Interface and method for the preparation of biological material for transfer into a mass spectrometer

Abstract

The present invention relates to an interface (1) for preparing material, in particular biological material, for transfer into a mass spectrometer, the material being in the form of an aerosol, the interface comprising an ionization device (2) for generating an ionized mist, and an ionization chamber (3) having a material inlet, a mist inlet for bringing the material in contact with the ionized mist in a mixing zone, the ionization device being configured to generate the ionized mist upstream of the mixing zone. The invention also relates to a method for preparing material using an interface of said kind.

Description

Description Title: Interface and process for preparing biological material for its transfer into a mass spectrometer Technical field

[0001] The present disclosure relates to the field of mass spectrometer interfaces. More particularly to an interface and a method for preparing biological material for transfer into a mass spectrometer. Prior art

[0002] In all fields of biology and medicine, the identification of specimens, whether in a physiological or physiopathological state, is of crucial importance, particularly in the context of diagnosis, prognosis and treatment of diseases.

[0003] For example, cancer is diagnosed based on information gathered by imaging methods. These imaging methods (e.g., CT scans, MRIs) can provide high-resolution images, but these high-resolution methods do not provide sufficient information, particularly for identifying malignant growths. Conversely, other methods (e.g., nuclear imaging techniques) with lower-resolution images can provide relevant information on the spread of the disease. Generally, one or more of these imaging methods in combination must be used to identify and localize a cancer.

[0004] An accurate diagnosis of pathological or abnormal tissues is usually obtained by histology, the branch of biology concerned with the study of biological tissues, or by cytology, the branch of biology concerned with the study of cells.

[0005] These imaging and analysis methods allow for the effective diagnosis of pathological or abnormal tissues. However, these methods do not provide information on the location of malignant tissues during surgery.

[0006] One way to circumvent this problem is to perform a histopathological examination of tissue removed during surgery. This involves making an extemporaneous diagnosis and observing whether the boundaries of the malignant tissue are well defined in the removed tissue. This procedure is very widespread despite various disadvantages such as time requirements (usually 20 to 50 minutes depending on the case and the institution) while keeping the patient in the operating room. Other methods are used, such as sonography or X-ray fluoroscopy. Despite useful results, these methods do not are not sensitive enough to identify the presence of a limited number of malignant cells.

[0007] Malignant tissues, like tumors, differ from healthy tissues in several ways. Tumors, in fact, have a very different molecular composition, ranging from the distribution of small metabolic constituents and lipids to the expression of different proteins. These molecular characteristics can be used for tumor visualization, using different imaging techniques, including molecular imaging of tissues by infrared spectrophotometry or mass spectrometry. Among these methods, mass spectrometry can serve as the basis for an in situ, in vivo tissue identification tool, by analyzing the different molecular compositions of different tissues.

[0008] Ionization mass spectrometry methods were initially developed for the analysis of gaseous or volatile materials. One of the disadvantages of these ionization methods is that they do not allow the analysis of non-volatile compounds, which represent approximately more than 90% of the molecules relevant for the analysis of pathological tissues.

[0009] Since the 1940s, new ion production methods have been developed that allow the production of gas-phase ions directly from a solid sample. Most of these methods involve a desorption / ionization process. Desorption ionization methods employ an analytical beam to promote desorption and ionization. The analytical beam includes entities of different composition (atoms, molecules, atomic or molecular ions, photons, etc.) that are directed onto the sample surface and delivered with varying energy levels.

[0010] For example, the Secondary Ion Mass Spectrometry (SIMS) method involves bombarding the surface of the sample to be analyzed with a highly accelerated ion beam. The sample is then sputtered, and some of the sputtered material is ionized. However, this technique has the disadvantage of requiring high vacuum conditions. The samples are therefore introduced into the high vacuum chamber of the mass spectrometers, which implies strong restrictions on the composition and geometry of the samples, and also requires special systems for their introduction.

[0011] The question of the need for desorption ionization methods operating under atmospheric conditions has been raised. Operation at atmospheric pressure and more specifically under ambient conditions (Ambient Ionization Mass Spectrometry (AIMS)) offers in particular the advantages of a more precise analysis procedure. faster and more flexible, as well as the absence of sample pre-treatments such as extraction of compounds of interest. In addition, biological systems, including living organisms, can be studied in vivo and in situ. All this allows the application of these methods for in situ identification of tissues.

