Tandem triple-quadrupole mass spectrometer

Description

[0001] The utility model relates to the field of scientific instrumentation, in particular to mass spectrometry.

[0002] A mass spectrometric interface is known that has increased sensitivity and reduced chemical background, in which a flow of partially solvated particles is transported along a tortuous path into a region of flow disturbance, where ions and neutral molecules collide and, under conditions of wall heating, are desolvated and can also undergo stimulated molecular reactions. Patent US8946622 B2 (IPC H01J 49 / 00, H01J 49 / 04, H01J 49 / 06, declared 08 / 29 / 2013, published 02 / 03 / 2015). In general, the mass spectrometric interface requires a significant flow of curtain gas, a bulky nitrogen generator compressor, and significant energy consumption for its operation.

[0003] A tandem mass spectrometer is known, the interface of which includes three devices located on a common axis transporting ions at pressures of 1 Torr, 0.2 Torr and 10 -3Torr transporting ions into the analyzer chamber with a pressure of 10 -6 Torr, where the quadrupole mass filters and collision cell are located. Patent US 9343280 B2 (IPC H01J 49 / 00, H01J 49 / 24, filed September 8, 2008, published May 17, 2016). The prototype is quite complex, bulky, and requires a three-stage turbomolecular pump for operation.

[0004] The objective of the utility model is to create a design for a tandem three-quadrupole mass spectrometer that ensures the ability to achieve high sensitivity even when using four vacuum pumps.

[0005] The technical result of the utility model is the achievement of high sensitivity when using three pumping directions with independent vacuum pumps, including two separately located turbomolecular pumps.

[0006] The technical result is achieved in that the vacuum system is made in the form of a monolithic vacuum chamber with a lid secured by screwing, the monolithic vacuum chamber is secured to the housing with screw connections - by screwing; pressure control means are secured to the vacuum chamber by screwing, the monolithic vacuum chamber contains three cavities-sections, all three cavities-sections are hermetically sealed with one lid of the vacuum chamber secured by screwing, the first forevacuum pump is connected to the first cavity-section of the vacuum chamber through a vacuum hose and fittings, secured to the housing by screwing, pumping out this volume with a capacity of 40-80 m 3 / h, the second cavity-section of the vacuum chamber is pumped out by the first turbomolecular vacuum pump attached to the vacuum chamber by means of screw connections with a capacity of 260-300 l / s, the rotor axis of which is located orthogonally to the optical axis of the transport hexapole, the third cavity-section of the vacuum chamber is pumped out by the second turbomolecular pump with a capacity of 390-500 l / s, the rotor axis of which is located parallel to the optical axis of the system of quadrupole mass filters with radio frequency segments, and the second turbomolecular pump is secured by screwing on the wall closest to the charged particle detector in the area of ​​the third cavity-section of the vacuum chamber, perpendicular to the axis of the ion-optical system, and a second forevacuum pump with a capacity of 40-80 m is connected to the output of both turbomolecular pumps through a vacuum hose and fittings by screwing 3 / h; the analytical system includes a resistive transport capillary, a skimmer, a transport hexapole, a diaphragm, a first quadrupole mass filter with a radio frequency segment, a hexapole-based collision cell, a second quadrupole mass filter with a radio frequency segment, and a charged particle detector.

[0007] High sensitivity is achieved by using three pumping directions with independent vacuum pumps by locating the second turbomolecular pump in close proximity to the charged particle detector and using a resistive transport capillary and skimmer together with a transport hexapole.

[0008] The essence of the utility model is explained in Fig. 1-4. Fig. 1 shows a diagram of a tandem three-quadrupole mass spectrometer, where 1 is a housing, 2 is a control system, 3 is an analytical system, 4 is a vacuum system, 5 is the first forevacuum pump, 6 is the second forevacuum pump, 41 are screw connections between the units of the tandem three-quadrupole mass spectrometer. In Fig. 2 shows the vacuum system of the tandem triple-quadrupole mass spectrometer, where 7 is the first cavity section of the vacuum chamber, 8 is the second cavity section of the vacuum chamber, 9 is the third cavity section of the vacuum chamber, 10 is the first turbomolecular pump, 11 is the second turbomolecular pump, 12 is a low-vacuum pressure gauge, 13 is a high-vacuum pressure gauge, 14 are vacuum pipelines and connecting fittings, 15 is an RS 485 interface, 16 is a digital controller, 40 is a monolithic vacuum chamber. In Fig.3 shows the control system of the tandem triple-quadrupole mass spectrometer, where 17 is the controller of the charged particle detector, 18 is the alternating voltage former of the first quadrupole mass filter and the transport hexapole, 19 is the alternating voltage former of the second quadrupole mass filter and the collision cell, 20 is the constant voltage former of the quadrupole mass filters, 21 is the low voltage former, 22 is the high voltage former, 23 is the heater controller, 24 is the flow controller, 25 is the inductor coil of the first mass filter, 26 is the inductor coil of the second mass filter, 27 is the common power module, 28 are the power terminals of the analytical system elements, 29 is the motherboard, 39 is the crate, 42 are the screw connections between the motherboard 29 and the crate 39. In Fig.4 shows the analytical system, where 30 is the electrospray source, 31 is the resistive transport capillary, 32 is the skimmer, 33 is the transport hexapole, 34 is the diaphragm, 35 is the first quadrupole mass filter with a radio frequency segment, 36 is the hexapole-based collision cell, 37 is the second quadrupole mass filter with a radio frequency segment, 38 is the charged particle detector, 40 is the monolithic vacuum chamber.

