JPH04105047A - Method for judging ending of isomerization - Google Patents

Abstract

PURPOSE:To sense ending of isomerization by sampling the index value exhibiting the degree of isomerization, and comparing the value, which is obtained through summarizing while weighting is applied larger to difference between two adjoining values closer to the current point of time, with the value obtained by multiplying the latest sampling value with a certain factor. CONSTITUTION:Measurement is commenced by measuring the intensity of the fluorescence having a specific wavelength by a fluorescent spectral photometer while the specimen is irradiated with ultraviolet rays having specific wavelength, and one index value is sampled at Step (a). At Step (b), the content of register is reduced stage by stage, and at Step (c) the sampling data is accommodated in the uppermost empty space, and a Step (d) the data at each stage in the register is read and the sum DELTA with weighting is applied to the difference between adjoining sampling values is calculated. At Step (e), the latest sampling data So is multiplied with an appropriate factor alpha, followed by examination whether alphaS>DELTA/SIGMAWi or not. Thus sampling of index value is performed at certain intervals, and if Yes is given at Step (e), Step (f) judges that isomerization is ended, and Step (g) performs fluorescent measurement to complete the inspection.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for detecting the end point of an isomerization reaction of substances contained within a sample.

(Prior art) As a method for detecting kerosene or heavy oil illegally mixed into light oil, a method is used to monitor the fluorescence intensity of a fluorescent substance called coumarin added to kerosene or A heavy oil. . In this case, when coumarin is irradiated with ultraviolet light, it isomerizes and exhibits stable fluorescence intensity.
The light oil sample is irradiated with ultraviolet light in advance to complete the isomerization reaction of coumarin, and fluorescence measurements are performed at a location where the fluorescence intensity is stable.

Conventionally, in order to determine the completion of isomerization of coumarin as described above,
A fluorescence spectrophotometer can be used to irradiate a sample with single-wavelength ultraviolet rays to examine the temporal change in fluorescence intensity, and a human can determine the completion of isomerization, or an appropriate time can be determined based on experience using a fluorescence spectrophotometer. It was assumed that the isomerization had ended.

However, it takes a lot of effort for a human to judge when isomerization has ended, and it wastes the time of the person conducting the analysis. Also, if you set an appropriate time and uniformly end the isomerization, it will not take much effort, but the time can be set appropriately for the case where the coumarin in the light oil is not completely thermally isomerized. If the sample is exposed to sunlight or irradiated with ultraviolet light before being tested, isomerization will have progressed to some extent, so do not set an unnecessarily long time for the isomerization to complete. As a result, inspection efficiency decreases, and if too much time is taken for isomerization, the sample deteriorates and the lightning intensity may even decrease.

(Problems to be Solved by the Invention) The present invention aims to provide a method that can automatically and correctly detect the completion of the above-mentioned isomerization regardless of the previous history of the sample.

(Means for solving the problem) Index values indicating the degree of isomerization are sampled at appropriate time intervals, and the sampling value close to the current time is calculated based on the difference between adjacent sampling values from the past to the latest sampling value. It is determined that the isomerization has ended when the value obtained by adding a larger weight to the difference between them becomes smaller than the value obtained by multiplying the latest sampling value So by a certain coefficient.

(Function) In the case of the above-mentioned conventional example, the index value indicating the degree of isomerization is the fluorescence intensity. In this case, the fluorescence intensity generally shows a change over time as shown in FIG. 3 due to ultraviolet irradiation. The purpose is to detect point a as early as possible at which the change in fluorescence intensity becomes horizontal in this figure. This is because the test cannot be performed in the stable range after point a, and the determination of the completion of isomerization is delayed.
At this point, sample deterioration occurs during inspection. In the present invention, index values are sampled at appropriate time intervals, and if the completion of isomerization is determined based on the difference between the latest sampled value and the previous value, the measured value ( Misjudgment due to variations in equipment noise). In the present invention, by referring to the past several sampling values and by referring to the absolute value of the difference between adjacent sampling values, the influence of variations in the sampling values each time is removed, and the determination becomes accurate. The simple sum of the differences between adjacent sampling values of the past several points is the amount of change in the index value between the oldest and newest of the plurality of sampling points.

