Bruker Daltonik Gmbh

Bruker-Franzen Analytik Gmbh

Other

Michael Schubert

Jochen Franzen

Melvin Andrew Park

Armin Holle

Gerhard Weiss

Andreas Brekenfeld

Karsten Michelmann

Carsten Stoermer

John Christian Fjeldsted

Alfred Kraffert

Mel Park

The invention relates to the operation of trapping ion mobility spectrometers based on pushing ions by a gas flow against a counter-acting electric DC field barrier, preferably in combination with a mass analyzer as ion detector. The invention provides an additional RF ion trap upstream of the trapping ion mobility spectrometer, wherein the RF ion trap is operated as an accumulation unit in parallel with the trapping ion mobility spectrometer such that a first group of ions can be analyzed in the trapping ion mobility spectrometer while a second group of ions from an ion source are simultaneously collected in accumulation unit.

Trapping ion mobility spectrometer with parallel accumulation

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.

Mixed radio frequency multipole rod system as ion reactor

In a three-dimensional Paul RF ion trap the ring electrode and end cap electrodes are formed from pairs of pole rods. This multipole rod system is then operated as a linear ion trap with a constant field distribution along the multipole rod system. While the system is operating as a linear ion trap, analyte ions are introduced and stored within the linear ion trap. After the ions have been stored, a single-phase RF voltage is supplied to all rods of a middle segment thus forming a three-dimensional ion trap, thereby collecting the ions in a spherical cloud within this middle segment. The collected analyte ions can then be reacted in the three-dimensional ion trap and the product ions resulting from the reactions can be ejected for mass analysis.

Method for operating three-dimensional RF ion traps with high ion capture efficiency

In a three-dimensional Paul RF ion trap at least one of the ring electrode and end cap electrodes is structured to produce a high capture efficiency for analyte ions introduced into the trap. The electrode structuring may be produced by an electrode surface profile having edges or protrusions, resulting in a scattering reflection of the introduced ions. Alternatively, at least one electrode may be formed by physically separate electrode components. In one embodiment, the trap can be switched between operating as a linear ion trap with good capture efficiency and operating as a three-dimensional ion trap with good ion reaction conditions.

Three-dimensional RF ion traps with high ion capture efficiency

The invention relates to methods and devices for measuring daughter ion spectra (also called fragment ion spectra or MS/MS spectra) in time-of-flight mass spectrometers with orthogonal injection of the ions. The invention filters the parent ions selected to be fragmented by a mass filter before they are injected into the time-of-flight mass spectrometer, fragments the selected ions in a first stage of the time-of-flight mass spectrometer within a collision cell filled with collision gas at collision energies between one and five kiloelectron-volts, further accelerates the fragment ions and measures the fragment ions in a second stage of the time-of-flight mass spectrometer.

Daughter ion spectra with time-of-flight mass spectrometers

The invention relates to methods and devices for the effective capturing of externally generated ions in an RF operated quadrupole ion trap. The invention involves applying a voltage consisting of positive and negative pulses, instead of a sinusoidal RF voltage, during the capturing process, with capturing intervals between each pulse in which the voltage is low.

Method and device for the capture of ions in quadrupole ion traps

The invention relates to the fragmentation of ions in ion traps filled with collision gas by exciting their axial oscillations in a dipole-shaped excitation field with a frequency mixture which covers the frequency of ion oscillations. The invention consists of ramping up the voltages of the frequency mixture for the dipolar excitation field, as a result of which, surprisingly, approximately the same fragmentation results are obtained for ions of different structures in the same fragmentation times as at a structurally specific optimal voltage applied at a constant level.

Fragmentation in quadrupole ion trap mass spectrometers

The invention relates to high performance ion traps used as mass spectrometers which in spite of a variable thermal load require a high constancy of the mass scale calibrated in. Ion traps consist at least of one ring electrode, two end cap electrodes, and suitable fixing elements which determine the distance between the electrodes. When exposed to a thermal load, the parts of the ion trap are subject to thermal expansion, which leads to a change in field intensities even if the applied RF voltage is constant, and thus to an apparant shift of masses. The invention consists of selecting the thermal expansion of the ion trap parts in such a way that when a constant RF voltage is applied, the field intensity within the trap remains constant by first approximation, in spite of the altering geometric form and expansion with changing operating temperature. In this way, displacement of the mass scale is avoided. To compensate an unavoidable thermal expansion .DELTA.r.sub.0 of the ring electrode with an inscribed radius r.sub.0 by a ratio .DELTA.r.sub.0 /r.sub.0, the distance z.sub.0 of the end cap poles from the center of the trap must become smaller by the proportional ratio .DELTA.z.sub.0 /z.sub.0 =-.DELTA.r.sub.0 /r.sub.0. This compensation can be achieved by a suitable design with suitably selected expansion coefficients for the ion trap electrode material and the material of the fixing elements.

Ion trap mass spectrometer of high mass-constancy

The invention consists of deriving the control of the space charge in the ion trap for the initial daughter ion spectrum from the filling rates of previous normal spectra, from the abundance ratio of the parent ions to be isolated to the total ions in the spectrum, and from the at least roughly known isolation and fragmentation yields. For further daughter ion spectra, the resulting measured overall filling rate with daughter ions may be used. The same applies in an analogue way to spectra of isolated ions or of ions from MS.sup.n processes.

Method for space-charge control of daughter ions in ion traps

The invention referres to analytic methods, the accuracy of which is increased by relating signals of analyte ions to those of reference ions, or by relating ion signals from measuring methods under special conditions to those of reference methods. If such 'comparative' analysis procedures are performed in ion trap mass spectrometers, problems arise with the low dynamic measuring range covered by one spectrum in such mass spectrometers and, if different spectra are compared, with the control of the space charge within the ion trap. The invention consists in acquiring analyte spectra and reference spectra in different acquisition procedures, alternating between both types of spectrum acquisitions as fast as possible, whereby control of the space charge in the ion trap proceeds separately for the spectra of both types, the control being related to previously acquired spectra of the same type. A similar procedure can be set up, if measuring results of two different sets of measurement conditions have to be compared. The control variable for the space charge control is derived from the last respective individual spectra scanned under the same conditions. Due to this fast interchanging of individual spectra, time-saving control of the space charge is achieved on the one hand, and a large dynamic measurement range is available on the other.

Methods of comparative analysis using ion trap mass spectrometers

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. Particularly ions from electrophoretically or chromatographically separated substance peaks should be able to be temporarily stored long enough until the mass spectrometric analyses have been concluded to the desired extent. Several temporary stores can collect the ions from several rapidly successive substance peaks. However, short-lasting substance peaks from laser desorptive or pyrolitic processes can also be thoroughly analyzed by means of temporary storage.

Temporary storage of ions for mass spectrometric analyses

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.

Method for controlling the ion generation rate for mass selective

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.

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Bremen, Germany

Michael Schubert