[0009] The device operates as follows.

[0010] In the housing 1 (Fig. 1) are located all the units of the control system 2, all the units of the analytical system 3, all the units of the vacuum system 4. All the units of the control system 2 are connected to the crate 39 by a screwing operation, and the crate 39 itself is connected to the housing 1 by a screwing operation 41. All the units of the vacuum system 4, with the exception of the first forevacuum pump 5 and the second forevacuum pump 6, being connected to each other by screwing, are connected to the housing 1 by a screwing operation. The first forevacuum pump 5 and the second forevacuum pump 6 are connected by a screwing operation directly to the housing 1, and are connected to the remaining elements of the vacuum system by screwing using vacuum pipelines and connecting fittings 14. All units of the analytical system, being connected to each other by screwing, are connected to the elements of the vacuum system (with the exception of the forevacuum pumps) by a screwing operation.

[0011] The vacuum system 4 consists of a monolithic vacuum chamber 40, attached to the body 1 by a screwing operation, the first cavity-section of the vacuum chamber 7 (Fig. 2), is pumped out by the first forevacuum pump 5 with a capacity of 40-80 m 3 / h, the second cavity-section of the vacuum chamber 8 is pumped out by a turbomolecular vacuum pump 10 with a capacity of 260-300 l / s, the third section of the vacuum chamber 9 is pumped out by a turbomolecular pump 11 with a capacity of 390-500 l / s. Both turbomolecular pumps are pumped out by a second forevacuum pump 6. A low-vacuum pressure gauge 12 is used to control the pressure at the outlet of the turbomolecular pumps, and a high-vacuum pressure gauge 13 is used to control the pressure in the area of ​​the charged particle detector. The individual elements of the vacuum system are connected to each other by vacuum pipelines and connecting fittings 14 by a screwing operation. Control of turbomolecular pumps 10 and 11 and polling of pressure gauges 12 and 13 is carried out through a serial interface 15 by a digital controller 16 of control system 2.All components of the vacuum system, with the exception of the forevacuum pumps, are connected to the monolithic vacuum chamber 40 by screwing, and the monolithic vacuum chamber is connected to the housing 1 by screwing. The first turbomolecular pump 10 and the second turbomolecular pump 11 are connected directly to the housing by screwing.

[0012] Control system 2 includes all electronic modules controlling the elements of analytical system 3 and vacuum system 4. Digital controller 16 (Fig. 3) provides overall control of all active devices of the tandem triple-quadrupole mass spectrometer via the RS485 serial interface. Charged particle detector controller 17 provides the generation of the required supply voltages for the charged particle detector, as well as recording the received analytical signal.The alternating voltage former of the first quadrupole mass filter and transport hexapole 18, the alternating voltage former of the second quadrupole mass filter and collision cell 19, the constant voltage former of the quadrupole mass filters 20, the inductor of the first mass filter 25 and the inductor of the second mass filter 26 together provide the necessary supply voltages of the quadrupole mass filters, as well as the alternating voltages of the transport hexapole and the hexapole-based collision cell. The low voltage former 21 provides power to the low-voltage elements of the ion optics. The high voltage former 22 provides power to the electrospray source.Heater controller 23 supplies power to the nebulizer gas and curtain gas heaters of the ion source; flow controller 24 controls the flows of nebulizer gas (purified air), curtain gas (pure nitrogen), and collision gas (pure nitrogen). Common power module 27 supplies power to all control system components. The controlled components of analytical system 3 are connected to power terminals 28 located on motherboard 29. Crate 39 serves as a frame to which all of the aforementioned control system components are screwed together and which is secured to housing 1 by screwing.

