Control method for reducing mass number interference in triple quadrupole mass spectrometry

Abstract

The application discloses a control method for reducing mass number interference in a triple quadrupole mass spectrometer, relates to the technical field of triple quadrupole mass spectrometry, and is applied to a triple quadrupole mass spectrometer, wherein the triple quadrupole mass spectrometer comprises a mass filter for screening parent ions, a collision chamber, a mass analyzer for screening daughter ions, a detector and an ion source; a pre-focusing rod PQ1 is arranged at the front end of the mass filter, and a pre-focusing rod PQ3 is arranged at the front end of the mass analyzer; the pre-focusing function of the pre-focusing rod PQ1 and the pre-focusing rod PQ3 is started in each scanning period; in the interval period between two scanning periods, the pre-focusing function of the pre-focusing rod PQ1 and the pre-focusing rod PQ3 is stopped, so that residual ions in the interval period are removed at the pre-focusing rod PQ1 and the pre-focusing rod PQ3, and the mutual influence of mass number scanning between different periods is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of triple quadrupole mass spectrometry, and in particular to a control method for reducing mass number interference in a triple quadrupole mass spectrometry. Background Art

[0002] Triple quadrupole mass spectrometry is a highly sensitive and selective mass spectrometry technology that is widely used in the qualitative and quantitative analysis of trace compounds in complex matrices.

[0003] Each mass number has a fixed scanning time. Since it takes a certain amount of time for the sample to be measured to be guided from the ion source to the detector, in the mass spectrometry method, the mass number scan of the previous section will affect the mass number scan of the next section. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art. To this end, one object of the present invention is to provide a control method for reducing mass number interference in a triple quadrupole mass spectrometer, thereby reducing the mutual influence of mass number scans between different time periods.

[0005] According to a first aspect of an embodiment of the present invention, a control method for reducing mass number interference in a triple quadrupole mass spectrometer is provided, which is applied to a triple quadrupole mass spectrometer, wherein the triple quadrupole mass spectrometer includes a mass filter for screening parent ions, a collision cell, a mass analyzer for screening daughter ions, a detector, and an ion source; the ion source, the mass filter, the collision cell, the mass analyzer, and the detector are connected in sequence;

[0006] The front end of the mass filter is provided with a pre-focusing rod PQ1, and the front end of the mass analyzer is provided with a pre-focusing rod PQ3;

[0007] The control method includes:

[0008] Turning on the prefocusing function of the prefocusing rod PQ1 and the prefocusing rod PQ3 in each scanning period;

[0009] In an interval between two scanning periods, the prefocusing functions of the prefocusing rod PQ1 and the prefocusing rod PQ3 are stopped, so that residual ions in the prefocusing rod PQ1 and the prefocusing rod PQ3 are cleared in the interval.

[0010] Optionally, the prefocusing function is stopped by controlling the voltages of the prefocusing rod PQ1 and the prefocusing rod PQ3.

[0011] Optionally, the method of stopping the prefocusing function of the prefocusing rod PQ1 and the prefocusing rod PQ3 includes:

[0012] The prefocus lever PQ1 and the prefocus lever PQ3 are grounded.

[0013] Optionally, the voltage control is performed by controlling DAC via FPGA.

[0014] Optionally, lenses are provided at the front ends of the pre-focusing rod PQ1, the collision chamber, and the pre-focusing rod PQ3.

[0015] Optionally, the control method further includes:

[0016] During the interval, the potential difference between the front lens FL2 of the collision cell and the collision cell is controlled to reduce the acceleration effect on the ions.

[0017] Optionally, controlling the potential difference between the front lens FL2 of the collision cell and the collision cell to reduce the acceleration effect on ions includes:

[0018] The front lens FL2 is brought to the same potential as the collision cell.

[0019] Optionally, in each scanning period, a deceleration electric field is provided before the mass analyzer and the mass filter.

[0020] Optionally, the triple quadrupole mass spectrometer further includes a guiding device arranged before the pre-focusing rod PQ1.

[0021] Optionally, in each scanning period, multiple accelerating electric fields are set in the triple quadrupole mass spectrometer.

[0022] Optionally, a lens EC is provided before the detector.

