Quality analysis device

Abstract

The object of the present invention is to provide a mass spectrometer capable of preventing a sample from remaining in an ion source container for a long time. In the mass spectrometer of the present invention, in addition to supplying a first gas used for ionization in an ion source, a second gas is also supplied to flow along the inner wall of the ion source container toward an exhaust portion.

Description

Technical Field

[0001] The present invention relates to a mass analysis device using an ion source. Background Art

[0002] Ionization by ESI (Electrospray Ionization) is performed in the following order. The sample solution is made to flow in a capillary with a high voltage applied, the sample is sprayed from the tip of the capillary, and heated gas is blown from the periphery to make the sample solution in a spray form, thereby generating charged droplets. The charged droplets evaporate and split, thereby generating ions.

[0003] In a mass spectrometer using ions generated from an ion source, the ions are introduced into a low vacuum evacuated by a vacuum pump by means of an electric field, etc. The ions pass through an ion lens having various functions and are then guided to a quadrupole analysis unit. In the quadrupole analysis unit, there are four metal rods, to which a high-frequency voltage and a direct current voltage are applied, so that only ions having a specific ratio m / z of ion mass (m) to charge (z) are allowed to pass, thereby separating the specific ions.

[0004] The components are analyzed by detecting the separated ions with an ion detector. The quadrupole analysis unit adopts a triple structure, which is called a triple quadrupole analysis type. In this structure, mass separation is performed at the first and third stages, and induced collision dissociation (CID) is performed at the second stage.

[0005] The technology described in Patent Document 1 below includes a second gas source that supplies a second gas at a predetermined flow rate to an ionization region (a region between an ion source and a collection conduit) and supplies the second gas in a direction perpendicular to the direction in which the ion source releases the gas.

[0006] In the following patent document 2, an ESI ion source and an APCI (Atmospheric Pressure Chemical Ionization) ion source are arranged in the same ion source container, and the distance between the outlet end of the ionization probe and the heating chamber is changed by a driving device, and the two ionization methods are implemented separately, and the ESI mode and APCI mode are quickly changed, thereby achieving the throughput of the device.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2007-066903

[0010] Patent Document 2: Japanese Patent No. 6181764 Summary of the invention

[0011] Technical problem to be solved by the invention

[0012] When the sample solution cannot be discharged smoothly inside the ion source and remains for a long time, and the next sample to be analyzed is of the same type, the previous residual component amount will overlap in the analysis result, resulting in an increase in the detected signal amount. In other words, the accuracy of quantitative analysis decreases. In addition, since there are residual background components as noise, the S (signal) / N (noise) ratio changes. In addition, when the next sample to be analyzed is different from the previous sample and there is a residue of the previous sample, a sample signal that was originally impossible to exist will be detected. In other words, it will lead to erroneous detection results.

[0013] When the sample is not immediately discharged from the ion source and remains for a long time, the amount of sample inside the ion source increases, and the amount of sample flowing into the ion lens on the downstream side increases. As a result, the amount of sample attached to the ion source wall and the ion lens increases, and the maintenance cycle for removing them becomes shorter. As a result, problems such as reduced processing throughput of the device and increased maintenance costs arise.

[0014] Patent Documents 1 and 2 do not particularly consider the problem caused by the sample solution remaining in the ion source for a long time as described above. The present invention is made in view of the above problem, and its object is to provide a mass spectrometer that can prevent the sample from remaining in the ion source container for a long time.

[0015] Technical means for solving technical problems

[0016] The mass spectrometer of the present invention provides, in addition to the first gas used by the ion source for ionization, a second gas that flows along the inner wall of the ion source container toward the exhaust portion.

[0017] Effects of the Invention

[0018] According to the mass spectrometer of the present invention, the second gas is made to flow along the wall surface of the ion source container (gas curtain gas flow), which can prevent the generation of eddy currents and other circulating flows inside the ion source. Therefore, the amount of sample adhering to the wall surface can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 1 is a cross-sectional view showing the structure of the mass spectrometer 100 according to the first embodiment.

[0020] Figure 2 FIG. 1 is a schematic diagram showing simulation results of the gas flow inside the ion source of the conventional method.

[0021] Figure 3 To make the reflux less than Figure 2The simulation results of the gas flow in the ion source container 15 when the length of the exhaust pipe 18 is increased are shown.

[0022] Figure 4 Shown in Figure 2 The simulation results of the gas flow in the ion source container 15 when the concentrated exhaust pipe 45 is added to the structure of FIG.

[0023] Figure 5 It is a schematic diagram of the concentrated exhaust pipe 45.

