Mass spectrometer for analyzing analyte sample

Abstract

The present invention relates to a mass spectrometer for analyzing an analyte sample, comprising: a plasma ion source configured to generate a plasma; an interface device configured to form a plasma flux from the plasma and flow it to the mass analyzer, where the interface device comprises at least one cone comprising an orifice through which the plasma flux flows and at least one capillary comprising an inlet and an outlet, an outlet and arranged and configured to introduce an analyte sample into the plasma flux at the orifice or in the plasma expansion zone downstream of the orifice such that the analyte sample is ionized by means of the plasma flux and ions are generated, with the outlet in contact with the plasma flux; a mass analyzer configured to filter and / or separate the generated ions; and a detector configured to detect ions generated from the analyte sample.

Description

Technical Field

[0001] The present invention relates to a mass spectrometer for analyzing an analyte sample. Background Art

[0002] In a mass spectrometer, the molecules or atoms of the sample are first transferred into the gas phase and ionized. For the ionization, various methods known from the prior art are available, such as inductively coupled plasma ionization (ICP) or microwave plasma or optical (laser-induced) plasma, which ionize the sample with the aid of a plasma. To date, several different types of inductively coupled plasma mass spectrometers (ICP-MS) are available, such as quadrupole ICP-MS or time-of-flight ICP-MS.

[0003] After ionization, the ions reach the mass analyzer through a vacuum interface, where they are filtered and / or separated according to their mass-to-charge ratio m / z. Different types of interfaces and operating modes are based, for example, on the application of static or dynamic electric and / or magnetic fields or on different flight times of different ions. Different types of mass analyzers include single, multiple or hybrid arrangements of analyzers, such as quadrupoles, triple quadrupoles, time of flight (TOF), ion traps, orbital traps or magnetic sectors. Finally, the separated ions are directed to a detector, which is, for example, one of a photoion multiplier, an ion-electron multiplier, a Faraday collector, a Daly detector, a microchannel plate or a channel multiplier.

[0004] Inductively coupled plasma mass spectrometers (ICP-MS) are used, for example, for trace element analysis. Typically, ICP-MS analysis involves complete nebulization and subsequent ionization of the test sample by means of a plasma ion source before the resulting elemental ions are quantified by a spectrometer.

[0005] ICP-MS systems are less suitable or even unsuitable for the analysis of molecules or organic substances, which are usually studied by mass spectrometers using different types of ionization sources, such as spray ionization (ESI) or atmospheric pressure chemical ionization (APCI). Such methods are optimized for the ionization of molecules and do not result in atomization of the molecules. Other mass spectrometry systems suitable for molecular analysis are, for example, selected ion flow tube mass spectrometers (SIFT-MS) or proton transfer reaction mass spectrometers (PTR-MS).

[0006] A mass spectrometer capable of studying aerosolized matter as well as molecular and / or organic matter is needed. Summary of the invention

[0007] It is therefore an object of the present invention to provide a mass spectrometer capable of analysing both nebulised and ionised molecules.

[0008] This object is achieved by a mass spectrometer for analyzing an analyte sample, the mass spectrometer comprising:

[0009] • a plasma ion source configured to generate a plasma;

[0010] • an interface device configured to form a plasma flux from the plasma and flow it to the mass analyzer, wherein the interface device includes at least one cone and at least one capillary, wherein the at least one cone includes an orifice through which the plasma flux flows, wherein the at least one capillary includes an inlet and an outlet, and is arranged and configured to introduce an analyte sample into the plasma flux at the orifice or in a plasma expansion region downstream of the orifice so that the analyte sample is ionized and ions are generated by means of the plasma flux, wherein the outlet is in contact with the plasma flux;

[0011] • a mass analyzer configured to filter and / or separate the generated ions; and

[0012] • A detector configured to detect ions generated from the analyte sample.

