JP3535117B2 - Ion trap mass spectrometer - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ion trap mass spectrometer, and more particularly to an ion trap mass spectrometer called a three-dimensional quadrupole mass spectrometer.

[0002]

2. Description of the Related Art In recent years, interest in detecting and analyzing environmental pollutants has increased, and one type of analyzer that can respond to this is an ion trap mass spectrometer, which is separated by a separating means. Introduce the sample into the ion trap,
It is ionized by an ionization means in the inside, mass-dispersed, and the obtained mass spectrum is analyzed, which is very effective in the analysis and measurement of various trace components.

A typical example of a mass spectrometer using this ion trap is a 3DQMS (three-dimensional quadrupole mass spectrometer).
As shown in FIG. 5, this includes one ring electrode 3 and two pairs of end cap electrodes 1 and 2 with the ring electrode 3 sandwiched therebetween, for a total of three electrodes. An ion trap space (a space for confining ions) is created, and the ionized sample is confined in this ion trap space.

Then, by applying a predetermined voltage to each of the electrodes 1 to 3 constituting the 3DQMS as shown in the figure, only the ions having a specific mass number are confined in the ion trap space. That is, a so-called ion trap function is obtained, and as a result, a function as a mass spectrometer can be obtained.

By the way, in such an ion trap mass spectrometer, if the sample trapped in the ion trap space is deposited on each of the electrodes 1 to 3, the analysis accuracy will be deteriorated. Therefore, in order to suppress precipitation of this sample, each electrode 1 to 3 is heated during measurement and analysis so that they are kept at a predetermined temperature, for example, a predetermined temperature in the range of 100 ° C to 350 ° C.

Therefore, for this reason, for example, Japanese Patent Laid-Open No. 10-5
In Japanese Patent No. 5777 and Japanese Patent Laid-Open No. 10-294078,
It discloses a method of heating the end cap electrode and the ring electrode by using a heating means such as a heater.

[0007]

It cannot be said that the above-mentioned prior art takes into consideration the fact that the end cap electrodes and the ring electrodes constituting the ion trap mass spectrometric means are kept at a uniform temperature, and the analytical precision is maintained. I had a problem with.
That is, in the conventional technique, since each electrode is heated by a different heater, a temperature difference occurs between the electrodes, and it is difficult to maintain a uniform temperature.

Here, if the temperature of each electrode is not uniform and is not accurately stabilized at the set temperature as described above, the separated sample is recombined in the low temperature part and the sample is thermally decomposed in the high temperature part. There is a problem before ionization, such as causing. As a result, in the conventional technique, there is a possibility that the analysis accuracy may be deteriorated and the role of the separation analysis device may not be fulfilled.

An object of the present invention is to provide an ion trap mass spectrometer in which the temperatures of the end cap electrode and the ring electrode forming the ion trap space can be made sufficiently uniform.

[0010]

The above object is to provide an ion trap mass spectrometer of a type in which an ion trap space is formed by two end cap electrodes and one ring electrode, and a heating block having a substantially cylindrical shape, This is achieved by providing at least one heater attached to this heating block and accommodating the two end cap electrodes and one ring electrode in the heating block.

At this time, a temperature sensor may be installed on the end cap electrode and the ring electrode, and the supply of electric power to the heater may be controlled based on the temperature detection result by the temperature sensor. A heat insulating cover may be provided outside the individual end cap electrodes.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The ion trap mass spectrometer according to the present invention will be described in detail below with reference to the embodiments shown in the drawings. 1 and 2 show an embodiment of the present invention, in which FIG. 1 is a sectional view of an ion trap mass spectrometer according to the present invention, and FIG. 2 is a top view of FIG. FIG. 1 is, therefore, FIG.
It is a cross-sectional view taken along the line.

In these figures, 4 is a heating block, 5 is a heater, 6 is a heat insulating cover, and 7 is a temperature sensor. Therefore, also in the ion trap mass spectrometer according to this embodiment, an ion trap space is provided. End cap electrodes 1 and 2 and ring electrode 3 for forming
Is the same as the case of the conventional technique described in FIG. 4, but here the ion trap space is represented by TS.

First, the heating block 4 is a substantially cylindrical member made of a material having a relatively high thermal conductivity while being electrically insulating and capable of withstanding high temperatures, for example, a substantially cylindrical member. Four heater accommodating portions 4A, which are also substantially cylindrical in shape, are arranged on the outer peripheral portion at substantially equal intervals in this embodiment.

As is apparent from FIG. 1, the heating block 4 is provided with a groove portion 4B in a ring shape at a substantially central portion in the lengthwise direction of its substantially cylindrical main body. The heater accommodating portion 4A has a vertically divided shape in the figure. Then, these heater housing portions 4A
Each of the heaters 5 has a total of eight heaters 5 mounted therein.

Here, these heaters 4 are constituted by electric heaters such as heating wire heaters and ceramic heaters, and when they are supplied with electric power, they generate heat and serve to raise the temperature of the heating block 5. The heat insulating cover 6 is a substantially disc-shaped member made of a heat insulating material such as an inorganic fiber material, and is inserted into the heating block 4 so as to cover the outer surface side of the end cap electrodes 1 and 2, and these electrodes are formed. It keeps the heat from the body to be kept warm.

The temperature sensor 7 detects the temperature of each electrode, that is, the end cap electrodes 1 and 2 and the ring electrode 3, and generates a temperature detection signal. Therefore, for example, a thermistor (trade name) ) Or the like, which is provided in each of the electrodes, for example, in a buried form, as shown in the drawing.

