Rotary collision reaction tank of inductively coupled plasma mass spectrometer

Abstract

The utility model relates to the technical field of inductively coupled plasma mass spectrometers, in particular to a rotary collision reaction tank of an inductively coupled plasma mass spectrometer, which comprises a shell and a multi-pole rod ion guider, and is characterized in that the shell comprises a tank inlet, a tank outlet and a gas supply port communicated with the internal structure of the shell; a multi-pole rod ion guide is disposed inside the housing along a longitudinal axis of the housing, the multi-pole rod ion guide configured to generate an RF confinement field effective to constrain ions in a radial direction orthogonal to the longitudinal axis of the housing, the multi-pole rod ion guide comprising a plurality of elongate rod electrodes, the multiple rod electrodes are arranged in a rotary structure around the longitudinal axis of the shell so as to generate certain torsion on ions entering the rod electrodes and enable the ion beams to rotate and compress according to a set angle while moving forwards in an oscillating mode. According to the utility model, the ions can move spirally, so that the mutual collision among the ions is reduced, and the ion transmission efficiency in a collision mode is greatly improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to inductance coupling plasma mass spectrometer technical field especially relates to a kind of rotary collision reaction cell of inductance coupling plasma mass spectrometer. BACKGROUND

[0002] Inductively coupled plasma mass spectrometer (ICP-MS) systems include a plasma-based ion source for generating a plasma to decompose molecules of a sample into atoms, and then ionize the atoms in preparation for elemental analysis. In typical operation, a liquid sample is nebulized, i.e., converted into an aerosol (fine spray or mist), by a gas-driven (typically argon) nebulizer, and the coarse aerosol is removed within a nebulization chamber, and the remaining fine aerosol is directed into a plasma generated by a plasma source. The plasma source is often configured as a flow-through plasma torch tube having two or more concentric tubes, typically, a plasma-forming gas (argon) flows through the inner tube of the torch tube and is excited into a plasma by a suitable energy source, such as a radio frequency (RF) powered load coil. The aerosol flows through the coaxial center tube of the torch tube and is emitted into the generated plasma, exposure to the plasma decomposes the sample molecules into atoms, or alternatively, partially decomposes the sample molecules into molecular fragments and ionizes the atoms or molecular fragments.

[0003] The produced analyte ions, which are typically positively charged, are extracted from the plasma ion source and directed as an ion beam to a mass analyzer, which is typically of a quadrupole rod structure, or other such as a sector magnetic field, time of flight (TOF) analyzer, etc., applies alternating electric fields, or a combination of electric and magnetic fields, to spectrally resolve the ionized ions according to their mass-to-charge ratio (m / z), and then enables an ion detector to count each type of ion of a given m / z ratio that reaches the ion detector from the mass analyzer, the intensity of each peak indicates the concentration or abundance of the corresponding element of the sample.

[0004] As a plasma ion source for ICP-MS, in addition to generating analyte ions, certain interfering ions are also produced that interfere with the analysis of certain types of analytes. Interfering ions can be produced from the plasma forming gas (e.g., argon), matrix components of the sample, solvents / acid included in the sample, or air (oxygen and nitrogen) entrained into the system. For example, interfering ions can be isobaric interferences that have the same nominal mass as the analyte ions. Detection of these interfering ions, as well as certain analyte ions, results in spectral overlap in the analytical data, thereby degrading the quality of the analysis. Examples of interfering ions include polyatomic ions such as argon oxide 40Ar35Cl+and argon 40Ar+, which interfere with the iron isotope 75As+because both ions appear at m / z = 75 in the mass spectrum, and which interfere with the calcium isotope 40Ca+because both ions appear at m / z = 40.

