JP4377020B2 - Method and apparatus for analyzing components in headspace - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a headspace component analysis method and apparatus. More specifically, the present invention relates to an analysis method and apparatus for a headspace component, in which a component of a headspace in a container into which a sample is injected can be collected while maintaining a balance and then analyzed.
[0002]
[Prior art]
Conventionally, as a method for analyzing a gas phase component in a container into which a sample is injected, for example, a perfume and its aroma component, so-called dynamic method and static method are known. As shown in FIG. 6, the apparatus used for the dynamic method is usually configured as follows. The container 1 into which the sample has been injected is placed in a water bath 2 having a predetermined temperature, and a stirring bar 3 is provided in the sample or at the bottom of the water bath 2 so that the sample can be stirred as necessary. In the figure, symbol 9 is a stirrer. A column 5 filled with an adsorbent is installed at the top of the container 1 through a water-cooled tube 4. The container 1 is provided with an inert gas inlet 6 such as nitrogen gas. An inert gas is blown into the container, and the gas phase component together with the inert gas is passed through a cooling pipe to the column filled with the adsorbent, and the gas phase component is collected in the column, and the collected gas phase component is analyzed. Is the method. Because it is trying to forcibly move the gas phase component to the column side by blowing in inert gas, it tends to detect more low boiling point in the sample than the gas phase component originally present in the head space This method has the following disadvantages.
[0003]
In the static method, for example, a headspace gas phase is directly sampled with a gas tight syringe and injected into a gas chromatograph to analyze a headspace gas phase component, for example, a fiber in which an adsorbent is coated in the headspace gas phase. A solid phase micro-extraction method (SPME method; Japanese Patent Publication No. 5-506715) is well known in which a gas phase component is adsorbed by an adsorbent and injected into a gas chromatograph to analyze the gas phase component. . As shown in FIG. 7, the apparatus used for this SPME method usually has the following configuration. A fiber 7 coated with an adsorbent is inserted into a container 1 into which a sample placed in a water bath 2 is injected, and a gas phase component is adsorbed. This fiber 7 is accommodated in a hollow needle (not shown) of the syringe. After adsorption, the fiber is housed in a needle and the needle is connected to a gas chromatograph to analyze the adsorbed components. In this method, it is possible to measure the gas phase component while maintaining the balance as it is. However, since the fiber can be stored in the needle, the fiber must be thin. For this reason, the amount of adsorption is small, and therefore the amount is often insufficient for analysis of various types of aroma components.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to solve the above problems and to provide a method and an apparatus for analyzing a gas phase component in a head space in a container into which a sample is injected without losing the balance.
[0005]
[Means for Solving the Problems]
The present invention provides a method for analyzing a headspace component, which comprises the following steps a to d.
[0006]
a. loading a coating rod coated with an adsorbent into the headspace of a sealed container into which the sample has been injected;
b. A step of taking out the coating rod that has adsorbed the components in the head space from the sealed container and inserting it into the U-shaped tube from one end of the U-shaped tube equipped with heating means at least on the upper side,
c. After immersing at least the lower part of the U-tube with the coating rod in the refrigerant, heat the U-tube to desorb the components adsorbed on the coating rod, and place the desorbed components on the bottom of the U-tube. The process of accumulating,
d. A step of connecting the other end of the U-shaped tube taken out from the refrigerant to the sample inlet of the gas chromatograph and analyzing the components desorbed by the introduction of inert gas.
[0007]
The present invention further includes a coating rod provided with an adsorbent layer, a support tube for mounting the coating rod so as to be slidable in one of the U-shaped tubes, a support tube, and the support tube attached thereto. A headspace component comprising: an opening / closing member that allows the inside of the U-tube to be sealed with respect to the support tube between one end of the U-tube and a gas chromatograph connecting member at the other end of the U-tube An analysis apparatus is provided.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. FIG. 1 shows a coating rod 11 provided with an adsorbent layer 12. The coating rod is not limited to a metal rod such as a glass rod or a stainless steel rod, but may be a bundle of fibers. For example, it is formed from a fused silica fiber, a graphite fiber, a fiber made from a solid polymer material, a fiber made from a metal material, or the like. As the adsorbent used in the adsorbent layer, an appropriate adsorbent is selected and used according to the gas phase component.