Next, FIG. 3 is a diagram showing a control system of each heater 5 in this embodiment, which is composed of a heater power source 11, a temperature control device 12, and a data processing device 13, and each heater 5 has: Power is supplied from the heater power supply 11. The heater power supply 11 is controlled by the temperature control device 12, and controls the current to be supplied to the heater 5 so as to obtain the predetermined temperature set value instructed by the data processing device 13.

Therefore, the temperature control device 12 is
The temperature of each of the end cap electrodes 1 and 2 and the ring electrode 3 forming the ion trap space TS is individually input from each temperature sensor 7, and these are compared with a temperature set value instructed by the data processing device 13. Then, the heater power supply 11
From the above, the electric power (current) supplied to each heater 5 is determined so that the temperature of each heater 5 is individually controlled.

As a result, the temperature of the end cap electrodes 1 and 2 and the ring electrode 3 is controlled so as to converge to the temperature set value supplied from the data processing device 13 to the temperature control device 12. At this time, heat from each heater 5 is supplied to each electrode after heating the heating block 5.

Here, the heating block 5 is heated by the heater 5 in a range from a low temperature range of about 100 ° C. to a high temperature range of about 350 ° C. according to a temperature set value instructed by the data processing device 13. However, at this time, since the heating block 5 is rich in thermal conductivity, first, the heating block 5
After the whole is uniformly heated and brought to a uniform temperature, the end cap electrodes 1 and 2 and the ring electrode 3 housed inside the heating block 5 are heated, so that they are also accurately heated to a uniform temperature. Will be done.

At this time, these electrodes, that is, the end cap electrodes 1 and 2 and the ring electrode 3 are usually made of a metal having a high heat transfer property such as copper or a copper alloy.
Moreover, at this time, in this embodiment, a temperature sensor is provided for each electrode, and the plurality of heaters 5 are individually controlled according to the detection results, so that the temperature is controlled to a uniform temperature with extremely high accuracy. be able to.

Here, the analysis operation according to this embodiment will be described with reference to FIG. 3. First, the sample is separated into each component by the gas chromatograph 8 and then supplied to the ion trap mass spectrometer together with the carrier gas to obtain the ions. It is introduced into the trap space TS.

At this time, in the ion trap space TS,
The end cap electrodes 1 and 2 and the ring electrode 3 are kept at a high vacuum in advance, and are kept at a predetermined temperature by the heater 5 according to the sample to be analyzed. The sample in the ion trap space TS is ionized by the generated electron beam and accumulated for a certain period of time, and then mass dispersion is performed.

The ions thus mass-dispersed in the ion trap space TS are detected by the detector 10, and the detected signal is processed by the data processor 13 to obtain a mass spectrum and obtain an analysis result. But,
At this time, in this embodiment, since the heating block 5 is provided, the temperature of each electrode, that is, the end cap electrodes 1 and 2 and the ring electrode 3 is uniform to the set temperature instructed by the data processing device 13. It is held with high precision.

Therefore, according to this embodiment, the components separated by the gas chromatograph 8 can be efficiently ionized without impairing the separation. As a result,
It is possible to easily obtain a mass spectrum that sufficiently matches the standard data for data retrieval.

As a result, the recombination of the sample ions due to the variation in the electrode temperature and the spectrum change due to the chemical ionization reaction do not occur, which can greatly contribute to the improvement of the analysis accuracy.

Here, FIG. 4 is an example comparing the analysis result according to one embodiment of the present invention with the case of the prior art, and shows the peak in the case of the prior art without the heating block shown in FIG. 4 (a). It can be seen that the peak 2 in the case of the embodiment of the present invention shown in FIG.

From FIG. 4, according to the embodiment of the present invention, even when the sample is a high boiling point compound, there is no reduction in separation due to adsorption or the like, and a peak with high separation ability can be easily obtained. It can be seen that the accuracy of analytical characteristics can be greatly improved.

[0030]

According to the present invention, each electrode of the ion trap mass spectrometer can be heated accurately and uniformly,
This has the effect of significantly improving the analysis accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an ion trap mass spectrometer according to an embodiment of the present invention.

FIG. 2 is a top view showing an embodiment of the ion trap mass spectrometer according to the embodiment of the present invention.

FIG. 3 is a block diagram of temperature control according to an embodiment of the present invention.

FIG. 4 is a characteristic diagram showing characteristics according to an embodiment of the present invention in comparison with a case of a conventional technique.

FIG. 5 is an explanatory diagram showing an example of an ion trap mass spectrometer according to a conventional technique.

[Explanation of symbols]

1, 2 End cap electrode 3 ring electrode 5 heater 4 heating block 5 heater 6 insulation cover 7 Temperature sensor 8 gas chromatograph 9 electron gun 10 detector 11 Heater power supply 12 Temperature control device 13 Data processing equipment

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kohei Mochizuki 882 Ichige, Ichige, Hitachinaka City, Ibaraki Prefecture, Hitachi Science Systems Co., Ltd. (56) Reference JP 10-12187 (JP, A) JP 10- 294078 (JP, A) JP 11-86780 (JP, A) JP 59-134546 (JP, A) JP 10-55777 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 49/00-49/42 H01J 37/147 H01J 37/16

Claims (3)

(57) [Claims] 1. An ion trap mass spectrometer of the type in which an ion trap space is formed by two end cap electrodes and one ring electrode, and a substantially cylindrical heating block and at least one heating block attached to this heating block. An ion trap mass spectrometer characterized in that a plurality of heaters are provided, and the two end cap electrodes and one ring electrode are housed in the heating block. 2. The invention according to claim 1, wherein a temperature sensor is installed on the end cap electrode and the ring electrode, and supply of electric power to the heater is controlled based on a temperature detection result of the temperature sensor. An ion trap mass spectrometer characterized by being configured as follows. 3. The ion trap mass spectrometer according to claim 1, wherein a heat insulating cover is provided outside the two end cap electrodes.