JP2005249691A - Gas chromatograph unit and exhaust gas analytical method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas chromatograph unit and an exhaust gas analytical method of high speed and high sensitivity capable of injecting all the quantity of an exhaust gas sample to obtain a data collectively. <P>SOLUTION: This gas chromatograph unit/exhaust gas analytical method is provided with a water removing part provided with a precolumn A having performance for capturing hydrocarbons having 5 or more of carbon number, a precolumn B having performance for capturing water and a switch valve, and for introducing the gas sample passed through the precolumn A into the precolumn B to remove the water from only the gas sample containing hydrocarbons having 4 or less of carbon number in the gas sample, and an analytical part provided with a hydrocarbon trapping part 21 provided with an enrichment column 22, a cooling means and a heating means, for depositing analyte components in the gas sample passed through the water removing part onto the enrichment column by cooling the enrichment column by the cooing means, and for eliminating the deposited components from the enrichment column by heating the enrichment column by the heating means, so as to enrich the gas sample, and an analytical part provided with a separation column for introducing the gas sample passed through the water removing part and the hydrocarbon trapping part, and a detector 31 for detecting the hydrocarbons. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gas chromatograph apparatus and an exhaust gas analysis method for quickly and highly sensitively analyzing exhaust gas and other sample gas components discharged from automobiles, combustion apparatuses, etc., and more particularly to a gas chromatograph apparatus for analyzing automobile exhaust gas And an exhaust gas analysis method.

  For example, automobile exhaust gas contains a wide variety of compounds having different carbon numbers, and it has been extremely difficult to measure all components with a single gas chromatograph. Therefore, in the conventional exhaust gas analysis method, the gas components are divided in advance according to the molecular weight (for example, separated into hydrocarbons having 5 or less carbon atoms and hydrocarbons having 6 or more carbon atoms), and then analysis must be performed individually. (For example, refer to Patent Document 1). Such an analysis method requires separation columns and detectors corresponding to the number of divisions, and requires a plurality of gas chromatograph apparatuses or a complicated system. Moreover, complicated data processing for unifying data obtained from a plurality of detectors is also required, and the operation is very complicated.

  On the other hand, it has been reported that a large amount of water in the exhaust gas from automobiles causes noise on the chromatogram and fluctuates the retention time of the separation column (see, for example, Non-Patent Document 1). Even in the analysis of exhaust gas from which moisture has been removed, the division of gas components by molecular weight is essential, and two or more columns and detectors are required.

It is very time-consuming to measure gas components in detail after separating them in detail with a column. Not only is there a limit to the number of samples that can be measured, but there is also concern about sample deterioration. With the recent tightening of exhaust regulations and more efficient vehicle development, there is a demand for higher sensitivity and speed of exhaust analysis, and the establishment of a method for analyzing exhaust gases simultaneously in a single column. The present inventors have proposed a method of introducing exhaust gas directly into a gas chromatograph apparatus and analyzing it with a single column (see, for example, Non-Patent Document 2), but the analysis time is about 50 minutes per sample. Therefore, since the lower limit of quantification was about 500 ppb, it was necessary to improve the speed and sensitivity in practical use.
JP-A-6-222048 Akiyama, Sakamoto; "Development of HC analysis method in automobile exhaust gas using large-capacity measuring tube" analytical chemistry vol. 43 (1994) p785-789 Yamamoto, Ito, Oshima; Abstracts of the 57th Analytical Chemistry Conference of the Analytical Society of Japan, “Development of Analytical Methods for Hydrocarbons in Automobile Exhaust Gas (Part 1) Direct Introduction-Total Composition Analysis by GC Method” (1996) P) 61-62

  An object of the present invention is to provide a gas chromatograph apparatus and an exhaust gas analysis method which can inject a whole amount of an exhaust gas sample to obtain collective data and which are quick and highly sensitive.

