JPS594444Y2 - Sample supply device for ion cyclotron resonance mass spectrometer - Google Patents

Description

[Detailed description of the invention] This invention is a mass spectrometer that utilizes the phenomenon in which charged particles such as ions moving circularly in a magnetic field cause cyclotron resonance in response to an alternating electric field. The present invention relates to an apparatus for supplying a sample into a chamber in which a sample is supplied.

A general mass spectrometer detects the generated ions after passing them through a magnetic field or electric field, dispersing or converging the masses.

In each of these mass spectrometers, the ion generation location and the detection location are opposite to each other with a magnetic field in between, so the ion generation process and ion reaction process can be easily monitored.
It is impossible to grasp this right turn, and it is extremely inconvenient for analysis for these purposes.

Therefore, in recent years, attempts have been made to capture and observe ions at the place where they are generated for a relatively long period of time, and the specific means for this is the so-called ion cyclotron resonance mass spectrometry method or its device ( Hereinafter referred to as an ICR mass spectrometer.

) are being considered. Figure 1 shows the outline of this ICR mass spectrometer, in which ions moving circularly in a magnetic field B selectively absorb the energy of an alternating current signal corresponding to a unique resonance frequency. Mass spectra are measured by using acceleration and measuring the response of ions to an alternating electric field.

That is, when a sample (gas molecules) is introduced into a trap cell 1 surrounded by six conductive plates, and electrons emitted by a filament 10 are accelerated by a grid 11 and collided with it, the inside of the trap cell 1 is Ions are generated, and these ions rotate on a plane orthogonal to the magnetic field B at a unique frequency f depending on the ratio of mass m to charge e (hereinafter referred to as m/e value).

Moreover, at this time, if a weak DC voltage with the same sign as the ion charge e is applied to the pair of side plates 2 a and 2 b facing each other in the direction of the magnetic field B, both plates 2 a
, 2b restricts the movement of the ions in the direction of the magnetic field B, and the ions are completely trapped in the trap cell 1.

Furthermore, in this state, upper play) 3a and lower play)
When an alternating current signal is applied between 3b and an alternating electric field is created in between, and the frequency is changed, the ions suddenly increase the orbital radius r of their rotational motion when the signal frequency reaches a certain value. ,To accelerate.

This is because each ion rotates at a unique frequency f depending on its m/e value, so each ion has its own cyclotron resonance frequency with respect to the AC electric field. When the frequency of becomes equal to this resonant frequency,
Cyclotron resonance occurs, and the ions absorb the energy of the alternating current signal, increase the orbital radius r, and accelerate.

Therefore, by scanning while changing the signal frequency while detecting the response of ions to the alternating current electric field, the mass spectrum of the sample trapped in the trap cell 1 can be measured.

In this ICR mass spectrometer, ions can be trapped in the trap cell 1 for a long enough period of time to analyze the chemical phenomena of ions in the gas phase. Effective for analyzing reaction processes.

When measuring a mass spectrum, only ions of the desired species are present, and these ions are exposed to some kind of chemical or
It is assumed that there are no other substances that have a physical effect (hereinafter referred to as contaminants), and therefore the trap cell 1 is installed in a completely sealed chamber with an internal pressure of 10-7 to 1O-8 Torr. It is kept in a highly vacuum state.

Furthermore, great care is taken to ensure that the sample sent to this chamber is free from contaminants.

The sample supply procedure will be explained with reference to Fig. 2.The sample is supplied from the container 20°20... to the leak valve 21.2.
1... to the chamber 15, but at this time, the sample in the container 20.20 is filled with liquid nitrogen a, a
Cool and solidify by...

In this state, first container 20.20...
The contaminants present in the supply paths 22, 22, etc. leading from the leak valves 21, 21, and so on are exhausted by the exhaust means 23, and then the valve 24, 24... are closed, and the sample is sent to the chamber 15 via the leak valves 21, 21... while being vaporized.

The gas in the chamber 15 has been substantially completely removed by the evacuation means 16, so that only the specific sample is sent to the trap cell 1.

Next, when changing the sample to be measured, it is necessary to completely remove the previous sample remaining in the sample supply channels 22, 22, . . . and the chamber 15, and perform a purification process.

During this purification process, the chamber 15, the supply path 22.
22... is heated and the kinetic energy of the gas molecules therein is increased while being exhausted by the exhaust means 16 or 23. In this case, the chamber 15 is in a highly vacuum state. Moreover, since only a specific sample is sent, it can be almost completely purified by processing it for a certain amount of time.

However, the supply channels 22, 22..., in addition to the sample, pass the air contained in the containers 20, 20..., and are extremely contaminated.
Long processing times, typically 24 to 48 hours, are required, which creates a time barrier for sample measurements.

This invention was devised in view of the above-mentioned problems in CR mass spectrometers, and is intended to enable mass spectrum measurements to be carried out more efficiently in a shorter time.

