JP3322325B2 - Sample concentrator for analysis - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analytical sample concentrator for concentrating trace components contained in a gas or liquid.

[0002]

2. Description of the Related Art When analyzing a trace amount of gas components in the order of ppb contained in a gas or liquid, a method of cooling a sample gas with liquid nitrogen or the like to liquefy and concentrate a target component, and a method of analyzing water. If the target is a component contained in the sample, the sample is stored in a sealed container with a space area, the gas-liquid equilibrium is maintained under certain conditions, and the gas in the container space is sampled as a head space. The law is commonly used.

However, interfering components other than the target substance contained in the sample in a relatively large amount are also concentrated at the same time, and flow into the analysis means as a component having an extremely higher concentration than the component to be analyzed, and the interfering components are removed. Therefore, particularly when it is desired to selectively detect only the regulated components as in environmental measurement, there is a problem that it is difficult to detect the target trace components.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to concentrate components to be measured in an environment with good reproducibility and reliably. To provide a novel sample concentrating device for analysis.

[0005]

According to the present invention, a hollow fiber formed of a polymer material is accommodated in a container so that both ends of the hollow fiber can be connected to an external conduit. An analytical sample concentrator comprising a gas selecting means provided with means for controlling the temperature of the hollow fiber, a pump means for supplying a fluid to be concentrated to the container, and a condenser connected to the hollow fiber. I made it.

[0006]

[Function] When the wall surface of the hollow fiber functions as a molecular sieve having a chemical affinity, or when the hollow fiber is porous, the pores function as a sieve. It cannot be passed because it is adsorbed by the yarn, and only the target component permeates and is adsorbed on the condenser and concentrated. And since the function of such a sieve depends on the temperature of the hollow fiber, by controlling the temperature of the hollow fiber, it is possible to select the target component and to control the transmittance with good reproducibility. Become.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows an embodiment of the present invention. In the drawing, reference numeral 1 denotes gas selecting means, which penetrates a thin thread made of a polymer material, for example, silicon, polyester, fluororesin, etc. from one end to the other end. 1-100μ in diameter
The hollow fiber 2 forming a through hole of m and functioning as a pipe-shaped partition wall is accommodated in the internal space 7 of the cylindrical container 3 so that both ends 2a and 2b can be connected to an external pipeline. Both ends of the cylindrical container 3 are sealed, and a heater 8 for heating the hollow fiber 2 to room temperature or higher, for example, 40 ° C. to 150 ° C. is provided. In the vicinity of the end of the cylindrical container 3, connection ports 4, 5 for connecting to an external pipeline are provided.

Reference numeral 12 denotes a condenser, which is constituted by a column containing an adsorbent that adsorbs a gas to be analyzed in a low temperature state of about room temperature and desorbs the adsorbed gas at about 200 ° C. I have. The condenser 12 has a flash heater 13 around it, one end of which is connected to one end 2 a of the hollow fiber 2 of the gas selecting means 1, and the other end of which is a switching valve 14.
Can be selectively connected to the analysis column 15 and the carrier gas source 16 via the. The other end of the analytical column 15 is connected to a gas chromatograph detector 17. The analysis column 15 and the detector 17 are housed in a thermostat 18 to constitute a gas chromatograph.

Reference numeral 14 denotes a switching valve, which is a carrier gas source 16-.
A first flow path (a flow path indicated by a dotted line of a switching valve in the figure) for communicating the hollow fiber 2-condenser 12-discharge port 23, carrier gas source 16-analysis column 15, and a carrier gas source 16- Hollow fiber 2-condenser 12-analytical column 15
And a second flow path (a flow path shown by a solid line of the switching valve in the figure) connecting the above.

