JP3767115B2 - Gas chromatograph - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas chromatograph. More specifically, a detector having a burner that interacts with the column outflow gas and a detection unit that detects a physicochemical change resulting from the interaction, such as a flame photometric detector (FPD), a flame ionization detector ( FID) and a gas chromatograph detector provided with a flame thermionic detector (FTD).
[0002]
[Prior art]
A detector that has a burner that interacts with the column effluent gas and a detection unit that detects a physicochemical change that occurs as a result of the interaction exhibits a constant response when the burner and the detection unit are in a certain positional relationship. Yes, when the positional relationship between the burner and the detection unit cannot be maintained correctly, the detection sensitivity changes, and in an extreme case, there is no response.
[0003]
A conventional detector will be described using an FPD as an example. FIG. 5 is an explanatory diagram of a conventional FPD detector. The carrier gas flowing out from the column outlet end 4 is mixed with the hydrogen gas from the hydrogen gas regulator 5 and the air from the air regulator 6 and burns out from the nozzle 7 to become a flame 8. When sulfur or phosphorus compounds are contained in the carrier gas, the photomultiplier 9 receives light of a specific wavelength emitted from these compounds in a hydrogen flame through the quartz window 10 and the interference filter, and responds to these compounds. Become. Reference numeral 13 denotes an exhaust passage, and the inner diameter of the pipe is fixed.
[0004]
[Problems to be solved by the invention]
The flame 8 is maintained at a constant position and state by the balance of the carrier gas, hydrogen gas, and air (combustion gas), and if the flow rate of the carrier gas varies, the position and state of the flame 8 are changed. Change.
[0005]
Gas chromatographic analysis may be performed with the pressure of the carrier gas supplied to the column constant, and after performing a series of analyzes with the optimal hydrogen gas and air supply amount, the carrier gas flow rate is changed to To perform a series of analyses, it is necessary to adjust the hydrogen gas regulator 5 and the air regulator 6 in FIG. 5 to adjust the amount of gas of the three parties including the carrier gas to obtain an appropriate flame. was there.
[0006]
Furthermore, the column state may change during a series of analyzes over a long period of time, and in this case as well, it was necessary to individually adjust the hydrogen gas amount and the air amount separately as described above.
[0007]
Gas chromatographic analysis may be performed with a constant carrier gas flow rate supplied to the column. The carrier gas flow rate is optimally adjusted, and the hydrogen gas and air flow rates suitable for the carrier gas amount are adjusted. When the supply amount is set, the flame formation position may not be appropriate. An example of such a case will be described with reference to FIG.
[0008]
FIG. 6 is a schematic diagram when the position of the flame is not appropriate. The flame 8 is located away from the nozzle 7 and is at a position away from the quartz window 10 of the photomultiplier 9. In this case, even if the sulfur or phosphorus compound emits light of a specific wavelength in the flame 8, the light does not reach the photo 9. For this reason, since the sensitivity of the FPD is reduced, the flame 8 must be moved downward.
[0009]
Thus, when the flame formation position was inappropriate, it was necessary to return to the determination of the flow rate of the carrier gas and reset the flow rate of the three parties. For this purpose, it has been necessary to adjust the hydrogen gas regulator 5 and the air regulator 6 in FIG. 5 to adjust the three gases including the carrier gas.
[0010]
As described above, in the case of FPD, there are similar problems with flame adjustment in FID and FTD, and gas chromatographs equipped with these detectors include both hydrogen and air in some cases including carrier gas. Had to adjust the flow rate.
[0011]
An object of the present invention is to provide a gas chromatograph capable of adjusting the position and state of such a flame as easily as possible.
[0012]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a gas chromatograph including a burner that interacts with a gas flowing out from a column and a detector that has a detector that detects a physicochemical change resulting from the interaction. It features a throttle valve in the exhaust pipe of the vessel.
[0013]
Conventionally, when a throttle valve is provided in the exhaust pipe of a detector that has been open to atmospheric pressure with a fixed and fixed opening, the supply amount of hydrogen gas and air supplied to the detector adjusts the degree of opening and closing of the throttle valve. Is possible. Further, if a throttle valve is provided in the exhaust pipe of the detector, the pressure inside the detector can be adjusted by adjusting the opening / closing degree of the throttle valve.