[0009]
FIG. 2 shows an example of an apparatus for adsorbing a gas phase component on the adsorbent layer of the coating rod. The coating rod 11 is inserted into the head space of the container 1 into which the sample is injected, which is installed in the water bath 2, and the gas phase component is adsorbed on the adsorbent layer. The sample may be agitated as necessary by the agitator 3. The coating rod 11 that has adsorbed the gas phase component is charged into the U-shaped tube.
[0010]
The analyzer of the present invention including a U-shaped tube is shown in FIGS. The U-shaped tube 15 is provided with heating means 16 for desorbing the adsorbed gas phase component. The heating means 16 may be a nichrome wire wound around a U-shaped tube at an appropriate interval. At the end of the U-shaped tube on the side where the coating rod 11 is inserted, a support tube 13 for the coating rod 11 is provided through an opening / closing member 14 which can block the inside of the U-shaped tube from the outside air and allow the coating rod to slide. Is installed. A so-called ball valve is preferably used as the opening / closing member 14. With the ball valve 14 open, the coating rod 11 is inserted into the support tube 13 and the U-shaped tube 15. A handle 17 is preferably provided on the top of the coating rod 11 so that the inside of the support tube 13 can be blocked from the outside air when the coating rod 11 is completely loaded. An inert gas inlet 18 is provided near the opening / closing member 14 of the U-shaped tube 15. A gas chromatograph connecting member 19 communicating with the inside of the U-shaped tube 15 is provided on the other end side of the U-shaped tube 15.
[0011]
The lower part of the U-shaped tube 15 in which the coating rod 11 is inserted is installed in the refrigerant tank 20. As the refrigerant, an appropriate refrigerant is selected and used in accordance with a gas phase component such as liquid nitrogen or liquid oxygen. After installing in the refrigerant tank 20, it heats with the heating means 16, and desorb | desorbs a gaseous phase component from an adsorbent tank. The desorbed vapor phase component is cooled by the refrigerant and accumulates at the bottom of the U-shaped tube. An inert gas may be injected from the inert gas inlet 18 in order to promote desorption from the adsorbent tank and promote movement toward the bottom of the U-shaped tube. As the inert gas, an appropriate gas such as argon gas, helium gas or nitrogen gas is selectively used.
[0012]
After the desorption of the gas phase component, as shown in FIG. 4, the coating rod 11 is lifted above the opening / closing member 14 to close the opening / closing member, for example, the ball valve, and then removed from the refrigerant tank 20. A gas chromatograph connecting member 19 provided at the other end of the U-shaped tube 15 is connected to the gas chromatograph, an inert gas is injected from an inert gas inlet 20, and a gas phase component is fed into the gas chromatograph. Analyze ingredients.
[0013]
【Example】
Hereinafter, the present invention will be described in more detail based on examples.
[0014]
Example 1
Using the pulverized roasted coffee beans (Brazil), the gas phase component (fragrance) in the head space is collected by the method shown in FIG. 2, and the adsorbed components are shown in FIG. 3 and FIG. The adsorbed components were desorbed using and analyzed by gas chromatography. The analysis conditions are shown below.
Gas phase component collection condition Sample amount: 5.0 g
External temperature: 30 ° C
Collection time: 30 minutes Adsorbent: Tenax system desorption condition As shown in FIG. 3, the coating rod 11 is attached to the U-shaped tube, and the support tube 13 side and the U-shaped tube side are blocked by the ball valve 14, and then helium While feeding the gas, the heater was heated to 220 ° C., and the gas phase component adsorbed on the coating rod was accumulated at the bottom of the U-shaped tube cooled in the refrigerant tank. Thereafter, the coating rod 11 is moved to the position shown in FIG. 4, and the support tube side and the U-shaped tube side are similarly shut off by the ball valve 14. Then, the refrigerant tank 20 is removed, and then helium gas is sent to remove the gas phase component It injected into the gas chromatograph and analyzed.
