419results about "Spectrometer circuit arrangements" patented technology

A quantity of electrons that will be used in the ionization event in an FTICR MS is preprogrammed. When the number of electrons produced reaches that number, the electron beam is turned off. This approach assures that the same number of electrons are used for every measurement and eliminates the variations due to fundamental characteristics of the electron sourcere and the variations in temperature due to changing ambient conditions.

The present invention provides a radio frequency (RF) power supply in a mass spectrometer. The power supply provides an RF signal to electrodes of a storage device to create a trapping field. Such ion storage devices are often used to store ions prior to ejection to a subsequent mass analyzer. The RF field is usually collapsed prior to ion ejection. The present invention provides a RF power supply comprising: a RF signal supply, a coil arranged to receive the signal provided by the RF signal supply and to provide an output RF signal for supply to electrodes of an ion storage device, and a shunt including a switch operative to switch between a first open position and a second closed position in which the shunt including a switch operative to switch between a first open position and a second closed position in which the shunt shorts the coil output.

A circuit is described for applying RF and AC voltages to the elements or electrodes of an ion trap or ion guide. The circuit includes an RF transformer having a primary winding and a secondary winding. The secondary winding includes at least two filars. A broadband transformer adapted to be connected to a source of AC voltage applies AC voltage across the low-voltage end of two of the filars. Another broadband transformer connected to the filars at the high-voltage end provides a combined RF and AC output for application to selected electrodes. Also described is a circuit employing a multi-filar RF transformer and broadband transformers for applying RF and AC voltages to spaced rods of a linear ion trap. Also described is a circuit employing a multi-filar RF transformer and broadband transformers for applying RF and AC voltages to the electrodes in each section of a linear ion trap of the type having a center section and end sections, and different DC voltages to the electrodes in the end sections.

Chromatograms and mass spectra produced by an LC / MS system are analyzed by creating a two-dimensional data matrix of the spectral and chromatographic data. The two-dimensional matrix can be created by placing the spectra generated by the mass spectrometer portion of the LC / MS system in successive columns of the data matrix. In this way, the rows of the data matrix correspond to chromatographic data and the columns of the data matrix correspond to the spectra. A two-dimensional filter is specified and applied to the data matrix to enhance the ability of the system to detect peaks associated with ions. The two-dimensional filter is specified according to desired criteria. Rank-1 and rank-2 filters can be specified to improve computational efficiency. One method of applying the two-dimensional filter is through convolution of the data matrix with the two-dimensional filter to produce an output data matrix. Peaks corresponding to detected ions are identified in the output data matrix. Parameters of the peaks are determined and stored for later processing including quantitation, or simplification of chromatograms or spectra by, for example, identifying peaks associating with ions having retention times falling within a specified retention time window or having mass-to charge ratios falling within a specified mass-to-charge ratio window.

An electrospray ion source and method of operation includes the application of pulsed voltage to prevent electrolysis of analytes with a low electrochemical potential. The electrospray ion source can include an emitter, a counter electrode, and a power supply. The emitter can include a liquid conduit, a primary working electrode having a liquid contacting surface, and a spray tip, where the liquid conduit and the working electrode are in liquid communication. The counter electrode can be proximate to, but separated from, the spray tip. The power system can supply voltage to the working electrode in the form of a pulse wave, where the pulse wave oscillates between at least an energized voltage and a relaxation voltage. The relaxation duration of the relaxation voltage can range from 1 millisecond to 35 milliseconds. The pulse duration of the energized voltage can be less than 1 millisecond and the frequency of the pulse wave can range from 30 to 800 Hz.

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.

A mass spectrometer and methods for controlling a mass spectrometer are provided. In an exemplary embodiment, the mass spectrometer includes a plurality of discrete functional modules, each operable to perform a predetermined function of the mass spectrometer, wherein the modules are individually addressable and connected in a network. The mass spectrometer can also include a scheduler operable to introduce discrete packets of instructions to the network at predetermined times to instruct at least one module to perform a predetermined operation.

