JPH05164752A - Data processor for chromatograph - Google Patents

Abstract

PURPOSE:To appropriately decide the optimum peak detecting sensitivity in a short time by measuring and storing noise levels of all of mass numbers to be measured and deciding the peak detecting sensitivity of all the mass numbers to be measured from the average peak detecting sensitivity of several representative ions and stored contents. CONSTITUTION:A computer 2 measures and stores 6 in advance the average noise level of all of mass numbers to be measured in all the sections. Then the computer 2 finds the average peak detecting sensitivity by measuring the average noise level of mass numbers to be measured in the first section. The computer 2 successively finds the peak detecting sensitivity which is required for the current measurement from each mass number to be measured by correcting and converting the peak detecting sensitivity based on stored contents about noise level. As a result, the optimum peak detecting sensitivity is found for detecting the best peaking starting and ending points. Since the optimum peak detecting sensitivity is found for all the ion mass numbers by measuring the noise levels of several ions by one time only, the time required for deciding the optimum peak detecting sensitivity can be remarkably reduced and the analyzing process can be smoothly carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention is applicable to GC / MS, LC /
The present invention relates to a data processing device for a chromatograph mass spectrometer such as MS.

[0002]

2. Description of the Related Art In a data processing apparatus for GC / LC analysis, it is necessary to determine an optimum peak detection sensitivity in advance in order to properly detect a peak in a chromatogram. Here, the optimum peak detection sensitivity is a change gradient of a signal serving as a reference for detecting the optimum peak start point (see T _{1 in} FIG. 5) and the optimum peak end point (see T _{2 in} FIG. 5). Say.

Conventionally, a signal in a state where a sample is not injected is taken in at a constant time interval, the absolute values of the inclination angles of the signals adjacent to each other are averaged by a fixed number, and an average noise level is obtained. The optimum peak detection sensitivity was determined by multiplying by a constant coefficient. Note that FIG. 4 illustrates the data acquisition timing when the noise level is acquired with a sampling interval of 0.2 seconds. Usually, 100 pieces of data are averaged to obtain the optimum peak detection sensitivity, so that it takes 20 seconds just to capture the data.

In the mass spectrometer, the noise level of the signal greatly differs for each mass number (m / Z). Therefore, in order to detect multi-components, it is necessary to perform the above processing for each total mass number. There is.

[0005]

[Problems to be Solved by the Invention] Selective ion measurement (SI
In the case of M), usually only about 10 ions are measured at the same time (since the S / N ratio becomes worse as the number of ions increases), the mass number to be measured is switched for each peak. Figure 6
The figure shows that the mass number to be measured is switched for each peak, and that the mass number to be measured changes from the first section to the sixth section of the total ion chromatogram (TIC) one after another. Is shown.

As described above, in the selective ion measurement (SIM), the number of masses to be measured is switched for each peak. Therefore, in order to measure the noise level under the same conditions, for example, several tens of peaks are required to have a length of several hundred seconds or more. There is a problem that it takes time. The present invention has been made in view of this problem, and provides a data processing device for a chromatograph capable of appropriately determining the optimum peak detection sensitivity for all mass numbers to be measured in a short time. The purpose is to do.

[0007]

In order to achieve the above object, a data processing device for a chromatograph according to the present invention measures a noise level for all mass numbers to be measured, and predetermines the noise level or the noise level ratio. A noise level storage means to be stored, a detection sensitivity measurement means for obtaining an average peak detection sensitivity by a total ion chromatogram signal of several representative ions prior to the analysis processing, the peak detection sensitivity and the noise It is provided with a detection sensitivity determination means for determining the peak detection sensitivity for all masses to be measured in all measurement intervals necessary for this analysis based on the stored contents of the level storage means.

[0008]

The noise level storage means measures the noise level for all the mass numbers to be measured, and stores this noise level or noise level ratio in advance. Normally, the noise level ratio for each m / Z is almost constant unless the analysis conditions are changed, so that the noise level ratio is calculated for all m / Z in advance.

The detection sensitivity measuring means obtains an average peak detection sensitivity from the total ion chromatogram signals of several typical ions prior to the analysis process. Specifically, for example, using the total ion chromatogram for the mass number to be measured in the first section, the peak detection sensitivity S is calculated based on the average value of the noise level deviation.
_Ask for _T.

The detection sensitivity determining means, based on the peak detection sensitivity and the stored contents of the noise level storage means,
The peak detection sensitivities for all masses to be measured in all measurement intervals required for this analysis are determined. Specifically, for example, the ratio S _T of the sum of the noise level (or ratio) N _1j for the mass number to be measured in the first section and the peak detection sensitivity is set to the total required in this analysis. Multiply the noise level (or ratio) N (m / Z) of all masses to be measured in the measurement section to obtain the peak detection sensitivity S for each m / Z.
Determine (m / Z). The formula is as follows.

