JPH0715460B2 - Concentration vaporization analyzer for gas phase samples by gas chromatography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention heats a sample containing a trace amount of organic matter to volatilize an organic gas (gas phase sample), concentrates the organic gas to a high concentration, and then uses the curie. Quickly heat to temperature to volatilize,
The present invention relates to a concentrated vaporization analyzer for a gas-phase sample by a gas chromatograph which prevents diffusion and is introduced into a capillary column of a gas chromatograph for analysis.

<Prior Art> A capillary tube having one end connected to a sample heating tube is passed through a U-shaped tube provided in a dewar bin, and the other end of the tube exiting from the U-shaped tube is wound into a coil to form a capillary column. A heater for heating is wound around the outer periphery of the character tube, and liquid nitrogen for cooling is filled in the dewar bin.
A gas chromatograph apparatus which is immersed in liquid nitrogen except for both ends of a U-shaped tube is known from JP-A-62-22061. This apparatus puts a sample into a sample heating tube, raises the temperature of the sample heating tube while flowing a carrier gas into the tube, and sends the volatile components in the sample to the capillary tube with the carrier gas,
At the U-tube penetrating portion of the tube, liquid nitrogen was used to cool to a low temperature to coagulate and concentrate, and then liquid nitrogen was discharged from the Dewabin, and then a heater was energized to rapidly heat the capillary tube to rapidly collect the coagulated and concentrated volatile components. It is vaporized and injected into a capillary column with a carrier gas for separation and analysis.

<Problems to be Solved by the Invention> In the above-mentioned conventional apparatus, since the penetrating portion of the capillary tube penetrating the U-shaped tube in the Dewabin is directly cooled by the liquid nitrogen filled in the Dewabin, the tube is overcooled and then the heater is used. It takes a long time to heat and vaporize,
At the stage of introducing the vaporized volatile component into the capillary column, the peak broadens and the detection sensitivity of the volatile component decreases.
Also, from the sample heating tube to the cooled U of the capillary tube
The volatile components fed into the pipe penetrating portion are concentrated to the highest concentration on the inlet side of the U pipe penetrating portion. Therefore, in order to heat the U-tube penetrating portion with a heater and vaporize the concentrated volatile components and then to feed them into the capillary column with carrier gas,
The vaporized volatile component must be moved in the forward direction from the inlet side to the outlet side of the U-shaped tube. At that time, the peak spreads because it diffuses in the tube, and the detection sensitivity of the volatile component decreases. To do.

Furthermore, when heating the U-tube penetrating portion of the capillary tube with a heater, it is necessary to discharge the liquefied nitrogen filled in the dewar bin in order to accelerate the heating, which requires time and labor.

<Means for Solving the Problems> The present invention is for solving the above-mentioned problems, and includes an inlet pipe for a carrier gas, a heating device for heating a sample containing an organic substance to volatilize an organic gas, and a volatilized organic substance. A vaporization chamber provided with a gas outlet pipe and an adsorption pipe are surrounded by a ferromagnetic metal foil, and the outside is surrounded by a cooling pipe through which cooling nitrogen gas passes, and a high frequency induction heating coil is wound outside the cooling pipe. A concentrated vaporization chamber, a gas chromatograph having a capillary column and an inlet port for organic gas to the capillary column, and a switching valve that selectively connects one end of the adsorption tube to the outlet port of the vaporization chamber and the inlet port of the gas chromatograph. When the switching valve makes one end of the adsorption pipe communicate with the inlet of the gas chromatograph, the outlet pipe of the vaporization chamber communicates with the other end of the adsorption pipe by a communication pipe. And

<Example> In the illustrated example, 1 is a container 2 and a heater 3 inside.
And a vaporization chamber 4 having a vaporization chamber, and 5 a capillary column of a gas chromatograph for separation, which has an inlet 16. The condensing vaporization chamber 4 is an adsorbent (for example, AKZO Reseach
Laboratories: Trade name Tenax GC) 1.6φ diameter
The outer circumference of the adsorption tube 6 filled in a 40 mm glass capillary is a ferromagnetic metal foil 7 with a thickness of about 50 μ (trade name: pyrofoil:
Enclosed with a cooling pipe 8 in which a very low temperature inert gas for cooling (eg, nitrogen gas at -100 ° C.) circulates, and a high frequency wave is placed outside the cooling pipe 8. The induction heating coil 9 is wound, and a high frequency power source 10 for induction heating and a timer 11 for controlling the induction heating time are provided.

