JPS5970955A - Control of titration - Google Patents

Abstract

PURPOSE:To enable high speed titration, by controlling the dripping speed of a dripping liquid so as to adjust a minute potential change amount to a minute dripping time to a predetermined value. CONSTITUTION:A control apparatus 8 performs the feed-back operation of the change in a titration system detected by a detection electrode 3 and a comparison electrode 4 and outputs a signal corresponding a speed having to drip a titration liquid to a burette driver 10 to perform titration control and final point control. The feed-back operation is performed in such a manner that a minute potential change amount to a minute dripping time in an entire titration process is coincided with a predetermined value and titration is finished when the electric amount detected by the detection electrode 3 and the comparison electrode 4 reaches a titration final point. By this constitution, the dripping speed of the titration liquid can be sufficiently increased directly after the titration is started and high speed titration is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic titration method that reliably prevents failure in end point control and enables high-speed titration.

The complexity of determining the amount imt and the interval between drops when titrant is dropped little by little into the test liquid and titration is performed based on the potential change obtained with the electrode inserted into the test liquid. An automatic titration device that eliminates this has been put into practical use.

This self! 1iIJπ~ There are several methods for determining the
As a method to prevent this (due to the rise in temperature, the titrant is dripped until it has passed the specified end point),
Read the ratio of the potential change ΔE to the minute drop amount Δml, determine the next drop amount and the drop speed, and then check again. A method of repeating the previous work of rising and falling (for example, Tokko Shoj2-Zi
lly issue). However, this conventional method only controls the amount of minute drops and the amount of potential change, but does not control the reaction time. Therefore, if the reaction between the test solution and the titrant solution is slow, sufficient 1tjlJ control cannot be achieved, and in order to reliably prevent failure in endpoint control, the reaction time must be longer than the required reaction time. Since it is necessary to perform control while maintaining the same working time, there is a drawback that titration requires a lot of time.

In addition, as an attempt to improve the above-mentioned drawbacks, the determination of the next dropping condition in the above-mentioned conventional method was changed to a much smaller minute dropping amount Δm.
/ and a method using a potential ΔE has also been used, but it is not essentially a solution to the slow reaction mentioned above,
It has the same drawbacks as above.

Therefore, in view of the above-mentioned drawbacks, Kibori J is an improved version of this, and in the i14 system, the F ratio for the titration amount ml is
[As shown in Figure 1, the titration curve showing the change in iEtateE has a small slope in the region after the start of establishment, and the titration end point (ffil
We have provided a feedback method that allows automatic titration to be performed at high speed and without failure at the end point. It is.

That is, the present invention continuously drops one standard solution into the test liquid,
The change in the titration system is detected electrically, and the minute change in position (x) with respect to the minute dripping time is
-/7tn matches the predetermined value. Note that the titration end point may be other than the inflection point.

In other words, in the titration system, in order to control the end point to 711, the rlj of the 7H constant solution should be adjusted near the titration end point.
111 (lower) of both foot fluids should be performed at a very small speed such that the lowering speed does not exceed the reaction speed of the test solution and titrant solution, and the dropping speed near the beginning of the established UFJ is not a problem.

Therefore, after starting the formulation and after 71c+, make the subordinate speed of the titrant sufficiently large. Near the official end point 1/J, the drop speed should not be faster than the total reaction speed) If the end point control fails, it will be a good high. The enactment is a bow.
Becomes JE. Then, if the above glue +1 is 2 in the total f1.8 constant state, and the minute potential change i with respect to the minute f potting time is fixed at one point, is there a preferable direction? -1, 111 constant of the test liquid was applied to the reaction bed (i) at a rate of 14 kg overnight.
The European titration method will be described later. ) is the small drop rate XO''/it for the micro-dropping time of a>i constant end point (inflection point of 8 degrees) at 1,8 degrees.

Hereinafter, if the present invention is implemented one time, then the following steps will be taken.

Figure 1 is an illustration of the automatic titration device used in the Kidori J method.
11) is a container such as a beaker filled with the test liquid (2), (3) is a detection electrode (e.g. PH electrode, ion electrode, platinum' electrode), +41 is a reference electrode, (5)
j is a dripping nozzle for the formulation solution, (6) is a detection voltage, a power supply that increases the potential difference between the hawk (3) and the reference electrode (4) by +1, and converts the analog output of the f7Ht buffer amplifier (6) into digital. /D converter, (8) is a control device (comprised of J'LJ,
+9) is a titration piston burette that sends the titrant liquid to the established nozzle (5) by the movement of the piston (9a), and 00) is the control number output from the control device (8). A burette driver (Ill is inserted into the container Ill) that rotates a built-in pulse motor (not shown in the figure) at a speed according to A rotor made of ferromagnetic material that stirs the test liquid (2) is installed at the bottom of the container fil, and the magnetic force is used to stir the sample liquid (2).
This is a stirring device that remotely rotates a rotor (11) through the + bottom plate.

