JP2000275230A - Gas chromatograph device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantatively detect leakage in a short time by opening a flow contol valve to pressurize the interior of a sample introducing part into fixed pressure, monitoring pressure variation, and computing the leakage flow in the flow passage from the data and displaying. SOLUTION: A control part 12 opens the flow control valve 5 of a carrier gas flow passage, and closes the flow controlvalve 5 when a pressure sensor 6 indicates a fixed pressurized value. From relation of the data of a flow sensor 11 and the opening/closing time of the flow control valve 5 and the pressure value of the pressure sensor 6, the inner volume of a gas flow passage is computed, and the computed result is displayed on a monitor screen 13. Next when the control part 12 closes the flow control valve 5, pressure is gradually lowered by leakage in a gas chromatograph device. Herefrom, a leakage flow is computed and displayed on the monitor screen 13. Pressure variation at every moment is made in graph, and by displaying it on the monitor screen 13, an analyzer is quantatively informed leakage quantiy in about 10 minutes, and can judge whether analysis is to be begun or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas chromatograph, and more particularly to a gas chromatograph for analyzing a sample vaporized in a sample vaporization chamber.

[0002]

2. Description of the Related Art In a sample analysis using a gas chromatograph, a sample is injected into a sample introduction portion, heated in the sample introduction portion, vaporized, and then analyzed together with a carrier gas sent from a carrier gas supply channel. Send to The sample is distributed between the liquid phase fixed on the inner surface of the analytical column and the carrier gas.The components in the sample are separated by the difference in the partition coefficient, and then introduced into the detection unit connected to the subsequent stage of the column. Detected as grams. The analyst confirms that there is no leak in the gas flow path of the gas chromatograph before starting the analysis in order to perform the above analysis accurately. That is, the amount of leakage in the gas flow channel was measured by introducing a carrier gas so that the inside of the flow channel of the gas chromatograph device became a constant pressurized state, and measuring the pressure drop after a lapse of a predetermined time. .

FIG. 1 shows the configuration of a conventional gas chromatograph apparatus. In the drawing, reference numeral 1 denotes a sample introduction unit, which is provided with a heater (not shown) on the wall surface, and by heating the heater, the sample gas introduced therein can be vaporized. The upper surface of the heating introduction unit is sealed with septum rubber. When introducing a sample, the septum rubber is injected by piercing the septum rubber with a needle of a syringe. An analysis column 2 is connected to the lower surface side of the sample introduction unit 1, and the other end of the analysis column 2 is connected to a detector 3. As the detector 3, a thermal conductivity detector, an FID detector, or the like is used according to the type of the sample. A carrier gas flow path C for supplying a carrier gas is connected to the sample introduction unit 1. The carrier gas flow path C is provided with a cylinder 4 as a high-pressure gas source and a flow control valve 5 for controlling a gas flow rate in the flow path.
The sample introduction unit 1 is further provided with a pressure sensor 6 for monitoring the internal pressure.

[0004] Next, the procedure of leak detection performed in this conventional apparatus will be described. If a leak exists in the gas flow path, accurate analysis cannot be performed. Therefore, the analyst confirms beforehand that there is no leak in the flow path before performing the analysis. A blind (stopper) is attached to the latter part of the analytical column. First, the flow control valve 5 is set so that the pressure of the sample introduction part 1 is in a pressurized state.
open. The pressure at this time is generally 500 kP
a. After being stabilized in this pressurized state, the flow control valve 5 is closed. After standing still in this state and after a predetermined time elapses, the output of the pressure sensor is measured, and if the pressure fluctuation around the elapse of the predetermined time is within an allowable range, it is determined that the leakage is small and does not hinder the analysis. To start the analysis. Generally, in this method, a change amount of about 10 kPa per hour is acceptable.

[0005]

In a conventional leak detection method, a pressure drop is measured after a certain time has elapsed after pressurization. Therefore, it is necessary to wait until a certain time elapses, a long time is required for detection, and it has been difficult to start analysis and make a quantitative judgment. Therefore, an object of the present invention is to provide a gas chromatograph analyzer capable of performing quantitative leak detection in a short time before the start of analysis.

[0006]

According to the present invention, there is provided a gas chromatograph apparatus wherein a sample gas vaporized in a sample introduction section is sent to a column together with a carrier gas supplied from a carrier gas flow path. After the provided flow control valve, the flow sensor provided in the carrier gas flow path, the pressure sensor for monitoring the gas pressure of the sample introduction section, and the flow control valve opened to pressurize the inside of the sample introduction section to a constant pressure. A control unit that closes the flow control valve and controls the subsequent pressure fluctuation of the sample introduction unit with a pressure sensor, a calculation unit that calculates a leakage flow rate of the flow path from the pressure fluctuation data, Display means for displaying data.