Reference numeral 19 denotes a cylinder serving as a sample measuring means.
One end is connected to the connection port 5 of the cylindrical container 3 of the gas separation means 1 via the plunger pump 20, and the other end is connected to the other connection port 4 of the cylindrical container 3, and the sample inside is hollowed by the plunger pump 20. It is connected so as to circulate the outer periphery of the yarn 2, that is, the space 7 of the cylindrical container 3. Reference numeral 21 in the figure denotes a sample inlet of the sample measuring means 19, and 2
Reference numeral 2 denotes a sample injection mechanism of the gas chromatograph.

In this embodiment, the temperature of the hollow fiber 2 is set by the heater 8 to a temperature at which the target component can be selectively passed, for example, 80 ° C., and the sample is supplied from the sample inlet 21 to the sample measuring means 19. Fill a sample, for example water.

In this state, when the switching valve 14 is switched to the first flow path (the flow path shown by the dotted line in the figure) and the plunger pump 20 is operated, the sample in the sample measuring means 19 is Circulates from the connection port 5 of the cylindrical container 3 into the space 7 and returns to the measuring means 19 from the other connection port 4 again. The carrier gas from the carrier gas source 16 flows from one end 2 b of the hollow fiber 2, and is discharged from the other end 2 a through the outlet 12 through the condenser 12.

The gas component contained in the sample to be analyzed in the course of this circulation is selected by a function determined by the material constituting the hollow fiber 2, for example, in the case of silicon, by permeation into the material, and by fluorine. In the case of the resin, the resin enters the through hole of the hollow fiber 2 by passing through the pore, and is carried to the condenser 12 by the carrier gas.

On the other hand, the interfering component is adsorbed by the affinity of the material constituting the hollow fiber 2 in the process of passing through the partition wall of the hollow fiber 2 or, in the case of the fluororesin, is interposed between the pores and 2 cannot penetrate.

The components that have passed through the hollow fiber 2 are conveyed to the condenser 12 by the carrier gas flowing therein, are adsorbed by the adsorbent of the condenser 12, and are sequentially concentrated.

By the way, when a gas component permeates a polymer membrane such as the hollow fiber 2, a gas permeability coefficient P is generally P = K × D, where K is a gas solubility and D is a diffusion coefficient. It can be represented by a relationship. On the other hand, the solubility of gas is
Since it depends on the temperature of the hollow fiber 2, if the temperature of the heater 8 of the gas selecting means 1 is controlled to change the temperature of the hollow fiber 2,
Since the solubility K of the gas changes, the transmittance of the target gas passing through the hollow fiber 2 can be adjusted. That is, it is possible not only to select the type of gas to be transmitted according to the temperature of the heater 8, but also to control the transmission so that the transmittance is constant.

When the switching valve 14 is switched to the second flow path (the flow path indicated by the solid line of the switching valve 14 in the drawing) at the time when the predetermined time has elapsed, the carrier gas source 16-the hollow fiber 2- Condenser 12-analytical column 15-detecting means 1
7 is formed. At this stage flash heat
When a current is supplied to the capacitor 13, the components adsorbed on the condenser 12 are desorbed from the adsorbent, and are expelled to the analytical column 15 in a very short time by the carrier gas flowing into the adsorbent. The sample that has flowed into the analytical column 15 is
The components are separated by the analysis column 15 and flow into the detector 17 after the elapse of the elution time determined by the column packing material, and the concentration is detected.

Thus, as shown in Table 1, the hollow fiber 2 not only selectively removes organic solvents such as ethanol and acetonitrile and acetic acid, but also prevents the water constituting the sample from permeating. In particular, when the gas component dissolved in water is concentrated, only the gas component can be selectively extracted, and can be analyzed by a gas analyzer that is relatively simple to operate.

[Table 1]

Comparative Example 200 ppb of methanol and 50 pp of chloroform in pure water
b, using a sample in which 100 ppb of benzene was dissolved, the sample was analyzed by the above-described analyzer.
As shown in (1), water and methanol, which are contaminants, were completely eliminated, and peaks of only chloroform (P1) and benzene (P2) could be obtained.

