JP2742492B2 - Pyrolysis equipment for gas chromatography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyrolysis apparatus for pyrolysis gas chromatography, which is used to pyrolyze an analytical sample composed of a polymer resin or the like and subject it to gas chromatography.

[0002]

2. Description of the Related Art When analyzing a solid or liquid analytical sample made of a polymer resin or the like by gas chromatography, it is necessary to first thermally decompose and vaporize the analytical sample. Therefore, conventionally, as a pyrolysis apparatus for pyrolyzing and vaporizing the analysis sample, a pyrolysis apparatus for gas chromatography provided with a single heating means on the upstream side of a gas chromatography column is known.

In the pyrolysis apparatus, heating means for pyrolyzing and vaporizing the analysis sample is provided on an outer peripheral portion of a cylinder having one end connected to a gas chromatography column and the other end having an open end. Have been. In the apparatus, the analysis sample inserted into the cylinder from the open end is thermally decomposed by the heating means, and a vaporized component is sent to the gas chromatography column by a carrier gas introduced into the cylinder. It has become.

[0004] The analysis sample composed of the polymer resin or the like contains a low molecular component such as a plasticizer in addition to the polymer component serving as the base of the resin. It is desirable to clarify not only the composition of the high molecular component but also the composition of the low molecular component. However, in the conventional thermal decomposition apparatus, since the thermal decomposition of the analysis sample is performed at a temperature at which the high molecular component is thermally decomposed, the low molecular components are further pyrolyzed by the molecules themselves constituting the component, Causing a chemical reaction and altering,
There is an inconvenience that it is difficult to separate the low molecular components from each other.

[0005] In order to solve the above-mentioned inconvenience, before the polymer component of the analysis sample is thermally decomposed by the conventional pyrolysis apparatus, the heating means itself into which the analysis sample is inserted is subjected to two heating operations.
There has been proposed a thermal decomposition apparatus that is inserted into a heating block heated to 00 to 300 ° C. According to such a thermal decomposition apparatus, the analysis sample is first heated in the heating block, the low-molecular component is vaporized, and then the high-molecular component is thermally decomposed by performing heating by the heating means. The composition of the low molecular component can be analyzed with high accuracy without being thermally decomposed or deteriorated.

However, the high molecular component is held in the heating block together with the heating means and is exposed to the heating atmosphere until the analysis is completed after the low molecular component is vaporized. Undesirable reactions may occur, making accurate analysis difficult. Examples of the undesired reaction include a reaction in which, when air is mixed into the cylinder at the time of inserting a sample, the polymer component is exposed to the heating atmosphere and oxidized by oxygen in the air.

Japanese Unexamined Patent Publication (Kokai) No. 2-201156 discloses a single heating means in the conventional pyrolysis apparatus.
Disclosed is a gas chromatography pyrolysis apparatus separated into two heating means, a main heating means for thermally decomposing and vaporizing the analysis sample, and a sub-heating means for heating the analysis sample at a lower temperature than the main heating means. ing. The pyrolysis apparatus disclosed in the publication, one end is connected to the gas chromatography column, the other on the outer peripheral portion of the cylinder is an open end, provided with the main heating means on the gas chromatography column side, The auxiliary heating means is provided on the open end side. In the thermal decomposition device, the components vaporized by the main heating unit or the sub-heating unit are sent to the gas chromatography column by a carrier gas introduced into the cylinder.

[0008] The pyrolysis apparatus further includes a heating position of the analysis sample inserted from the open end of the cylinder, a heating position of the main heating means, a heating position of the sub-heating means, and any heating means in the cylinder. There is provided a sample moving means which can move between positions which are not heated even by the above.

In the above apparatus, the main heating means and the sub-heating means are operated simultaneously.
The analysis sample is inserted from the open end of the cylinder by the sample moving means and is held at a heating position by the sub-heating means.
Heat to ° C. Then, the low molecular components contained in the analysis sample are vaporized and sent to the gas chromatography column by the carrier gas, and the low molecular components are analyzed.

