JPS61277050A - Apparatus for analyzing isotope - Google Patents

Abstract

PURPOSE:To make it possible to record the profiles of the chromatograms of a group of isotopes of the same element in a height aligned and superposed state, by introducing chromatogram effluent components into a mass analyzer and inputting all ion detection signals to a computer. CONSTITUTION:A computer 8 preliminarily reads the output of an entire ion detector 5 at a constant time interval and, when one analytical operation is finished, the computer 8 takes the peak data of the same mass from the mass spectrum data corresponding to each peak of the output of the entire ion detector 5 to arrange the same on a time axis and forms the profile data of the peak of the chromatogram of the isotope thereof and calculates a peak height or area from said profile. Then, the relative quantity of the isotopes of the same element is determined and the relative quantity of the isotopes of the max. quantity is set to 100 to calculate the presence quantity of the other isotope or a total quantity is set to 100 to calculate the respective ratio while the peak profile of the chromatogram of each isotope is drawn in a height aligned and superposed state.

Description

[Detailed description of the invention] A. Field of industrial application The present invention is useful for measuring the quantitative ratio of elemental isotopes. It decays and changes into various elements containing many isotopes. In order to measure the isotope ratio of elements in such products, conventionally the elements are separated using a chromatograph mass spectrometer, and the isotopic composition of the separated elements is measured by mass spectrometry. In this case, specify a specific mass number in the mass spectrum at the same timing, and multiply the peaks of other mass numbers by the specified relative ratio to create the profile of the temporal change of each spectrum peak. The profile and height of temporal changes were aligned and recorded overlappingly. In other words, each peak in the chromatogram corresponds to a different element, and since each element contains isotopes, mass spectrometry yields a mass spectrum with multiple peaks. By arranging the graphs in chronological order according to the outflow time, a chromatogram of each isotope of each element can be obtained. These chromatograms for the same element are recorded overlappingly, with the heights aligned. In FIG. 3, T is the time axis, the peaks on the same axis are CC', the detection output peaks of the chromatograph, and the values of each peak on the time axis are retention times. The axis perpendicular to the time axis is the mass axis, and when one peak C of the chromatographic output is detected, mass spectra are drawn on each mass axis when the chromatographic outflow components are mass analyzed at fixed time intervals. A mass spectrum represents a group of isotopes of an element. By arranging peaks of the same mass in this mass spectrum in the time axis direction, profiles m, m', etc. of the chromatogram peaks of the isotope of that mass can be obtained. Now, by multiplying the chromatograms of each mass by an appropriate coefficient to make the heights the same, and recording them overlapping each other, the chromatogram shown in Figure 2 is drawn. At this time, the widths of the chromatogram peaks of each isotope roughly match. The reason for performing such recording is as follows. The fact that the widths of each peak in the multiple peaks in Figure 2 are almost the same is proof that the atoms forming each peak are chemically the same, that is, they are isotopes of the same element. A wide or narrow peak Q indicates that the affinity for the chromatographic column packing material is different from that of the others, and it cannot be recognized as a true isotope peak, but may be due to the chromatographic peak of another substance coincidentally occurring at the same location. If the isotope peak is so small that it has a distorted waveform or a peak that is not suitable for area calculation, recording in the above manner can prevent inappropriate isotope detection. It excludes them.

However, in the conventional method described above, unless the quantitative ratio between each isotope that makes up one peak in the chromatogram is known,
The peak heights of the chromatograms for each isotope cannot be made the same. Therefore, once a mass spectrum is measured and recorded for each peak in the chromatogram using a chromatography mass spectrometer, the amount ratio between each isotope is calculated and the coefficient value to be multiplied by each spectrum peak is determined. This requires a complicated procedure of analyzing with an analyzer, multiplying the mass spectrum peak by the above coefficient, and recording the multiple chromatogram described above.

C6 Problems that the invention attempts to solve This is an attempt to eliminate the complicated procedures mentioned above.

