Ion source, projectile for the ion source, ion source assembly, and ion detecting device

Abstract

The invention refers to an ion source for an ion detecting device, wherein the ion source is configured to generate ions of an analyte substance, wherein the ion source comprises: a collision structure; an accelerating device configured to accelerate the analyte substance towards the collision structure for collision therewith to scatter the analyte substance and thereby induce ionisation of the analyte substance by triboelectric charge transfer; and collection means for guiding the ionised analyte substance to the ion detecting device.

Description

[0001] ION SOURCE, PROJECTILE FOR THE ION SOURCE, ION SOURCE ASSEMBLY, AND ION DETECTING DEVICE

[0002] Field of the Invention

[0003] The present invention relates to an ion source for an ion detecting device, The ion source is configured to generate ions of an analyte substance.

[0004] The present invention further relates to a projectile for the ion source and to an ion source assembly including the ion source and the projectile.

[0005] The present invention also refers to ion detecting device including the ion source assembly as well as a method for generating ions of an analyte substance for an ion detecting device.

[0006] Background

[0007] Mass spectrometers are commonly known instruments that are used to measure the mass-to-charge ratio of ions. The results are presented as a mass spectrum which is a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometers are used in many different fields and are applied to pure samples as well as complex mixtures.

[0008] An example of a mass spectrometer includes electrospray ionisation source which generates the ions of an analyte substance to be measured by the mass spectrometer in atmospheric pressure conditions. The ions generated by the electrospray ionisation source are sucked into a vacuum, for example by a heated capillary, where remaining droplets from electrospray ionisation source are desolved. Thereafter, the ions are guided into a vacuum region of the mass spectrometer, where they are collected and focused for further transfer and analysis.

[0009] This exemplary mass spectrometer only works for ions. For some mass spectrometers, droplets generated by electrospray ionisation source that are not changed into ions, passing through the entire system without interaction with its elements. The ion detector of the electrospray ionisation source can be of type that detect only ions. Other known mass spectrometers include a baffle that stops neutrals or bend quadrupole electrodes to reject neutrals. Bend quadrupole electrodes can transfer further only ions. With these systems, ions are filtered.

[0010] US 2019 / 0096649 A1 refers to an ionizing system that includes a channel and a heater coupled to the channel. US 11 ,430,648 B2 discloses an ionization method for use with mass spectrometry or ion mobility spectrometry which is a small molecule compound(s) as a matrix into which is incorporated analyte.

[0011] The present invention has been devised in light of the above considerations. 8628380

[0012] 2

[0013] Summary of the Invention

[0014] At the most general, the invention refers to ionising an analyte substance by accelerating the analyte substance and impacting the analyte substance onto a collision structure. The impact of the analyte substance onto the collision structure generates a triboelectric charge transfer which ionises the analyte substance.

[0015] In a first aspect, an ion source for an ion detecting device is provided. The ion source is configured to generate ions of an analyte substance, optionally a liquid or solid analyte substance. The ion source comprises a collision structure, an accelerating device, and / or collection means. The accelerating device is configured to accelerate the analyte substance (optionally the liquid or solid analyte substance) towards the collision structure for collision therewith to scatter the analyte substance and thereby induce ionisation of the analyte substance by triboelectric charge transfer. Optionally, the collection means is provided for guiding the ionised analyte substance to the ion detecting device.

[0016] In a second aspect, a projectile forthe ion source is provided. The projectile includes a matrix configured to contain the analyte substance and configured to be accelerated by the accelerating device.

[0017] In a third aspect, an ion source assembly is provided which includes the ion source and the projectile.

[0018] In a fourth aspect, an ion detecting device including the ion source assembly is provided.

[0019] In a fifth aspect, a method for generating ions of an analyte substance (optionally a liquid or solid analyte substance) for an ion detecting device is provided. The method comprises the steps of accelerating the analyte substance (optionally a liquid or solid analyte substance); colliding the analyte substance with a collision substrate to scatter the analyte substance and thereby induce ionisation of the analyte substance by triboelectric charge transfer; and / or guiding the ionised analyte substance to the ion detecting device.

[0020] The ion source facilitates ionisation of an analyte substance which may be electrically neutral. For example, the triboelectric charge transfer can be used for analyte substances that may not be ionised or not to a desired degree using commonly known techniques, for example the electrospray ionisation source. Further, the ion source can provide high throughput rates because it is possible to shoot the analyte substance against the collision structure at a high rate. In this way, many different analyte substances can be ionised one after the other.

[0021] Further, the ion source may ionize the liquid analyte substance without generating a gas of the liquid or solid analyte. This means that the ion source does not require the liquid or solid analyte to transform in a gas for the ionisation of the analyte substance. Rather, the liquid or solid analyte substance can be directly used, e.g. without a step of gasifying the liquid or solid analyte substance. The liquid or solid analyte substance may be input into the ion source. The ion source may be configured to work only with a liquid or solid analyte substance as an input.

[0022] The ion detecting device can be any means and / or device with which ions can be detected, measured, and / or analysed. For example, the ion detecting device can be a mass spectrometer. The ion source may be attached to the mass spectrometer for providing ions to be analysed by the mass spectrometer. In 8628380

[0023] 3 more general, the ion source as described herein may be directly or indirectly connected to the ion detecting device. The ions generated by the ion source can be detected, measured, and / or analysed by the ion detecting device.

[0024] The ion source may be removably or permanently connected to the ion detecting device. For example, the ion source can be used for different types or different instruments of the ion detecting device.

[0025] The analyte substance may be electrically neutral. In this case, the ion source can ionise the electrically neutral analyte substance. Alternatively, the analyte substance may be electrically charged, e.g. already includes ions. In this case, the ion source may increase the electrical charge of the analyte substance and / or ionise further components of the analyte substance.

[0026] The analyte substance may be a sample that a user wishes to detect, analyse, and / or measure, e.g. using the ion detecting device. The analyte substance may include one or more different components, e.g. the molecules to be analysed and a carrier medium, e.g. a liquid or solid matrix in which the molecules to be analysed are desolved or immersed. Further, the analyte substance may be a sample that is commonly analysed using a mass spectrometer.

[0027] The analyte substance may be solid (e.g. a powder) and / or liquid. The analyte substance may not be a gas or vapour. The analyte substance may include molecules, particles, and / or atoms that are analysed by the ion detecting device. The ion source may be used instead of or in addition to commonly known techniques for ionising the analyte substance, e.g. by bombarding the analyte substance with a beam of electrons and / or by an electrospray ionisation source.

[0028] As commonly known, the triboelectric effect (also known as triboelectricity, triboelectric charging, triboelectrification, or tribocharging) refers to an electric charge transfer between two objects when they contact or slide against each other. The triboelectric effect is ubiquitous, and occurs with differing amounts of charge transfer (tribocharge) for all solid materials. It is assumed that tribocharging can occur between combinations of solids, liquids and gases, for example a liquid flowing in a solid tube or an aircraft flying through air.

[0029] For the present invention, the triboelectric charge transfer occurs upon impact on the collision structure. Thereby, the analyte substance contacts or slides against the collision structure which may generate the triboelectric charge transfer between the collision structure and the analyte substance. An alternative or additional mechanism is that, upon impact, the analyte substance contacts or slides against itself leading to a tribo- electrical charge transfer between the analyte substance itself. For example, if a droplet or a small particle of the analyte substance is smashed against the collision structure, the effects of the impact onto the collision structure generates internal friction and / or movement of parts of the droplet or the party to against each other which results in the triboelectric charge transfer.

