Abstract: The invention relates to a mass spectrometer comprising a laser system for mass-spectrometric analyses with ionization of analyte molecules in a sample by matrix-assisted laser desorption. A mass spectrometer with a pulsed UV laser system produces a spatially distributed spot pattern with peaks of uniform energy density on the sample, increasing thereby the degree of ionization for analyte ions as compared to conventional spot patterns. The spot pattern with peaks of uniform energy density can be produced by homogeneous illumination of a pattern generator, for example a lens array. The homogeneous illumination can be generated by a low-cost beam-shaping element, which does not act on the UV beam but on the original infrared beam, in conjunction with changes to the beam cross-section and beam profile brought about by the nonlinear conversion crystals.

Abstract: A complex protein mixture is analyzed by jointly digesting the mixture, separating the digest peptides chromatographically or electrophoretically, and ionizing the digest peptides eluting from the separation device by an ionizing method that generates multiply charged ions. Digest peptide ions within a pre-selected range of m/z-values are isolated in an RF ion trap and subsequently reduced in their charge state. The charge-reduced ions can be measured with very high sensitivity. By repeating this process with adjacent isolation mass windows within the time duration of each separation peak, it is possible to determine the masses m, the prevalent charge states z, the retention times t, and the intensities i of a huge number of digest peptides of the complex protein mixture in a single separation run.

Abstract: An ion cell having an axis includes a sheath of individual electrodes that extends along the axis and defines an internal volume. Adjacent individual electrodes are electrically insulated from each other. The individual electrodes each receive a DC potential and RF voltage. At least some of the individual electrodes have a width that varies in the axial direction such that an electrical effect on an axis potential varies along the axis of the ion cell.

Abstract: The invention relates to devices and methods for the storage of ions in mass spectrometers. The invention proposes the generation and superposition of two multipole fields of different order, independent of each other, in an RF multipole rod system. In an embodiment with eight pole rods, for example, it is thus possible to jointly store low-energy electrons in a central RF quadrupole field, which effectively acts only on electrons and holds them together radially, on the one hand, and multiply charged heavy positive ions in an RF octopole field, which effectively acts only on the ions, on the other hand, in order to fragment the positive ions by electron capture dissociation (ECD).

Abstract: In a Kingdon ion trap in which harmonic ion oscillation in a potential well in a longitudinal direction is completely decoupled from ion oscillation in a direction transverse to the longitudinal direction, ions enter the trap via an entrance tube extending through, but electrically insulated from, one of the Kingdon trap housing electrodes and located outside the minimum of the potential well in the longitudinal direction. The geometry of the Kingdon trap is arranged so that the oscillating ions introduced through the entrance tube cannot return to the entrance tube until they have performed several longitudinal oscillations during which time heavy ions can be introduced into the trap.

Abstract: Ions are introduced into a Kingdon ion trap in which the ions can oscillate harmonically in a potential well in the longitudinal direction, essentially decoupled from their transverse motion by a Kingdon ion guide, which can consist of a drill-hole through the wall of the ion trap housing electrodes and a central wire. An injection potential is first applied to the wire, but once the heaviest ions of interest have been injected into the trap, the potential of the wire is switched to the potential of the housing electrodes, to trap the ions in the trap. The ions introduced into the Kingdon ion trap may come from a small ion cloud, located in a Paul trap.

Abstract: Charged spray droplets are guided in a pseudopotential distribution generated by audio frequency voltages at electrodes of a guiding device, focusing the spray droplets toward the axis. An axial electric field profile and an axial flow profile of a drying gas in the guiding device allow the drift of different-sized droplets to be controlled in the longitudinal direction of the guiding device, so that the droplets are roughly equal in size when they leave the guiding device and finally dry up shortly after leaving. As a result, the ions are formed in a relatively small spatial region. Electrostatic potentials guide the analyte ions from this small spatial region to the entrance aperture of the inlet capillary; during this process, very light ions, especially protons and water-proton complexes, can be filtered out by a mobility filter.

Abstract: A method for determining the concentration ratio in a sample of a target peptide to a reference peptide that is chemically identical with the target peptide, but labeled by isotopes, acquires mass spectra of the target and reference peptides. One of a plurality of families of superimposed bell-shaped curves which is a best fit to ion current peak groups of the target and reference peptides in the mass spectra is determined by varying parameters of the families. In each family, each bell-shaped curve has a predetermined height, the curves have fixed distances from each other and the relative curve heights and curve distances in the families are individually calculated from an elemental composition of the peptides and an isotope abundance distribution of elements composing the peptides, taking into account purity of the isotopes. The concentration ratio is then determined from the parameters of the best fit.

Abstract: In an RF quadrupole ion trap having electrodes to which RF voltages are applied, ions having m/z ratios outside of a predefined narrow range of charge-related masses m/z are removed from the trap by applying a DC voltage pulse to at least one of the trap electrodes to remove from the trap the ions with high values of charge-related masses. The DC voltage pulse is preferably applied in combination with a variation of the RF voltage amplitudes to simultaneously remove from the trap ions of low charge-related masses. The DC and RF voltage amplitudes are changed in such a manner that any excitation of ions having charge-related masses within the predefined range by frequency mixtures is avoided.

