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

Abstract

The invention relates to an interface for preparing biological material for transfer into a mass spectrometer. The interface comprises a tube delivering the biological material in the form of an aerosol, a venturi system with two inlets and one outlet, a heating cartridge, a corona discharge needle for ionizing the biological material in aerosol form, a nebulizer for generating a mist, and a transfer tube connected to the outlet of the venturi system. The interface is arranged such that the heating cartridge is placed around the transfer tube, the corona discharge needle is located at the outlet of the transfer tube, and the venturi system is connected to the tube delivering the biological material and to the nebulizer by means of the two inlets, leading to the solvation of the biological material in aerosol form by the mist in the venturi system.

Description

Description Title: Interface and method for preparing 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 (i.e., tumor) tissues 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 by 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] Starting in the 1940s, new ion production methods were developed that allowed 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 Fast Atom Bombardment (FAB) method uses high-energy inert gas atoms to bombard the sample to be analyzed, allowing it to be pulverized and ionized. The Secondary Ion Mass Spectrometry (SIMS) method consists of bombarding the surface of the sample to be analyzed with a highly accelerated ion beam. The sample is then pulverized, and part of the pulverized material is ionized. However, these techniques have 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 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 the advantages of a faster and more flexible analysis procedure and the absence of sample pretreatments such as extraction of compounds of interest. Furthermore, biological systems, including living organisms, can be studied in vivo and in situ. All this allows the application of these methods (AIMS) for in situ tissue identification.

[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 focused on rapid, extraction- and separation-free analysis, similar to rapid, 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 investigated since the late 1960s. 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 aggregates of molecules, or of not having an ionization yield allowing for better sensitivity and the depth of the signal that can be analyzed by the mass spectrometer.

[0018] 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 (particularly at the mass analyzer level) to break up molecular aggregates and improve the ionization of sample molecules (i.e. post-ionization). Summary

[0019] This disclosure is intended to provide a solution to the situation.

[0020] 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: - a venturi system with two inlets and one outlet, - a heater, - a corona discharge needle for ionizing the material in aerosol form, characterized in that the interface further comprises: - a nebulizer to generate a nebulizate, - a transfer tube connected to the outlet of the venturi system, and in that: - the heater is configured to heat the transfer tube, - the corona discharge needle is located at the outlet of the transfer tube, and - the venturi system is configured to receive the aerosolized material through one of its inlets and is connected to the nebulizer through the other of its inlets leading to the solvation of the aerosolized material by the nebulizate in the venturi system.

[0021] The interface according to the first aspect of the invention makes it possible to break up the aggregates of material molecules coming from the sample collection site in aerosol form and to ionize or improve the ionization efficiency of this material. In the venturi system, connected to the nebulizer and the delivery tube, the material solvates in the droplets of the nebulizate and desolvates when it passes through the transfer tube surrounded by the heating cartridge. This solvation-desolvation makes it possible to disaggregate the material molecules in order to improve the ionization carried out by the corona discharge. This is delivered by the corona discharge needle which is located downstream of the transfer tube. This improvement in ionization, 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.

[0022] According to a second aspect, a method is proposed for preparing material, in particular biological material, for its transfer into a mass spectrometer comprising: - conveying the material in aerosol form to a venturi system, characterized in that the method further comprises: - the injection of a nebulisate comprising solvent droplets into the venturi system, - solvation in the venturi system of the material in the form of aerosol in the solvent droplets of the nebulisate, - heating the solvated material in the solvent droplets of the nebulisate through a transfer tube connected to an outlet of the venturi system, and - ionization of the material by a corona discharge delivered at the outlet of the transfer tube. Brief description of the drawings

[0023] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: Fig. 1

[0024] [Fig. 1] shows a diagram of the interface according to the first aspect of the invention with the material delivery flow and the venturi system output flow being collinear. Fig. 2

[0025] [Fig. 2] shows a partial sectional diagram of the venturi system and nebulizer according to the first aspect of the invention. Fig. 3

[0026] [Fig. 3] shows a diagram of the interface according to the first aspect of the invention with the nebulisate flow and the venturi system outlet flow collinear. Fig. 4

[0027] [Fig. 4] 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 and Figure 2.

