JP2008249572A - Sample pretreatment device and gas chromatography analysis method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample pretreatment device and a high-sensitivity gas chromatography analysis method, enabling injection of a large volume of trace constituent sample in a solution. <P>SOLUTION: The device comprises an adsorption tube insertion section that an adsorption tube filled with adsorbent is inserted, a gas introduction section that gas is introduced to the adsorption tube, and syringe spigot section that a syringe is inserted to inject a sample solution, and in the device, the sample solution is injected to the adsorption tube filled with the adsorbent, only the solvent in the adsorption tube is removed by flowing the gas in the adsorption tube, the adsorption tube filled with this adsorbent having the trace constituent sample concentrated is mounted in a heating and desorbing device for a gas chromatography analyzer, the adsorption tube is heated and the adsorbent component that is adsorbed by the adsorbent for a fixed time is desorbed to a cooled liner section, thereafter, the liner section is rapidly heated at a high temperature and this adsorbent component is injected and filled in a column, and then, the trace constituent sample in the solution is analyzed by a mass spectrometer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sample pretreatment apparatus and a highly sensitive gas chromatography analysis method that enable a large amount of a trace component sample in a solution to be injected.

  In a microanalysis using a gas chromatograph / mass spectrometer, a splitless method is known as a sample injection method when analyzing a liquid sample in which a trace amount of unknown components is dissolved in a solvent. The splitless method is a method in which the entire sample is injected, the sample is vaporized at the injection port, transferred to a column, and separated for mass spectrometry. In this method, a liner is installed at the sample injection port, and the sample is vaporized there, but the sample can be injected only to the extent that the vaporization volume does not exceed the liner volume, and the amount is usually 1 to 2 μl. Therefore, in the case of a liquid sample in which only a very small amount of unknown component is dissolved, the amount of unknown component contained in 1 to 2 μl cannot be detected as a peak even if 1 to 2 μl is injected. There was a problem that unknown components could not be identified.

  In order to solve the above problem, there is a pulsed splitless method in which the injection volume can be increased by increasing the pressure at the injection port and reducing the vaporization volume after the liquid sample is injected. However, even in this method, the injection volume is about 5 μl.

  Further, in order to solve the above problem, there is a program temperature vaporization injection method (PTV method) as a sample injection port of a gas chromatograph. The PTV method can change the temperature of the injection port by adding a temperature program function to the injection port. There is a method of injecting a sample in a solvent vent mode using this inlet. That is, after injecting the liquid sample at a temperature slightly lower than the solvent vaporization temperature with the vent line in the liner portion closed, the vent line is opened and the temperature is raised to a temperature at which the solvent vaporizes, and the carrier gas is discharged. When flowed, only the solvent can be removed from the vent line. According to this method, even if the injection amount of the liquid sample in which the trace component is dissolved is increased, the solvent is removed and the target component remains held on the liner. Then, raise the vaporization temperature at once and introduce the components into the column for analysis. Various methods of mass injection using the PTV method have been studied, such as using an inlet liner filled with a packing material, or evaporating the solvent from the vent line and concentrating the target component at a single point on the column for mass injection. A method that enables this is also being developed.

  The PTV method has made it possible to inject a larger amount of liquid sample than the splitless method or the pulsed splitless method. However, since the amount of the sample is long because of the large amount, the peak bandwidth tends to be widened. . Furthermore, since the capacity of the inlet liner of the gas chromatograph is limited, the amount that can be injected is generally 50 μl to 250 μl, and the maximum is about 1 ml. In addition, there were concerns about the effort to optimize the injection conditions (column flow rate, purge flow rate, oven temperature program) and the need to frequently replace the liner because the liner was easily contaminated by introducing a large amount of sample.

  In addition to the PTV method, a sample mass injection method using an on-column method is also performed. In the on-column method, a precolumn is introduced before a separation column, and after injecting a sample, the precolumn is set to a temperature at which only the solvent is vaporized, and the solvent is removed. At this time, the target component is held on the precolumn and the inlet liner. Thereafter, the temperature is raised and components are transferred to the separation column to separate the components. As in the PTV method, the injection amount is generally about 50 μl to 250 μl, and there is a concern about contamination of the precolumn.

The known literature is described below.
JP 2000-2695 A

  The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a sample pretreatment apparatus and a highly sensitive gas chromatography analysis method capable of injecting a large amount of a trace component sample in a solution. is there.

The invention according to claim 1 is a sample pretreatment device for concentrating trace components contained in a solution sample into an adsorbent,
An adsorption tube insertion portion for inserting an adsorption tube filled with the adsorbent, a gas introduction portion for introducing gas into the adsorption tube, and a syringe insertion portion for inserting a syringe for injecting a sample solution are provided. This is a sample pretreatment apparatus.