S (m / Z) = N (m / Z) / (N ₁₁ + N ₁₂ + ... + N _1n ) × S _T

[0012]

The present invention will be described in more detail based on the following examples. FIG. 1 shows a GC according to an embodiment of the present invention.
2 is a block diagram of a data processing device for / MS. This device is a gas chromatograph mass spectrometer (G
C / MS) 1 and this gas chromatograph mass spectrometer 1
A computer 2 that performs analysis processing of an unknown sample based on the above data, and an interface (I / F) 3 that connects the gas chromatograph mass spectrometer 1 and the computer 2
And a display 4 for displaying a chromatogram and the like, and a storage device 6.

FIG. 2 is a flow chart for explaining the operation procedure of the apparatus of FIG. The operation procedure will be described below with reference to the flowchart of FIG. The computer 2 previously measures the average noise level N (m / Z) for all the mass numbers to be measured in all the sections and stores it in the storage device 6 (step ST (hereinafter abbreviated as ST) 1). Here, the average noise level means an average value of deviations of the noise level I (i), and is obtained by calculating [Equation 1] for all mass numbers. In addition, in [Equation 1], I (i) is the noise level at the i-th sampling point, and T is the measurement time of the entire section.

[0014]

[Equation 1]

FIG. 3 shows the storage device 6 thus obtained.
Of the above, that is, the average noise level N (m / Z) for each mass number (m / Z). If an analysis process is to be performed, first the first
The average noise level is measured with respect to the mass number to be measured in the section to obtain the average peak detection sensitivity (ST2). For example, if the measurement target ion mass number in the first section is 5, then from the total ion chromatogram data I ′ (i) for the corresponding 5 ion mass numbers,
The average peak detection sensitivity S _T is calculated using [Equation 2].

[0016]

[Equation 2]

Note that T _1m is a measurement time of 100 pieces of data in the first section. Further, F ₁ is a coefficient that determines the ratio between the average noise level and the peak detection sensitivity, and the optimum value is obtained in advance by actual measurement. Then, the peak detection sensitivity S _T obtained in the process of ST2 is corrected and converted to obtain the peak detection sensitivity for each measurement target mass number required in this measurement (ST3). Specifically, the noise level sum (= N) for the five mass numbers stored in the storage device 6 is stored.
₁₁ + ... + N ₁₅ ) and the peak detection sensitivity S _{T in} the first section obtained in the process of ST2, the peak detection sensitivity S (m / Z).

[0018]

[Equation 3]

By the above-mentioned processes of ST2 to ST3, the optimum peak detection sensitivity for detecting the best points of the peak start point and the peak end point is obtained for the mass number to be measured in all sections of this measurement. In other words, if there is a sharp change from the optimum peak detection sensitivity, that point is the peak start point, and after a suitable amount of time, if the change is more gradual than the negative optimum peak detection sensitivity, that point is the peak end point. is there. Then, when the series of analysis processing is completed, the process returns to ST2 to perform the next analysis (S
T5).

[0020]

As described above, in the chromatographic processing apparatus according to the present invention, the noise level (or noise level ratio) for all mass numbers to be measured is stored in advance, and the actual analysis processing is performed. In addition, the noise level of several ions is measured only once, and the optimum peak detection sensitivity of the total ion mass number is obtained based on the result.

Therefore, the determination of the optimum peak detection sensitivity can be greatly shortened to facilitate the analysis process.

[Brief description of drawings]

FIG. 1 is a block diagram of a data processing device for GC / MS which is an embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of the device of FIG.

FIG. 3 shows the contents of a file storing the noise level of each ion (m / Z).

FIG. 4 illustrates a noise level sampled at regular time intervals.

FIG. 5 illustrates a peak start point and a peak end point.

FIG. 6 shows the measurement of each peak in the selected ion measurement m /
It is drawing which showed typically that Z switched.

[Explanation of symbols]

 ST1 noise level storage means ST2 detection sensitivity measurement means ST3 detection sensitivity determination means

Claims (1)

[Claims] 1. A noise level storage means for measuring a noise level for all mass numbers to be measured and storing a noise level or a noise level ratio in advance, and a total of a representative number of ions prior to analysis processing. A detection sensitivity measuring means for obtaining an average peak detection sensitivity by an ion chromatogram signal, and based on the peak detection sensitivity and the stored contents of the noise level storage means, all measurement targets of all measurement sections required for this analysis A data processing device for a chromatograph, comprising: a detection sensitivity determining means for determining a peak detection sensitivity for a mass number.