[0013] The analyte sample can be a gas, liquid or solid. The plasma flux includes positively charged and excited neutral atoms and metastable atoms of the gas that generates the plasma. At least one cone generally includes a circular base, but may also include bases of different shapes, such as square, polygonal or rectangular bases. By introducing the analyte sample into the plasma flux in the region of the orifice, the analyte sample will be ionized rather than atomized by the plasma flux, because the density and temperature of the plasma flux will be reduced compared to the region of the plasma ion source. The analyte sample can be supplied, for example, at the position of the orifice or in the plasma expansion zone behind the orifice. Advantageously, the outlet is arranged in the orifice of at least one cone. When the outlet of at least one capillary contacts the plasma flux, the outlet will be continuously cleaned by the plasma flux, such as etching. This allows the introduction of a liquid analyte sample into the plasma flux. Typically, the introduction of a liquid analyte sample will result in residues and accumulation at the outlet. This problem is overcome by the present invention.

[0014] By adding at least one capillary to the mass spectrometer, both nebulized and ionized molecules can be analyzed. For the analysis of nebulized molecules, the analyte sample is introduced directly into the plasma ion source, while for the analysis of ionized molecules, the analyte sample is introduced by means of at least one capillary.

[0015] In one embodiment of the invention, the capillary is arranged in a plane parallel to the plane in which at least the first cone is arranged. The capillary may be arranged at an angle to the plasma flux, in particular at an angle between 40° and 130°, in particular at right angles to the plasma flux. This arrangement of the capillary enhances the cleaning of the outlet by the plasma flux.

[0016] In another embodiment, the interface device includes a plurality of capillaries. Each capillary can be used for the same analyte sample or for different analyte samples. Some capillaries can also be used for the same analyte sample, while other capillaries are used for another analyte sample. For application purposes, a plurality of capillaries means two or more capillaries.

[0017] Advantageously, several capillaries are arranged radially adjacent to each other. For example, several capillaries can be arranged in a disc-like manner and / or several capillaries can be arranged so that their respective outlets surround the orifice, wherein the capillaries extend outwardly from the orifice. Such an arrangement of several capillaries saves space.

[0018] Another embodiment comprises that the outlet is arranged at a predetermined distance from the plasma ion source and / or the at least one cone, so that the analyte sample is ionized with a plasma flux of a predetermined density. The density of the plasma decreases with increasing distance from the plasma ion source by means of the at least one cone. By adjusting the distance between the outlet and the at least one cone and / or the plasma ion source, the analyte sample can be ionized with a plasma flux of a predetermined density. Advantageously, the position of the outlet is adjustable, for example, the position of the at least one capillary and / or the at least one cone (in the case where the at least one capillary is arranged in the at least one cone) can be adjusted.

[0019] In one embodiment, at least one capillary is at least partially arranged within or adjacent to at least one cone.

[0020] At least the first cone can be a sampler cone, a frustum cone or a super frustum cone. Typically, the frustum cone is arranged downstream of the sampler cone. The super frustum cone is usually arranged downstream of the frustum cone. For the purposes of the present invention, downstream is intended to refer to a position relative to the path of the plasma flux and / or ion beam.

[0021] At least the first cone may be arranged in a vacuum; in particular if the plasma ion source generates an atmospheric pressure plasma.

[0022] In another embodiment, at least one cone is arranged adjacent to the plasma ion source.At least one cone may also be arranged adjacent to another cone.

[0023] Advantageously, the mass spectrometer comprises a voltage source, which is configured to apply a positive voltage or a negative voltage to at least one cone relative to the potential of the plasma flux. At least one cone is subjected to a positive voltage or a negative voltage relative to the potential of the plasma flux by means of the voltage source. In a typical arrangement, at least one cone is grounded, and the ions generated by the plasma are propelled forward by the plasma and accelerated by the extraction lens toward the mass analyzer. By applying a positive voltage to at least one cone, the positively charged ions generated by the interaction of the analyte sample with the plasma flow are accelerated toward the mass analyzer, thereby increasing the signal intensity of those ions on the detector. Vice versa, applying a negative voltage to at least one cone causes the acceleration of the negatively charged ions generated by the interaction of the analyte sample with the plasma flux, thereby increasing their corresponding signal intensity on the detector. The positive or negative voltage can be applied as a DC voltage or as a voltage pulse.