[0024] Figure 6 1 is a diagram showing the state of gas flow inside the ion source container 15 in the first embodiment.

[0025] Figure 7 It shows that Figure 6 A diagram showing the airflow inside the ion source container 15 when the exhaust pipe 45 is concentrated is added to the structure of FIG.

[0026] Figure 8 2 is a diagram showing the structure of the gas supply member 48 .

[0027] Fig. 9 1 is a diagram showing the configuration of a mass spectrometer 100 according to the second embodiment.

[0028] Fig.10 A process flow chart illustrating the steps of checking the function of the air curtain 41 is shown. DETAILED DESCRIPTION

[0029] <Implementation method 1>

[0030] Figure 1 1 is a cross-sectional view showing the structure of a mass spectrometer 100 according to Embodiment 1 of the present invention. The mass spectrometer 100 is a device for analyzing the components of a sample using ions ionized by an ion source 3. A sample solution 1 obtained by dissolving a sample (analyte) in a solvent such as methanol or water is subjected to a pressure of several tens of MPa or less by a syringe pump 2, and is transported to a capillary 4 in the ion source 3 to which a high voltage is applied through a top tube 5. The tip of the capillary 4 is an ultrafine tube having an inner diameter of several tens to several hundred microns.

[0031] The sample solution 1 is sprayed from the front end of the capillary 4. A positive or negative voltage of several thousand volts is applied to the capillary 4. An atomizing gas tube 6 with a coaxial axis is arranged on the periphery of the capillary 4. Atomizing gas (spray gas) 7 flows in the atomizing gas tube 6 at a speed of several liters / minute. Fine droplets are generated downstream of the capillary 4, with charges of the same sign as the voltage applied to the capillary 4. An auxiliary heating gas tube 8 with a coaxial axis is also provided on the periphery of the atomizing gas tube 6. The auxiliary heating gas tube 8 is heated by a heater with a capacity of hundreds of watts not shown in the figure, and an auxiliary heating gas 9 such as nitrogen is sprayed at a flow rate of tens of liters / minute. Therefore, the vaporization and miniaturization of the droplets are further accelerated. When the surface electric field of the miniaturized droplets continues to increase and the repulsive force between the charges exceeds the surface tension of the liquid, the droplets split. Then, the ions evaporate and generate ions 10 in the ion generation area 11. The ion generation area 11 is formed in the downstream area where the sample solution 1 is sprayed.

[0032] The ions 10 are captured by the electric field of the counter plate 12, which is triangular pyramid-shaped and has holes with a diameter of several millimeters. Neutral particles other than the ions 10 and unvaporized liquid samples are also captured from the counter plate 12 to the downstream side by the flow generated by the vacuum difference. Since neutral particles other than the ions and unvaporized liquid sample solution 1 etc. may cause contamination, in order to prevent them from entering the inside of the counter plate 12 as much as possible, the reverse gas 13 is reversely flowed to the ion source 3 side at a flow rate of several liters / minute.

[0033] To minimize contamination caused by sample adhesion, the surfaces of the counter plate 12, the first fine hole 21, and the axial offset portion 22 are heated to about 200° C. by a heater (not shown). In some cases, the subsequent ion lens (eg, ion guide 25) is also heated.

[0034] The sample solution 1 etc. not captured by the counter panel 12 is discharged through the exhaust pipe 18 by the airflow of the blower 17 (19). The flow rate of the atomizing gas 7 is about 3 liters / minute, the flow rate of the auxiliary heating gas 9 is about 10 liters / minute, the flow rate of the reverse gas 13 is about 5 liters / minute, and the flow rate flowing downstream from the counter panel 12 is about 5 liters / minute, so the flow rate discharged from the blower 17 is about 13 liters / minute, which is the difference between the above. About 30% of the flow rate of the gas containing the sample solution 1 flows to the blower 17 side.

[0035] The blower 17 may have a performance (air volume-pressure loss value) with constant rotation speed, supply voltage, and frequency, or may have an exhaust performance that is changed by changing the rotation speed.

[0036] The ion source container 15, exhaust pipe 18 and blower 17 to which the sample is adhered are also originally expected to be heated to a high temperature of about 200°C to prevent the sample from adhering, but this will cause the value of the required heater capacity to become larger, and the complex structure used for the heat insulation structure will cause the device to be large-scale, and it is actually very difficult to install. Therefore, the actual situation is that the sample solution 1 will adhere to the ion source container 15, exhaust pipe 18, blower 17, etc. The sample solution 1 will separate and float after adhesion. If the component is detected, it will cause false detection due to the detection of the component that would not have been detected originally. In addition, even when analyzing the same sample type, the subsequent detection amount will also be greater than the original correct amount, so the measurement accuracy of the quantitative analysis is reduced. In addition, due to the increase in the amount of components flowing into the ion lens downstream of the panel 12, it is necessary to shorten the maintenance cycle, so the problems of increased maintenance costs and reduced device throughput have been generated.