In the component device d (1″4), the control device (8)
Changes in the titration system detected by the detection electrode (11) and comparison electrode are feedback-calculated, and a signal corresponding to the speed at which the formulation liquid should be dropped is sent to the buret driver 110.
) to perform titration control and end point control.

The above feedback calculation is performed to a predetermined value,
The titration is carried out in such a manner that the minute potential y change amount x-jEm7Δ with respect to the minute drop time in the entire titration process is the same. Then, when the amount of electricity detected by the detection electrode, the first electrode, and the comparison electrode (12) reaches the titration end point (titration inflection point), the titration is terminated.

Next, 11 for calculating the most preferable value of the above predetermined values.
An example of the Reishi method will be explained.

This ol determination method performs feedback control so that the dropping speed of an unknown precursor liquid matches the reaction speed of the test liquid during the gold-filled process. Now, in the titration of a test liquid having a titration curve (a) as shown in the vJj diagram, the titrant is Δ
It takes time Δtln(sea) for the electric potential E to change from point A to point B when only 4 min is dropped, and it takes time Δtln (sea) for the electric potential E to change from point A to point B, and from point B where the drop is stopped to 0 point where it is stable at τ.
If it takes 7t2n (sea), then the titration in the interval from point A to point 0 is the amount of change in potential DA, which is D.
It is expressed as A-='”'”/7e, y, and the amount of potential change X with respect to the opening during reaction is determined by b Speed is from point A above to CA
Since it approximates the (n) interval up to n+1
In order to approximate the total reaction rate of the dripping speed of the liquid in the interval button, the dripping speed Fn+1 of the next n-4-1 section is n-1-1 at this dripping speed Fn+1. When titration is carried out in the interval of
n+1 and 1 line z′・χ/); 1 Terama 7 until stabilization
t2n+1 is obtained. Therefore, next time・″)Q+
The same feedback system 9JIlI can be used for the second section, and the process is repeated from the beginning of the titration to the titration end point (electrode', the first position is i). r: A point corresponding to point H '1-u), a filter feed grasshopper control system can be created in the second method.

The above feed batter 1iiIJ MI V Koyo 7'L, 11 [Speed Fn.

Fn+l and Fn-1-2@fist are the reaction speeds at each point in the titration curve T gland, and are the same as 1F, which is 4 times the nearest 1.
(Feed batter! When repeating ljJ control for 1 μm, the potential E is calculated after each section is dropped, and the υ time Δt2n, Δ2n-14, ... becomes zero at J. Near < ) ri4 constant is along the titration LLJid jF
Ministry of Speedo'? J1. It matches the speed of thrift. If the initial 4-lower speed is slower than the reaction speed of the test liquid, the time Δt2n until the electrode potential E stabilizes becomes zero, and the above-mentioned follow-up excitation is not achieved. In this case, K>1 (for example, 1.1) and the dropping speed Fn44 is made to follow the reaction rate. And Δt2n
) When it becomes O, it can be determined that the delay has disappeared, and the titration is continued with the value set as 1.

Execute the above titration method on an unknown test sample M, and calculate the minute potential
Detect o = "/, t. This value XO can be set as the above-mentioned 1 loaf and 1 when the method of the present invention is executed for the same type of hex.

It is possible to perform titration quickly and easily.

[Brief explanation of the drawing]

Is Figure 7 the overall shape of a general establishment curve? Figure 1 is a schematic diagram showing an example of automatic retrieval system used to implement the present invention, and Figure 3 is a diagram showing the goal of feedback control 1 (tl! It is a titration curve diagram illustrating an example of a titration method for determining +1i...container, (2)... test liquid, (3)... detection electrode, (4)... reference electrode, (51...・Titration nozzle, (8
)...+1ilJ u equipment 1t91/Φ titration piston buret, [0)...buret driver. +1-f Kyoda Juniri Kyoto Denshi Riku 1 Kushiki Company fYZ~
1st generation Weirman Yenokyo Province
7i・jto, 2. -].

Claims (1)

[Claims] +11 Drop the titrant into the test liquid, electrically detect the change in the titration system, and use the electrical signal to determine the amount of minute potential change X=7 E n 7Δtn with respect to the minute drop time at a predetermined predetermined value. 1. A titration control method, characterized in that the dropping speed of the titrant is feedback-controlled so as to match the titrant value.