The analysis sample is moved by the sample moving means to a position where it is not heated by any heating means in the cylinder and waits until the low molecular component is vaporized and the analysis by gas chromatography is completed. I have. When the analysis of the low-molecular component is completed, the analysis sample is moved to the heating position by the main heating unit by the sample moving unit and held at this position. Then, the analysis sample is heated to 300 to 1000 ° C. by the main heating means to be thermally decomposed, and each vaporized component is sent to the gas chromatography column by the carrier gas.

According to the thermal decomposition apparatus, the analysis sample is heated in two stages as described above, and first, low-molecular components such as a plasticizer contained in the analysis sample composed of the high-molecular resin are vaporized, Next, since the polymer component serving as the base of the resin is thermally decomposed, it is expected that the low-molecule can be analyzed with high accuracy without being thermally decomposed or deteriorated. Further, while the low molecular component is being analyzed, the analysis sample is moved to a position where it is not heated by any heating means and is on standby, so that it is not exposed to a heating atmosphere. Accurate analysis can be performed without deteriorating the molecular components due to undesired reactions such as oxidation.

However, as a result of repeated studies of the composition analysis of an analytical sample composed of a polymer resin or the like using the gas chromatography pyrolysis apparatus disclosed in the above publication, the present inventors have found that the pyrolysis apparatus also It has been found that when the temperature of the main heating means is increased, the low molecular components may be decomposed. Next, the finding will be described by taking as an example a case where acrylonitrile butadiene rubber (NBR) containing a plasticizer is used as the analysis sample.

The temperature of the main heating means is set to 300 using the pyrolysis apparatus for gas chromatography disclosed in the above publication.
The gas chromatography of the plasticizer contained in the NBR was performed while changing the temperature in the range of -700 ° C. 4 (a) to 4 (e) show that the temperature of the main heating means is 30
The chromatogram at 0 ° C, 400 ° C, 500 ° C, 600 ° C, and 700 ° C is shown.

The NBR is used as the plasticizer as dioctyl adipate (DOA) or dioctyl phthalate (DO).
P), dioctyl sebacate (DOS). The compounds are shown in FIGS.
(D) DOA with a retention time of about 15 minutes in the chromatogram shown
The peak 21 of DOS and the peak 23 of DOS appear in order until the retention time is about 18 minutes.

In the above apparatus, FIGS. 4A and 4B
As is clear from FIG.
At 0 ° C., each of the plasticizers is detected without decomposition. However, as shown in FIG.
In this case, the peaks 21, 22, and 23 of the plasticizers begin to decrease, and a small peak 24 appears at a retention time of about 5 minutes. Peak 24 is considered to be phenol which is a decomposition product of DOP, and it is clear that each of the plasticizers is thermally decomposed.

Further, at 700 ° C., the peaks 21, 22, and 23 of the respective plasticizers disappear, and a large peak 25 appears at a retention time of about 6 minutes. Peak 25 is an unidentified product generated by the decomposition of DOA and DOS.

FIG. 5 shows the relationship between the temperature of the main heating means and the decomposition rate of each plasticizer calculated from the chromatograms shown in FIGS. 4 (a) to 4 (e). As shown in FIG. 5, DOP is changed from when the temperature of the main heating means exceeds 400 ° C.
OA and DOS begin to decompose at slightly below 600 ° C,
It is clear that all the plasticizers decompose.

From the above results, the decomposition of the plasticizer (low molecular weight component) is achieved by providing the main heating means on the outer peripheral portion of the cylinder by the carrier gas by means of the plasticizer vaporized by the sub-heating means. It is considered that the heat is generated by the heating of the main heating means which is operated at the same time as the sub-heating means, when the gas passes through the portion where the gas chromatography column is passed.

