JPH0713623B2 - Atmospheric pressure ionization mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to atmospheric pressure ionization (Atomospherie Pressore).
The present invention relates to an atmospheric pressure ionization mass spectrometer having an ionization function utilizing a molecular reaction such as ionization or ionization, and particularly to an atmospheric pressure ionization mass spectrometer with an improved sample introduction pipe for atomizing a sample or a mobile phase.

[Conventional technology]

A liquid chromatograph directly coupled atmospheric pressure ionization mass spectrometer (hereinafter abbreviated as LC / API mass spectrometer) utilizing atmospheric pressure ionization (hereinafter abbreviated as API) is a conventional electron impact ionization (hereinafter abbreviated as EI) The ionization mechanism uses a gentle ionization means with less impact compared to a gas chromatograph directly coupled mass spectrometer (hereinafter abbreviated as GC / EI mass spectrometer) using It does not decompose when it is used, and it has the feature that molecular ions can be easily observed, and it has many advantages that cannot be obtained by a GC / EI mass spectrometer.

Such an LC / API mass spectrometer guides a sample and a mobile phase eluted from a liquid chromatograph (hereinafter abbreviated as LC) to an atomizing section, and heat is applied in the atomizing section to make the sample into a molecular state. Further, after the sample is ionized by corona discharge in the ionization chamber, mass analysis is performed.

[Problems to be solved by the invention]

However, in the above conventional technique, the atomization part has a diameter of 0.1 m.
The sample introduction pipe having one m hole was integrated with the heater block, and the sample and the mobile phase were atomized by heating the heater block. Therefore, in order to obtain stable and fine atomization, the flow rate of the sample and the mobile phase and the temperature of the heater block have a delicate influence, and the temperature setting of the heater block was very difficult. In the LC / API mass spectrometer, one of the factors for highly sensitive measurement of mass spectrometry is how to stably obtain a finer atomized state of the sample and the mobile phase.

An object of the present invention is to provide an atmospheric pressure ionization mass spectrometer capable of highly sensitive mass analysis by stably obtaining a finer atomized state of a sample and a mobile phase.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention introduces a sample from one end side into a sample introduction pipe by a flow of a mobile phase, and the sample is introduced into the sample introduction pipe by a heating means provided on the outer periphery of the sample introduction pipe. While heating and atomizing,
An atomization unit that ejects the atomized sample from the other end side of the sample introduction pipe, an ionization unit that ionizes the ejected atomized sample under atmospheric pressure, and a mass of the ionized sample In an atmospheric pressure ionization mass spectrometer equipped with a mass spectrometric section for analysis, a plurality of holes for passing the sample and a mobile phase are formed in the sample introducing pipe, and the holes are of the sample introducing pipe. It is characterized in that it is provided along the axial direction.

Further, the plurality of holes provided in the sample introduction pipe are arranged in a circular shape or a radial shape in the cross section of the sample introduction pipe, and the diameter of these holes is formed from 0.01 mm to 0.05 mm.

Further, the sample introduction pipe is inserted into a thin-walled pipe by adhering a plurality of thin rod-shaped bodies in close contact with each other, or a plurality of thin rod-shaped bodies are in close contact with each other, and the outer periphery of the adhered rod-shaped body is made of metal It can be formed by winding a plate.

[Action]

According to the above configuration, by forming a plurality of holes in the sample introduction pipe, it is possible to increase the surface area of the inner surface of the hole as a whole as compared with the case where there is one hole, and the sample and the mobile phase are It is possible to increase the contact area between the sample or the mobile phase and the inner surface of the hole when passing through the inside of the introduction pipe. Therefore, the heat from the heating means can be efficiently transferred to the sample or the mobile phase, and a uniform and fine atomized state can be easily realized. Furthermore, since the heat is efficiently transferred, the temperature gradient inside the hole can be reduced, so the operation to maintain the internal temperature of the hole at the target temperature is extremely easy and stable temperature control is possible. Becomes

Further, in the atmospheric pressure ionization mass spectrometer, it is necessary to eject the atomized sample to the ionization section, but if a plurality of holes are provided along the axial direction of the sample introduction pipe as in the above configuration, It is possible to accurately introduce the atomized sample ejected from the sample introduction pipe into the ionization section.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

The outline of the atmospheric pressure ionization mass spectrometer according to the present invention is shown in FIG. 1. As shown in the figure, the sample and mobile phase eluted from LC1 are sent to the atomization section 3 through the Teflon pipe 2, where the heat is removed. It is atomized by adding. The atomized sample and mobile phase become a molecular state and are ionized by the corona discharge generated from the needle electrode 5 in the ionization chamber 4. The ionized mobile phase molecules undergo a molecular reaction with the sample molecules, ionizing the sample molecules by transferring heptons that have not yet been ionized. By this molecular reaction, the sample molecules are gently and almost all the molecules are ionized. The ionized sample molecules are sent to the mass spectrometric section 8 through the first pore 6 and the second pore 7. , Mass spectrometry.

FIG. 2 shows in detail the configuration from the LC1 to the atomizing unit 3. As shown in the figure, the Teflon pipe 2 for guiding the sample or mobile phase eluted from LC1 is connected to the sample introduction pipe 10 by a joint 9 using a Swedilok screw. The sample introduction pipe 10 is inserted into the heater block 11, and further, the heater block 11 and the sample introduction pipe 10
A spacer 12 for improving heat conduction is attached between the two. A heater 13 for heating the sample introducing pipe 10 and a temperature detecting element 14 for detecting the temperature are attached to the heater block 11 so that an arbitrary temperature and a constant temperature can be applied to the sample or the mobile phase.

