RU2393579C1 - Mass spectrometre - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: proposed device comprises ion mobility spectrometre, ion-optical lenses, interface of differential pump-out, time-of-flight analyser and ion detector. Note here that ion mobility spectrometer comprises ion formation chamber, drift tube with aperture element, ion gate, drift zone, gas curtain zone of mass spectrometre, drift gas inlet and power supply. Ion source of mass spectrometre comprises axially symmetric casing with walls accommodating radially-directed sample intake and ionisation device with ionising agents. Point whereat said intake device axes intersect is located opposite the apex of aperture element representing a convex-face wall with hole to intake ion at its top. Time of flight analyser represents a cylindrical condenser accommodating assembly of orthogonal acceleration with ejector electrode and ion detector.

EFFECT: higher sensitivity and reduced sizes.

4 cl, 3 dwg

Description

The invention relates to methods for ion separation, to methods for separation by mass spectrometry, namely, charged particle spectrometers, to spectrometers operating on the principle of measuring the flight time of ions, in particular to determining the composition of liquid and gas samples, and can be used in medicine, pharmaceuticals, forensics, analysis of environmental objects.

A known mass spectrometer comprising an ion mobility spectrometer, ion-optical lenses, a differential pumping interface, a time-of-flight mass-reflectron type analyzer and an ion detector. U.S. Patent No. 7095014, IPC B01D 59/44, 2006.

A known time-of-flight mass spectrometer containing an ion source, an ion fragmentation device, a mass reflectron, a position-sensitive detector connected to a time-of-flight mass spectrometer, a time controller, a data processing system. US patent No. 7084395, IPC H01J 49/40, 2006. Prototype.

Both the analog and the prototype have common disadvantages, because The mass reflectron causes limitations on sensitivity due to low current transmission and restrictions on the duty cycle of continuous ion fluxes.

The invention eliminates these disadvantages.

The technical result of the invention is to increase the sensitivity and reduce the size of the device.

The technical result is achieved in that in a mass spectrometer containing an ion mobility spectrometer, ion-optical lenses, a differential pumping interface, a time-of-flight analyzer and an ion detector, an ion mobility spectrometer, contains an ionization chamber, a drift tube with an aperture element, an ion gate, a drift region , the gas region of the mass spectrometer curtain, the drift gas inlet, the power supply system, the ion source of the mass spectrometer contains an axially symmetric ionizer body, an ion on the body walls of the isator, radially directed devices for introducing and ionizing the sample of the analyte with ionizers are installed, the point of intersection of the axes of the input devices is located opposite the top of the aperture element, made in the form of a convex wall with an ion input hole at its top, and the time-of-flight analyzer is made in the form of a cylindrical capacitor which has an orthogonal acceleration assembly with a push electrode and an ion detector. A screen is installed in the linear ion guide with the possibility of changing its potential. The device for input and ionization of the sample of the analyte contains ionizers in the form of an electrospray, and / or ionizer by corona discharge, and / or a photoionizer, and / or laser ionizer, and / or input of a spray of liquid sample, and / or input of gas samples, and / or substrate for desorption from the surface.

The invention is illustrated in drawings 1-3.

Figure 1 schematically shows a device for analyzing gas samples, where 1 is an electrospray (in the OFF position), 2 is a corona discharge ionizer (in the ON position), 2.1 is a corona discharge ionizer needle, 3 is a photoionizer (in the ON position) 4 - a device for introducing gas samples (in the ON position), 5 - a spray of liquid samples (in the OFF position), 6 - an ionizer body, 7 - an ionization chamber, 8 - a convex-shaped wall, 9 - an opening at the apex of the convexity of the wall, 10 - desolvation region, 11 — inlet ion gate or concentrator, 12 — drift region, 13 — exhaust th ion shutter, 14 - heater, 15 - channel for pumping drift gas and samples, 16 - channel for introducing chilled air for operation at low temperature or rapid temperature changes, 17 - channel for outputting chilled air, 18 - body of the ion mobility mass spectrometer, 19 - analyte, 20 - gas region of the mass spectrometer curtain, 20.1 - gas of the mass spectrometer curtain used as drift gas, 21 - first stage of the differential pump interface of the mass spectrometer, 21.1 - hole of the first stage of the differential interface pumping, 22 - second stage of the differential pumping interface, 22.1 - skimmer of the second stage of the differential pumping interface, 22.2 - hole of the second stage of the differential pumping interface, 22.3 - ion optics of the second stage of the differential pumping interface of the mass spectrometer, 22.4 hole in the wall between the second stage of the differential pumping interface pumping and the mass analyzer chamber, 22.5 - wall between the second stage of the differential pumping interface and the mass analyzer chamber, 23 - orthogonal acceleration unit, 24 - cylindrical capacitor (rotary axially symmetric mass analyzer), 24.1 - input window of the rotational axially symmetric mass analyzer, 24.2 inner lining of the revolving axially symmetric mass analyzer, 24.3 outer lining of the revolving axially symmetric mass analyzer, 24.4 - central path ion, 24.5 - exit window of a rotary axially symmetric mass analyzer, 25 - linear ion guide, 25.1 - linear ion guide screen, 26 - ion detector, 27 - rotary vane pump, 28, 29 - turbomolecular pumps, 30 - high ovoltnye modules 31 - controller 32 - the controller of the intake valve or the ion accumulator ions 33 - heater controller, 34 - the outlet of the ion shutter controller, 35 - TTL pulse generator, 36 - controller unit orthogonal acceleration, 37 - integrating recorder.