From the above considerations, in the pyrolysis apparatus for gas chromatography described in the above publication, the temperature of the main heating means is set to 40
When the temperature is set to 0 ° C. or lower, it is apparent that low-molecular components such as the plasticizer can be separated accurately without being thermally decomposed or deteriorated. However, if the temperature of the main heating means is 400 ° C. or lower, it is difficult to thermally decompose the polymer component.

Therefore, it is conceivable that the temperature of the main heating means is set to 400 ° C. or less while the low molecular components are vaporized, and the temperature is raised to 400 ° C. or more when the high molecular components are thermally decomposed. . However, in order to perform the above with the pyrolysis apparatus for gas chromatography described in the above publication, the temperature of the main heating means is increased for the thermal decomposition of the polymer component, or the temperature of the next sample is measured. Therefore, there is an inconvenience that the operation of cooling becomes complicated. Further, since the heating means is divided into the main heating means and the sub-heating means, there is a possibility of erroneous operation.

[0021]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pyrolysis apparatus for gas chromatography which can solve such inconveniences and can accurately analyze an analytical sample composed of a polymer resin and the like, and which can be easily operated. Aim.

[0022]

The pyrolysis apparatus for gas chromatography according to the present invention is provided with a heating means for pyrolyzing an analysis sample in the pyrolysis apparatus for pyrolysis gas chromatography. An analysis sample supply means for inserting a sample and holding the analysis sample at a position heated by the heating means or at a position not heated is provided, and when the analysis sample is first held at the heating position by the analysis sample supply means, The temperature of the heating means is set to a temperature at which the low-molecular component evaporates, and the temperature of the heating means is changed when the solid sample once held at the position not heated by the analysis sample supply means is again held at the heating position. A heating temperature control means for setting a temperature at which the polymer component is thermally decomposed is provided.

In the pyrolysis apparatus for gas chromatography according to the present invention, the temperature of the heating means is set to a temperature at which a polymer component is pyrolyzed, and then a refrigerant is introduced into the pyrolysis apparatus to cool the heating means. A cooling means is provided. As the refrigerant, compressed air, carbon dioxide, liquid nitrogen, or the like can be used, but it is preferable to use compressed air that can be obtained at low cost. For rapid cooling, carbon dioxide, liquid nitrogen and the like are preferable.

[0024]

In the pyrolysis apparatus for gas chromatography of the present invention, the analysis sample made of a polymer resin or the like inserted into the pyrolysis apparatus by the sample supply means is first held at a heating position by the heating means. At this time, since the heating means is set to a temperature at which the low-molecular components are vaporized by the heating temperature control means, low-molecular components such as a plasticizer contained in the analysis sample are vaporized.

When the low molecular components are vaporized, the sample is moved by the sample supply means to a position not heated by the heating means and held there, and waits until the analysis of the low molecular components by gas chromatography is completed. Let me do.

Next, when the analysis of the low molecular weight component by gas chromatography is completed, the analysis sample is again moved to the heating position by the sample supply means and held. At this time, since the heating means is set to a temperature at which the polymer component is thermally decomposed by the heating temperature control means, the polymer component serving as the base of the resin of the analysis sample is thermally decomposed and vaporized.

According to the pyrolysis apparatus for gas chromatography of the present invention, as described above, the vaporization of the low molecular weight component and the thermal decomposition of the high molecular weight component are performed by changing the heating temperature of a single heating means in two stages. Since it is performed, the vaporized low molecular components are not thermally decomposed or deteriorated. Further, while the low-molecular component is subjected to gas chromatography, the analysis sample is held at a position not heated by the heating unit by the sample supply unit, so that the high-molecular component is exposed to a heated atmosphere. And there is no deterioration due to undesired reactions such as oxidation.

Therefore, the components of the analysis sample can be accurately analyzed for both high-molecular components and low-molecular components. Further, since the single heating means is used, the operation of changing the heating temperature is simplified, and the risk of erroneous operation is reduced.