[0030] In this way, the analyte substance can be analysed without applying external electrodes to the analyte substance, for example as done when subjected analyte substance to a beam of electrodes. Rather, the effects used with the ion source internally transfer charges which may result in less structural damages and / or changes of the molecular structure of the analyte substance. 8628380

[0031] 4

[0032] The collision structure may be any mechanical means onto which the analyte substance impacts. The collision structure may be made from metal, ceramic, glass, and / or plastic materials. The collision structure may be made from materials that are vacuum compatible material, easy to clean and / or hard. The collision structure may be configured to withstand the impact of the analyte substance, for example many impacts of the analyte substance. Thus, the collision structure requires a minimum of structural stability. The collision structure may be electrically neutral and / or may not be subjected to an electrical potential.

[0033] The collision structure may include self-cleaning properties. For example, the collision structure includes a low degree of friction and / or non-stick properties such that material that impacts onto the collision structure is less likely to stick to the collision structure.

[0034] The accelerating device can include any means with which the analyte substance can be accelerated towards the collision structure such that the analyte substance impacts onto the collision structure. For example, the accelerating device faces collision structure.

[0035] The accelerating device may be configured to accelerate drops and / or droplets of the liquid analyte substance. Further, the accelerating device may be configured to accelerate particles and / or powder which is made of the analyte substance and / or includes the analyte substance. For example, the accelerating device uses gas pressure for accelerating the analyte substance. However, it is also possible that the accelerating device uses electrical, magnetic and / or other types of ferees for accelerating the analyte substance.

[0036] The accelerating device may be configured to accelerate the analyte substance to achieve velocities of more than 50 m / s, 100 m / s, 200 m / s, 300 m / s, or 400 m / s (and less than 1000 m / s) prior to impact onto the collision structure. In other words, the accelerating device may accelerate the analyte substance such that it impacts onto the collision structure having velocities of more than 50 m / s, 100 m / s, 200 m / s, 300 m / s, or 400 m / s (and less than 1000 m / s). It is assumed that the triboelectric charge transfer increases with increased impact velocities. In other words, the yield of ionisation may be increased by increasing the acceleration and, therefore, the velocity of the analyte substance.

[0037] The yield of ionisation is assumed to depend on the material of the analyte substance and / or the material of the collision structure. Thus, for a given analyte substance or class of analyte substances, the yield of ionisation may be increased by selecting an appropriate material for the collision structure. However, it has been shown that the triboelectric charge transfer occurs for a variety of analyte substances or classes of analyte substances by using the same material for the collision structure. This effect allows to use a single collision structure for many different types of analyte substances or classes of analyte substances.

[0038] The collection means may be provided for collecting and / or guiding the analyte substance that impacted onto the collision structure and scattered back from collision structure. The collection means may be directly or indirectly connected to the ion detecting device. The collection means is for example configured to only guide the ions that are ionised by the triboelectric of charge transfer towards the ion detecting device. As described in more detail below, the collection device may include a pump for sucking 8628380

[0039] 5 the ions to the ion detecting device and / or electrodes for applying an electrical force to the ionised analyte substance.

[0040] Further, it is expected that the yield of ionisation is higher if a solid material collides with the collision structure. This is potentially because the friction during the impact of the solid material onto the collision structure is higher compared to a liquid material. The increased friction may be the cause for increased triboelectric charge transfer. Thus, the analyte substance may be absorbed and / or contained in a solid matrix and the solid matrix is accelerated by the accelerating device.

[0041] In an optional embodiment, the accelerating device is configured to accelerate a projectile containing the analyte substance.

[0042] In an optional embodiment, the matrix of the projectile is configured to absorb the liquid analyte substance.

[0043] In an optional embodiment, the matrix is made from a tribo-chargeable material for inducing ionisation of the analyte substance by triboelectric charge transfer between the tribo-chargeable material of the matrix and / or between the tribo-chargeable material and the analyte substance.

[0044] In an alternative example, the projectile can be completely made from the analyte substance or can be made from the analyte substance to a high degree. For example, the projectile mainly includes the analyte substance and some binder and / or adhesive material for binding the analyte substance material together. For example, the projectile includes 90%, 95%, or 99% of the analyte substance compared to the mass of the entire projectile. In this case, the analyte substance may be tribo-chargeable.

[0045] As outlined above, the projectile can also include a matrix that contains the analyte substance. For example, the matrix provides a shell within which the solid and / or liquid analyte substance material is contained. Alternatively, the matrix is made from an absorbable material which is configured to absorb the liquid analyte substance. The matrix material can be made from a tribo-chargeable material which can be understood as any material that exhibits the triboelectric charge transfer. The weight of the analyte substance may be less than 1%, 3 %, 5 %, 10 %, 20%, 30 %, 40 %, 50 %, or 60 % of the weight of the entire projectile.

[0046] The tribo-chargeable matrix may be provided for increasing the triboelectric charge transfer, for example in cases in which the yield of the triboelectric charge transfer by the analyte substance itself is not as high as desired. Further, the matrix may be used for simplifying the acceleration of the analyte substance. For example, it may be experimentally challenging accelerating a liquid analyte substance to a sufficient degree and / or to provide a high repetition rate for the plurality of analyte substances. In this case, the matrix of the projectile can be used as carrier for the liquid analyte substance.

[0047] The projectile and / or the matrix of the projectile may have sufficient rigidity such that the projectile can be accelerated to the desired velocity. On the other hand, the rigidity of the projectile and / or the matrix is sufficiently low such that it is scattered and / or destroyed upon impact on the collision structure. In this case, upon impact on the collision structure, the projectile scatters in many pieces and / or particles which 8628380

[0048] 6 slide against each other during the scattering process, e.g. during the deformation of the projectile upon impact onto the collision structure.

[0049] The matrix material may include 3-Nitrobenzonitrile and / or any material that is used as a matrix for Matrix- assisted Laser Desorption / lonization (MALDI). The MALDI matrix may consist of crystallized molecules, of which the three most commonly used are sinapinic acid, a-cyano-4-hydroxycinnamic acid (a-CHCA, alpha-cyano or alpha-matrix) and 2,5-dihydroxybenzoic acid (DHB). A solution of one of these molecules is made, often in a mixture of highly purified water and an organic solvent such as acetonitrile (ACN) or ethanol. A counter ion source such as trifluoroacetic acid (TFA) is usually added to generate the [M+H] ions. A further example of a matrix-solution would be 20 mg / mL sinapinic acid in ACN:water:TFA (50:50:0.1).

[0050] The triboelectric charge transfer may occur during this scattering process, i.e. when the projectile and / or the matrix is deformed and then splits up in many different particles and / or pieces. The triboelectric charge transfer may occur between different particles and / or pieces, e.g. when different particles and / or pieces of the projectile move relative to each other. The triboelectric of charge transfer generated in this way made then ionise the analyte substance. In other words, tribo-electrical charge transfer is generated by the material of the matrix. The generated charge is then transferred to the analyte substance leading to the ionisation of the analyte substance. Thus, in this case, the material of the matrix provides the electrical charge (by triboelectric charge transfer). The generated charges are then transferred to analyte substance, for example because the analyte substance is in contact with the charged pieces and / or particles the matrix material. The charge transfer between the charged pieces and / or particles to the analyte substance may occur because the analyte substance is absorbed by the matrix material or in contact with the matrix material.

[0051] Another possible mechanism of the triboelectric charge transfer can occur between the matrix material and collision structure. In this case, upon impact, the matrix material slides along the collision structure resulting in a charge transfer between a collision structure and the scattered pieces and / or particles of the matrix material. Again, the charges generated in this way are then transferred to the analyte substance.

[0052] A further possible triboelectric charge transfer can occur between the analyte substance itself. Upon impact, parts and / or pieces of the analyte substances can slide against each other resulting in a direct triboelectric charge transfer. Of course, the ionisation of the analyte substance may include one or more of the triboelectric charge transfer mechanisms described herein. The triboelectric charge transfers that occur in a particular ionisation process depend on the material of the matrix, the material of the collision structure, and / or on the material of the analyte substance.

