JP3055147B2 - Chromatographic mass spectrometer data processor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data processing device for a chromatograph mass spectrometer.

(Prior Art) In a conventional chromatograph mass spectrometer, a chromatogram is drawn based on all ion detection signals of the mass spectrometer, and a mass spectrum of each peak of the chromatogram is recorded. The substance that formed the peak of the chromatogram is usually a single substance, but may be a mixture of a plurality of substances that are insufficiently separated. In the chromatogram drawn by all ions as described above, it is unknown whether each individual peak is a single substance peak or a mixture peak. In such a case, when several peaks of mass are selected from the mass spectrum and the temporal change of the ions of the mass, that is, the chromatogram is plotted, the separation state of each peak of the chromatogram can be determined. Is often used for analyzing the results of analysis by a chromatograph mass spectrometer.

(Problem to be Solved by the Invention) According to a method of selecting an ion having an appropriate mass from data of a mass spectrum obtained by a chromatograph mass spectrometer and drawing a chromatogram for the ion, an individual ion chromatogram of the total ion chromatogram is obtained. Unless an ion representative of the component representing the peak is selected, it is difficult to analyze the analysis result by the chromatograph mass spectrometer. However, since the mass spectrum corresponding to each peak in the chromatogram is complicated, when there are many peaks in the total ion chromatogram, the task of specifying an ion having an appropriate mass from the mass spectrum for each peak is This is a complicated task that requires a great deal of labor. Accordingly, the present invention provides a data processing apparatus capable of automatically designating an appropriate ion for each individual peak of the total ion chromatogram and automatically forming a chromatogram for each ion.

(Means for Solving the Problems) A library of mass spectra of various substances is prepared, and the mass spectrum of each peak of the total ion chromatogram is compared with the mass spectrum in the above library to have the most similar mass spectrum. A substance is retrieved, a mass corresponding to a molecular ion of the substance is designated, and a chromatogram for each ion of each designated mass is displayed.

(Action) In the chromatograph mass spectrometer, data of the total ion chromatogram and data of the mass spectrum for each peak of the total ion chromatogram are obtained.
Since mass spectrum data is obtained by sampling mass spectrum data at fixed time intervals for each peak of the chromatogram, if one ion is designated from the mass spectrum and its detection intensity is plotted in time series, one peak A chromatogram for is drawn. That is, in the present invention, a chromatogram for each ion having a designated mass is drawn using the total ion chromatogram obtained by the chromatogram mass spectrometer and the mass spectrum data for each peak of the chromatogram. Here, in order to designate one mass ion for each peak of the chromatogram, prepare a library containing mass spectra of various substances in advance,
The mass spectrum obtained for each individual peak of the chromatogram is compared with the mass spectrum of each substance in this library, and the best match is found. By this operation, the identification of each peak component of the chromatogram is performed. In general, the mass spectrum of a sample substance depends on the ionization method when ionizing sample molecules,
Since many molecules are fragmented to generate many fragment ions, many peaks appear. However, since the appearance of the fragment ions differs depending on the substance, the sample can be identified by the pattern of the mass spectrum. On the other hand, fragment ions of various substances (organic substances) are composed of atoms or atomic groups such as H and CH _2, and therefore, in many substances, individual peaks of a mass spectrum often overlap each other. Therefore, even if an arbitrary mass spectrum peak is designated for each substance, if the peak is not a fragment ion unique to the substance, there is no advantage in drawing a chromatogram for the ion. When a sample molecule is ionized, the sample molecule is fragmented into many fragments, large and small, depending on the ionization method, but it is lighter to ions or sample molecules that are hardly fragmented at the position where one H atom is removed. Ions are also formed as ions are bound, and such ions have approximately the same mass as the molecular weight of the sample material. In other words, the parent ion of the sample substance is an ion having a unique mass of the sample substance.
In the present invention, individual peaks of all ion chromatograms are identified using the library, and based on the identification results, the mass of the parent ion is designated from the mass spectrum data of the individual peaks. This is for drawing a chromatogram. Since many such chromatograms are drawn for each ion of each mass, several lines are drawn, but if they are drawn with the time axis aligned, one of the total ion chromatograms will correspond to each peak of the total ion chromatogram. If two peaks are completely separated and a single substance, one peak is recorded in one chromatogram of each mass ion at the same time position as the above-mentioned one peak of the total ion chromatogram. If the peak of the chromatogram is a peak of incomplete separation, chromatogram peaks are drawn at two to several times at the same time in the chromatogram of each mass ion, and the peak is incompletely separated. It turns out that.

