Patent Publication Number: US-2023141083-A1

Title: Ion source, mass spectrometer, ion source control method

Description:
TECHNICAL FIELD 
     The present invention relates to an ion source that ionizes a sample. 
     BACKGROUND ART 
     Electrospraying (in the following, referred to as “ESI method”), which is a typical ionization method for use in mass spectrometric analysis and the like, is a method in which a sample liquid solution is introduced from the upstream end of a capillary and ions or droplets are sprayed from a downstream end using an electric field and the like. In order to improve ionization efficiency, in some cases, a gas spray pipe is disposed on the outer side of a capillary to spray a gas or a heated gas is sprayed to ions or droplets sprayed from the capillary. 
     Since the inner diameter of the capillary is a considerably small diameter, this is highly likely to cause clogging, and thus the capillary has to be frequently exchanged depending on types, use conditions, or the like of a sample liquid solution. However, the capillary exchange operation of conventional ESI ion source is complicated, and the reproducibility of the position of the downstream end of the capillary after exchanged affects the reproducibility of the detection sensitivity. This is because the position of the downstream end of the capillary with respect to the ion inlet port of a mass spectrometer greatly affects detection sensitivity. 
     Patent Literature 1 below describes a technique that adjusts the position of the downstream end of a capillary. In this literature, a capillary is secured to a joint in advance to integrate those members, the joint is rotated and screwed into a manifold, so that the capillary is movable in the longitudinal direction (the position of the downstream end of the capillary can be adjusted in a state in which the capillary is installed in a housing) (see Abstract of the present literature). 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2008-021455 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     The method described in Patent Literature 1 is the technique that is suited to optimizing a position while observing the sensitivity of ions produced by actual flowing of a sample liquid solution. This technique is not possible to determine whether the position is optimum before producing ions. As a result, a reduction in throughput or a loss of a sample occurs. 
     Moreover, in a case in which a capillary is exchanged by taking out and putting in, a possibility may be thought that the capillary is caught at the part in the midway point (e.g., in the inside of a gas spray pipe) at the time of insertion because the capillary has a small diameter and the downstream end of the capillary does not reach a desired position (e.g., at a position at which the downstream end of the capillary slightly projects from the downstream end of a gas spray pipe). When a sample liquid solution is delivered in this state, the inside of the gas spray pipe is soaked, which might be a cause of a trouble for contamination or failure of the analyzer. 
     Although the degree of projection of the capillary can be visually confirmed to some extent, the position resolution which can be visually obtained is limited. A method is also considered in which a camera, sensor, or the like is disposed and the position of the downstream end of the capillary is managed. However, such method leads to an increase in size and complication of the analyzer. Moreover, in the ESI ion source, ions or droplets sprayed from the downstream end of the capillary are heated with a heated gas and the like in order to improve ionization efficiency. Thus, since the temperature of the surrounding of the ion source becomes high temperature, disposing a camera or a sensor near the ion source is not realistic. 
     The present invention is made in view of the problems described above, and an object of the present invention is to provide an ion source and a control method therefor that can accurately and efficiently identify whether a tip end position on a capillary downstream side is proper. 
     Solution to Problem 
     The ion source according to the present invention measures an electric current generated due to the application of a voltage to a capillary by a power supply when a sample is not introduced into the capillary. When the electric current is within an acceptable range, the ion source outputs projection amount information expressing that the projection amount of the capillary is proper, and the ion source outputs the projection amount information expressing that the projection amount is improper when the projection amount is not within the acceptable range. 
     Advantageous Effects of Invention 
     In accordance with the ion source according to the present invention, it is possible to accurately and efficiently identify whether the tip end position on the capillary downstream side is proper with no degradation in analysis throughput. Accordingly, the reproducibility of the capillary tip end position is improved, and it is possible to achieve high analysis reproducibility. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a configuration diagram of a mass spectrometer  1  according to a first embodiment; 
         FIG.  2    is a flowchart that describes procedures of exchanging a capillary  11 ; 
         FIG.  3    is a diagram of an example in which a liquid chromatograph (LC) is combined with the mass spectrometer  1 ; 
         FIG.  4    is a chart that describes the timing of exchanging a capillary; 
         FIG.  5    is a diagram of examples of functions that determines an exchangeable state or an analyzable state; 
         FIG.  6    is a diagram showing an exemplary configuration for a preparatory experiment used for confirming differences in current values due to the position of the downstream end  12  of the capillary  11 ; 
         FIG.  7    is a graph showing a result in which the current value of an electric current carried through a counter electrode is monitored by an ammeter when Zneb is fixed and the projection amount (L) of the capillary  11  is changed; 
         FIG.  8    is a graph plotting current values when Zcapi is fixed at one millimeter intervals ranging from five to twelve millimeters and the projection amount (L) of the capillary  11  is changed; 
         FIG.  9    is a graph showing a result in which current values are plotted for every condition under which L is constant and Zcapi is changed; 
         FIG.  10    is a configuration diagram of an ion source  2  according to a second embodiment; 
         FIG.  11    is a flowchart that describes procedures of exchanging a capillary  11  in the second embodiment; 
         FIG.  12    is a configuration diagram of an ion source  2  according to a third embodiment; 
         FIG.  13    is a configuration diagram of an ion source  2  according to a fourth embodiment; 
         FIG.  14    is a configuration diagram of an ion source  2  according to a fifth embodiment; 
         FIG.  15    is a configuration diagram of an ion source  2  according to a sixth embodiment; 
         FIG.  16    is a configuration diagram of an ion source  2  according to a seventh embodiment 
         FIG.  17    is a flowchart that describes capillary exchanging procedures according to an eighth embodiment; 
         FIG.  18    is a graph that describes a range of I 3 ≤I≤I 4 ; 
         FIG.  19    is a flowchart that describes capillary exchanging procedures according to a ninth embodiment; 
         FIG.  20    is a graph showing an example that compares a reference profile with a measured result; 
         FIG.  21    is a graph showing an example that compares a reference profile with a measured result; 
         FIG.  22    is a graph showing an example that compares a reference profile with a measured result; 
         FIG.  23    is a flowchart that describes operation procedures of an ion source  2  according to a tenth embodiment; and 
         FIG.  24    is graph showing an example of a result of repeatedly measuring current values. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
       FIG.  1    is a configuration diagram of a mass spectrometer  1  according to a first embodiment of the present invention. The mass spectrometer  1  includes an ion source  2 , a vacuum chamber  4 , and the like. The vacuum chamber  4  has a mass spectrometric analyzer  3  and the like in the inside of the vacuum chamber  4 . The ion source  2  is mainly formed of an ion producer  5  and an ion source chamber  6 . 
