Ion analysis device and method

Abstract

The present invention provides an ion analysis device, comprising: a first ion source for providing analyte ions; a second ion source for providing auxiliary ions; the positive and negative polarities of the auxiliary ions are opposite to those of the analyte ions, the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in spatial distribution, and at least part of the analyte ions do not produce a chemical reaction with the auxiliary ions; an ion analyzer for analyzing the analyte ions; an ion transmission device, located between the first ion source and the ion analyzer, for transmitting the analyte ions into the ion analyzer and refusing the auxiliary ions from entering the ion analyzer. The present invention can reduce or eliminate the space charge effect between a large number of analyte ions, thereby improving the ion analysis performance under such conditions, such as sensitivity, resolution, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of ion analysis, and in particular to an ion analysis device and method. Background Art

[0002] The space charge effect refers to the spatial distribution formed by the interaction of charge forces between charged particles. The space charge effect plays an important role in mass spectrometry. Since mass spectrometers are mostly used to analyze ions of a single polarity, when the number of ions is considerable, the space charge effect manifests itself as a wider ion cloud distribution formed by the Coulomb repulsion between ions of the same charge.

[0003] The broadening of the ion cloud caused by the space charge effect often reduces the performance of the mass spectrometer. For example, for the electrospray ionization source currently widely used in mass spectrometers, due to the existence of the space charge effect, the size of the spray beam is greatly expanded, and the sampling efficiency is reduced accordingly, that is, the number of ions that pass through a fixed-size sampling port or vacuum interface (such as a capillary, cone, etc.) and then enter the mass spectrometer is greatly reduced. For occasions with a large and dense number of charges, such as nanoliter spray ion sources, this effect is more significant. Moreover, in the internal space of the vacuum interface, such as the inside of the capillary used for desorption solvent and as a vacuum interface, due to the space charge effect, the ions are easily expanded outward and neutralized by charge on the wall of the capillary, and cannot be maintained in the ionic state for mass spectrometry analysis. After the vacuum interface, the broadening of the ion beam caused by charge repulsion will bring difficulties to ion capture and focusing.

[0004] For pulsed mass spectrometers or ion mobility spectrometers, the broadening of the ion cloud caused by the space charge effect will not only affect the sensitivity, but also reduce the resolution of the analysis. This is because the resolution of such a pulsed analyzer is directly related to the initial broadening of the ion beam. Although in some devices, some compensation measures can be used to reduce the impact of the initial broadening, the spatial broadening still makes the analytical performance unable to break through the physical limit under this condition.

[0005] In patent US6359286, an ion beam of opposite polarity is introduced to reduce the space charge effect in the original ion beam. This method can be applied in the field of high-energy ion implantation. Jon Williams also introduced positive and negative ions into the Paul ion trap at the same time to reduce the space charge effect in the ion trap, and thus observed the improvement of mass spectrum peak shape and resolution (Rapid Communications in Mass Spectrometry, Vol.7, 380-382 (1993)). However, no one has used similar concepts to improve the sensitivity of mass spectrometers, nor has anyone made specific restrictions and explanations on the types and operations of ions of two polarities. Summary of the invention

[0006] The detector settings of a mass spectrometer are usually set and optimized for positive and negative ions separately, which makes it difficult to analyze positive and negative ions at the same time. In addition, the presence of positive and negative ions at the same time is prone to neutralization reactions, making the ions no longer charged and unable to continue mass spectrometry analysis. Therefore, if the sensitivity of a mass spectrometer is to be improved, technicians usually do not think of introducing positive and negative ions into the mass spectrometry process to achieve this.

[0007] In view of the above problems, the purpose of the present invention is to provide an ion analysis device and an ion analysis method, which are mainly used in mass spectrometers, which can reduce or eliminate the space charge effect between a large number of analyte ions, thereby improving the ion analysis performance (such as sensitivity, resolution, etc.) under such conditions.

[0008] To achieve the above-mentioned object and other related objects, the present invention provides an ion analysis device, comprising:

[0009] a first ion source for providing analyte ions;

[0010] A second ion source, used for providing auxiliary ions;

[0011] The positive and negative polarities of the auxiliary ions are opposite to those of the analyte ions, the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in terms of spatial distribution, and at least part of the analyte ions do not chemically react with the auxiliary ions;

[0012] an ion analyzer for analyzing analyte ions;

[0013] The ion transmission device is used to transmit the analyte ions into the ion analyzer and reject the auxiliary ions from entering the ion analyzer; the ion transmission device is located between the first ion source and the ion analyzer.

