JPH0552811A - Process mass spectrometer - Google Patents

Abstract

PURPOSE:To continuously supply specific gas to a mass spectrometer by placing a pipe equipped with a selection film for selectively passing only specific gas components through a gas flow path. CONSTITUTION:Sample flows in a direction indicated by arrows, and when it comes into contact with a gas selection film 4, only specific components transmit through the film 4 to enter a pipe 1. If an opening degree of a solenoid valve 5 is adjusted so that a ratio of the pipe 1 and a split tube 11 is 1:10 for example, 1/10 amount of the specific gas which entered the pipe 10 enters an ion source 2 of a mass spectrometer MS. However when there is no deterioration possible in vacuum of the spectrometer MS and a sampled amount is small, the valve 5 is adjusted so that the tube 11 is closed. Gas which entered the ion source 2 is subjected to electrical impact to be ionized, and if a scan mode of the spectrometer MS is set to SIM(single ion monitoring), continuous analysis of the gas which transmitted through the film is possible. When components of gas to be analyzed are to be changed, the film 4 is appropriately replaced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mass spectrometer for a process in which a gas component in a gas channel is continuously introduced into a mass spectrometer for analysis.

[0002]

2. Description of the Related Art Conventionally, when a gas from a pipe of a chemical plant is analyzed by a mass spectrometer, the gas is once collected from the pipe by a sampling device, separated into each component by a gas chromatograph, and then the mass spectrometer. Is being introduced to.

There is also a process gas chromatograph for continuously sending a gas from a pipe of a chemical plant to a gas chromatograph, but this is not connected to a mass spectrometer.

[0004]

Among the conventional methods, the method of once sampling gas from a pipe with a sampling device is as follows.
Since only the collected portion could be analyzed by the mass spectrometer, the gas components could not be continuously analyzed, which was not suitable for plant management. Moreover, there was a time lag between the sampling of gas and the introduction of the analyzer, and accurate analysis could not be performed on a sample in which the reaction continued.

It is also conceivable to connect a mass spectrometer to the process gas chromatograph and continuously monitor the gas component from the pipe. However, the eluate from the process gas chromatograph contains a large amount of carrier gas. Since it was included, the eluate containing the specific gas could not be directly introduced into the mass spectrometer, and it was necessary to insert a jet separator or the like in front of the mass spectrometer to separate the carrier gas.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a mass spectrometer for a process in which a gas flowing in a pipe or the like of a chemical plant can be sampled online and introduced into a mass spectrometer. To do.

[0007]

In order to solve the above-mentioned problems, the present invention provides a gas flow path with a pipe having one end connected to an ion source of a mass spectrometer, and a gas flow of the pipe. It is characterized in that a gas selective membrane is attached to the roadside opening.

The term "gas flow path" as used herein means a flow path in which a plurality of component gases are continuously flowing, such as piping in a chemical plant. To arrange a pipe in a gas flow path, for example, a method of directly making a hole in a pipe of a chemical plant, inserting a pipe to which a pipe is connected in advance and fixing the pipe with a flange, etc. However, the present invention is not limited to these.

The material of the pipe arranged in the gas flow path is appropriately selected in consideration of corrosiveness, pressure resistance, etc., and SUS or the like is used. The pipe diameter is determined in consideration of the amount of gas to be sampled and the influence on the vacuum degree of the mass spectrometer. The position of the pipe arranged in the gas flow path is preferably a position facing the gas flow and at the maximum flow velocity point in the flow path. In order not to deteriorate the vacuum degree of the mass spectrometer, a solenoid valve may be provided in the middle of the pipe and the flow rate of gas sent to the mass spectrometer may be adjusted by adjusting the opening / closing degree of the solenoid valve.

The gas selective membrane has a property of allowing only a gas of a certain component to permeate from a plurality of mixed gases (the gas permeability of only a certain component is large as compared with other gas components),
A dense polymer film is used. For example, a membrane of cellulose acetate and polyethylene is permeable to n-butyl alcohol, polyethylene (low density) is hexane, a membrane of cellophane and polyethylene is permeable to ethyl alcohol, and polyethylene (high density) is permeable to chloroform and hexane. Let The gas-selective membrane is not limited to the above, and can be appropriately selected depending on the type of gas. When it is desired to obtain a gas having a plurality of components at the same time, a plurality of membranes may be used in combination.

