JP2000131305A - Apparatus and method for data processing of chromatograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an apparatus and a method, in which whether or not a parameter obtained by a fitting operation is proper can be ascertained by a method, wherein a plurality of parameters found by fitting a chromatogram are compared so as to evaluate their difference and a result in which a fitting operation is proper is output, when they are approximate. SOLUTION: An analog data signal, which is sent from a chromatograph, is converted into a digital signal via an analog-to-digital converter 1 so as to be input to a central processor 5 via a peripheral-apparatus connection device 7. After that, from the command of a control-instruction storage device 2, a control command device 6 converts the digital signal into data in a specific matrix form, and the data is stored in a signal data storage device 3. By using the data which has been once stored, two chromatograms are accessed. The initial value of a function which simulates every peak from a difference chromatogram is obtained by an overlap-peak decomposition device 9 to be stored in a parameter storage device 4. An overlap-peak fitting operation is performed by a nonlinear method-of-least-squares fitting device 10, and a calculated result is output via an output device 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chromatographic data processing apparatus and data processing method.

[0002]

2. Description of the Related Art When components of a sample are measured using a chromatograph, a plurality of components may overlap a peak portion of chromatogram data, and it may be difficult to measure each component. An example of a solution to this problem is disclosed in
There is one described in JP-A-63-151851.

[0003] In the description of this publication, the overlapping peak in the chromatogram is Gaussian (EMG: Exponentially Modified).
The data curve is decomposed into individual components by fitting the data curve using a fied Gaussian) function or a Gaussian function modified by an exponential function. However, with the above-mentioned conventional method, it was not possible to confirm whether the parameters obtained by the fitting were appropriate.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a chromatographic data processing apparatus and a data processing method capable of confirming whether parameters obtained by fitting are appropriate.

[0005]

According to the present invention, in order to solve the above-mentioned problems, a chromatogram measured by injection of a known standard sample is fitted to obtain parameters. In addition, a chromatogram measured by injection of an unknown sample is fitted to obtain parameters. Then, the latter parameter is compared with the former parameter, the difference is evaluated, and in the case of approximation, a result in which fitting is appropriate is output.

[0006] The known standard sample is free from contaminants, impurities and interfering substances, and has high reliability in fitting parameters. For this reason, when the parameters obtained by fitting from the chromatogram of the unknown sample are close to the parameters of the standard sample, it can be estimated that the fitting process has been performed correctly, and the parameters are found to be valid. Conversely, when the parameters obtained by fitting from the chromatogram of the unknown sample do not approximate the parameters of the standard sample, it can be estimated that the fitting process was not performed correctly, and it can be seen that the parameters are not appropriate.

[0007]

Embodiments of the present invention will be described below.

FIG. 1 is a block diagram of a chromatographic data processing apparatus. An analog data signal sent from a not-shown chromatograph is converted into a digital signal via an analog / digital converter 1 and enters a central processing unit 5 via a peripheral device connector 7. After that, the control command unit 6 converts the data into data of a predetermined matrix format according to a command from the control command storage 2, and stores the data in the signal data storage 3.
Two chromatograms are called from the data once stored, and the overlapping peak decomposer 9 obtains the initial value of a function for simulating each peak from the difference chromatogram and stores it in the parameter storage 4. The fitting of the overlapping peaks is performed by the nonlinear least squares fitting device 10, and the calculation result is output via the output device 8.

FIG. 2 is a chromatogram of the component Arg (arginine), which is a standard sample, and FIG. 3 is the same component Arg in an unknown sample.
5 is a chromatogram when is measured.

In FIG. 2, first, a component Arg (arginine) in a chromatogram of a standard sample is fitted by a least square method of a Gaussian function by a method described in JP-A-63-151851. By fitting, four parameters (A ₀ : area, t _R0 :
Retention time, σ ₀ : standard deviation, τ ₀ : time constant) are determined. Since the standard sample Arg (0) is an isolated peak, four parameters (A ₀ : area, t _R0 : retention time, σ ₀ : standard deviation, τ ₀ : time constant) can be determined with high accuracy.

Here, the time constant is an index indicating the degree of asymmetry from the normal distribution, and is defined in the EMG function. The EMG function is represented, for example, by the third equation of US Pat. No. 5,644,503. The larger the time constant is, the more asymmetric the standard deviation is, the normal distribution is when the time constant is zero.

Next, as shown in FIG. 3, the component Arg (arginine) in the chromatogram of the unknown sample is fitted by the least square method of the Gaussian function. Contaminant peaks overlap component Arg (1) in the unknown sample, which hinders quantification. Fit Arg (1) and impurity peak IMPURITY (2) to decompose into two components. In FIG. 3, component A
Only rg (1) and impurity peak IMPURITY (2) are shown.
Normally, there are a plurality of contaminant peaks, which are represented by i. For this component IMPURITY (i), (A _i , t _Ri ,
σ _i , τ _i ) are determined.

