JP2007324008A - Electro-spray ion source and mass spectrometer equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-spray ion source which ionizes a sample by emitting the sample from a nozzle by impressing voltage and a mass spectrometer, in which the voltage impressed is automatically adjusted to a specified value so that a liquid drop is not generated at the nozzle tip. <P>SOLUTION: The mass spectrometer comprises a CCD camera with light receiving sensor which monitors the tip of an ESI chip and sends a signal to an air spray device when a liquid drop with an established radius or more is generated at the tip of the ESI chip, the air spray device which blows out the liquid drop by automatically spraying air when it receives a signal from the CCD camera with light receiving sensor. When the air spray device blows out the liquid drop, a signal is received and the voltage is automatically increased for an established portion and voltage increase is repeated until the liquid drop is no more generated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrospray ion source applied to a mass spectrometer and a mass spectrometer equipped with the electrospray ion source, and more particularly, to an electrospray ion source that can be easily set up for an apparatus and a mass spectrometer equipped with the electrospray ion source.

  One conventional technique for measuring a liquid sample with a mass spectrometer is a liquid chromatograph (LC) 1 as shown in FIG. 1, an autosampler 2 for injecting a liquid sample, a column 3, and an electrospray interface. There is a system (LC-ESI-MS) composed of (hereinafter referred to as ESI) chip and mass spectrometer 5. As shown in the figure, the liquid chromatograph (LC) 1 is composed of two kinds of solvents (b, c) and a pump a that sends them out, and the mass spectrometer 5 is composed of an ion source d, an analyzer e, and a detector f. In this system, when the solvent or liquid sample reaches the ion source d of the mass spectrometer 5, it is vaporized by a high temperature of 200 to 300 ° C. and an applied voltage of 1 to 4 kV to be in an ionized state. In this example, the mass spectrometer measures the mass number per monovalent ion (m / z). In LC-ESI-MS or LC-ESI-MS / MS, before measuring a sample, first, conditions for stable ionization in a state in which only a solvent is passed, particularly a voltage value, are set. At this time, when the voltage is appropriate, the solvent evaporates and enters the ion source d of the mass spectrometer 5. However, when the voltage is low, the solvent cannot be sufficiently evaporated and remains in solution, so It becomes a liquid ball and accumulates. If the liquid enters the ion source d of the mass spectrometer 5 in a liquid state, if the contaminant is mixed in the liquid, the ion source d may be contaminated and a cleaning operation may be required.

  A technique for facilitating this cleaning operation is described in Patent Document 1.

  In order to avoid such cleaning work, until ionization stabilizes, the operator always performs the work of monitoring the tip of the chip and blowing the liquid ball by air blowing to raise the voltage little by little when the liquid ball is made. Is common.

JP 2005-259477 A

  In the above-described work for stabilizing ionization, if a liquid ball is formed by monitoring the tip of the chip, the liquid ball must be blown off by air blowing and monitored by a person until the voltage becomes appropriate. For this reason, it took time to set voltage conditions for stable ionization. The objective of this invention is providing the mass spectrometer provided with the mechanism in which the stabilization operation | work of ionization is possible without requiring a manual labor.

  The configuration of the present invention for achieving the above object is as follows.

  A monitoring means for optically monitoring the tip of the nozzle that discharges the sample of the electrospray ion source, and the monitoring means blows an airflow to the nozzle in response to detecting that a liquid ball is generated at the nozzle tip. An electrospray ion source comprising:

  The monitoring means is preferably a CCD camera from the viewpoint of cost, but any monitoring means can be used as long as it can optically monitor the nozzle tip. The tip of the nozzle (ESI chip) is monitored, and when a liquid ball larger than the radius set at the tip of the ESI chip is produced, a signal is sent to the air blowing device, and the air blowing device that receives the signal automatically blows air. Blow off the liquid ball. Subsequently, when the air blowing device blows off the liquid ball, a signal may be sent to the mass spectrometer, and the voltage may be automatically increased by a set amount and repeated until the liquid ball is no longer formed. It is also preferable to have a function of notifying abnormality by an alarm when the voltage of the mass spectrometer is excessively increased.

  According to the present invention, it is possible to automatically perform voltage condition setting work for stable ionization in LC-ESI-MS.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a general configuration diagram of a mass spectrometer according to the present invention. In this example, HPLC MAGIC2002 manufactured by michrom BioResources is used as the liquid chromatograph (LC) 1, HTS-Pal manufactured by CTC Analytical is used as the autosampler 2, and LCQdecaXP manufactured by Thermo Electron is used as the mass spectrometer 5. Yes.

FIG. 2 shows an ESI ion source of LC-ESI-MS, and a newly installed device (air blowing device 6, CCD camera 7 with a light receiving sensor, monitor 8, light source 9 for projecting light on the tip of the ESI chip. )showed that. Arrows (1) and (2) in the figure indicate the flow of signals. (1)
When the solvent at the tip of the ESI chip becomes liquid droplets, the light from the light source is reflected or absorbed by the liquid balls, sensed by the CCD camera 7 with a light receiving sensor, and an image is displayed on the monitor 8. The monitor 8 aligns the 0 point with respect to the ESI tip end, and monitors the radius of the droplet formed on the ESI tip from the 0 point. The CCD camera 7 with a light receiving sensor sends a signal to the air blowing device 6 when the radius of the liquid ball becomes equal to or greater than the value set by the user. (2) When the air blowing device 6 receives a signal from the CCD camera 7 with the light receiving sensor, it blows air. When the air is blown, the signal is sent from the air blowing device 6 to the mass spectrometer, and the mass spectrometer has a low voltage. Judging and automatically increasing the voltage by the value set by the user.