[0023] According to a second aspect of an embodiment of the present invention, a triple quadrupole mass spectrometer is provided, comprising a mass filter for screening parent ions, a collision cell, a mass analyzer for screening daughter ions, a detector, and an ion source; the ion source, the mass filter, the collision cell, the mass analyzer, and the detector are connected in sequence;

[0024] The front end of the mass filter is provided with a pre-focusing rod PQ1, and the front end of the mass analyzer is provided with a pre-focusing rod PQ3;

[0025] The triple quadrupole mass spectrometer performs mass number scanning using any of the above-mentioned control methods for reducing mass number interference in triple quadrupole mass spectrometry.

[0026] As can be seen from the above, by controlling the pre-focusing function of the pre-focusing rods PQ1 and PQ3 to be stopped, the ions remaining in the last scan period can be neutralized at the pre-focusing rods PQ1 and PQ3 in the interval period between two scan periods, so that the remaining ions are emptied, and thus the mass number scan of the next scan period will not be affected by the remaining ions. Therefore, by removing the remaining ions in the interval period between each two scan periods, the mutual influence of the mass number scans between different periods can be reduced.

[0027] Additional aspects and advantages of the present application will be set forth in part in the description that follows, and in part will become apparent to those having ordinary skill in the art upon examination of the following or can be learned from practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a flowchart of a control method for reducing mass number interference in a triple quadrupole mass spectrometer provided by an embodiment of the present application;

[0029] Figure 2 is a structural schematic diagram of a triple quadrupole mass spectrometer provided by an embodiment of the present application;

[0030] Figure 3 is a timing diagram of voltage control provided by an embodiment of the present application. DETAILED DESCRIPTION

[0031] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, in which the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0032] In one embodiment of the present application, referring to Figure 1 , a control method for reducing mass number interference in a triple quadrupole mass spectrometer is provided, which is applied to a triple quadrupole mass spectrometer, and includes a mass filter for screening parent ions, a collision chamber, a mass analyzer for screening daughter ions, a detector, and an ion source; the ion source, the mass filter, the collision chamber, the mass analyzer, and the detector are connected in sequence.

[0033] A pre-focusing rod PQ1 is arranged at the front end of the mass filter, and a pre-focusing rod PQ3 is arranged at the front end of the mass analyzer,

[0034] The control method includes:

[0035] S101: Turn on the pre-focusing function of the pre-focusing rods PQ1 and PQ3 in each scan period;

[0036] S102: In an interval between two scanning periods, the prefocusing function of the prefocusing rod PQ1 and the prefocusing rod PQ3 is stopped, so that residual ions in the interval are cleared at the prefocusing rod PQ1 and the prefocusing rod PQ3.

[0037] The mass filter is used to screen specific parent ions; the collision chamber is used to allow the parent ions to collide with inert gases such as nitrogen and fragment into daughter ions; and the mass analyzer is used to perform mass analysis or scanning on the daughter ions.

[0038] Here, the “front end” refers to the ion source of the triple quadrupole mass spectrometer. Figure 2 As shown, ORV represents the ion source, and "front end" means that the pre-focusing rod PQ1 is closer to the ion source ORV than the mass filter Q1. Similarly, the pre-focusing rod PQ3 is closer to the ion source ORV than the mass analyzer Q3.

[0039] The mass filter Q1, pre-focusing rods PQ1, PQ2, PQ3, mass analyzer Q3, and collision cell Q2 are all composed of quadrupole rods.

[0040] In one embodiment of the present invention, Figure 2 As shown, the front ends of the pre-focusing rod PQ1, collision cell, and pre-focusing rod PQ3 are all equipped with lenses, including FL0, FL1, FL2, and FL3. When ions pass through each lens, they can be more focused, allowing them to pass stably through various components such as the mass filter and collision cell.

[0041] Because the focal length of the lens is short, ions expand and diverge after passing through it. To prevent ion divergence during the scanning period, a gradient field is applied to the prefocusing rods PQ1 and PQ3. This slowly changes the electric field and reduces the expansion, thus achieving prefocusing.

[0042] exist Figure 2 In the figure, CEM represents the detector. During each scan period, multiple accelerating electric fields are set in the triple quadrupole mass spectrometer.

[0043] Figure 2 The arrow in the figure indicates the direction of the electric field. The arrow pointing to the CEM direction indicates the accelerating electric field. Thus, the ions can be accelerated by the potential difference, the ion guidance is enhanced, and the ions quickly reach the detector CEM to realize mass number detection.