[0037] The ion source 3 is composed of a capillary 4, a nebulizing gas tube 6, an auxiliary heating gas tube 8, a heater (not shown), a high voltage applying structure, an electrical insulator, a gas introduction structure, Figure 1 The position of the capillary tube 4 is adjusted by a stage (not shown) for adjusting the position of the capillary tube 4 by about several millimeters in the XYZ axis direction shown. The stage is used to adjust the position of the capillary tube 4 so that the performance of the device such as sensitivity is optimized. Nitrogen gas (first gas) with controlled flow rate and pressure is supplied to the atomizing gas tube 6 and the auxiliary heating gas tube 8 from a gas control unit (not shown in the figure).

[0038] The ion source 3 is fixed to the ion source container 15 by fixing the stage portion with screws. The ion source container 15 is made of metal such as aluminum or stainless steel. In order to monitor the state of the interior of the ion source container 15, a monitoring window 16 made of transparent glass, resin, etc. is provided on the side of the ion source container 15.

[0039] When replacing the consumable capillary 4 , the top tube 5 is removed and only the capillary 4 alone is replaced, or the capillary 4 and the nebulizing gas tube 6 are taken out together and replaced with new ones.

[0040] A first fine hole 21 is provided downstream of the counter plate 12. The first fine hole 21 has a hole diameter of less than 1 mm and a length of several tens of mm. The inflow amount of the first fine hole 21 is limited by the large flow resistance generated by the hole.

[0041] The axially offset portion 22 is located downstream of the first pore 21. Since the components of the sample solution 1 in a liquid state etc. travel in a straight line, they collide with the inner wall of the axially offset portion 22 and are removed. On the other hand, ions and light components flow downstream along with the air flow.

[0042] The octopole-quadrupole ion guide 25 for focusing ions is arranged downstream of the axial offset portion 22. A high-frequency potential of positive and negative oscillation is applied to the Q rod (metal or ceramic round rod) adjacent to the ion guide 25 to confine the ions 10 in the area surrounded by the Q rod. The axis of the octopole and the axis of the quadrupole are offset from each other by several millimeters in a direction orthogonal to the ion travel axis, thereby removing neutral particles and the like, and only the desired ion components move downstream under the action of the electric field in the direction of the ion travel axis.

[0043] Downstream of the ion guide 25, there is a second fine hole 26 in the shape of a plate with a thickness of several millimeters, and the second fine hole 26 has a hole with a diameter of several millimeters. By providing a plate with fine holes, chambers with different vacuum degrees are formed, and unnecessary ions are blocked by the fine hole portion, and only the required components are extracted. The first fine hole 21, the axial offset portion 22, the ion guide 25, and the second fine hole 26 are arranged in the first differential pumping chamber 23. The first differential pumping chamber 23 is evacuated by a dry pump 32 and maintained at a vacuum degree of about several hundred Pascals.

[0044] Downstream of the second fine hole 26, there is a quadrupole called an ion heater 27 (collision attenuator). Similar to the ion guide 25, a high-frequency potential of positive and negative oscillations is applied to adjacent Q rods to confine the ions 10 in the area surrounded by the Q rods. The kinetic energy of the ions 10 is reduced when they collide with the residual gas, so that the ions are concentrated near the axis of ion travel. Downstream of the ion heater 27, there is a third fine hole 28 in the shape of a flat plate with a thickness of several millimeters, and the third fine hole 28 has a hole with a diameter of several millimeters. The second fine hole 26, the ion heater 27 and the third fine hole 28 are arranged in a second differential exhaust chamber 30. The second differential exhaust chamber 30 is connected to the first exhaust port of the turbomolecular pump 29 and is maintained at a vacuum degree of several Pascals.