     Ions produced by the ion source  2  are introduced from a hole  8  of a leading-in electrode  7  into the vacuum chamber  4 , and are analyzed by the mass spectrometric analyzer  3 . To the mass spectrometric analyzer  3 , various voltages are applied from a power supply  9 . The timing of applying a voltage by the power supply  9  and voltage values thereof are controlled by a controller  10  (computation unit). In addition to these, the controller  10  can also control components included in the ion source  2  or components included in the mass spectrometer  1 . 
     In the ion producer  5 , a sample liquid solution is introduced into a capillary  11 , and ions or droplets are sprayed from a downstream end  12  of the capillary  11  by an electric field and the like. The voltage value to be applied to the capillary  11  is typically about a few kV (absolute value). In a case in which positive ions are produced, a voltage of a few positive kV is applied to the capillary  11 . In a case in which negative ions are produced, a voltage of a few negative kV is applied to the capillary  11 . Although the flow rate of the sample liquid solution depends on the inner diameter of the capillary  11 , generally, the flow rate is set in the range of order of nL/min to mL/min. Although depending on the conditions for the flow rate of the sample liquid solution and the like, the inner and outer diameters of the capillary  11  are both set to about one millimeter or less. 
     In order not to leak, to the outside of the analyzer, droplets that are not introduced into the vacuum chamber  4  or components that are made of vaporized droplets, in some cases, the area between the ion source chamber  6  and the vacuum chamber  4  is set to a sealed state (or a state close to a sealed state). Furthermore, an air outlet port  13  may be provided, which evacuates these extra components and the like. In order to observe the spray state of the downstream end  12  of the capillary  11 , a window  14  may be provided, which is formed of a transparent member such as glass, on a part of the ion source chamber  6 . 
     As shown in  FIG.  1   , the inside of the vacuum chamber  4  is sometimes partitioned by a plurality of vacuum chambers  15 ,  16 , and  17 . The vacuum chambers are connected through holes  18  and  19  having a small diameter. The hole  8  of the leading-in electrode  7  and these holes  18  and  19  are paths for ions, and a voltage may be applied to the members having these holes. In this case, these members have to be insulated from a housing such as the vacuum chamber  4  through an insulator (not shown). The number of the vacuum chambers may be larger or smaller than the number in  FIG.  1   . 
     The vacuum chambers  15 ,  16 , and  17  are generally evacuated with vacuum pumps  20 ,  21 , and  22 , and maintained at about a few hundreds Pa, about a few Pa, and 0.1 Pa or less, respectively. In the vacuum chamber  16 , an ion transport unit  23  that transmits ions while converging ions is provided. As the ion transport unit  23 , a multipole electrode, an electrostatic lens, or the like may be used. In some cases, the ion transport unit  23  is disposed in other vacuum chambers such as the vacuum chamber  15  or  17 , or the like. To the ion transport unit  23 , a radio frequency voltage, a direct current voltage, an ac voltage, and the like, and in addition to these voltages, a voltage combining these voltages and the like are applied. 
     The mass spectrometric analyzer  3  is formed of an ion analyzer  24 , a detector  25 , or the like. The ion analyzer  24  separates or dissociates ions. As the ion analyzer  24 , an ion trap, quadrupole filter electrode, collision cell, time-of-flight mass spectrometer (TOF), and the like, and in addition to these, a configuration combining these devices and the like can be used. Ions passing through the ion analyzer  24  are detected by the detector  25 . As the detector  25 , an electron multiplier, a multichannel plate (MCP), and the like can be used. The ions detected by the detector  25  are converted into electrical signals and the like, and the controller  10  analyzes in detail information on the mass or strength of the ions using these electrical signals. The controller  10  includes an input-output unit that accepts an instruction input from a user and that controls the voltage and the like, and also includes a memory and the like. The controller  10  also has software necessary to operate the power supply. As the voltage to be supplied from the power supply  9  to the mass spectrometric analyzer  3 , a radio frequency voltage, a direct current voltage, an ac voltage, and the like can be used, and in addition to these, a voltage combining these voltages and the like can be used. 