[0044] Among them, for a triple quadrupole mass spectrometer, mass number detection is not limited to being performed once, but ions are re-emitted through the ion source ORV at different scanning periods to perform scanning, as shown in Table 1 below, taking the MRM (Multiple Reaction Monitoring) mode as an example.

[0045] Table 1

[0046]

[0047] Among them, each serial number represents a scan, and different scans are performed in different scanning periods. T1, T2, and T3 in the scanning time (ms) represent the duration of the scanning period. M11, M21, and M31 in the Q1 mass (Da) are the masses of the parent ions detected in each scanning period. M12, M22, and M32 in the Q3 mass (Da) are the masses of the daughter ions detected in each scanning period.

[0048] In order to reduce the influence of the residual mass number in the previous scanning period on the mass number detection result in the next scanning period between two scanning periods, step S102 adds an interval period between the two scanning periods to clear the residual mass number in the previous scanning period.

[0049] The prefocusing function is stopped by controlling the voltage of the prefocus levers PQ1 and PQ3, wherein the voltage control is performed by controlling the DAC via the FPGA.

[0050] During the interval, the remaining ions from the previous scan period, after ceasing the focusing interaction, decelerate and move toward PQ1 and PQ3 until they reach PQ1 and PQ3. A voltage less than a preset threshold, such as 0V or 0.1V, is applied to PQ1 and PQ3. Because the ion charge is neutralized, it stops moving, effectively clearing the remaining ions.

[0051] In another embodiment, the method of stopping the prefocusing function of the prefocusing rod PQ1 and the prefocusing rod PQ3 includes:

[0052] The pre-focusing rods PQ1 and PQ3 are grounded. This method can also neutralize the ion charge, and the voltage control method is simple and easy to implement.

[0053] As can be seen from the above, by controlling the prefocusing action of the prefocusing rods PQ1 and PQ3 to stop, the ions remaining in the previous scanning period can be controlled to be neutralized at the prefocusing rods PQ1 and PQ3 in the interval between two scanning periods, thereby clearing the residual ions. In this way, the mass number scan in the next scanning period will not be affected by the residual ions. Therefore, by clearing the residual ions in the interval between each two scanning periods, the mutual influence of the mass number scans between different periods can be reduced.

[0054] During the interval, the potential difference between the front lens FL2 of the collision cell and the collision cell is controlled to reduce the acceleration effect on the ions.

[0055] Figure 2In the embodiment, specifically, during the interval period, the front lens FL2 and the collision chamber can be made to have the same potential. This voltage control method is simple and easy to implement.

[0056] The voltage of the third lens can be controlled by the DAC (Digital-to-Analog Converter) output by the FPGA (Field-Programmable Gate Array) on the lens circuit board.

[0057] Figure 2 In an embodiment, an accelerating electric field may be set between the third lens FL2 and the collision chamber Q2 during each scanning period.

[0058] During the scanning period, the electric field formed between the third lens FL2 and the collision chamber Q2 is equivalent to increasing the kinetic energy of the ions so that sufficient collisions occur in the collision chamber Q2. During the interval period, the potential difference is controlled to decrease or be equal, such as setting the third lens FL2 to the same potential as the collision chamber Q2, which does not increase the kinetic energy of the ions and facilitates the removal of residual ions.

[0059] In each scanning period, a deceleration electric field is set before the mass analyzer and mass filter.

[0060] Figure 2 In an embodiment, in each scanning period, the deceleration electric field is represented by an arrow pointing to the ion source ORV, and the deceleration electric field can be set to have a potential difference less than a threshold value, which can appropriately reduce the ion kinetic energy deceleration, thereby appropriately increasing the analysis time of the mass analyzer and mass filter, making the results of the ion analysis more accurate.

[0061] In one embodiment of the present invention, the triple quadrupole mass spectrometer further comprises a guiding device arranged before the pre-focusing rod PQ1. Figure 2 In the embodiment, the guiding device includes pre-focusing rods Q0 and QIG and lens FL0, which are similar to the pre-focusing rods in the above-mentioned embodiments and can improve the focusing guiding effect before entering the mass filter.

[0062] in addition, Figure 2 In the example, a lens EC is placed before the detector. The multi-stage lens arrangement can enhance the focusing effect of each stage, making it easier for the detector to detect.