[0045] A triple quadrupole (mass filter) is provided downstream of the third pore 28. An ion detector composed of a triple quadrupole 31, a conversion dynode 36, a scintillator 37, an electron multiplier tube 38, etc. is arranged in the analysis chamber 33. The analysis chamber 33 is evacuated from the second exhaust port of the turbomolecular pump 29 and maintained at 1E. -3 The vacuum degree is less than Pascal. The downstream side of the turbomolecular pump 29 is connected to the dry pump 32 and exhausted. From the upstream side, the triple quadrupole 31 includes a first quadrupole, a collision chamber and a second quadrupole. The first quadrupole controls the high-frequency voltage to be applied so that only precursor ions with a specific mass-to-charge ratio (m / z) pass through. The ions 10 are guided to a collision chamber located downstream thereof and into which a collision gas (helium, nitrogen, etc.) is introduced. The ions 10 collide with the gas and break apart at the part where the chemical bond is weaker. The broken apart ions 10 are called product ions. The ions 10 are incident on the second quadrupole downstream thereof and are mass separated, thereby enabling highly sensitive quantitative analysis.

[0046] Ions 10 are incident on the conversion dynode 36 through the electric field. Ion collision generates secondary electrons, which are attracted by the electric field and incident on the scintillator 37. Photoelectrons are generated, which are amplified by the electron multiplier tube 38 and converted by the analog / digital converter 39. The mass spectrum based on the digital value is displayed on the monitor 40. The sample composition is determined by comparing it with the known data collected in advance. Through the above structure, Figure 1 The first differential pumping chamber 23 and each component provided on the downstream side thereof function as an ion measuring section.

[0047] Gas 42 (preferably an inert gas such as nitrogen) flows in from the upstream side of the ion generating area 11. The gas 42 is made to flow in from a hole or the like provided on the ion source container 15. Alternatively, a spacer is partially inserted into the mounting surface between the fixed flange of the ion source 3 and the ion source container 15, so that the gas 42 flows in from the gap between the fixed flange and the ion source container 15. The reason why nitrogen is preferred is that organic solvents such as methanol may explode and catch fire in a certain oxygen concentration region, and nitrogen is preferred to prevent this from happening. As a gas introduction position, a through hole can be provided on a part of the ion source 3 so that the gas 42 flows into the interior of the ion source container 15.

[0048] The inflow amount of gas 42 depends on (a) the flow resistance value in each part determined by the area of ​​the hole, the area of ​​the gap, the flow resistance of the gas flow, the structure inside the ion source container 15, etc., (b) the flow rate flowing from the first pore 21 to the downstream, (c) the flow rate of the atomizing gas 7, (d) the flow rate of the auxiliary heating gas 9, (e) the flow rate of the sample solution 1, and (f) the discharge capacity determined by the rotation speed of the blower 17, etc.

[0049] Once the device is manufactured, the area of ​​the hole portion, the area of ​​the gap, the shape of the ion source container 15 and the structure inside the ion source container 15 become basically determined values. In addition, the flow rate flowing from the first pore 21 to the downstream is the product of the pressure difference between the upstream (atmosphere) and the downstream of the first pore 21 and the flow conductivity value determined by the shape of the elongated hole. In addition, once the analysis conditions are determined, the flow rate of the atomizing gas 7 and the flow rate of the auxiliary heating gas 9 are also determined. In order to change the flow state of the gas 42 in the ion source container 15, it is necessary to change the inflow amount of the gas 42. To this end, it is necessary to change the rotation speed of the blower 17.

[0050] Gas 42 is made to flow in from the peripheral side (the inner wall surface side of ion source container 15) of ion generating region 11, and flows toward exhaust pipe 18 along the inner wall surface of ion source container 15 as air curtain 41. Air curtain 41 mainly flows to the outside of ion generating region 11. The reason for flowing to the outside is: because ion generating region 11 contains a large amount of ions 10 and sample solution 1, it will interfere with the flow in this area, and it is likely to reduce the sensitivity of the device. In addition, the gas flows to the inner wall of ion source container 15, and the amount of sample adhering to the inner wall of ion source container 15 increases, and the occurrence of the bad problem recorded is also one of the reasons.

[0051] Figure 2 It is a schematic diagram of the simulation result of the flow inside the ion source of the existing method. The dotted arrow in the figure indicates the direction of the airflow 44. The length of the arrow is not proportional to the flow rate. The calculation conditions are that the flow rate of the atomizing gas 7 is 2 liters / minute, the flow rate of the auxiliary heating gas 9 is 10 liters / minute, and the flow rate of the reverse gas 13 is 5 liters / minute. The flow rate flowing out from the first pore 21 is about 5 liters / minute. The discharge of the blower 17 is about 12 liters / minute. The flow rate at the outlet of the atomizing gas pipe 6 is about 380 meters / second, which exceeds the speed of sound. The flow rate at the outlet of the auxiliary heating gas pipe 8 is about 4 meters / second, which is about 100 times different. The distance from the atomizing gas pipe 6 to the ion source container 15 is tens of millimeters. If it is assumed that the flow rate at the outlet of the atomizing gas pipe 6 remains unchanged, it will reach the inner wall of the ion source container 15 in less than 1 millisecond. In such a short time, a part of the ions are captured inside the counter plate 12 under the action of the electric field.

