JPS6120859A - Mass spectrometer by gas chromatograph using gaseous hydrogen carrier - Google Patents

Abstract

PURPOSE:To permit microanalysis with high resolution and sensitivity by removing a gaseous hydrogen carrier, diluting and introducing the same together with a diluted and ionized sample component into an ionization chamber. CONSTITUTION:An org. compd. which has a high b.p. and high mass and is a sample is injected into a sample evaporating chamber 3 where the sample is evaporated. The evaporated sample is introduced together with the gaseous hydrogen carrier fed from a vessel 1 into a separating column 4. The separated and eluted sample component and the gaseous hydrogen carrier are discharged in the form of jet flow from a discharge pipe 5a of a jet separator 5. The gaseous hydrogen carrier is thereupon easily separated from the jet flow by the evacuation effect of a vacuum pump connected to the gaseous hydrogen carrier discharge pipe 5c of the separator 5. The sample molecules having the heavy mass are introduced through an introducing pipe 5b into the ionization chamber 7 without being separated. About two-fold higher rate of removing the gaseous carrier proportional inversely to the mass is obtd. as compared with the case of using helium if hydrogen is used as the gaseous carrier in the above-mentioned manner.

Description

Detailed Description of the Invention (a) Field of Industrial Application The invention related to this application relates to a gas chromatograph mass spectrometer using a hydrogen carrier gas for analyzing, for example, high-boiling point, high-mass organic compounds. It is related to.

(b) Prior Art A gas chromatograph mass spectrometer is a complex analyzer that performs separation analysis of a sample using a gas chromatograph with excellent separation ability, and mass spectrum analysis of separated sample components.

This gas chromatograph mass spectrometer has the following problems. In other words, when performing sample separation analysis using a gas chromatograph alone, it is possible to obtain a sharp peak waveform by introducing a carrier gas such as helium at an optimal flow rate into the separation column, but when the gas chromatograph is connected to a mass spectrometer, it is possible to obtain a sharp peak waveform. Then, the optimum flow rate of the jet separator connected between the separation column and the ionization chamber of the mass spectrometer does not match that of the separation column, and therefore the flow rate of the carrier gas is adjusted to the optimum flow rate of the separation column of the gas chromatograph. When set, the carrier gas removal rate of the jet separator decreases, and excess carrier gas molecules exist in a neutral state in the ionization chamber of the mass spectrometer.

The frequency of elastic scattering between excess carrier gas molecules existing in a neutral state and ionized sample molecules increases,
This causes variations in the initial velocity Δ■ of ionized sample molecules and a broadening of the ion exit angle.

For example, when analyzing high-boiling point, high-mass organic compounds such as triglycerides, sterol esters, and oligosaccharides using a gas chromatograph mass spectrometer, the carrier of the separation column of the gas chromatograph is In addition to setting the gas flow rate to the optimum flow rate for the jet separator, it is also possible to compensate for the decrease in separation capacity due to a decrease in the carrier gas flow rate by increasing the heating temperature of the separation column. The background increases when
Eventually, the separation ability will deteriorate.

Figures 4 to 6 show the removal effect of the carrier gas, which is helium, by the jet separator of such a conventional device, the variation in the initial velocity △■ of ionized sample molecules in the ionization chamber, and the spread p of the ion exit angle. I will explain it to you.

FIG. 4 shows a cross section of the jet separator.

In the figure, the jet separator 5 includes a gas chromatograph side discharge pipe 5α connected to a separation column (not shown) of the gas chromatograph, a mass spectrometer side inlet pipe 5b, and a carrier gas discharge pipe connected to a vacuum pump (not shown). 5C
All of these are constructed from Pyrex glass.

FIG. 5 schematically shows the removal action of carrier gas within the jet separator.

In the figure, a carrier gas of helium, indicated by a white circle, and a sample component layer, indicated by a large black circle, are discharged as a jet stream from the gas chromatograph side discharge pipe 5α. Since the jet separator is evacuated by a vacuum pump (not shown), carrier gas having a light mass compared to the mass of the sample components is separated from the carrier gas and sample molecules, which are discharged as a jet stream. . Then, the K-concentrated sample molecules and carrier gas are introduced into the mass spectrometer side introduction tube 5'b.