Figure 2 schematically shows a device for analyzing liquid samples, where 1 is the electrospray (in the ON position), 1.1 is the input channel of the capillary of the sample supply, 1.2 is the needle of the electrospray, 1.3 is the channel for the supply of gas to the sprayer, 1.4 is the channel for supplying high voltage, 2 - a corona discharge ionizer (in the OFF position), 3 - a photoionizer (in the ON position), 4 - a gas sample input device (in the ON position), 5 - a liquid sample atomizer (in the OFF position), 6 - an ionizer body, 7 - ionization chamber, 8 - convex-shaped wall, 9 - hole at the apex of the convexity of the wall 10 — desolvation region, 11 — ion inlet gate or concentrator, 12 — drift region, 13 — ion gate, 14 — heater, 15 — drift gas and sample pumping channel, 16 — chilled air inlet channel for operation at low temperature or a quick change of temperature, 17 — channel of the outlet of cooled air, 18 — body of the ion mobility mass spectrometer, 19 — analyte, 20 — gas region of the mass spectrometer curtain, 20.1 — curtain gas used as a drift gas, 21 — first stage of the interface differential from the mass spectrometer, 21.1 - the hole of the first stage of the differential pumping interface, 22.1 - the skimmer of the second stage of the differential pumping interface, 22.2 - the hole of the second stage of the differential pumping interface, 22.3 - ion optics of the second stage of the differential pumping mass interface spectrometer, 23 — orthogonal acceleration unit, 23.1 — push electrode, 24 — cylindrical capacitor (reverse axial-symmetric mass analyzer), 24.1 — inner lining ndric condenser, 24.2 - the outer lining of the cylindrical capacitor, 25 - the linear ion guide, 25.1 - the screen of the linear ion guide, 26 - ion detector, 27 - rotary vane pump, 28, 29 - turbomolecular pumps, 30 - high-voltage modules, 31 - controller, 32 - an inlet ion gate or ion storage controller, 33 - a heater controller, 34 - an exhaust ion gate controller, 35 - a TTL pulse generator, 36 - an orthogonal acceleration unit controller, 37 - an integrating recording device.

Figure 3 schematically shows a device using a desorption substrate used with ionization-stimulated matrix laser desorption (MALDI), laser desorption from a porous quartz surface (DIOS) stimulated by electrospray desorption (DESI, shown in the drawing), where 1 is an electrospray (in ON position), 1.1 - input channel of the sample supply capillary, 1.2 - electrospray needle, 1.3 - spray gas supply channel, 1.4 - high voltage supply channel, 2 - corona discharge ionizer (in the OFF position), 6 - housing isator, 7 - ionization chamber, 8 - convex-shaped wall, 9 - hole at the top of the convexity of the wall, 10 - desolvation region, 11 - inlet ion gate or concentrator, 12 - drift region, 13 - outlet ion gate, 14 - heater, 15 - a drift gas and sample pumping channel, 16 - a chilled air inlet channel for operation at a low temperature or a quick temperature change, 17 - a chilled air outlet channel, 18 - an ion mobility mass spectrometer case, 19 - an analyte, 20 - a gas region mass spectrum curtains tra, 20.1 - curtain gas used as a drift gas, 21 - first stage of the differential pumping interface of the mass spectrometer, 21.1 - hole of the first stage of the differential pumping interface, 22 - second stage of the differential pumping interface, 22.1 - skimmer of the second stage of the differential pumping interface, 22.2 - hole of the second stage of the differential pumping interface, 22.3 - ion optics of the second stage of the differential pumping interface of the mass spectrometer, 23 - orthogonal accelerator, 23.1 - pushing electrode of the orthogonal assembly acceleration, 24 - rotational axially symmetric mass analyzer (cylindrical condenser), 24.1 - the inner lining of the cylindrical capacitor, 24.2 - the outer lining of the cylindrical capacitor, 25 - the linear ion guide, 25.1 - the screen of the linear ion guide, 27 - rotary vane pump, 28 , 29 - turbomolecular pumps, 30 - high-voltage modules, 31 - controller, 32 - inlet ion gate or ion storage controller, 33 - heater controller, 34 - exhaust ion gate controller, 35 - TTL pulse generator, 36 - knot controller orthogonal acceleration launcher, 37 — integrating recording device, 38 — desorber, 38.1 — desorption substrate, 38.2 — high voltage supply channel.

