JP2007024781A - Gas chromatograph device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To introduce the more sample quantity when introducing a large quantity of sample into a gas chromatograph, and to perform maintenance of a pre-column part without stopping vacuum of a detector part. <P>SOLUTION: A passage switching valve capable of switching a passage for connecting a passage from a column on the valve upstream side to a column on the valve downstream side and connecting a passage from a carrier gas passage to a discharge port, and a passage for connecting the passage from the column on the valve upstream side to the discharge port and connecting the passage from the carrier gas passage to the column on the valve downstream side are provided in the middle of the column. The valve can be switched at a timing of sample injection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a gas chromatograph apparatus (hereinafter referred to as “GC”).

In the gas chromatograph apparatus, a sample inlet is provided at the column inlet, and the sample vaporized in the sample inlet is placed on a carrier gas and sent into the column. When the target component contained in the sample is a very small amount, it is necessary to feed as much sample as possible into the column. Conventionally, on-column methods and PTV (Programmed Temperature Vaporizer) methods have been used as methods suitable for such a large sample introduction, and these methods are called large sample introduction methods. According to the large sample introduction method, in a general splitless method, the injection amount is limited to about 2 μl, but a sample of 10 μl or more can be introduced.

FIG. 3 is a flow path configuration diagram of GC using the conventionally used on-column method. A carrier gas introduction part 11 is connected to the sample introduction part 10 provided with a septum 13 at the head, and a carrier gas having a predetermined flow rate is caused to flow through a pre-column 18 that is inserted deeply under the septum 13. A separation capillary column 20 is connected to the outlet of the precolumn 18 through a three-way joint 14, and a detector 22 is provided at the outlet of the capillary column 20. A discharge passage 15 provided with a valve 16 is connected to the remaining opening of the three-way joint 14. Usually, the precolumn 18 has a larger diameter than the capillary column 20 (for example, the precolumn has an inner diameter of about 0.5 mm and the capillary column has an inner diameter of about 0.2 to 0.3 mm), and the precolumn 16 and the capillary column 20 are placed in the column oven 21. It is stored.

At the time of sample injection, the temperature of the column oven 21 is set to a temperature near the boiling point of the solvent of the liquid sample, and the valve 16 is opened. The needle at the tip of the syringe 23 is passed through the septum 13 and the liquid sample is directly introduced into the precolumn 18. The liquid sample injected in large quantities once spreads over a wide area and adheres to the inner wall of the precolumn 18. The solvent in the liquid sample is gradually vaporized and rides on the carrier gas flow and is discharged to the outside through the discharge path 15. Since the boiling point of the target component is higher than the boiling point of the solvent, it is concentrated as the solvent vaporizes and remains on the inner wall of the precolumn 18. After injecting a predetermined amount of the liquid sample and discharging most of the vaporized solvent, the valve 16 is closed. Then, when the temperature of the column oven 21 is raised according to a predetermined profile, the low boiling point components in the sample adhering to the inner wall of the precolumn 18 are sequentially vaporized and sent to the capillary column 20 along the carrier gas flow. When passing through the capillary column 20, each component is clearly separated and reaches the detector 22.

FIG. 4 is a flow path configuration diagram of GC using the PTV method. A substantially cylindrical glass insert 30 filled with a filler 31 is disposed in the sample introduction part 10 provided at the inlet of the capillary column 20. In addition to the carrier gas introduction part 11, a split flow path 33 provided with a split valve 32 is connected to the sample introduction part 10. A heater 12 is provided around the sample introduction unit 10 so that the temperature can be controlled independently of the column oven 21.

At the time of sample injection, the sample introduction unit 10 is set near the boiling point of the solvent, and the split valve 32 is opened. When a liquid sample is injected from the syringe 23 into the sample introduction unit 10, the liquid sample is once carried on the filler 31. The solvent in the liquid sample carried on the filler 31 is gradually vaporized, rides on the carrier gas flow, and is discharged to the outside through the split flow path 33. The target component in the liquid sample remains in the filler 31 without being vaporized because of its higher boiling point or due to the holding power of the filler. Thereafter, when the temperature of the sample introduction unit 10 is increased by closing the split valve 32, the low boiling point components supported on the filler 31 are sequentially vaporized and are sent into the capillary column 20 along the carrier gas flow.

As an invention using such a PTV method, there is an invention in which an insertion amount can be increased by providing an insert with a spiral groove cut in a sample introduction portion. (For example, Patent Document 1)

JP-A-11-83822

When performing a large amount of sample injection, it is generally possible to perform a microanalysis and a high sensitivity analysis by increasing the amount of the sample to be injected. However, since the amount of the solvent introduced at the same time also becomes large, the volume greatly increases when the solvent is vaporized in the sample introduction part, resulting in pressure fluctuation in the column. Especially when a mass spectrometer that needs to be used in a vacuum is used as the detector, the pressure at the column inlet increases and the degree of vacuum becomes worse or the detector becomes unstable. There is a limit to the amount of sample introduced due to adverse effects such as. In the conventional example as described above, part of the solvent component is discharged out of the flow path by opening the valves 16 and 32 during sample injection. However, it is only discharged due to the pressure difference between the capillary column provided in the next stage and the discharge flow path, and when the amount of solvent introduced increases, the amount of solvent introduced into the analytical column and detector also increases. It will increase.

