Abstract: A method relates to exact mass determination of analyte ions in time-of-flight mass spectrometers using an ionization of analyte substances on sample supports by matrix-assisted laser desorption (MALDI), and an improvement in mass resolution by time-delayed ion acceleration in the field between the sample support and an intermediate acceleration electrode. It particularly relates to methods for the stabilization of a once calibrated mass scale when there are unwanted changes in the distance of the sample support from the intermediate acceleration electrode.An unknown change of this distance can be compensated for by a coupled change of both total accelerating voltage and partial acceleration voltage between sample support and intermediate electrode in a simple manner by adjusting the time of flight of ions from a reference substance to the value given by the calibrated mass scale. Oligomeric ions from the matrix of the MALDI method serve very well as reference ions.

Abstract: The invention relates to virtual impactors with slit-shaped nozzles. Virtual impactors serve to enrich aerosol particles of certain magnitudes from gases, particularly from ambient air, for the purpose of examining these particles. For very strong enrichments, reaching up to many hundreds of times the initial concentration, very effective multi-stage virtual impactors with hundreds of nozzles have been developed. However, these are difficult to manufacture and to clean. The individual nozzles can be replaced by slits which are easier to manufacture. With slit-shaped nozzles problems with instability at the ends of the slits occur. The invention describes slit-shaped nozzles, the slits of which have no ends because they are designed as curved, closed figures. By contrast with the prior art which relates to circular slits in parallel plates, here any closed figures are represented, including ones which are not in plane-parallel plates.

Abstract: The invention relates to an RF quadrupole ion trap mass spectrometer with ionization of the substance molecules outside the vacuum system.The invention consists of using only a single high-vacuum pump for generating the vacuum without any differential pump stages and generating the necessary pressure stages for operating the mass spectrometer by means of a sequence of openings with adjusted conductances. The necessarily very small inlet opening to the vacuum system is only able to transport very small quantities of ions of the analyzed substances in the gas stream. However, these quantities are adequate for operating the mass spectrometer because the ion trap used as mass spectrometer is capable of collecting and storing ions over relatively long periods of time.

Abstract: A system and a method for the introduction of sample supports, which hold large numbers of analysis samples, into the ion source region of a mass spectrometer. The sample supports are especially intended for the ionization method using matrix-assisted desorption through laser bombardment (MALDI). The system consists of using an evacuable, sealable and removable cassette which, instead of using a through-passage lock chamber with two lock valves, can be attached in a simple manner to the entrance opening for the ion source of the mass spectrometer. Only the entrance opening has a lock valve, and the expensive second lock valve in the lock chamber is no longer needed. The cassette can also be used for protected transport and for storage of the sample supports, and in particular for storage of the samples under protective gas or vacuum.

Abstract: A method for matrix-assisted ionizing laser desorption of large analyte molecules (MALDI) in a vacuum for the generation of ions for mass spectrometric investigation of the analyte substance is provided. The matrix substance for matrix-assisted ionizing laser desorption is formed from at least two different components. One of the components is very adsorptive, as well as being decomposable thermolytically into small fractions. Additional matrix components are selected for protonation of the analyte molecules. In particular, a thin layer of nitrocellulose (also called cellulose nitrate) with a protonating substance embedded within it is particularly suitable. This layer, which is insoluble in water, adsorbs large analyte molecules from an aqueous solution at its surface.

Abstract: Curved rf multipole ion guides or angled linear rf multipole ion guides are designed to be rotatable or shiftable. Thus, the direction of guided ions can be altered by rotating or shifting these ion guides. In a mass spectrometer equipped with a multitude of ion sources, this allows to switch between ion sources without venting the vacuum system.

Abstract: An ion trap consists of separating the ions into ion packages within an electrical travelling wave field operated at the frequency of the drive voltage for the ion trap, or at an integral fraction of the same, transporting the ion packages by the travelling wave field to the ion trap, and injecting the ion packages into the ion trap with a favorably selected velocity and at the correct point in time. A slowing-down path at the end of the travelling field allows ions of a greater mass to be injected somewhat earlier than light ions, whereby the simultaneous capture of ions of different masses becomes more favorable.