[0053] The material of the matrix may be porous for absorbing a liquid analyte substance. The material of the matrix may be hydrophilic in case of a hydrophilic analyte substance. The material of the matrix baby file can case of a lipophilic analyte substance. 8628380

[0054] 7

[0055] The projectile may have the shape of a ball and / or may have a diameter more than 0.01 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, or 0.6 mm and / or less than 0.8 mm, 0.9 mm, 1 .0 mm, 1 .5 mm, or 2 mm.

[0056] The material of the matrix may be chemically inert such that the matrix does not chemically alter or change the analyte substance when the analyte substances is immersed in the matrix. The provision of matrix may facilitate the preparation of a plurality of projectiles prior to the ionisation of the analyte substance. For example, a plurality of matrixes is provided and each matrix is used to carry a different analyte substance. In this way, a plurality of different analyte substances can be ionised and / or analysed. Further, it is possible to store the analyte substances in the projectiles. For example, the preparation of the projectiles can be made remote from the ion source, e.g. in a different laboratory.

[0057] An exemplary method for producing projectile includes providing a matrix, optionally a plurality of matrixes, and adding the analyte substance to the matrix, optionally a plurality of different analyte substances to respective matrixes. This may be implemented by dropping one or more droplets of the analyte substance on to a respective matrix. Alternatively, the matrix may be soaked in the liquid analyte solution.

[0058] The plurality of matrixes may each have the same shape and / or size and / or may be made from the same material. In this case, the plurality of matrixes can be mass produced and applied for many different types of analyte substances. Of course, it is also possible that the plurality of matrixes each have to same shape and / or size but differ in their material of the matrix. For example, a first matrix material is used for hydrophilic analyte substances and a second matrix material may be used for a lipophilic analyte substances.

[0059] In an optional embodiment, the accelerating device includes a gas pressure means configured to generate a gas pressure difference between a start location and the collision structure. Optionally, the start location is a location at which the projectile and / or the analyte substance are to be located prior to the projectile being accelerated towards the collision structure.

[0060] With this optional embodiment, the analyte substance and / or the projectile are accelerated by a gas pressure. For example, there is a positive gas pressure at the start location which accelerates the analyte substance and / or the projectile towards the collision structure. Alternatively or additionally, there is a negative pressure at the collision structure which sucks the projectile and / or the analyte substance towards the collision surface.

[0061] Accelerating the projectile and / or the analyte substance using gas pressure (e.g. a gas pressure difference) can provide high acceleration and, therefore, high velocities prior to impact on to the collision structure. The start location may be the location at which the projectile and / or the analyte substance is placed for being subsequently accelerated by the accelerating device. If no gas pressure is provided by the accelerating device, the projectile and / or the analyte substance may remain at the start location. In other words, holding means may be provided at the start location which removably fixes the projectile 8628380

[0062] 8 and / or the analyte substance at the start location. For example, the holding means includes a recess or cavity in which the projectile and / or a liquid analyte substance is placed.

[0063] The gas pressure and / or the gas pressure difference may be provided by a gas pump. Alternatively, the gas pressure and / or gas pressure difference can be provided by a gas pressure source, such as a cylinder for containing a pressurized gas. For example, the accelerating device may be configured similar to an air gun which is a gun that uses energy from compressed air or other gases that are mechanically pressurized and then released to propel and accelerate projectiles and / or the analyte substance.

[0064] In an optional embodiment, the accelerating device includes a pipe, a gas-tight chamber, and / or a gas pump. Optionally, the pipe contains the start location. Further optionally, the projectile is configured to be accelerated from the start point along a longitudinal axis of the pipe. In an embodiment, the longitudinal axis is directed towards the collision surface. Optionally, the pipe extends through a wall of the chamber. Further optionally, the gas pump is configured to generate a negative pressure in the chamber for sucking the projectile from the start location into the chamber.

[0065] The pipe may be an elongate component housing an elongate cavity. The pipe may be made from metal, ceramic, and / or plastic material. A diameter and / or shape of the cavity may be aligned with a diameter and / or shape, respectively, of the projectile. For example, the projectile may tightly fit into the cavity of the pipe such that little or no gas can flow around the projectile arranged within the cavity of the pipe. In other words, the projectile may tightly seal the cavity of the pipe such that a gas pressure difference between either side of the projectile within the cavity results in an acceleration of the projectile within the cavity of the pipe. The pipe may be considered a barrel or a capillary, optionally similar to capillaries used with ion detecting devices and / or mass spectrometers.

[0066] The gas-tight chamber may be gas-tight except for distinctively provided openings. For example, the pipe provides an opening to the gas-tight chamber. The pipe may allow gas exchange between the inside of the gas-tight chamber and its surroundings. For example, the gas pump may be configured to generate a negative pressure or a vacuum inside the gas-tight chamber. The gas pump may include one or more commonly known pumps for creating a negative pressure (e.g. a pressure lower than the atmospheric pressure) and / or vacuum inside the gas-tight chamber. For example, the pressure in the gas-tight chamber is between 500 mbar and 0.1 mbar, optionally between 300 mbar and 1 mbar, such as 200 mbar, 100 mbar, 50 mbar, 25 mbar, 10 mbar, or 5 mbar.

[0067] The start location may be provided with or at the pipe. For example, the start location may correspond to an open end of the pipe that is not arranged inside the gas-tight chamber. For example, the other end of the pipe is arranged inside the gas-tight chamber. In an alternative embodiment, the pipe includes a cutout, aperture, and / or opening at which the projectile and / or the analyte substance can be placed. In this case, the cutout, aperture, and / or opening may correspond to the start location.

[0068] The elongate cavity and / or the pipe may define a longitudinal axis along which the projectile and / or the analyte substance is accelerated. The pipe may correspond to the barrel or bore of an (air) gun. The pipe and / or its longitudinal axis is orientated to be directed towards the collision structure. In this way, the 8628380

[0069] 9 projectile and / or the analyte substance is accelerated towards the collision structure such that the projectile and / or the analyte substance collides with the collision structure.

[0070] In one example, the pipe provides a means for guiding the projectile and / or the analyte substance through a wall of the gas-tight chamber. The collision structure may be arranged inside the gas-tight chamber.

[0071] In one embodiment, the negative pressure or vacuum inside the gas-tight chamber may provide a pressure difference for accelerating the projectile and / or the analyte substance. For example, the (open) end of the pipe that is not arranged inside the gas-tight chamber may be exposed to atmospheric pressure or to a pressure source that provides a positive pressure (e.g. a pressure higher than the atmospheric pressure). In this way, the projectile and / or the analyte substance is sucked through the pipe into the gas-tight chamber and collides with the collision structure.

[0072] In this way, the gas pressure difference by providing a negative pressure inside the gas-tight chamber can be provided in a simple way. Further, repetitive accelerations of different projectiles and / or analyte substances can be provided shortly one after another because the volume of the gas chamber may be significantly higher than the volume of the cavity of the pipe such that the acceleration of a single projectile and / or analyte substance may not significantly alter the pressure within the gas-tight chamber. Thus, little or no time needs to pass before the next projectile and / or analyte substance can be accelerated.

[0073] In an optional embodiment, the ion source further comprises a liquid feeding means configured to supply the liquid analyte substance to the start location.

[0074] The analyte substance may be a liquid analyte substance with this embodiment. The liquid feeding means can be any device that can supply a liquid to the start location. In a simple embodiment, the liquid feeding means may include a hose or capillary that continuously or intermittently supplies the liquid analyte substance to the start location, e.g. an open end of the pipe.

[0075] In another embodiment, the liquid feeding means is configured to place a drop or droplet of the liquid analyte substance at the start location. For example, the liquid feeding means is a pipette that can be attached to the ion source in such a way that the pipette places droplets at the start location, for example the open end of the pipe. However, other known means for supplying a liquid or droplets of the liquid to a particular location can be used for the liquid feeding means.

[0076] When the liquid analyte substance accelerates through the pipe, the liquid analyte substance can freeze due to the pressure difference between the start location and the collision structure. The freezing of the liquid analyte substance is more pronounced the lower the pressure in the gas-tight chamber is. Thus, even if a liquid analyte substance is inserted into the ion source, a solid, the frozen liquids substance, collides with the collision structure. As outlined above, the freezing of the liquid analyte substance may increase the triboelectric charge transfer. The provision of the accelerating means as a means for generating a pressure difference therefore allows using a liquid analyte substance while providing the triboelectric charge transfer usually associated with a solid material. 8628380

[0077] 10

[0078] Further, the provision of a liquid analyte substance is a simple way to increase throughput, for example by continuing supplying the liquid analyte substance or repetitive generation of a droplet of liquid substance to be inserted into the ion source.

[0079] The accelerating device may further include a cooling device for cooling the pipe. The pipe may be made from a material with high thermal conductivity, such as metal. The cooling device cools the pipe which in turn promotes freezing of the liquid analyte substance. The pipe may be moisture-tight to prevent the formation of frozen analyte substance inside the pipe.

[0080] In an optional embodiment, the accelerating device further includes a projectile storage means for storing a plurality of projectiles.

[0081] The projectile storage means is another way of increasing throughput on the processing rate of the ion source. For example, a plurality of projectiles that contain different analyte substances can be stored and / or handled using the projectile storing means. The projectile storing means may be linked or connected to the accelerating device. This may allow that all projectile stored in the projectile storing means can be analysed one after the other in a single preparation step.

[0082] In an optional embodiment, the projectile storing means is configured to place each projectile (stored in the projectile storing means) at the start location one after the other.

[0083] The projectile storing means may be configured to align the projectiles in a line, wherein optionally each projectile contacts the next projectile in the line. For example, the projectile storing means may include a ramp or tube on or in which the projectiles are lined up. An open end of the ramp or tube may face the start location and gravity pushes the projectiles to the start location one after the other. Alternatively or additionally, a biasing means is provided for pushing the projectiles to the start location. For example, if the projectile at the start location has been accelerated towards the collision structure by the accelerating device, the next projectile in the line of projectiles is moved to the start location by the projectile storing means.

[0084] The above-described examples of the projectile storage means have the advantage that no other components are required for moving the projectiles to the start location. The biasing means and / or the gravity actuates the projectiles.

[0085] In an optional embodiment, the projectile storage means includes a projectile array and an actuator configured to move the projectile array. Optionally, the projectile array includes a plurality of cavities, each cavity being configured to hold a single projectile. Further optionally, the actuator is configured to position the projectile array such that the cavity is located at the start position.

[0086] The projectile array may include a grid or pattern (of cavities) for supporting or holding the projectiles. The cavity may include a through-hole, a recess, a cutout, or the like. The shape and / or the size of the cavity may be aligned with the shape and / or size, respectively, of the projectile. For example, the projectile may be slightly larger than the size of the cavity such that the projectile is held in the cavity by friction. Of course, the force holding the projectiles in the projectile array is (significantly) smaller than the force to which the projectiles are subjected during acceleration (e.g. by the accelerating device). 8628380

[0087] 11

[0088] The actuator may include one or more motors, such as electrical motors, for moving the projectile array in one, two, or three dimensions. For example, the projectile array is coupled or connected to the actuator. The actuator may be configured to position each cavity of the projectile array at the start position. In this way, each projectile stored in the projectile array can be placed at the start position one after the other.

[0089] A controller may be provided for controlling the actuator so as to automatically move the projectile array along a pattern such that each cavity of the projectile array is placed at the start location one after the other. In this way, a plurality of measurement can be conducted automatically.

[0090] In an optional embodiment, the projectile storage means is removably attachable to the ion source.

[0091] For example, the projectile array can be removably coupled or connected to the actuator. The projectile storage means may be removed from the ion source for filling the projectile storage means with the projectiles. This may simplify the insertion of the projectiles into the projectile storage means. Further, it is possible to insert the projectiles into the projectile storage means at the location different to a location where the ion source is located. For example, the projectiles are manufactured and / or provided with the analyte substance in a laboratory that is in a different location with regard to location where the ion source is located. In a words, the preparation of the analyte substance for the measurement (e.g. adding the analyte substance to the matrix) and the measurement of the analyte substance can be spatially separated. Further, it may be possible to transport a plurality of projectiles using the projectile storing means, e.g. the projectile array.

[0092] In an optional embodiment, the accelerating device further comprises a closure device for selectively closing the pipe in at least one closed position, optionally in gas-tight matter, and opening the pipe to the chamber in at least one open position.

[0093] In this way, the projectile and / or the analyte substance can be selectively accelerated by bringing the closure device from the closed position to the open position. Thus, even if a negative pressure is maintained in the gas-tight chamber, the closure device provides for selectively opening and closing the pipe and, therefore, provides for a mechanism for selectively accelerating the projectile and / or the analyte substance.

[0094] In the closed position, the pipe may be sealed and / or closed in a gas-tight manner. For example, the negative pressure of the gas-tight chamber is not present at the start location in the closed position. For example, atmospheric pressure is present at the start location when the closure device is in the closed position. However, if the closure device is in the open position, the negative pressure inside the gas-tight chamber may also be present at the start location. In other words, there is gas exchange between the inside of the gas-tight chamber and the outside of the gas-tight chamber through the pipe when the closure device is in the open position. Conversely, when the closure device is in the closed position, there is no gas exchange between the inside of the gas-tight chamber and the outside of the gas-tight chamber through the pipe.

[0095] The closure device may have one or more different open positions and / or one or more different closed positions. Each open position and / or closed position have the technical effect as described above. 8628380

[0096] 12

[0097] In an optional embodiment, the closure device includes a disk and a motor for rotating the disk between the at least one open position and the at least one closed position. Optionally, the disk includes at least one through-hole. Further optionally, the motor is configured to position the disk such that the at least one through-hole aligns with the pipe in the open position and the at least one through-hole is offset from the pipe in the closed position.

[0098] Each through-hole of the disc may correspond to an open position. Each part of the disc offset from the through-hole may correspond to a closed position. For example, the through-holes are spaced from each other along a circumferential direction of the disc. Optionally, the through holes are equally spaced from each other. The diameter of the through-holes may correspond to the diameter of the cavity of the pipe.

[0099] The pipe may include an intersection or cutout at which the disc is located. Thus, in the open position, a through-hole of the disc is aligned with the cavity of the pipe. In the closed position, any through-hole of the disc is offset from the cavity of the pipe such that the disc blocks the cavity of the pipe.

[0100] The disc may be moved from the open position to the closed position and vice versa by rotating the disc. The motor may be used for rotating the disc. Of course, other means for closing and opening gas exchange through the pipe are possible. For example, a strip having a through-hole may be linearly moved by a motor for moving the strip between the open position (in which the through-hole of the strip is aligned with the cavity of the pipe) and the closed position (in which the through-hole of the strip is offset to the cavity of the pipe).

[0101] The motor may be in data communication with the controller or a separate controller, optionally for automatically controlling the disc between the open position and the closed position. The controller may coordinate the movement of the projectile storage means, e.g. the projectile array, and the closure device. For example, the controller controls the projectile storage means such that a new projectile is placed at the start location. Once this operation is completed, the controller controls the closure device such that it is moved from the closed position to the open position. Thereafter, the projectile is accelerated and collides with the collision structure. Then, the above-described process is repeated.