     In the configuration of  FIG.  1   , a counter electrode  26  is disposed in the previous stage of the leading-in electrode  7 . A gas is carried between the leading-in electrode  7  and the counter electrode  26  to spray the gas from a hole  27  of the counter electrode  26 , and thus it is possible to suppress the entrance of noise components such as excess droplets and the like sprayed from the downstream end  12  of the capillary  11  into the hole  8  of the leading-in electrode  7 . Generally, the flow rate of the gas is set to about 0.5 to 10 L/min, and an inert gas such as nitrogen or argon is used. Generally, the diameter of the hole  27  of the counter electrode  26  is 1 mm or more, and the applied voltage is about a few positive or negative kV at the maximum. 
     In the configuration of  FIG.  1   , the gas spray pipe  28  is disposed around the capillary  11 , a gas is carried between the capillary  11  and the gas spray pipe  28 , and sprayed from the downstream end  29  of the gas spray pipe  28 . Accordingly, the vaporization of the droplets sprayed from the downstream end  12  of the capillary  11  is promoted, and it is possible to improve ionization efficiency. Generally, the flow rate of the gas is set to about 0.5 to 10 L/min, and an inert gas such as nitrogen or argon is used. Generally, the inner diameter of the downstream end  29  of the gas spray pipe  28  is set to about one millimeter or less. 
     In order to further improve ionization efficiency, the space in which ions or droplets are sprayed from the downstream end  12  of the capillary  11  may be heated with a heated gas (at a temperature of about 800° C. at the maximum) (not shown). Generally, the flow rate of the heated gas is set to about 0.5 to 50 L/min, and an inert gas such as nitrogen or argon is used. 
     The capillary  11  is fixed to a connector  30  through a sealing unit (not shown) such as a packing, an O-ring, and a ferule. The capillary  11  and the connector  30  may be integrated with each other by bonding, welding, brazing, and the like. In a case in which a gas is carried between the capillary  11  and the gas spray pipe  28 , a sealing material  31  that seals the gas may be preferably disposed. In  FIG.  1   , although the sealing material is an area seal, the sealing material may be another configuration such as a shaft seal as long as hermeticity can be maintained. As the sealing material  31 , a ring such as an O-ring, a packing, a resin, and rubber can be used. 
     The connector  30  has a pipe (not shown) connecting unit  32 , and a pipe can be connected to the connector  30  through the pipe connecting unit  32 . The sample liquid solution is supplied to the pipe, and thus a sample is supplied to the capillary  11 . 
     The capillary  11  is exchanged due to the clogging and the like of the capillary  11  (here, the capillary  11  is exchanged in the state in which the capillary  11  is fixed to the connector  30 ), and then the surfaces of the connector  30  and the gas spray pipe  28  contact with each other as shown in  FIG.  1   . Thus, in the case in which the difference in the length of the capillary  11  between analyzers is small, the position of the downstream end  12  in the Z-direction is supposed to be reproduced. However, the downstream side of the gas spray pipe  28  is often made narrow in order to accelerate the velocity of a gas to be sprayed. There is a possibility that unlike  FIG.  1   , the capillary  11  having a considerably small diameter does not reach a predetermined position at which the capillary  11  slightly projects from the downstream end  29  of the gas spray pipe  28  due to the capillary  11  being caught in the midway point, for example. When a sample is delivered in the state in which the downstream end  12  of the capillary  11  remains in the inside of the gas spray pipe  28 , the inside of the gas spray pipe  28  is soaked, which might be a cause of a trouble for contamination or failure of the analyzer. 
     Therefore, the first embodiment is provided with an ammeter  34  that monitors a value of a current carried through the counter electrode  26  when a voltage is applied from a power supply  33  to the capillary  11  after the capillary  11  is exchanged. The controller  10  determines the position of the downstream end  12  of the capillary  11  according to the monitored current value, and determines whether analysis is executed or stopped depending on the result. In the case in which analysis is stopped, an alert is presented using an indicator  35  or any other device, for example. As the alert, various devices may be such as a monitor, a lamp, and a display, which are visual, and a buzzer and a siren, which is auditory, and the like. 
       FIG.  2    is a flowchart that describes procedures of exchanging the capillary  11 . After a new capillary  11  is set at the time of exchanging the capillary  11 , a value of a current carried through the counter electrode  26  is monitored by the ammeter  34 . The controller  10  determines whether the position of the downstream end  12  of the capillary  11  is at a normal position according to a measured result. The controller  10  outputs projection amount information expressing whether the position of the downstream end  12  of the capillary  11  is at the normal position according to the determined result. The projection amount will be described with reference to  FIGS.  6  to  9    described later. When the downstream end  12  is at the normal position, analysis is executed, whereas in the case in which it is not possible to determine that the downstream end  12  is at the normal position, the controller  10  outputs an alert with the indicator  35 . 
     When actually determining whether the downstream end  12  is at the normal position, in many cases, a current value range to some extent is accepted. For example, in the case in which a current value (I) measured at the normal position is 30 μA plus or minus 2 μA, the range of fluctuations from a minimum value (I 1 )=28 μA to a maximum value (I 2 )=32 μA is accepted, i.e., the condition of I 1 ≤I≤I 2  can be set to the acceptable range. The acceptance condition is one example, and the range of acceptance may be set to a broader range or a narrower range using different conditional expressions. In the case in which the position of the downstream end  12  is not acceptable and an alert is outputted, the capillary  11  is again installed. In the case in which the position of the downstream end  12  is not acceptable repeatedly for many times, it may be determined that the component itself causes an error and the capillary  11  may be exchanged for a new capillary  11 . 