The cross section of the sample introduction pipe 10 is formed as shown in FIG. In this embodiment, six holes each having a diameter of 0.04 mm are radially arranged in a ceramic material having an outer diameter of 1.6 mm and a length of 150 mm. This is to minimize the variation of the heat applied from the heater block 11 to each hole. According to this method, when compared with the conventional hole diameter of 0.1 mm, the total cross-sectional area of the hole decreases to 0.96 times, but the surface area of the inner wall of the hole is 2.4 times, and the distance from the inner wall of the hole to the center of the hole Can be 0.4 times. Therefore, when the flow rate from LC1 is set to 0.8 to 1.0 cc / min, the temperature of heater block 11 is 300 to 350 ° C, which is lower than the conventional temperature of 380 to 400 ° C, and stable and fine atomization is achieved. You can get
Moreover, the sensitivity can be improved by 5 to 10 times compared with the conventional one.

In this example, ceramic was used as the material, but this has a function of chemically activating the sample,
It's not always a good idea. However, in the current technology, there is no other method than using ceramics to pass a hole having a diameter of 0.01 to 0.05 mm over a length of 100 to 150 mm. Therefore, it goes without saying that it will be effective if the sample introduction pipe shown in this embodiment can be manufactured using gold (Au) which is the most chemically stable substance in the future.

Further, regarding the arrangement of the holes of this embodiment, an example in which six holes are radially arranged is shown in FIG. 3, but as a method for uniformly applying the heat from the heater block 11 to the sample or the mobile phase, It is also conceivable to arrange several holes in a circle as shown in FIG.

Further, as a method of providing a plurality of fine holes, as shown in FIGS. 5 and 6, a plurality of fine rods made of, for example, stainless are inserted into a thin pipe made of stainless, or a plurality of fine rods are made. It is also possible to manufacture it by winding a fine rod made of, for example, stainless steel with a thin plate made of, for example, stainless steel. However, in the case of this method, it is difficult to intentionally arrange the thin holes as shown in FIG. 3 and FIG. 4, and a random arrangement is made. It may be more difficult than the cases shown in FIGS. 3 and 4.

Further, FIG. 7 shows, for example, a porous metal body or a sintered body inserted in a thin pipe made of stainless steel. In this case, the size of the fine holes can be changed by changing the size of the particles forming the metal body or the sintered body, and more holes can be provided. However, in this way, it is possible to obtain a fine mist, but the sample or mobile phase sprayed from the tip does not always fly straight out toward the sample introduction direction (direction opposite to LC), and some May not enter the ionization chamber.

〔The invention's effect〕

As described above, according to the present invention, the sample can be stably atomized in the atmospheric pressure ionization mass spectrometer, and therefore the sensitivity of mass spectrometry is improved by about 5 to 10 times as compared with the conventional method. It becomes possible. As a result, the sensitivity of the LC / API mass spectrometer can be easily adjusted, and the analytical operation is very easy.

[Brief description of drawings]

FIG. 1 is a schematic view of an LC / API mass spectrometer, FIG. 2 is a detailed view of a sample introduction pipe, FIG. 3 is a cross sectional view of the sample introduction pipe of the present invention, and FIG. 4 is a cross section showing a modification thereof. FIG. 5, FIG. 6, FIG. 6 and FIG. 7 are cross-sectional views showing another embodiment in which the sample introducing pipe is provided with a plurality of holes. 1 ... Liquid chromatograph, 3 ... Atomization section, 4 ... Ionization chamber, 5 ... Needle electrode, 8 ... Mass analysis section, 10 ... Sample introduction pipe, 11 ... Heater block, 12 ... Spacer , 13 ... Heater, 14 ... Temperature detection element.

Claims (5)

[Claims] 1. A sample is introduced into a sample introducing pipe from one end side by a flow of a mobile phase, and the sample is heated in the sample introducing pipe by a heating means provided on the outer periphery of the sample introducing pipe to atomize the sample. , An atomizing part for ejecting the atomized sample from the other end side of the sample introducing pipe, an ionizing part for ionizing the ejected atomized sample under atmospheric pressure, and a mass of the ionized sample In an atmospheric pressure ionization mass spectrometer comprising: a mass spectrometric section for analyzing the sample introduction pipe, a plurality of holes for passing the sample and a mobile phase are formed in the sample introduction pipe, and the holes are the sample introduction pipe. An atmospheric pressure ionization mass spectrometer characterized in that it is provided along the axial direction of. 2. The atmospheric pressure ionization mass spectrometry according to claim 1, wherein the plurality of holes formed in the sample introduction pipe are arranged in a circular shape or a radial shape in a cross section of the sample introduction pipe. Total. 3. The atmospheric pressure ionization mass spectrometer according to claim 1, wherein the plurality of holes formed in the sample introduction pipe have a diameter of 0.01 mm to 0.05 mm. 4. The atmospheric pressure ionization mass spectrometer according to claim 1, wherein the sample introduction pipe is formed by inserting a plurality of thin rod-shaped bodies in close contact with each other in a thin-walled pipe. 5. The sample introducing pipe according to claim 1, wherein a plurality of thin rod-shaped bodies are adhered to each other, and a metal plate is wound around the outer periphery of the adhered rod-shaped bodies. Atmospheric pressure ionization mass spectrometer.