The object of the present invention has been achieved by the following gas chromatograph apparatus and exhaust gas analysis method.
<1> a step of separating hydrocarbons having 5 or more carbon atoms and hydrocarbons having 4 or less carbon atoms in exhaust gas;
Removing water from exhaust gas containing hydrocarbons having 4 or less carbon atoms;
A step of concentrating and vaporizing an exhaust gas containing hydrocarbons having 4 or less carbon atoms from which water has been removed and an exhaust gas containing hydrocarbons having 5 or more carbon atoms;
Passing the concentrated and vaporized hydrocarbons through a separation column;
Detecting hydrocarbons that have passed through the separation column with a detector;
An exhaust gas analysis method comprising:

<2> Precolumn (A) having the capability of capturing hydrocarbons having 5 or more carbon atoms, precolumn (B) having the capability of capturing water, and a switching valve for switching the gas flow path, and passing through the precolumn (A) A sample removing gas is introduced into the precolumn (B), and water is removed only from the sample gas containing hydrocarbons having 4 or less carbon atoms in the sample gas;
A concentration column, a cooling means, and a heating means are provided. By cooling the concentration column with the cooling means, the component to be analyzed in the sample gas that has passed through the water removal unit is attached to the concentration column, and the concentration column is heated with the heating means. A hydrocarbon trap for desorbing the components adhering to the concentration column and concentrating the sample gas;
An analysis unit including a separation column into which a sample gas that has passed through the water removal unit and the hydrocarbon trap unit is introduced and a detector that detects hydrocarbons;
A gas chromatograph apparatus comprising:
<3> The gas chromatograph device according to <2>, wherein the precolumn (A) is a packed column or a capillary column containing a filler.
<4> The gas chromatograph device according to <2> or <3>, wherein the precolumn (B) is a packed column containing a packing material.
<5> The gas chromatograph device according to any one of <2> to <4>, wherein the analysis unit includes one separation column and one detector.
<6> The gas chromatograph device according to any one of <2> to <5>, wherein the water removing unit further includes a measuring tube.
<7> The switching valve of the water removal unit is provided in each of the pre-column (A), the pre-column (B), and the measuring tube, and any one of the items <2> to <6> The gas chromatograph apparatus described.
<8> The water removal unit is characterized in that the switching valve of the precolumn (A) is a four-way valve, the switching valve of the precolumn (B) is a six-way valve, and the switching valve of the measuring pipe is a ten-way valve. The gas chromatograph device according to <7>.

<9> The <2> to <8>, wherein the hydrocarbon trap part further includes a second cooling unit and a second heating unit in addition to the cooling unit and the heating unit. A gas chromatograph apparatus according to claim 1.
<10> The gas chromatograph device according to any one of <2> to <9>, wherein the separation column is a capillary column having an inner diameter of 0.2 mm or less.
<11> The gas chromatograph device according to any one of <2> to <9>, wherein the separation column is a capillary column having an inner diameter of 0.18 mm or less.
<12> The control unit according to any one of <2> to <11>, further comprising a control unit that controls switching timing of the switching valve and controls operation of the cooling unit and the heating unit. Gas chromatograph device.
<13> The gas chromatograph device according to any one of <2> to <12>, wherein the detector of the analysis unit is at least one of a flame ion detector and a mass detector.

According to the present invention, a gas chromatograph apparatus and an exhaust gas analysis method that can inject a whole amount of an exhaust gas sample and obtain batch data and that are quick and highly sensitive are provided.

The inventors examined the detection limit and factors that hinder the analysis accuracy when the exhaust gas sample was injected and analyzed. As a result of detailed analysis, as shown in FIG. 1, it was found that moisture in the exhaust gas has a large influence on low carbon number components, particularly hydrocarbons having 4 or less carbon atoms. It became clear that the retention time of the low carbon number component was delayed and the peaks overlapped due to a large amount of water.
Therefore, in consideration of rapid processing, the inventors have invented an exhaust gas analysis method that removes moisture only from hydrocarbons having 4 or less carbon atoms. The exhaust gas analysis method of the present invention includes a step of separating hydrocarbons having 5 or more carbon atoms and hydrocarbons having 4 or less carbon atoms in the exhaust gas, and a step of removing water from the exhaust gas containing hydrocarbons having 4 or less carbon atoms. , A step of concentrating and vaporizing exhaust gas containing hydrocarbons having 4 or less carbon atoms from which water has been removed and exhaust gas containing hydrocarbons having 5 or more carbon atoms and passing the concentrated and vaporized hydrocarbons through a separation column And a step of detecting hydrocarbons that have passed through the separation column with a detector.