The device operates as follows.

When working with an ionizer based on corona discharge 2 or with a photoionizer 3, the atomizer 1 is turned off (Figure 1). The analyte 19 in the gas phase is fed through the inlet of gas samples 4. The analyte 19 in the liquid phase is introduced through an orthogonally located atomizer of liquid samples 5.

In the ionization chamber 7 at atmospheric pressure, ions are generated by corona discharge or photoionization, which are fed through the hole 9 on the top of the convex wall 8 to the desolvation region 10. Ions pass through the inlet ion gate or concentrator 11 and enter the drift region 12 at atmospheric pressure. Drift gas (high purity nitrogen or dry purified atmospheric air with a flow rate of 0.5-2 l / min) is constantly supplied to the drift region 12, which, as a curtain gas, prevents neutral particles from entering the mass spectrometer.

The drift tube comprises a desolvation region 10 and a drift region 12, separated by an intake shutter or phase 11 concentrator.

The regions of desolvation 10 and drift 12 in the radial direction are limited by a set of cylindrical electrodes forming an electric field. Moving under the influence of an electric field, at atmospheric pressure, the ions of the analyte 19 collide with the molecules of the drift gas. In the region of desolvation 10, the ions are drained and declustered. The intake gate or phase 11 concentrator forms a spatially localized group containing the ions of the analyte 19. This group, moving under the influence of an electric field in the drift region in the countercurrent flow of the drift gas, is divided into a series of groups containing components with different degrees of retention on the molecules of the drift gas. Each of these groups reaches the exhaust ion gate 13 during the drift time, associated with the mobility of the components that form this group, and falls into the gas region of the curtain 20, where it is freed from neutral particles and is gasdynamically concentrated on the hole 21.1 of the first stage of the differential pumping interface 21.

Through the hole 21.1, the ions of the analyte 19 enter the first stage of the differential pumping interface 21, providing an intermediate pressure between the pressure of the second stage and the atmospheric pressure of the drift pipe, where they are concentrated on the hole 22.2 of the second stage of the differential pumping interface 22 in the skimmer of the second stage of the differential pumping interface 22.1.

Through the hole 22.2, the sample ions enter the second stage of the differential pumping interface 22, providing an intermediate pressure between the pressure of the first stage of the differential pumping interface 21 and the working pressure of the mass spectrometer. In the second stage of the differential pumping interface 22 of the mass spectrometer, ions are focused by ion optics 22.3 of the second stage of the differential pumping interface 22 into a plane-parallel beam and concentrated on the hole 22.4 in the wall between the second stage of the differential pumping interface 22 and the mass analyzer chamber 22.5.

After passing through hole 22.4, ions in the form of a plane-parallel beam in the direction of the Y axis enter the orthogonal acceleration assembly 23 of the cylindrical capacitor 24 parallel to the symmetry axis of the mass analyzer Z. Moving parallel to the symmetry axis of the Z analyzer, the ions fill the orthogonal acceleration assembly 23. On the ejection electrode of the orthogonal assembly of acceleration 23.1, the controller of the orthogonal acceleration unit 37 serves a buoyant pulse, causing the ions to move perpendicular to their initial movement in the direction of the input window 24.1 of the rotational axially symmetric mass analyzer 24 along the Y axis. The ejection pulse blocks the ion beam from the interface for the duration of the application and forms a short ion packet that preserves the velocity component v _x in the direction of the X axis and acquires the velocity component v _y in the direction of the Y axis Moving in the direction of the Y axis, the beam through the inlet window 24.1 enters the reverse axially symmetric mass analyzer 24. Under the action of the centripetal force due to the axially symmetric field formed by the plates 24.2 and 24.3, ions acquire acceleration directed to the axis of symmetry of the Z analyzer and move in a spiral, moving around a circle near the central path 24.4 and linearly along the Z axis. Ions leave the axially symmetric mass analyzer 24 through the exit window 24.5 and enter the linear ion conductor 25, protected screen 25.1. The potential of the screen of the linear ion guide 25.1 can be changed relative to the potential of the average trajectory, which allows you to change the length of the linear section necessary to compensate for the aberrations of the time of flight. The efficiency of the use of ions of the analyte is regulated by the orthogonal acceleration unit 23.

