JP2727621B2 - Interface for GC / MS - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial application field The present invention relates to a gas chromatograph-mass spectrometer (GC).
/ MS) interface. For more information, see G
The present invention relates to a GC / MS interface for introducing a sample in a sample gas from C into a mass spectrometer at a predetermined ratio.

(B) Conventional technology Conventionally, as a GC / MS interface, a container provided with an exhaust port for decompression or an inlet and an exhaust port for purge gas, and a gas chromatograph separation column which is extended and inserted into the above container and connected. A sample gas introduction pipe, and a sample discharge pipe extending from the mass spectrometry section, inserted and connected into the container, and having a gas inlet arranged at a position facing the gas outlet of the sample gas introduction pipe. Interfaces for sample gas splitting are widely used.

In such an interface for GC / MS, usually,
In order to introduce the sample component into the sample discharge pipe stably and efficiently at a predetermined split ratio, each of these pipe lines is fixed around the gas outlet of the sample gas inlet pipe and the gas inlet of the sample discharge pipe. A cylindrical flow path protection means is extrapolated and installed at an interval of. The split ratio of the sample gas to the mass spectrometry system in the GC / MS interface was regulated by the above-mentioned fixed interval.

(C) Problems to be Solved by the Invention In such a conventional interface for GC / MS, in order to change the split ratio of the sample gas, the flow rate of the purge gas for the carrier gas split in the interface container and the pressure reduction for the pressure reduction are used. It is necessary to change the displacement of the vacuum pump.

However, according to such a method, the structure becomes complicated and miniaturization is difficult, and in the former, tailing occurs in the detection peak, and in the latter, functional destruction due to a change in the degree of vacuum in the mass spectrometry system or vacuum vessel There is a problem that contamination in the interior is newly generated.

On the other hand, changing the split ratio of the sample gas necessitates the need to cut the solvent component peak (so-called solvent cut) and the compatibility between the concentration of the analyte in the sample gas and the detection range in the mass spectrometry system. Is essential in that respect.

The present invention has been made under such circumstances, and it is possible to change the split ratio of the sample gas, that is, the amount of the sample gas supplied to the mass spectrometry system, without changing the flow rate of the purge gas for splitting or the evacuation amount. It aims to provide an interface for / MS.

(D) Means for Solving the Problems Thus, according to the present invention, (a) a container provided with an exhaust port for decompression or an inlet and an outlet for purge gas,
(B) a sample gas introduction pipe extending from the separation column for gas chromatography and inserted into and connected to the vessel; and (c) a sample gas introduction pipe extending from the mass spectrometer and inserted and connected into the vessel. A sample exhaust pipe having a gas inlet arranged at a position facing the gas outlet of (a), (d) the sample gas inlet pipe and the sample exhaust pipe, and a sample gas split flow path set between the gas outlet and the gas inlet (E) a flow path protection means comprising a cylindrical body movably extrapolated around the
Control means for controlling the movement of the flow path protection means between the coating position and the non-coating position of the sample gas split flow path,
An interface for GC / MS comprising:

In the GC / MS interface of the present invention, the cylindrical flow path protection means conventionally arranged in the container is configured to be movable, and this is shifted to the uncovered position or the partially covered position of the sample gas split flow path. It is provided with a control means that can be used. Here, various actuators can be applied as the control means, but when the flow path protection means is made of a magnetic material such as steel, it is suitable to use an electromagnet such as a solenoid coil in combination. An example is shown in the embodiment described later.

In the GC / MS interface of the present invention, nitrogen, helium, argon, or the like can be used as a purge gas when a purge gas is used, and it is generally preferable to use the same type as the GC carrier gas.

(E) Action The control means acts to shift the flow path protection means for covering the sample gas split flow path to a non-covering position or a partial covering position of the split flow path. As a result, the discharge amount of the introduced sample to the exhaust port for depressurization or the purge gas outlet changes, and as a result, the split ratio of the sample gas changes without changing the flow rate of the purge gas or the discharge amount of the vacuum pump. Becomes

(F) Embodiment 1 shown in FIG. 1 shows an interface for GC / MS of the present invention. As shown in the figure, the GC / MS interface 1 is constituted by inserting and connecting a sample gas inlet pipe 5 and a sample outlet pipe 6 into a cylindrical container 4 having a helium gas inlet 2 and an outlet 3. The gas outlet and the gas inlet are arranged facing each other at an interval of about 2 mm, and a sample gas split flow path is formed between them.

A flow path protection made of a cylindrical magnetic material that is externally inserted into the container 4 at a predetermined interval (for example, 0.2 to 0.5 mm) between the sample gas introduction pipe 5 and the sample discharge pipe 6 to cover the split flow path. Means 7 are provided, and the flow path protection means 7 is coaxially movable left and right. Two solenoid coils 8, 9 are wound around the outer periphery of the container 4, and an external power supply 11 is connected to these coils 8, 9 via a changeover switch 10. In the normal state, the switch 10 is set to the position a, whereby the solenoid coil 8 operates to hold the flow path protection means 7 at a position (solid line position) covering the sample gas split flow path. . In this state, the sample gas introduced into the container is then introduced into the opposed sample discharge pipe 6, but the carrier gas in the sample gas is slightly separated by the helium gas passing through the gap with the flow path protection means 7. The sample component is efficiently introduced into the sample discharge pipe 6 to the extent that the sample is discharged.

In the interface 1, for example, when an excessively concentrated sample is introduced into the container, the switch 11 is set to b
Is switched to the position, the solenoid coil 9 acts in place of the solenoid coil 8, and the flow path protection means 7 moves to the broken line position 7 '. As a result, the sample gas split flow path becomes uncoated, and most of the excess sample diffuses into the container and is discharged from the outlet 3 to the outside.
Excessive introduction of the sample into the sample is prevented.

In addition, by holding the flow path protection means at an intermediate position between the coating position and the non-coating position, the amount of sample introduced can be appropriately adjusted within the above range.

Therefore, it is possible to easily adjust the sample gas introduction amount according to the solvent cut or the spot.

When using the interface for GC / MS of the present invention, an ordinary jet separator or the like may be connected at the subsequent stage.

(G) Effects of the Invention According to the interface for GC / MS of the present invention, the split ratio of a sample gas can be easily changed, and the introduction of a sample gas having a concentration unsuitable for mass spectrometry into a mass spectrometry system can be prevented. it can. Further, since the above control can be performed without changing the flow rate of the purge gas in the container or the amount of vacuum evacuation, tailing and contamination due to the control do not occur, and the apparatus configuration is advantageous.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing one embodiment of a GC / MS interface of the present invention. 1 ... GC / MS interface, 2 ... He gas inlet, 3 ... He gas outlet, 4 ... Container, 5 sample gas inlet tube, 6 ... Sample outlet tube, 7 ... Flow channel protection means , 8,9 ... solenoid coil, 10 ... changeover switch, 11 ... external power supply.

Claims (1)

(57) [Claims] 1. A container provided with (a) an exhaust port for reducing pressure or an inlet and an outlet for purging gas, and (b) a sample gas introduced from a separation column for gas chromatography and inserted and connected into the container. A tube, (c) a sample discharge tube extending from the mass spectrometry unit, inserted and connected into the container, and having a gas inlet disposed at a position facing the gas outlet of the sample gas inlet tube, (d) the sample discharge tube (E) a sample gas introduction pipe and a sample discharge pipe, and a flow path protection means comprising a cylindrical body movably extrapolated around a sample gas split flow path set between the gas outlet and the gas inlet; A) control means for controlling the movement of the flow path protection means between the coating position and the non-coating position of the sample gas split flow path.