As a method for separating hydrocarbons having 5 or more carbon atoms and hydrocarbons having 4 or less carbon atoms in the exhaust gas, a method using a filler or a method using a capillary column is preferable. The filler has a stationary phase liquid (liquid phase) and a carrier that supports and fixes the liquid phase, and the capillary column is a column in which the inner wall of a hollow long capillary is coated with the liquid phase. The liquid phase is preferably dimethylpolysiloxane. As the filler carrier, a diatomaceous earth carrier, a carbon carrier, a fluorine resin carrier, or the like can be used as appropriate.
In addition, as a method for removing water from the exhaust gas, a method such as using a filler such as silica gel to trap water in the filler, or collecting the exhaust gas in a tetra bag and condensing moisture on the bag surface, the water vapor concentration in the gas There are a method of lowering water, a method of removing moisture using a membrane, a method of drying exhaust gas through a perm pure dryer, and a method of concentrating at room temperature using a nonpolar porous polymer. The method is preferably a method in which a filler such as silica gel is used to trap water in the filler, or a method of removing water using a membrane, and more preferably a method in which water is trapped in the filler.
In order to concentrate and vaporize the exhaust gas, cooling / heating means are usually used, but in addition, room temperature concentration / vacuum evaporation means and the like can also be used. A method of concentrating and vaporizing by cooling and heating is preferable. Any method can be adopted as the cooling / heating method, but cooling by liquid nitrogen and heating by energization are preferred.

Furthermore, the present inventors also invented a gas chromatograph apparatus for realizing this exhaust gas analysis method. The gas chromatograph apparatus of the present invention includes a precolumn (A) having a performance of capturing hydrocarbons having 5 or more carbon atoms, a performance of capturing water (B), and a switching valve for switching a gas flow path. A sample gas that has passed through A) is introduced into the pre-column (B), and water is removed only from the sample gas containing hydrocarbons having 4 or less carbon atoms in the sample gas, a concentration column, cooling means, and heating means. The component to be analyzed in the sample gas that has passed through the water removal unit is attached to the concentration column by cooling the concentration column with a cooling means, and the attached component is removed from the concentration column by heating the concentration column with a heating means. A hydrocarbon trap part that desorbs and concentrates the sample gas, a separation column into which the sample gas that has passed through the water removal part and the hydrocarbon trap part is introduced, and a hydrocarbon Further characterized in that it comprises an analysis unit comprising a detector for detecting a switching valve provided to one system of the analyzer was performed designed to be switched a gas flow path. Thereby, after capturing hydrocarbons having 5 or more carbon atoms in the pre-column (A), hydrocarbons having 4 or less carbon atoms including water are sent to the pre-column (B), and then the valve is switched to change the gas flow path to the pre-column. After changing to (B) only, the hydrocarbons having 4 or less carbon atoms, from which moisture was removed by the precolumn (B), were sent to the hydrocarbon trap part, the valve was returned again, and the number of carbons captured by the precolumn (A) Five or more hydrocarbons can be sent to the hydrocarbon trap part, and it becomes possible to simultaneously detect hydrocarbons in the sample gas.

  In addition, in order to make the broad peak of the chromatogram a sharp peak and avoid overlapping of the peaks, the hydrocarbon trap in the sample gas that has passed through the precolumns (A) and (B) is cooled and trapped to concentrate the hydrocarbon. Set up a section. The sample gas that has passed through the pre-columns (A) and (B) is mixed in the hydrocarbon trap section and can be detected by the detector all at once.