[0005] Known methods for resolving spectral interferences and improving the performance of ICP-MS systems include performing matrix separation, using cold plasma techniques, and using numerical deconvolution equations when processing the analytical data, all of which have known limitations. To further address the problem of interfering ions, it is known to provide a collision / reaction cell between the ion source and the mass analyzer in an ICP-MS system. Today's mainstream products are equipped with a collision / reaction cell that contains a multipole rod inside the cell. The collision / reaction cell is filled with a collision gas or a reaction gas. The use of a collision gas (e.g., helium) relies on kinetic energy discrimination (KED) by which polyatomic ion interferences can be suppressed. Analyte ions and polyatomic interfering ions in the cell experience multiple collisions with the collision gas and lose kinetic energy (KE) and thus slow down. However, because the interfering polyatomic ions have a larger cross section than the analyte ions, the polyatomic interfering ions experience more collisions and thus lose more kinetic energy than the analyte ions. Thus, kinetic energy discrimination (KED) can be utilized to separate the analyte ions from the polyatomic interfering ions.

[0006] In a conventional multipole collision / reaction cell, after the ion beam is focused by an entrance ion lens, the ion beam enters the cell body through the front-end small hole of the collision reaction cell, and under the action of the multipole radio frequency, the ion will oscillate between the poles perpendicular to the axial direction while moving forward along the axial direction, thereby forming a spiral trajectory. The trajectory of the ion will inevitably be constantly changed in the process of moving forward due to the collision between the ion and the gas molecules in the cell body and the thermalization effect of the ion. However, in the existing multipole collision / reaction cell, each pole is in a straight line structure and is arranged in parallel, and the radio frequency signal applied to the pole can only make the ion oscillate in a direction perpendicular to the axial direction of the collision / reaction cell, so as to cause the running trajectory of the ion to be chaotic, thereby causing the mutual collision between the ions. Since the mass of the ion is much higher than that of the collision gas (generally helium), the mutual collision between the ions will cause the analyte ions to lose too much kinetic energy instantaneously, so as to be unable to cross the subsequent DC potential barrier. Therefore, when the KED mode is used in the current multipole collision / reaction cell, more than 70% of the sensitivity will be lost under the premise of ensuring a certain intensity ratio of the analyte ions to the interfering ions.

[0007] The prior art such as Chinese Patent CN103890901B improves the sensitivity of the instrument by adopting a plurality of multipole rods or curved multipole rods in the improved ion inlet end cross section, so that more ions can be introduced into the collision reaction cell. However, the technology has the following problems: 1. The technology also adopts a parallel multipole rod design, which cannot effectively reduce the mutual collision between particles and cannot improve the collision reaction efficiency of the ions, like the existing mature collision reaction cell; 2. Since the multipole rods in the collision reaction cell need to be processed and assembled with very high precision, the technology design is complex and difficult to implement in processing and assembly, which will bring high costs.

[0008] Therefore, an improved collision / reaction cell is needed to control the oscillation rotation direction of the ions in the cell, so as to reduce the mutual collision between the ions and improve the collision reaction efficiency, so as to better solve the interference problem. Content of the utility model

[0009] The technical problem to be solved by the utility model is how to reduce the mutual collision between the ions in the collision reaction cell and improve the ion transmission efficiency.

[0010] In order to solve the above technical problem, the utility model provides a rotating collision / reaction cell of an inductively coupled plasma mass spectrometer, which comprises:

[0011] A shell, the shell comprises a cell inlet, a cell outlet arranged opposite to the cell inlet along a longitudinal axis of the shell, and a gas supply port in communication with an internal structure of the shell; and

[0012] a multipole rod ion guide disposed inside the housing along a longitudinal axis of the housing, the multipole rod ion guide configured to generate an RF trapping field for ions trapped effectively in a radial direction orthogonal to the longitudinal axis of the housing;

[0013] The multipole rod ion guide comprises a plurality of elongated rod electrodes arranged to impart a certain torsion to ions entering the multipole rod ion guide and to rotate and compress the ions at a set angle while oscillating forward.