[0024] The voltage at the at least one cone can be adjusted relative to the potential of the plasma flux between 0 and ±200 V. The positive voltage can advantageously be chosen in the range of 0 to +20 V.

[0025] Another embodiment includes an analyte sample that contains organic, particulate and / or biological matter. The analyte sample may include liquids and cells, viruses, bacteria, and the like.

[0026] In another embodiment, the at least one capillary can be connected to a gas chromatograph or a liquid chromatograph or a biological sample introduction system. The analyte sample prepared by the gas chromatograph or the liquid chromatograph or the biological sample introduction system can be directly injected into the mass spectrometer of the present invention by means of at least one capillary. The biological sample introduction system is preferably a microbial sample introduction system. The microbial sample introduction system is particularly configured to process microbial samples, such as cells, bacteria and viruses.

[0027] In another embodiment, the mass spectrometer includes two or more detectors. In particular, different detectors can be selected. For example, the mass spectrometer can include a first detector configured to detect atomized ions and / or molecules and a second detector configured to detect ionized molecules.

[0028] In another embodiment, the mass spectrometer comprises two or more mass analysers.The mass analysers may be quadrupole mass analysers, time-of-flight analysers, triple quadrupole mass analysers, ion traps, orbital traps or magnetic sector analysers.

[0029] The plasma ion source may be configured to generate plasma at atmospheric pressure. For example, the plasma ion source may be an inductively coupled plasma torch. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In the following, based on the Figures 1 to 4The present invention and its preferred embodiments are described.

[0031] Figure 1 : The first embodiment of the mass spectrometer of the present invention.

[0032] Figure 2 : The second embodiment of the mass spectrometer of the present invention.

[0033] Figure 3 : A first embodiment of a cone with a capillary.

[0034] Figure 4 : Second embodiment of the cone with capillaries. DETAILED DESCRIPTION

[0035] Figure 1 An exemplary mass spectrometer 10 of the present invention is shown in FIG. The mass spectrometer 10 includes a plasma ion source 20 for generating a plasma 28, an interface device 32 for forming a plasma flux 61 from the plasma 28 and flowing it to a mass analyzer 50, and a detector 52. The plasma ion source 20 may be an ICP torch having a radio frequency coil 30. The ICP torch is connected to a plasma forming gas 24 and an auxiliary gas 26 to maintain the plasma 28.

[0036] The interface device 32 includes at least one cone 60 having an orifice 62 through which a plasma flux 61 flows, and at least one capillary 70 having an inlet 71 and an outlet 72. The at least one cone 60 may be a sampler cone 34, a frustum cone 40, or a super frustum cone 48. The at least one capillary 70 is arranged and configured to introduce the analyte sample 12 into the plasma flux 61 in its plasma expansion region 64 or at the orifice 62, so that the analyte sample 12 is ionized by means of the plasma flux 61 and ions are generated.

[0037] exist Figure 1 In the embodiment of the present invention, at least one capillary 70 is arranged adjacent to the sampler cone 34. However, the at least one capillary 70 can also be arranged adjacent to or in the sampler cone 34, the truncating cone 40 and / or the super truncating cone 48. Preferably, the analyte sample 12 is supplied to the orifice 62 of the at least one cone 60. The interface device 32 may include several capillaries 70. Preferably, the at least one capillary 70 is arranged in a plane parallel to the plane in which the at least one cone 60 is arranged. The mass spectrometer 10 also includes a mass analyzer 50 and a detector 52. The recording device 54 can be connected to the detector 52.