[0012] Examples of these ambient methods include Rapid Evaporative Ionization Mass Spectrometry (REIMS), which uses a heated collision surface to produce ions from an aerosol; Extractive Atmospheric Pressure Photo-Ionization (EAPPI), which uses an ultrasonic nebulization system to nebulize and vaporize samples that are then mixed with a gaseous dopant and interact with photons in the ambient environment to ionize analytes in the gas phase;Easy Ambient Sonic Spray Ionization (EASI) which uses a stream of nebulized solvent directed against a surface, the solvent interacting and carrying away analytes by evaporation during which the analyte is ionized and released into the gas phase; and Droplet Assisted Inlet Ionization (DAII) which brings aqueous droplets into contact with particles suspended in the air, upon entering the mass spectrometer, these droplets being heated, their rapid evaporation leads to the formation of molecular ions.;

[0013] More recently, the Desorption Electrospray Ionization (DESI) method has been developed. This method uses charged solvent droplets as the analytical beam. The DESI method meets all the expectations associated with ambient ionization methods, and thus has opened the door to mass spectrometric analysis of objects of varying molecular composition, size, and geometry.

[0014] The study of tissues by means of mass spectrometry has been pursued in two fundamentally different ways. The first approach focused on the characterization, long, but as exhaustive as possible, of the molecules present in the tissues by strategies based on the extraction of particular families of compounds (metabolites, lipids, proteins, etc.) and coupling mass spectrometry with separation methods (e.g. gas or liquid chromatography), while the second focused on a rapid analysis without extraction or separation, similar to rapid and direct molecular fingerprinting.

[0015] Methods belonging to the first group generally begin with the homogenization and lysis of a certain amount of tissue, followed by selective extraction of the group of compounds of interest. The compounds are separated by electrophoresis or chromatography, and then analyzed by mass spectrometry. Although these methods cannot be used for instant tissue identification, they provide valuable information on the marker molecules characteristic of a particular tissue type, variations in their relative abundance, and the signaling pathways in which these molecules are involved.

[0016] Rapid molecular fingerprinting of tissues by mass spectrometry is generally obtained by the methods described above and in particular the desorption / ionization methods (SIMS, MALDI) and AIMS.

[0017] The desorption and ionization of non-volatile samples in the condensed phase using lasers has been researched since the late 1960s.

[0018] Most laser desorption methods result in the formation of aggregates of molecules of various sizes, the vast majority of which are neutral; this is why these methods have often been combined with post-ionization techniques. Post-ionization has traditionally been performed by electron impact (El) or chemical ionization (Cl). More recently, an approach using post-ionization by electrospray ionization (ESI) of gaseous species obtained by laser ablation of samples (LAESI) has been introduced. However, these methods have the disadvantage of either not being able to completely break up the molecular aggregates, or of not having an ionization yield that allows for better sensitivity and signal depth that can be analyzed by the mass spectrometer.

[0019] There is therefore still a need to provide an appropriate interface to prepare the sample for analysis after its collection and before transfer to a mass spectrometer (in particular to the mass analyzer) allowing the breaking of molecular aggregates and improving the ionization of the sample molecules (i.e. post-ionization). Summary

[0020] This disclosure is intended to provide a solution to the situation.

[0021] According to a first aspect, there is proposed an interface for preparing material, in particular biological material, for its transfer into a mass spectrometer, the material being in the form of an aerosol (neutral or partially ionized), the interface comprising: - an ionization device for generating an ionized nebulizer, and - an ionization chamber comprising two entrances and configured to receive the material in aerosol form through one of its inlets and to be connected to the ionization device through the other of its inlets in order to bring the material in aerosol form into contact with the ionized nebulization in a mixing zone, the ionization chamber comprising an outlet for the ionized material; characterized in that: - the ionization device is configured to generate the ionized nebulizer upstream of the mixing zone.