[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 comprising: - a venturi system 2 with two inlets 21, 22 and one outlet 23, - a heating 3, - a corona discharge needle 4 for ionizing the material in aerosol form, characterized in that the interface 1 further comprises: - a nebulizer 5 to generate a nebulizate, - a transfer tube 6 connected to the outlet of the venturi system 2, and in that: - heater 3 being configured to heat transfer tube 6, - the corona discharge needle 4 is located at the outlet of the transfer tube 6, and - the venturi system 2 is configured to receive the material in aerosol form through one of its inlets 21, 22 and is connected to the nebulizer 5 through the other of its inlets 21, 22 leading to the solvation of the material in aerosol form by the nebulizate in the venturi system 2.

[0031] The material that is ionized in interface 1 is in the form of particles, including aggregated, ablated, or desorbed biological tissue particles. Ablation or desorption can be performed using 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 tissues (e.g., nervous tissues, muscle tissues, epithelial tissues, or connective tissues), or microorganisms (e.g., bacteria, viruses, yeasts). The 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. The description hereinafter refers to biological materials. However, the description also covers non-biological materials.

[0032] 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 a gas which can be air, nitrogen, carbon dioxide, helium or other rare gas and water vapor.

[0033] The interface 1 according to the first aspect comprises a nebulizer 5 for generating a nebulizate.

[0034] The nebulizer 5 is a device for transforming liquids into a cloud of extremely fine particles. It allows solutions and / or suspensions to be broken down into an aerosol comprising droplets of the solution and / or suspension. This aerosol is also called a nebulizate, a term that will be used subsequently.

[0035] Nebulizer 5 is any means of suspending a liquid in a gas. Nebulizer 5 may be selected from a pneumatic nebulizer, a membrane nebulizer, a pressure nebulizer, a saturated vapor nebulizer, and an ultrasonic nebulizer. A pneumatic nebulizer is a nebulizer that uses a stream of compressed gas to tear droplets from a liquid and form a nebulizate. A membrane nebulizer is a nebulizer that uses a vibrating membrane perforated with small orifices, the nebulizate being created by forcing the liquid 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 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 nebulizate which is then carried to the outlet. An ultrasonic nebulizer is a nebulizer that applies ultrasound to a liquid to make it vibrate at high frequency, thus generating droplets of this liquid and forming the nebulizate.

[0036] The nebulizer 5 may also be a nano-electronebulizer or a micro-electronebulizer. Preferably, the ionization device 2 is a nano-electronebulizer.

[0037] The following description is made in relation to a pneumatic nebulizer, but it also applies to other types of nebulizer. The pneumatic nebulizer is the most commonly used type of nebulizer. It is also known as an atomizer. It generally includes a means of conveying a high-speed compressed gas stream that is sent around a needle from which the liquid to be nebulized emerges. The passage of the gas results in the formation of the nebulizate by fragmenting the liquid.

[0038] The pneumatic nebulizer 5 may comprise an emitter 51 from which the nebulizate is generated, a solvent delivery tube 52 and a gas delivery tube 53. The solvent delivery tube 52 and the gas delivery tube 53 are connected to a base 55 on one side thereof and from which the emitter 51 extends from the other side opposite the first side.

[0039] The emitter 51 may comprise a tube 511 terminated in a point and a hollow needle 512. The tube 511 and the hollow needle 512 are coaxial. The tip of the hollow needle 512 protrudes from the tip of the tube 511. The solvent delivery tube 52 is fluidly connected to the interior of the hollow needle 512 while the gas delivery tube 53 is fluidly connected to the space between the tube 511 and the hollow needle 512. The tip of the tube 511 and the tip of the hollow needle 512 form the tip of the nebulizer 5 through which the nebulizate is generated. The smaller the inner diameter of the hollow needle 512, the smaller the size of the nebulizate droplets. It generally has an inner diameter of between 50 and 200 μm. The emitter 51 is configured so that the flow rate of the nebulizate generated at the outlet of the nebulizer 50 is between 100 nL / min and 2 mL / min. In some cases, the flow rate may be from 100 nL / min to 500 nL / min.In other cases, the flow rate may be 100 pL / min to 2 mL / min.