  According to a second aspect of the present invention, a large amount of a sample solution is injected into an adsorption tube filled with an adsorbent in the sample pretreatment apparatus, a gas is introduced into the adsorption tube to remove only the solvent, and a trace component is adsorbed. The adsorption tube filled with the adsorbent concentrated to is desorbed from the sample pretreatment device, and the adsorption tube is attached to a heat desorption device for a gas chromatography analyzer, and the adsorption tube is heated and cooled. The adsorbed component adsorbed on the adsorbent for a certain period of time is desorbed to the liner portion, and then the liner portion is rapidly heated to a high temperature to inject and fill the adsorbed component into the column. It is a gas chromatography analysis method characterized by analyzing a trace component contained.

  The present invention is a sample pretreatment apparatus and a gas chromatography analysis method that enable a large amount of sample solution to be injected with high sensitivity to analyze a trace component in a solution with a gas chromatography analyzer. By using the apparatus, 1 ml or more of a solution sample in which a trace component is dissolved can be injected into the adsorption tube. At this time, the solvent is removed, so that the solution sample of 1 ml or more can be used without concern about the influence of the solvent. Can be introduced into a gas chromatography analyzer with heat desorption, and a mass analysis device enables highly sensitive analysis of trace components.

  The measurement method of the present invention will be described in detail below along the embodiments. FIG. 1 shows a cross-sectional view of the pretreatment apparatus of the present invention. This pretreatment apparatus is composed of a part 1 into which an adsorption pipe 9 filled with an adsorbent can be inserted, a part 2 connected to a gas pipe 3, and a removable lid 4. The removable lid 4 has a hole in the center, and a sealing member 5 that can maintain hermeticity is fitted from the back side of the lid.

FIG. 2 shows a cross-sectional view of the adsorption tube 9. The shape and material of the adsorption tube 9 is not limited as long as it is a shape and material that can be introduced into the heat desorption apparatus after the pretreatment, but generally a cylindrical tube is used. A filter 10 is attached to one end of the adsorption tube 9. Since the filter is further filled with an adsorbent, a filter that can be fixed is preferable, and a sintered glass filter is often used. The adsorbent 11 is packed thereon, and the wool agent 12 is packed thereon to fix the adsorbent. As the adsorbent 11, Tenax TA, Tenax GR, activated carbon, graphite carbon black, carbon molecular sieve, or the like is used. It is also possible to fill finely crushed glass or silicon as an adsorbent. It is also preferable to select two types of adsorbents from these and sequentially fill one adsorbing tube. In addition, when a large amount of sample is injected, it is also preferable to select a large-sized adsorption tube and increase the amount of adsorbent to be filled.

  FIG. 3 is a three-dimensional view of the pretreatment devices 1 and 2 before the adsorption tube 9 is attached, and FIG. The 1 adsorption pipe insertion port 7 is shaped so that the adsorption pipe 9 can be accommodated, and it is preferable to fit an O-ring 6 or the like in order to improve the sealing performance between the 1 and the adsorption pipe 9. 1 has a temperature raising function and can be heated. 1 and 2 are separated by a partition, but a hole 8 smaller than the diameter of the adsorption tube 9 is made in the center so that the gas from 3 flows to the portion 7 as indicated by the arrow. To do. 2 is connected to a gas pipe 3. It is preferable that the outer side is a screw type so that the lid 4 can be attached and detached.

  Since the lid 4 is easy to remove and can be used repeatedly, it is preferable to use a screw-type one inside the lid. A hole is opened in the center, and the sealing member 5 is fitted from the back side of the lid 4. FIG. 5 is a diagram showing the lid 4 in a three-dimensional manner, after the sealing member is fitted. The sealing member 5 can be seen from the center of the lid 4. As a sealing member to be used, a general septum having a front / back surface made of rubber / Teflon (registered trademark), silicon / PTFE, or the like is used. In particular, it is preferable to use a septum made of silicon / PTFE because of its high sealing performance when pierced with a syringe.

  A sectional view at the time of actual sample injection is shown in FIG. The adsorption tube 9 filled with the adsorbent 11 is inserted into 1. Insert the filter 10 in the direction in which the filter 10 is clogged first. Next, gas is flowed from 3. At this time, the gas flows from the filter 10 side toward the wool material 12. With the gas flowing, the syringe needle 13 containing the sample solution is inserted through the hole closed by the sealing member at the center of the lid 4 until it hits the sintered glass filter 10 of the adsorption tube 9, and the sample solution is slowly injected. The gas in the sample is removed by sufficiently flowing the gas after the sample is injected. It is also possible to apply a temperature to one part so that the solvent is easily vaporized.

  Even if injection is not performed at once, it is also possible to inject in two or three times. Therefore, there is no restriction on the injection amount. However, when injecting an amount of 1 ml or more, it is desirable to inject it slowly and several times while flowing the gas sufficiently.

  As the gas flowing from 3, an inert gas such as nitrogen or helium is used. To prevent impurities in the gas from adsorbing to the adsorbent, use a high-purity grade, or use an activated carbon filter that removes hydrocarbons, silica gel that removes moisture, and gas that passes through an oxygen trap that removes oxygen. Is preferred.