Abstract: The invention relates to methods and devices for the temporary storage of ions which are to be subjected to mass spectrometric analysis. Such temporary storage of ions in an RF multipole rod system for their analysis in an RF quadrupole ion trap is known from U.S. Pat. No. 5,179,278.The invention uses this known temporary storage for such ions which are produced in an ion source from substance peaks from chromatographic or electrophoretich separation devices, or from other devices which feed substances in form of short-lasting peaks. The temporary store thereby accepts sufficient ions of a substance peak for several successive mass spectrometric analyses, so that a mass spectrometric characterization of the substances, which may also require varying measurement methods, is made possible to the desired degree.

Abstract: The invention relates to methods and devices for the orthogonal injection of ions into a time-of-flight mass spectrometer, whereby the ions preferably originate from ion sources which are located outside of the vacuum system of the mass spectrometer. The invention consists of first introducing the ions into a multipole rod arrangement with extended pole rods which stretches orthogonally to the flight direction of the ions in the time-of-flight spectrometer, and then outpulsing the ions by means of a rapid change of the electrical field, perpendicular to the rod direction, through the intermediate space between two rods. The multipole arrangement can take the form of an ion storage device by fitting reflectors to the ends. The multipole arrangement can be filled with the aid of another multipole arrangement which takes the form of an ion guide.

Abstract: The invention relates to methods and devices for the efficient threading in of ions, which have been generated in a gas volume, into the suctioning air stream of an aperture, the diameter of which is small in comparison to the extent of the gas volume. The aperture can be an introductory aperture for ions into the vacuum system of a mass spectrometer, or however the end aperture of a capillary which transfers ions into the vacuum of the mass spectrometer. The invention consists of an electrical drawing field for generating the ions, the lines of force of which point to the edge of the aperture or into the aperture itself and allow the ions, directed by the field, to migrate through the ambient gas to the aperture. The field-guided migration of the ions through the gas is known as "ion mobility". Near the aperture, the ions are caught by the suctioning gas stream and entrained into the aperture by viscous friction.

Abstract: The invention relates to the use of a time-of-flight mass spectrometer to analyze substance molecules which are ionized by laser desorption, particularly by matrix-assisted laser desorption (MALDI). In detail it relates to the process for improving mass resolution by the known method of delayed acceleration (sometimes called delayed extraction) of the ions, and devices for the performance of this method. The invention consists of using an optical device with gridless apertures for the acceleration of the ions and refocusing the ion beam divergence due to the lens effect of the apertures, by means of a lens arrangement in the drift region of the time-of-flight spectrometer. For laser light pulses, illumination, and observation, there are further lateral holes in the electrodes of the optical device.

Abstract: The invention relates to methods and devices for the effective introduction of ions, which are stored in an RF ion guide into a quadrupole ion trap.The invention consists of arranging a switchable ion lens between the RF ion guide and the quadrupole ion trap, and introducing the ions into the quadrupole ion trap by a suitable connection of the ion lens only during the filling period, while otherwise the ions are reflected back into the RF ion guide. The filling period can be divided up and limited to the capture intervals of the quadrupole ion trap during each RF period. Measurement of the filling rate can be made by switching open the ion lens longer then the admission interval of the quadrupole ion trap, and measuring the flow of the ions passing through on the detector.

Abstract: In a time-of-flight mass spectrometer with an ion reflector located after the ion source and before the ion detector, to compensate for different starting energies of ions of equal masses, in the ion flight path inside or after the ion reflector at least one electrode is provided for, to which a pulsed high voltage is applied in such a way that within a predetermined narrow range of ion masses, time-of-flight errors for ions of equal masses due to different formation locations or times in the ion source are compensated for at the ion detector. In this way, apart from an energy compensation, also time-of-flight errors of the ions under investigation can simultaneously be compensated for.

