JPH0658342B2 - Recording method of measured spectrum of double-focusing mass spectrometer - Google Patents

Description

Detailed Description of the Invention a. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording a measurement spectrum in a double focusing mass spectrometer.

Normally, in a double-focusing mass spectrometer in which an ion source, an electric field, a magnetic field, and a detector (forward arrangement) or an ion source, a magnetic field, an electric field, and a detector (reverse arrangement) are arranged in this order, the electric field is accelerated by the ions. Fixed to a constant value according to the voltage and scanning the magnetic field,
That is, besides the measurement of the mass spectrum of the ionized sample molecule ions using the magnetic field as a scale, the cleavage reaction of the ions can be investigated.

Of the ions generated by the ionization of the sample molecules, the ions are metastable and decay naturally, or are activated by collision with an appropriate molecule introduced from the outside, and are further cleaved into neutral molecules and ions. In the ion cleavage reaction, the original ion before the cleavage is called the parent ion, and the ion generated by the cleavage is called the daughter ion. The mass spectra of all parent ions that give rise to daughter ions give important information for the analysis of the sample along with the mass spectra of sample molecular ions measured by scanning the magnetic field with the electric field fixed at a constant value according to the ion acceleration voltage. .

The present invention relates to the above-mentioned method for recording both mass spectra.

B. 2. Description of the Related Art When an ion (parent ion) accelerated to a predetermined energy by an ion accelerating voltage from an ion source is decomposed (split) into several daughter ions before entering an electric field, all the daughter ions having a specific mass m are produced. The parent ion mass spectrum can be measured by a so-called linked scanning method in which the electric field and the magnetic field are scanned using a double-focusing mass spectrometer while keeping the ratio of the electric field to the square of the magnetic field constant.

In the double focusing mass spectrometer, the ion acceleration voltage is Va
c and the magnetic field is B, the mass M of an ordinary ion passing through the magnetic field is C In ordinary mass spectrometry, the electric field Eo is used as the kinetic energy eVa.
It is set so that ions having c (e is the charge of the electron) pass through. Since the parent ion and the daughter ion have the same velocity in the ion cleavage reaction, if the mass of the parent ion is M, the daughter ion mass is m, and the velocity at the ion acceleration voltage Vac is v, the kinetic energy of the parent ion is Ko is The kinetic energy K of the daughter ion is Therefore Consider the case of measuring the mass spectrum of a parent ion which produces a daughter ion of mass m. The kinetic energy when a daughter ion of mass m is incident on the magnetic field is given by the above equation (2), and the acceleration voltage of the ion of mass m is (m / M) V
Since it is equivalent to becoming ac, in order for this ion to pass through the magnetic field, the magnetic field B ′ is And in order for these ions to pass through the electric field, the electric field E is to the energy (m / M) eVac Equation (3) is transformed In equations (4) and (5), Vac, Eo, and C are constants, and if m is set to a certain value, Therefore, by scanning E and B while keeping the ratio of E to B ′ ² constant, the parent ion M that produces daughter ions of mass m can be scanned.

By the way, conventionally, the mass spectrum of the parent ion obtained by the above-mentioned linked scanning method was recorded and displayed by itself, so in order to obtain comprehensive information about the sample, it was recorded separately. It was inconvenient because it was necessary to compare it with the usual mass spectrum.

C. Problems to be Solved by the Invention An object of the present invention is to solve the inconvenience in practical use of the above-mentioned conventional display method of the measurement result in the double-convergence mass spectrometer.

D. Means for Solving Problems The mass spectrum of the parent ion was recorded side by side with the normal mass spectrum recording.

E. Embodiment FIG. Shows an embodiment of the present invention. In this figure, the scale on the horizontal axis indicates mass, and the vertical axis indicates the detected intensity of ions. The spectral record extending upward on the lower horizontal axis line represents the normal mass spectrum, and the spectral record extending downward from the upper horizontal axis line is the mass spectrum of the parent ion. The above
According to the equations (4) and (5), when scanning B and E while maintaining the relation of B ′ ² / E = constant and performing link scanning,
E = Eo, In FIG. 1, the parent ion of mass m is detected and all the other parent ions have masses larger than m. Therefore, the peak of the minimum mass in the mass spectrum of the parent ion represents the daughter ion of the specified mass. This is the daughter Aeon. If the positions of the mass scales are made to coincide in the recording of both spectra, the peaks of both spectra will be difficult to understand because they overlap, so in this example, the mass scale of the daughter ion spectrum recording is slightly shifted to the left to show the peaks of both spectra. So that they do not overlap.

The present invention is not limited to the graph display as described above,
It goes without saying that the numbers may be displayed on a table.

F. Effect According to the present invention, since two kinds of mass spectra for one sample are displayed side by side, the records of the two kinds of mass spectra can be organized easily, and the understanding of the spectrum structure is greatly facilitated.

[Brief description of drawings]

The figure shows an example of measurement result recording according to the present invention.

Claims (1)

[Claims] 1. An ion source, an electric field or a magnetic field, a magnetic field or an electric field,
In a double-focusing mass spectrometer that arranges these in the order of detectors, the electric field and the magnetic field are scanned while keeping the ratio of the electric field to the square of the magnetic field constant, and from the ion source to the predetermined energy by the ion acceleration voltage. Before the accelerated ions enter the electric field, the spectra of all parent ions that are decomposed and produced by the cleavage reaction to generate daughter ions of a specific mass are measured, and the electric field is set to a constant value according to the ion acceleration voltage for the same sample. A method for recording a measurement spectrum of a double-convergence mass spectrometer, which comprises fixing and scanning a magnetic field to measure a mass spectrum, and recording both of these spectra side by side with the same mass scale.