In FIG. 4, S is the index value, '0.1+2. ...Let n be the sampling point, and let the index value at each sampling point be S
o, Sl, S2. ...and... The sum DO of absolute differences between sampling values of r4 is Do=lSo-311+1S1-821+...-+l
-3n, which is equivalent to 5o-Sn if the curve is a simple increase. If we plot this DO above the 0 point, we get
As the sampling progresses, the value of DO gradually decreases, and curve D shows how this changes.

Since the curve D becomes ○ when all n sampling points enter the horizontal part of the curve S, if the completion of isomerization is judged as the point where D becomes 0, the judgment will be made only for a time n times the sampling interval. You'll be late.

In the present invention, the difference between each sampling value is added with greater weight given to the difference closer to the current time, thereby bringing the sum value closer to (So-Sl) and averaging out the variations in the sampling values each time. The sum △ in the present invention is △=wl 1so-Sl l+W21s1-82 and Wl
>w2>...>w n, and the change in Δ as the sampling progresses is shown by the curve Δ in FIG.

This curve is steeper than curve D, and the point where it becomes 0 is closer to the left than in curve D. As a practical matter, it is difficult to detect when Δ becomes 0 (because it fluctuates around ◯), so it is determined that isomerization has ended when Δ becomes smaller than a certain value. This certain value is S.

It is more reasonable to set it large when So is large (rather than keeping it constant), so the completion of isomerization is determined as kSo>△.

(Example) Fig. 1 is a flowchart showing an embodiment of the method of the present invention. Fig. 2 shows a register used in this embodiment. This register is used every time an index value is sampled. The data inside the register is moved down one stage at a time, and the latest index value is stored in the top space.In this way, the register contains So, Sl, S2...Sn index value is stored.

Returning to FIG. 1, start measurement. The measurement involves irradiating the sample with ultraviolet light of a specific wavelength using a fluorescence spectrophotometer and measuring the intensity of fluorescence at a specific wavelength. Become. When the measurement operation starts, one index value is sampled (a). Next, lower the contents of the register mentioned above one step at a time (B), store the data sampled in (B) in the empty space in the container (C), then read the data in each step in the register, and Calculate the sum △ △=ΣWiSi−5i, which is a weighted difference between the sampling values. 2〉The latest sampling data S.

Multiply by an appropriate coefficient α and check whether αSo>Δ/ΣWi). If this judgment is No, the operation returns to (A), and the index value is sampled at regular time intervals in this way, and when the result of step (E) becomes YES, it is determined that the isomerization has ended (Go). , perform fluorescence measurement (g), and complete the inspection of one sample.

(Effects of the Invention) According to the present invention, since the completion of isomerization can be automatically determined, labor saving can be achieved, there is no risk of delay in determination unlike human determination, high determination accuracy is achieved, and multiple Since the sampled value of is used for judgment, the influence of index value dispersion due to accidental index value abnormalities such as when the stark for stirring the sample suddenly rotates abnormally and other miscellaneous causes is canceled and reduced. This improves the accuracy of judgment.

[Brief explanation of drawings]

Fig. 1 is a flowchart of an embodiment of the present invention, Fig. 2 is an explanatory diagram of a register used in the embodiment, Fig. 3 is a graph showing a general tendency of changes in index values, and Fig. 4 is a flowchart of an embodiment of the present invention. FIG. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] Index values indicating the degree of isomerization are sampled at appropriate time intervals, and the differences between adjacent sampling values from the past to the latest sampling values are given greater weight as the differences between sampling values closer to the current time are A method for determining the end of isomerization, characterized in that it is determined that the isomerization has ended when the added value becomes smaller than the value obtained by multiplying the latest sampling value So by a certain coefficient.