[0063] In one embodiment of the present invention, a triple quadrupole mass spectrometer is further provided, comprising a mass filter for selecting parent ions, a collision cell, a mass analyzer for scanning daughter ions, a detector, and an ion source; the ion source, the mass filter, the collision cell, the mass analyzer, and the detector are connected in sequence;

[0064] The front end of the mass filter is provided with a pre-focusing rod PQ1, and the front end of the mass analyzer is provided with a pre-focusing rod PQ;

[0065] The triple quadrupole mass spectrometer performs mass number scanning using the control method for reducing mass number interference in a triple quadrupole mass spectrometer according to any of the above embodiments.

[0066] like Figure 3 As shown, in the above scheme, a voltage adjustment is performed in each interval period, the voltage of the prefocusing rod PQ1 and the prefocusing rod PQ3 is set to 0V, and the voltage of the third lens FL2 is set to the same voltage as the collision chamber Q2. After a residual ion removal process, the voltage is restored in the next scanning period, and the voltage values ​​of PQ1, FL2, and PQ3 are restored to PQ1-N, FL2-N, and PQ3-N, respectively, where N is 1, 2, 3, ..., and each value of N corresponds to a scanning period.

[0067] It should be understood that various components of the present invention may be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods may be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof may be used: a discrete logic circuit having logic gate circuits for implementing logic functions on data signals, an application-specific integrated circuit having suitable combinational logic gate circuits, a programmable gate array (PGA), a field-programmable gate array (FPGA), etc.

[0068] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0069] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0070] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0071] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0072] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0073] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A control method for reducing mass number interference in triple quadrupole mass spectrometry, characterized in that: Applied to a triple quadrupole mass spectrometer, the triple quadrupole mass spectrometer comprises a mass filter for screening parent ions, a collision cell, a mass analyzer for screening daughter ions, a detector, and an ion source; the ion source, the mass filter, the collision cell, the mass analyzer, and the detector are connected in sequence; The front end of the mass filter is provided with a pre-focusing rod PQ1, and the front end of the mass analyzer is provided with a pre-focusing rod PQ3; The control method includes: Turning on the prefocusing function of the prefocusing rod PQ1 and the prefocusing rod PQ3 in each scanning period; In an interval between two scanning periods, the prefocusing functions of the prefocusing rod PQ1 and the prefocusing rod PQ3 are stopped, so that residual ions in the prefocusing rod PQ1 and the prefocusing rod PQ3 are cleared in the interval.

2. The method according to claim 1, characterized in that The prefocusing function is stopped by controlling the voltages of the prefocusing lever PQ1 and the prefocusing lever PQ3.

3. The method according to claim 1, characterized in that The method of stopping the prefocusing function of the prefocusing rod PQ1 and the prefocusing rod PQ3 includes: The prefocus lever PQ1 and the prefocus lever PQ3 are grounded.

4. The method according to claim 2, characterized in that The voltage control is performed by controlling the DAC through the FPGA.

5. The method according to claim 1, wherein The front ends of the pre-focusing rod PQ1, the collision chamber, and the pre-focusing rod PQ3 are all provided with lenses.

6. The method according to claim 5, characterized in that The control method further includes: During the interval, the potential difference between the front lens FL2 of the collision cell and the collision cell is controlled to reduce the acceleration effect on the ions.

7. The method according to claim 6, characterized in that The controlling the potential difference between the front lens FL2 of the collision cell and the collision cell to reduce the acceleration effect on ions includes: The front lens FL2 is brought to the same potential as the collision cell.

8. The method according to claim 1, characterized in that In each scanning period, a deceleration electric field is provided before the mass analyzer and the mass filter.

9. The method according to claim 1, characterized in that The triple quadrupole mass spectrometer further includes a guiding device arranged before the pre-focusing rod PQ1.

10. The method according to claim 1, characterized in that In each scanning period, a plurality of accelerating electric fields are set in the triple quadrupole mass spectrometer.

11. The method according to claim 1, wherein The detector is preceded by a lens EC.

12. A triple quadrupole mass spectrometer, characterized in that The triple quadrupole mass spectrometer comprises a mass filter for screening parent ions, a collision cell, a mass analyzer for screening daughter ions, a detector, and an ion source; the ion source, the mass filter, the collision cell, the mass analyzer, and the detector are connected in sequence; The front end of the mass filter is provided with a pre-focusing rod PQ1, and the front end of the mass analyzer is provided with a pre-focusing rod PQ3; The triple quadrupole mass spectrometer performs mass number scanning using the control method for reducing mass number interference in a triple quadrupole mass spectrometer according to any one of claims 1 to 9.

Images