JPH0830695B2 - Liquid chromatograph / mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a liquid chromatograph / mass spectrometer (LC-M).
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(Prior Art) Time-of-flight mass spectrometry is based on the energy provided by the applied voltage and the charge of the ions, and when the ions are simultaneously accelerated, the larger the mass, the smaller the acceleration speed, Is used to analyze the mass of an ion by the time it takes for the ion to reach the detector. Therefore, it is necessary to accelerate the ions simultaneously and in a pulsed manner (intermittently). However, the laser irradiation ionization method is used as a method capable of such pulse ionization method. However, the laser ionization method has a problem that a sample that can be ionized is limited.

On the other hand, in LC-MS, as a method of ionizing the sample (outflow solution), after the outflow solution is vaporized, an electron impact ionization method in which electrons emitted from the filament collide with sample gas molecules, a voltage applied electrode tip There is also a discharge ionization method in which ionization is performed by a corona discharge formed in 1. However, since such an ionization method continuously performs ionization, it was difficult to apply it to time-of-flight mass spectrometry.

In addition, when trying to make various ionizing means selectable, it is necessary to make the ion generation space by these ionizing means common, which limits the ionization methods that can be selected, and there is also the problem that the structure becomes complicated. It was

(Problems to be Solved by the Invention) Therefore, the present invention is a time-of-flight mass spectrometer that does not become structurally complicated, and enables ionization methods other than the laser ionization method to be applied to analyze samples. The purpose is to extend the range.

(Means for Solving the Problems) The present invention relates to a sample ionization chamber connected to a column of a liquid chromatograph via a vaporizer, and an ion introduced from the ionization chamber via an ion inlet to a time-of-flight mass. The sample is irradiated with a laser in the ionization chamber along the axial direction of the jet formed by the vaporizer and on the opposite side of the ion introduction port across the jet. Laser irradiation means, a filament that emits electrons that ionize the sample,
Discharge electrodes for ionizing the sample by the discharge ionization method are arranged in this order, and a repeller electrode is arranged in the discharge electrode section at a position facing the ion introduction port across the jet flow, and electron impact ionization method, discharge ionization method And a selection means for selecting various ionization methods of the laser ionization method so as to enable the ionization method, and arranging an ion beam deflection electrode whose applied voltage is cut in a pulsed manner between the ion introduction port and the mass analysis means. It was done.

(Operation) Therefore, various ionizing means arranged along the jet flow formed by the vaporizer generate ions in the jet flow and carry the ions generated by the jet flow to a predetermined space. It becomes free, and it is not necessary to share the ion generation space of various ionization means, and the structure of the ionization chamber can be simplified.

Further, in the time-of-flight mass spectrometer, it is necessary to accelerate ions simultaneously and in a pulsed manner, but an electron impact ionization method or a discharge ionization method other than the laser ionization method, which is difficult to be pulsed, is carried out. In this case, the voltage applied to the ion beam deflecting electrode disposed between the ion introducing port and the mass spectrometric means is cut for a very short time, and ionized in the ionization chamber to pass through between the ion beam deflecting electrodes from the ion introducing port. The ion beam incident on the mass analysis space is pulse-modulated.

(Embodiment) An embodiment of the present invention is shown in the drawings.

I is an ionization chamber, and 1 is a vaporizer for heating and evaporating the sample solution flowing out from the LC, which can be replaced with a thermospray ionization probe that also performs ionization by friction by using different vaporizers. Reference numeral 2 denotes a laser gun attached to the ionization chamber I along the axial direction of the jet flow formed by the vaporizer 1 and on the opposite side of the ion introduction port 6 with the jet flow interposed therebetween.
By concentrically irradiating the sample solution that has passed through the column and exited from the vaporizer 1, the sample solution is vaporized and ionized, or the vaporized sample is ionized. The irradiation position of the laser light is preferably near the exit of the vaporizer.

Similarly, reference numerals 4 and 5 are a filament and a discharge electrode attached to the ionization chamber I along the axial direction of the jet formed by the vaporizer 1 and on the opposite side of the ion introduction port 6 across the jet. Is applied with a negative voltage to the ionization chamber I, causing electrons to collide with the vaporized sample to be ionized. Further, the discharge electrode 5 ionizes the sample by corona discharge. R is a repeller electrode located at the position of the discharge electrode 5 facing the ion introducing port 6 with the jet flow interposed therebetween, and pushes out the ions from the ion introducing port 6 toward the mass spectrometric means. Reference numeral 7 is an iontophoresis focusing lens system for introducing ions ionized in the ionization chamber I and extruded through the ion introduction port 6 into the time-of-flight mass spectrometer M. Reference numeral 8 is an ion beam deflection electrode, which is usually applied with a voltage. The introduced ions are deflected so that the ions do not enter the mass analyzer M, and the voltage is cut for a very short time to introduce the ions into the mass analyzer M only when the analysis is performed. Reference numeral 9 is an accelerating electrode for accelerating the ions, and 10 is a detector for detecting the ions.

Next, the measurement operation will be described. When only the laser beam is used for ionization, the laser beam is irradiated in a pulsed manner in the vicinity of the exit opening of the vaporizer 1 to ionize the sample solution flowing out from the vaporizer 1. Ions ionized by the laser light are extruded from the ionization chamber I by the repeller electrode R through the ion introduction port 6, pass between the ion beam deflection electrodes 8 by the ion introduction converging lens system 7, and are accelerated by the acceleration electrode 9 to be subjected to mass spectrometry. It is incident on the space.

Assuming that the mass number is m, the charge is Z, and the applied voltage is V, the velocity v at which the ions are accelerated is Therefore, the ions having the highest V / m are detected in order by the detector 10, and the mass spectrometry is performed according to the detection time.

When the sample is ionized by using the vaporizer 1, the filament 4 and the discharge electrode 5, the ionization is continuously performed. Therefore, the voltage applied to the ion beam deflection electrode 8 is pulse-cut, and the ionized ion is pulse-modulated. Then, it is incident on the mass spectrometer M for a short time.

(Effects of the Invention) Although there are ionization methods suitable for each sample, according to the present invention, various ionization methods can be selected. Therefore, a highly sensitive time-of-flight mass spectrometric method can be used without limitation on the type of sample. It is possible to improve the measurement accuracy and sensitivity of mass spectrometry.

[Brief description of drawings]

The figure is a block diagram of an embodiment of the present invention. I ... Ionization chamber, M ... Time-of-flight mass spectrometer, R ...
... repeller electrode, 1 ... vaporizer, 2 ... laser gun,
3 ... Window, 4 ... Filament, 5 ... Discharge electrode, 6 ... Ion introducing port, 7 ... Ion introducing converging lens system, 8 ... Deflection electrode, 9 ... Accelerating electrode, 10 ... Detector

Claims (1)

[Claims] 1. A sample ionization chamber connected to a column of a liquid chromatograph via a vaporizer, and a mass spectrometry for mass-analyzing ions introduced from this ionization chamber through an ion introducing port by time-of-flight mass spectrometry. Means for irradiating the sample with laser along the axial direction of the jet formed by the vaporizer in the sample ionization chamber and on the opposite side of the ion introduction port across the jet. , A filament that emits electrons that ionize the sample, and a discharge electrode that ionizes the sample by the discharge ionization method are arranged side by side in this order, and also at the position facing the ion introduction port across the jet flow and at the discharge electrode portion. A repeller electrode is placed, and electron impact ionization method, discharge ionization method, laser An ion beam deflecting electrode whose applied voltage is cut in a pulsed manner between the ion introducing port and the mass spectrometric means. A liquid chromatograph / mass spectrometer characterized by being arranged.