[0052] The gas containing the sample solution 1 collides with the lower part of the exhaust pipe 18, generates a backflow, and forms a circulating flow (vortex) 43. The gas containing the sample solution 1 collides with the low temperature part having a temperature lower than about 200° C., namely, the ion source container 15 and the monitoring window 16, and a part of the gas adheres to the ion source container 15 and the monitoring window 16. A part of the sample solution 1 is continuously provided to the circulating flow (vortex) 43, so that the sample adheres to the inner surface of the ion source container 15 for a long time.

[0053] and Figure 2 compared to, Figure 3 The simulation results of the flow in the ion source container 15 are shown in the case where the exhaust pipe 18 is lengthened to reduce backflow. By extending the length of the exhaust pipe 18, the flow rate of the gas containing the sample is reduced in the lower part of the exhaust pipe 18, and backflow is less likely to occur. However, since the size of the device is limited, the length of the exhaust pipe 18 is limited. Figure 3 In the structure, although the recirculation area is reduced, the circulation flow (eddy current) 43 still exists. Figure 2Similarly, the sample will adhere to the ion source container 15. Although the amount of adhesion can be reduced, the above-mentioned problem still occurs.

[0054] Relative to Figure 2 The structure, Figure 4 The simulation result of the flow in the ion source container 15 is shown in the case where the centralized exhaust pipe 45 is added. The centralized exhaust pipe 45 can reduce the backflow caused by the collision of the gas with the lower part of the exhaust pipe 18, but a part of the gas containing the sample solution 1 collides with the centralized exhaust pipe 45, generating the circulating flow (vortex) 43 shown in the figure. During the calculation, two circulating flows (vortices) 43 are generated as shown in the figure. Figure 2 Similarly, a portion of the sample solution 1 is continuously supplied to the circulating flow (vortex) 43 , and the sample adheres to the inner surface of the ion source container 15 for a long time.

[0055] Figure 5 Schematic diagram of the centralized exhaust pipe 45. The centralized exhaust pipe 45 is a metal pipe having an outermost diameter of about 30 mm and a height of about 60 mm, and the diameter of the front end becomes smaller and tapered. The centralized exhaust pipe 45 is arranged near the counter panel 12. When various sample solutions 1 are used for analysis, part of the sample solution 1 adheres to the centralized exhaust pipe 45. Once adhered, it will cause erroneous detection, so it is insulated and heated by a heater to keep the centralized exhaust pipe 45 at a high temperature.

[0056] Figure 6 1 is a diagram showing the flow inside the ion source container 15 in Embodiment 1. The gas 42 flows in at a flow rate of 20 liters / minute. Other calculation conditions are the same as Figure 2 A portion of the gas 42 flows along the inner wall of the ion source container 15 to form a gas curtain 41. The gas curtain 41 serves to Figure 2 The circulation flow (eddy current) 43 shown has the effect of pushing the sample toward the downstream side. Therefore, the amount of the sample adhering to the inner wall surface of the ion source container 15 can be reduced, and the problem caused by the adhering can be solved.

[0057] Figure 7 It shows the Figure 6 The flow of the gas 42 is related to the flow of the gas 42 in the ion source container 15 when the exhaust pipe 45 is concentrated. Figure 6 The same as 20 liters / minute. Other calculation conditions are the same as Figure 2 The gas inlet of the concentrated exhaust pipe 45 is arranged at a position extending the central axis of the ion source 3 . Figure 4 The branched circulating flow (eddy flow) 43 shown becomes smaller. In addition, the air flow does not reach the inner wall of the ion source container 15. Therefore, the problem caused by the adhesion of the sample can be solved.

[0058] Figure 8 This is a diagram showing the structure of the gas supply member 48. The gas supply member 48 is a member for uniformly radiating the gas 42, and is disposed at the inlet portion where the gas 42 flows into the ion source container 15. The gas 42 enters the inlet hole 47 of the gas supply member 48 from a gas source 52 such as a nitrogen gas cylinder through a mass flow controller 51 (gas supply device), and is supplied into the ion source container 15 at a required pressure and flow rate. The gas 42 diffuses inside the gas supply member 48. A plurality of outlet holes 49 having a diameter smaller than that of the inlet hole 47 are provided on the lower surface of the gas supply member 48. The number of the outlet holes 49 is larger than the number of the inlet holes 47.