[0014] Further preferably, the plurality of rod electrodes are located at a predetermined radial distance from the longitudinal axis of the housing, are circumferentially spaced apart from each other around the longitudinal axis, and define an inlet and an outlet of the multipole rod ion guide.

[0015] Further preferably, the field radius of the inlet end of the multipole rod ion guide is greater than that of the outlet end; or

[0016] The field radius of the inlet end of the multipole rod ion guide is less than that of the outlet end.

[0017] Further preferably, one set of the rod electrodes is configured to apply an RF+ potential superimposed on a DC bias potential (U), and another set of the rod electrodes is configured to apply an RF- potential superimposed on the DC bias potential (U).

[0018] Wherein, RF+ and RF- are radio frequency signals of the same frequency and amplitude but opposite phase, the frequency being 1-20 MHZ, thereby generating an RF trapping field for ions.

[0019] Further preferably, the RF trapping field generated in the multipole rod ion guide is for ions trapped in a radial direction orthogonal to the longitudinal axis, and a negative DC potential barrier is generated at the outlet of the multipole rod ion guide so that ions can be smoothly guided out of the collision / reaction cell.

[0020] Further preferably, the number of rod electrodes is 2N (N is an integer and N≥2).

[0021] Further preferably, the rotation angle of the rod electrodes at both ends is θ, where 0°<θ<360°.

[0022] Further preferably, the rod electrodes are one of a round rod, a square rod, a hyperboloid rod, or a concave rod.

[0023] Further preferably, it further comprises:

[0024] an inlet ion mirror disposed on the cell inlet side of the housing; and

[0025] An exit ion mirror is arranged at the pool exit side of the housing.

[0026] The rotating collision / reaction pool of the inductively coupled plasma mass spectrometer has the advantages that:

[0027] The plurality of rod electrodes arranged in a rotating structure around the longitudinal axis of the housing are combined into a multipole rod ion guide, and the rotating structure is adopted, so that a certain torsion is generated on the ion beam entering the guide, the ion beam is rotated and compressed at a set angle while oscillating forward, so that the ions perform spiral motion in the collision / reaction pool according to the rotating direction of the rod electrodes, the mutual collision between the ions is reduced, the rapid decay of the kinetic energy of the to-be-measured ions is inhibited, and the ion transmission efficiency under the collision mode is greatly improved; in addition, since the multipole rod ion guide arranged in a rotating manner is adopted, the initial axial kinetic energy is provided for the ions, and at the same time, the rotating kinetic energy consistent with the rotating direction of the multipole rod ion is continuously provided, so that the initial kinetic energy of the ions is improved, and the generation of zero kinetic energy ions is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is an explosion schematic view of the rotating collision / reaction pool of the inductively coupled plasma mass spectrometer.

[0029] Figure 2 is an assembly simplified view of the housing and the multipole rod ion guide.

[0030] Figure 3 is a structural schematic view of the rod electrode.

[0031] Figure 4 is a side view of the rod electrode.

[0032] Figure 5 is a circuit demonstration view of the rod electrode.

[0033] In the figure:

[0034] 10, housing; 101, pool inlet; 102, pool outlet; 103, gas supply port;

[0035] 20, multipole rod ion guide; 201, rod electrode;

[0036] 30, inlet ion mirror;

[0037] 40, exit ion mirror.

[0038] 50, fixed ring;

[0039] 60, insulating gasket;

[0040] 70. RF+ connection electrode;

[0041] 80. RF - Connecting electrode;

[0042] 90. Resistance. Detailed Implementation

[0043] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.

[0044] In the description of this utility model, it should be understood that the terms "longitudinal", "radial", "orthogonal", "opposite", "one end", "the other end", etc., used in this utility model to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0045] The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of these terms in this utility model based on the specific circumstances.