[0040] The solvent delivery tube 52 is used to deliver the solvent to the nebulizer 5 and the gas delivery tube 53 is used to deliver the gas to the nebulizer 5. The gas is used to spray the solvent into fine droplets to form the nebulisate. The nebulisate is thus in the form of an aerosol of fine droplets of solvent included in the gas which is conveyed by the gas conveying tube 53.

[0041] The interface 1 may further comprise a nebulization connector 54 in which the nebulizer 5 is placed, the nebulization connector 54 comprises an outlet 541 connected to the venturi system 2.

[0042] The nebulization connector 54 makes it possible to partially receive the nebulizer 5 and to connect it fluidically with the venturi system 2. The nebulization connector 54 preferably has a shape optimized for the efficient transfer of the nebulizate towards the interior of the venturi system 2, for example the shape is frustoconical (in particular its internal surface) whose side with the smallest section is at the level of the inlet of the venturi system 2 and receives inside it the tube 511 and the hollow needle 512 of the nebulizer 5 and making it possible to concentrate the flow of nebulizate towards the interior of the venturi system 2. The nebulization connector 54 extends from the base of the base 55 of the nebulizer 5 and beyond its tip, thus forming a nebulization chamber 56 between the tip and its end.

[0043] The distance between the inlet 21, 22 of the venturi system 2 and the tip of the nebulizer 5 may be between 1 and 50 mm, preferably 2 and 10 mm, always preferably 3 and 5 mm.

[0044] The interface 1 according to the first aspect comprises a venturi system 2. The venturi system 2 comprises two inlets 21, 22 and an outlet 23. The two inlets 21, 22 are connected to the delivery tube 7 of the biological material and to the nebulizer 5. In the case where the interface 1 comprises the nebulization connector 54, it is the nebulization connector 54 which is connected to an inlet 21, 22 of the venturi system 2 and not the nebulizer 5.

[0045] The nebulisate generated by the nebulizer 5 is sent to the venturi system 2. The flow of the nebulisate primes the venturi system 2. A vacuum is created inside the venturi system 2 and allows the biological material to be sucked in the form of an aerosol inside the venturi system 2. In addition, the nebulisate also breaks up the aggregates of biological material in order to isolate the different molecules of biological material. These molecules of biological material solvate in the droplets of the nebulisate.

[0046] The solvent conveyed by the solvent conveying tube 52 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. The solvent may be neutral with respect to the molecules of biological material. Since its main function is the solvation of the molecules of biological material, it is necessary that the solvent does not alter them so as not to alter the subsequent analysis carried out by the mass spectrometer. However, 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 be chosen from: an organic solvent; a volatile compound; polar molecules; non-polar molecules; water; one or more alcohols (methanol, ethanol, isopropanol, propanol, butanol, pentanol); acetone; acetonitrile; tetrahydrofuran; ethyl acetate; ethylene glycol; dimethyl sulfoxide or dimethylformamide; methyl-tert-butyl-ether, an aldehyde; a ketone; hexane; chloroform. In some embodiments, this solvent may include a supercharging agent, a mass measuring (“lockmass”) compound or a calibration compound.

[0047] The compressed gas conveyed by the gas conveying tube 53 is chosen so that it has no impact on the biological material. Since solvation is carried out between the molecules of biological material and the solvent droplets, the compressed gas must be neutral with respect to the molecules of biological material so as not to alter them and therefore not to alter the analysis of the mass spectrometer.

[0048] However, in some cases it is desirable for the gas to be able to interact with the molecules of the biological material and / or the solvent, for example ammonia to promote proton transfer.

[0049] The compressed gas may be selected from nitrogen and compressed air, preferably the gas is nitrogen.

[0050] The venturi system 2 may comprise a routing connector making it possible in particular to receive a routing tube 7 for the biological material in aerosol form. This routing tube 7 may be in the present interface. Alternatively, the routing tube is part of the laser sample collection equipment.

[0051] The delivery tube 7 may have a cylindrical shape with a diameter of between 1 and 12 mm, preferably between 1 and 8 mm, or even between 1 and 5 mm. Preferably, the delivery tube 7 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 operating area. Since the delivery tube 7 may possibly be in contact with an open surgical wound, it is made in this case of a material that can be made sterile and used in the operating room. Preferably, the delivery tube 7 is made of a plastic or thermoplastic material chosen from polycarbonate (PC), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS) or polytetrafluoroethylene (PTFE) for example.