[0014] According to the above implementation, the space charge effect between analyte ions can be significantly reduced, the ion cloud broadening of the analyte ions can be reduced, and the analysis performance of ion analysis instruments (such as mass spectrometers, ion mobility spectrometers, etc.) can be significantly improved.

[0015] Preferably, the charge center of the auxiliary ion is located inside the auxiliary ion structure.

[0016] According to the above embodiment, by setting the charge center of the auxiliary ion inside the auxiliary ion structure, the auxiliary ion can effectively attract the analyte ions to its surroundings to reduce the space charge effect without neutralizing the analyte ions or reacting with the analyte ions to form other substances.

[0017] Preferably, the number of ions neutralized by the reaction of the analyte ions with the auxiliary ions accounts for no more than 1%, 5%, 10%, 20%, 30%, 40% or 50% of the total analyte ions.

[0018] According to the above-mentioned embodiment, by further limiting the number of ions that are neutralized by the reaction between the analyte ions and the auxiliary ions and the proportion range of the total analyte ions, the range and degree of chemical reaction that is not easy to occur are clearly defined, so that the effect of the auxiliary ions on weakening the space charge effect is more significant, but it does not neutralize the analyte ions and does not introduce other interferences.

[0019] Preferably, it also includes: a vacuum interface, at least one of which is located after the first ion source and before the ion transmission system.

[0020] According to the above embodiment, by providing a vacuum interface, an ion cloud can be introduced, thereby effectively analyzing the ions.

[0021] Preferably, the ion transmission device comprises: an ion optical device, which is driven by a radio frequency voltage, and the electric field generated by the radio frequency voltage can simultaneously bind the analyte ions and the auxiliary ions.

[0022] According to the above embodiment, by setting up an ion optical device, the electric field generated by the radio frequency voltage can simultaneously bind the analyte ions and the auxiliary ions, thereby effectively guiding the ions. In the presence of auxiliary ions of opposite polarity, the broadening of the analyte ions will be suppressed to a certain extent, which is conducive to efficient ion capture, guidance and focusing.

[0023] Preferably, a DC voltage is applied to the ion transmission device, and the electric field formed by the DC voltage can drive the analyte ions into the ion analysis device and reject the auxiliary ions from entering the ion analysis device.

[0024] According to the above embodiment, the analyte ions can smoothly enter the second stage vacuum from the first stage vacuum, but the auxiliary ions with opposite polarity are rejected from entering the second stage vacuum, thereby improving the sensitivity of the analysis.

[0025] Preferably, the vacuum interface is a capillary structure, and two ends of the capillary are respectively close to the atmospheric pressure environment and the vacuum.

[0026] Preferably, the first ion source and the second ion source are electrospray ionization sources, laser ionization sources, chemical ionization sources, electron bombardment ionization sources, inductively coupled plasma ionization sources, or ion optical modules that can provide ions and are located upstream of the ion analyzer.

[0027] Preferably, the first ion source and the second ion source can work alternately in time division, and can make the ion cloud of the analyte ions and the ion cloud of the auxiliary ions generated at different times overlap in spatial distribution at the same time.

[0028] According to the above embodiment, the positive ion cloud of the analyte ion and the negative ion cloud of the auxiliary ion are generated alternately, and sampling and analysis are performed in the overlapping area, which further improves the accuracy of the analysis.

[0029] Preferably, the ion analyser is a mass analyser.

[0030] Preferably, the mass analyzer includes one or more of a quadrupole type, an ion trap type, a time-of-flight type, a magnetic mass spectrometer type or a Fourier transform type.

[0031] Preferably, the mass analyzer is of a time-of-flight type, and the region where the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in spatial distribution is located in the front stage of the repulsion region of the time-of-flight mass spectrometer.

[0032] According to the above embodiment, the presence of the auxiliary ion cloud can reduce the broadening caused by the space charge effect of the analyte ion cloud, thereby further compressing the ion beam, thereby effectively improving the mass spectrum resolution.

[0033] Preferably, the ion analyzer is an ion mobility spectrometer.

[0034] Preferably, it also includes: an ion mobility analyzer, the number of which is one, the ion mobility analyzer is located upstream of the ion analyzer, the overlapping area of ​​the ion cloud of the auxiliary ions and the ion cloud of the analyte ions is located inside the ion mobility analyzer, and the ion analyzer is a mass analyzer.

