JP2780291B2 - Liquid chromatograph / mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a liquid chromatograph / mass spectrometer (LC-M
S) particularly relates to an interface provided between the liquid chromatograph and the mass spectrometer.

(Prior art) Liquid chromatographs are used for the separation and analysis of complex mixed systems such as biological substances. In recent years, liquid chromatographs have been directly connected to mass spectrometers that are excellent in qualitative analysis. Liquid chromatographs / mass spectrometers that separate mixed samples and perform qualitative analysis using mass spectra have become widely used.

Liquid chromatography uses a liquid mobile phase. In order to separate the mobile phase of the liquid into which this sample has been injected by a column and analyze the separated component solution with a mass spectrometer, the solution is gasified and ionized, and the resulting ions are introduced into the mass spectrometer. Interface is required, but the mass spectrometer requires a high vacuum, so the interface is a complicated method for introducing a solution under atmospheric pressure into the mass spectrometer while maintaining the high vacuum of the mass spectrometer. Structure is required. Conventionally, as this interface, for example, a thermospray interface that sprays a sample together with a mobile phase into a sample ionization chamber by a vaporizer to vaporize and ionize the sample is widely used. Because the mobile phase is in a vacuum state and a gasified mobile phase is also introduced into the mass spectrometer, the gas in the mobile phase contaminates the pre-lens system and mass separation part of the mass spectrometer, lowering the sensitivity of the mass spectrometer And problems such as reduced resolution. Such a problem exists not only in the thermospray interface but also when other ionization methods are used in LC-MS.

(Problems to be Solved by the Invention) An object of the present invention is to prevent a lens and a mass separation unit of a mass spectrometer from being contaminated by a mobile phase.

(Means for solving the problems) In a liquid chromatograph / mass spectrometer, the detection means for detecting the sample component eluted from the LC column and the inlet to the mass spectrometer from the interface of the liquid chromatograph / mass spectrometer An opening / closing means for opening and closing, and a control means for controlling the opening / closing means based on a detection signal of the detection means to open / close the introduction port are provided.

(Function) Since the sample components separated by LC move intermittently from the column to the ionization chamber, it is unnecessary to keep the inlet from the ionization chamber to the mass spectrometer always open. Since the gas of the phase enters the inside of the mass spectrometer and contaminates the lens and the mass separation unit, the present invention detects that the sample component has flowed out of the column, and the sample component is introduced into the ionization chamber. By opening the inlet only when ionized, an attempt is made to prevent a mobile phase unrelated to the measurement from unnecessarily entering the mass spectrometer.

(Example) FIG. 1 shows an example of the present invention. In the figure, 1 is a pump for discharging the mobile phase solvent used for transporting the sample, 2 is an injector for injecting the sample into the mobile phase solvent, 3 is a column for chromatographic separation of the sample, 4 is a detector for chromatography, and column A part of the sample separated in 3 may be separated to detect each component, or the column effluent may be entirely passed through the detector 4 as in this embodiment. Absorption spectroscopy is a detection means suitable for such a total flow. The liquid chromatograph LC is composed of the above-mentioned pump 1, injector 2, column 3, and chromatographic detector 4, and separates a sample into components and detects the separated components. Reference numeral 5 denotes a vaporizer that sprays the sample separated by the column 3 into the ionization chamber 6 and vaporizes and ionizes the sample. Reference numeral 7 denotes an inlet for introducing ions from the ionization chamber 6 into the mass spectrometer MS.
The orifice 7A is provided at the tip, and the inlet 7A protrudes into the ionization chamber 6. 7 is the above inlet 7A
The plate is opened and closed by a plate driving unit 9 controlled by a detection signal of the detector 4. Reference numeral 10 denotes a rotary pump RP for evacuating the ionization chamber 6 and removing an extra mobile phase. Reference numeral 11 denotes a lens that accelerates and converges ions passing through the orifice 7, and 12 denotes a quadrupole mass separation unit that mass separates the introduced ions. 13 is a turbo pump for evacuation of the mass spectrometer MS, 14 is a secondary electron multiplier for detecting mass separated ions,
A data processing unit 15 processes the detection signal obtained by the multiplier 14.

The measurement operation in the above embodiment will be described. A fixed amount of mobile phase solvent is discharged from the pump 1, and a sample is injected into the mobile phase solvent in the injector 2 and sent to the column 3.
The solution sent to the column 3 is separated for each component, the components are sequentially detected by the detector 4 for chromatography, and are sprayed into the ionization chamber 6 by the vaporizer 5 to be ionized. The plate 8 usually covers the inlet 7A of the orifice 7,
Only when the detection signal of the detector 4 becomes a certain value or more, the plate driving unit 9 raises the plate 8 in accordance with the timing at which the sample ion corresponding to the detection signal reaches the introduction port 7A, and moves the introduction port 7A. Open. When the sample ions whose detection signals show a certain value or more pass, the plate 8 is lowered to cover the inlet 7A with the plate 8. The sample ions passing through the inlet 7A are mass-separated by the mass separation unit 12, and the ions mass-separated by the multiplier 14 are detected. Inlet 7A
Gases that do not pass through are exhausted by RP10. The detection signal detected by the multiplier 14 is processed by the data processing unit 15, and the mass spectrum is displayed on a display unit (not shown).

In the above embodiment, the plate driving unit 9 is directly driven by the detection signal of the chromatographic detector 4. However, in general, a CPU is used in the data processing unit 9, and all data processing is performed by the CPU. Therefore, in the above embodiment, the signal for controlling the plate driving unit 9 is also transmitted to the CPU.
Then, the detection signal from the detector 4 may be compared with a reference value, and when the detection signal exceeds the reference value, the CPU may set a predetermined delay time and transmit it to the plate driving unit 9.

(Effect of the Invention) According to the present invention, only when sample ions are generated,
By opening the inlet of the orifice, the mobile phase does not enter the mass spectrometer more than necessary, so contamination of the lens and mass separation part is reduced, resulting in lower sensitivity and resolution. Was able to be prevented from decreasing.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention. 1 ... pump, 2 ... injector, 3 ... column,
4. Chromatographic detector, 5 ... Vaporizer,
6 ... ionization chamber, 7 ... orifice, 8 ... plate, 9 ... plate drive unit, 10 ... rotary pump (RP), 11 ... lens, 12 ... mass separation unit, 13 ... turbo pump, 14 …… Multiplier (ion detector),
15 Data processing unit.

Claims (1)

(57) [Claims] 1. A detecting means for detecting a sample component eluted from an LC column, an opening / closing means for opening / closing an inlet to a mass spectrometer from an interface of a liquid chromatograph / mass spectrometer, and a detection signal from the detecting means. A liquid chromatograph / mass spectrometer, further comprising control means for controlling the opening and closing means to open and close the inlet.