[0022] The interface according to the first aspect of the invention makes it possible to break up the aggregates of molecules of material, in particular biological material, coming from the sample collection site in the form of an aerosol and to ionize or improve the ionization efficiency of this material. Thanks to the ionization chamber receiving the material and the nebulizate generated by the ionization device, the material solvates in the ionized droplets of the nebulizate and then desolvates. This solvation disaggregates the material allowing the material molecules to be separated and ionized by charge transfer. This improvement in the ionization efficiency, that is to say the increase in the conversion rate of neutral material molecules into charged molecules, makes it possible to increase the sensitivity of the analysis carried out by the mass spectrometer.

[0023] According to a second aspect, there is provided a method of preparing material for its transfer into a mass spectrometer comprising: - injection of the material in aerosol form into an ionization chamber, - the generation of an ionized nebulizer, - mixing the ionized nebulizer in a mixing zone of the ionization chamber with the material leading to the solvation and ionization of the material, - the aspiration of the ionized material into a mass spectrometer connected to the outlet of the ionization chamber, characterized in that: - the ionization device is configured to generate the ionized nebulizer upstream of the mixing zone of the ionization chamber.

[0024] The features set out in the following paragraphs may, optionally, be implemented, independently of each other or in combination with each other: Brief description of the drawings

[0025] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: Fig. 1

[0026] [Fig. 1] shows a cross-sectional diagram of the interface according to the first aspect of the invention Fig. 2

[0027] [Fig. 2] shows a schematic representation of the method according to the second aspect of the invention Description of the embodiments

[0028] Interface 1

[0029] Reference is now made to Figure 1.

[0030] The present invention proposes, according to a first aspect, an interface 1 for preparing material, in particular biological material, for its transfer into a mass spectrometer, the material being in aerosol form, the interface 1 comprising: - an ionization device 2 for generating an ionized nebulizer, and - an ionization chamber 3 comprising two inlets 31, 32 and is configured to receive the material in aerosol form via one of its inlets 31, 32 and to be connected to the ionization device 2 via the other of its inlets 31, 32 in order to bring the material in aerosol form into contact with the ionized nebulization in a mixing zone 30, the ionization chamber 3 comprising an outlet 33 for the material downstream of the mixing zone; and characterized in that: - the ionization device 2 is configured to generate the ionized nebulization upstream of the mixing zone 30.

[0031] This interface 1 can advantageously replace the usual source of the mass spectrometer and be configured to be inserted directly on the inlet of the instrument (area from which the mass spectrometer is under vacuum). The ionized nebulization notably comprises charged solvent droplets, the size of which follows a distribution dependent on the size of the outlet orifice of the system used to generate the ionized nebulization but usually being between 100 nm and 500 nm.

[0032] The material that is ionized in interface 1 is in the form of particles, in particular particles of biological tissues, desorbed or ablated. Desorption or ablation can in particular be carried out by a laser. The biological tissues from which the biological material is taken can be any tissue of biological origin with or without transformation such as plant tissues (including cellulose-based materials), animal tissues including human (for example: nervous tissues, muscular tissues, epithelial tissues, cancerous tissues, or connective tissues), or microorganisms (e.g. bacteria, viruses, yeasts). Biological material is thus mainly made up of aggregates of biomolecules (proteins, metabolites, lipids, etc.). They generally contain very few charges. Non-biological materials include drugs, xenobiotics, inorganic materials, metallic, organometallic or plastic compounds. Subsequently, the description will refer to biological materials. However, the description also covers the case of non-biological materials.

[0033] During ablation or desorption, a certain volume of material is ejected in the gas phase. Thus, when the samples to be analyzed are taken, they are in the form of an aerosol comprising solid particles, in particular aggregates of molecules of biological material, in a gaseous medium. This gaseous medium can in particular be a mixture comprising air, nitrogen, carbon dioxide, helium or other rare gas and water vapor.

[0034] During operation, the delivery of biological material can be achieved by the vacuum of the mass spectrometer directly or via a dedicated transfer system (a delivery tube). Since the ablation zone is at atmospheric pressure, the vacuum inside the mass spectrometer causes the aspiration of biological material from the ablation zone.

[0035] The interface 1 according to the first aspect of the invention comprises an ionization chamber 3. The ionization chamber 3 can be made from a block of material, for example metal (e.g. stainless steel, titanium, brass, aluminum, or their alloys) or plastic (polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), fluorinated ethylene-propylene (FEP), polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate glycol (PETG), or their mixtures). The inlets 31, 32 and outlet 33 of the ionization chamber 3 can be made on a face, in particular a lateral face, of the block of material. For practical reasons, this block of material can have a right cylindrical shape with a circular base, the surface generated by the generator of the cylinder forming the lateral face of the block. However, the block of material can have various shapes, for example: parallelepiped, prismatic, spherical, etc.