[0046] like Figures 1-5 As shown, this embodiment provides a rotating collision reaction cell for an inductively coupled plasma mass spectrometer, including a housing 10, a multipole ion guide 20, an inlet ion mirror 30, and an outlet ion mirror 40. The multipole ion guide 20 is disposed inside the housing 10 along the longitudinal axis of the housing 10, and the multipole ion guide 20 is connected to the housing 10 by a fixing ring 50.

[0047] In a specific example, the housing 10 includes a pool inlet 101, a pool outlet 102 disposed opposite to the pool inlet 101 along the longitudinal axis of the housing 10, and a gas supply port 103 communicating with the internal structure of the housing 10. The inlet ion mirror 30 is disposed on the pool inlet 101 side of the housing 10, and the outlet ion mirror 40 is disposed on the pool outlet 102 side of the housing 10.

[0048] The multipole rod ion guide 20 is configured to generate an RF confinement field that effectively confines ions in a radial direction that is orthogonal to the longitudinal axis of the housing 10. The multipole rod ion guide 20 includes a plurality of elongated rod electrodes 201 arranged in a rotational structure around the longitudinal axis of the housing 10 to generate a certain torsion force on the ions entering the rod electrodes 201 and make the ion beam oscillate forward while rotating and compressing at a set angle. The plurality of rod electrodes 201 are arranged in a rotational structure to generate a certain torsion force on the ion beam entering the multipole rod ion guide 20, so that the ion beam oscillates forward while rotating and compressing at a set angle, so that the ions perform helical motion in the collision / reaction cell according to the rotation direction of the rod electrodes 201, thereby reducing the mutual collision between the ions, suppressing the rapid decay of the kinetic energy of the ions to be tested, and greatly improving the ion transmission efficiency in the collision mode. In addition, since the multipole rod ion guide 20 is arranged in a rotational structure, the initial axial kinetic energy of the ions is continuously provided to the ions in the same direction as the rotation direction of the plurality of rod electrodes 201, thereby increasing the initial kinetic energy of the ions and greatly reducing the generation of zero kinetic energy ions.

[0049] In the above examples, the longitudinal axis refers to the axis of the housing 10 in the length direction.

[0050] In the above examples, the number of rod electrodes 201 is 2N (N is an integer and N≥2), and preferably the multipole rod ion guide 20 can be a quadrupole rod, a hexapole rod, an octapole rod, a decapole rod, a dodecapole rod, etc.

[0051] In some embodiments, each rod electrode 201 is arranged at a certain inclination angle, and the rotation angle of the rod electrode 201 is θ, where 0°<θ<360°. The rotation angle refers to that one end of the rod electrode 201 is fixed, and the other end rotates around the longitudinal axis by a certain angle, so that the rod electrode 201 forms a rotational structure with an inclination angle.

[0052] In some embodiments, the plurality of rod electrodes 201 are located at a predetermined radial distance from the longitudinal axis of the housing 10, and are circumferentially spaced apart from each other around the longitudinal axis, and define an inlet and an outlet of the multipole rod ion guide 20. The inlet of the multipole rod ion guide 20 corresponds to the cell inlet 101, and the outlet of the multipole rod ion guide 20 corresponds to the cell outlet 102.

[0053] In some embodiments, the field radius of the inlet end of the multipole rod ion guide 20 is greater than the field radius of the outlet end, or the field radius of the inlet end of the multipole rod ion guide 20 is less than the field radius of the outlet end. The field radius refers to the diameter of the inscribed circle in the multipole rod.

[0054] In some embodiments, asFigure 5 As shown, the rod electrodes 201 are divided into two groups by spacing, wherein one group of the rod electrodes 201 spaced apart is configured to apply RF+ potential superimposed on DC bias potential (U), specifically, the group of the rod electrodes 201 is connected with the RF+ connecting electrode 70; the other group of the rod electrodes 201 spaced apart is configured to apply RF- potential superimposed on DC bias potential (U), specifically, the group of the rod electrodes 201 is connected with the RF- connecting electrode 80. A direct current bias (U) can be superimposed on these rod electrodes 201 through one or a group of resistors 90, so as to adjust the kinetic energy of ions in the collision / reaction cell, such as Figure 5 As shown.