[0035] The present invention further provides an ion analysis method, characterized in that it comprises the following steps:

[0036] providing a first ion source to provide analyte ions;

[0037] Providing a second ion source to provide auxiliary ions; the positive and negative polarities of the auxiliary ions are opposite to those of the analyte ions, the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in spatial distribution, and at least part of the analyte ions do not chemically react with the auxiliary ions;

[0038] providing an ion analyzer for analyzing analyte ions;

[0039] An ion transmission device is provided for transmitting analyte ions into the ion analyzer and rejecting auxiliary ions from entering the ion analyzer; the ion transmission device is located between the first ion source and the ion analyzer.

[0040] Preferably, the charge center of the auxiliary ion is located inside the auxiliary ion structure.

[0041] Preferably, the number of ions neutralized by the reaction of the analyte ions with the auxiliary ions accounts for no more than 1%, 5%, 10%, 20%, 30%, 40% or 50% of the total analyte ions.

[0042] Preferably, the method further comprises the following steps:

[0043] A vacuum interface is provided, the vacuum interface having one and being located after the first ion source and before the ion transfer system.

[0044] Preferably, the ion transport device comprises:

[0045] Ion optical device, the ion optical device is driven by a radio frequency voltage, and the electric field generated by the radio frequency voltage can simultaneously bind the analyte ions and the auxiliary ions.

[0046] Preferably, the method further comprises the following steps:

[0047] A direct current voltage is applied to the ion transmission device, and the electric field formed by the direct current voltage can drive the analyte ions to enter the ion analysis device and reject the auxiliary ions from entering the ion analysis device.

[0048] As described above, the ion analysis device and method of the present invention can significantly reduce the space charge effect between analyte ions and reduce the ion cloud broadening of analyte ions by providing a large number of auxiliary ions with opposite polarity to the analyte ions and not easily reacting with the analyte ions, thereby significantly improving the analytical performance of ion analysis instruments (such as mass spectrometers, ion mobility spectrometers, etc.). For example, on the one hand, the ion spatial density is improved, thereby improving the ion transmission efficiency, that is, the sensitivity, in the mass spectrometer; on the other hand, the initial ion cloud broadening is reduced, thereby improving the resolution in the ion mobility spectrometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1It is a structural schematic diagram of the ion analysis device involved in Example 1 of the present invention;

[0050] Figure 2 It is a structural schematic diagram of an ion analysis device involved in Example 2 of the present invention;

[0051] Figure 3 It is a structural schematic diagram of another ion analysis device involved in Example 2 of the present invention;

[0052] Figure 4 Schematic diagram of the structure of the ion analysis device involved in Example 3 of the present invention;

[0053] Figure 5 for Figure 4 Corresponding positive and negative AC high voltage schematic diagram;

[0054] Figure 6 It is a structural schematic diagram of an ion analysis device involved in Example 4 of the present invention;

[0055] Figure 7 It is a structural schematic diagram of an ion analysis device involved in Example 5 of the present invention;

[0056] Figure 8 This is a schematic diagram of the structure of the ion analysis device involved in Example 6 of the present invention.

[0057] Description of reference numerals:

[0058] 1-first ion source; 2-second ion source; 3-first ion cloud; 4-second ion cloud; 3'-first formed ion cloud; 4'-second formed ion cloud; 5-capillary; 6-ion transmission device; 7-ion analyzer; 8-first ion guide device; 9-first vacuum interface; 10-second ion guide device; 11-second vacuum interface; 12-first mass analyzer; 13-first detector; 14-flight cavity; 15-front stage area; 16-operating device; 17-repulsion area; 18-ion gate; 19-ion migration tube; 20-second detector; 21-ground electrode; 22-first electrospray needle; 23-first coaxial tube; 24-second coaxial tube; 25-positive and negative AC high voltage; 26-second electrospray needle; 27-first position; 28-second position; 29-ion cluster; 30-ion steering device; 31-second mass analyzer; 32-third detector. DETAILED DESCRIPTION

[0059] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0060] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0061] Example 1

[0062] Figure 1 A schematic diagram of the structure of an ion analysis device provided in this embodiment, such as Figure 1 As shown, the ion analysis device includes: a first ion source 1, used for providing analyte ions; a second ion source 2, used for providing auxiliary ions; the positive and negative polarities of the auxiliary ions are opposite to those of the analyte ions, and the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in spatial distribution; an ion analyzer 7, used for analyzing the analyte ions; an ion transmission device 6, used for transmitting the analyte ions into the ion analyzer 7 and refusing the auxiliary ions to enter the ion analyzer 7; the ion transmission device 6 is located between the first ion source 1 and the ion analyzer 7.