The gas chromatograph apparatus of the present invention includes (1) a water removal unit, (2) a hydrocarbon trap unit, and (3) an analysis unit. As an example, a gas chromatograph apparatus for exhaust gas analysis will be described with reference to FIGS.
As shown in FIGS. 2 and 3, in the water removal unit 11, only the moisture in the sample gas containing C2 to C4 hydrocarbons is removed by the precolumn (A) 12 and the precolumn (B) 13. The hydrocarbon trap unit 21 is disposed between the water removal unit 11 and the analysis unit 31, and is intended to reduce the peak width of each analysis target component so as to achieve high sensitivity and high performance. In the hydrocarbon trap part 21, the sample gas is concentrated by cooling and heating, and the concentration of the hydrocarbon component to be analyzed in the sample gas is increased. The analysis unit 31 detects hydrocarbons contained in each concentrated sample gas using a separation column and a detector. In addition to these, a control unit 41 is provided, and in order to realize the operation of each unit described above, the switching of the switching valve and the operation of the cooling means and the heating means are controlled.

  Next, the structure of the gas chromatograph apparatus of the present invention will be described in detail with reference to FIG.

1. Water removal unit The water removal unit includes at least a precolumn (A) 12 having the ability to capture hydrocarbons having 5 or more carbon atoms, a precolumn (B) 13 having the ability to capture water, and the precolumn (A) 12 and the precolumn. (B) a switching valve for switching the 13 gas flow paths. In addition, a measuring tube 14, a pressure controller (PC1 to PC3), a mass flow controller (MC1 to MC3), and the like may be provided.
The precolumn (A) may be a packed column containing a filler or a capillary column, but is more preferably a packed column containing a filler. The “filler having the ability to capture hydrocarbons having 5 or more carbon atoms” is not particularly limited as long as it has such a performance, and examples thereof include alumina, dimethyl silicone gum, porous polymer beads and the like. It is done. Preferred are dimethyl silicone gum and porous polymer beads, and more preferred are porous polymer beads. Specific examples of the filler having the capability of capturing hydrocarbons having 5 or more carbon atoms include GL Sciences active alumina, GL Sciences OV-1, and GL Sciences Tenax GR. The liquid phase used in the capillary column is preferably dimethylpolysiloxane. Specifically, HP-1 manufactured by Agilent, DB-1 manufactured by J & W can be used as the capillary column.
The precolumn (B) may be a packed column containing a filler or water removal using a membrane, but is preferably a packed column containing a filler. The “filler having the ability to trap water” is not particularly limited as long as it has such a performance, and examples thereof include activated carbon, molecular sieve, silica gel and the like. Molecular sieves and silica gel are preferable, and silica gel is more preferable. Specific examples of the filler having the ability to trap water include GL Sciences Active Carbon, GL Sciences Molecular Sieve 5A, and GL Sciences Unipack S.

In the water removal unit, the sample gas (exhaust gas from an automobile, etc.) sucked from the sample introduction port 15 by the pump P is measured and passed through a switching valve V1 provided between the sample introduction port 15 and the pump P. The sample gas containing the C2-C4 hydrocarbon and the sample gas containing the C5-C12 hydrocarbon are separated by the precolumn (A) 12, and only the sample gas containing the C2-C4 hydrocarbon is pre-column (B). The pre-column (A) and the pre-column (B) sent to 13 are provided with switching valves V2 and V3, respectively. The sample gas containing C5 to C12 hydrocarbons captured in the precolumn (A) and the sample gas containing C2 to C4 hydrocarbons after moisture removal processed in the precolumn (B) are switching valves V1, V2. , And V3 are returned to the switching bubble V1 at different switching timings. By shifting the timing of the switching valve, analysis in a single column is possible without requiring a complicated operation. The switching valve V1 is a ten-way valve, and includes a sample introduction port, a pump, both ends of a measuring tube, a carrier gas, a switching valve V2 connected to the precolumn A, a switching valve V3 connected to the precolumn B, a hydrocarbon trap section, and a purge gas inlet / outlet. Connected. The switching valve V2 is a four-way valve, and is connected to both ends of the pre-column A, the switching valve V1, and the switching valve V3. The switching valve V3 is a six-way valve and is connected to the switching valve V1, the switching valve V2, both ends of the precolumn B, and the purge gas inlet / outlet. Furthermore, a mass flow controller MC1 and a pressure controller PC1 may be connected to these switching valves. In this case, the switching valve V1 is preferably a ten-way valve, the switching valve V2 is a four-way valve, the switching valve V3 is a six-way valve, and the mass flow controller MC1 and the pressure controller PC1 are preferably connected to the ports of the switching valve V1. Further, as control for the purge gas, it is preferable to connect the mass flow controller MC2 and the pressure controller PC2 to the other port of the switching valve V1, and further connect the mass flow controller MC3 and the pressure controller PC3 to the port of the switching valve V3.

