JP2000249693A - Gas chromatograph apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce scattering of a sample gas resulting from a temporary pressure increase due to the evaporation at the time of injecting a sample. SOLUTION: A pressure sensor 12 for monitoring a pressure of a sample evaporation chamber 11 and a temperature sensor 16 for monitoring a temperature are simultaneously monitored. Whether a pressure increase is caused by disturbances or injecting a sample is judged by monitoring if a temperature drop is brought about at the same time with the pressure increase. When the pressure increase is caused by the sample injection, a control part 15 slows a valve response to reduce an amount of a sample gas discharged from a split passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph, and more particularly, to a sample vaporized in a sample vaporization chamber, in which a portion of the sample is discharged through a split channel, and a portion of the sample is sent to a column for analysis. The present invention relates to a split-type gas chromatograph device that performs the following.

[0002]

2. Description of the Related Art In a sample introduction system of a gas chromatograph, a split system may be adopted. In this method, analysis is performed while adjusting the pressure in the sample vaporization chamber to be constant while discharging a part of the sample and the carrier gas through a channel other than the column.

FIG. 1 is a schematic structural view of a conventional split type gas chromatograph apparatus. The sample vaporization chamber 11 provided at the entrance of the column 14 has a carrier gas flow path for introducing a carrier gas and a purge flow for discharging components generated by a septum (silicon rubber cap) in the sample vaporization chamber 11. A path and a split flow path for discharging a part of the sample injected into the sample vaporizing chamber 11 together with the carrier gas are connected. A mass flow controller 10 for controlling the flow rate of a carrier gas such as He gas is provided in the carrier gas flow path. The mass flow controller 10 includes a flow rate sensor 21 and a valve 22 for controlling the flow rate, and functions to monitor the flow rate with the flow rate sensor 21 and perform feedback control of the valve 22 so that the flow rate becomes a set flow rate. Further, a pressure sensor 12 is provided in the purge passage. Since the pressure sensor 12 and the sample vaporization chamber 11 are connected so that there is almost no gas resistance, it can be treated as substantially the same as the gas pressure in the sample vaporization chamber 11. Pressure sensor 12
Is input to the control unit 15, and the control unit 15 performs feedback control of the control valve 13 provided in the split flow path so that the gas pressure becomes constant. The controller 15 controls the mass flow controller 10 so as to keep the ratio of the gas flowing in the split flow path and the column 14 (referred to as a split ratio, for example, to set the column 1: the split flow path 20 to approximately 20), thereby evaporating the sample. The flow rate of the carrier gas flowing into the chamber 11 is also adjusted. Note that a buffer 24 for responding to a sudden pressure change is provided in the purge flow path and the split flow path.

[0004]

In the above configuration, when a liquid sample is injected by a syringe inserted through a septum in the upper part of the sample vaporizing chamber, the sample is vaporized immediately after that, and the volume of the sample is increased. Rises sharply, and the pressure inside the sample vaporization chamber rises. The controller determines that such a fluctuation is a disturbance, and increases the amount of discharge by increasing the opening of the control valve in the split flow path to reduce the pressure in the sample vaporization chamber, and performs feedback control to maintain the pressure constant. work. In other words, the sample injected and vaporized to keep the pressure in the sample vaporization chamber constant is released more than necessary, and the amount of the sample introduced into the column is reduced. On the other hand, it is conceivable to set a slow response in the control unit in order to reduce the dissipation of the vaporized sample due to a rapid pressure rise during vaporization. However, if such a setting is made, the response will be slow even for disturbances other than during normal control or sample injection, which will cause trouble.

Accordingly, an object of the present invention is to provide a gas chromatograph apparatus having a sample vaporization chamber capable of suppressing dissipation of a vaporized sample during vaporization.

[0006]

A gas chromatograph apparatus according to the present invention, which has been made to solve the above-mentioned problems, has a structure in which a sample vaporized in a sample vaporization chamber is partially discharged through a split flow path. In a split-type gas chromatograph apparatus that sends a gas to a column, a control valve that controls the discharge amount of the split flow path, a pressure sensor that monitors the gas pressure in the sample vaporization chamber, and a temperature sensor that monitors the gas temperature in the sample vaporization chamber And control means for controlling a control valve of the split flow path using information on the gas pressure and the gas temperature.