       FIG.  3    is an example in which a liquid chromatograph (LC) is combined with the mass spectrometer  1 . Generally, the mass spectrometer  1  is often used in combination with a liquid chromatograph (LC)  37  as in  FIG.  3   . The LC  37  is mainly formed of pumps  38  and  39 , a mixer  40 , a sample injection unit  41 , a separation column  42 , and the like. A sample injected into the sample injection unit  41  are delivered by the pumps  38  and  39 , and delivered to the separation column  42  by moving phases  43  and  44  mixed by the mixer  40 . The mixing ratio at the mixer  40  is adjustable according to the flow ratios of the pumps  38  and  39 . For the moving phases  43  and  44 , water (or a solvent whose principal component is water) is used for one, and an organic solvent such as methanol or acetonitrile (or a solvent whose principal component is an organic solvent) is used for the other. Generally, in the LC  37 , a sample is injected into the separation column  42  that is washed and balanced with water, an organic solvent, or the like used in the moving phases  43  and  44 , and then sample components are eluted from the separation column  42  by the moving phase  43  or  44 , or by a liquid solution having both moving phases mixed. In elution, the mixing ratio of the moving phases  43  and  44  is temporally changed, and the LC peaks of the sample components can be hourly acquired (LC separation). The ion source  2  is disposed on the downstream of the LC  37  as in  FIG.  3   , the sample corresponding to the LC peak is hourly ionized, and the ions of the sample are analyzed by the mass spectrometer  1 . The timing (holding time) of the LC peak corresponding to the sample component can be uniquely defined from the type of the separation column  42 , the mixing ratios of the moving phases  43  and  44 , the length of the pipes, and the like. 
       FIG.  4    is a chart that describes the timing of exchanging the capillary. In the system in  FIG.  3   , in the process of delivery to the capillary  11  by the pumps  38  and  39 , pressure abnormality due to the clogging of the capillary  11 , a reduction on sensitivity due to the degradation of the downstream end  12  of the capillary  11 , and the like possibly occur. In the case in which such a phenomenon occurs, generally, the capillary  11  is exchanged for a new one. In the case in which pressure abnormality or a reduction in sensitivity occurs, analysis is temporarily stopped, and liquid delivery, air supply, current carrying, and the like are stopped (at this time, generally, the vacuum pumps  20 ,  21 , and  22  are not stopped). After that, when the pressures of the pumps  38  and  39  and the temperature of the ion source  2  sufficiently drop to achieve a state in which the capillary  11  can be exchanged, the exchanging flow in  FIG.  2    is carried out. After the exchanging flow is finished, liquid delivery, air supply, current carrying, and the like are started. When the pressures of the pumps  38  and  39  and the temperature of the ion source  2  are sufficiently stabilized to achieve a state in which analysis can be performed, analysis is started. 
       FIG.  5    is examples of functions that determines an exchangeable state or an analyzable state. For example, a pressure gage  45  that monitors the pressure of the LC  37  and a temperature adjusting unit  46  that monitors the temperature of the ion source  2  may be provided. In addition to these, various interlock functions may be disposed on the power supplies, analyzer covers (not shown), and the like. 
       FIG.  6    is an exemplary configuration for a preparatory experiment used for confirming differences in current values due to the position of the downstream end  12  of the capillary  11 . For convenience, differences from  FIG.  1    alone will be described. The present configuration has a drive unit  47  that changes a relative position (Z neb ) in the Z-direction of the downstream end  29  of the gas spray pipe  28  to the center of the hole  27  of the counter electrode  26  and a drive unit  48  that changes a relative position (Z capi ) of the downstream end  12  of the capillary  11  in the Z-direction. Since the relative positions of the capillary  11  and the gas spray pipe  28  in the Z-direction are changed, the sealing material  31  is formed under shaft seal scheme in the present configuration. The counter electrode  26  was used whose diameter of the hole  27  of the counter electrode  26  was 4 mm. 
     In  FIG.  6   , the downstream end  12  of the capillary  11  projects to the space in the ion source chamber  6 . The projection amount of the capillary  11  can be defined as the length of a part of the capillary  11 , which is not covered with the gas spray pipe  28  (the part of a length L), exposed to the space in the ion source chamber  6 , or can be defined as the length of the capillary  11  itself projecting from the inner wall of the ion source chamber  6 . In any case of using those definitions, it is determined whether the projection amount is proper, and thus it can be determined whether the position of the downstream end  12  of the capillary  11  is proper. The result that verifies this will be described with reference to  FIGS.  7  to  9   . 
       FIG.  7    shows results in which the value of the current carried through the counter electrode  26  is monitored by the ammeter  34  when Z neb  is fixed and the projection amount (L) of the capillary  11  is changed. Here, a distance (X) between the counter electrode  26  and the center of the capillary  11  was set to 5 mm, and a voltage of 5 kV is applied from the power supply  33  to the capillary  11  and to the gas spray pipe  28 . In  FIG.  7   , current values were plotted in which Z neb  was fixed at one millimeter intervals ranging from five to fifteen millimeters and the projection amount (L) of the capillary  11  was changed. Fixing Z neb  is based on assuming a configuration in which the position of the gas spray pipe  28  is regulated by the housing part such as the ion source chamber  6  as in  FIG.  1   . By fixing Z neb  and changing L, (1) the length of a part of the capillary  11 , which is not covered with the gas spray pipe  28  (the part of the length L), exposed to the space in the ion source chamber  6  is changed, and (2) the length of the capillary  11  itself projecting from the inner wall of the ion source chamber  6  is changed. In other words, the projection amount of the capillary  11  projecting to the space in the ion source chamber  6  is changed. 
     Under any condition for Z neb , the difference in the current value due to L is noticeable. This suggests that it can be determined whether the position of the downstream end  12  of the capillary  11  is at the normal position according to the current value. Therefore, with the use of the length L of a part of the capillary  11 , which is not covered with the gas spray pipe  28  (the part of the length L), exposed to the space in the ion source chamber  6 , or with the use of the length of the capillary  11  itself projecting from the inner wall of the ion source chamber  6 , it can be determined whether the position of the downstream end  12  is at the normal position. 
     In  FIG.  8   , current values were plotted in which Z capi  is fixed at one millimeter intervals ranging from five to twelve millimeters and the projection amount (L) of the capillary  11  is changed. Unlike  FIG.  1   , fixing Z capi  is based on assuming a configuration in which the position of the capillary  11  is regulated by the housing part such as the ion source chamber  6 . By fixing Z capi  and changing L, the length of a part of the capillary  11 , which is not covered with the gas spray pipe  28  (the part of the length L), exposed to the space in the ion source chamber  6  is changed. In other words, the projection amount of the capillary  11  projecting to the space in the ion source chamber  6  is changed. 
     Under any condition for Z capi , the difference in the current value due to L is noticeable. This suggests that it can be determined whether the position of the downstream end  12  of the capillary  11  is at the normal position according to the current value. Therefore, with the use of the length L of a part of the capillary  11 , which is not covered with the gas spray pipe  28  (the part of the length L), exposed to the space in the ion source chamber  6 , it can be determined whether the position of the downstream end  12  is at the normal position. 
       FIG.  9    shows results in which current values are plotted for every condition under which L is constant and Z capi  is changed. By fixing L and changing Z capi , the length of the capillary  11  itself projecting from the inner wall of the ion source chamber  6  is changed. In other words, the projection amount of the capillary  11  projecting to the space in the ion source chamber  6  is changed. According to the results shown in  FIG.  9   , with the use of the length of the capillary  11  itself projecting from the inner wall of the ion source chamber  6 , it can be determined whether the position of the downstream end  12  is at the normal position. 
     According to the verified results in  FIGS.  7  to  9   , it is shown that regardless that the relative position (X) between the downstream end  12  of the capillary  11  and the counter electrode  26  is constant, the projection amount of the capillary  11  projecting to the space in the ion source chamber  6  greatly depends on the current value. Accordingly, it is possible to determine whether the position of the capillary  11  is proper using the current value. 
     First Embodiment: Conclusion 
     In the ion source  2  according to the first embodiment, when no sample is supplied to the capillary  11 , the electric current carried by applying a voltage to the capillary  11  by the power supply  33  is measured by the ammeter  34 , and the controller  10  determines whether the capillary  11  is at the normal position according to measured results. Therefore, before the point in time at which the mass spectrometer  1  starts analysis of ions, it can be confirmed whether the capillary is at the normal position, and thus it is possible to prevent a trouble due to contamination, device failure, and the like, and it is possible to ensure high analysis stability. 
     Second Embodiment 
       FIG.  10    is a configuration diagram of an ion source  2  according to a second embodiment of the present invention. In the second embodiment, a configuration will be described in which the position of a capillary  11  is adjusted from the measured result of an electric current. For convenience of the description, differences from the first embodiment will be mainly described. 
     An ion source  2  of  FIG.  10    includes a drive unit  48  that adjusts the position of the capillary  11  in the Z-direction with respect to a gas spray pipe  28 . Since relative positions in the Z-direction between the capillary  11  and the gas spray pipe  28  are changed, a sealing material  31  is formed under shaft seal scheme in the present configuration. 
       FIG.  11    is a flowchart that describes procedures of exchanging the capillary  11  in the second embodiment. After a new capillary  11  is set at the time of exchanging the capillary  11 , a value of a current carried through a counter electrode  26  is monitored by an ammeter  34 . A controller  10  determines whether the position of a downstream end  12  of the capillary  11  is at the normal position according to measured results. When the downstream end  12  is at the normal position, analysis is executed. In the case in which it is not possible to determine that the downstream end  12  is at the normal position, if the number of times (n) of measuring the electric current is the first time, the drive unit  48  adjusts the position of the downstream end  12  of the capillary  11  in the Z-direction. In adjusting the position, the present position may be determined from the current value of the measured result based on the results obtained beforehand in  FIG.  7   , for example, and the difference between the position and the normal position may be corrected. This adjustment may be automatic or manual. After the position is adjusted, the electric current is again measured. When the measured result is in the range of I 1 ≤I≤I 2  similarly to  FIG.  2   , the result is accepted, and analysis is started. In the case in which the measured result is not accepted even after measurement is again performed, the number of times n=2, and then it is determined that an error is due to the component itself. An action can be taken, such as outputting an alert similarly to  FIG.  2   , or exchanging the capillary  11  to a new capillary  11 , for example. The threshold of the number of times of measurement, n, can be set to a value other than n=2. 
     In accordance with the ion source  2  according to the second embodiment, even though the position at which the capillary  11  is installed is not optimum, it is possible to adjust the position without removing the capillary  11 . Accordingly, it is possible to minimize the loss of throughput due to exchanging the capillary  11 . 