[0052] The venturi system 2 has in particular a shape such that, in operation, the flow coming from the biological material delivery tube 7 and the flow coming from the nebulizer 5 are transverse, or even orthogonal, to each other.

[0053] The orthogonality of the flows of biological material and nebulisate allows in particular a better solvation of the biological material by the nebulisate. Indeed, the fact that the flows are orthogonal allows a good probability of impact of the aggregates of biological material with the droplets of the nebulisate thus making it possible to increase 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 biological material molecules.

[0054] The venturi system 2 can have a T shape, alternatively it can have a Y shape.

[0055] The T-shape is characterized by two main axes. The venturi system 2 may thus comprise a longitudinal through channel 24 with an inlet and an outlet corresponding respectively to one of the inlets 21 of the venturi system 2 and to the outlet 23 thereof and a second channel 25 with an inlet corresponding to the other inlet 22 of the venturi system 2 and connected to the longitudinal through channel 24, the longitudinal through channel 24 and the second channel 25 being orthogonal to each other.

[0056] Alternatively, the venturi system 2 has a shape such that, in operation, the flow coming from the biological material delivery tube and the flow coming from the nebulizer 5 are transverse. Thus, the second channel can be transverse to the longitudinal through channel and in particular forms an angle of between 20 and 120° with the latter, preferably between 30° and 110°, more preferably 80° and 100°, for example 90°.

[0057] The destination of the inlets 21, 22 of the venturi system 2 is not fixed. It is thus possible to interchange the different flows between the two inlets 21, 22. The inlet 21 corresponds to one of the ends of the longitudinal through channel 24 and the inlet 22 to the end of the second channel 25.

[0058] The delivery tube 7 and the nebulizer 5 can be arranged in such a way that, in operation, the flow at the outlet of the venturi system 2 is colinear with the flow coming from the delivery tube 7 of the biological material.

[0059] In this configuration, the delivery tube 7 is connected to the inlet 21 and the nebulizer 5 to the inlet 22, in particular via the nebulization connector 54 arranged at this location. This configuration corresponds to the interface 1 shown in Figures 1 and 2. In this configuration, the flow from the delivery tube 7 is collinear with the longitudinal through channel 24 and the flow of nebulized material from the nebulizer 5 is collinear with the second channel 25 of the venturi system 2.

[0060] The delivery tube 7 and the nebulizer 5 may be arranged in such a way that, in operation, the flow at the outlet of the venturi system 2 is collinear with the flow coming from the nebulizer 5. In this configuration, the flow of biological material coming from the delivery tube 7 is collinear with the second channel 25 of the venturi system 2 and the flow coming from the nebulizer 5 is collinear with the longitudinal through channel 24.

[0061] In this configuration, the nebulizer 5 is connected to the inlet 21 via in particular the nebulization connector 54 arranged at this location, and the routing tube 7 to the inlet 22. This configuration corresponds to the interface 1 shown in figure 3.

[0062] The longitudinal through channel 24 may have a first circular section at the inlet 21, a second section at the outlet 23 of the channel and a third circular section in an intermediate zone 241 between the inlet 21 and the outlet 23. The ratio between the third circular section and the first circular section may be between 0.25 and 0.75, preferably 0.35 and 0.65, more particularly 0.5. The ratio between the third circular section and the second circular section may be between 0.25 and 0.75, preferably 0.35 and 0.65, more particularly 0.5. The first section and the second section may be identical or different. In the latter case, the second section may be smaller or larger than the first section.

[0063] The intermediate zone 241 thus has a smaller circular section than at the inlet 21 and at the outlet 23 of the longitudinal through channel 24 of the venturi system 2. It is this difference in section which is at the origin of the Venturi effect. This difference in section causes a depression at the level of the zone where the section is the smallest. The tube 7 for conveying the biological material having one end at atmospheric pressure, this depression causes the suction of the biological material from the ablation zone. The smaller the ratio between the third circular section and the first or second circular section, the greater the depression. Conversely, the flow velocity at the level of the intermediate zone 241 of the longitudinal through channel 24 is much greater than that at the inlet 21 and at the outlet 23 of the through channel 24. This increase in the flow velocity makes it possible to tend towards a more turbulent flow regime than at the inlet 21 or at outlet 23 of the venturi system 2, thus improving the separation of aggregates of biological material into isolated molecules of biological material and therefore the solvation of these molecules.