In addition, in the analysis using a gas chromatograph, non-volatile components in the sample may remain and the column may be contaminated, and the pre-column may be periodically replaced or the column is particularly susceptible to contamination near the inlet. It is necessary to cut the vicinity of the column entrance by several centimeters. In particular, when a large amount of sample is injected, since the amount of sample introduced into the column increases, contamination is likely to occur, and the contaminated portion needs to be replaced frequently. However, when using a vacuum detector such as a mass spectrometer for the detector, for example, opening the inlet to the atmosphere with the column outlet still connected to the vacuum will cause deterioration of the column. When performing this, it was necessary to once stop the vacuum. Usually, the operation of stopping the vacuum is a time-consuming operation, and it takes a long time to obtain a stable vacuum again. Therefore, the replacement of the contaminated portion is an operation that requires a long time.

A gas chromatograph apparatus having a sample introduction section capable of introducing a large amount of sample, a column section communicating with the sample introduction section, and a flow path switching valve in the middle of the column section, wherein the flow path switching valve is located upstream of the valve Connect the flow path from the column to the column downstream of the valve, connect the flow path from the carrier gas flow path to the discharge port, and connect the flow path from the column upstream of the valve to the discharge port. The flow path connecting the flow path from the path to the column downstream of the valve can be switched.

When a large amount of sample is injected by the on-column method or the PTV method, a large amount of solvent is introduced at the same time. According to the present invention, almost all the solvent is discharged out of the flow path. It is possible to introduce only the components into separation columns and detectors

The contaminated portion of the column can be replaced while supplying the carrier gas to the separation column and the detector, and the contaminated portion can be replaced without stopping the vacuum.

When a large amount of sample is injected, a large amount of solvent is introduced at the same time. According to the present invention, almost all the solvent is discharged out of the flow path, and only the target component is separated into a separation column or detector. It is possible to introduce to. Therefore, the amount of the sample to be injected can be increased without being limited by the amount of the solvent introduced into the separation column and the detector, and a highly sensitive analysis can be performed with a smaller amount. In addition, when a GPC (gel permeation chromatograph) device or a liquid chromatograph device is connected and the eluate from the liquid chromatograph device is introduced into the gas chromatograph device, there are restrictions on the amount of sample introduced into the gas chromatograph device. Therefore, it is possible to expand the selection range of the column size and mobile phase of the liquid chromatograph apparatus.

In addition, according to the present invention, it is possible to replace the contaminated portion of the column while continuing to supply the carrier gas to the separation column and the detector, and the contaminated portion is replaced without stopping the vacuum. be able to. The operation of stopping and restarting the vacuum is a time-consuming operation. Since the contaminated part can be replaced while the vacuum is maintained, the time required for the replacement operation can be greatly reduced.

Hereinafter, an embodiment of a gas chromatograph apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram centering on the GC flow path of the present embodiment, and FIG. 2 is a schematic view 2 of a flow path switching mechanism used in this GC.

The sample introduction unit 10 serves to introduce a carrier gas into the column and guide the needle of the syringe 23 for injecting the sample into the column. Although 18, 19 and 20 are columns, 18 and 19 have a role of dividing a sample introduced in a liquid state into a solvent component and a component to be analyzed, and 18 and 19 are columns having different properties, for example, A column having no holding force as 18 and a column having a holding force as 19 may be attached. Reference numeral 20 denotes a separation column, and, for example, a mass spectrometer is connected as a detector 22 downstream thereof.

Between the column 19 and the column 20, the carrier gas channel 2 and the discharge channel 15 are connected by the channel switching valve 1. FIG. 2 shows details of the flow path switching valve 1. The flow path from the column 19 upstream of the valve (sample inlet side) can be switched to the flow path to the separation column 20 downstream of the valve (detector side) and the discharge flow path 15. Can be switched between the flow path to the separation column 20 and the discharge flow path 15. It is preferable to use the same carrier gas that is introduced from the carrier gas introduction unit 11 into the carrier gas flow path 2, and for example, He is used.

The operation at the time of sample introduction in the GC of the present embodiment having the above configuration will be described. Before the sample introduction, as shown in FIG. 2 (a), only a constant flow of carrier gas is supplied from the carrier gas introduction unit 11 to the sample introduction unit 10, and the flow path switching valve 1 is connected from the column 19. The flow path from the carrier gas flow path 2 is connected to the discharge flow path 15. Further, the temperature of the column oven 21 is set to a temperature slightly higher than the boiling point in the vicinity of the boiling point of the solvent.

At the time of sample introduction, as shown in FIG. 2B, the flow path switching valve 1 is switched, the flow path from the column 19 is connected to the discharge flow path 15, and the flow path from the carrier gas flow path 2 is separated from the separation column. 20 is connected. When the sample is introduced into the column 18 by the sample introduction unit 10, the column 18 is a column having no holding force. Therefore, the sample has a low boiling point in the column 18 along with the flow of the carrier gas. Continue on.