[0102] Of course, the closure device may also work in cooperation with the liquid feeding means. In this case, the liquid feeding means places a droplet of the liquid analyte substance at the start location. Thereafter, the closure device is controlled to be moved from the closed position to the open position for starting the acceleration of the liquid analyte substance. Alternatively, in case the liquid feeding means continuously supplies liquid analyte substance to the start location, the closure device can be used for controlling the time windows during which the liquid analyte substance is accelerated. In this way, small amounts of the liquid analyte substance can be repetitively accelerated for the collision with the collision structure.

[0103] In an optional embodiment, the collision structure is provided by a solid block or a mesh.

[0104] The collision structure can be made from a metal material, ceramic, and / or plastic material. The collision structure may be subjected to surface treatment such that the collision structure has non-stick properties. This may be helpful for avoiding and / or reducing the agglomeration and / or accumulation of residues of the analyte substance and / or the matrix material of the projectile on the coll. 8628380

[0105] 13

[0106] In case of a solid block for the collision structure, the analyte substance may be scattered back from the collision surface relative to the longitudinal axis. In case of a mesh material for the collision structure, the scattered analyte substance may fly substantially in the same direction as the longitudinal axis. In other words, the analyte substance may fly through the collision structure made of a mesh.

[0107] In an optional embodiment, the ion source further comprises a vibration means configured to vibrate the collision structure for removing residues from the collision structure.

[0108] The vibration means may include any means or component that is configured to vibrate and / or oscillate the collision structure. For example, the vibration means includes one or more piezos for oscillating the collision structure at high frequencies. The vibration or oscillation of the collision structure may lead to a removal or reduction of any residues of the analyte substance and / or the matrix material of the projectiles from the collision structure. In this way, the collision structure can be cleaned without accessing the collision structure. For example, the gas-tight chamber in which the collision structure may be arranged, does not need to be opened for cleaning the collision structure. This is particularly helpful if a plurality of projectiles is fired towards the collision structure, for example using the projectile storage means.

[0109] In an optional embodiment, the collection means includes a collection chamber having an outlet configured to be connected to the ion detecting device. Optionally, the outlet is configured to be subjected to a negative pressure.

[0110] The collection chamber may be identical to and / or may be provided by the chamber of the accelerating device. The collection chamber may be gas-tight and / or it is possible to generate a low-pressure and / or vacuum inside the collection chamber. The collection chamber may entirely surround the collision structure. In particular, the collection chamber is configured to gather and / or collect the particles, drops and / or other particular matter that is scattered from the collision surface.

[0111] The outlet may include a through-hole and / or opening in the collection chamber and / or may provide a gas connection to the ion detecting device. For example, the outlet of the collection chamber is connected to a heated capillary of the ion detecting device. The outlet of the collection chamber may be in gascommunication with a low-pressure and / or vacuum of the ion detecting device. The outlet may be provided in a wall of the collection chamber.

[0112] In this way, the ionised analyte substance may be sucked into the ion detecting device through the outlet of the collection chamber. In other words, the collection of the ionised analyte substance is at least partly provided by the application of a negative pressure via the outlet of the collection chamber. This type of collection of the ionised analyte substance may take advantage of the higher mobility of the ionised analyte substance compared to the mobility of the matrix material.

[0113] In an optional embodiment, the collection means includes at least one electrode for generating an electrical field interacting with the ionised analyte substance. Optionally, the at least one electrode is arranged and / or shaped to actuate the ionised analyte substance to the outlet.

[0114] The one or more electrodes may be electrically connected to a voltage source, for example to the same or different poles of the voltage source. The electrodes are configured to provide an electric field for 8628380

[0115] 14 generating a force for accelerating the ionised analyte substance. For example, one or more of the electrodes may be provided for repelling the ionised analyte substance and / or one or more of the electrodes may be provided for attracting the ionised analyte substance. In this way, the one or more electrodes may be provided for generating an electric field that guides that the ionised analyte substance to and / or towards the outlet of the collection chamber.

[0116] The one or more electrodes may be provided inside the collection chamber and / or are connected to one or more walls of the collection chamber. Further, it is possible that parts or entire walls of the collection chamber may provide the electrodes. The one or more electrodes may have shapes and / or sizes adapted to provide the electrical field as outlined above.

[0117] One or more of the electrodes may be provided in a region of the collection chamber into which the analyte substance and / or the projectile is scattered by the collection surface. In this case, the one or more electrodes may be provided for decelerating the ionised analyte substance that is scattered from the collection surface. Further, one or more electrodes may be provided for accelerating the ionised analyte substance towards the outlet of the collection chamber. Attracting and / or repelling forces may be provided by the one or more electrodes required.

[0118] The collection chamber may also be provided with a gas inlet. A continuous flow of gas may be inserted into the collection chamber via the gas inlet. This may provide a gas flow between the gas inlet and the outlet. This gas flow may be used for guiding the ionised analyte substance towards the outlet.

[0119] The invention may be briefly described as follows:

[0120] The invention is using the phenomenon of tribocharging for generating ionisation which is also known as triboionization. The triboionization can occur upon a projectile carrying sample (an example of the analyte substance) impacts on a baffle which is an example of the collision structure. The invention may provide a more efficient way of achieving high throughput in mass spectrometry compared to electrospray ionisation, as many samples or analyte substances can be analysed in short time with no carry over of material between samples.

[0121] In an exemplary embodiment of the invention, a projectile in a form of a porous ball, for example made from 3-Nitrobenzonitrile, is formed. This projectile for ionisation of the analyte substance could be mass produced and delivered to the laboratory for direct use. The analyte substance can be deposited on the projectile creating the analyte substance-soaked projectile. The deposition could be manual using a pipetting method. The analyte substance could be delivered from a liquid chromatography (LC) tube, for example each projectile, e.g. a ball, would be exposed to the LC tube liquid output in a moment when LC detects a corresponding signal from its detector, for example UV detector. This could be continuous process of exposing projectiles to LC sample liquid output in defined time intervals. The ready projectile may be stored in the projectile storage means (such as a holder) having an array of distributed tubular openings.

[0122] The projectile storage means can be inserted in the actuator (such as a two-axis moving device), exposing each tubular opening (an example of the cavity) with the projectile to the gas flow of the pipe 8628380

[0123] 15

[0124] (e.g. a barrel). To assure synchronisation of projectile ejection into low pressure ionisation chamber, a spinning disk may be provided. The disk has openings and is synchronised with the actuator of the projectile array. The synchronisation assures that projectile ejection is in the moment when tubular opening of the projectile array is aligned with the pipe.

[0125] The pressure difference between both ends of the pipe could be provided by atmospheric pressure at the one end and vacuum pressure at the other end, for example 200, 100, 50, 25, 10, 5 mbar, such that the projectile can achieve high velocity of more than 100 m / s, 200 m / s, 300 m / s. In the low-pressure chamber, the ejected projectile collides with the collection structure. The crash of the projectile can create a tribocharging effect leading to triboionization and ejecting ions of the analyte substance. The ions’ flow and residence time in the chamber can be controlled by guiding electrodes, pumping speed, and / or additionally separated gas intake regulated by a mass flow controller. The guiding electrodes can help to reach the inlet of the ion detecting device, for example the heated capillary, where remaining droplets from ion source are desolved, often referred to as desolvation line. From there, the mass spectrometer measurement process can be same as for the standard ion source like electrospray ionisation.

[0126] The above-described optional features, characteristics, and / or technical effects of the ion source, the projectile, the ion source assembly, and / or the ion detecting device equally apply to the method for generating ions of an analyte substance for an ion detecting device.

[0127] The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0128] Summary of the Figures

[0129] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which:

[0130] Figure 1 shows a schematic view of an example of a mass spectrometer including an electrospray ionisation source of the prior art.

