JPH0228225B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for blocking gas flowing from the chromatograph into the mass spectrometer in a chromatograph mass spectrometer.

In a chromatograph mass spectrometer, in order to prevent carrier gas, solvent, etc. from flowing into the mass spectrometer, the gas flow path connecting the chromatograph and mass spectrometer is closed except during periods when sample components are flowing out from the chromatograph. That's what I do. For this reason, a plate is provided between the opposing nozzles of a jet-type molecular separator for removing carrier gas, which is installed between the chromatograph and the mass spectrometer, so that it can be moved in and out to block the flow of gas into the mass spectrometer. A gas flow blocking device is used in which the plate is advanced between opposing nozzles. However, in conventional devices of this kind, the plate was mechanically operated from outside the vacuum, so the structure was complicated to maintain airtightness, and the plate was fixed to a rod that held the plate. Even when positioned between the opposing nozzles, there is a gap between the nozzle and the plate, which does not completely block the gas flow into the mass spectrometer, and the plate is pushed by the airflow ejected from the chromatograph side nozzle. Because the plate was attracted to the nozzle on the mass spectrometer side, which was in a high vacuum, the attachment between the plate and the holding rod was bent or sometimes broke. The present invention attempts to solve the above-mentioned problems of conventional devices.

The present invention allows the plate to be operated by an electromagnet in a vacuum, that is, in a space communicating with the internal space of the molecular separator, and also allows the plate to be freely coupled to the movable iron core of the electromagnet, so that no force is applied to the plate. To provide a gas flow cutoff device that avoids the action of the gas flow and allows the plate to freely follow the end face of the nozzle on the mass spectrometer side. The present invention will be explained below with reference to Examples.

FIG. 1 schematically shows the configuration of a gas chromatograph mass spectrometer. 1 is a chromatographic column, 4
is a mass spectrometer, and in a gas flow path connecting the two, 2 is a molecular separator, and 3 is a gas flow cutoff device. The molecular separator and the gas flow cutoff device are each connected to an exhaust pump (not shown). FIG. 2 shows an embodiment of the present invention. In FIG. 2, the molecular separator shown in FIG. 1 is connected to the right side, and the mass spectrometer is connected to the left side. Therefore, in this figure, the direction of gas flow is from right to left. 5 is a chromatograph side nozzle, 6 is a mass spectrometer side nozzle facing the nozzle 5, and the space surrounding these nozzles is connected to an exhaust pump (not shown) via an exhaust pipe 12. Reference numeral 7 denotes a gas flow blocking plate, which is suspended from the lower end of a holding rod 8 attached to the movable iron core 9 of the electromagnet. The movable iron core 9 is housed in a guide tube 15, and the guide tube 15 is airtightly attached to the electromagnet device main body 16. Therefore, the iron core 9 is in a space that is cut off from the outside air and communicated with the gas flow path, and the electromagnet winding 10 is placed outside the guide tube 15.
is attached and operated from outside the vacuum. The figure shows winding 1
The plate 7 is lowered between the opposing nozzles 5 and 6 and closes the end of the nozzle 6. Winding wire 10
When energized, the iron core 9 is pulled up, thereby pulling the plate 7 upward from between the nozzles 5 and 6.

FIG. 3 shows the connection structure between the plate 7 and the rod 8. The lower end of the rod 8 becomes a fork 13, and from both legs of the fork 13, an arm 1 extends horizontally to the left in Figure 2.
4 is projected, and the plate 7 is loosely suspended from this arm by means of the hole 14'. Therefore, the plate 7 can swing and move along the arm 14.
In the figure, it can move in the left-right direction, that is, in the axial direction of the nozzles 5 and 6. Therefore, in the gas flow cutoff position shown in FIG. 2, the gas flowing out of the molecular separator (not shown in the figure on the right side) collides with the plate 7 again as a jet by the nozzle 5, and the plate 7 is pushed to the left and impinges on the nozzle 6. Since the left side of the nozzle 6 is in a high vacuum due to the mass spectrometer, the plate 7 is easily attracted to the end face of the nozzle 6 and completely closes the opening of the nozzle 6. The gas ejected from the nozzle 5 diverges when it hits the plate 7, passes through the exhaust pipe 12, and is exhausted by an exhaust pump (not shown).

The device of the present invention has the above-described configuration, and the plate 7 is attached to the end of the support rod in a suspended state so that the nozzle can be moved in the axial direction. No unreasonable force is applied to the plate, and the plate is freely adsorbed along the opening edge of the high vacuum side nozzle, so gas is completely blocked.For example, in Figure 1, when column 1 is removed and the right side of plate 7 is Even when the pressure on the high vacuum side (in Figure 2) reaches atmospheric pressure, the vacuum on the high vacuum side can be maintained, and since there is no rigid connection between the plate and the holding rod, the There are no problems such as bending or breakage of the joint, and the reliability is high, and the structure is simple and inexpensive.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of a gas chromatograph mass spectrometer, FIG. 2 is a longitudinal sectional side view of an apparatus according to an embodiment of the present invention, and FIG. 3 is a perspective view of the main parts of the above. 5, 6... Opposing nozzle, 7... Plate for blocking gas flow, 8... Rod holding plate 7, 9...
...Iron core, 10...Electromagnet winding, 15...Guide tube for iron core 9.

Claims (1)

[Claims] 1. In a chromatograph mass spectrometer in which a plate for blocking gas flow is provided in a freely removable manner between opposing nozzles provided in the middle of a gas flow path connecting a chromatograph and a mass spectrometer, the above plate is used as a plate. A gas flow cutoff device for a chromatograph mass spectrometer that is held by a holding rod so that it can move freely in the axial direction of the nozzle.