Gas chromatograph conditions Gas chromatograph: Shimadzu GC-14A (manufactured by Shimadzu Corporation)
Column: TC-WAX 0.25MMI.D. × 60m
Column temperature: 70 ° C. to 220 ° C. (temperature rise of 3 ° C. per minute)
Carrier gas: Nitrogen detector: FID
[0015]
Comparative Example 1
Using ground roasted coffee beans (Brazil), the gas phase components in the head space were collected by the dynamic method shown in FIG. 6 , and the adsorbed components were analyzed by gas chromatography. Water was not passed through the catching water condenser. The analysis conditions are shown below.
Gas phase component collection conditions Sample amount: 1.0 g
External temperature: 30 ° C
Nitrogen gas flow rate: 50ml / min.
Adsorption time: 1 minute Adsorbent: Tenax TA
Gas Chromatograph Conditions The same gas chromatogram analyzed in Example 1 and Comparative Example 1 as in Example 1 is shown in FIG. Compared with the method of Comparative Example 1, the aromatic component of roasted coffee beans analyzed by the method and apparatus of the present invention could be analyzed up to a medium-high boiling point component.
[0016]
【The invention's effect】
According to the present invention, the gas phase components in the head space can be collected without breaking the balance, and an amount sufficient for the analysis of the gas phase components can be collected.
[Brief description of the drawings]
FIG. 1 shows a coating rod according to the present invention.
FIG. 2 is an explanatory view showing gas phase component adsorption according to the present invention.
FIG. 3 is an explanatory view showing a desorption mechanism for a coating rod adsorbing component.
FIG. 4 is an explanatory view showing a gas chromatograph feeding mechanism of a desorption component.
FIG. 5 is a drawing showing the results of gas chromatographic analysis in Examples and Comparative Examples.
FIG. 6 is an explanatory view showing an adsorption mechanism of a gas phase component by a dynamic method.
FIG. 7 is an explanatory view showing an adsorption mechanism of a gas phase component by a static method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Container 11 Coating rod 12 Adsorbent layer 13 Support pipe 14 Opening and closing member 15 U-shaped pipe 16 Heating means 17 Handle 18 Inert gas inlet 19 Gas chromatograph connection port 20 Refrigerant tank

Claims (4)

A headspace component analysis method comprising the following steps a to d:
a. loading a coating rod coated with an adsorbent into the headspace of a sealed container into which the sample has been injected;
b. A step of taking out the coating rod that has adsorbed the components in the head space from the sealed container and inserting it into the U-shaped tube from one end of the U-shaped tube equipped with heating means at least on the upper side,
c. After immersing at least the lower part of the U-tube with the coating rod in the refrigerant, heat the U-tube to desorb the components adsorbed on the coating rod, and place the desorbed components on the bottom of the U-tube. The process of accumulating,
d. The step of connecting the other end of the U-shaped tube taken out from the refrigerant to the sample inlet of the gas chromatograph and analyzing the components desorbed by the introduction of inert gas.   After the U-tube with the coating rod is immersed in the refrigerant, the U-tube is heated while feeding an inert gas, and the components adsorbed on the adsorbent layer are moved to the bottom side of the U-tube Item 4. A method for analyzing a headspace component according to Item 1.   A coating rod provided with an adsorbent layer, a support tube for mounting the coating rod so as to be slidable in one tube of the U-shaped tube, a support tube and a U-shaped tube to which the support tube is attached 1. A headspace component analyzing apparatus comprising: an opening / closing member capable of sealing the inside of a U-shaped tube with respect to a support tube between one end and a gas chromatograph connecting member at the other end of the U-shaped tube. Member freely sealing is a ball valve which can slide coating bars, when pulling the coating rod in the support tube, analysis equipment in the headspace component according to claim 3, characterized in that the closed state.

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