[0038] The plasma ion source 20 may be configured to generate an atmospheric pressure plasma. At least one cone 60 may be arranged in a vacuum. Figure 1In the example of the embodiment of the present invention, cone 34, cone 40 and cone 48 each have an orifice 36, an orifice 42, an orifice 49, and a plasma flux 61 is transferred from the plasma ion source 20 to the first vacuum region 38, the second vacuum region 43 and the third vacuum region 44 through the orifice 36, the orifice 42, and the orifice 49. The third vacuum region 44 includes an extraction electrode 46, which is configured to extract the ion beam from the plasma flux 28 into a fourth vacuum region 55 and toward the mass analyzer 50. Generally, the pressure in the vacuum region decreases from the first vacuum region 38 to the fourth vacuum region 55. The density and temperature of the plasma flux 61 generally decrease from the orifice 36 of the sampler cone 34 to the extraction lens 46. The outlet 72 of the at least one capillary 70 can be arranged at a predetermined distance from the plasma ion source 20 and / or the at least one cone 60, so that the analyte sample 12 is ionized with the plasma flux 28 of a predetermined density.

[0039] Since the mass spectrometer 10 can analyze both ionized atoms and ionized molecules, it may be advantageous if the mass spectrometer 10 includes two or more detectors 52 and / or two or more mass analyzers 50. Such an embodiment is Figure 2 Shown in.

[0040] Figure 2 Also shown is an embodiment of the mass spectrometer 10 in which three cones are modified to include at least one capillary 70. The three cones are the sampler cone 34, the skimmer cone 40, and the super skimmer cone 48. Obviously, other arrangements of at least the capillary 70 are also possible. Two or more mass analyzers 50 can be selected so that each mass analyzer 50 is configured to filter ions generated from a particular capillary 70. For example, the mass analyzer 50 on the left can be adapted to filter ions generated by introducing the analyte sample 12 at the sampler cone 34. The mass analyzer 50 in the middle can be adapted to filter ions generated by introducing the analyte sample 12 at the skimmer cone 40, and so on.

[0041] Figure 3 A first embodiment of at least one cone 60 is shown. At least one cone 60 has been modified so that a number of capillaries 70 pass through it. A corresponding outlet 72 is arranged so that the analyte sample 12 can be supplied to the plasma flux 61 at different positions in the plasma expansion zone 64. The outlet 72 contacts the plasma flux 61 so that the outlet 72 is cleaned by the plasma flux 61. Cleaning the outlet 72 by means of the plasma flux 61 is particularly advantageous for liquid analyte samples. For example, the liquid analyte sample can include organic, particulate and / or biological substances. The inlet 71 can include a connection device configured to connect the capillary 70 to a gas chromatograph or a liquid chromatograph or a biological sample introduction system.

[0042] In order to introduce the capillary 70 into the at least one cone 60, the at least one cone 60 may include at least one capillary channel 75 through which the at least one capillary 70 is guided. Preferably, the at least one cone 60 may include several capillary channels 75. The at least one cone 60 may be arranged in front of, i.e. upstream of, the extraction electrode 46. The extraction electrode 46 may be configured to generate an ion beam from the plasma flux 61. As previously mentioned, other positions of the at least one cone 60 are also possible.

[0043] Furthermore, a positive or negative voltage may be applied to the at least one cone 60 in order to accelerate the positively or negatively charged ionized molecules toward the mass analyzer 50. A voltage source 76 may be used to apply a voltage to the at least one cone 60.

[0044] exist Figure 4 60. In the embodiment, a capillary 70 is arranged in at least one cone 60, and each outlet 72 is arranged at the orifice 62. Preferably, the capillaries 70 are arranged radially adjacent to each other. In order to guide the capillary 70, at least one cone 60 may include at least one capillary channel 75. If several capillary channels 75 are present in at least one cone 60, it may be advantageous to arrange the capillary channels 75 radially adjacent to each other. The capillary 70 can be connected to a gas chromatograph, a liquid chromatograph or a biological sample introduction system. A heating element 73 can be arranged next to the capillary 70 for heating the analyte sample 12.