Further, the sample gas trapped in the precolumn (A) is desorbed by heating, but the heating is performed by supplying a current from the power source H2 or by heating with hot air. Preferably, heating is performed by passing an electric current. The heating temperature is preferably 120 ° C. or higher and 350 ° C. or lower, more preferably 180 ° C. or higher and 200 ° C. or lower.
The water removal unit can further include a chalk column, a dummy column, and the like.
The measuring tube is kept at a temperature of 100 ° C. to 250 ° C., preferably 180 ° C. to 220 ° C., in order to prevent adsorption of sample gas and condensation of moisture. The precolumn (B) is kept at a temperature of 120 ° C. to 200 ° C., preferably 120 ° C. to 160 ° C., in order to separate C2 to C4 hydrocarbons and water. The insulation of the measuring tube and the precolumn (B) is preferably heating by energization from the power source H1 and the power source H3 or heating by hot air, but more preferably heating by flowing current from the power source H1 and the power source H3.

2. Hydrocarbon trap part In the hydrocarbon trap part 21, hydrocarbon gas is trapped by the concentration column 22 by cooling, and then the trapped hydrocarbon is vaporized and desorbed by rapid heating. The hydrocarbons in the exhaust gas are concentrated by cooling attachment-heating, and the chromatographic peak width is narrow and sharp. The cooling means is liquid nitrogen, liquid helium, liquid oxygen, or the like, preferably cooling with liquid nitrogen. The heating means is preferably heating by electric current, heating by hot air, etc., more preferably heating by electric current.
The cooling temperature of the hydrocarbon trap part 21 is preferably −190 ° C. to −100 ° C., more preferably −160 ° C. to −100 ° C., and still more preferably −150 ° C. to −140 ° C. When the cooling temperature is lower than −190 ° C., nitrogen and oxygen in the sample gas are condensed and clogged. When the cooling temperature is higher than −100 ° C., the adhesion rate of hydrocarbons having 2 carbon atoms is reduced and it is difficult to condense.
The faster the rate of temperature rise during rapid heating, the higher the separation performance in the separation column, which is preferable, but it is about 0.5 ° C./second to 200 ° C./second.
A preferable heating temperature is 120 ° C to 350 ° C, more preferably 150 ° C to 250 ° C, and further preferably 200 ° C to 250 ° C. If the heating temperature is less than 120 ° C, vaporization of the high boiling point component in the sample gas becomes insufficient, and if it exceeds 350 ° C, the filler and some hydrocarbons may be decomposed.

As shown in FIG. 3, the hydrocarbon trap part 21 has the concentration column 22 filled with the normal filler. Examples of the filler include porous polymer beads and carbon molecular sieve, and specific examples include Tenax GR manufactured by GL Sciences Corporation and Carboxen 1000 manufactured by Spellco Corporation. The concentration column 22 is connected to the port of the switching valve V1 of the water removal unit.
Examples of the heat desorption system include Gerstel, CIS4, and GL Sciences MF258. In the case of CIS4, it is possible to cool the column 22 to about −150 ° C. by flowing liquid nitrogen. Moreover, rapid heating to about 350 ° C. is possible at an arbitrary temperature increase rate of 0.5 to 12 ° C./second.
Furthermore, in order to increase sensitivity and accuracy, it is also a preferable aspect to provide two or more cooling-heat desorption systems. It is particularly important to increase sensitivity and accuracy in a gas chromatography device that obtains data collectively in a single path. When the second cryofocus 23 (second-stage cooling-heat desorption system) is provided, the second cryofocus 23 is not provided with a column filled with a filler, but from the outside of the column 24 that is a part of the tip of the separation column 32. It may be cooled only with liquid nitrogen or the like. Due to the cooling action, hydrocarbons in the exhaust gas adhere to the inner wall of the column, and desorption from the inner wall is rapidly performed during heating, so that the peak width can be narrowed. When the second-stage cooling-heat desorption system is provided, the preferred cooling temperature, heating rate, and heating temperature are the same as those of the first-stage cooling-heat desorption system.