In the present invention, when leak detection is performed, the control unit opens the flow control valve in the carrier gas flow path, and opens the flow control valve until the pressure sensor reaches a constant pressure value P. At this time, the internal volume V in the gas chromatograph can be expressed as follows using the output f (ml / min) from the flow sensor. V = ∫fdt / P (1) By displaying this value on the monitor screen, the analyst can know the internal volume of the gas flow path of the gas chromatograph device. Next, when the control unit closes the control valve, the pressure gradually decreases due to a leak existing in the gas chromatograph device. The leakage flow rate at this time can be expressed as follows. f1 = dP / dt (2) Therefore, by displaying this value on the monitor screen, the amount of leakage can be known. Then, by displaying the fluctuation of pressure every moment as a graph with the horizontal axis representing time and the vertical axis representing pressure, the analyst can know the amount of leakage in a short time of about 10 minutes and start analysis. Can be determined.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 2 is a configuration diagram of a gas chromatograph apparatus according to one embodiment of the present invention. In the figure, the same parts as those in FIG. In this device, a flow sensor 11 is attached to a carrier gas flow path C as compared with the conventional example of FIG.
It receives signals from the pressure sensor 6 and the flow sensor 11 and controls the flow control valve 5 in the carrier gas flow path C,
Further, the difference is that a control unit 12 for controlling the display of the monitor screen 13 is provided. The flow control valve 5
Is such that the flow rate can be zero, that is, fully closed. Although a mass flow controller in which the flow control valve 5 and the flow sensor 11 are integrated may be used, the flow control valve and the flow sensor are only described separately for convenience of explanation.

Next, detection of leakage in this embodiment will be described. Prepare to attach a blind (stopper) to the subsequent stage of the analytical column 2. First, the control unit 12 opens the flow control valve 5 in the carrier gas flow path and waits until the pressure sensor 6 reaches a constant pressure value P (for example, 500 kPa). When the value of the pressure sensor becomes constant, the flow control valve 5 is closed. The internal volume of the gas flow path is calculated from the relationship between the data of the flow sensor 11 and the time from when the flow control valve 5 is opened to when it is closed, and the pressure value of the pressure sensor 6 using the equation (1). This calculation result is displayed on the monitor screen 13. Subsequently, when the control unit 12 closes the control valve 5, the pressure gradually decreases due to a leak existing in the gas chromatograph device. The leakage flow rate at this time is determined by equation (2). By displaying this value on the monitor screen 13, the amount of leakage can be known. Then, by displaying a graph in which the horizontal axis indicates time and the vertical axis indicates pressure with respect to momentary pressure fluctuation on the monitor screen 13, the analyst quantitatively knows the leakage amount in a short time of about 10 minutes. And determine whether to start the analysis. In addition,
In the above example, a blind was previously attached to the subsequent stage of the analytical column, but instead of attaching the blind,
It is also possible to determine the outflow flow rate from the column in advance and incorporate it into the calculation of the leakage amount. That is, since the measured flow rate is the sum of the outflow flow rate from the leak location and the outflow flow rate from the column, the amount obtained by subtracting the column outflow flow rate from the measured flow rate can be determined as the leak rate. In this method, the accuracy is lower than when the measurement is performed by closing the latter part of the column,
This eliminates the need to attach a blind to the column, and is effective for automating leak measurement. Hereinafter, embodiments will be summarized. (1) In a gas chromatograph apparatus in which a sample gas vaporized in a sample introduction section is sent to a column together with a carrier gas supplied from a carrier gas flow path,
A flow control valve provided in the carrier gas flow path, a flow sensor provided in the carrier gas flow path, a pressure sensor for monitoring the gas pressure of the sample introduction section, and a constant pressure inside the sample introduction section by opening the flow control valve. Close the flow control valve after pressurizing to, a control unit that performs control to monitor the pressure fluctuation of the subsequent sample introduction unit with a pressure sensor, and calculate the internal volume from the amount of carrier gas at the time of pressurization, A gas chromatograph apparatus comprising: a calculating means for calculating a leak flow rate of a flow path from data of pressure fluctuation; and a display means for displaying data on a leak flow rate. (2) In a gas chromatograph apparatus in which a sample gas vaporized in a sample introduction section is sent to a column together with a carrier gas supplied from a carrier gas flow path,
A flow control valve provided in the carrier gas flow path, a flow sensor provided in the carrier gas flow path, a pressure sensor for monitoring the gas pressure of the sample introduction section, and a constant pressure inside the sample introduction section by opening the flow control valve. Close the flow control valve after pressurizing to, a control unit that performs control to monitor the pressure fluctuation of the subsequent sample introduction unit with a pressure sensor, and calculate the internal volume from the amount of carrier gas at the time of pressurization, A gas chromatograph apparatus comprising: a calculating means for calculating a leakage flow rate of a flow path from data of pressure fluctuation; and a display means for displaying a time fluctuation of a pressure of a sample introduction part in a graph.

[0010]

As described above, the gas chromatograph of the present invention can quantitatively detect the internal volume and the amount of leakage from the relationship between the amount of introduced carrier gas and the pressure. In addition, since the amount of leakage can be known in a short time, the waiting time before the start of analysis can be reduced.

[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 diagram showing display contents of a monitor screen.

[Explanation of symbols]

 1: Sample introduction unit 2: Analysis column 3: Detection unit 5: Flow control valve 6: Pressure sensor 11: Flow sensor 12: Control unit 13: Monitor screen

Claims (1)

[Claims] In a gas chromatograph apparatus configured to send a sample gas vaporized in a sample introduction section to a column together with a carrier gas supplied from a carrier gas flow path, a flow control valve provided in the carrier gas flow path; A flow sensor provided in the carrier gas flow path, a pressure sensor that monitors the gas pressure of the sample introduction unit, and a flow control valve is opened to close the flow control valve after the inside of the sample introduction unit is pressurized to a constant pressure, A control unit that performs control for monitoring the pressure fluctuation of the sample introduction unit with a pressure sensor, a calculating unit that calculates a leakage flow rate of the flow path from the pressure fluctuation data, and a display unit that displays data related to the leakage flow rate. A gas chromatograph device comprising: