperture leading to the vacuum chamber. The particle discrimination cells creates gas dynamic and electric field conditions that enables separation of undesirable charged particulates from the ion stream.
Abstract:
Liquid from a liquid chromatograph or other sample source, preferably assisted by a high velocity coaxial gas jet, is sprayed through a capillary tube (40') producing a flow in a first direction of charged droplets (50'). A flow of heated gas (60), in a second direction different from the first direction, intersects the droplet flow at a region (64) upstream of an orifice (20'). The flows mix turbulently, with the second flow helping to evaporate the droplets to produce ions and helping to move the evaporating droplets toward the orifice (20'), providing a focusing effect. Ions are drawn through the orifice (20') into a mass analyzer and analyzed. Alternatively the flows of liquid and heating gas can be directed toward each other and at right angles to the axis through the orifice, and the inhaling effect of the orifice can be used to draw droplets toward it, or a third gas flow can be used for this purpose. The heated intersecting gas flow typically provides an increase in sensitivity (ion counts per second) of between 10 and 100 times. Heating the droplet plume also allows controlled desaturation of ions and an increase in the number of charges on them, without degrading the ions.
Abstract:
The invention provides a mass spectrometer having a quadrupole mass analyzer having an entrance aperture, an ion source disposed on the axis of said analyzer, particle intercepting means blocking the line-of-sight path between said ion source and said entrance aperture, and field generating means for directing ions from said source into said entrance aperture, said field generating means comprising first field generating means for deflecting ions from said source away from said axis to avoid said particle intercepting means and second field generating means for directing into said entrance ions so deflected by said first means. Using this arrangement, substantial improvement in signal:noise ratio is achieved, corresponding in some instances to a reduction in noise by a factor of over 100.