[0059] When replacing the flow path resistance of the gas supply member 48 with an equivalent circuit, as Figure 8 shown in the lower right figure of. The gas flow velocity corresponds to the energized current value I, and the difference between the gas pressure supplied from the mass flow controller 51 and the pressure inside the ion source container 15 corresponds to the potential difference V. R1 is the flow path resistance value in the inlet hole 47, R2n (n = 1, 2,..., n) are the flow path resistance values in each partition inside the gas supply member 48, and R3m (m = 1, 2,..., m) are the flow path resistance values in the outlet holes 49. By reducing the aperture diameter of the outlet holes 49 or making the flow path slender, the flow path resistance value of R3m becomes larger (the flow conductance becomes smaller). By R1, R2n << R3m, V31 (the gas outlet flow velocity in each partition) ≈ V32 ≈... ≈ V3m << V1 (the inlet flow velocity), and the outflow velocity at each gas outlet of the gas supply member 48 can be made uniform. That is, the gas 42 can be radiated in a shower shape.

[0060] Radiating the gas in a shower shape and uniformly is to generate a gas curtain 41 flow with less turbulence in the ion source container 15. A laminar flow is preferably formed. When there is turbulence, the sample adhering to the inner wall of the ion source container 15 is likely to detach, and the above-mentioned problems are likely to occur. Therefore, the gas curtain 41 is preferably a laminar flow with less turbulence.

[0061] The gas source 52, the mass flow controller 51, the gas supply member 48, and the inlet hole for installing the gas supply member 48 serve as a gas supply section (second gas supply section) for supplying the gas 42 into the ion source container 15. The discharge port (outlet hole 49) of the gas 42 is disposed on the upstream side of the ion generation region 11 in the gas flow direction and outside the central axis of the ion source 3 (on the side close to the inner wall of the ion source container 15). Similarly, the inlet hole, gas source, etc. for supplying the atomizing gas 7, etc. serve as a gas supply section (first gas supply section) for supplying these gases to the ion source 3.

[0062] <Embodiment 1: Summary>

[0063] In the mass spectrometer 100 of the first embodiment, the gas 42 is made to flow toward the exhaust pipe 18 along the inner wall of the ion source container 15. Thus, the circulating flow 43 of the sample solution 1 can be suppressed, and the sample can be discharged smoothly. Thus, the sample solution 1 can be suppressed from adhering to the inner wall of the ion source container 15, etc., and the residence time of the residual sample inside the ion source container 15 can be shortened. Therefore, when the same sample is continuously analyzed, the residual time and residual amount of the sample are reduced, thereby improving the accuracy of quantitative analysis and improving the S / N ratio (signal-to-noise ratio).

[0064] According to the mass spectrometer 100 of the first embodiment, even when analyzing different samples, the influence of the previous sample can be reduced, and the risk of false detection and false judgment can be reduced. In addition, the amount of dirt adhering to the downstream ion lens can be minimized, and the maintenance cycle can be extended. Therefore, the processing throughput of the device can be improved, and the maintenance cost for a certain period (for example, every year) can be reduced.

[0065] In the first embodiment, the flow rate of the gas curtain 41 is slower than the flow rate of other gases such as the atomizing gas 7 by the gas supply means 48. The flow rate of the gas curtain 41 can be similarly reduced by adjusting the flow rate of the gas 42 by the mass flow controller 51 described later.

[0066] <Implementation method 2>

[0067] Fig. 9 This is a structural diagram of a mass spectrometer 100 according to a second embodiment of the present invention. The ion source container 15 is in a cylindrical shape having an axis in the axial direction of the counter plate 12. A flat portion is provided on the cylindrical shape, and the ion source 3 is mounted on the flat surface. In this second embodiment, in addition to the structure described in the first embodiment, a guide plate 55 is further provided. The guide plate 55 is bent along the inner circumference of the cylinder of the ion source container 15, thereby guiding the air curtain 41 along the inner wall of the ion source container 15. The guide plate 55 has a flat portion for fixing and an R surface along the inner wall of the ion source container 15. The flat portion of the guide plate 55 is fixed to the ion source container 15, for example, by screwing. The other structures are the same as those in the first embodiment.

[0068] According to the mass spectrometer 100 of the second embodiment, the gas curtain 41 can flow along the inner wall of the ion source container 15 by the guide plate 55. Thus, the gas curtain 41 can reliably avoid the ion generation region 11, and thus can avoid hindering the ion generation action in the ion generation region 11.