On the other hand, for comparison, when the sample was concentrated by the conventional purge trap method and analyzed by the same analysis means, as shown in FIG. Chloroform (P1) and benzene (P2) were detected with a large peak (P3) of methanol being handled. When a sample having an extremely higher concentration than the component to be analyzed flows in this way, the tail end of the peak becomes longer, and if the peak of the target component is located in this tail end region, an analysis error will be included.

Accordingly, the present invention eliminates organic solvents and the like present in the environment at a relatively high concentration and selectively concentrates the gas to be analyzed. It was found that the overlap between the tail component and the peak of the target component could be prevented, and the trace component could be analyzed at a high concentration.

Naturally, as described above, since the transmittance of the hollow fiber 2 changes depending on the temperature, the target component can be selectively concentrated and taken out of the sample by controlling the temperature of the hollow fiber. it can.

In this embodiment, the independent heater 8 is provided in the gas selecting means. However, the gas selecting means is constituted as a cylindrical container and a module comprising hollow fibers to accommodate the analysis column 15 and the detector 17. It can also be stored in a constant temperature bath 18.

In the above embodiment, the case where only one hollow fiber is accommodated in the cylindrical container has been described. However, the same effect can be obtained even if a plurality of hollow fibers are accommodated in the same container. Is clear.

Further, in the above-described embodiment, the components of the gas are analyzed by gas chromatography. However, the same applies to the case where the components are detected by using a spectrum analyzer or a mass analyzer which does not require a separating means. It is clear that the action of

[0026]

As described above, according to the present invention, a hollow fiber formed of a polymer material is housed in a container so that both ends thereof can be connected to an external conduit, and the temperature of the hollow fiber is controlled. Gas selection means, a pump means for supplying the fluid to be concentrated to the container, and a condenser connected to the hollow fiber. Controlling the temperature eliminates interfering components and not only selectively concentrates trace components to be analyzed, but also uses gas analysis means that is easier to operate than liquid sample analysis. can do.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a gas chromatograph using a sample concentrating device of the present invention.

FIGS. 2A and 2B are a chromatogram showing the results of analysis by the apparatus of the present invention and a chromatogram of a sample obtained by a conventional sample concentration method, respectively.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas selection means 2 Polymer hollow fiber 3 Container 7 Space 12 Condenser 13 Flash heater 14 Switching valve 15 Analysis column 16 Carrier gas source 19 Sample measuring means 20 Pump

──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Kensaku Mizoguchi 1-1-1, Higashi, Tsukuba, Ibaraki Pref., National Institute of Advanced Industrial Science and Technology (72) Inventor Masami Matsui 3-7-1, Azuma, Tsukuba, Ibaraki Co., Ltd. Examiner at Tsukuba Analysis Center, Shimadzu Corporation Shigeo Taka ▼ (56) References JP-A-3-59456 (JP, A) Ogasawara, Masuoka, Mizoguchi, Basics of membrane module for removing organic chlorine-based solvent contaminated with groundwater Study, 58th Annual Meeting of the Society of Chemical Engineers, Abstracts of Research Presentations, March 10, 1993, p. 66 Richard G. Melcher, Paul L .; Moravito,, ANALYTICAL CHEMI STRY, October 15, 1990, VOL. 62 NO. 20, p. 2183-2188 (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 1/10 G01N 1/22 G01N 1/36 G01N 30/08 JICST file (JOIS)

Claims (2)

(57) [Claims] 1. A hollow fiber formed of a polymer material,
A gas selecting means having means for controlling the temperature of the hollow fiber while accommodating both ends thereof in a container so as to be connectable to an external conduit, a pump means for supplying a fluid to be concentrated to the container, and a hollow fiber A sample concentrator for analysis, comprising: a condenser to be connected. 2. The analytical sample concentrator according to claim 1, wherein said hollow fiber is made of a polymer material.