[0131] Figure 2 shows a schematic view of a first embodiment of an ion source and some components of the mass spectrometer of Figure 1 .

[0132] Figure 3 shows a schematic view of a second embodiment of the ion source and some components of the mass spectrometer of Figure 1 .

[0133] Figure 4 shows a schematic view of two steps of preparing a projectile that can be used with the ion source of Figure 2.

[0134] Figure 5 shows two photographs (upper row) and a schematic drawing of an experimental setup for demonstrating a triboelectric charge transfer used with the ion sources of Figures 2 and 3.

[0135] Figure 6 shows mass spectrums for comparing ionisation of Myoblobin using an electrospray ionisation source of Figure 1 and the ion source of Figure 2. 8628380

[0136] 16

[0137] Figure 7 shows photographs of an experimental setup for demonstrating triboluminescence.

[0138] Figure 8 shows a block diagram showing steps of a method for generating ions of an analyte substance.

[0139] Detailed Description of the Invention

[0140] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0141] Figure 1 refers to an example of the prior art that is a single quadrupole mass spectrometer (MS) 100. Ions are generated by an electrospray ionisation (ESI) source 102 in atmospheric pressure conditions. From the electrospray ionisation environment, ions are sucked into vacuum, for example by a heated capillary, where remaining droplets from the electrospray ionisation source 102 are desolved, which may be referred as a desolvation line (DL) 104. The ions exit the desolvation line 104 with supersonic speed and enter a vacuum region of the mass spectrometer 100, where the ions are collected and focused for further transfer. This is done, for example by a quadrupole electrode referred as Q-array 106. Thereafter, the ions are moved to focusing optics 108 and then to a quadrupole mass analyser 110 that filters ions with selected mass to charge ratio. Filtered ions are detected by an ion detector 112 which detects only ions and ignores neutral atoms and / or molecules.

[0142] This particular example of the mass spectrometer 100 has the drawback that some droplets generated by electrospray ionisation source 102 are not changed into ions. Thus, no non-ionised atoms and / or molecules of the sample pass through the entire mass spectrometer 100 without interaction with its elements. In particular, the ion detector 112 is of type that detect only ions.

[0143] Figure 2 shows an ion detecting device 140 which includes an ion detecting assembly 141 and the mass spectrometer 100 of Figure 1 (without the electrospray ionisation source 102). The ion detecting assembly 141 includes an ion source 142 can be used instead of the electrospray ionisation source 102. The ion detecting assembly 141 further includes an analyte-soaked projectile 153.

[0144] The ion source 142 includes an accelerating device 144, a collision structure 146, and / or collection means 148. The accelerating device 144 is configured to accelerate the analyte-soaked projectile 153 such that the analyte-soaked projectile 153 collides with the collision structure 146. Upon impact, the analyte-soaked projectile 153 scatters into various particles and / or pieces resulting in a triboelectric charge transfer which ionises an analyte substance with which their projectile 153 is soaked. The ionised analyte substance is collected by the collection means 148 and forwarded to the mass spectrometer 100.

[0145] The accelerating device 144 includes a projectile storing means 156 storing and / or holding a plurality of the analyte-soaked projectiles 153 and / or a gas pressure means 155 for accelerating the analyte-soaked projectiles 153. The gas pressure means 155 may include a pipe 158, a gas-tight chamber 168, a closure device 160, and / or a gas pump (not shown in the drawings). 8628380

[0146] 17

[0147] The pipe 158 may be a capillary and / or a barrel in which the analyte-soaked projectiles 153 are accelerated. For example, the analyte-soaked projectiles 153 may tightly fit into the pipe 158 such that a pressure difference between either side of the analyte-soaked projectiles 153 can built up inside the pipe 158. The pipe 158 provides for a start location 158a at which the analyte-soaked projectile 153 can be placed prior to acceleration by the accelerating device 144. In the embodiment of Figure 2, the start location 158a may be a cutout in the pipe 158. The analyte-soaked projectile 153 may be placed at the start location 158a by the projectile storing means 156.

[0148] The projectile storing means 156 may include a projectile array 156a and / or an actuator (not shown in Figure 2) for moving the projectile array 156a. The projectile array 156a includes a plurality of cavities, each of which can be filled with the analyte-soaked projectile 153. The cavity may be sized and / or shaped such that the analyte-soaked projectile 153 is tightly fitted into the cavity, for example using friction fit. The analyte-soaked projectile 153 may be held in the cavity when the projectile array 156a is moved. However, the analyte-soaked projectile 153 may be removed from the cavity when the accelerating device 144 accelerates the analyte-soaked projectile 153.

[0149] The projectile array 156a may include one or more rows and / or one or more columns of cavities. The actuator of the projectile storage means 156 may be configured to move each cavity of the projectile array 156a one after the other to the start location 158a. For example, the actuator is configured to move the projectile array 156a into two orthogonal directions.

[0150] The projectile array 156a is shown in Figure 2 in a side view and in a cross-sectional view. Further, the projectile array 156a can be removed from the actuator and / or the accelerating device 144, for example for filling the projectile array 156a with the analyte-soaked projectiles 153. This may be done in a location offset from the location of the accelerating device 144. Of course, it is possible that the projectile array 156a is permanently fixed to the accelerating device 144. In this case, the analyte-soaked projectiles 153 may be inserted into the projectile array 156a on site.

[0151] The closure device 160 includes a motor 161 and / or a disc 162 (the disc 162 is shown in a cross- sectional view and a side view in Figure 2). The closure device 160 is configured to selectively close and open the pipe 158. Optionally, the closure device 160 is configured to selectively open or close the pipe 158 in a gas-tight manner. The disc 162 may include one or more through-holes (e.g. four as shown in Figure 2). The motor 161 is configured to rotate the disc 162 such that one of the through-holes is either aligned with the pipe 158 (an example of the open position) or each is offset from the pipe 158 (an example of the closed position). The cross-sectional view of the disc 162 of Figure 2 shows the open position in which there is gas communication between the chamber 168 and the start position 158a. In a closed position, there is no or little gas communication between the chamber 168 and the start position 158a.

[0152] The gas pump (not shown in Figure 2) is configured to provide a negative pressure (e.g. 200 mbar, 100 mbar, 50 mbar, 25 mbar, 10 mbar, or 5 mbar) inside the chamber 168. When the analyte-soaked projectile 153 is placed at the start position and the closure device 160 is moved to the open position, a gas pressure difference between the open end of the pipe 158 and the chamber 168 is present because 8628380

[0153] 18 the open end of the gas pipe 158 (e.g. the start location 158a) can be subjected to atmospheric pressure. This pressure difference results in an acceleration of the analyte-soaked projectile 153. The analyte- soaked projectile 153 may reach velocities of more than 100 m / s, 200 m / s, or 300 m / s.

[0154] The pipe 158 is oriented such that the analyte-soaked projectile 153 collides with the collision structure 146 which may include a baffle 164. Upon impact, the analyte-soaked projectile 153 scatters into a plurality of particles and / or pieces.

[0155] The analyte-soaked projectile 153 includes a matrix 152 that can contain and / or absorb a liquid analyte substance (see Figure 4). Further, a material of the matrix 152 is tribo-chargeable. Thus, upon impact of the analyte-soaked projectile 153 onto the collision structure 146, triboelectric charge transfer occurs due to the deformation of the matrix 152 during the impact and / or the scattering of the particles from the collision structure 146. This triboelectric charge transfer ionises the analyte substance. In this way, it is possible to ionise an electrically neutral analyte substance.