[0069] <Implementation method 3>

[0070] The flow rate of the sample solution 1, the temperature of the ion source 3, the flow rate of the atomizing gas 7, the flow rate of the auxiliary heating gas 9, the flow rate of the reverse gas 13, etc., which are analysis conditions, differ depending on the object of analysis. Therefore, the airflow in the ion source container 15 is different for each object of analysis. Depending on the different conditions, a circulating flow (vortex) 43 is generated, and the problems caused by this can be anticipated. Therefore, in embodiment 3 of the present invention, the action steps for checking whether the gas curtain 41 is fully effective are described. The structure of the mass spectrometer 100 is the same as that of embodiments 1 to 2.

[0071] Fig.10 A process flow chart illustrating the steps for checking the function of the air curtain 41 is shown. Fig.10 Describe each step.

[0072] First, the mass spectrometer 100 is used to analyze the sample A (step 1). As a result of the analysis, a detection signal distribution corresponding to the sample A is obtained. Next, the sample B is analyzed (step 2). Here, it is assumed that a residual component of the sample A exceeding the threshold value (judgment value) is detected. The residual component is considered to be caused by the generation of a circulating flow (eddy current) 43 inside the ion source container 15.

[0073] The mass flow controller 51 increases or decreases the inflow of the gas 42, or when the inlet of the gas 42 is opened to the atmosphere, increases or decreases the rotation speed of the blower 17 (step 3). Both can also be implemented. Thus, the flow rate of the air curtain 41 inside the ion source container 15 is changed. Thereafter, the residual amount of the sample A is confirmed again. The operation of changing the flow rate of the air curtain 41 is repeated until the residual amount of the sample A becomes below the threshold value (judgment value) (step 4).

[0074] Since sample A will flow to the downstream side even if it is left, the detection amount will continue to decrease. Therefore, even if the residual amount of sample A is below the threshold, this may be caused by the operator taking time to execute steps 3 to 4. Therefore, a re-inspection is performed under the same conditions (step 5). When the residual amount of sample A is not lower than the threshold, return to step 3 and repeat the same steps. Even if the re-inspection is repeated a specified number of times, if the residual amount of sample A still does not reach below the threshold, it is considered that the device is abnormal or the inside of the ion source container 15 has been contaminated, so an alarm is issued and the mass spectrometer 100 is stopped.

[0075] If the residual amount of sample A is below the threshold, it is determined that the generation of the circulating flow (eddy current) 43 inside the ion source container 15 is suppressed, and the analysis is performed (step 6). Through the above steps, the air curtain 41 is reliably activated, and the influence of residue and cross contamination is suppressed, so that high-precision analysis can be performed.

[0076] <Variations of the present invention>

[0077] In the above embodiment, the outlet holes 49 of the gas supply member 48 do not have to be arranged at equal intervals. For example, the number of outlet holes 49 can be increased at a location where more air curtains 41 are to flow. Similarly, the number of outlet holes 49 can be increased at a location where the flow rate of the air curtain 41 is to be slowed down.

[0078] In the above embodiment, the ion source 3 using the electrospray ionization method is described as the ionization method, but other ion sources 3 using atmospheric pressure chemical ionization, chemical ionization (CI method), electron impact ionization (EI method), etc. can also be used. As the ion source 3, an ECR (microwave) plasma ion source, an inductively coupled plasma ion source, a Penning ion source, a laser ion source, etc. can be used.

[0079] In the above embodiment, a quadrupole mass spectrometer is exemplified as the mass spectrometer 100 , but a time of flight mass spectrometer (TOF / MS), a Fourier transform ion cyclotron resonance mass spectrometer, or a magnetic sector mass spectrometer may also be used.