3. Analysis Unit The analysis unit is provided with a separation column 32 and a detector 33. The separation column 32 may be either a packed column or a capillary column, but it is preferable to use a capillary column in order to achieve rapidity, high accuracy, and high sensitivity. In the case of a capillary column, the inner diameter of the column is preferably 0.2 mm or less, more preferably 0.18 mm or less, and even more preferably 0.10 mm or less in order to perform separation simultaneously with one column. . As a detector, a flame ion detector (FID) is generally used, but in addition, a thermal conductivity type detector (TCD), an electron capture type detector (ECD), a flame thermal ion detector (FTD), a flame A photometric detector (FPD), a photoionization detector (PID), a mass detector (MSD), or the like may be used. A combination of these detectors is also possible. It is preferable to control the temperature because the temperature greatly affects the retention time and resolution of each component in the separation column. The temperature of the separation column is preferably maintained at −60 ° C. to 350 ° C., more preferably −55 ° C. to 250 ° C. It is preferable that the temperature of the separation column is also controlled by the controller described below. In addition, the analyzer can be provided with a splitter or the like for simultaneous detection by a plurality of detectors (for example, FID and MSD).

4). As shown in FIG. 4, the control unit 41 includes the pump P, the switching valves V1 to V3, the liquid nitrogen valves NV2 to NV4, the power supplies H1 to H5, the pressure controllers PC1 to PC3, the mass flow controllers MC1 to MC3, and the like. And are driven at each timing described later. The control unit 41 may be configured by a microcomputer, or may be configured by a sequencer and a relay.

  Next, the operation procedure of the exhaust gas analysis by the gas chromatograph apparatus of the present invention will be described.

(1) Weighing First, the flow path of the switching valve V1 is set to the position shown in black in FIG. The sample gas (such as automobile exhaust gas) sucked from the inlet 14 is discharged by the switching valve V1-metering pipe (14) -pump P.

When the sample gas is sufficiently introduced into the measuring tube 14 that is kept warm by the power source H1, the control unit 41 rotates the switching valve V1 by 36 ° to bring the flow path to the white position, and activates the mass flow controller MC1 to activate the carrier. Switch gas and feed to valve V1. Thereby, the flow path of mass flow controller MC1-switching valve V1-metering pipe 14-switching valve V1-switching valve V2 is comprised, and predetermined amount (for example, 50 ml) sample gas stored in metering pipe 14 is mass flow. It is pushed by the carrier gas from the controller MC1 and sent to the switching valve V2. The sample gas sent to the switching valve V2 passes through the precolumn (A). In the precolumn (A), a sample gas containing C5 to C12 hydrocarbons is captured. When all the sample gases containing the remaining C2-C4 hydrocarbons have passed through the pre-column (A), the switching valve V2 is rotated by 90 ° so that the flow path of the switching valve V2 is painted black. A sample gas containing hydrocarbon is retained in the precolumn (A). During this time, the sample gas containing C2-C4 hydrocarbons passes through the switching valve V3 and is sent to the precolumn (B) that is kept warm by the power source H3. In the precolumn (B), C2 to C4 hydrocarbons and water are separated. When all the C2 to C4 hydrocarbons pass from the pre-column (B), the switching valve V3 is rotated by 60 ° so that the flow path of the switching valve V3 is painted black. The mass flow controller MC3 is activated to flow barge gas, and water remaining in the precolumn (B) is removed. During this time, the C2 to C4 hydrocarbons that have passed through the precolumn are sent again to the switching valve V3 and returned to the switching valve V1. Then, it is sent to the hydrocarbon trap part.
On the other hand, after all the C2 to C4 hydrocarbons are sent to the hydrocarbon trap portion, the switching valve V2 is returned to the position where it is painted white by 90 °. Thereafter, heating is performed to desorb the sample gas containing C5 to C12 hydrocarbons captured by the precolumn (A). Heating is performed by supplying a current from the power source H2 or by heating with hot air. The desorbed sample gas returns to the switching valve V1 through the flow path of the switching valve V2-switching valve V3-switching valve V1, and is sent to the hydrocarbon trap section. Thereafter, the rotation of the switching valve V1 is returned by 36 °, and the flow path of the switching valve V1 is set to the position painted black. The mass flow controller MC2 is activated to flow purge gas, and the precolumn (A) is aged.

