Thermo Finnigan LLC

Thermo Finnegan LLC

Harald Oser

Oleg Silivra

Bennett S Kalafut

Alan E Schoen

Joshua T Maze

Terry N Olney

Raman Mathur

Mikhail V Ugarov

Qingyu Song

Paul I Hendricks

A first multipole assembly includes a first plurality of rod electrodes arranged about an axis and configured to confine ions radially about the axis. A second multipole assembly disposed adjacent to the first multipole assembly includes a second plurality of rod electrodes arranged about the axis and configured to confine the ions radially about the axis. An orientation of the first multipole assembly about the axis is rotationally offset relative to an orientation of the second multipole assembly about the axis.

Multipole assembly configurations for reduced capacitive coupling

A multipole ion guide includes a plurality of electrodes disposed about a longitudinal axis of the device so as to define an ion transmission volume for transmitting ions along a length of the device between opposite inlet and outlet ends. An electronic controller is operably connected to an RF power source and to at least some of the electrodes and is configured to apply at least an RF potential to the electrodes. During use the electrodes generate an RF-only field along a first portion of the device and an axial DC field along a second portion of the device. Ions are focused radially inward toward the longitudinal axis of the device by the RF-only field within the first portion of the device prior to and/or subsequent to experiencing the axial DC field within the second portion of the device.

Collision cell with enhanced ion beam focusing and transmission

A mass spectrometer includes a collision cell and a system controller. The collision cell includes a plurality of rod pairs configured to generate pseudopotential well through the application of radio frequency potentials to the rod pairs. The collision cell configured to generate a target fragment from a parent ion by colliding the parent ion with one or more gas molecules. The system controller is configured to set a radio frequency amplitude of the radio frequency potentials to a default amplitude; monitor the production of a target fragment ion while adjusting the collision energy; set the collision energy to optimize the production of the target fragment ion; apply a linear full range ramp to the radio frequency amplitude to determine an optimal radio frequency amplitude; and set the radio frequency amplitude to the optimal radio frequency amplitude for the parent ion, target fragment ion pair.

Optimizing quadrupole collision cell RF amplitude for tandem mass spectrometry

A method of operating a quadrupole mass filter is disclosed. A first set of RF and resolving DC voltages are applied to electrodes of a quadrupole mass filter to selectively transmit first ions having a first mass-to-charge ratio (m/z). A second set of RF and resolving DC voltages are applied to electrodes of the quadrupole mass filter to selectively transmit second ions having a second m/z. Detection of the second ions is initiated after completion of a settling time. The settling time is determined in accordance with the relationship: Eq. 1, where tis the settling time, (m/z)is the first mass-to-charge ratio, (m/z)is the second mass-to-charge ratio and A, B and C are empirically derived coefficients.

Method and apparatus for improved mass spectrometer operation

A method for operating a mass spectrometer so as to detect or quantify analytes, comprises: (a) identifying a selected-reaction-monitoring (SRM) transition to be used for each respective analyte; (b) determining a time duration required for a fragmentation reaction corresponding to each identified transition to proceed to a threshold percentage of completion; and (c) for each analyte, performing the steps of (i) isolating ions corresponding to a precursor-ion mass-to-charge (m/z) ratio of the respective transition; (ii) fragmenting the respective isolated ions in one of two fragmentation cells or fragmentation cell portions; and (ii) mass analyzing for fragment ions corresponding to a product-ion m/z ratio of the respective transition, wherein, for each analyte, the fragmentation cell or fragmentation cell portion that is used for fragmenting the isolated ions is determined from the time duration determined for the respective analyte.

Methods for tandem collision-induced dissociation cells

A mass spectrometry method comprises: introducing a first portion of a sample of ions including precursor ions comprising a first precursor-ion mass-to-charge (m/z) ratio into a first mass analyzer; transmitting the precursor ions from the first mass analyzer to a reaction or fragmentation cell such that a first population of product ions are continuously accumulated therein over a first accumulation time duration; initiating release of the accumulated first population of product ions from the reaction or fragmentation cell; continuously transmitting the released first population of product ions from the reaction cell to a second mass analyzer; transmitting a portion of the released first population of product ions comprising a first product-ion m/z ratio from the second mass analyzer to a detector; and detecting a varying quantity of the product ions having the first product-ion m/z ratio for a predetermined data-acquisition time period after the initiation of the release.

Method for mass spectrometer with enhanced sensitivity to product ions

Method for operating a mass spectrometer includes supplying a quantity of ions to an ion detector. The ion detector can include a conversion dynode operating in a first polarity and an electron multiplier. The method further includes adjusting the gain of the electron multiplier to determine a first set of calibration parameters, and calculating a second set of calibration parameters for the electron multiplier from the first set of calibration parameters. The second set of calibration parameters are for a second polarity of the conversion dynode. The method can further include configuring the ion detector to operate at the second polarity based on the second set of calibration parameters, and supplying ions of the second polarity to the mass spectrometer, and detecting an ion at a particular mass to charge ratio using the ion detector.

Systems and methods for calibrating gain in an electron multiplier

A collision cell has a plurality of rod electrodes arranged in opposed pairs around an axial centerline and a plurality of drag vanes arranged in the interstitial spaces between the rod electrodes. Operating the collision cell includes, applying a rod offset voltage to the rod electrodes, and varying an offset voltage applied to the drag vanes to identify a vane offset voltage with a maximum intensity for the transition. The method further includes varying a drag field by adjusting the voltages applied to drag vane terminals in opposite directions to identify a drag field value with a cross talk below a cross talk threshold, varying the vane offset voltage by adjusting the voltages applied to the drag vane terminals to maximize the intensity of the transition while preserving the drag field, and operating the collision cell at the vane offset voltage and drag field to monitor the transition.

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San Carlos, CA, United States of America

Harald Oser