To evaluate the validity of the fitting parameters, a holding time t _R , a standard deviation σ, and a time constant τ are used among the four parameters. The area A is quantitative information proportional to the component concentration, and is not used in this evaluation.

First, the difference between the Arg retention times t _R0 and t _R1 of the standard sample and the unknown sample in FIG.
Determine if it is within _R. Similarly, the standard deviation σ
Whether the difference between ₀ and σ ₁ is within the tolerance Σ, the time constant τ
Difference ₀ between tau ₁ determines whether within tolerance T.
If both of these determinations are passed, the process can proceed to the next step of qualitative analysis and quantitative analysis. If any of the above judgments indicate a failure, a fitting error is displayed.

In this embodiment, the evaluation based on the difference between the data of the standard sample and the data of the unknown sample is described as an example, but the judgment is made based on the ratio σ ₁ / σ ₀ or the relative difference | σ ₁ −σ ₀ | / σ ₀ . May be.

FIG. 4 shows a processing procedure in the chromatographic data processing apparatus.

In block 41, a time section for fitting a standard sample is designated using a cursor on the screen. In block 42, a fitting execution button is clicked, and in block 43, parameters A ₀ , t _R0 ,
σ ₀ and τ ₀ are output. Here, the output may be displayed on a screen or printed.

Similarly, for an unknown sample, block 4
In 4, a time interval for fitting is specified using a cursor, and in block 45, a fitting execution button is clicked. In block 46, parameters A ₁ ,
t _R1 , σ ₁ , τ ₁ are output.

Next, at block 47, the fitting of the determination allowable width T _R, sigma, and inputs the T. Then, at block 48, the validity of the fitting is evaluated, and at block 49, the determination result is displayed.

FIG. 5 shows an operation procedure when fitting is performed by a data processing device simultaneously with measurement using a chromatograph.

In block 51, a time section for fitting is designated for the standard sample and the unknown sample.
In block 52, the determination allowable width T _R, sigma, and inputs the T. In block 53, the measurement of the standard sample and the unknown sample is performed, and in block 54, fitting is performed.

Finally, the result is output at block 55. The result may be displayed on a screen, printed by a printer, or output to external data. The results are output as parameters A ₀ , t _R0 , σ ₀ , τ ₀ , A ₁ , t _R1 , σ ₁ , τ ₁ , fitting determination results, peak identification, and quantitative analysis results.

Although the present embodiment has a single main peak of the standard sample, it can be applied to the case of overlapping peaks.

As described above, it is possible to confirm whether the parameters obtained by the fitting are appropriate, and to improve the accuracy and reliability of the analysis result.

[0025]

As described above, according to the present invention, it is possible to confirm whether parameters obtained by fitting are appropriate.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a chromatographic data processing device.

FIG. 2 is a chromatogram for a standard sample.

FIG. 3 is a chromatogram for an unknown sample.

FIG. 4 shows a processing procedure in a chromatographic data processing device.

FIG. 5 is an operation procedure when fitting is performed by a data processing device simultaneously with measurement using a chromatograph.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Analog-digital converter, 2 ... Control command storage, 3 ... Signal data storage, 4 ... Parameter storage, 5
... Central processor, 6 ... Control commander, 7 ... Peripheral device connector,
8 output device, 9 overlapping peak decomposer, 10 non-linear least squares fitting device.

Continued on the front page (72) Inventor Kisaburo Deguchi 832 Nagakubo, Horiguchi, Hitachinaka City, Ibaraki Prefecture Within Hitachi Measurement Engineering Co., Ltd. (72) Inventor Masato Fukuda 832 Nagakubo Horiguchi, Hitachinaka City, Ibaraki Prefecture 2 Hitachi Measurement Engineering Co., Ltd. F-term (reference) 2G045 DA35 FB06 FB07 HA09 JA01 JA04 JA05

Claims (2)

[Claims] 1. A chromatographic data processing apparatus for measuring a component of a sample by a chromatogram, wherein fitting is performed using a Gaussian function or a Gaussian function modified with an exponential function for overlapping peaks of data obtained from the sample. A fitting device that compares the nonlinear parameter estimated and estimated with the nonlinear parameter similarly obtained from the standard sample; and an output device that outputs a result in which the fitting is appropriate when both parameters are approximated. A data processing apparatus comprising: an overlapping peak decomposer configured to decompose overlapping peaks of the data into individual components using a non-linear parameter obtained from a sample. 2. A chromatographic data processing method for measuring a component of a sample by a chromatogram, wherein a fitting is performed using a Gaussian function or a Gaussian function modified by an exponential function with respect to overlapping peaks of data obtained from the sample. The non-linear parameters estimated and compared with the non-linear parameters obtained in the same manner from the standard sample are output, and when both parameters are approximate, it is output that the fitting is appropriate. A data processing method characterized in that overlapping peaks of the data are decomposed into individual components using non-linear parameters.