JPH0729542A - Mass spectrometer - Google Patents

Abstract

(57) [Summary] [Structure] The spray gas guide 5 made of an insulator is the ion source 3
Is installed at the tip of the spraying capillary 4. [Effect] With the spray gas guide, since the spray gas does not spread spatially, the reaction efficiency of the gas phase ionic molecule reaction is increased. Therefore, the detection sensitivity of the pseudo-molecular ion generated by the gas-phase ion-molecule reaction becomes high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mass spectrometer, and more particularly to a liquid chromatograph / mass spectrometer (LC / MS) and a capillary electrophoresis / mass spectrometer (CE / MS) capable of separating and analyzing biological substances. .

[0002]

2. Description of the Related Art International Journal of Mass Spectrometry and Ion Processes 120 (1992), pages 207 to 216 (Int
er-national Journal of Mass Spectrometry and Ion P
rocesses 120 (1992) pp207-216),
There is a description using an atmospheric pressure spray method ion source consisting of a heatable spray capillary. However, the tip of the spray capillary is bare.

[0003]

In the above-mentioned prior art, since the spray gas emitted from the tip of the spray capillary spreads spatially due to diffusion, the ions of the sample molecules in the spray gas are introduced into the ion intake port of the mass spectrometer. The rate of loss is not negligible.

When the deposit grows at the tip of the spray capillary, the direction of the spray gas is inclined. When this angle is large, the amount of ions of the sample molecules introduced into the ion intake port of the mass spectrometer is drastically reduced, and the detection sensitivity of the device is lowered.

The object of the present invention is to provide a liquid chromatograph / mass spectrometer (LC / MS) or capillary electrophoresis / capillary electrophoresis capable of detecting ions of sample molecules in a spray gas produced from a heatable spray capillary with high sensitivity and stability. It is to provide a mass spectrometer (CE / MS).

[0006]

A spray gas guide is provided at the tip of the spray capillary in order to efficiently introduce the ions in the spray gas emitted from the tip of the spray capillary into the mass spectrometer ion intake port.

Further, even if the direction of the spray gas emitted from the spray capillary is inclined, the ions contained in the spray gas are stably introduced into the mass spectrometer ion intake port and detected, so that the spray is sprayed at the tip of the spray capillary. A gas guide is provided.

[0008]

When the spray gas generated at the tip of the spray capillary is introduced into the spray gas guide having a small inner diameter, the spray gas is prevented from being diffused spatially. Therefore, by installing a mass spectrometer ion intake port in the vicinity of the spray gas guide outlet, the ions generated by atomization or gas phase ion molecule reaction are effectively introduced into the mass spectrometer, and high-sensitivity detection is realized. .

When the direction of the spray gas is inclined by the angle θ,
If the following relationship holds between the distance L between the tip of the capillary and the ion inlet of the mass spectrometer and the inner diameter D of the gas guide, the spray gas collides with the inner surface of the gas guide at least once, so The moving direction of the particles approaches a direction parallel to the central axis of the gas guide.

[0010]

## EQU1 ## D ≦ 2L tan θ (Equation 1) From Expression 1, for example, when L = 10 mm and θ = 5 °, D ≦ 1.7 mm. Therefore, even if the spray gas is inclined by an angle θ or more, the amount of ions introduced into the mass spectrometer ion intake port hardly changes, and the ions can be detected stably. The spray gas flow is turbulent, so the spray direction is θ = 5 °
Even if tilted to some extent, the amount of ions introduced into the mass spectrometer ion intake port hardly changes.

[0011]

EXAMPLE FIG. 1 shows an explanatory view of a liquid chromatograph / mass spectrometer (LC / MS) according to an example of the present invention. The sample solution separated by the liquid chromatograph (LC) 1 passes through the pipe 2 and the spray capillary 4 of the ion source 3.
Will be introduced to. The atomizing gas generated by the atomizing capillary 4 is introduced into the atomizing gas guide 5 at the tip of the atomizing capillary 4, and then introduced into the mass spectrometer 6. The ions contained in the atomizing gas are then mass separated. The inner diameter of the atomizing gas guide 5 almost coincides with the outer diameter of the atomizing capillary 4. In addition, capillary electrophoresis / mass spectrometry (CE /
In MS), a capillary electrophoresis device is used instead of the liquid chromatograph (LC) 1 and the pipe 2. The ion source peripheral part is common.

FIG. 2 shows a sectional view of an embodiment of an ion source using a cartridge heater. The spray capillary 4 brazed with silver on the metal block 7 is heated by the cartridge heater 8 held on the metal block 7. The thermocouple 9 welded to the tip of the spray capillary 4 monitors the temperature of the tip of the spray capillary 4 and controls the current value flowing through the cartridge heater 8 based on the temperature. Since the atomizing gas guide 5 is fixed to the metal block 7 with screws, it can be easily attached and detached. Spraying capillary 4
If the deposit grows extremely at the tip of the, the deposit can be easily removed by removing the spray gas guide 5. The thermocouple 9 is also fixed by the spray gas guide 5. Therefore, an unnecessary force is externally applied to the welding point of the thermocouple 9 with the spray capillary 4, and the thermocouple 9 can be prevented from coming off the spray capillary 4.