[0156] The collection means 148 includes a collection chamber and / or one or more electrodes 166. In the embodiment shown in Figure 2, the collection chamber is provided by the chamber 168 of the accelerating device 144. The chamber 168 includes an outlet 168a which is in gas connection to the mass spectrometer 100, optionally in gas connection to the dispersion line 104. In other words, the outlet 168a of the chamber 168 provides the gas communication of the ion source 142 to the mass spectrometer 100. The outlet 168a of the chamber 168 may be subjected to a vacuum and / or a pressure that is smaller than the pressure inside the chamber 168 such that the ionised analyte substance is sucked into the dispersion line 104.

[0157] The electrodes 166 can be connected to a voltage source for providing an electric field that interacts with the ionised analyte substance for guiding the ionised analyte substance to the outlet 168a. For example, the electrodes 166 repel the ionised analyte substance. This may be used for decelerating the ionised analyte substance scattered from the collision structure 146 and / or for providing an accelerating force to move the ionised analyte substance towards the outlet 168a.

[0158] The ion source 142 may further include a vibration means 169 which is configured to vibrate and / or oscillate the collision structure 146, for example the baffle 164. The vibration means 169 may include one or more piezos and / or may vibrate the collision structure 146 at high frequencies. The vibration means 169 may be configured to remove residues and / or agglomerations of the matrix material and / or the analyte substance on the collision structure 146 by means of vibration. Thus, the vibration means 169 may be provided for cleaning the collision structure.

[0159] A method for operating the ion source 142 for ionising analyte substance is described further below in connection with Figure 7.

[0160] Figure 3 shows another embodiment of the ion source 142 (connected to the same mass spectrometer 100 as used with the embodiment of Figure 2) which includes the same optional features, characteristics and / or technical effect as the ion source 142 shown in Figure 2 except for the following differences: 8628380

[0161] 19

[0162] The ion source 142 of Figure 3 does not accelerate the analyte served projectiles 153. Rather, the liquid analyte substance is directly accelerated. To this end, the projectile storage means 156 is replaced by a liquid feeding means 170 which may include any component that is configured to supply small amounts of the liquid analyte substance to the start location 158a. For example, the liquid feeding means 170 places droplets of the liquid analyte substance at the start location 158a. In another example, the liquid feeding means 170 continuously supplies liquid analyte substance to the start location 158a. The amount of the liquid analyte substance that is accelerated can be controlled by the time the closure device 160 is in the open position. The analyte-soaked projectile 153 may not be provided with the ion source 142 of Figure 3.

[0163] The accelerated volume of the liquid analyte substance, for example a droplet, freezers during the acceleration phase due to the rapid decrease in the pressure. Therefore, the frozen droplet may impact onto the collision structure 146. It has been observed that the triboelectric charge transfer is higher with a solid material compared to a liquid material. Thus, the freezing of the liquid analyte substance increases the yield of the triboelectric charge transfer.

[0164] In the example of Figure 3, the triboelectric charge transfer is not based on friction between the matrix material of the analyte-soaked projectile 153. Rather, the triboelectric charge transfer occurs between the frozen bits of pieces of the analyte substance, for example during the formation upon impact.

[0165] Figure 4 shows exemplary steps for preparing the analyte-soaked projectile 153. A ball of matrix material may be provided. The matrix material is tribo-chargeable and / or may include 3-Nitrobenzonitrile and / or any material that is used for as a matrix for Matrix-assisted Laser Desorption / lonization (MALDI). The analyte substance may be handled using a pipette. Droplets of the liquid analyte sample may be dropped onto the matrix 152 using a pipette 180. The volume of the droplet may be predetermined and / or selected for the intended measurement. The matrix 152 may be mass-produced. It is also possible that the pipette 180 is provided over a conveyor belt transporting each matrix 152 below the pipette 180. In this way, an automatised method for preparing the analyte so projectile 153 may be provided.

[0166] Figure 5 shows photos of a wire 204 being installed in the Q-array 202 of the mass spectrometer 100 of Figure 1. This simple experimental modification creates a baffle 164 in a form of a wire 204 which is located in the path of a supersonic gas jet plume 208 created by an intake 210 of the desolvation line 104. The experimental conditions generated in this way are similar to the proposed ion sources 142 of Figures 2 or 3.

[0167] The mass spectrometer 100 as depicted on Figure 1 is blind to any neutral molecules and / or atoms and / or any neutral droplets generated by the electrospray ionisation source 102. This is confirmed by the graphs of Figure 6 which shows two groups of mass spectra, a first spectrum obtained using with the instrument 100 of Figure 1 and same instrument modified (modified instrument 280 in the following) with the wire 204 serving as the baffle 164 for collision.

[0168] The instrument 100 of Figure 1 was tested with a Myoglobin sample diluted in the mixture of methanol and water with drop of formic acid. Ions were generated by the electrospray ionisation source 102. The resulting mass spectrum 260 shows typical Myoglobin peaks. 8628380

[0169] 20

[0170] The projectile 253 containing Myoglobin was created with the use of 3-Nitrobenzonitrile powder mixed with drop of methanol, then Myoglobin from the electrospray ionisation source 102 was added. The solid mixture was exposed directly to the intake of the desolvation line 104. The mass spectrum showed no ions in the spectrum 270, with random exceptions of noise 252.

[0171] The same experiments were repeated for the modified instrument 280 using the approach as depicted on Figure 2. The ions generated using the electrospray ionisation source 102 were blocked by the wire 204 and empty mass spectrum was measured 290. That proved that the wire 204 was in the position in which it acts as the collision structure 146.

[0172] The analyte-soaked projectile 153 containing Myoglobin was then tested. Myoglobin type peaks can be visible on the mass spectrum 300. It is important to emphasize that the peak heights and distribution for the spectrum 260 and for the spectrum 300 are different, proving different ionisation mechanism.

[0173] To confirm the mechanism of triboionisation, another experiment was performed. The tribocharging mechanism responsible for triboionisation is often associated with triboluminescence. To check presence of the triboluminescence in mass spectrometry, the front of the mass spectrometer 100 depicted on Figure 2 was re-created in a separate system 320 (see Figure 7). The Q-array 106 region was created with a vacuum chamber 322 equipped with two transparent walls. The desolvation line 326 was installed to provide same gas intake as for the original mass spectrometer 100. A rouging pump 346 was used to pump the chamber 322, with pressure regulator 330 to have the same value as in the Q-array 106 region. The baffle 164 was made from the bend metal piece 328. To assure that the conditions after sealing are shielded from light, a camera 332 was used. The sealing was provided with the aluminium foil 344 and experiments were conducted in the dark room. The photons were detected by the photomultiplier 324 from the modified ratemeter 342. The modification of a ratemeter 342 was conducted by removal of metalized mylar foil from the cover and scintillating crystals, exposing photomultiplier 324 to external photons. During the experiments in the dark a deriving unit of the modified ratemeter 342 provided sound output for detected ions.

[0174] As the first test sample, a cane of sugar powder was used. The cane sugar crystals when smashed in the darkness with a hammer can produce visible flashes of light. When cane sugar was inserted into the desolvation line 326, strong counts from the ratemeter 342 could be heard as indication of generated ions.

[0175] The same experiment was repeated with the 3-Nitrobenzonitrile powder, which was also used to obtain the mass spectrum 300. The strong counts from the ratemeter 342 were heard as indication of detected photons.

[0176] These experiments proved that triboluminescence was present during experiments with impact ionisation where mass spectrum 300 was generated. The triboluminescence is result of tribocharging which supports triboionization mechanism of the mass spectrum 300. A similar experiment demonstrating the effects of triboionization and triboluminescence is described in J. Am. Soc. Spectrom. (2019) 30:1503- 1511 , Natsuhiko Sugimura et al. 8628380

[0177] 21

[0178] A method for generating ions of an analyte substance for an ion detecting device such as the mass spectrometer is explained in connection with Figure 8.