Further, according to the pyrolysis apparatus for gas chromatography of the present invention provided with the cooling means, when the analysis of one sample is completed, a refrigerant is introduced into the pyrolysis apparatus by the cooling means. By doing so, the heating means, which is heated to a temperature at which the polymer component is thermally decomposed, is easily cooled, and when the next sample is measured,
Temperature adjustment of the heating means is facilitated.

[0030]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a pyrolysis apparatus for gas chromatography according to the present invention. FIG. 1 is an explanatory sectional view of the gas chromatography pyrolysis apparatus of the present embodiment, and FIG. 2 is a graph showing the relationship between the temperature of the heating means and the yield of vaporized low molecular components in the gas chromatography pyrolysis apparatus of the embodiment. FIG. 3 is a graph showing the relationship between the temperature of the heating means and the reproducibility of analysis in the pyrolysis apparatus for gas chromatography of this example.

As shown in FIG. 1, in a pyrolysis apparatus 1 for gas chromatography according to the present embodiment, one end 2a of a cylinder 2 formed of a quartz tube is connected to a gas chromatography column 3 formed of a metal capillary column, and the other end is formed. Is an open end 2b. An electric heater is provided on the outer periphery of the cylinder 2 as heating means 4 for thermally decomposing and vaporizing an analysis sample inserted from the open end 2b.

A large-diameter cylinder 5 is connected to the open end 2 b of the cylinder 2, and the cylinder 5 is provided with a carrier gas inlet 6. The carrier gas inlet 6 is connected to a carrier gas cylinder 7 provided outside the cylinder 5, and the components vaporized by the heating means 4 are supplied to the gas chromatography column 3 by the carrier gas introduced from the carrier gas inlet 6. To be analyzed.

The analysis sample is inserted into the cylinder 5 from the open end 2b by sliding hermetically along the inner diameter thereof, and the analysis sample is heated by the heating means 4 in the cylinder 2.
Sample supply means 1 which is held at a heating position 8 by the heating or at a position 9 not heated by the heating means 4 in the cylinder 5
0 is provided. The analysis sample supply means 10 is provided with a sample holding unit 11 at the tip.

A heating temperature control means 12 and a compressed air cylinder 13 are provided outside the cylinder 2. The heating temperature control means 12 is electrically connected to the heating means 4, and when the analysis sample is first held at the heating position 8 by the analysis sample supply means 10, the temperature of the heating means 4 is reduced by the low molecular weight component. The temperature of the analysis sample supplied by the analysis sample supply means 10 and the heating means 4
The temperature of the heating means 4 is controlled so that the temperature of the polymer component is a temperature at which the polymer component is thermally decomposed.

The compressed air cylinder 13 is provided on the side opposite to the heating temperature control means 12 with respect to the cylinder 2, and is provided with a cooling control device 14. The cooling control device 14 controls the opening and closing of the compressed air cylinder 13. After the heating temperature control means 12 sets the temperature of the heating means 4 to the temperature at which the polymer component is thermally decomposed, the cooling air is released from the compressed air cylinder 13 to the cylinder 2 and the heating Compressed air is introduced around the heating means 4 to cool the heating means 4.

The cylinder 5 is provided with a dead space exhaust valve 13, and the dead space exhaust valve 15 can be opened and closed by an on-off valve 15a. An interface furnace 16 is provided on the outer periphery of the connection between the cylinder 2 and the gas chromatography column 3, and is controlled independently of the heating means 4.

Next, the operation of the pyrolysis apparatus for gas chromatography of this embodiment will be described.

In the gas chromatography apparatus according to the present embodiment, first, an analysis sample made of a polymer resin or the like is fixed to a sample holder 11 provided at the tip of the analysis sample supply means 10. Next, the dead space exhaust valve 15 is opened, a carrier gas is introduced from the carrier gas cylinder 7 into the cylinder 5 through the carrier gas inlet 6, and the air in the cylinder 5 is exhausted. By closing the dead space exhaust valve 13 after the above operation, it is possible to prevent the inside of the cylinder 5 from being replaced with the carrier gas to form a dead space, thereby improving the analysis accuracy.