The gas selective membrane may be attached, for example, by fixing the membrane to the four corners of the pipe opening with a pin or adhering the membrane with an adhesive, but is not limited thereto.

[0012]

In the present invention, since the pipe provided with the gas selective membrane that selectively permeates only the specific gas component is provided in the gas flow path, the specific gas can be continuously sent to the mass spectrometer. You can

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of the process mass spectrometer of the present invention. 1
Is a pipe for gas sampling, one end of which is directly connected to the ion source 2 of the mass spectrometer MS. The ion source 2 and the pipe 1 are connected to each other by providing an opening in the ion source 2, inserting the pipe 1 therein, and sealing it with an O-ring or the like. The ion source 2 is one that is ionized by, for example, electron impact, and has a filament 3 installed therein. In addition, 7 is a quadrupole electrode of the analysis part of MS, 8 is a detector of MS, 9 is M
It is an exhaust pump for adjusting the vacuum degree of S.

The other end of the pipe 1 is connected to a pipe 10 through which a sample flows in a chemical plant or the like. The pipe 1 is connected to the pipe 10 by making a hole in the pipe 10 and inserting the pipe 1 there. In this case, the sample is sealed by a known method so as not to leak from the pipe connection hole. When the sample flowing through the pipe is a liquid, heating means (not shown) is provided near the pipe 1 so that the sample can be heated and vaporized. The heating means may be one in which a heater wire is simply wound around the outer circumference of the pipe.

A gas selection film 4 is attached to the opening of the pipe 1 on the pipe 10 side, and the gas selection film to be attached is selected according to the type of gas to be sampled.

Further, in this embodiment, in order to prevent the vacuum degree of the MS from being deteriorated, the branch pipe 11 is provided from the middle of the pipe 1 via the solenoid valve 5. A vacuum pump 6 is connected to the other end of the branch pipe 11, and by adjusting the opening / closing degree of the solenoid valve 5 (adjusting the opening degree to the pipe 1 and the branch pipe 11), the MS
The amount of gas entering can be adjusted.

Next, the operation of the embodiment shown in FIG. 1 will be described. The sample is flowing in the direction of the arrow in the figure, and the sample is the gas selective membrane 4
By contacting with, only a specific gas component permeates the gas selective membrane 4 and enters the pipe 1. At this time, the solenoid valve 5
For example, if the openings of the pipe 1 and the branch pipe 11 are adjusted to be in a ratio of 1 to 10, 1/10 of the specific gas entering the pipe 1 will be the ion source of the mass spectrometer MS. Two
Will enter. However, when there is no concern that the degree of vacuum of the mass spectrometer MS is deteriorated and the sampled sample amount is small, the solenoid valve 5 is adjusted so that the circuit on the side of the branch pipe 11 is all closed.

The gas that has entered the ion source 2 undergoes an electron impact there and is ionized. By setting the scanning mode of the mass spectrometer MS to SIM (single ion monitoring), the gas that has permeated the membrane can be continuously analyzed.

When it is desired to change the gas component to be analyzed, the gas selective membrane 4 need only be replaced appropriately.

[0020]

According to the present invention, a gas of a specific component can be continuously sampled and sent to a mass spectrometer, so that it is possible to continuously measure a sample component flowing through a pipe of a chemical plant or the like.

Further, a specific component is separated by a membrane,
A gas separator such as a gas chromatograph becomes unnecessary.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus of the present invention.

[Explanation of symbols]

 1: Pipe 2: Ion source 4: Gas selective membrane 5: Solenoid valve MS: Mass spectrometer

Claims (1)

[Claims] 1. A process characterized in that a pipe, one end of which is connected to an ion source of a mass spectrometer, is provided in a gas flow channel, and a gas selective membrane is attached to an opening of the pipe on the gas flow channel side. Mass spectrometer.