[0036] The ionization chamber 3 may have a shape such that, in operation, the flow from the biological material collection device and the flow from the ionization device 2 are orthogonal to each other.

[0037] The orthogonality of the flows of biological material and ionized nebulization allows in particular a better solvation of the biological material by the ionized nebulization. Indeed, The fact that the flows are orthogonal allows a good probability of impact and mixing of the aggregates of biological material with the charged droplets of the ionized nebulisate, thus increasing the separation of the aggregates of biological material. A greater proportion of solvated biological material molecules in the nebulisate droplets makes it possible to increase the proportion of isolated and ionized biological material molecules.

[0038] Thus, the ionization chamber 3 can have a T shape.

[0039] The T-shape is characterized by two main axes. The ionization chamber 3 may thus comprise a longitudinal through channel 34 with an inlet and an outlet corresponding respectively to one of the inlets 31 of the ionization chamber 30 and to the outlet 33 thereof and a second channel 35 with an inlet corresponding to the other inlet 32 ​​of the ionization chamber 3 and connected to the longitudinal through channel 34. The mixing zone 30 is located at the intersection of the first channel 34 and the second channel 35. The longitudinal through channel 34 and the second channel 35 may be orthogonal to each other.

[0040] Alternatively, the ionization chamber 3 may have a shape such that, in operation, the flow coming from the device for collecting the biological material and the flow coming from the ionization device 2 are transverse. Thus, the second channel 35 may be transverse to the longitudinal through channel 34 and in particular form an angle of between 20° and 120°, preferably between 30° and 110°, more preferably 80° and 100°, for example 90°, with the latter.

[0041] The interface 1 according to the first aspect comprises an ionization device 2 configured to generate the ionized nebulizate. For example, the ionization device 2 may be a nebulizer. A nebulizer is understood to mean any means for suspending a liquid in a gas. The nebulizer may be chosen from a pneumatic nebulizer, a membrane nebulizer, a pressure nebulizer, a saturated vapor nebulizer, and an ultrasonic nebulizer. A pneumatic nebulizer is a nebulizer using a compressed gas stream to tear droplets from a liquid and form a nebulizate. A membrane nebulizer is a nebulizer using a membrane perforated with small orifices and vibrating, the nebulizate being created by forcing the liquid to pass through the membrane. A pressure nebulizer is a nebulizer in which a pressurized liquid is forced through a very small orifice to generate the nebulizate.A saturated vapor nebulizer is a nebulizer in which a gas is passed through a heated or room temperature liquid, the gas being charged with vapor and droplets of this liquid in the form of a nebulisate which is then carried to the outlet. An ultrasonic nebulizer is a nebulizer. applying ultrasound to a liquid to make it vibrate at high frequency, thus generating droplets of this liquid and forming the nebulisate.

[0042] The ionization device 2 may also be a nano-electron-sprayer or a micro-electron-sprayer. Preferably, the ionization device 2 is a nano-electron-sprayer.

[0043] An electrospray is a device for transforming liquids into a cloud of extremely fine charged droplets. It breaks down solutions and / or suspensions into an aerosol comprising charged droplets of the solution and / or suspension. This aerosol is also called an ionized nebulizer, a term that will be used later. An electrospray is considered a nano-electrospray when the solvent flow rate through this needle is in the nL / min range, for example, 10 to 500 nL / min. The flow rate can be in a narrower range, such as 100 to 500 nL / min or 250 to 500 nL / min. It is considered a micro-electrospray when the solvent flow rate through the needle is in the pL / min range, for example, 10 to 500 pL / min. The flow rate can be in a narrower range, such as 100 to 500 pL / min or 250 to 500 pL / min.

[0044] The ionization device 2 may further comprise an alternating or direct current source 22 (not shown in FIG. 1) for its power supply in order to produce the ionized nebulization, in particular an absolute voltage of between 2 and 10 kV.

[0045] Subsequently, an example of an ionization device in the form of a nano-electronebulizer will be described in more detail.