(2) Concentration The sample gas that has passed through the precolumn (A) and the precolumn (B) is sent to the hydrocarbon trap section through the switching valve V1. The sample gas passes through the column 22 cooled by liquid nitrogen, and during that time, the hydrocarbon component in the sample gas adheres to the surface of the packing material at a low temperature.

  Next, a current is supplied from the power source H4 to the column 22 to heat the column 22 and desorb the attached sample gas. When the cooling attachment-heating system has one stage, the desorbed sample gas is sent to the analysis unit. In the case of providing two stages of the cooling adhesion-heating system, the second cryofocus 23 is provided following the column 22. By repeating cooling and heating, the band width of the sample gas becomes narrow. Here, the second cryofocus 23 may not be provided with a column packed with a packing material, but may only be cooled with liquid nitrogen or the like from the outside of the column 24 which is one end portion of the separation column. When the second cryofocus 23 or the column 24 is cooled to a low temperature with liquid nitrogen and the sample gas is passed therethrough, the analysis target component in the sample gas is attached to the inner wall of the second cryofocus 23 or the column 24. Thereafter, by heating the second cryofocus 23 or the column 24, the attached components can be desorbed at a high speed. The sample gas desorbed by the second cryofocus 23 or the column 24 is sent to the analysis unit.

(3) Analysis The sample gas concentrated through the hydrocarbon trap section passes through the separation column 32, where each component is separated. In the detector 33, the carbon number components of the separated components C2 to C12 are simultaneously measured with high sensitivity and analyzed. Moreover, since it can analyze all at once with one column, complicated data processing is unnecessary.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

A schematic diagram of a gas chromatograph apparatus according to an embodiment of the present invention is shown in FIG.
In the water removal unit, unipack S manufactured by GL Sciences was used as the filler for the precolumn (A), and Tenax GR manufactured by GL Sciences was used as the filler for the precolumn (B). As a carrier gas, He gas was flowed at a rate of 100 ml / min.
In the hydrocarbon trap part, CIS4 manufactured by Gerstel Co. using Tenax as a filler was used as the first cooling-desorption system. Furthermore, a second cryo 24 was provided as a second cooling-desorption system. The desorption by heating at a cooling temperature of −190 ° C. was performed by increasing the temperature of the thermostat bath of the gas chromatograph bluff after stopping the cooling of liquid nitrogen.
In the analysis part, a narrow bore column having a length of 40 m and an inner diameter of 0.18 mm was used as the separation column.
A total amount of 10 ml of exhaust gas was injected into such a gas chromatograph apparatus.

On the other hand, FIG. 6 shows a schematic configuration diagram of a conventional gas chromatograph apparatus as a comparative example. The sample gas was introduced using a thermal gas sampler manufactured by Shimadzu Corporation. GC5890 manufactured by Hewlett-Packard was used as the gas chromatograph. As the separation column, a capillary column having a length of 60 m and an inner diameter of 0.25 mm was used.
The gas chromatograph of this comparative example was injected with 5 ml of exhaust gas at a split ratio of 1/35.

The chromatograph in the apparatus of the said invention and the apparatus in the apparatus of a comparative example are shown in FIG.
In the gas chromatograph apparatus of the present invention, the analysis time is 10 minutes, which can be shortened to about 1/5 time as compared with the comparative example which is a conventional gas chromatograph apparatus. Moreover, the lower limit of quantification was 5 ppb, which was 1/100 of the comparative example.