[0064] The second channel can open into the intermediate zone of the longitudinal through channel.

[0065] The second channel of the venturi system 2 may have a nebulizer inlet portion and an end portion for connection to the longitudinal through channel. The inlet portion has a longitudinal axis that is not collinear with that of the connection portion. In the above description concerning the angles formed by the longitudinal through channel and the second channel, the reference axis for the second channel is that of the inlet portion. Preferably, the longitudinal axis of the connection portion is configured so that the nebulization inlet flow F2 and the aerosol flow F3, at their intersection, form an acute angle, for example between 10 and 80°, preferably between 20 and 50°, always preferably between 25 and 40°, for example approximately 30°. This angle may advantageously correspond to the passage slope between the first section and the third section.

[0066] The venturi system 2 may further comprise a suction adjustment part 26 arranged in the longitudinal channel passing through at the outlet of the venturi system 2.

[0067] The suction adjustment part 26 may have a tube shape of circular section whose external diameter allows its insertion into the venturi system 2. It may have an annular protrusion 261 on its external surface forming a collar in order to block the insertion of the suction adjustment part 26 by contact of the annular protrusion 261 against the edge corresponding to the outlet 23 of the venturi system 2 thus ensuring the projection of the suction adjustment part 26 out of the venturi system 2. This suction adjustment part 26 may have a fourth circular section smaller than the second circular section in order to reduce the circular section at the outlet of the longitudinal through channel to adjust the suction of the biological material by varying the depression created by the venturi system 2.

[0068] The ratio between the fourth circular section and the second circular section may be between 0.5 and 1.5, preferably between 0.5 and 0.89, always preferably 0.6 and 0.8, more particularly 0.7.

[0069] The venturi system 20 may be made entirely or partly of a material chosen from 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 mixtures thereof).

[0070] The interface 1 according to the first aspect comprises a transfer tube 6 connected to the outlet 23 of the venturi system 2, a heater 3 configured to heat the transfer tube 6 and one or more corona discharge needles 4 (hereinafter the singular is used) to ionize the biological material in aerosol form exiting the outlet of the transfer tube 6.

[0071] The transfer tube 6 allows the transfer of the biological material solvated in the solvent droplets at the outlet 23 of the venturi system 2 to the corona discharge needle 4. The transfer tube 6 is collinear with the transverse longitudinal channel of the venturi system 2.

[0072] The transfer tube 6 may have a circular section with a diameter of between 2 and 8 mm, preferably 2 and 5 mm, more particularly 3 mm. It may be made of a material chosen from metal (stainless steel, titanium, brass, aluminum), glass or high temperature resistant plastic such as polyethylene ketone (PEEK) or polytetrafluoroethylene (PTFE).

[0073] The heater 3 may be a heating cartridge located around the transfer tube 6 to heat the biological material in the form of a solvated aerosol in order to desolvate the biological material. The heating cartridge 3 may be configured to deliver heat between 40 and 500°C, preferably between 100 and 300°C, more particularly 250°C.

[0074] Alternatively, the heating cartridge 3 can be replaced by other types of heating such as heating internal to the transfer tube 6 (for example a heating grid), microwave heating arranged around the transfer tube 3 or an ultrasonic disruptor.

[0075] At the outlet of the transfer tube 6, the corona discharge needle 4 makes it possible to ionize the biological material in the form of a desolvated aerosol by delivering a corona discharge. The corona discharge needle 4 is arranged in such a way that the flow of desolvated biological material at the outlet of the transfer tube 6 is transverse to the direction in which the corona discharge needle 4 points or parallel thereto, for example the angle formed by the flow of desolvated biological material and the plasma plume is from 0° to 90°, preferably from 20° to 60°, still preferably from 40° to 50°. The corona discharge is thus delivered to the flow of desolvated biological material.

[0076] The corona discharge needle 4 can be conventionally made of tungsten but can also be made purely or of an alloy of one or more metals among silver, gold, platinum, iron, nickel and lithium in order to create interactions with analytes in the gas phase. This can improve the quality of analyte detection, particularly by improving detection sensitivity.