Further, a vaporization chamber outlet pipe 1b for introducing a volatile component from the vaporization chamber 1 to the adsorption pipe 6 and a preheating pipe 12 at one end side 6a of the adsorption pipe are provided, and a preheating pipe 12 at one end side of the adsorption pipe is provided. A silicon diaphragm 13a for connecting to the adsorption tube 6 is provided at the tip.

On the other hand, the other end of the adsorption tube 6 is provided with a silicon diaphragm 13b for connecting to the communication tube 14.

Reference numeral 15 is a switching valve for selectively communicating one end 6a of the adsorption pipe with the outlet pipe 1b of the vaporization chamber and the inlet 16 of the gas chromatograph,
When one end 6a of the adsorption pipe is connected to the inlet 16 of the gas chromatograph, the outlet pipe 1b of the vaporization chamber is shown as shown by the solid line in FIG.
Is connected to the other end 6b of the adsorption pipe by a connecting pipe 14, and one end 6a of the adsorption pipe is connected.
Is connected to the outlet pipe 1b of the vaporization chamber, the inlet 16 of the gas chromatograph communicates with the connecting pipe 14 as shown by the broken line in FIG.

Further, a heater 17 is provided at one end side 6a of the adsorption tube 6 and at the preceding stage of the sample introduction port 16 of the gas chromatograph.

In the above apparatus, the sample containing a trace amount of organic matter is vaporized in the vaporization chamber 1
The container 2 is heated and vaporized, the carrier gas is introduced into the vaporization chamber 1 through the inlet 1a, and the switching valve 15 is operated to communicate the outlet pipe 1b of the vaporization chamber with the one end side 6a of the adsorption pipe. Then, the gas phase sample of the organic gas is carried to the carrier gas and guided to the adsorption tube 6. Since the adsorption tube is cooled to about -100 ° C by the -100 ° C nitrogen gas flowing in the cooling tube 8 surrounding it, the gas phase sample is adsorbed by the adsorbent filled in the adsorption tube, By continuing for a certain period of time, the gas phase sample is concentrated in the adsorbent. This concentration is highest at one end 6'of the adsorbent.

When the adsorption and concentration steps are completed, the flow of nitrogen gas into the cooling pipe is stopped, the switching valve 15 is operated, and one end 6a of the adsorption pipe is connected to the inlet 16 of the gas chromatograph. As a result, the outlet pipe 1b of the vaporization chamber is connected to the other end 6b of the adsorption pipe by the communication pipe 14. Then, the preset time is controlled by the timer 11 to energize the high frequency induction heating coil 9 from the high frequency power supply 10. Then, the ferromagnetic metal foil 7 surrounding the adsorption tube generates heat to the Curie temperature (235 ° C. in the case of the above-mentioned Pyro foil manufactured by Nippon Analytical Industry Co., Ltd.) in about 0.2 seconds by high frequency induction heating, and is adsorbed on the adsorbent in the adsorption tube. The concentrated gas phase sample is rapidly volatilized and desorbed from the adsorbent, and the gas phase sample volatilized by the carrier gas blown into the adsorption tube from the other end is conveyed to the capillary column 5 through the inlet 16 of the gas chromatograph and Perform separation analysis with ゝ.

In the above-described embodiment, the adsorption tube is filled with the adsorbent and the gas phase sample is adsorbed and concentrated on the adsorbent, but the adsorption tube may be not filled and the gas phase sample may be adsorbed and concentrated on the wall surface of the adsorption tube. When the adsorbent is filled, it is preferable to select and use an optimum material according to the type of organic substance contained in the gas phase sample.

Further, the Curie temperature of the ferromagnetic metal foil is a physical constant determined by the ratio of iron, nickel, cobalt, copper, etc. In this example, the Curie temperature of 235 ° C. was used. What has a temperature may be used.
It is preferable to use a ferromagnetic metal foil having a small heat capacity so that it is cooled immediately after the induction heating is finished, which can shorten the analysis time.