  The adsorption tube 9 into which the sample has been injected and the gas has been sufficiently removed to remove the solvent is removed from the pretreatment device, attached to a heat desorption device connected to the gas chromatograph / mass spectrometer, and heated at a high temperature in a heating furnace. The adsorption tube is heated, and the adsorbed components are desorbed for a certain period of time on the liner portion cooled with liquid nitrogen or the like. Then, it is heated to a high temperature in a few seconds, sent to a column for separation, and qualitative and quantitative determination is performed with a mass spectrometer.

  The used adsorption tube 9 is slightly lower than the maximum use temperature of the adsorbent 11 and is purged by flowing a purge gas for several hours, and can be used again.

  Hereinafter, the present invention will be described with reference to specific examples, but the technical scope of the present invention is not limited to these examples.

<Example 1>
A multilayer film of vapor deposition film / nylon / aluminum foil / polyethylene was cut into a 5 cm square from the outer surface, immersed in 20 ml of acetonitrile, and allowed to stand for 30 minutes. The film was taken out to obtain an acetonitrile extract.

  An adsorption tube filled with Tenax TA as a filler and sintered glass as a filter was attached to 1, and high-purity nitrogen gas was allowed to flow from 3. Using a syringe for 10 ml, 10 ml of the acetonitrile extract was sucked and inserted from the septum of the lid 4 until it hits the sintered glass of the adsorption tube, and the acetonitrile extract was injected. After flowing nitrogen gas for 10 minutes, the adsorption is attached to a heat desorption device manufactured by Gestel to which a gas chromatograph / mass spectrometer is connected, and heat desorption is performed on a liner portion cooled to −100 ° C. for 10 minutes at 250 ° C. Thereafter, the temperature of the liner portion was raised to 260 ° C. at 12 ° C. per second, and the components were fed into the column to perform a gas chromatograph / mass spectrometer.

<Comparative Example 1>
In Example 1, an inlet liner for liquid was attached to a gas chromatograph / mass spectrometer, and an acetonitrile extract was injected from a 1 μl inlet to perform gas chromatograph / mass spectrometry.

  FIG. 7 shows the total ion chromatogram obtained in Example 1, and FIG. 8 shows the total ion chromatogram obtained in the comparative example. In the method of the comparative example, the detected peak is very small and difficult to detect. Further, since the solvent is injected, the background becomes high. On the other hand, in the method of the example, a chromatogram with good peak sensitivity was obtained. In the method of the embodiment, since the injection amount is 10,000 times, a trace component contained in the solution can also be injected 10,000 times, and the peak sensitivity can be improved.

It is sectional drawing which shows the state by which the adsorption tube was mounted | worn with the sample pretreatment apparatus as one Example of this invention. It is sectional drawing which shows an example of the adsorption tube used for the sample pretreatment apparatus as one Example of this invention. It is a perspective view which shows the principal part of the sample pretreatment apparatus as one Example of this invention. It is sectional drawing which shows the principal part of the sample pretreatment apparatus as one Example of this invention. It is a perspective view which shows an example of the lid | cover used for the sample pretreatment apparatus as one Example of this invention. It is sectional drawing which shows the state which introduce | transduces a sample into the adsorption tube with which the sample pretreatment apparatus as one Example of this invention was mounted | worn. 2 is a total ion chromatogram obtained in Example 1. FIG. 2 is a total ion chromatogram obtained in Comparative Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Adsorption pipe insertion part 2 in a sample pretreatment apparatus ... Gas introduction part 3 in a sample pretreatment apparatus ... Gas piping 4 ... Lid 5 ... Septum 6 ... O-ring 7 ... Adsorption pipe insertion port 8 ... Adsorption of gas Hole 9 for flowing into the tube ... Adsorption tube 10 ... Filter 11 ... Adsorbent 12 ... Wool material 13 ... Needle 14 of syringe ... Syringe

Claims (2)

A sample pretreatment device for concentrating trace components contained in a solution sample into an adsorbent,
An adsorption tube insertion portion for inserting an adsorption tube filled with the adsorbent, a gas introduction portion for introducing gas into the adsorption tube, and a syringe insertion portion for inserting a syringe for injecting a sample solution are provided. Sample pretreatment equipment.   A large amount of sample solution is injected into the adsorption tube filled with the adsorbent in the sample pretreatment device, the gas is allowed to flow into the adsorption tube, only the solvent is removed, and the trace component is concentrated in the adsorbent. The packed adsorption tube is desorbed from the sample pretreatment device, and the adsorption tube is attached to a heating / desorption device for a gas chromatography analyzer, and the adsorption tube is heated, and the adsorption is performed on the cooled liner portion for a predetermined time. The adsorbed component adsorbed on the agent is desorbed, and then the liner is rapidly heated to a high temperature to inject and fill the adsorbed component into the column, and the trace component contained in the solution sample is analyzed by a mass spectrometer. A gas chromatography analysis method characterized by the above.

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