Now, the carrier gas removal rate of the jet separator is when the carrier gas is helium, the flow rate is 30 ml.
l The best setting is from 7 minutes to 40 m#/minute,
When the carrier gas flow rate is increased from the above value,
The removal rate of the carrier gas is reduced, resulting in the introduction of excess carrier gas into the ionization chamber.

FIG. 6 schematically shows the spread of the initial velocity Δ■ of ionized sample molecules in the ionization chamber and the spread of the ion exit angle.

In the same figure, the jet separator side or the ionization chamber 7
The electron beam e- introduced into the filament 61 and emitted from the filament 61 passes through the entrance hole 7α and collides with the sample molecules,
Ionize. ■marks indicate ionized sample molecules;
The small open circles indicate carrier gas molecules, which are helium.

The electron beam e emitted from the filament 61 passes through the electron beam exit hole 7b and reaches the collector 62. As mentioned above, in the ionization chamber 7, the carrier gas in the neutral state is excessively present in the molecular state, so the frequency of collision between the ionized sample molecules and the carrier gas molecules, and even the frequency of elastic scattering, becomes very high. Momentum possessed by gas molecules and that possessed by ionized sample molecules are frequently exchanged with each other, resulting in large variations in the initial velocity ΔV of ionized sample molecules. Since the excess carrier gas molecules in the neutral state and the ionized sample molecules are still emitted from the ion exit hole 7C of the ionization chamber while exhibiting an elastic scattering phenomenon with each other, the ion exit angle θ1 widens.

For this reason, there is a problem in that the obtained mass spectrum waveform is broadened, resulting in a decrease in resolution and sensitivity, making it difficult to perform trace analysis.

(c), Purpose The invention related to this application is to eliminate the drawbacks of the prior art described above, and the first invention is to separate and elute sample components together with the removed and diluted hydrogen carrier gas. It is an object of the present invention to provide a gas chromatograph mass spectrometer that can be incorporated into a mass spectrometer and perform microanalysis with high resolution and sensitivity, and the second invention is a means for achieving the object of the first invention. It is an object of the present invention to provide a gas chromatograph mass spectrometer equipped with a large-diameter capillary column as a part.

), Structure The first invention of this application is a hydrogen carrier gas supply source that supplies a hydrogen carrier gas, a sample vaporization chamber into which the hydrogen carrier gas of the hydrogen carrier gas supply source is introduced, and a vaporization chamber from the sample vaporization chamber. a separation column into which a separated sample and a hydrogen carrier gas are introduced; a hydrogen carrier gas means into which sample components separated and eluted from the separation column and the hydrogen carrier gas are introduced; and a hydrogen carrier gas means for removing the hydrogen carrier gas; A gas chromatograph mass spectrometer equipped with an ionization chamber for ionizing components, which removes the hydrogen carrier gas by a hydrogen carrier gas removal means and eliminates variations in the initial velocity ΔV of sample molecules ionized in the ionization chamber. The second invention of the application is a hydrogen carrier that supplies a hydrogen carrier gas. A gas supply source, a sample vaporization chamber into which the hydrogen carrier gas of the hydrogen carrier gas supply source is introduced, a large-diameter capillary column into which the vaporized sample from the sample vaporization chamber and the hydrogen carrier gas are introduced, and this capillary column. A gas chromatograph mass spectrometer equipped with an ionization chamber that ionizes the sample components separated and eluted from the column) ionizes the sample separated and eluted from the large-diameter capillary column, and calculates the initial velocity of the ionized sample molecules △■ 〇 (e) In the following Examples, the first invention of this application and the An example of a gas chromatograph mass spectrometer according to the second invention will be described.

FIG. 1 shows a system diagram of an embodiment of the first invention of this application.

In the figure, hydrogen carrier gas is introduced into a sample vaporization chamber 3 via a conduit 2 from a container 1 filled with hydrogen carrier gas. In the sample vaporization chamber 3, a high boiling point, high mass organic compound as a sample is injected from a direction indicated by an arrow using a microsyringe (not shown), vaporized, and introduced into the separation column 4 together with a hydrogen carrier gas. This separation column 4 is intended to analyze high-boiling-point, high-mass organic compounds, so the length is 15 m to 20 cm, and the liquid phase has a low concentration of about 1% to 1.5%, and the column temperature is kept low. In addition to setting the hydrogen carrier gas flow rate to about 70m.
1 liter for 1 minute to 90 ml for 1 minute. The sample components separated and eluted from the separation column 4 and the hydrogen carrier gas are discharged as a jet stream from the gas chromatograph side discharge pipe 5a of the jet separator 5.