Abstract: The invention relates to methods and devices for transporting ions in a laminar gas flow through a tube, preferably through a capillary tube. During the transport, the ions must not touch the wall of the capillary or else they will be discharged upon collision with the wall. The invention consists of keeping the ions in the gas flow free of any wall collisions by gas-dynamic focussing of the ions into the center of the gas stream. Focussing is achieved when the ions are decelerated by an electric field relative to the gas flow so that they have a lower transport velocity than the gas stream. Due to the parabolic velocity profile of the laminar gas stream, ions which are not at the center of the capillary are subjected to circumference by gas with different velocities at both sides, resulting in a force toward the capillary axis. This component of force is the stronger the farther the ions are away from the center axis and the more they are decelerated.

Abstract: The invention relates to methods for the structural analysis of large substance molecules, preferably of chain molecules such as peptides for example, by scanning daughter or fragment ion mass spectra in time-of-flight mass spectrometers with reflectors. The invention consists in the differentiation between daughter ions from spontaneous fragmentations of ions by high-energy collisions and those from delayed fragmentations of metastable ions, by separately detecting the different kinds of ions using a special electrostatic energy filtration by a short Einzel lens directly behind the collision zone. Spontaneously decomposing ions leave the fragmentation zone with smaller kinetic energy due to the loss of mass. Daughter ions from spontaneous decompositions on the one hand, and from metastable decompositions on the other, display characteristic differences which can be used for the determination of structure.

Abstract: A method of mass selective loading of ion traps by ejection of undesirable ion species during the loading process by applying RF voltages with a mixture of frequency components to the trap electrodes. For several mass spectrometric investigations only ions with desired mass-to-charge ratios are to be loaded into the ion trap in order to achieve a more efficient utilization of the limited storage capability of the ion trap. The generation rate of the ions during the loading process in such a way that the equilibrium of the space charge inside the ion trap, balanced between ion generation rate and ion ejection rate, does not significantly deteriorate the mass resolution of the ejection process.

Abstract: The invention relates to methods and devices for the efficient and loss-free transfer of ions in moderate vacuum from a first location (a source) to a second location (a user).The invention consists of an arrangement, reaching from the first location to the second, of five pole rods (a pentapole) to which a five-phase radio frequency (RF) voltage is applied.

Abstract: The invention relates to a device and method for the ionization of non-vaporizable substance molecules at atmospheric pressure by chemical ionization (APCI=atmospheric pressure chemical ionization). The invention consists of desorbing the analyte substances which are mixed with decomposable substances (matrix substances) in solid form on a solid support, by laser irradiation at atmospheric pressure into a gas stream, and to add sufficient ions for proton transfer reactions to the gas stream. Explosives like cellulosis trinitrate or trinitro toluene (TNT) form a preferred class of decomposable matrix substances.

Abstract: A method for the high resolution analysis of analyte ions in a time-of-flight mass spectrometer. The method consists of the generation of an intermediate time-focus plane for ions of a certain mass at a location between an ion source and an ion reflector, and then using the ion reflector to temporally focus the ions of equal mass and differing velocities which pass this plane at the same time onto a detector. For time-of-flight mass spectrometers with an ion selector, the ion selector is particularly favorable location for this intermediate plane with time focus; and with a collision cell for the collision fragmentation of the ions, the collision cell is a particularly favorable location.

Abstract: A method for the simultaneous resonant excitation of the oscillations of ions of various mass-to-charge ratios in ion traps, particularly for the ejection of undesirable ion species, by applying RF frequencies with various frequency components to electrodes of the ion trap. The method consists in generating and storing a broadband signal for as short a time as possible so that it can be fed to the ion trap a number of times in succession cyclically, without generating undesirable interference due to phase shifts. The excitation of the ions should be as temporally constant as possible throughout the waveform period. The duration of the waveform period depends on the mass resolution required. Excitation is terminated by controlling the broadband signal gradually toward zero in a constant function.