[0063] According to the implementation scheme provided in this embodiment, the first ion source 1 is used to provide analyte ions. Preferably, the first ion source 1 is an electrospray ionization source in an atmospheric pressure environment, and the polarity is positive (i.e., positive high voltage is applied to the electrospray needle). After spraying, a first ion cloud 3 is generated, and the first ion cloud 3 not only contains a large number of positive ions, but also contains a large number of positively charged droplets. The second ion source 2 is used to provide auxiliary ions, and is preferably an electrospray ionization source, and the polarity is negative (i.e., negative high voltage is applied to the electrospray needle). After spraying, a second ion cloud 4 is generated, and the second ion cloud 4 not only contains a large number of negative ions, but also contains a large number of negatively charged droplets. The second ion cloud 4 of the auxiliary ion overlaps with the first ion cloud 3 of the analyte ion in spatial distribution. Preferably, the overlapping area can be selected at the far end of the spray ion cloud, i.e., the area where the charged droplets are desolvated more fully, or can be selected at the near end of the spray ion cloud, i.e., the area where the ion cloud density is larger. This preferred area can be determined according to the flow rate, temperature and other parameters of the first ion source 1 and the second ion source 2.

[0064] Since a large number of negative ions (i.e., auxiliary ions) are provided in the first ion cloud 3 of the positive ion cloud of the analyte ion, the charge repulsion between the positive ions is largely offset, and the space charge effect is weakened. Starting from a simple model, with a distribution of a spherical ion cloud with a radius of R, the total charge of the positive charge is Q+, and the total charge of the negative charge is Q-, then the electric field intensity of the charge repulsion of a certain positive ion located on the spherical surface can be calculated using Gauss's theorem as follows:

[0065]

[0066] It can be seen that the introduction of negative charges reduces the repulsion between positive charges. Ideally, if the total amount of positive and negative charges is equal and evenly distributed, the space charge effect can even be completely eliminated. In practice, the type and concentration of auxiliary ions can be adjusted to controllably reduce the space charge effect of the analyte ions. In the present embodiment, the spatial distribution of the first ion cloud 3 of the analyte ion cloud is limited, and the spatial density of the ions is greatly improved, which is equivalent to the ion cloud being compressed. It should be noted that the spatial density of the second ion cloud 4 of the negative ion cloud will also be higher than when there is no ion source 1. The analyte ions in the compressed first ion cloud 3 pass through the ion transmission device 6 and enter the ion analyzer 7 for analysis.

[0067] The ion transmission device 6 includes a capillary 5 for the interface between atmospheric pressure and vacuum, the capillary 5 has one or a plurality of parallel capillaries, the capillary 5 is located at a first ion guide device 8 of the first vacuum, a second ion guide device 10 of the second vacuum, a first vacuum interface 9 between the first and second vacuums, and a second vacuum interface 11 between the second and third vacuums. Since the space charge effect of the first ion cloud 3 is suppressed and the ion density is increased, the proportion of ions entering the capillary 5 will also increase significantly, thereby improving the sensitivity of the analysis. The first ion guide device 8 can be an ion optical device driven by radio frequency, such as an electrode array that applies a radio frequency quadrupole field. It is well known to those in the industry that the radio frequency quadrupole field can simultaneously bind analyte ions and auxiliary ions of opposite polarities. The ion analyzer 7 is preferably a mass spectrometer, including a first mass analyzer 12 and a first detector 13.

[0068] In the above embodiment, the weakening of the space charge effect of the analyte ions occurs not only in the overlapping area of ​​the first ion cloud 3 and the second ion cloud 4, but also in any area where auxiliary ions exist during the subsequent transmission of the analyte ions. For example, in the capillary 5, if there are no auxiliary ions, the space charge effect of the analyte ions is usually very serious, and the ion wall collision loss caused by this effect may be as high as 90%, but in the case of auxiliary ions, this loss can be significantly reduced. For another example, at the end of the capillary 5, the supersonic airflow caused by vacuum expansion will cause the ion beam to widen sharply, and the existence of the space charge effect further aggravates the widening, which brings difficulties to the use of the ion guide device 8 for ion capture, guidance and focusing. However, in the present embodiment, when there are auxiliary ions of opposite polarity, the widening of the analyte ions will be suppressed to a certain extent, which is more conducive to efficient ion capture, guidance and focusing.