Disclosed is an apparatus for generating a periodically varying electrical signal for creating a periodically varying electrical field between electrodes of an ion mobility spectrometer. The apparatus includes an output port. A first tuned circuit is provided for being electrically coupled to an external power source and for, in isolation, providing a first periodically varying electrical signal having a first frequency. The first tuned circuit is coupled to the output port for providing an output electrical signal having a component at the first frequency thereto. A second tuned circuit is provided for being electrically coupled to an external power source and for providing a second periodically varying electrical signal having a second frequency different from the first frequency. The second tuned circuit is coupled to the first tuned circuit for varying the output electrical signal about the first periodically varying electrical signal.

A mass spectrometer is disclosed comprising a RF ion guide wherein in a mode of operation a continuous, quasi-continuous or pulsed beam of ions is orthogonally sampled from the ion guide and wherein the continuous, quasi-continuous or pulsed beam of ions is not axially trapped or otherwise axially confined within the RF ion guide. The ion guide is maintained, in use, at a pressure selected from the group consisting of: (i) 0.0001-0.001 mbar; (ii) 0.001-0.01 mbar; (iii) 0.01-0.1 mbar; (iv) 0.1-1 mbar; (v) 1-10 mbar; (vi) 10-100 mbar; and (vii) >100 mbar.

A mass spectrometer is disclosed comprising a RF ion guide wherein in a mode of operation a continuous, quasi-continuous or pulsed beam of ions is orthogonally sampled from the ion guide and wherein the continuous, quasi-continuous or pulsed beam of ions is not axially trapped or otherwise axially confined within the RF ion guide. The Ion guide is maintained, in use, at a pressure selected from the group consisting of: (i) 0.0001-0.001 mbar; (ii) 0.001-0.01 mbar; (iii) 0.01-0.1 mbar; (iv) 0.1-1 mbar; (v) 1-10 mbar; (vi) 10-100 mbar; and (vii) >100 mbar.

Circuits for correcting base line shift of the detector coupling circuit of a TOFMS provide gain and impedance characteristics that compensate for the AC coupling effect of the detector. In one circuit, base line correction is achieved by injecting a current equal to that which flows due to the buildup charge in the detectors AC coupling network. In another circuit, the current source drives an integrator which is coupled to the signal path to reduce the detector AC coupling effects. In another circuit, a low noise amplifier utilizes a feedback network that reduces the detector AC coupling effects. In yet another circuit, an operational amplifier is employed to reduce the detector AC coupling effects.

An ion guide or mass analyser is disclosed comprising a plurality of electrodes having apertures through which ions are transmitted in use. A pseudo-potential barrier is created at the exit of the ion guide or mass analyser. The amplitude or depth of the pseudo-potential barrier is inversely proportional to the mass to charge ratio of an ion. One or more transient DC voltages are applied to the electrodes of the ion guide or mass analyser in order to urge ions along the length of the ion guides or mass analyser. The amplitude of the transient DC voltage applied to the electrode may be increased with time so that ions are caused to be emitted from the ion guide or mass analyser in reverse order of their mass to charge ratio.

The present invention provides methods and electronic circuits for a chemical analyzer, for example, a mass spectrometer, which provide generated signals that are maintained to a required level of precision. A user may specify the required precision for the signals which operate the spectrometer and may specify the required precision for the mass analysis, either explicitly or by choosing a predefined configuration. The spectrometer will then generate the signals to the required precision despite changes in operating conditions, environmental conditions, component aging and degradation, or other nonfailure effects that otherwise affect analyzer calibration and signal output. The electronic circuits incorporate signal monitoring to maintain closed-loop signal control. The closed-loop control includes a feedback path which may include discrete components and may include software enabling a processor to adjust the generated signals to maintain the required precision of the signals and analysis. Further, the spectrometer may monitor signals and analyze and store data in order to predict future performance, including precision, analysis limitations, impending component degradation or failure, or another parameter associated with a component or signal of the spectrometer. Specifically, a range for a particular parameter may be specified and a indication provided to a user when the parameter exceeds the specified range.

An apparatus for electronically controlling a quadrupole in a mass spectrometer, comprises radio frequency (RF) drive circuitry and direct current (DC) drive circuitry coupled to a quadrupole, an RF control loop associated with the RF drive circuitry, a DC control loop associated with the DC drive circuitry, and control loop circuitry associated with the DC control loop, the control loop circuitry configured to alter a response of the DC control loop during a settling time period of a step response such that ion transmission through the quadrupole is greater during the settling time than if the response of the DC control loop during the settling time is unaltered.