[0080] Description of symbols

[0081] 1. Sample solution

[0082] 2 Syringe Pump

[0083] 3 Ion source

[0084] 4 Capillary

[0085] 5 Pipe jacking

[0086] 6 Atomizing gas tube

[0087] 7 Atomizing gas

[0088] 8 Auxiliary heating gas pipe

[0089] 9 Auxiliary heating gas

[0090] 10 Ions

[0091] 11 Ion generation area

[0092] 12 pairs of panels

[0093] 13 Reverse Gas

[0094] 15 Ion source container

[0095] 16 Monitoring Window

[0096] 17 Blower

[0097] 18 Exhaust pipe

[0098] 19 Exhaust

[0099] 21 First pore

[0100] 22 Axial offset

[0101] 23 First differential exhaust chamber

[0102] 24 Dry Pump

[0103] 25 Ion guide

[0104] 26 Second pore

[0105] 27 Ion Heater

[0106] 28 The third pore

[0107] 29 Turbomolecular pump

[0108] 30 Second differential exhaust chamber

[0109] 31 Triple Quadrupole

[0110] 32 Dry Pump

[0111] 33 Analysis Room

[0112] 36 Conversion dynode

[0113] 37 Scintillator

[0114] 38 Electron Multiplier Tube

[0115] 39 Analog / digital converter

[0116] 40 Monitor

[0117] 41 Air curtain

[0118] 42 Gas

[0119] 43 Circulation (vortex)

[0120] 44 Airflow

[0121] 45 Central exhaust pipe

[0122] 48 Gas supply component

[0123] 47 Entrance hole

[0124] 49 Exit hole

[0125] 51 Mass Flow Controller

[0126] 52 Gas Source

[0127] 55 Guide plate.

Claims

1. A mass analysis device, characterized in that: include: an ion source, the ion source generating ions; a container, the container being used to contain the ion source; a first gas supply unit, which supplies a first gas used for the ion source to generate the ions to the ion source; an exhaust portion, the exhaust portion being used to exhaust the first gas from the container; as well as a second gas supply portion, the second gas supply portion supplying a second gas, the second gas flowing inside the container and outside the ion source along the inner wall of the container toward the exhaust portion, The exhaust portion includes an exhaust pipe that tapers gradually from the exhaust portion toward the ion source as a structure for reducing backflow toward the ion source side. The gas inlet of the exhaust pipe is arranged at a position extending the central axis of the ion source.

2. The mass spectrometer according to claim 1, wherein: In the direction of the flow of the first gas, the outlet of the second gas supply unit for discharging the second gas is arranged on the upstream side of the outlet of the ion source for discharging the first gas. The second gas supply portion supplies the second gas so that the second gas flows from the upstream side toward the exhaust portion.

3. The mass spectrometer according to claim 2, wherein: The second gas supply portion is composed of a member having an inlet hole for introducing the second gas and an outlet hole for discharging the second gas. The outlet hole is provided outside an ejection port through which the first gas is ejected in the ion source, when viewed from the center of the ion source on a plane perpendicular to a flow path through which the first gas passes inside the ion source.

4. The mass spectrometer according to claim 3, wherein: The flow resistance generated by the outlet hole is greater than the flow resistance generated by the inlet hole.

5. The mass spectrometer according to claim 4, wherein: The number of the outlet holes is greater than the number of the inlet holes.

6. The mass spectrometer according to claim 4, wherein: The aperture of the outlet hole is smaller than the aperture of the inlet hole.

7. The mass spectrometer according to claim 4, wherein: The flow path length of the outlet hole is greater than the flow path length of the inlet hole.

8. The mass spectrometer according to claim 1, wherein: The mass analysis device further includes a gas supply device for supplying the second gas, The gas supply device supplies the second gas in such a manner that a flow rate of the second gas is lower than a flow rate of the first gas.

9. The mass spectrometer according to claim 1, wherein: The mass analysis device further includes a guide plate for guiding the second gas along an inner wall of the container.

10. The mass spectrometer according to claim 9, wherein: The side wall of the container has a curved shape, The guide plate is bent to guide the second gas along the bent shape.

11. The mass spectrometer according to claim 1, wherein: The mass spectrometer further includes a measuring unit that uses the ions to measure an amount of a substance contained in the sample. The mass spectrometer further includes a control unit configured to control at least one of a flow rate of the second gas and an exhaust volume from the exhaust unit. The measuring unit measures a first sample containing a first substance and then measures a second sample containing a second substance. When the measurement result of the second sample by the measuring unit detects that the first substance is equal to or greater than a threshold value, the control unit performs at least one of increasing the flow rate of the second gas or increasing the exhaust volume from the exhaust unit.

12. The mass spectrometer according to claim 11, wherein: The control unit repeatedly performs at least one of increasing the flow rate of the second gas or increasing the exhaust volume from the exhaust unit until the amount of the first substance detected by the measuring unit is less than the threshold value. When the amount of the first substance detected by the measuring unit is less than the threshold value, the measuring unit remeasures the second sample after remeasures the first sample, When the first substance is detected to be equal to or greater than a threshold value in the measurement result of the second sample obtained by the re-measurement, the control unit performs at least one of increasing the flow rate of the second gas or increasing the exhaust volume from the exhaust unit.

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