FIG. 2 schematically shows a state in which hydrogen carrier gas is removed and sample molecules are concentrated in, for example, a jet separator that functions as a hydrogen carrier gas removal means used in the embodiment of the first invention of this application. It is something that

In the same figure, hydrogen carrier gas H is indicated by a small black circle.
2 and sample molecules m indicated by large black circles are discharged in a jet stream from the gas chromatograph side discharge pipe 5α. Since the mass of hydrogen is lighter than that of helium, which is 2, the hydrogen carrier gas discharge pipe 5 of the jet separator 5
The hydrogen carrier gas is easily separated from the jet stream by the evacuation action of the vacuum pump connected to c, and the heavier sample molecules m are introduced into the introduction tube 5b on the mass spectrometer side without being separated. In this introduction pipe 5b, the removed and diluted hydrogen carrier gas and the concentrated sample molecules m
The two coexist, proceed in the direction of the arrow, and are introduced into the ionization chamber 7 of the ionization device 6.

When hydrogen is used as a carrier gas in this manner, it is possible to obtain a carrier gas removal rate, in other words, a dilution rate that is approximately twice as high as inversely proportional to the mass of helium, compared to when helium is used.

Now, the hydrogen carrier gas is well removed and diluted in the jet separator, and introduced into the ionization chamber 7 together with the sample molecules m, where they are ionized. Reducing the variation in the initial velocity ΔV of ionized sample molecules and preventing the ion exit angle from widening will be explained.

In the figure, hydrogen carrier gas and sample molecules indicated by black circles are introduced into the ionization chamber 7 through the jet separator side. An electron beam e- is emitted from the filament 31, enters the ionization chamber 7 through the electron beam entrance hole 7α, collides with the sample molecules, and ionizes the sample molecules as shown by the symbol ■. The light enters the collector electrode 32 through the beam. Note that for the sake of simplicity of explanation, it is assumed that only sample molecules are ionized.

Normally, in a gas chromatograph mass spectrometer, the variation in the initial velocity Δ■ of ions in the ionization chamber 7 and the spread of the ion exit angle at the ion exit hole 7C are as follows.
It is said that this is related to the amount and type of carrier gas introduced. Therefore, the amount of hydrogen carrier gas present in the ionization chamber 7 is reduced, and the mass of hydrogen is half that of helium. Therefore, the frequency of collisions between hydrogen carrier gas molecules existing in a neutral state and ionized sample molecules, and thus the frequency of elastic scattering, are reduced. The momentum, which is the product of the mass and velocity of the hydrogen carrier gas in the neutral state, is compared with that of helium when the velocities are the same; since the mass of hydrogen is half that of helium, It becomes half. Therefore, when ionized sample molecules collide with hydrogen carrier gas molecules in a neutral state, the transfer of momentum between the ionized sample molecules is half that of helium.

In this way, due to both the reduction in the frequency of collisions between ionized sample molecules and hydrogen carrier gas molecules in a neutral state and the light mass of hydrogen, variations in the initial velocity ΔV of ionized sample molecules are reduced. In addition, when ionized sample molecules and hydrogen carrier gas molecules in a neutral state are emitted from the ion exit hole 7c of the ionization chamber 7, a good removal rate of the hydrogen carrier gas, dilution, and hydrogen Because of the light mass it has, the frequency of collisions is low, and as a result, elastic scattering is low, and therefore the ion exit angle θ2 of ionized sample molecules from the ion exit hole 7c can be prevented from widening.

The ionized sample molecules emitted from the ion exit hole 7c are introduced into the magnetic field scanning device 10 (a quadrupole mass spectrometer may be used) through the analysis tube 9, and subjected to magnetic field scanning.
The mass is separated, inputted into an electron multiplier 11, converted into an electric current, and inputted into a recording device 12, where a mass spectrum waveform is recorded.

Next, an embodiment of the second invention of this application will be described.

Referring to FIG. 1, for example, a jet separator 7 is provided between the separation column 4 and the ionization chamber 7 as a means for removing and diluting the hydrogen carrier gas. However, by using a means with a dilution function, it is possible to reduce the variation in the initial velocity ΔV of ionized sample molecules in the ionization chamber and to prevent the ion exit angle from widening at the ion exit hole. .