[0179] In step S1 , the analyte substance is accelerated. This may be done using the analyte-soaked projectile 153 discussed above. In one example, the projectile storage means 156 is controlled to place the analyte- soaked projectile 153 at the start location 158a. Once the actuator of the projectile storage means 156 sends a confirmation signal to a controller that the cavity of the projectile array 156a including the analyte- soaked projectile 153 that is next to be accelerated is at the start location, the controller may control the motor 161 to rotate the disc 162 such that the though-hole of the disc 162 is aligned with the pipe 158 (i.e. the closure device 160 is in the open position). Due to the negative pressure inside the chamber 168, the analyte-soaked projectile 153 is accelerated towards the collision structure 146. After a predetermined period of time or after the analyte-soaked projectile 153 has hit the collision structure 146, the controller controls the motor 161 to rotate the disc such that any through-hole of the disc 162 is offset to the pipe 158 (i.e. the closure device 160 is in the closed position). For the next analyte-soaked projectile 153, the above process can be repeated.

[0180] Alternatively, the liquid feeding means 170 places a small amount (e.g. a droplet) of the liquid analyte substance at the start location 158a. Once this process is completed, the motor 161 may be controlled to rotate the disc 162 such that the though-hole of the disc 162 is aligned with the pipe 158 (i.e. the closure device 160 is in the open position). Due to the negative pressure inside the chamber 168, the analyte substance is accelerated towards the collision structure 146. Further, the analyte substance freezes due to the negative pressure inside the chamber 168 such that frozen analyte substance collides with the collision structure 146 which is considered to increase the triboelectric charge transfer. After a predetermined period of time or after the analyte substance has hit the collision structure 146, the motor 161 may be controlled to rotate the disc 162 such that any through-hole of the disc 162 is offset to the pipe 158 (i.e. the closure device 160 is in the closed position). For the next analyte-soaked projectile 153, the above process can be repeated.

[0181] In step S2, the analyte-soaked projectile 153 or the frozen analyte substance collides with the collision structure 146 and is firstly deformed and then scattered into many particles due to the impact onto the collision structure 146. In case of the analyte-soaked projectile 153, the matrix 152 is tribo-chargeable resulting to a triboelectric charge transfer which ionises the analyte substance. In case of the frozen analyte substance, the analyte substance itself is subjected to triboelectric charge transfer which ionises the analyte substance.

[0182] In step S3, the ionised analyte substance is guided towards the ion detecting device, e.g. the mass spectrometer 100. This is done by guiding the ionised analyte substance towards the outlet 168a in the chamber 168 which is subjected to the vacuum or low pressure in the ion detecting device. In other words, the ionised analyte substance is sucked into the mass spectrometer 100. Optionally, it is possible to supply a gas into the chamber 168 for providing a gas flow from the inlet of the chamber 168 towards the outlet 168a which may improve the transport of the ionised analyte substance towards the outlet 168a. 8628380

[0183] 22

[0184] Further, it is possible in step S3 that the electrodes 166 generate an electric field that decelerate the scattered ionised analyte substance and / or accelerate the ionised analyte substance towards the outlet.

[0185] In Step S4, the ionised analyte substance is measured and / or analysed using the ion detecting device, e.g. the mass spectrometer 100 as commonly known.

[0186] The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

[0187] While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0188] For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0189] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0190] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0191] It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example + / - 10%.

[0192] References

[0193] A number of publications are cited above in order to more fully describe and disclose the invention and the state of the art to which the invention pertains. Full citations for these references are provided below. The entirety of each of these references is incorporated herein.

Claims

1. 862838023Claims:1 . An ion source for an ion detecting device, wherein the ion source is configured to generate ions of a liquid or solid analyte substance, wherein the ion source comprises: a collision structure; an accelerating device configured to accelerate the liquid or solid analyte substance towards the collision structure for collision therewith to scatter the analyte substance and thereby induce ionisation of the analyte substance by triboelectric charge transfer; and collection means for guiding the ionised analyte substance to the ion detecting device.

2. The ion source of claim 1 , wherein the accelerating device is configured to accelerate a projectile containing the analyte substance.

3. The ion source of claim 1 or 2, wherein the accelerating device includes a gas pressure means configured to generate a gas pressure difference between a start location and the collision structure, wherein the start location is a location at which the projectile and / or the analyte substance are to be located prior to the projectile being accelerated towards the collision structure.

4. The ion source of claim 3, wherein the gas pressure means includes a pipe, a gas-tight chamber, and a gas pump, wherein the pipe contains the start location, wherein the projectile is configured to be accelerated from the start point along a longitudinal axis of the pipe, wherein the longitudinal axis is directed towards the collision surface, wherein the pipe extends through a wall of the chamber, and wherein the gas pump is configured to generate a negative pressure in the chamber for sucking the projectile from the start location into the chamber.

5. The ion source of claim 3 or 4, further comprising a liquid feeding means configured to supply the liquid analyte substance to the start location.

6. The ion source of any one of the claims claim 2 to 4, wherein the accelerating device further includes a projectile storage means for storing a plurality of projectiles.

7. The ion source of claim 6, wherein the projectile storage means is configured to place each projectile at the start location one after the other.

8. The ion source of claim 6 or 7, wherein the projectile storage means includes a projectile array and an actuator configured to move the projectile array, wherein the projectile array includes a plurality of cavities, each cavity being configured to hold a single projectile, and862838024 wherein the actuator is configured to position the projectile array such that the cavity is located at the start position.

9. The ion source of any one of the claims claim 6 to 8, wherein the projectile storage means is removably attachable to the ion source.

10. The ion source of any one of the claims claim 5 to 9, wherein the accelerating device further comprises a closure device for selectively closing the pipe in at least one closed position, optionally in gas-tight matter, and opening the pipe to the chamber in at least one open position.11 . The ion source of claim 10, wherein the closure device includes a disk and a motor for rotating the disk between the at least one open position and the at least one closed position, wherein in the disk includes at least one through-hole, wherein the motor is configured to position the disk such that the at least one through-hole aligns with the pipe in the open position and the at least one through-hole is offset from the pipe in the closed position.

12. The ion source of any preceding claim, wherein the collision structure is provided by a solid block or a mesh.

13. The ion source of any preceding claim, further comprising a vibration means configured to vibrate the collision structure for removing residues from the collision structure.

14. The ion source of any preceding claim, wherein the collection means includes a collection chamber having an outlet configured to be connected to the ion detecting device, wherein the outlet is configured to be subjected to a negative pressure.

15. The ion source of claim 14, wherein the collection means includes at least one electrode for generating an electrical field interacting with the ionised analyte substance, wherein the at least one electrode is arranged and / or shaped to actuate the ionised analyte substance to the outlet.

16. A projectile for the ion source of any preceding claim, comprising a matrix configured to contain the liquid or solid analyte substance and configured to be accelerated by the accelerating device.

17. The projectile of claim 16, wherein the matrix is configured to absorb the liquid analyte substance.

18. The projectile of claim 16 or 17, wherein the matrix is made from a tribo-chargeable material for inducing ionisation of the analyte substance by triboelectric charge transfer between the tribo-chargeable material of the matrix and / or between the tribo-chargeable material and the analyte substance.86283802519. An ion source assembly including the ion source according to any one of the claims 1 to 15 and the projectile of any one of the claims 16 to 18.

20. An ion detecting device including the ion source assembly of claim 19.21 . A method for generating ions of a liquid or solid analyte substance for an ion detecting device, comprising the steps of accelerating the liquid or solid analyte substance; colliding the analyte substance with a collision substrate to scatter the analyte substance and thereby induce ionisation of the analyte substance by triboelectric charge transfer; and guiding the ionised analyte substance to the ion detecting device.

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