21 Means for Solving Problems The chromatograph effluent components are introduced into the mass spectrometer, all ion detection signals are input into the computer, the computer causes the mass spectrometer to perform mass scanning at appropriate time intervals, and the mass spectrum is Capture and store data. Alternatively, the chromatogram data of a specific mass fragment peak can be captured and stored using a mass fragment graph. After the analysis operation is completed, the height or area of the chromatogram peak for the same mass number is calculated for the mass spectrum data of each peak of the total ion detection output, and the height or area of the chromatogram peak for other masses is calculated for the maximum height or area. The height or area ratio is calculated, the chromatogram of each mass number is multiplied by the above ratio, the chromatogram peak profiles with the same height of each peak are superimposed and output to the recorder, and the height of each of the above peaks is output. The total area of all chromatograms of masses forming the isotope is set as 100, and each ratio is printed out from the area or height.
Alternatively, isotope ratios were calculated in various forms by printing out the height or area of each peak when the maximum peak was taken as 100.

According to the present invention, mass spectrum data of each chromatographic peak is collected in one analysis operation, and data of each chromatogram peak of a group of isotopes of the same element is collected using the memory function and data processing function of the computer. Since the profiles are recorded in layers with the same height, it is possible to measure isotope ratios with simple operations.

Embodiment FIG. 1 shows an embodiment of the present invention. 1 is a gas chromatograph, and 2 is an interface that mediates the connection between the gas chromatograph and the mass spectrometer MS. In the mass spectrometer, 3 is an ionization chamber, 4 is an ion focusing lens, 5 is a total ion detector, 6 is an electromagnet for mass analysis, and 7 is an ion detector. 8
The computer controls the entire device. 10 is an excitation power source for the electromagnet 6, and 11 is an ion accelerating voltage source.

The computer 8 reads the output of the total ion detector 5 at regular time intervals, and this data becomes chromatogram data. The computer 8 detects the rise and fall of the peak in real time from this data, and operates the electromagnet power supply 10 of the mass spectrometer from the rise to the fall to scan the mass of the mass spectrometer at fixed time intervals. The ion detector output during that time is being read. This data is mass spectrum data at each peak in the chromatogram.

When one analysis operation is completed, the computer 8 picks up the data of the peaks of the same mass from the mass spectrum data corresponding to each peak of the total ion detector output, arranges them on the time axis, and calculates the peaks of the chromatogram for that isotope. Create profile data and calculate peak height or area from the profile. In this way, the relative amount of isotope is determined for each element, and the relative amount of the maximum amount of isotope for each element is determined by 10
The abundance of other isotopes is calculated by setting the amount to 0, or each ratio is determined by setting the total amount to 100, and the peak profiles of the chromatograms of each isotope are drawn in a superimposed manner with the same height. FIG. 2 shows the peak profile of the chromatogram of each isotope that constitutes the gradient peak of the same element drawn in this manner.

Effects The apparatus of the present invention has the above-described configuration and is very easy to operate because it can immediately obtain overlapping figures in which the heights of the chromatogram peak profiles of each isotope of the same element are aligned in a single analysis operation. This is particularly effective when analyzing elements with many isotopes, such as Xe.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention, FIG. 2 is a diagram in which chromatograms of isotopes forming one peak of the chromatogram are overlaid with the same height, and FIG. Figure 3 is a graph showing the relationship between the chromatogram and the mass spectrum.

Claims (1)

[Claims] It consists of a combination of a chromatograph and a mass spectrometer, and a computer that controls them and processes the data.The computer collects and holds the mass spectrum data of the components flowing out of the chromatogram, and calculates the same mass spectrum for each chromatogram peak. Collect mass peak data to create chromatogram peak profile data for the same isotope, calculate the isotope ratio data for each element from these data, and calculate the chromatogram of each isotope for each element. An isotope analyzer characterized by overlapping Gram peak profiles with the same height.