JPS5829560Y2 - mass spectrometer - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a mass spectrometer, particularly to a sample gas introduction section of a chemical ion source mass spectrometer.

In a conventional electron impact ion source type mass spectrometer, the gas pressure at the sample gas introduction section is approximately 1 mm 1 g, the gas pressure at the electron impact ion source is IXI()-3 mmHg, and the gas pressure at the analysis tube is approximately I x 10-6 mmHg. The gas pressure decreases as the sample gas enters the direction.

Therefore, the sample gas introduced into the sample gas inlet can reach the ion detector without any trouble according to the gas pressure gradient.

On the other hand, in a chemical ion source type mass spectrometer, the gas pressure in the ionization chamber is around 1iiHg, which is suitable for ionizing the reaction gas button and the sample gas. The sample gas cannot be introduced into the ionization chamber unless the gas pressure is increased.

In particular, when switching between a chemical ion source and an electron impact ion source in one ionization chamber (ion source), the gas pressure in the sample gas introduction section must be switched quickly.

Conventionally, for this purpose, air was introduced into the sample gas introduction section to increase the gas pressure, or a large amount of sample gas was introduced into the sample gas introduction section to increase the gas pressure at the sample gas introduction section.

However, introducing air to increase the gas pressure in the sample gas introduction section causes various trace component gases contained in the air to mix in with mass spectrometers that detect extremely small amounts, resulting in increased background. Furthermore, if there is only a small amount of sample, it is not possible to introduce a large amount of sample into the sample gas introduction section, and therefore the gas pressure cannot be increased sufficiently.

The present invention attempts to solve the above-mentioned problems by introducing the reactive gas introduced into the chemical ion source into the sample gas introduction section, and by adjusting the gas pressure between the ionization chamber and the sample gas introduction section in advance. An object of the present invention is to provide a mass spectrometer that can easily introduce the sample gas into a chemical ion source by keeping the sample gas at approximately the same level and increasing the gas pressure in the sample gas introduction section with the injected sample gas. It is something to do.

That is, an ionization chamber, a reaction gas flow path for introducing a reaction gas into the ionization chamber, and a sample gas introduction flow having a sample gas introduction part in the flow path for introducing the sample gas into the ionization chamber. The mass spectrometer has a configuration in which the sample gas introduction channel is connected to the above-mentioned reactant gas source.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, 1 is a reactive gas source, 2 and 14 are gas pressure regulators for the reactive gas, 3 is a chemical ion source, 3' is an ionization chamber of the chemical ion source 3, and 4 is a reactive gas source for the chemical ion source 3. 5 is a heating sample introduction device (sample gas introduction section); 6 is a heating sample introduction device 5;
7 is a gas flow path for introducing a reaction gas into the heating sample introduction device 5 branched from the flow path 4, 8 is an orifice, 10 and 11 are vacuum balloons, and 9 is an orifice 8 and a vacuum. This is a gas channel for introducing the sample gas into the ionization chamber 3' of the chemical ion source 3 via the valve 10, and these channels 7 and 9 can be called sample gas introduction channels.

12 is a sector-type analysis tube for analyzing ions from an ion source, 13 is a detection device for ions separated by the sector-type analysis tube, and 15 is a heater for vaporizing the liquid sample injected into the heating sample introduction device. .

A reaction gas from a reaction gas source 1 whose pressure has been adjusted to an appropriate pressure by a gas pressure regulator 2 is introduced into a chemical ion source 3 via a flow path 4 .

The inside of the ionization chamber 3' of the chemical ion source 3 is maintained at a gas pressure suitable for ionizing the reaction gas (usually 0.5 mmHg to 2
miHg), and a portion of the introduced reactant gas is ionized.

On the other hand, the heated sample introduction device 5 is once evacuated to a low vacuum via the vacuum pulp 11, and then a reactive gas from the reactive gas source 1 is introduced through the channel 7.

The gas pressure inside the heated sample introduction device 5 is maintained at approximately the same level as the gas pressure inside the chemical ion source 3 by adjusting the gas pressure regulator 14 .

A liquid sample injected from the sample injection port 6 is vaporized by a heater 15 for heating.

By vaporizing this liquid sample, the gas pressure within the heated sample introducing device 5 is further increased by the sample gas.

Therefore, the gas pressure in the heated sample introduction device 5 is higher than the gas pressure in the ionization chamber 3', so this mixed gas of sample gas and reaction gas is introduced into the ion source 3 through the orifice 8 button and the flow path 9. .

(From a different perspective, the sample gas is introduced into the chemical ion source 3 by a carrier gas called a reaction gas.

) Since the orifice 8 is interposed between the heating sample introduction device 5 and the ion source 3, the mixed gas is introduced into the ionization chamber 3' little by little over a long period of time.

The vacuum pulp 10 serves as a barrier between the chemical ion source 3 and the sample heating introduction device 5.

Of the mixed gas introduced into the ionization chamber 3' of the chemical ion source 3, sample gas components are ionized by an ion-molecule reaction with the ionized reaction gas.

The ionized sample gas (also the ionized reaction gas) is introduced into the analysis tube 12, separated according to its mass, and detected by the detection device 13.

The gases introduced into the chemical ion source 3 are only the sample gas and the reaction gas, and since they are introduced in small quantities, the ionization chamber 3
It does not affect the gas pressure suitable for ionization of However, it goes without saying that a configuration using a solid sample introduction device or a gas sample introduction device may also be used.

Furthermore, the analysis tube is not limited to the sector type, but may be replaced with a quadra-ball type analysis tube.

As detailed above, the present invention introduces a reactive gas into the sample introduction device and maintains the gas pressure in the sample gas introduction section at approximately the same level as the ionization chamber of the chemical ion source. In addition to making introduction into the ion source extremely easy, analysis data with little background can be obtained with a small sample. Therefore, it can be said that the effect is sufficiently large for practical use.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention. 1... Reaction gas source, 2, 14... Gas pressure regulator, 3... Chemical ion source, 3'.
- Inter-ionization chamber, 4, 7, 9... Gas flow path, 5
... Heating sample introduction device, 6 ... Sample injection port, 8 ... Orifice, 10.11 ...
・・Vacuum valve, 12・・Curved sector type analysis tube, 13・・
...Detection device, 15...Heater.

Claims (1)

[Scope of utility model registration request] There is an ionization chamber that ionizes a sample through an ion chemical reaction and electromagnetically separates and analyzes the sample ions.
It has a reaction gas flow path for introducing a reaction gas into this ionization chamber, and a sample gas introduction part for introducing a sample gas into the ionization chamber, and this sample gas introduction part is connected to a reaction gas source and an ionization chamber. 1. A mass spectrometer characterized in that the sample gas is inserted into a sample gas introduction flow path that connects the ionization chamber, and the sample gas is introduced into the ionization chamber using a reaction gas as a carrier gas.