[0069] In the above embodiment, in order to prevent the auxiliary ions from entering the first mass analyzer 12 and interfering with the mass spectrometry analysis, a DC voltage difference may be applied to part of the ion transmission device, for example, a DC potential lower than that of the ion guide device 8 is applied to the first vacuum interface 9, so that the analyte ions can smoothly enter the second vacuum from the first vacuum stage, but the auxiliary ions with opposite polarity will be rejected from entering the second vacuum stage. The DC voltage difference may also be applied to other parts of the ion transmission device, or between the ion transmission device 6 and the ion analyzer 7.

[0070] In the above-mentioned embodiment, the type and concentration of the auxiliary ions can be artificially selected and optimized. For example, in order to make the auxiliary ions have a more significant effect on the weakening of the space charge effect, but not to the extent of neutralizing the analyte ions and not introducing other interferences, the auxiliary ions need to be selected as ions that are not easy to react chemically with the analyte ions. The scope and degree of the so-called "not easy to react chemically" are well known in the industry. The present invention can be further defined as the number of ions that are neutralized by the reaction of the analyte ions with the auxiliary ions, accounting for no more than 1%, 5%, 10%, 20%, 30%, 40% or 50% of the total analyte ions, preferably no more than 10%. The auxiliary ions in the present invention can preferably be ions whose charge center is located inside their ion structure, i.e., so-called "caged ions". In this way, the auxiliary ions can still effectively attract the analyte ions to their surroundings and reduce the space charge effect, but will not neutralize the analyte ions, nor will they react with the analyte ions to form other substances. Under the blocking effect of the DC voltage difference of the later stage, the auxiliary ions will smoothly separate from the analyte ions of opposite polarity and will not affect the mass spectrometry analysis.

[0071] In the above-mentioned embodiment, the first ion source 1 and the second ion source 2 can be electrospray ionization sources, or other forms of ionization sources, such as chemical ionization source (CI), photoionization source (PI), electron bombardment ionization source (EI), laser ionization source (MALDI), inductively coupled plasma ionization source (ICP), etc. In addition to the ionization source (ionization source), it can also be an ion source (ion source) in a broad sense, that is, an ion optical device that can provide ions and is located upstream of the ion analyzer. As long as it is ensured that ions of opposite polarity are produced. The analyte ions can be positive ions and the auxiliary ions can be negative ions, and vice versa. The region where ions are produced can be an atmospheric pressure environment or a vacuum environment. The region where the two ions are mixed, that is, the region where the ion cloud produces overlaps, is not limited by the present invention, as long as it is before entering the ion analyzer.

[0072] In the above embodiments, the first mass analyzer 12 may be a quadrupole type, an ion trap type, a time-of-flight type, a magnetic mass spectrometer type, a Fourier transform type, or a combination of the above types.

[0073] Example 2

[0074] Figure 2 and Figure 3 Two structural schematic diagrams of the ion analysis device provided in this embodiment. The ion analysis device provided in this embodiment is based on the implementation of Example 1. Unless otherwise specified, they are the same as the implementation of Example 1 and will not be repeated here.

[0075] like Figure 2 Described, the ion analysis device provided by the present embodiment, based on the implementation method of embodiment 1, the first ion source 1 and the second ion source 2 are both electrospray ionization sources, and the first ion source 1 and the second ion source 2 are placed parallel to each other. A ground electrode 21 is placed between the two ion sources to achieve stable spraying. The ground electrode 21 can avoid mutual interference between positive and negative electrosprays, and at the same time, the positive and negative ion clouds can be closer to the middle to produce a greater degree of spatial overlap. The capillary 5 is arranged in the overlap area and is placed perpendicular to the paper. In the present embodiment, the ground electrode 21 can also be added with a certain DC potential, so that the direction and expansion of the electrospray ion cloud can be adjusted according to actual needs.