That is, the device according to this invention has a sample supply system that runs from the container containing the sample to the chamber via the leak valve.
An exhaust means is provided to eliminate gas in the supply path by heating and exhausting the supply path, and multiple sample supply systems equipped with this exhaust means are provided, and each sample supply system is selectively connected to the chamber. This allows for free communication between one sample supply system and the other, allowing measurement to be performed using another sample supply system, reducing the time required for measurement and improving This aims to use the equipment efficiently.

Hereinafter, this invention will be explained in detail based on an embodiment shown in FIG.

The trap cell 1 is located in a completely sealed chamber 15 in a magnetic field;
5 is connected to exhaust means 16.

This evacuation means 16 is composed of a fusion pump 17 and a rotary pump 18, and evacuates the gas in the chamber 15 to reduce the pressure to a vacuum state of 10-7 to 10-8' Torr.

Further, the chamber 15 includes a plurality of sample supply systems 19a.
, 19b are connected, and each sample supply system 19a, 19
b can selectively communicate with the chamber 15.

In the illustrated case, two sample supply systems 19a and 19b are connected to a sample supply nozzle 30 facing into the chamber 15 via a three-way valve 31, and by switching the three-way valve 31, each sample supply system 19a , 19b, only one system is communicated with the supply nozzle 30.

Each sample supply system 19a, 19b includes a container 20a, 20a..., 20b, which stores a sample (gas), respectively.
20b...... to leak valves 21a, 21a.
..., 21b, 21b..., one or more supply paths 22a, 22a leading to the three-way valve 31
It consists of ......, 22 b, 22 b,
Containers 20a, 20a..., 20b
, 20 b... from leak valves 21a, 2
1a..., 21b, each supply path 22a, 22a..., 22b up to 21b
, 22 b... have valves 24 a, 24
a..., 24 b, 24 b...
Exhaust means 23 a and 23 b are connected via.

These exhaust means 23a, 23b are a fusion pump 25a.

25b and rotary pumps 26a, 26b are connected, and the supply paths 22a, 22a...
, 22 b , 22 b , . . . are heated and evacuated to expel the gas molecules present in each of these supply channels to the outside.

To supply the sample to the chamber 15 with this device,
In advance, the chamber 15 and each sample supply system 19a.

19b and the sample supply system 19 to be used.
On the a side, containers 20 a, 20 a...
The sample stored in... is cooled and solidified with liquid nitrogen aa...

Next, open the cocks 24a, 24a...
By operating the exhaust means 23a, the sample supply path 22a
, 22 a . . . After substantially completely expelling the gas present in them, the cocks 24 a , 24 a are closed, and the exhaust means 23 a is stopped.

Next, the three-way valve 31 is switched to the sample supply system 19a measurement, and the leak valves 21a, 21a are turned on while heating and vaporizing the samples in the containers 20a, 20a...
The liquid is gradually supplied into the chamber 15 through the wafer.

Next, when the measurement for one type of sample is completed and another sample is to be measured, the chamber 15 is heated to purify it by removing the gas present therein, before introducing the sample. Once completed, another sample supply system 19b can be used to send the sample to the chamber 15 for measurement.

Of course, the sample supply system 19a that has already been used is also purified by exhausting the gas therein while heating its supply path 22a, but the above measurements can be performed in parallel with this purification process. can.

As explained above, according to this invention, when measuring the mass spectrum of a sample with an ICR mass spectrometer,
By using a plurality of sample supply systems one after another, different samples can be sequentially measured once the chamber has been cleaned, without waiting for the sample supply systems that have already been used to be processed.

Therefore, the measurement time can be significantly shortened and the operating efficiency of the apparatus can be improved.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the main parts of an ion cyclotron resonance mass spectrometer, Figure 2 is a piping diagram showing a conventional sample supply system, and Figure 3 is an illustration of an embodiment of this invention. FIG. 1... Trap cell, 15... Chamber, 16, 23 a23 b... Exhaust means, 1
9a, 19b...Sample supply system, 20a, 2
0 b...Container, 21a, 21b...
...Leak valve, 22 a, 22 b...
Supply path, B...Magnetic field.

Claims (1)

[Scope of utility model registration request] It is equipped with a trap cell placed in a magnetic field in a certain direction within a chamber, and an evacuation means for making the inside of the chamber a vacuum state, and a gaseous sample is sent into the chamber that is in a highly vacuum state. This sample is ionized in a trap cell, and the generated ions are caused to move in a circular motion in a magnetic field, and are captured in the cell by this magnetic field and an electric field applied to the trap cell. In this state, an alternating current signal is applied to the trap cell. In an ion cyclotron resonance mass spectrometer that detects ions by detecting the response of ions in an alternating magnetic field, the sample supply system runs from a container containing a sample to a chamber via a leak valve. An exhaust means is provided to eliminate gas in the supply path by heating and exhausting the gas, and a plurality of sample supply systems equipped with this exhaust means are provided, and each sample supply system can be selectively communicated with the chamber. sample supply device.