[0046] The nano-electronebulizer 21 may comprise an emitter 211 from which the ionized nebulizer is generated. The nano-electronebulizer 21 may further comprise a solvent delivery tube 212.

[0047] The emitter 211 typically has the shape of a hollow needle. The solvent delivery tube 212 is fluidically connected to the interior of the hollow needle forming the emitter 211. The tip of the hollow needle forms the tip 213 of the nano-electronebulizer 21 by which the ionized nebulization is generated. This tip 213 can be arranged in the ionization chamber 3, upstream of the mixing zone 30. The smaller the diameter of the emitter 211, the smaller the size of the droplets of the ionized nebulization. A nano-electronebulizer differs from electronebulizers by its ionized nebulization spray flow rate, which is of the order of nL / min. It generally has a diameter at its end of between 5 and 50 μm. The size of the emitter 211 is configured so that the flow rate of the ionized nebulizer generated at the output of the nano-electronebulizer 21 is between 10 nL / min and 500 pL / min. This low flow rate of ionized nebulizer allows in particular to reduce the quantity of solvent required to ionize biological material in aerosol form.

[0048] Spraying the ionized nebulizer upstream of the mixing zone 30 makes it possible in particular to avoid pollution of the emitter 211 of the nano-electronebulizer 21. Indeed, the particles of biological material can be absorbed on the emitter 211 and deteriorate the spraying of the ionized nebulizer, resulting in an alteration of the effectiveness of the ionization. This arrangement thus makes it possible to improve the ionization of the biological material.

[0049] The ionization device 2 may further comprise an alternating or direct current source 22 (not shown in FIG. 1) to power the nano-electronebulizer 21 in order to produce the ionized nebulization, in particular an absolute voltage of between 2 and 10 kV.

[0050] The ionized nebulizer generated by the nano-electronebulizer 21 is sent into the mixing zone 30 of the ionization chamber 3. It allows the aggregates of biological material to be broken up in order to isolate the different molecules. These molecules of biological material solvate in the charged droplets of the nebulizer. By solvating in the charged droplets, the molecules of biological material ionize. After desolvation, molecules of biological material are obtained that are isolated in the gas phase and are wholly or partly charged.

[0051] Using a nano-electronebulizer 21 improves the mechanism of disaggregation by solvation of the biological material in the ionized nebulizer and therefore increases the quantity of ionized biological material that will be sent to the mass spectrometer.

[0052] The solvent conveyed by the solvent conveying tube 212 is chosen such that the separation of the aggregates of biological material as well as the solvation of the molecules of biological material in the solvent droplets is efficient. In addition It is chosen so as to have a high charge density in order to ionize the molecules of biological material. The solvent can be neutral with respect to the molecules of biological material. Its main function being the solvation and ionization of the molecules of biological material, it is necessary that the solvent does not alter their structure in order not to alter the subsequent analysis carried out by the mass spectrometer. Nevertheless, there are cases where the alteration of the molecules is desired. Thus, the solvent can be chosen so as to alter the molecules of the biological material and promote the observation of certain species. The solvent can consist of one or more compounds which can be for example chosen from: one or more organic solvents; one or more volatile compounds; one or more polar molecules; one or more non-polar molecules polar; water; and mixtures thereof. Examples of organic solvents include alcohols (e.g., methanol, ethanol, isopropanol, propanol, butanol, pentanol), acetone, acetonitrile, tetrahydrofuran, ethyl acetate, ethylene glycol, dimethyl sulfoxide, dimethylformamide, methyl tert-butyl ether, aldehydes, ketones; hexane, chloroform. In some embodiments, this solvent may be made acidic or basic; include a supercharging agent, a mass measurement compound (“lockmass”) or a calibration compound.

[0053] The ionization chamber 3 can be connected to a delivery tube 5 for the biological material in aerosol form and connected to the inlet of the ionization chamber. This delivery tube 5 can be included in the present interface 1. Alternatively, the delivery tube 5 is part of the laser sample collection equipment.