[0076] like Figure 3As shown, the ion analysis device provided in this embodiment is based on the implementation of Example 1, and the first ion source 1 and the second ion source 2 are coaxially placed electrospray ionization sources. The first ion source 1 is composed of a first electrospray needle 22 applying positive high voltage and a grounded first coaxial tube 23. Atomizing gas or heating gas can be introduced into the coaxial tube to help form a spray or help desolvation, and the ion source forms an analyte ion cloud first ion cloud 3; the second ion source 2 is composed of a grounded first coaxial tube 23 and an outer second coaxial tube 24 applying negative high voltage, and the ion source forms an auxiliary ion cloud second ion cloud 4 surrounding the outer side of the first ion cloud 3; the two beams of ion clouds form a coaxial overlap area, which can achieve the purpose of reducing the space charge effect in the analyte ion cloud first ion cloud 3. It should be noted that in this example, the second ion source 2 may not adopt the above-mentioned electrospray form, but a large number of negative ions generated by any ionization method are introduced between the first coaxial tube 23 and the outer second coaxial tube 24, and the auxiliary ion cloud second ion cloud 4 can also be formed.

[0077] Example 3

[0078] Figure 4 The ion analysis device provided in this embodiment is a schematic diagram of the structure of the ion analysis device provided in this embodiment. The ion analysis device provided in this embodiment is based on the implementation of embodiment 1. Unless otherwise specified, it is the same as the implementation of embodiment 1 and will not be described in detail here.

[0079] like Figure 4 As shown, in this embodiment, the positions where the first ion source 1 and the second ion source 2 generate ions can be at the same position. It should be noted that the first ion source 1 and the second ion source 2 work alternately in time division. Taking the electrospray ionization source as an example, the analyte liquid flow of the first ion source 1 enters from the first position 27, and the liquid flow for generating auxiliary ions of the second ion source 2 enters from the second position 28. The two ion sources use the same second electrospray needle 26 to generate electrospray. However, by applying the following to the electrospray needle: Figure 5The positive and negative AC high voltage 25 shown in the figure, which changes with time, can cause the first ion cloud 3 of the positive ion cloud of the analyte ion and the second ion cloud 4 of the negative ion cloud of the auxiliary ion to be generated alternately. The two ion clouds do not overlap in spatial position when they are just generated, but a certain mechanism can be applied to make the two ion clouds overlap in the process of downward movement and transmission, and the capillary 5 is used to sample in the overlapping area; preferably, a DC electric field is applied in the space to accelerate the positive ion cloud and decelerate the negative ion cloud, so that the positive ion cloud generated later can catch up with the negative ion cloud; preferably, negative ions with lower mobility are selected as auxiliary ions, so that the positive ions can catch up with the negative ions faster; preferably, radio frequency voltage, air standing wave or other forms are used to trap the ion clouds of two polarities to make them mix. It should be noted that in this example, for some analytes that can generate positive and negative charged ions under different conditions, the liquid flows at the first position 27 and the second position 28 can be merged into the same path, that is, the type of auxiliary ions is the same as that of the analyte ions, but the positive and negative polarities are different.

[0080] Example 4

[0081] Figure 6 This is a schematic diagram of the structure of the ion analysis device provided in this embodiment. The ion analysis device provided in this embodiment is based on the implementation of Example 1. Unless otherwise specified, it is the same as the implementation of Example 1 and will not be repeated here.

[0082] like Figure 6 As shown, this embodiment uses an orthogonal time-of-flight mass spectrometer as a mass analyzer. Specifically, in this embodiment, the first ion source 1 and the second ion source 2 of the electrospray ionization source with positive and negative polarity can still be used to generate the first ion cloud 3 and the second ion cloud 4; after the first ion cloud 3 and the second ion cloud 4 are transmitted, they each form the first formed ion cloud 3' and the second formed ion cloud 4', enter the front-stage area 15 before the flight cavity 14 (i.e., the front-stage area of ​​the repulsion zone 17), and mix in this area. The front-stage area 15 usually requires an operating device 16, and the operating device 16 can cool, compress, collimate, etc. the first formed ion cloud 3' of the analyte ion cloud to improve the resolution of the time-of-flight mass spectrometer. It should be noted that the presence of the auxiliary ion cloud second formed ion cloud 4' can reduce the broadening caused by the space charge effect of the first formed ion cloud 3' of the analyte ion cloud, thereby further compressing the ion beam to bring higher mass spectrum resolution. The mixing of positive and negative ion clouds can also occur in the repulsion zone 17 of the time-of-flight mass spectrometer to perform time-of-flight mass spectrometry analysis immediately after compression.