Gas chromatogram showing the effect of moisture in the exhaust gas. The schematic block diagram of the rapid and highly sensitive gas chromatograph apparatus for exhaust gas analysis of this invention. The schematic block diagram of the gas chromatograph apparatus of this invention. The control system figure of the gas chromatograph apparatus of this invention. The schematic block diagram of the gas chromatograph apparatus of an Example. The schematic block diagram of the gas chromatograph apparatus of a comparative example. The chromatogram of the exhaust gas of the motor vehicle produced by the gas chromatograph apparatus of an Example and a comparative example.

Explanation of symbols

11 Water removal part 12 Column (A)
13 Column (B)
14 Metering tube 15 Sample inlet 21 Hydrocarbon trap 22 Concentration column 23 Second cryofocus 24 Column (tip of separation column)
31 Analyzing unit 32 Separation column 33 Detectors H1, H2, H3, H4, H5 Heater power supply MC1, MC2, MC3 Mass flow controller NV2, NV3, NV4 Liquid nitrogen valve P Pump PC1, PC2, PC3 Pressure controller V1, V2, V3 1 to 10 of switching valve V1, 1 to 4 of V2, 1 to 6 of V3 Port number of each switching valve

Claims (13)

Separating the hydrocarbon having 5 or more carbon atoms and the hydrocarbon having 4 or less carbon atoms in the exhaust gas;
Removing water from exhaust gas containing hydrocarbons having 4 or less carbon atoms;
A step of concentrating and vaporizing an exhaust gas containing hydrocarbons having 4 or less carbon atoms from which water has been removed and an exhaust gas containing hydrocarbons having 5 or more carbon atoms;
Passing the concentrated and vaporized hydrocarbons through a separation column;
Detecting hydrocarbons that have passed through the separation column with a detector;
An exhaust gas analysis method comprising: A pre-column (A) having the capability of capturing hydrocarbons having 5 or more carbon atoms, a pre-column (B) having the capability of capturing water, and a switching gas for switching the gas flow path, and a sample gas that has passed through the pre-column (A) Is introduced into the pre-column (B), and the water removing unit removes water only from the sample gas containing hydrocarbons having 4 or less carbon atoms in the sample gas;
A concentration column, a cooling means, and a heating means are provided. By cooling the concentration column with the cooling means, the component to be analyzed in the sample gas that has passed through the water removal unit is attached to the concentration column, and the concentration column is heated with the heating means. A hydrocarbon trap for desorbing the components adhering to the concentration column and concentrating the sample gas;
An analysis unit including a separation column into which a sample gas that has passed through the water removal unit and the hydrocarbon trap unit is introduced and a detector that detects hydrocarbons;
A gas chromatograph apparatus comprising:   The gas chromatograph according to claim 2, wherein the precolumn (A) is a packed column or a capillary column containing a packing material.   The gas chromatograph apparatus according to claim 2 or 3, wherein the pre-column (B) is a packed column containing a packing material.   5. The gas chromatograph device according to claim 2, wherein the analysis unit includes a single separation column and a single detector. 6.   The gas chromatograph according to any one of claims 2 to 5, wherein the water removing unit further includes a measuring tube.   The switching valve of the said water removal part is provided in the said precolumn (A), the said precolumn (B), and the said measuring tube, respectively, The any one of Claims 2-6 characterized by the above-mentioned. Gas chromatograph device.   The switching valve of the pre-column (A) is a four-way valve, the switching valve of the pre-column (B) is a six-way valve, and the switching valve of the measuring pipe is a ten-way valve in the water removal unit. 8. The gas chromatograph apparatus according to 7.   The hydrocarbon trap section further includes a second cooling unit and a second heating unit in addition to the cooling unit and the heating unit, according to any one of claims 2 to 8. The gas chromatograph apparatus described.   The gas chromatograph apparatus according to any one of claims 2 to 9, wherein the separation column is a capillary column having an inner diameter of 0.2 mm or less.   The gas chromatograph apparatus according to any one of claims 2 to 9, wherein the separation column is a capillary column having an inner diameter of 0.18 mm or less.   The gas chromatograph according to any one of claims 2 to 11, further comprising a control unit that controls switching timing of the switching valve and controls operation of the cooling unit and the heating unit. apparatus.   The gas chromatograph device according to any one of claims 2 to 12, wherein the detector of the analysis unit is at least one of a flame ion detector and a mass detector.

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