[0055] In the above example, RF+ and RF- are radio frequency signals with same frequency and amplitude and opposite phase (180° difference), the frequency is 1-20 MHz, so as to generate RF confinement field for ions. In this way, the ions oscillate and rotate forward while colliding with the gas in the collision / reaction cell. The interfering ions encounter more collisions due to larger cross-sectional area, so as to lose more kinetic energy and thus cannot cross the subsequent direct current voltage barrier; the ions of the element to be tested encounter fewer collisions due to smaller cross-sectional area, although part of the kinetic energy is lost, but still can cross the subsequent direct current voltage barrier, so as to realize the separation of the interfering ions and the ions of the element to be tested.

[0056] In some embodiments, the RF confinement field generated in the multipole rod ion guide 20 is used to confine the ions in the radial direction orthogonal to the longitudinal axis, and a negative DC potential barrier is generated at the outlet of the multipole rod ion guide 20, so as to smoothly guide the ions out of the collision / reaction cell.

[0057] In some embodiments, the rod electrodes 201 are one of circular rod, square rod, hyperboloid rod or concave rod.

[0058] In some embodiments, the shell 10 is preferably processed from metal material, and has corresponding structures inside for fixing the rod electrodes, and is provided with insulating gaskets 60 at both ends for fixing the inlet ion mirror 30 and the outlet ion mirror 40, and has a gas supply port 103 in the middle for the collision or reaction gas to enter the inside of the shell 10, and the middle of the inside of the shell 10 is provided with a device for fixing the multipole rod ion guide 20.

[0059] In the above example, the outer end of the gas supply port 103 is connected with a device for controlling the gas flow (such as a mass flow meter) and a switch (such as an electromagnetic valve) for selecting the type of gas, and the control range of the gas flow is 0-20 milliliters per minute.

[0060] In some embodiments, the inlet ion mirror 30 and outlet ion mirror 40 of the collision / reaction cell are made of metal and have a circular hole in the middle for ions to enter and exit, with a diameter of 1-10 mm. A negative DC voltage is applied to the lens to guide ions into and out of the collision reaction cell.

[0061] In this embodiment, the multipole ion guide 20 adopts a rotating arrangement. Compared with the parallel arrangement of multipoles, it applies a certain rotational potential energy to the ions while they oscillate in the direction perpendicular to the axis. This causes the ions to oscillate and move forward in the collision / reaction cell in the direction of multipole rotation, which greatly reduces the collisions between ions and thus suppresses the rapid decay of the kinetic energy of the ions to be measured.

[0062] This embodiment improves sensitivity in kinetic energy discrimination (KED) mode. The effectiveness of this embodiment is demonstrated below by calculating the kinetic energies of the analyte ions and interfering ions.

[0063] Two ionic substances, A (an atomic analyte ion) and B (a polyatomic ion interfering with A), are considered. Ion B has the same mass or m / z ratio as ion A, but is larger. It is assumed that ion B collides with gas molecules more than twice as frequently as ion A due to its larger size (larger collision cross-sectional area).

[0064] At the entrance of the collision cell, A and B ions have the same initial kinetic energy E given by the instrument operating conditions. i Initial kinetic energy E i Typically, it is around 20 eV. In the collision cell, both A and B ions gradually decelerate each time they collide with the colliding gas molecules. In the hard-sphere collision model, the final kinetic energy (the kinetic energy possessed by the ion at the exit of the collision cell) is approximately given by the following equation:

[0065]

[0066] Where m1 and m2 are the masses of the ion and gas molecule, respectively, and N is the number of collisions the ion experiences in the collision cell; E i This is the initial kinetic energy.