[0083] Example 5

[0084] Figure 7This is a schematic diagram of the structure of the ion analysis device provided in this embodiment. The ion analysis device provided in this embodiment is based on the implementation of Example 1. Unless otherwise specified, it is the same as the implementation of Example 1 and will not be repeated here.

[0085] like Figure 7 As shown, in this embodiment, the ion analyzer 7 is not a mass spectrometer, but an ion mobility spectrometer, which includes an ion gate 18, an ion migration tube 19 for mobility analysis, and a second detector 20. The ion transmission device 6 can not only be used for the transmission of the analyte ions produced by the first ion source 1, but also can help the charged droplets to desorb solvent and produce ions. The second ion cloud 4 of the auxiliary ions produced by the second ion source 2 can be mixed with the first ion cloud 3 of the analyte ion cloud before the ion gate 18 to reduce the spatial distribution of the analyte ion cloud and produce a thinner ion beam to improve the pass rate and sensitivity of the analyzer. This mixing can also occur after the ion gate 18 and before the mobility analysis to reduce the broadening of the initial ion beam to improve the resolution of the migration spectrum. If the ion gate is a multilayer electrode structure, this mixing can occur in the ion gate, which can also improve the resolution of the migration spectrum.

[0086] Example 6

[0087] Figure 8 This is a schematic diagram of the structure of the ion analysis device provided in this embodiment. The ion analysis device provided in this embodiment is based on the implementation of Example 1. Unless otherwise specified, it is the same as the implementation of Example 1 and will not be repeated here.

[0088] like Figure 8As shown, the ion analysis device provided in this embodiment is a mobility spectrum-mass spectrometry analysis device. The ions generated by the first ion source 1 of the analyte ion source pass through the ion transmission device 6 and the ion gate 18, and enter the ion migration tube 19 for mobility analysis. In the migration tube, ions with different mobilities are separated to form different ion clouds or ion clusters 29. The ions separated by the migration spectrum pass through an ion steering device 30 and enter the ion analyzer 7 for mass spectrometry analysis. The ion analyzer 7 here may include a second mass analyzer 31 and a third detector 32. The migration spectrum resolution of the ion migration tube 19 is negatively correlated with the spatial charge effect of the ion cluster 29. For example, when the concentration of a certain analyte ion is large, the spatial charge effect is strong, and the migration spectrum peak will be significantly widened and the resolution will decrease. At this time, the auxiliary ions of opposite polarity are introduced by the second ion source 2, and the ion cloud 4 of the auxiliary ions overlaps with the ion cluster 29 in space, which can reduce the spatial broadening of the ion cluster 29 and improve the migration spectrum resolution. The ion transfer tube 19 in this embodiment can also be replaced by other types of mobility spectrometry analysis devices, such as a traveling wave mobility analyzer, a trapped ion mobility analyzer (TIMS), a differential ion mobility spectrometer (DMA), a high-field asymmetric waveform ion mobility spectrometer (FAIMS), etc. In particular, for a TIMS type mobility analyzer, the device and method of the present invention can not only improve the resolution of the mobility analysis, but also avoid the capacity saturation of ion trapping, thereby improving the dynamic range.

[0089] The present invention further provides an ion analysis method, comprising the following steps: providing a first ion source to provide analyte ions; providing a second ion source to provide auxiliary ions; the positive and negative polarities of the auxiliary ions are opposite to those of the analyte ions, and the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in spatial distribution; providing an ion analyzer for analyzing the analyte ions; providing an ion transmission device for transmitting the analyte ions into the ion analyzer and refusing the auxiliary ions to enter the ion analyzer; the ion transmission device is located between the first ion source and the ion analyzer.

[0090] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An ion analysis device, characterized in that: include: a first ion source for providing analyte ions; A second ion source, used for providing auxiliary ions; The positive and negative polarities of the auxiliary ions are opposite to those of the analyte ions; the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in terms of spatial distribution, and at least part of the analyte ions do not chemically react with the auxiliary ions; an ion analyzer, for analyzing the analyte ions; an ion transmission device, used for transmitting the analyte ions into the ion analyzer and rejecting the auxiliary ions from entering the ion analyzer, the ion transmission device being located between the first ion source and the ion analyzer; A DC electric field or electrodes with an applied DC potential control the direction and expansion of the ion cloud of the auxiliary ions and the ion cloud of the analyte ions.

2. The ion analysis device according to claim 1, characterized in that: The charge center of the auxiliary ion is located inside the auxiliary ion structure.