     Third Embodiment 
       FIG.  12    is a configuration diagram of an ion source  2  according to a third embodiment of the present invention. In the third embodiment, a configuration will be described in which the position of a gas spray pipe  28  is adjusted from the measured result of an electric current. For convenience of the description, differences from the first embodiment will be mainly described. 
     The ion source  2  of  FIG.  12    includes a drive unit  47  that adjusts the position of a gas spray pipe  28  in the Z-direction with respect to a capillary  11 . Since relative positions in the Z-direction between the capillary  11  and the gas spray pipe  28  are changed, the sealing material  31  is formed under shaft seal scheme in the present configuration. Since the position of the capillary  11  is a reference position, the structure is provided such that the position of the capillary  11  or of a connector  30  is regulated with respect to a housing part such as an ion source chamber  6  through some member (not shown) and the like. The procedures of exchanging the capillary  11  is almost similar to  FIG.  11   , and the description thereof is omitted. 
     Similarly to the second embodiment, in the ion source  2  according to the third embodiment, even though the position at which the capillary  11  is installed is not optimum, it is possible to adjust the position without removing the capillary  11 . Accordingly, it is possible to minimize the loss of throughput due to exchanging the capillary  11 . The drive unit  47  described in the second embodiment and the drive unit  48  described in the third embodiment can be combined for use as in  FIG.  6   . 
     Fourth Embodiment 
       FIG.  13    is a configuration diagram of an ion source  2  according to a fourth embodiment of the present invention. In the fourth embodiment, an ion source with a configuration in which the position of the downstream end of the capillary  11  is determined from the current value of a leading-in electrode  7  will be described. For convenience of the description, differences from the first embodiment will be mainly described. 
     Unlike the first to the third embodiments, in  FIG.  13   , the counter electrode  26  is not present. Under the conditions in which the flow rate of a sample liquid solution is small, in some cases, spraying a gas from a counter electrode  26  or from the inner side of the counter electrode  26  is unnecessary. The present configuration is applicable in such a case. Since no counter electrode  26  is provided in the present configuration, an ammeter  34  measures the value of a current carried through the leading-in electrode  7 . The other configurations and procedures are similar to the first to the third embodiments, and the similar effect can be obtained. 
     Fifth Embodiment 
       FIG.  14    is a configuration diagram of an ion source  2  according to a fifth embodiment of the present invention. The ion source  2  according to the fifth embodiment includes no gas spray pipe  28 . For convenience of the description, differences from the first embodiment will be mainly described. 
     Under the conditions in which the flow rate of a sample liquid solution is small, in some cases, spraying a gas from a gas spray pipe  28  or from the inner side of the gas spray pipe  28  is unnecessary. Since no gas spray pipe  28  is provided, a capillary  11  or a connector  30  is installed on an adapter member  49  and the like in the fifth embodiment. The other configurations and procedures are similar to the first to the fourth embodiments, and the similar effect can be obtained. 
     Sixth Embodiment 
       FIG.  15    is a configuration diagram of an ion source  2  according to a sixth embodiment of the present invention. In the sixth embodiment, a configuration will be described in which the position of the downstream end of a capillary  11  is determined from the current value of a deflection electrode. For convenience of the description, differences from the first embodiment will be mainly described. 
     In addition to the configuration described in the first embodiment, the configuration of  FIG.  15    includes a deflection electrode  50 . When noise components such as droplets flow from a leading-in electrode  7 , these lead to contamination of various electrodes in the inside of s vacuum chamber  4 , causing a reduction in sensitivity. Furthermore, these also lead to shortening the lifetime of a detector  25 . It is possible to prevent the inflow of noise to some extent by spraying a gas in the reverse orientation from the inside of a counter electrode  26 . However, in the case in which this prevention is not enough, for example, an action has to be necessary such as putting away the downstream end  12  of the capillary  11 , which is a spray port of ions or droplets. Although the inflow of noise is reduced by putting away the downstream end  12 , the inflow of ions is also reduced, leading to a reduction in sensitivity. In order to compensate this reduction in sensitivity, in some cases, a deflection electrode  50  is disposed in an ion source chamber  6 . By applying a voltage a few positive or negative kV at the maximum to the deflection electrode  50 , ions are forcedly deflected to the direction of the leading-in electrode  7 , and the efficiency of introducing ions is improved. 
     In the case in which after the capillary  11  is located away from the leading-in electrode  7  and then the current value of the counter electrode  26  or of the leading-in electrode  7  is measured, it is likely that the electric current is detected unsuccessfully because the distance between the capillary  11  and the leading-in electrode  7  is large. In this case, by monitoring the value of a current carried through a deflection electrode  50  that can be disposed much closer, the effect similar to measuring the current value of the counter electrode  26  or the leading-in electrode  7  can be obtained. The other configurations and procedures are similar to the first to the fifth embodiments. 
     Seventh Embodiment 
       FIG.  16    is a configuration diagram of an ion source  2  according to a seventh embodiment of the present invention. In the seventh embodiment, a configuration will be described in which the position of the downstream end of a capillary  11  is determined from the current value of an electric current measurement dedicated electrode. For convenience of the description, differences from the first embodiment will be mainly described. 