[0013] The analytical system of the mass spectrometer 3 consists of an ion electrospray source 30, a resistive transport capillary 31 transporting ions from the atmospheric pressure region to the first cavity-section of the vacuum chamber 7, a skimmer 32 transporting ions from the first cavity-section of the vacuum chamber 7 to the second cavity-section of the vacuum chamber 8, a transport hexapole 33 transporting ions through the second cavity-section of the vacuum chamber 8, a diaphragm 34 transporting ions from the second cavity-section of the vacuum chamber 8 to the third cavity-section of the vacuum chamber 9, as well as a first quadrupole mass filter with a radio frequency segment 35 located in the third cavity-section of the vacuum chamber 9, a collision cell based on a hexapole 36, a second quadrupole mass filter with a radio frequency segment 37, a charged particle detector 38.The elements of the control system 3 are connected by a screwing operation with the monolithic vacuum chamber 40 of the vacuum system 4, which is connected by a screwing operation with the body 1.

[0014] The sample is transferred to an electrospray ion source 30, in which a liquid stream at atmospheric pressure is passed through a metal tube under high voltage. At the tube's outlet, charged droplets are formed and heated to 300°C by a strong electrostatic field. This causes the solvent to evaporate, reducing the volume of the charged droplets, and producing molecular ions of the analyte without the associated solvent.The molecular ions of the substance being analyzed are focused at the entrance to the capillary 31 and are transported from the region of atmospheric pressure into the first cavity-section of the vacuum chamber 7, where they are focused on the opening of the skimmer and are transported from the first cavity-section of the vacuum chamber into the second cavity-section of the vacuum chamber 8, where they enter the transport hexapole 33, by which they are transported through the second cavity-section of the vacuum chamber 8 and are focused on the opening in the diaphragm 34, through which they are transported from the second cavity-section of the vacuum chamber 8 into the third cavity-section of the vacuum chamber 9, focusing on the entrance of the first quadrupole mass filter with radio frequency segment 35.

[0015] The first quadrupole mass filter with radio frequency segment 35 can operate in the following modes: ion scanning, continuously sweeping the mass spectrum; monitoring of a selected ion(s), passing ions in a selected narrow mass range / passing ions, sequentially switching between selected narrow mass ranges; ion transport, transporting ions over a wide mass range. Upon leaving the first quadrupole mass filter with radio frequency segment 35, ions enter the hexapole-based collision cell 36.

[0016] The hexapole collision cell 36 can operate in both transport and fragmentation modes. In transport mode, the hexapole collision cell is not supplied with pure nitrogen, and it functions as a radiofrequency ion guide. In fragmentation mode, the hexapole collision cell is filled with pure nitrogen, causing incoming ions to collide with gas molecules and fragment. The molecular ions or product ions of the fragmentation reaction exit the hexapole collision cell 36 and enter the second quadrupole mass filter with radiofrequency segment 37.

[0017] The second quadrupole mass filter with a 37-segment radio frequency can operate in the following modes: ion scanning, continuously sweeping the mass spectrum; monitoring of a selected ion / ions, passing ions in the selected mass range / passing ions, sequentially switching between the selected mass ranges.

[0018] The ions that have passed the second quadrupole mass filter with radio frequency segment 37 enter the charged particle detector 38 and form an analytical signal that allows the molecular composition of the sample to be determined.

Claims

A tandem triple-quadrupole mass spectrometer comprising a housing, an analytical system, a vacuum system, characterized in that the vacuum system is made in the form of a monolithic vacuum chamber with a lid secured by screwing, containing three cavity sections, wherein the first cavity section of the vacuum chamber is connected by screwing through a vacuum hose and fittings to the first forevacuum pump with a capacity of 40-80 m 3 / h, the second cavity-section of the vacuum chamber is pumped out by the first turbomolecular pump with a capacity of 260-300 l / s, the rotor axis of which is located orthogonally to the optical axis of the transport hexapole, the third cavity-section is pumped out by the second turbomolecular pump with a capacity of 390-500 l / s, the rotor axis of which is located parallel to the optical axis of the system of quadrupole mass filters with radio frequency segments, and the second turbomolecular pump is secured by screwing on the wall closest to the charged particle detector in the area of ​​the third cavity-section of the vacuum chamber, perpendicular to the axis of the ion-optical system, and a second forevacuum pump with a capacity of 40-80 m is connected to the outlet of both turbomolecular pumps through a vacuum hose and fittings by screwing 3 / h, while the analytical system includes a resistive transport capillary, a skimmer and a transport hexapole, ensuring high sensitivity.

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