[0014]
For this reason, the state and position of the flame can be adjusted by adjusting the opening / closing degree of the throttle valve.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, this invention is not limited to a following example.
[0016]
FIG. 1 is an explanatory diagram of a gas chromatograph equipped with an FPD according to the present invention. The carrier gas is controlled by one carrier gas regulator. When analyzing at a constant pressure, the carrier gas regulator 1 uses a pressure regulator, and when analyzing at a constant flow rate, a mass flow controller is used. 2 is a sample introduction port, 3 is a column.
[0017]
The carrier gas that has passed through the column enters the FPD from the column outlet end 4 and joins the hydrogen gas and air. 5 is a hydrogen gas regulator, and 6 is an air regulator, both of which are pressure regulators. These mixed gases form a flame 8 above the nozzle 7. 9 is a photomultiplier, and light emitted from sulfur or phosphorus compounds contained in the component band in the carrier gas passes through the quartz window 10 and the interference filter 11 to reach the photomultiplier 9 and is converted into an electric signal. Reference numeral 12 denotes a cooling fin.
[0018]
A throttle valve 14 is provided in the exhaust passage 13.
[0019]
When analyzing at a constant pressure, adjust the throttle valve 14 and adjust the outlet flow rate to change the overall flow rate ratio including the carrier gas while maintaining the optimal flow rate ratio between hydrogen gas and air. Can be made.
[0020]
Further, when analyzing at a constant flow rate, the flame formation position can be moved up and down only by opening and closing the throttle valve while keeping the flow rate ratio of hydrogen gas and air at the optimum ratio. For example, if the throttle valve is closed, the flame position moves downward.
[0021]
Subsequently, a specific example of the throttle valve 14 will be described.
[0022]
FIG. 2 is a cross-sectional view of one embodiment of the throttle valve. The outlet end of the exhaust passage 13 is tapered to form a throttle portion 22, and further, an inner peripheral portion is threaded. Reference numeral 21 denotes a hollow plug having a threaded outer periphery, and usually the tip is in contact with the throttle portion 22. The exhaust of the detector passes through the hollow portion of the hollow plug 21 and is released to the atmosphere. However, when the hollow plug 21 is rotated and pushed into the upstream side of the exhaust flow channel, the tip of the hollow portion is narrowed, and the flow resistance is increased. The pressure inside the detector increases. FIG. 3 is a plan view of the hollow stopper 21.
[0023]
FIG. 4 is a cross-sectional view of another embodiment of the throttle valve. A hollow rubber 23 is disposed at the tip of the hollow plug 21 of FIG. If the throttle valve of this embodiment is used, the throttle portion can be made into a smaller hole, so that a more delicate flow rate or pressure can be adjusted.
[0024]
【The invention's effect】
In the chromatograph of the present invention, the flow rate of the carrier gas passing through the column can be adjusted while keeping the mixing ratio of the flame hydrogen gas and air optimal, so that it is easy to set conditions for chromatographic analysis.
[0025]
In addition, when analyzing at a constant flow rate, the flame formation position can be moved up and down simply by opening and closing the throttle valve while keeping the flow rate ratio of hydrogen gas and air at the optimum ratio. Air flow adjustment is easy and labor saving is achieved.
[0026]
Furthermore, it becomes easy to keep the flame at the optimum position with respect to the detection unit, and the detection sensitivity of the detector can be improved.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a gas chromatograph equipped with an FPD according to the present invention.
FIG. 2 is a cross-sectional view of one embodiment of a throttle valve.
FIG. 3 is a plan view of the hollow stopper 21. FIG.
FIG. 4 is a cross-sectional view of another embodiment of a throttle valve.
FIG. 5 is an explanatory diagram of a conventional FPD detector.
FIG. 6 is a schematic diagram when the position of the flame changes.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Carrier gas regulator 2 Sample inlet 3 Column 4 Column outlet end 5 Hydrogen gas regulator 6 Air regulator 7 Nozzle 8 Flame 9 Photo 10 Quartz window 11 Interference filter 12 Cooling fin 13 Exhaust flow path 14 Throttle valve 21 Hollow plug 22 Diaphragm 23 rubber

Claims (1)

  A gas chromatograph equipped with a burner that interacts with the gas flowing out from the column and a flame photometric detector that detects physicochemical changes resulting from the interaction, is characterized in that a throttle valve is provided in the exhaust pipe of the detector. Gas chromatograph.

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