  FIG. 3 shows the installation position of the ESI chip and the air blowing angle (viewed from the side). Since the position of the ESI chip does not directly enter the mass spectrometer when the liquid ball flies, it is better to deviate from the voltage application direction. An angle of about 20 to 40 degrees is good, and in this embodiment, the angle is set to 20 degrees. Also, the air blowing angle should not be directly in the mass spectrometer when the liquid ball flies, so it is better to deviate from the direction where the voltage is applied. As shown in FIG. Is good.

  FIG. 4 shows the ESI chip and the air blowing angle (viewed from above). In the present embodiment, the installation position of the ESI chip was set at 20 degrees, and the air blowing angle was set at 20 degrees. The reason for determining the installation angle is the same reason as described above with reference to FIG.

  FIG. 5 shows the installation positions of the CCD camera 7 with the light receiving sensor and the light source 9. Any position that does not interfere with ionization and does not hit when the liquid ball flies is acceptable. In this embodiment, as shown in FIG. 5, it is installed in a direction perpendicular to the direction in which the voltage is applied. In this embodiment, the distance from the CCD camera 7 with the light receiving sensor to the ESI chip tip and the distance from the light source 9 to the ESI chip tip are both 10 cm.

  FIG. 6 shows a flowchart of this embodiment.

  An embodiment of the present invention will be described based on the flowchart of FIG.

First, the user sets an air blowing device and a mass spectrometer. Regarding the air blowing device, when the radius r of the liquid ball exceeds the value set by the user as a reference for blowing air, it is set to 0.5 mm in this embodiment. Air was blown at 0.5 to 1.0 cm ³ / sec for 2 seconds. Next, make settings for the mass spectrometer. The minimum voltage m and the maximum voltage M at the start of the ionization stabilization work to be performed are set. If the maximum voltage is too high, the ESI chip may be damaged. Therefore, a value that damages the ESI chip when the voltage further increases is set. Further, a voltage increase value δ that increases when air is blown once and an ionization stabilization time T are set. In this embodiment, the minimum voltage m is set to 1.8 kV, the maximum voltage M is set to 4.0 kV, the voltage increase value δ is set to 0.1 kV, and the ionization stabilization time T is set to 15 minutes.

  With the CCD camera with light receiving sensor, monitor, and light source turned on, the air blowing device and mass spectrometer are started. When the voltage is initially low, a liquid ball is formed, and when the radius exceeds the reference value r, a signal is sent from the CCD camera with a light receiving sensor to the air blowing device to blow air once. This time, a signal is sent to the mass spectrometer and the voltage increases by δ. Still, when a liquid ball is formed, when the radius of the liquid ball exceeds r, a signal is sent again from the CCD camera with the light receiving sensor to the air blowing device, and air is blown once, and the signal is sent to the mass spectrometer. The voltage increases by δ. When this process is repeated, the voltage becomes appropriate and the liquid ball is no longer formed, and when the time when no signal is received by the mass spectrometer, that is, when the ionization stable time reaches T, an alarm is sent to the user informing that the ionization is stable. Be notified. Further, when the ionization stable time does not reach T, the voltage continues to rise again. If the ionization is not stabilized even when the voltage reaches the maximum voltage M, an alarm for notifying the user is notified. In this case, there may be an abnormality in a place other than the voltage setting.

  The above process is repeated until the voltage reaches an appropriate value or reaches the maximum voltage.

1 is a general configuration diagram of a mass spectrometer according to the present invention. Schematic of the ESI ion source of LC-ESI-MS and the apparatus newly installed by this invention. The figure which shows the installation position of an ESI chip | tip, and the angle (view seen from the side) which blows air. The figure which shows the angle (view seen from the top) which blows an ESI chip | tip and air. The figure which shows the installation position of CCD camera 7 with a light receiving sensor, and the light source 9. FIG. The figure which shows the flowchart of a present Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid chromatograph (LC), 2 ... Autosampler, 3 ... Column, 4 ... ESI chip, 5 ... Mass spectrometer, 6 ... Air blower, 7 ... CCD camera with a photo sensor, 8 ... Monitor, 9 ... Light source A ... pump, b ... solvent A, c ... solvent B, d ... ESI ion source, e ... analyzer, f ... detector.

Claims (5)

Monitoring means for optically monitoring the nozzle tip emitting the sample of the electrospray ion source;
An airflow blowing means for blowing an airflow to the nozzle in response to detecting that the liquid ball is generated at the tip of the nozzle;
An electrospray ion source comprising: The electrospray ion source of claim 1
The monitoring unit includes a determination unit that determines whether or not the liquid ball generated at the tip of the nozzle is equal to or larger than a preset radius, and the determination unit determines that the liquid ball is equal to or larger than the radius. An electrospray ion source comprising control means for controlling the airflow blowing means to blow an airflow based on the above. The electrospray ion source according to claim 1 or 2,
An electrospray ion source comprising voltage adjusting means for applying a preset voltage to a voltage applied to the nozzle in response to the air current blowing means blowing air current. The electrospray ion source according to claim 2 or 3,
An electrospray ion source comprising warning generating means for issuing a warning when a voltage applied to the nozzle exceeds a preset voltage.   A mass spectrometer comprising the electrospray ion source according to claim 1.

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