[0054] The delivery tube 5 may have a cylindrical shape with an internal diameter of between 0.1 and 12 mm, preferably between 1 and 8 mm, or even between 1 and 5 mm. Preferably, the delivery tube 5 is long and flexible enough to allow the operator to aspirate the ablated biological material regardless of the operating area and its difficulty of access and so that the interface 1 and the mass spectrometer are not too close to the sampling area. Since the delivery tube 5 may possibly be in contact with an open surgical wound, it is made in this case of a material which can be made sterile and used in the operating room. Preferably, the delivery tube 5 is made of a polymer material such as plastic or thermoplastic chosen, for example, from polycarbonate (PC), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS) or polytetrafluoroethylene (PTFE).

[0055] Alternatively, ionization chamber 3 can receive biological material directly.

[0056] The interface 1 according to the first aspect may comprise a transfer element to a mass spectrometer. For example, the transfer element may be a transfer tube 4 connected to the outlet 33 of the ionization chamber 3 and, in operation, to the transfer capillary of a mass spectrometer or inserted inside the latter in place of the transfer capillary.

[0057] The transfer tube 4 allows the ionized biological material to be transferred to the mass spectrometer. The transfer tube 4 is collinear with the longitudinal through channel 34 of the ionization chamber 3.

[0058] The transfer tube 4 may include a connector to the inlet of a mass spectrometer.

[0059] The transfer tube 4 may have a cylindrical shape whose internal diameter fits the external diameter of the transfer capillary of the mass spectrometer. If this transfer tube 4 is the element that brings the material inside the mass spectrometer then its internal diameter is between 200 pm and 3 mm, preferably 400 pm and 1 mm, more particularly 500 pm. It may be made of a material chosen from metal (stainless steel, titanium, brass), glass (for example, borosilicate glass or fused silica) or a high temperature resistant plastic such as polyethylene ketone (PEEK) or polytetrafluoroethylene (PTFE). The transfer tube 4 may have a variable length, for example, its length may be between 5 mm and 10 cm, more particularly 5 mm and 5 cm, more particularly 3 cm.

[0060] The ionization chamber 3 may alternatively comprise a connector for receiving the transfer capillary of the mass spectrometer.

[0061] After solvation, the ionized biological material molecules can be transferred to the mass spectrometer for analysis. Improving the ionization of biological material by the interface improves the analysis signal of the mass spectrometer, thereby improving the system's performance and making it easier to identify the molecules being analyzed. Thus, the operator analyzing the signal is better able to identify the composition of biological tissues and the presence or absence of pathological or abnormal elements.

[0062] Process

[0063] Reference is now made to Figure 2.

[0064] The invention proposes, according to a second aspect, a method for preparing material, in particular biological material, for its transfer into a mass spectrometer comprising: - the routing S1 of the material in aerosol form into the mixing zone of an ionization chamber, - the injection S2 of an ionized nebulization generated by an ionization device comprising solvent droplets charged in the mixing zone of the ionization chamber, - solvation then ionization S3 of the material in aerosol form by the ionized nebulizer, - the aspiration S4 of the at least partially ionized material into a mass spectrometer connected to the outlet of the ionization chamber, characterized in that: - the ionization device is configured to generate the ionized nebulizer upstream of the mixing zone of the ionization chamber.

[0065] In the following, the description will refer to biological materials. However, the description also covers the case of non-biological materials.

[0066] Step S1:

[0067] Step S1 involves delivering the biological material in aerosol form to an ionization chamber.

[0068] All or part of the biological material is in the form of aggregates of molecules as explained above.

[0069] Since the aerosolized biological material is desorbed or ablated or collected in an area at atmospheric pressure, the pressure difference generated by the vacuum inside the mass spectrometer can be used to draw the aerosolized biological material into the ionization chamber.

[0070] Step S2:

[0071] Step S2 comprises injecting a generated ionized nebulisate comprising charged solvent droplets by an ionization device into the mixing zone of the ionization chamber.

[0072] Step S2 comprises, in particular, the generation of the ionized nebulizer upstream of the mixing zone of the ionization chamber, preferably so that the spray direction of the ionized nebulizer is directed towards the mixing zone of the ionization chamber. Step S2 then comprises the injection of the ionized nebulizer into the mixing zone of the ionization chamber.

[0073] The ionized nebulizer can be generated at a flow rate between 10 nL / min and 500 pL / min.

[0074] In some cases, this flow rate may be in the order of nL / min, for example, 10 to 500 nL / min. The flow rate may be in a narrower range, such as 100 to 500 nL / min or 250 to 500 nL / min.