[0045] Reference numerals

[0046] 10Mass Spectrometer

[0047] 12 Analyte samples

[0048] 20 Plasma ion source

[0049] 24 Plasma forming gas

[0050] 26 auxiliary gas

[0051] 28 Plasma

[0052] 30 RF Coil

[0053] 32 interface devices

[0054] 34 Sampler Cone

[0055] 36 Orifice of the sampler cone

[0056] 38 First Vacuum Area

[0057] 40 interceptor cone

[0058] 42 Orifice of the intercepting cone

[0059] 43 Second Vacuum Area

[0060] 44 The third vacuum area

[0061] 46 Extraction Electrode

[0062] 47 Ion Optical System

[0063] 48 Super-skimming cone

[0064] 49 Orifice of the super-skimming cone

[0065] 50 Mass Analyzer

[0066] 52 detectors

[0067] 54 Recording Device

[0068] 55 Fourth Vacuum Area

[0069] 60 cones

[0070] 62 cone orifice

[0071] 61 Plasma Flux

[0072] 64 Plasma expansion zone

[0073] 66 Ion Beam

[0074] 70 capillary

[0075] 71 Entrance

[0076] Exit 72

[0077] 73 Heating element

[0078] 75 capillary channel

[0079] 76 Voltage Source

Claims

1. A mass spectrometer (10) for analyzing an analyte sample (12), comprising: • a plasma ion source (20) configured to generate a plasma (28); • an interface device (32) configured to form a plasma flux (61) from the plasma (28) and to flow it toward a mass analyzer (50), wherein the interface device (32) comprises at least one cone (60) and at least one capillary (70), wherein the at least one cone (60) comprises an orifice (62) through which the plasma flux (61) flows, wherein the at least one capillary (70) comprises an inlet (71) and an outlet (72), and is arranged and configured to introduce the analyte sample (12) into the plasma flux (61) at the orifice (62) or in a plasma expansion region (64) downstream of the orifice (62), so that the analyte (12) sample is ionized by means of the plasma flux (61) and ions are generated, wherein the outlet (72) is in contact with the plasma flux (61); • the mass analyser (50), the mass analyser being configured to filter and / or separate the generated ions; as well as • A detector (52) configured to detect ions generated from the analyte sample (12).

2. The mass spectrometer (10) according to claim 1, in, The at least one capillary (70) is arranged in a plane parallel to a plane in which the at least first cone (60) is arranged.

3. The mass spectrometer (10) according to any one of claims 1 to 2, in, The interface device (32) comprises a plurality of capillaries (70).

4. The mass spectrometer (10) according to claim 3, in, The plurality of capillaries (70) are arranged radially adjacent to each other.

5. The mass spectrometer (10) according to any one of claims 1 to 4, in, The outlet (72) is arranged at a predetermined distance from the plasma ion source (20) and / or the at least one cone (60) so that the analyte sample (12) is ionized at a predetermined density of the plasma flux (61).

6. The mass spectrometer (10) according to any one of claims 1 to 5, in, The at least one capillary (70) is arranged within or adjacent to the at least one cone (60).

7. The mass spectrometer (10) according to any one of claims 1 to 6, in, The at least first cone (60) is a skimmer cone, a sampler cone or a super skimmer cone.

8. The mass spectrometer (10) according to any one of claims 1 to 7, in, The at least first cone (60) is arranged in a vacuum.

9. The mass spectrometer (10) according to any one of claims 1 to 8, in, The at least one cone (60) is arranged adjacent to the plasma ion source (20).

10. The mass spectrometer (10) according to claim 9, in, The mass spectrometer includes a voltage source (76) configured to apply a positive voltage or a negative voltage to the at least one cone (60).

11. The mass spectrometer (10) according to claim 9, in, The voltage source (76) is configured to adjust the positive or negative voltage at the at least one cone (60) between 0 and ±200 V relative to the potential of the plasma flux (61).

12. The mass spectrometer (10) according to any one of claims 1 to 11, in, The analyte sample (12) contains organic, particulate and / or biological matter.

13. The mass spectrometer (10) according to any one of claims 1 to 12, in, The at least one capillary (9) can be connected to a gas chromatograph or a liquid chromatograph or a biological sample introduction system.

14. The mass spectrometer (10) according to any one of claims 1 to 13, in, The mass spectrometer (10) includes two or more detectors (52).

15. The mass spectrometer (10) according to any one of claims 1 to 14, in, The plasma ion source (20) is configured to generate a plasma (28) at atmospheric pressure.

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