<Effect of the Invention> In the present invention, when the sample is heated and vaporized in the vaporization chamber, one end of the adsorption pipe is communicated with the outlet pipe of the vaporization chamber by the switching valve, and thereby vaporized by the carrier gas introduced into the vaporization chamber. The gas phase sample is put into an adsorption tube cooled to an extremely low temperature from one end, and is adsorbed and concentrated to the highest concentration at one end in the adsorption tube. When the adsorption process is completed, the switching valve is switched to connect one end of the adsorption pipe to the inlet of the gas chromatograph and the outlet pipe of the vaporization chamber to the other end of the adsorption pipe via the communication pipe.
The ferromagnetic metal foil that surrounds the adsorption tube is instantly heated to the Curie temperature by the high-frequency induction heating coil, the vapor-phase sample adsorbed and concentrated in one end of the adsorption tube is volatilized, and the carrier gas blown from the other end into the adsorption tube is used. The volatilized vapor phase sample is immediately transferred to the gas chromatograph. The gas phase sample thus concentrated to the highest concentration at one end in the adsorption tube is fed to the gas chromatograph in the opposite direction to that when it came into the adsorption tube. Therefore, the recovery efficiency of the concentrated gas phase sample is high, the gas phase sample does not diffuse because it does not move in the adsorption tube for a long time, the peak of the gas chromatogram is sharp, and the detection sensitivity of the volatile component is improved. Fig. 2 shows that an organic gas containing saturated hydrocarbons and aromatic compounds is adsorbed and concentrated in an adsorption tube, volatilized by heating with a nichrome wire, and the carrier gas moves the inside of the adsorption tube from one end to the other to send it to a capillary column. It is a gas chromatogram obtained by putting in, because the adsorption tube cannot be heated rapidly due to heating with nichrome wire, the temperature control is difficult, and diffusion occurs because the adsorption tube is moved from one end to the other. The peak of the gas phase component spreads and the detection sensitivity is low. On the other hand, when the same organic gas is separated and analyzed by the apparatus of the present invention, the gas chromatogram of FIG. 3 is obtained. In the gas chromatogram of FIG. 3, the peaks of each component are clearly distinguished and the detection sensitivity is remarkably excellent.

Further, since the cooling by the cooling tube is performed with an inert gas, when the high frequency induction heating coil is energized to heat the ferromagnetic metal foil to the Curie temperature and the adsorption-concentrated gas phase sample is volatilized,
Since it is only necessary to stop the inert gas from flowing into the cooling pipe, the operation is less time-consuming and more time-consuming than discharging the liquefied nitrogen.

Further, the concentrating vaporization chamber is composed of a ferromagnetic metal foil surrounding the adsorption tube, a cooling tube surrounding the adsorption tube, and a high-frequency induction heating coil wound around the adsorption tube, so the adsorption tube can be easily replaced with a new one. , The analysis accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a gas chromatogram by a conventional apparatus, and FIG. 3 is a gas chromatogram by the apparatus of the present invention of the same gas phase sample as in FIG. In the figure, 1 is a vaporization chamber, 1a is an inlet pipe of the vaporization chamber, 1b is an outlet pipe of the vaporization chamber, 2 is a container, 3 is a heater, 4 is a concentrated vaporization chamber, 5 is a capillary column, 6 is an adsorption tube, and 6a is an adsorption tube. One end of the tube,
6b is the other end of the adsorption tube, 6'is one end of the adsorption body, 7 is a ferromagnetic metal foil, 8 is a cooling tube, 9 is a high frequency induction heating coil, 10 is a high frequency power supply, 11 is a timer, 14 is a connecting tube, 15 is a switching valve,
Reference numeral 16 indicates an inlet of the gas chromatograph.

Claims (1)

[Claims] 1. A vaporization chamber having a carrier gas inlet tube, a heating device for heating a sample containing an organic substance to volatilize the organic gas, and an outlet tube for the volatilized organic gas, and an adsorption tube made of a ferromagnetic metal foil. Along with the surrounding, surrounded by a cooling pipe through which an inert gas for cooling passes, a concentrated vaporization chamber arranged by winding a high frequency induction heating coil outside the cooling pipe, and a capillary column,
And a gas chromatograph having an inlet port for organic gas to the capillary column, and an outlet pipe of the vaporization chamber at one end of the adsorption pipe, and a switching valve that selectively communicates with the inlet port of the gas chromatograph, the switching valve adsorbing Concentration vaporization analysis of gas phase sample by gas chromatograph characterized in that when one end of the tube is connected to the inlet of the gas chromatograph, the outlet tube of the vaporization chamber is connected to the other end of the adsorption tube by a connecting tube. apparatus.