Next, the analysis sample supply means 10 is slid along the inner diameter of the cylinder 5 and advanced, whereby the analysis sample is inserted into the cylinder 2 from the open end 2b and heated by the heating means 4. It is held at position 8.

At this time, the heating means 4 is set by the heating temperature control means 12 to a temperature at which low molecular components such as a plasticizer contained in the analysis sample are vaporized, so that the low molecular components are vaporized. Next, the vaporized low molecular components are sent into the gas chromatography column 3 by the carrier gas introduced into the cylinder 2 from the carrier gas cylinder 7 through the carrier gas inlet 6.

Next, by heating a column thermostat (not shown) in which the gas chromatography column 3 is mounted to a predetermined temperature, gas chromatography of the low-molecular components is performed. The vaporized low molecular component temporarily stays at the tip of the gas chromatography column 3 until the column thermostat is heated, but the outer peripheral portion of the connection between the cylinder 2 and the gas chromatography column 3 has an interface furnace. The arrangement of 16 prevents the vaporized low molecular components from condensing.

When the low molecular weight component is vaporized, the analysis sample is retreated by the analysis sample supply means 10, moved to a position 9 not heated by the heating means 4 in the cylinder 5, and held therein. Wait until the gas chromatography is completed. By doing so, the analysis sample is not exposed to the heating atmosphere at the heating position 8 until the gas chromatography of the low-molecular component is completed, so that deterioration due to an undesirable reaction such as oxidation can be prevented.

Next, when the gas chromatography of the low molecular weight component is completed, the analysis sample is again moved to the heating position 8 and held by the analysis sample supply means 10 in the same manner as described above. At this time, since the heating unit 4 is set to a temperature at which the polymer component is thermally decomposed by the heating temperature control unit 12, the polymer component serving as the base of the resin of the analysis sample is vaporized. Then, the thermally decomposed polymer component is sent to the gas chromatography column 3 and analyzed by the carrier gas in the same manner as in the case of the low molecular component.

As described above, when the analysis of one sample is completed, the cooling controller 14 controls the compressed air cylinder 13.
Is released, and compressed air is introduced around the cylinder 2 and the heating means 4. The compressed air is exhausted from an exhaust port (not shown), and the heating means 4, which is heated to a temperature at which the polymer component is thermally decomposed by the flowing compressed air, is cooled.
When the heating means 4 is cooled, the compressed air cylinder 13 is closed by the cooling control device 14, and the measurement of the next sample is prepared.

Next, acrylonitrile-butadiene rubber (NBR) containing a plasticizer was analyzed using the pyrolysis apparatus 1 for gas chromatography of this example. The NBR
Represents dioctyl adipate (DO) as the plasticizer
A), dioctyl phthalate (DOP), and dioctyl sebacate (DOS).

In the analysis, the temperature at which the low molecular weight component is vaporized by the heating temperature control means 12 is set to 200 ° C., 300 ° C., 55 ° C.
By setting the temperature at 0 ° C. and 600 ° C. and determining the yield of DOP (see FIG. 5) which is the most thermally decomposable among the plasticizers at each of the temperatures, an appropriate temperature at which the plasticizer can be analyzed without being thermally decomposed. I went for the purpose of examining. The results are shown in FIG.

FIG. 2 clearly shows that the yield of DOP almost coincides with the theoretical value at 300 ° C. (yield of about 100%), and at this temperature, the plasticizer can be accurately analyzed without being thermally decomposed. is there. It is considered that the vaporization of DOP is insufficient at 200 ° C., and that the yield is reduced at 550 ° C. and 600 ° C. due to thermal decomposition.