A column having a holding force is used as the column 19, and a component eluted from the column 18 is held at a portion close to the column inlet of the component 19 having a boiling point higher than that of the solvent. The solvent component and some of the low-boiling components travel on the carrier gas stream through the column 19, but the temperature of the column 19 is lower than the boiling point of the low-boiling components, so the component to be measured is the column 19 Liquefied and retained while passing through. On the other hand, the solvent component is advanced by the carrier gas. At this time, since the flow path switching valve 1 is connected to the discharge flow path 15 from the column 19, the solvent that has passed through the column 19 is discharged from the discharge flow path. 15 is discharged out of the flow path. It is discharged from the column 19 through the discharge flow path 15 to the outside. At this time, the carrier gas from the carrier gas flow path 2 flows into the detector through the separation column 20.

During this time, the effluent components from the column 19 do not enter the separation column 20 and are all discharged. Since the injected sample is temporally separated into a solvent and other components in the process of passing through the column 18 and the column 19, a predetermined amount of the sample is injected into the column 18 and then a predetermined time In the meantime, if it is discharged from the discharge channel 15, almost all of the solvent component is discharged. When a predetermined time has elapsed after the sample injection and most of the solvent has been discharged, the temperature of the column oven 21 is raised and the temperature is increased according to a predetermined temperature program, as shown in FIG. 2 (c). Then, the flow path switching mechanism 1 is switched to switch the flow path from the column 19 to the flow path to the separation column 20.

When the heating of the oven is started, the target components held on the inner wall of the column 18 and the tip of the column 19 are sequentially evaporated from the low boiling point and are carried on the carrier gas. Then, it is fed into the separation column 20 through the flow path switching valve 1. While passing through the separation column 20, each target component is clearly separated according to the boiling point, reaches the detector 22, and is detected.

At this time, the types of columns 18, 19, and 20 and conditions such as column holding force, carrier gas flow rate, column oven temperature rise profile, and the like are appropriate depending on the type of solvent and the type of component to be measured. Used.

In addition, hardly volatile components contained in the original sample may remain near the inlet of the column 18 or 19 until the end, causing contamination. When a large amount of sample is introduced, the amount of sample introduced per analysis is large, so the amount of contamination-causing substances is also large. Exchange columns 18 and 19 or cut the vicinity of the inlet. It is necessary to frequently perform maintenance of contaminated parts.

The operation during maintenance is as follows. When the maintenance of the columns 18 and 19 is performed, the flow path switching valve 1 is connected so that the flow path from the column 19 is connected to the discharge flow path 15 and the carrier gas flow path 2 is connected to the separation column 20. At this time, the carrier gas is supplied to the separation column 20, and even if the detector 22 side is in a vacuum, the separation column 20 does not enter the atmosphere and deteriorate. In this state, the columns 18 and 19 can be exchanged, or the vicinity of the inlet can be cut to perform maintenance of the contaminated portion. Therefore, it is not necessary to stop the detector vacuum during maintenance. After the maintenance is completed and the columns 18 and 19 are connected to the original state, the flow path switching valve 1 is switched again so that the flow path from the column 19 is transferred to the separation column 20 and the carrier gas flow path 2 is discharged to the discharge flow path 15. To prepare for the next sample introduction.

In the present embodiment, the column is configured to use three different types of columns. However, the present invention is not limited to this, and may be selected depending on the component to be measured, and the same type of column may be used. Two or more can be used. Further, although the flow path switching valve is provided between the columns 19 and 20, it may be provided at any position in the middle of the column. For example, it may be provided between the columns 18 and 19, and when a large number of columns are connected, it may be provided at any connecting portion, and preferably provided at the upper end portion of the separation column. The above embodiment is merely an example, and it is apparent that changes and modifications can be made as appropriate within the scope of the present invention.

Moreover, although the present Example showed about the case where the on-column method was used as a mass sample introduction | transduction method, you may provide a flow-path switching valve in any part in the middle of the column of PTV method.

GC channel configuration diagram in one embodiment of the present invention Flow path switching valve used in one embodiment of the present invention GC channel diagram using conventional on-column method GC channel diagram using the conventional PTV method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Channel switching valve 2 ... Carrier gas channel 10 ... Sample introduction part 11 ... Carrier gas introduction part 13 ... Septum 14 ... Three-way joint 15 ... Discharge path 16 ..Valve 17 ... Laser light source 18 ... Precolumn 19 ... Precolumn 20 ... Capillary column 21 ... Column oven 22 ... Detector 23 ... Syringe 31 ... Filler 32 ..Split valve 33 ... Split flow path

Claims (1)

A gas chromatograph apparatus having a sample introduction section capable of introducing a large amount of sample, a column section communicating with the sample introduction section, and a flow path switching valve in the middle of the column section, wherein the flow path switching valve is located upstream of the valve Connect the flow path from the column to the column downstream of the valve, connect the flow path from the carrier gas flow path to the discharge port, and connect the flow path from the column upstream of the valve to the discharge port. A gas chromatograph apparatus characterized in that a flow path connecting a flow path from a path to a column downstream of a valve can be switched.

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