     In addition to the configuration described in the first embodiment, the configuration of  FIG.  16    includes an electric current measurement dedicated electrode  51 . Since contamination substances such as droplets together with ions are also sprayed from a downstream end  12  of the capillary  11 , it is likely that the surfaces of a counter electrode  26 , a leading-in electrode  7 , a deflection electrode  50 , and the like are contaminated. Since a mass spectrometer  1  draws ions from a hole  8  of the leading-in electrode  7  by vacuum, ions are introduced by the force of an air current and the rate of a reduction in sensitivity is small, even though these electrodes are contaminated more or less. However, in the case in which the electric currents of these electrodes are measured, there is concern that the electric field is changed due to contamination. Therefore, in the seventh embodiment, the electric current measurement dedicated electrode  51  exclusively used for monitoring the electric current is disposed. If the electric current measurement dedicated electrode  51  is not located at a position closer to the downstream end  12  of the capillary  11  than the other electrodes, a discharge current is carried through the other electrodes. On the other hand, if the electric current measurement dedicated electrode  51  is located too close to the downstream end  12 , this disturbs the electric field, causing a reduction in ionization efficiency. As a result, desirably, a drive unit  52  is disposed as in  FIG.  16   , which allows the electric current measurement dedicated electrode  51  to move at a place where the electric current measurement dedicated electrode  51  is not an obstacle against the electric field at the time of analysis and is not exposed to contamination. 
     In accordance with the ion source  2  according to the seventh embodiment, since the reliability of the result measured by an ammeter due to contamination can be enhanced, the determination accuracy whether the downstream end  12  is at the normal position is also improved. Furthermore, it is also possible to mitigate the influence on the analysis of the electric current measurement dedicated electrode  51 . 
     Eighth Embodiment 
       FIG.  17    is a flowchart that describes capillary exchanging procedures according to an eighth embodiment. In the eighth embodiment, an example operation will be described in which the voltage of a capillary is adjusted based on the measured result of an electric current to carry out a process of analysis. The configurations of an ion source  2  and a mass spectrometer  1  are similar to the first to the seventh embodiments. In the following, for convenience of explanation, the configuration of the ion source  2  according to the first embodiment is assumed, and the present flowchart can be used for the ion sources  2  according to the other embodiments. 
     After a new capillary  11  is set at the time of exchanging a capillary  11 , a value of a current carried through a counter electrode  26  is monitored by an ammeter  34 . Similarly to  FIG.  2    when the measured result is in the range of I 1 ≤I≤I 2 , the result is accepted, and analysis is started. Even in the case in which the result is not accepted, as long as the result is in a range (I 3 ≤I≤I 4 ) in which a similar electric field (sensitivity) is obtained by adjusting the value of a voltage applied to the capillary  11 , the voltage is adjusted without adjusting the position or again exchanging the capillary  11  to again measure the current value. If the electric current is again measured and then the result is acceptable, analysis is started under the conditions under which the voltage is corrected. In a case of ranges where the voltage cannot be adjusted (other than I 3 ≤I≤I 4 ) or in a case of non-acceptable result even by re-measuring the electric current, it is determined that an error is due to the component itself. Then an action can be taken such as outputting an alert or exchanging the capillary  11  to a new capillary  11 , for example. The acceptable conditions of I 1 ≤I≤I 2  and I 3 ≤I≤I 4  are examples, the range of acceptance may be set to a broader range or a narrower range using different conditional expressions. 
       FIG.  18    is a graph that describes a range of I 3 ≤I≤I 4 .  FIG.  18    plots results in which in the configuration of  FIG.  6   , X is fixed to 3 mm, Z neb  is fixed to 25 mm, and L and the voltage value are changed. The capillary  11  having an outer diameter of 0.27 mm, and a gas spray pipe  28  having a tip end inner diameter of 0.4 mm were used. The optimum conditions with this configuration are assumed that the applied voltage to the capillary  11  is 5.5 kV, and L=0.7 mm (about 30 μA). Since a power supply  33  used in experiment has an application range of 5.8 kV at the maximum, the range in which 30 μA can be achieved under conditions of increment of L=0.1 mm is the range of L=0.6 to 0.9 mm. In other words, in the configuration of L, it is considered that 30 μA can be achieved by adjusting the voltage. For example, when a result that 40 μA is obtained at an applied voltage of 5.5 kV at the first electric current measurement, it can be assumed that L=about 0.9 mm. In this case, by dropping the voltage to 5.3 kV, the electric field through which an electric current of about 30 μA is carried can be adjusted. 
     The corrected applied voltage at the time of analysis will be described assuming a case in which the optimum voltage is 4 kV in actual analysis. In the case in which the correlation between the horizontal axis and the vertical axis in  FIG.  18    shows a tendency similar to the correlation between the applied voltage and the ionic strength at the time of analysis, in the example described above, the voltage is adjusted from 5.5 kV to 5.3 kV. Therefore, the corrected voltage at the time of analysis is set to 3.855 kV according to the ratio of voltages, and the ionic strength equivalent to the conditions of L=0.7 mm and a voltage of 4 kV can be obtained. Since the conversion formula relating to the correction also depends on the other analysis conditions and the like, the example is non-limiting. 
     Using the capillary exchange procedures according to the eighth embodiment, even though the position at which the capillary  11  is installed is not optimum, it is possible to adjust the position without removing the capillary  11 , and thus it is possible to minimize the loss of throughput due to exchange. The method of adjusting a voltage in the eighth embodiment may be combined with the method of adjusting the position of the downstream end  12  in the other embodiments. 