[0077] The interface 1 may further comprise a current source 41 for powering the corona discharge needle 4 in order to deliver the corona discharge, in particular at an absolute voltage of between 2 and 10 kV.

[0078] Since the molecules of biological material have been previously separated from the aggregates of biological material at the level of the venturi system 2, the biological material desolvated by the heat provided by the heater 3 is mainly in the form of isolated molecules. This thus makes it possible to improve the ionization carried out by the corona discharge of the corona discharge needle 4.

[0079] After ionization, the ionized molecules of biological material can be transferred to the mass spectrometer for analysis. Improving the ionization of biological material by the interface increases the analysis signal of the mass spectrometer and therefore improves the performance of the system by facilitating the identification of the molecules being analyzed. Thus, the operator analyzing the signal is better able to identify the composition of biological tissues and to identify the presence or absence of pathological or abnormal elements.

[0080] Process

[0081] Reference is now made to Figure 4

[0082] 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 to a venturi system, characterized in that the method further comprises: - injection S2 of a nebulisate comprising solvent droplets into the venturi system, - S3 solvation in the venturi system of the aerosolized material in the solvent droplets of the nebulisate, - heating S4 of the mixture of solvated material in the solvent droplets of the nebulisate by a heater located around a transfer tube connected to an outlet of the venturi system leading to the desolvation of the material, and - S5 ionization of the material by a corona discharge delivered at the outlet of the transfer tube

[0083] Step S1:

[0084] Step S1 involves the delivery of biological material in aerosol form.

[0085] Biological material comes in the form of aggregates of molecules as explained above.

[0086] The flow of biological material can have a flow rate between 0.5 L / min and 5 L / min, preferably 1 L / min.

[0087] The transport of biological material can be achieved by a pressure difference generated by the venturi system.

[0088] Since the aerosolized biological material is ablated or collected from an area at atmospheric pressure, the pressure difference generated by the venturi system allows the aerosolized biological material to be drawn into the venturi system.

[0089] Step S2:

[0090] Step S2 involves injecting a nebulizer comprising solvent droplets into the venturi system.

[0091] The nebulizer is injected into the venturi system. It primes the venturi system by creating the vacuum that allows the biological material to be sucked in and transported to the venturi system.

[0092] The nebulizate comprising solvent droplets can be generated by a nebulizer, preferably a pneumatic nebulizer. A pneumatic nebulizer sprays an aerosol comprising the solvent droplets dispersed in a carrier gas. As explained previously, the carrier gas makes it possible to generate the nebulizate. The solvent can be chosen from: one or more organic solvents; one or more volatile compounds; one or more polar molecules; one or more non-polar molecules; water; and mixtures thereof. Among the organic solvents, mention may be made of 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 measuring compound (“lockmass”) or a calibration compound.

[0093] The nebulizer can be ejected at a flow rate between 100 nL / min and 2 mL / min. In some cases, the flow rate may be 100 nL / min to 500 nL / min. In other cases, the flow rate may be 100 pL / min to 2 mL / min.

[0094] The generation flow rate allows the depression created in the venturi system to be adjusted in order to modify the delivery speed of the biological material in aerosol form.

[0095] Step S3:

[0096] Step S3 involves the solvation in the venturi system of the biological material in aerosol form into the solvent droplets of the nebulisate.

[0097] The flow of biological material in aerosol form and the flow of nebulized material meet in the venturi system. The impact of the two flows, as explained above, breaks up the aggregates of biological material in order to isolate the molecules of biological material. The isolated molecules are then solvated in the solvent droplets.

[0098] Step S3 may be carried out in such a way that the flow of biological material and the flow of nebulisate are orthogonal to each other. Preferably, the nebulization inlet flow F2 and the aerosol flow F3, at their intersection, form an acute angle, for example between 10 and 80°, preferably between 20 and 50°, always preferably between 25 and 40°, for example approximately 30°. This angle may advantageously correspond to the passage slope between the first section and the third section.

[0099] As explained previously, the fact that the two flows are orthogonal allows for improved conversion of biological material aggregates into solvated biological material molecules by improving the separation of aggregates into isolated biological material molecules. [01001 Step S4:

[0101] Step S4 includes heating the solvated biological material in the solvent droplets of the nebulizate by a heater configured to heat a transfer tube connected to an outlet of the venturi system leading to desolvation of the biological material.