Abstract: The invention relates to measuring devices of an electrostatic Fourier transform mass spectrometer and measurement methods for the acquisition of mass spectra with high mass resolution. The measuring device includes electrostatic measuring cells according to the Kingdon principle, in which ions can, when appropriate voltages are applied, orbit on circular trajectories around the cylinder axis between two concentric cylindrical surfaces, which are composed of specially shaped sheath electrodes, insulated from each other by parabolic gaps, and can harmonically oscillate in the axial direction, independently of their orbiting motion. In the longitudinal direction, the two cylindrical surfaces of the measuring cell are divided by the parabolic separating gaps into different types of double-angled and tetragonal sheath electrode segments.

Abstract: The invention relates to a linear multipole ion storage device which is suitable for reactions between positive and negative ions, and for fragmentation reactions by electron transfer dissociation (ETD) in particular. The invention uses a linear RF ion trap with at least three pairs of rods with a new type of electronic power supply. The two phases of a first RF voltage are applied to the pole rods alternately around the circumference and confine positive as well as negative ions in the radial direction. A second RF voltage is either applied single-phase to some of the pole rods, but not to all of them, or two-phase to unequal numbers of pole rods so that the axis potential oscillates with the frequency of this second RF voltage and generates a pseudopotential barrier which acts axially on ions of both polarities at the ends of the ion storage device. In the interior, the second RF produces a complex superposition field resulting in an increased fragmentation yield for ETD.

Abstract: Ions with a predetermined ion mobility range are produced by filtering ions entrained in a stream of moving gas with two ion mobility low pass filters located consecutively in the gas stream. Each filter is formed by applying a DC electric field to the gas stream which causes the ions to move in a direction opposite to the gas flow. Ions are collected between the two filters and transferred to a detector or analyzing device. In one embodiment, the maximum field strength of the electric field barrier in the first ion mobility low pass filter is continued as a plateau of essentially constant field strength up to the electric field barrier in the second ion mobility low pass filter, which has a maximum field strength higher that the maximum field strength of the electric field barrier in the first ion mobility low pass filter.

Abstract: A method and apparatus for transmitting ions in a mass spectrometer from an ion source to a mass analyzer extracts analyte ions from the ion source in such a manner that the number of extracted analyte ions is maximized. The ions are then transmitted through an ion guide to the mass analyzer. The ion guide is filled with an interaction gas and its operating parameters are adjusted so that, as the ions pass through the ion guide, the analyte ion energy distribution width is narrowed and the analyte ions are collimated within the ion guide to improve the resolution and sensitivity of the mass analyzer.

Abstract: The invention relates to measuring the mobility spectra of ions with ion mobility spectrometers (IMS). The invention provides an analog modulation of the ion current of an IMS ion source with a continuous modulation function, the instantaneous frequency of which temporally varies across a large frequency range, and a generation of the mobility spectrum from the measured ion current by a correlation analysis with the modulation pattern. The modulation can, for example, be produced by the gating grid, which is usually present. The analog modulation removes many of the difficulties which occur with square-wave modulation and leads to a surprisingly stable evaluation which is relatively insensitive to noisy signals and produces a high mobility resolution at very low noise.

Abstract: Ions with a predetermined range of ion mobilities are produced by filtering input ions with at least two consecutive ion mobility high pass and/or low pass filters. Each ion mobility filter is formed by entraining ions in a moving gas and applying a DC electric field to the ions which causes the ions to move in a direction opposite to the gas flow. An ion mobility high pass filter is formed when the DC electric field drives the ions against the flow of gas, whereas an ion mobility low pass filter is formed when a the gas flow drives entrained ions against an DC electric field barrier.

Abstract: In an ion mobility spectrometer in which a gas pushes ions along a spectrometer axis against and over an electrical field barrier, the electric field barrier is generated with a plateau of slightly increasing height along the axis of the spectrometer. Alternately, the electric filed barrier may have a plateau with constant height, but the gas flow decreases in velocity along the axis of the spectrometer in the vicinity of the plateau.

Abstract: In an ion mobility spectrometer in which a gas flows through a gas-tight tube with a radially quadrupolar RF field therein and blows ions against a DC electric field barrier, a mobility scan with a mobility scale that is linear in time is obtained by holding the height of the DC electric field barrier constant while changing the pressure and temperature conditions of the flowing gas. Alternatively, the mobility scan is performed by holding the pressure and temperature conditions of the flowing gas constant and reducing the height of the DC electric field barrier non-linearly with respect to time.

Abstract: The invention relates to the measurement of daughter ion spectra of analyte substances that are ionized by means of matrix-assisted laser desorption. The invention shows how to record several daughter ion spectra from several parent ions per single pulse of laser light, that is per desorption event, by spatially splitting the ion beams or by temporally sequencing the spectral measurement; the various parent ions are selected one after another by switching the parent ion selector several times. Summing up corresponding individual daughter ion spectra from many pulses of laser light leads to several sum spectra being recorded practically synchronously with the same series of laser light pulses, with correspondingly reduced sample consumption and shortened data acquisition time.

Abstract: Microorganisms, particularly bacteria, are identified and characterized on the basis of a mass spectrometric measurement of their protein profiles with ionization by matrix-assisted laser desorption. In order to measure the microbial resistance to antibiotics, the protein profiles of microorganisms are measured after cultivation for a short time duration in nutrient media containing the antibiotics.

Abstract: Microorganisms, particularly bacteria, are identified and characterized on the basis of a mass spectrometric measurement of their protein profiles with ionization by matrix-assisted laser desorption. In order to measure the microbial resistance to antibiotics, the protein profiles of microorganisms are measured after cultivation for a short time duration in nutrient media containing the antibiotics.