3. The ion analysis device according to claim 1, characterized in that: The proportion of the number of ions neutralized by the reaction of the analyte ions with the auxiliary ions to the total amount of the analyte ions does not exceed any one of 1%, 5%, 10%, 20%, 30%, 40% or 50%.

4. The ion analysis device according to claim 1, characterized in that Also includes: A vacuum interface, at least one of which is provided, and the vacuum interface is located after the first ion source and before the ion transmission device.

5. The ion analysis device according to claim 1, characterized in that The ion transmission device comprises: An ion optical device is driven by a radio frequency voltage, and the electric field generated by the radio frequency voltage can simultaneously bind the analyte ions and the auxiliary ions.

6. The ion analysis device according to claim 1, characterized in that: A direct current voltage is applied to the ion transmission device, and the electric field formed by the direct current voltage can drive the analyte ions to enter the ion analyzer and reject the auxiliary ions from entering the ion analyzer.

7. The ion analysis device according to claim 4, characterized in that: The vacuum interface is a capillary tube, and two ends of the capillary tube are respectively in an environment close to atmospheric pressure and a vacuum environment.

8. The ion analysis device according to claim 1, characterized in that: The first ion source or the second ion source is one of an electrospray ionization source, a laser ionization source, a chemical ionization source, an electron bombardment ionization source, an inductively coupled plasma ionization source, or an ion optical device that can provide ions and is located upstream of the ion analyzer.

9. The ion analysis device according to claim 1, characterized in that: The first ion source and the second ion source work alternately in time division, and can make the ion cloud of the analyte ions and the ion cloud of the auxiliary ions generated at different times overlap in spatial distribution at the same time.

10. The ion analysis device according to claim 1, characterized in that: The ion analyzer is a mass analyzer.

11. The ion analysis device according to claim 10, characterized in that: The mass analyzer is one or more of a quadrupole type, an ion trap type, a time-of-flight type, a magnetic mass spectrometer type or a Fourier transform type.

12. The ion analysis device according to claim 11, characterized in that: The mass analyzer is of a time-of-flight type, and the region where the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in spatial distribution is located in the front stage of the repulsion region of the time-of-flight type mass analyzer.

13. The ion analysis device according to claim 1, characterized in that: The ion analyzer is an ion mobility spectrometer.

14. The ion analysis device according to claim 1, characterized in that Also includes: An ion mobility analyzer is located upstream of the ion analyzer, an overlapping area between the ion cloud of the auxiliary ions and the ion cloud of the analyte ions is located inside the ion mobility analyzer, and the ion analyzer is a mass analyzer.

15. An ion analysis method, characterized in that: include providing a first ion source to provide analyte ions; Providing a second ion source to provide auxiliary ions, wherein the positive and negative polarities of the auxiliary ions are opposite to those of the analyte ions, the ion cloud of the auxiliary ions overlaps with the ion cloud of the analyte ions in spatial distribution, and at least part of the analyte ions do not chemically react with the auxiliary ions; providing an ion analyzer for analyzing the analyte ions; providing an ion transmission device, located between the first ion source and the ion analyzer, for transmitting the analyte ions into the ion analyzer and rejecting the auxiliary ions from entering the ion analyzer; Electrodes that provide a DC electric field or an additional DC potential control the direction and expansion of the ion cloud of the auxiliary ions and the ion cloud of the analyte ions.

16. The ion analysis method according to claim 15, characterized in that: The charge center of the auxiliary ion is located inside the auxiliary ion structure.

17. The ion analysis method according to claim 15, characterized in that: The number of ions neutralized by the reaction of the analyte ions with the auxiliary ions accounts for no more than 1%, 5%, 10%, 20%, 30%, 40% or 50% of the total number of analyte ions.

18. The ion analysis method according to claim 15, characterized in that: The following steps are also included: A vacuum interface is provided after the first ion source and before the ion transport system.

19. The ion analysis method according to claim 15, characterized in that: The ion transmission device includes an ion optical device driven by a radio frequency voltage, and the electric field generated by the radio frequency voltage can simultaneously confine the analyte ions and the auxiliary ions.

20. The ion analysis method according to claim 15, characterized in that: The following steps are also included: A direct current voltage is applied to the ion transmission device, and the electric field formed by the direct current voltage can drive the analyte ions into the ion analyzer and reject the auxiliary ions from entering the ion analyzer.

Images