For this purpose, a large diameter capillary column can be cited as a means having the same function as the means for removing and diluting the hydrogen carrier gas.

The diameter of the large diameter capillary column is between 0.2 mm and 0.2 mm.
25+ m, and the flow rate of the hydrogen carrier gas supplied thereto is about 3 m11 min to 5 mil/min,
This is much smaller than the hydrogen carrier gas flow rate of 70 m1/min to 90 m11 min described in the detailed description of the first invention of this application. Therefore, even if the sample components separated and eluted from the large-diameter capillary column and the hydrogen carrier gas are directly introduced into the ionization chamber 7, the amount of hydrogen carrier gas present in the ionization chamber 7 is small. This is similar to the case where the hydrogen carrier gas is removed at Output hole 7C
It is possible to prevent the ion emission angle of ionized sample molecules emitted from the ion beam from widening.

In the description of the first invention and the second invention of this application mentioned above, organic compounds with a high boiling point and high mass are mentioned as the analysis target, but other organic compounds which are not limited to high boiling points and high mass can also be used. and hydrocarbons can also be analyzed.

(f) Effects As explained above, according to the first invention of this application, the hydrogen carrier gas can be effectively removed using a means for removing and diluting the hydrogen carrier gas, and the sample is diluted and vaporized. Since it is configured to be introduced into the ionization chamber together with the components,
Initial velocity Δ■ of ionized sample components in the ionization chamber
It is possible to reduce the variation of According to the second invention of this application, by configuring a large-diameter capillary column to be directly connected to the ionization chamber in place of a normal separation column, it is possible to perform trace analysis. It reduces the variation in the initial velocity ΔV of ionized sample molecules, prevents the ion exit angle of the ionized sample molecules from the ion exit hole from widening, and prevents the mass spectrum waveform from spreading after mass separation. prevention, increase resolution, and perform trace analysis.

1 to 3 illustrate the invention related to this application. FIG. 1 is a system diagram of an embodiment of a gas chromatograph mass spectrometer according to the first invention of this application, and FIG. 1
Figure 3 is an explanatory diagram schematically showing the state of dilution by removing hydrogen carrier gas from a mixture of hydrogen carrier gas and sample molecules in the jet separator used in the apparatus shown in the figure. 4 to 6 are explanatory diagrams schematically showing the variations in the initial velocity ΔV of ionized sample molecules in the ionization chamber used in the first invention and the second invention and the spread of the ion exit angle. The figures explain a conventional device, and Fig. 4 is a cross-sectional view of a jet separator, and Fig. 5 shows how helium carrier gas is removed from a mixture of carrier gas and sample molecules when helium is used as a carrier gas. FIG. 6 is an explanatory diagram schematically showing the state of the spread of the initial velocity ΔV of ionized sample molecules in the ionization chamber and the spread of the ion exit angle.

In the figure, 1 is a hydrogen carrier gas container, 2 is a conduit, 3 is a sample vaporization chamber, 4 is a separation column, 5 is a jet separator, 5α is an exhaust pipe on the gas chromatograph side, 5b is an inlet pipe on the mass spectrometer side, 5C is a carrier gas discharge pipe, 6 is an ionization device, 7 is an ionization chamber, 7α is an electron beam entrance hole, 7
b is an electron beam exit hole, 7C is an ion exit hole, 8 is an acceleration electrode, 9 is an analysis tube, 10 is a magnetic field scanning device, 11 is a recording device, 31 is a filament for emitting electrons, 32 is a collector electrode, m is the sample molecule, θ, and 02 are the ion exit angles.

Figure 1 of Figure 2 Figure 3 Figure 4 and others

Claims (3)

[Claims] (1) a hydrogen carrier gas supply source, a sample vaporization chamber connected to the supply source, a separation column connected to the sample vaporization chamber, and a hydrogen carrier gas supply source connected to the separation column for removing the carrier gas; A gas chromatograph mass spectrometer comprising a carrier gas removal means and an ionization chamber connected to the removal means. (2) The gas chromatograph mass spectrometer according to claim 1, wherein the hydrogen carrier gas removal means is a jet separator. (3) A gas chroma system comprising a hydrogen carrier gas supply source, a sample vaporization chamber connected to the supply source, a large-diameter capillary column connected to the sample vaporization chamber, and an ionization chamber connected to the column. tograph mass spectrometer.