JPH04204353A - Absorptiometric analysis - Google Patents

Abstract

PURPOSE:To make recording with emphasis on specified functional group possible by multiplying every measurement data by absorbance spectrum data stored in advance of the functional group specified for each wave number for a measurement wave number range, and integrating the product. CONSTITUTION:Absorbance spectrum data F(nu) of the absorbance of a specified functional group is read from a RAM. The data number is assumed to be 1. The number N is the order number of the data allocated for each operation from the beginning of a spectrophotometer F and the absorbance spectrum data in a hard disk drive HDD is identified with this number. An absorbance spectrum data A(nu, N) specified by the number N is then read from the hard disk drive HDD and integration {I(t)} is calculated for F(nu)A(nu, N). The calculated result is stored in the RAM. Repeating that operation, the data of chromatogram I(t) is stored in the RAM. When the number N reaches the final value, the data process is finished. Then the data of the integrated value I(t) is read out and displayed on a CRT to visualize the chromatogram.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a method for detecting changes over time in specific functional groups in a sample that changes over time, such as when a chromatogram is obtained by absorbance analysis of a chromatographic fluid. This invention relates to a data processing method used for measurement.

(Prior art) When performing absorption analysis on gas chromatograph effluent gas using a Fourier transform infrared spectrophotometer and creating a chromatogram based on changes in specific functional groups over time, conventional techniques A method was used to record the change over time in the wavenumber integral of the absorption spectrum in a predetermined wavenumber range, where the absorption spectrum of the group exists. To write this as a mathematical formula, let the set wave number range be 1 to ν2, and let the absorption spectrum waveform in that range at time t be At(ν), then I' (t) = At(ν)dν, I'
(L) is recorded.

However, the above method has the following problem.In general, even a single organic substance has several functional groups in one molecule, and the absorption spectra of these functional groups overlap in the wave number range. There is.

Therefore, the integration of the absorption spectrum within the range of the absorption spectrum of one functional group is not necessarily proportional to the concentration of the target functional group, and the obtained chromatogram shows that in addition to components having the target functional group, other A peak of a component having a functional group also appeared, making it difficult to judge the analytical results.

(Problems to be Solved by the Invention) The present invention seeks to solve the above-mentioned problems when tracking changes over time in a sample by measuring the increase or decrease of a single functional group.

(Means for solving the problem) Data of the absorption spectrum profile F(ν) of the functional group to be measured is stored in advance, and recorded on the absorption spectrum axis in a predetermined wave number range at each measurement time. I did it like that. Here, SI' and SI2' are the lower and upper limits of the measurement wave number range.

(Effect) Equation H) above is the wave number in absorption measurement, and F(ν
) is an absorption spectrum specific to a functional group, and is an absorption spectrum of a sample in which A(ν) changes over time. If the concentration of all the functional groups to be measured is C(t), and the shape of the absorption spectrum due to other functional groups in the set integration range is B(ν), then A(ν)-C(t)F( ν) 10 B(shi)・(2), and the integrand of equation (1) is F (ν) A (!/) = C(t> F−(y) +
F (v) B (shi) (3) In the third section, A and B indicate the absorption spectra of two functional groups. In the figure, C shows the absorption spectrum of the sample containing the above-mentioned functional group, and the third diagram shows the absorption spectrum of C multiplied by the functional group spectrum of A.

The absorption spectra of the two functional groups do not completely overlap, and even if there is an overlap, it is only a part). Therefore, the second term on the right side of equation (3) is smaller than the first term, and when there is no specified functional group in the sample, the first term on the right side of equation (3) is smaller than the first term.
The term becomes 0, and the presence or absence of a component having the designated functional group on the chromatogram becomes extremely clear.

(Embodiment) FIG. 1 is a flowchart showing an embodiment of the method of the present invention, and FIG. 2 shows the configuration of an apparatus in which the operations shown in the above flowchart are executed.

In FIG. 2, GC is a gas chromatograph, and F is a Fourier transform infrared spectrophotometer, through which the outflow gas from the gas chromatograph is made to flow. The Fourier transform infrared spectrophotometer operates at a constant cycle, and the interferogram data for each operation is input to the CPU through the A/D converter valve, and the CPU reads this interferogram data. After the measurement is completed, the CPU performs the data processing operation shown in the flowchart in Figure 1 to calculate the chromatogram data and display it on the CRT. The operation of data processing performed by the CPU which outputs data to the printer P to draw a chromatogram will be explained with reference to the flowchart of FIG. The absorbance spectrum data of each functional organ is stored in advance in the RAM in FIG. 2, and in data processing, the operator first specifies one functional group using the keyboard K to start the data processing operation. Then, first, data F(v) of the absorbance spectrum of the designated functional group is read out (a). In this data, the upper and lower limit wave numbers ν2 of the integral of equation (1) are defined as the existence region of F(ν). ν1
is also determined automatically. In step (b), data number N is set to 1.
shall be. This data number is the Fourier transform spectrophotometer F.
This is the data ranking number assigned from the beginning for each movement.
The absorbance spectrum data in the HDD is identified by this number, and the absorbance spectrum data that differs only by the number is the absorbance spectrum data of the GC outflow gas at times that differ by one operating cycle of the Fourier transform spectrophotometer. Next, read out the absorbance spectrum data A(ν, N) in the order specified by N from the HDD.
) performs an integral calculation of I(t) in the equation (d). The calculation result is R
It is stored in AM (e), and it is checked whether N has reached the final value. If it has not reached the final value, 1 is added to N and the operation returns to (c). Thus chromatogram I
(t) data is stored in the RAM. When N reaches the final value, the data processing operation ends. Its'li RA
The data of I (t) in M may be read out and displayed on CR, T, or output to printer P to visualize the chromatogram.

In the above example, the absorbance spectrum data at each time until the completion of one chromatographic analysis is temporarily stored on the HDD.
Although the data is processed after being imported into the system, it is also possible to record the chromatogram in real time by performing the above-described data processing operation every time the absorbance spectrum measurement operation is repeated at a fixed period. In addition, in the above example, a chromatogram is obtained for only one functional group, but in some cases, it is possible to specify multiple functional groups and obtain a chromatogram for each of them to make the discrimination and identification of the sample even clearer. be.

(Effects of the Invention) According to the present invention, when tracking changes in a sample over time by changes in the concentration of a specific functional group, the absorbance spectrum of the specified functional group overlaps with the absorbance spectrum of other functional groups. Even in such cases, changes in specified functional groups can be emphasized and recorded, making it possible to accurately understand the state of changes in the sample.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the operation of an embodiment of the present invention, FIG. 2 is a block diagram showing the refinement of an apparatus for carrying out the embodiment, and FIG. 3 is a graph explaining the method of the present invention. . GC...Gas chromatograph, F...Fourier transform infrared spectrophotometer, HDD...Hard disk drive, P...Printer, K...Keyboard. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] The absorbance spectrum of the sample is measured at regular intervals, and the measured data for each absorbance spectrum is multiplied by the pre-stored absorbance spectrum data of the functional group specified for each wavenumber for the measured wavenumber range. An absorption analysis method characterized by integrating and sequentially recording the integration results.