(Embodiment) FIG. 1 shows an apparatus according to an embodiment of the present invention. In this figure, reference numeral 1 denotes a chromatograph mass spectrometer. The output of the ion detector is taken into a CPU for performing data processing via an interface 2 and stored in an internal memory 3. Reference numeral 4 denotes a library in which mass spectrum data of various kinds of substances is stored in an external memory.

FIG. 2 is a flowchart of the operation of the CPU in the above-described device. The CPU first detects peaks from the data of all ion chromatograms taken into the memory 3 (A), and sequentially reads out mass spectrum data corresponding to the time from the memory 3 according to the time at the center of each peak (B), The substance having the highest degree of coincidence is found by comparing the mass spectrum data of various substances in the library stored in the memory 4 (c), and the substance name and the mass of the parent ion of the substance are stored in the memory 3 (d). ) This operation is performed for all peaks of all ion chromatograms. When this operation is completed for all peaks, the ion of the chromatograph mass spectrometer of the memory 3 is stored for each parent ion mass stored in the memory 3 in the step (d). The intensity data of the spectrum peak of the mass of the parent ion is read out from the detection output data, output to a printer (FIG. 1) and recorded in chronological order, and a chromatogram for each parent ion is drawn (e). ).
In step (e), a total ion chromatogram is also drawn, and the mass, mass,
Print the substance name.

FIG. 3 is a chromatogram drawn in the above step (e), and the numbers are the masses of parent ions. An example of the matching method in the step (c) is as follows. The library lists various substances in order of molecular weight. The largest mass peak (which is not necessarily the strongest) is found from the actual mass spectrum, thereby limiting the molecular weight search range in the library, and then the largest mass peak in the measured mass spectrum. From the strongest peak in order, compare the mass spectrum of each substance in the library with the corresponding peak intensities, and calculate the coincidence rate of the intensities of the corresponding peaks. Find the largest ratio with the selected peak number. The mass spectrum on the library side of the substance found in this way is subtracted from the measured spectrum, and if there is any remaining, the same search operation as above is repeated for the remaining.

In FIG. 3, the first peak p1 of the total ion chromatogram
Chromatogram peaks of the respective ions having masses of 68 and 74 are present corresponding to the above, and it can be seen that the peak of p1 is an overlapped peak of two substances. Further, the peaks p2 and p3 of the total ion chromatogram both show peaks on the chromatogram of ions having a mass of 202, which indicates that the molecular weight of the substance of each peak was coincidentally the same.

(Effects of the Invention) According to the present invention, chromatograms for ions of various masses are automatically obtained from data obtained by a chromatograph mass spectrometer, and the ions of various masses are obtained by analyzing the total ion chromatogram. Since the ions are representative of each peak, complete separation by chromatography is achieved.
Not only the identification of imperfect peaks but also the comparison of chromatograms between samples makes it clear that the differences are better than the pattern comparison of a mere total ion chromatogram, which facilitates analysis of the analysis results.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of the apparatus of the present invention, FIG. 2 is a flowchart of the operation of the apparatus, and FIG. 3 is a chromatogram drawn by the apparatus. 1. Chromatographic mass spectrometer, 2. Interface, 3. Internal memory, 4. External memory, 5. Printer.

Claims (1)

(57) [Claims] A library memory storing mass spectrum data of various substances; a memory storing chromatogram data and mass spectrum data of each peak of the chromatogram over time; and detecting peaks from the chromatogram data. For each peak, the mass spectrum data corresponding to the peak is taken out from the memory, compared with the mass spectrum data in the library memory, the substance having the best match is found, and the parent ion mass of the found substance is found. A data processing unit for a chromatograph mass spectrometer, comprising: data processing means for designating and reading the peak intensity of the ions of the designated mass from the mass spectrum data in the memory and recording the peak intensity of each designated mass ion in time series. .