Ions leaving the linear ion guide 25 are detected by a secondary electron multiplier 26. The multiplier signal is recorded by an integrating recording device 37. The integrating recording device 37 generates a signal that controls the controller 36 of the orthogonal acceleration unit 23.

When working with electrospray 1 (figure 2), an ionizer based on corona discharge 2, a photoionizer 3, an input device for gas samples 4 and a spray of liquid samples 5 are turned off (set to OFF). The analyte 19 in the liquid phase is fed through channel 1.1. Carrier gas supplied through channel 1.3 is used for atomization. Spraying is carried out in an electric field created between the tip of the needle 1.2 and the wall 8, which has a convex shape. Born ions through the hole 9 at the top of the convex wall 8 enter the desolvation region 10, pass through the inlet ion gate or concentrator 11, and enter the drift region 12.

When working with stripper 38 (Fig. 3), the analyte is applied to the substrate 38.1, and desorption and ionization are carried out with a laser installed in place of electrospray 1 (MALDI and DIOS methods), or electrospray of solvent with electrospray 1 (DESI method). The solvent 39 in the liquid phase is fed through channel 1.1. Carrier gas supplied through channel 1.3 is used for atomization. Spraying is carried out in an electric field created between the tip of the needle 1.2, the substrate 38.1 and the wall 8 having a convex shape. A buoyant potential is applied between the substrate 38.1 and the wall 8. Born ions through the hole 9 at the top of the convex wall 8 enter the desolvation region 10, pass through the inlet ion gate or concentrator 11 and enter the drift region 12.

Recording of the analytical signal is continuous. A predetermined number of time-of-flight spectra is added in accordance with the selected information compression algorithm. The resulting one-dimensional data array is transformed into a two-dimensional array.

The resulting signal is a two-dimensional distribution of intensity over drift time and flight time. For a fixed value of the flight time, this distribution is transformed into a one-dimensional distribution of the drift time (mass selective chromatogram of the sample). For a fixed value of the drift time, this distribution is transformed into a one-dimensional distribution of the time of flight (the time-of-flight mass spectrum of the components of the sample corresponding to the selected drift time).

The chromatogram is transformed into a distribution of reduced mobilities. Time-of-flight spectra are transformed into mass spectra.

The components are identified by the reduced mobility and the mass corresponding to the peak maximum, and their concentration in the initial sample of the analyte is determined by the amplitude or peak area 19. Since the characteristic time of recording the mass spectrum (tens of microseconds) is much less than the characteristic time of recording the mobility spectrum (tens of milliseconds) , during the release of one component from the ion mobility spectrometer, the device manages to record several mass spectra. For each group of ions separated by mobility, a mass spectrum is recorded. Components are identified by 3-dimensional information (reduced mobility, mass, intensity).

The increase in sensitivity is achieved due to the high current transmission due to focusing in three parameters. Spiral trajectory allows you to separate the node orthogonal acceleration 23 and the ion detector 26 in different planes, which increases the efficiency of use of the analyte 19.

The reduction in overall dimensions is achieved due to the spiral motion of ions in a cylindrical analyzer.

Claims (4)

1. A mass spectrometer comprising an ion mobility spectrometer, ion-optical lenses, a differential pumping interface, a time-of-flight analyzer and an ion detector, characterized in that the ion mobility spectrometer comprises an ionization chamber, a drift tube with an aperture element, an ion gate, a drift region, a region the gas curtain of the mass spectrometer, the introduction of drift gas, the power system, the ion source of the mass spectrometer contains an axially symmetric ionizer body, mounted on the walls of the ionizer body ialically directed device for input and ionization of the sample of the analyte with ionizers, the point of intersection of the axes of the input devices is located opposite the top of the aperture element, made in the form of a convex wall with an ion input hole at its top, and the time-of-flight analyzer is made in the form of a cylindrical capacitor in which an orthogonal acceleration unit with a push electrode and an ion detector. 2. The mass spectrometer according to claim 1, characterized in that a linear ion guide is installed between the cylindrical capacitor and the ion detector. 3. The mass spectrometer according to claim 1, characterized in that a screen is installed in the linear ion guide with the possibility of changing its potential. 4. The mass spectrometer according to claim 1, characterized in that the input and ionization devices of the sample of the analyte contain ionizers in the form of an electrospray and / or ionizer by corona discharge, and / or a photoionizer, and / or laser ionizer, and / or a liquid atomizer inlet samples, and / or injection of gas samples, and / or substrates for desorption from the surface.

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