FIG. 3 shows a sectional view of the ion source of the second embodiment using a cartridge heater. Spray gas guide 5
Since the inside of the is tapered, the spray gas flow is disturbed immediately after spraying. Therefore, vaporization of the charged droplets and gas phase ion molecule reaction are promoted.

FIG. 4 shows a sectional view of an ion source of a third embodiment using a cartridge heater. The metal block 7 is divided into one for heating the spray capillary 4 and one for heating the spray gas guide 5. The atomizing gas guide 5 has an inner diameter of 1.7 mm and a length of 100 mm, but only the tip has an inner diameter of 1 mm. Since the atomizing gas guide 5 is heated,
Even if droplets or charged droplets are generated from the spraying capillary 4, they pass through the spraying gas guide 5 and the evaporation of solvent molecules is promoted. Therefore, the detection sensitivity of sample molecules or pseudo-molecular ions is improved. Corona discharge electrode 10
3-6k between the mass spectrometer ion intake port 11 and the mass spectrometer
A voltage of about V can be applied, and corona discharge can be generated. When a corona discharge is generated, the neutral sample molecules generated by the spray generate ions (N ₂ +,
Owing to collisions with O ₂ +, H ₃ O + and its water clusters (gas phase ion molecule reaction), they are ionized to generate pseudo molecular ions (atmospheric pressure chemical ionization method). These ions are introduced into the mass spectrometric section through the mass spectrometer ion intake port 11 and are mass separated. Since the inner diameter of the tip of the atomizing gas guide 5 is small, high-density sample molecules are released from the atomizing gas guide 5, so that the ionization efficiency is increased and the detection sensitivity of pseudo-molecular ions is improved.

FIG. 5 shows a sectional view of the ion source of the fourth embodiment using a cartridge heater. Spray gas guide 5
Immediately after the above, a vaporizer 12 is installed to promote vaporization of droplets or charged droplets.

[0016]

The atomizing gas discharged from the tip of the atomizing capillary is not spatially diffused by the atomizing gas guide of the present invention. Therefore, pseudo-molecular ions of sample molecules can be introduced into the mass spectrometer ion intake port at high density, and high-sensitivity detection can be realized.

Further, even if the direction of the spray gas generated from the spray capillary is inclined, the amount of pseudo-molecular ions introduced into the mass spectrometer ion intake port by the spray gas guide of the present invention hardly changes. Therefore, the ions can be stably detected without depending on the direction of the spray gas.

In the spray gas guide of the present invention, since the density of ions and neutral sample molecules in the spray gas is high, the reaction efficiency of the gas phase ion molecule reaction is high. Therefore, the detection sensitivity of the pseudo molecular ion generated by the gas phase ion molecular reaction is high.

Further, the spray gas guide of the present invention rarely mixes the impurity gas existing around the ion source and is ionized by the gas phase ion molecule reaction. Therefore, the detection sensitivity of the sample molecule is prevented from being lowered due to the mixture of the impurity gas.

Further, it is possible to prevent the temperature of the spray capillary from being lowered due to a part of the spray gas being reflected near the ion intake port of the mass spectrometer and hitting the spray capillary.

[Brief description of drawings]

FIG. 1 Liquid chromatograph / mass spectrometer (LC / M
Explanatory drawing of S).

FIG. 2 is a sectional view of an embodiment of a spray ion source using a spray gas guide.

FIG. 3 is a cross-sectional view of a second embodiment of a spray ion source using a spray gas guide.

FIG. 4 is a cross-sectional view of a third embodiment of a spray ion source using a spray gas guide.

FIG. 5 is a cross-sectional view of a fourth example of a spray ion source using a spray gas guide.

[Explanation of symbols]

1 ... Liquid chromatograph, 2 ... Piping, 3 ... Ion source, 4
… Spray capillaries, 5… spray gas guides, 6… mass spectrometers.

Claims (7)

[Claims] 1. A separation means for separating a mixed sample in a solution,
An ion source that converts a sample in the solution into gaseous ions by a heatable spray capillary, a mass separation unit that mass-separates the ions generated by the ion source in a high vacuum, and a mass-separated ion A mass spectrometer having a detecting means for detecting, wherein a tubular spray gas guide is installed at the tip of the spray capillary. 2. The mass spectrometer according to claim 1, wherein the atomizing gas guide of the ion source has an inner diameter of 0.5 to 4 mm and a length of 3 mm or more. 3. The mass spectrometer according to claim 2, wherein the inner surface of the atomizing gas guide is made of an insulator such as ceramic or glass. 4. The mass spectrometer according to claim 3, wherein the atomizing capillary of the ion source and the atomizing gas guide are different from each other, and the atomizing gas guide is removable. 5. The mass spectrometer according to claim 4, wherein the atomizing gas guide of the ion source is in close contact with the atomizing capillary, and inflow of gas from the surroundings is ignored. 6. The mass spectrometer according to claim 5, wherein the atomizing gas guide of the ion source is heatable. 7. The mass spectrometer according to claim 6, wherein the inner surface of the atomizing gas guide of the ion source is tapered and the inner diameter is not constant.