In the present invention, the pressure fluctuation in the sample vaporization chamber is monitored, and the temperature fluctuation in the sample vaporization chamber is also monitored. When the pressure sensor detects a change in pressure, it simultaneously monitors the magnitude of the temperature change at that time. If the temperature fluctuation is equal to or less than a predetermined set value, it is determined that the fluctuation is a pressure fluctuation due to disturbance, and normal quick feedback control is performed.
If the temperature fluctuation is equal to or higher than a predetermined set value, it is determined that the fluctuation is not a disturbance but a fluctuation due to the vaporization of the injected sample, and in this case, the response of the valve is not a quick control but a normal response. Perform the delayed control. This allows
The amount of dissipation at the time of vaporization can be reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 2 shows a gas chromatograph apparatus according to one embodiment of the present invention. In the figure, the same parts as those in FIG. The apparatus of this embodiment differs from the conventional gas chromatograph apparatus of FIG. 1 in that a temperature sensor 16 for monitoring the temperature of the gas in the sample vaporization chamber 11 is provided in the purge flow path. is there. The temperature sensor 16 may be mounted at any position as long as the gas temperature in the sample vaporization chamber can be substantially measured. However, if the temperature sensor 16 is mounted on the purge flow path, only the carrier gas flows, so that the sample is less contaminated. There is an advantage. Although the sample gas is not allowed to flow into the purge flow path, it is possible to detect that the sample has been vaporized by detecting a decrease in the carrier gas temperature due to heat of vaporization caused by vaporization of the sample. The detection signal output from the temperature sensor 16 is input to the control unit 15. In addition, since the flow resistance of the purge flow path is larger than that of the split flow path (a resistance tube (not shown) is provided on the downstream side), the flow rate fluctuation of the gas flowing through the purge flow path is small, No control valve is provided. Next, the operation of this device will be described. First, the flow sensor 2 of the mass flow controller 10
By controlling the valve 22 while monitoring the carrier gas flow rate in step 1, feedback control is performed so that a constant flow rate of the carrier gas is introduced into the sample vaporization chamber 11. The control valve 13 in the split flow path controls the pressure in the sample vaporization chamber to be set. This allows the carrier gas to flow at a constant split ratio between the column side and the split channel side while maintaining the sample vaporization chamber at a constant pressure. At this time, the gas temperature in the sample vaporization chamber 11 is monitored by the temperature sensor 16 at the same time.

The operation of the control unit 15 will be described with reference to the flowchart of FIG. The signal from the pressure sensor 12 is sent to the control unit 15, and the momentary pressure fluctuation of the sample vaporization chamber 11 is monitored. When the control unit 15 determines that the pressure fluctuation is within a predetermined set fluctuation range, normal control is performed so that the valve 13 responds quickly to the pressure fluctuation. When the control unit 15 recognizes that the pressure detection signal fluctuates more than a predetermined fluctuation range for some reason, the temperature fluctuation at that time is examined. If it is determined that the temperature fluctuation is within a predetermined set fluctuation range, the control unit 15 determines that the pressure fluctuation at this time is a fluctuation due to a disturbance, and the valve 13 continues normal quick control as it is. I do. On the other hand, if the controller 15 recognizes that the pressure signal fluctuates more than the predetermined set fluctuation range, and further recognizes that the temperature fluctuation also exceeds the set fluctuation range, the control unit 15 injects the sample and evaporates. Then, the control of the valve 13 is changed. That is, the setting is changed so that the valve 13 responds slowly to the pressure fluctuation, and the response to the pressure fluctuation becomes slow. Therefore, the pressure increases sharply at the same time as the injection of the sample.
3 is set to be slow, the control valve 13
Since the opening degree does not fluctuate easily and the flow rate discharged to the split flow path does not increase, the amount of the sample gas dissipated into the split flow path decreases. Then, when the pressure returns to near the original state after a while, it is determined that the sample has been sent out from the inside of the sample vaporization chamber 11, and the control is returned to the normal control.

[0010]

As described above, in the gas chromatograph apparatus of the present invention, the sample vaporization chamber is controlled by monitoring the temperature as well as the pressure of the sample vaporization chamber. It is possible to determine whether the cause is due to the vaporization of the sample or a disturbance, and the response of the valve can be set optimally according to the result. Then, by reducing the dissipation of the sample, highly sensitive analysis can be performed, and accuracy in quantitative analysis can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional gas chromatograph apparatus.

FIG. 2 is a configuration diagram of a gas chromatograph apparatus according to one embodiment of the present invention.

FIG. 3 is a flowchart showing an example of an operation.

[Explanation of symbols]

 10: Mass flow controller 11: Sample vaporization chamber 12: Pressure sensor 13: Control valve 14: Column 15: Control unit 16: Temperature sensor 21: Flow sensor 22: Valve

Claims (1)

[Claims] 1. A split type gas chromatograph device which sends a sample vaporized in a sample vaporization chamber to a column while discharging a part of the sample through a split flow path,
A control valve for controlling the discharge amount of the split flow path, a pressure sensor for monitoring the gas pressure in the sample vaporization chamber, a temperature sensor for monitoring the gas temperature in the sample vaporization chamber, and using information on the gas pressure and the gas temperature. And a control means for controlling a control valve of the split flow path.