[0102] After solvation of the biological material molecules, the solvated biological material in the solvent droplets of the nebulizate passes through a transfer tube. This transfer tube is heated by the heater, which heats the solvated biological material molecules. The choice of heating temperature affects the proportion of biological material molecules that are desolvated. Step S4 can be carried out at a temperature between 40 and 500°C, preferably 100 and 300°C.

[0103] More generally, the flow inside the transfer tube and the temperature can be chosen so as to ensure a heat transfer between 50 and 300°C, preferably 250°C.

[0104] This temperature range makes it possible to maximize the proportion of biological material that is desolvated during step S4. The proportion of desolvated material at the end of step S4 may be between 60 and 100%, preferably between 90 and 100%. F01051 Step S5:

[0106] Step S5 involves the ionization of the biological material by a corona discharge delivered at the outlet of the transfer tube.

[0107] Following desolvation of the biological material molecules in step S4, the biological material molecules are ionized by a corona discharge delivered by a corona discharge needle at the outlet of the transfer tube. The voltage at which the corona discharge is delivered affects the proportion of desolvated biological material molecules that are ionized. The delivered corona discharge may be in absolute terms between 2 and 8 kV, preferably 5 kV.

[0108] A corona discharge delivered at this voltage maximizes the proportion of biological material molecules that are ionized during step S5.

[0109] At the end of step S5, the molecules of biological material are ionized and ready to be transferred to the mass spectrometer in order to be analyzed. 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: - a venturi system (2) with two inlets (21, 22) and one outlet (23), - a heater (3), - a corona discharge needle (4) for ionizing the material in aerosol form, characterized in that the interface further comprises: - a nebulizer (5) to generate a nebulizate, - a transfer tube (6) connected to the outlet of the venturi system, and in that: - the heater is configured to heat the transfer tube, - the corona discharge needle is located at the outlet of the transfer tube, and - the venturi system is configured to receive the aerosolized material through one of its inlets and is connected to the nebulizer through the other of its inlets, leading to solvation of the aerosolized material by the nebulizate in the venturi system.

2. Interface according to claim 1, further comprising a tube (7) for conveying the biological material in aerosol form and connected to the inlet of the venturi system receiving the latter.

3. An interface according to any preceding claim, wherein the nebulizer is a pneumatic nebulizer, the pneumatic nebulizer further comprises an emitter (51) from which the nebulizate is generated, a solvent delivery tube (520) and a gas delivery tube (530).

4. An interface according to any preceding claim, further comprising a nebulization connector (54) in which the nebulizer is arranged, the nebulization connector comprising an outlet connected to the venturi system.

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

6. An interface according to any preceding claim, wherein, in operation, the flow from the venturi system is collinear with the flow from the nebulizer.

7. Interface according to any one of the preceding claims, further comprising a current source (41) for supplying the corona discharge needle, in particular at a potential difference of between 2 and 8 kV.

8. An interface according to any preceding claim, wherein the heating cartridge is configured to deliver heat at a temperature between 40 and 500°C, preferably 100 and 300°C.

9. Method for preparing material, in particular biological material, for its transfer into a mass spectrometer comprising: - the transport (S1) of the material in aerosol form to a venturi system, characterized in that the method further comprises: - the injection (S2) of a nebulisate comprising droplets of solvent into the venturi system, - solvation (S3) in the venturi system of the material in the form of aerosol in the solvent droplets of the nebulisate, - heating (S4) the mixture of solvated material in the solvent droplets of the nebulisate by a heater located around a transfer tube connected to an outlet of the venturi system leading to the desolvation of the material, and - ionization (S5) of the material by a corona discharge delivered at the outlet of the transfer tube.

10. A method according to claim 9, wherein the nebulisate is ejected from the nebulizer at a flow rate of between 100 nL / min and 2 mL / min or between 100 pL / min and 2 mL / min.

11. A method according to any one of claims 9 to 10, wherein step (S4) is carried out at a temperature between 40 and 500°C, preferably 100 and 300°C.

12. A method according to any one of claims 9 to 11, wherein the delivered corona discharge is between 2 and 10 kV, preferably 5 kV.

Images