[0067] Because the average nitrogen (N) of B ions is greater than that of A ions, the energy (E) of B ions is... f E smaller than A ion f .

[0068] For example, calculate A = 75As according to the above formula. + Ions (m1 = 75u) collided 15 times with helium gas (m2 = 4u) and B = 40Ar35Cl + The approximate final energy E of the ion (m1 = 75u) colliding with the helium gas 30 times. f / A and Ef / B, as follows:

[0069] E f / A = 0.22E i , and

[0070] E f / B = 0.048E i ,

[0071] When E i = 21-25 eV, E f / A = 4.6-5.5 eV and E f / B = 1.0-1.2 eV.

[0072] Thus, by setting a 3 eV high potential barrier after the collision cell, low energy B ions are blocked by the barrier while higher energy A ions can pass over the barrier. In this way, analyte ions A are selectively detected while interfering ions B are removed from the ion beam after the barrier. This technique is known as kinetic energy discrimination (KED), as described elsewhere herein. Since the flow rate of the collision gas into the collision / reaction cell is adjustable, the collision gas flow rate can be optimized by observing the ratio of the signal intensity of the ions to be measured to the signal intensity of the interfering ions at a certain concentration.

[0073] As previously described, the multipole ion guides of a typical collision / reaction cell are uniformly divided between the poles and arranged in parallel, so that when the ion beam enters the cell, the radio frequency on the multipole only produces oscillation perpendicular to the axis of the cell for the entering ion beam, and the spiral direction of the ions is not controlled. When there is no collision gas in the collision / reaction cell, the running speed of these ions is basically uniform, so the collision opportunity between them is very small. However, when a certain flow rate of collision gas (generally 3-8 ml / min of helium) is introduced into the collision cell, the gas molecules continuously collide with the ions in the ion beam, causing the running direction, speed and trajectory of the ions to change. Since the ion beam contains a large number of interfering ions and sample matrix ions, collisions between the ions to be measured and these ions occur, such as the A ions and B ions in the aforementioned example. If only collisions with helium molecules occur, the kinetic energy will become 22% of the initial kinetic energy after 15 collisions, but if the A ions and B ions collide, the kinetic energy of the ions will decrease by half after one collision (which can be calculated according to the aforementioned formula). If the ions to be measured collide with ions having a larger mass number than themselves, the kinetic energy lost will be more. If the ions collide with helium molecules for more than 12 times, the final kinetic energy of the ions will be lower than 3 eV, so the interfering ions and the ions to be measured are blocked by the subsequent potential barrier, resulting in a decrease in the determination sensitivity.

[0074] The utility model discloses a kind of unique rotating arrangement multipole rod collision / reaction pool, after ion beam enters collision / reaction pool, because multipole rod ion guide is rotating arrangement, in addition to providing with axial vertical shock constraint to ion beam, it can also provide a kind of rotating torque consistent with the rotating direction of multipole rod to ion beam, so that ion beam always keeps uniform rotating direction under the action of this torque, greatly reduce the mutual collision between ions, improve the through efficiency of ion to be measured under collision mode, so as to improve the sensitivity of instrument under collision mode.

[0075] The embodiment can improve the initial kinetic energy of ions and eliminate zero kinetic energy ions. The parallelly arranged multipole rod ion guide is mainly the kinetic energy generated by the ion source plus the kinetic energy generated by the negative bias of the multipole rod ion guide when the ions enter the collision / reaction pool. Generally, it is in the axial direction. After a series of collisions, the kinetic energy of ions decreases continuously. A small amount of ions lose axial kinetic energy due to excessive collision times. These ions are prone to collision between subsequent ions on one hand, and can only be carried out by collision gas on the other hand, which will directly affect the efficiency of collision and reaction.