     Ninth Embodiment 
       FIG.  19    is a flowchart that describes capillary exchanging procedures according to a ninth embodiment of the present invention. In the ninth embodiment, the profiles of current values obtained by applying a plurality of voltages is applied to a capillary  11  are compared with a reference profile, and it is determined whether the position of a downstream end  12  is acceptable. The configurations of an ion source  2  and a mass spectrometer  1  are similar to the first to the eighth embodiments. 
       FIGS.  20  to  22    show an example of comparing the reference profile with measured results. When different voltages are applied to the capillary  11 , profiles plotted by a solid line in  FIGS.  20  to  22    are obtained. A controller  10  uses these solid lines as the reference profile. In  FIG.  20   , the threshold of the voltage value at which electric current measurement is feasible (a threshold voltage at which the current value rises) is varied between the reference profile and actually measured results. In  FIG.  21   , the slope of the current value with respect to the applied voltage is varied between the reference profile and actually measured results. In  FIG.  22   , the current value with respect to the same applied voltage is varied between the reference profile and actually measured results. The controller  10  sets a tolerance to errors between the reference profile and the actually measured results, and determines that the result within the tolerance is accepted, whereas determines that the result out of the tolerance is not accepted. For the determination, an indicator other than this may be used. 
     In accordance with the procedures according to the ninth embodiment, in comparison with the case in which one voltage is applied to the capillary  11 , determination based on the current value is made more accurate. The method of comparing the reference profile with the actually measured results according to the ninth embodiment can be applied to the capillary exchanging flow in  FIG.  11    or  FIG.  17   . 
     Tenth Embodiment 
       FIG.  23    is a flowchart that describes operation procedures of an ion source according to a tenth embodiment of the present invention. An ion source  2  according to the tenth embodiment measures a current value at the time of posing analysis. When determining whether the result of measuring the current value is acceptable, the methods of the foregoing embodiments can be used. In the case in which the result is accepted, the process goes to the subsequent analysis, whereas in the case in which the result is not accepted, exchanging a capillary  11 , adjusting the position, or adjusting the voltage is carried out. The methods of the foregoing embodiments may be combined. 
       FIG.  24    is an example result in which current values are repeatedly measured. When current values are repeatedly measured, an analysis count-to-error curve as shown in  FIG.  24    is obtained. As the error on the vertical axis, various errors shown in  FIGS.  20  to  22    can be used, for example. A controller  10  can determine that the result is not accepted at the point in time at which the integrated value of errors reaches the threshold or more. Thus, it is possible to diagnose degradation of components or the signs of lifetime. 
     Exemplary Modifications of Present Invention 
     The present invention is not limited to the foregoing embodiment, and includes various exemplary modifications. For example, the foregoing embodiments are described for easily understanding the present invention, and are not necessarily limited to ones including all the described configurations. Moreover, a part of the configuration of an embodiment may be replaced with the configuration of another embodiment. Furthermore, to the configuration of an embodiment, the configuration of another embodiment may be added. In addition, in regard to a part of the configurations of the embodiments, another configuration may be added, removed, and replaced. Moreover, since a voltage is applied to various electrodes used in the embodiments, the electrodes are sometimes installed through an insulating member at the time of installation to the housing part and the like. Therefore, it should be noted that no insulator is shown in the drawings for convenience. 
     In the embodiments described above, the description is made in which when the power supply  9  applies a voltage to the capillary  11 , the electric current carried through the electrodes is measured by the ammeter  34 . However, the ammeter  34  may directly or indirectly measure the electric current carried through the capillary  11 . Even in this case, it is possible to exert effects similar the embodiments. In other words, it is sufficient that when no sample is supplied to the capillary  11 , the electric current produced by applying a voltage to the capillary  11  by the power supply  9  is measured. 
     In the embodiments described above, the controller  10  can output the projection amount information in any format. For example, the projection amount can be presented to the user through a display and the like. Alternatively, for example, data describing the projection amount may be output to another arithmetic logic unit and the like. In addition to these, an appropriate output format can be used. 
     In the embodiments described above, the controller  10  may be configured using hardware such as a circuit device implementing the functions of the controller  10 , for example, or the controller  10  may be configured by software implementing functions of the controller  10  being executed by an arithmetic logic unit such as a CPU (Central Processing Unit). 
     REFERENCE SIGNS LIST 
     
         
           1 : mass spectrometer 
           2 : ion source 
           3 : mass spectrometric analyzer 
           4 : vacuum chamber 
           5 : ion producer 
           6 : ion source chamber 
           7 : leading-in electrode 
           8 : hole 
           9 : power supply 
           10 : controller 
           11 : capillary 
           12 : downstream end 
           13 : air outlet port 
           14 : window 
           15  to  17 : vacuum chamber 
           18  to  19 : hole 
           20  to  22 : vacuum pump 
           23 : ion transport unit 
           24 : ion analyzer 
           25 : detector 
           26 : counter electrode 
           27 : hole 
           28 : gas spray pipe 
           29 : downstream end 
           30 : connector 
           31 : sealing material 
           32 : pipe connecting unit 
           33 : power supply 
           34 : ammeter 
           35 : indicator 
           37 : liquid chromatograph (LC) 
           38  to  39 : pump 
           40 : mixer 
           41 : sample injection unit 
           42 : separation column 
           43  to  44 : moving phase 
           45 : pressure gage 
           46 : temperature adjusting unit 
           47 : drive unit 
           48 : drive unit 
           49 : adapter member 
           50 : deflection electrode 
           51 : electric current measurement dedicated electrode 
           52 : drive unit