The above procedure was repeated five times for each temperature, and the reproducibility of the analysis was examined by calculating the coefficient of variation (standard deviation / average value × 100, unit:%). The results are shown in FIG. From FIG. 3, it is apparent that the coefficient of variation is the lowest at about 1% at 300 ° C. and has the highest reproducibility.

Next, using the pyrolysis apparatus 1 for gas chromatography of the present embodiment, the temperature at which the low molecular weight component was vaporized was set to 300 ° C. by the heating temperature control means 12 and the high molecular weight component was pyrolyzed. When the NBR was analyzed at a temperature of 600 ° C., both the low molecular weight component and the high molecular weight component could be accurately analyzed.

[0050]

As is apparent from the above, according to the pyrolysis apparatus for gas chromatography of the present invention, the pyrolysis of the analysis sample composed of the polymer resin or the like is performed by a single heating means. By providing a heating temperature control means for controlling the temperature of the heating means in two stages, it is possible to prevent thermal decomposition or deterioration of the low molecular weight component, and while the low molecular weight component is analyzed, the analysis sample By providing an analysis sample supply means for holding the polymer component at a position not heated by the heating means, it is possible to prevent the polymer component from being exposed to a heated atmosphere and being deteriorated. Therefore, according to the pyrolysis apparatus for gas chromatography of the present invention, the analysis sample can be accurately analyzed for both the low-molecular component and the high-molecular component.

Further, according to the pyrolysis apparatus for gas chromatography of the present invention, since there is only one heating means for performing the thermal decomposition of the analysis sample, the operation of controlling the temperature of the heating means in two stages is required. It is easy and can reduce the risk of malfunction.

According to the pyrolysis apparatus for gas chromatography of the present invention provided with the cooling means, when the analysis of one sample is completed, compressed air is introduced into the pyrolysis apparatus by the cooling means. Therefore, the heating means, which is heated to a temperature at which the polymer component is thermally decomposed, is easily cooled, and when measuring the next sample, the temperature of the heating means is easily set to a temperature at which the low-molecular component is vaporized. be able to.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing one configuration example of a pyrolysis apparatus for gas chromatography according to the present invention;

FIG. 2 is a graph showing the relationship between the temperature of a heating means and the yield of vaporized low-molecular components in the pyrolysis apparatus of this embodiment.

FIG. 3 is a graph showing the relationship between the temperature of a heating means and the reproducibility of analysis in the pyrolysis apparatus for use in the present embodiment;

FIG. 4 is a chromatogram showing an analysis example of an analysis sample made of a polymer resin or the like in a conventional pyrolysis apparatus;

5 is a graph showing the relationship between the temperature of the heating means and the decomposition rate of the plasticizer calculated from the chromatogram shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pyrolysis apparatus for gas chromatography, 4 ... Heating means, 8 ... Heating position, 9 ... Position not heated, 10 ...
Analysis sample supply means, 12 ... heating temperature control means, 13,
14 ... cooling means.

Claims (2)

(57) [Claims] In a pyrolysis apparatus for pyrolysis gas chromatography, a heating means for pyrolyzing an analysis sample is provided, and the analysis sample is inserted into the pyrolysis apparatus and the analysis sample is heated by the heating means. Or provided with an analysis sample supply means to hold at a position not heated, the temperature of the heating means when the analysis sample is first held at the heating position by the analysis sample supply means the temperature at which low-molecular components vaporize, Heating temperature control means for setting the temperature of the heating means to a temperature at which a polymer component is thermally decomposed when the solid sample once held at the position not heated by the analysis sample supply means is again held at the heating position; A pyrolysis apparatus for gas chromatography, which is provided. 2. A cooling means for cooling the heating means by introducing a refrigerant into the pyrolysis apparatus after setting the temperature of the heating means to a temperature at which a polymer component is thermally decomposed. The pyrolysis apparatus for gas chromatography according to claim 1.