[0076] In summary, the utility model embodiment provides a rotating collision / reaction pool of inductively coupled plasma mass spectrometer, which comprises a plurality of rod electrodes 201 arranged in a rotating structure around the longitudinal axis of the shell 10 to form a multipole rod ion guide 20. The rotating structure generates a certain torque on the ion beam entering the guide, allowing the ion beam to oscillate forward while rotating and compressing at a set angle. This allows the ions to move in a spiral pattern in the collision / reaction pool according to the rotating direction of the rod electrodes 201, thereby reducing the mutual collision between ions, suppressing the rapid decay of the kinetic energy of the ions to be measured, and greatly improving the ion transmission efficiency under collision mode. In addition, the multipole rod ion guide arranged in a rotating manner provides a rotating kinetic energy consistent with the rotating direction of the multipole rod ion while providing axial initial kinetic energy to the ions, thereby improving the initial kinetic energy of the ions and significantly reducing the generation of zero kinetic energy ions.

[0077] The above is only the preferred embodiment of the utility model, and it should be pointed out that for ordinary skilled persons in the technical field, without departing from the technical principles of the utility model, a number of improvements and substitutions can be made, which should also be considered as the protection range of the utility model. The above shows and describes the basic principles, main features and advantages of the utility model. For those skilled in the art, it is obvious that the utility model is not limited to the details of the above preferred embodiments, and the embodiments should be considered as exemplary and non-limiting. The scope of the utility model is defined by the appended claims, not the above description, therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the utility model.

[0078] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes only one independent technical solution, and the specification is described in this way only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in the examples can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A rotating collision cell for an inductively coupled plasma mass spectrometer, characterized by, comprising: a housing including a cell inlet, a cell outlet disposed opposite the cell inlet along a longitudinal axis of the housing, and a gas supply port in communication with an interior structure of the housing; and a multipole rod ion guide disposed within the interior of the housing along the longitudinal axis of the housing, the multipole rod ion guide configured to generate an RF confining field effective to confine ions in a radial direction orthogonal to the longitudinal axis of the housing; the multipole rod ion guide including a plurality of elongated rod electrodes arranged to impart a torsional force to ions entering the multipole rod ion guide and to rotate and compress the ions at a set angle while oscillating forward.

2. The reaction cell of claim 1, wherein: the plurality of rod electrodes are located at a predetermined radial distance orthogonal to the longitudinal axis of the housing, the plurality of rod electrodes are circumferentially spaced apart from each other around the longitudinal axis, and define an inlet and an outlet of the multipole rod ion guide.

3. The reaction cell of claim 2, wherein: a field radius of an inlet end of the multipole rod ion guide is greater than a field radius of an outlet end; or a field radius of an inlet end of the multipole rod ion guide is less than a field radius of an outlet end.

4. The reaction cell of claim 1, wherein: an inter-spaced set of the rod electrodes are configured to apply an RF+ potential superimposed on a DC bias potential, and another inter-spaced set of the rod electrodes are configured to apply an RF- potential superimposed on a DC bias potential; wherein RF+ and RF- are radio frequency signals of same frequency and amplitude but opposite phase, the frequency being in a range of 1-20 MHz, thereby generating the RF confining field for the ions.

5. The reaction cell of claim 1, wherein: a negative DC potential barrier is generated at the outlet of the multipole rod ion guide to facilitate smooth ejection of the ions from the collision reaction cell.

6. The reaction cell of claim 1, wherein: the number of the rod electrodes is 2N, where N is an integer and N≥2.

7. The reaction cell of claim 1, wherein: the plurality of rod electrodes are arranged in a rotational configuration around the longitudinal axis of the housing, the rod electrodes have a rotational angle of θ at both ends, where 0°<θ<360°.

8. The reaction cell of claim 1, wherein: the rod electrodes are one of a circular rod, a square rod, a hyperbolic rod, or a concave rod.

9. The reaction cell of claim 1, further comprising: an inlet ion mirror disposed at the cell inlet side of the housing; and an outlet ion mirror disposed at the cell outlet side of the housing. ​ ​

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