[0075] Alternatively, the flow rate may be in the order of pL / min, for example, 10 to 500 pL / min. The flow rate may be in a narrower range, such as 100 to 500 pL / min or 250 to 500 pL / min.

[0076] The fact that the flow rate is in the order of nL / min to pL / min allows a balanced compromise between the quantity of solvent used and the improvement of the solvation / desolvation process of the biological material in the charged solvent droplets.

[0077] Step S3:

[0078] Step S3 involves the ionization of the biological material in aerosol form by the ionized nebulizer in the ionization chamber. This ionization can be complete upon exiting the ionization chamber or continue outside the ionization chamber.

[0079] The flow of biological material in aerosol form and the flow of ionized nebulizate meet in the mixing zone of the ionization chamber. The mixing of the two flows leads to the solvation of the biological material in the droplets of the nebulizate solvent and allows, as explained previously, to break up the aggregates of biological material in order to isolate the biological material molecules. The isolated molecules are then solvated in the charged solvent droplets. The biological material molecules ionize in the charged solvent droplets and then desolvate to form ionized biological material molecules.

[0080] Step S3 may be carried out in such a way that the flow of biological material and the flow of ionized nebulizate are orthogonal to each other. Generally, the flow of nebulizate may be transverse to the flow of biological material, in particular forming an angle of between 20 and 120°, preferably between 30° and 110°, more preferably 80° and 100°, for example 90°, with the latter.

[0081] As explained previously, the fact that the two flows are orthogonal allows to improve the conversion of biological material aggregates into ionized biological material molecules by improving the separation of aggregates into isolated biological material molecules as well as their solvation in the charged solvent droplets.

[0082] Step S4:

[0083] Step S4 involves aspiration of the ionized biological material into a mass spectrometer.

[0084] The method according to the second aspect of the invention makes it possible to improve the ionization of the molecules of biological material and by extension the quantity of signal that can be analyzed by the mass spectrometer and therefore the quality of the analysis.

Claims

Claims

1. Interface (1) for preparing material, in particular biological material, for its transfer into a mass spectrometer, the material being in aerosol form, the interface comprising: - an ionization device (2) for generating an ionized nebulizer, and - an ionization chamber (3) comprising two inlets (31, 32) and configured to receive the material in aerosol form through one of its inlets and to be connected to the ionization device through the other of its inlets in order to bring the material in aerosol form into contact with the ionized nebulization in a mixing zone, the ionization chamber comprising an outlet (33) for the ionized material downstream of the mixing zone; characterized in that: - the ionization device is configured to generate the ionized nebulizer upstream of the mixing zone.

2. Interface according to claim 1, further comprising a tube (5) for conveying biological material in aerosol form and connected to the inlet of the ionization chamber.

3. An interface according to any preceding claim, wherein the ionized nebulizer is sprayed at a flow rate of between 10 and 500 nL / min.

4. An interface according to any preceding claim, wherein the ionized nebulizer comprises charged solvent droplets having a size between 100 nm and 500 nm.

5. An interface according to any preceding claim, wherein, in operation, the flow from the biological material delivery tube and the flow from the ionization device are orthogonal or transverse to each other.

6. Method for preparing material, in particular biological material, for its transfer into a mass spectrometer comprising: - the routing (S1) of the material in aerosol form into a mixing zone of an ionization chamber, - the injection (S2) of an ionized nebulization generated by an ionization device comprising droplets of solvent charged in the mixing zone of the ionization chamber, - solvation then ionization (S3) of the material in aerosol form by the ionized nebulizer, - the aspiration (S4) of the at least partially ionized material into a mass spectrometer connected to the outlet of the ionization chamber, characterized in that: - the ionization device is configured to generate the ionized nebulizer upstream of the mixing zone of the ionization chamber.

7. The method of claim 6, wherein step (S1) is performed by means of a pressure difference generated by the vacuum inside the mass spectrometer.

8. A method according to any one of claims 6 to 7, wherein the ionized nebulisate is sprayed from the nebulizer at a flow rate of between 10 and 500 nL / min.

9. A method according to any one of claims 6 to 8, wherein step (S3) is carried out in such a way that the flow of biological material and the flow of ionized nebulization are orthogonal or transverse to each other.

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