JPH0465970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for automatically colorimetrically analyzing components in a test liquid containing components that change over time.

(Prior art) Conventionally, when the content of trace components contained in a continuously flowing liquid changes over time, the sample is sampled and subjected to colorimetric analysis to examine the state of the change over time. There were various problems.

For example, when automatically measuring trace components on the order of ppb, if the line through which the test liquid passes is not thoroughly cleaned, the analytical values will be extremely unreliable due to the influence of residual liquid from the previous analysis. . In addition, operations such as collection of the test liquid, colorimetric analysis of the liquid after color development by mixing it with a drug such as a coloring agent, and the above-mentioned washing must be performed quickly in order to accurately understand the changes in the test component over time.
Conventionally, these processes have not been performed systematically, and each has been performed individually and manually, resulting in extremely poor efficiency and a need for improvement.

(Objective of the Invention) The object of the present invention is to provide an apparatus that systematically assembles a series of operations such as sampling a test liquid, mixing it with a drug, colorimetric analysis, and cleaning, in order to analyze trace components that change over time. The purpose of this invention is to provide a highly reliable and industrially useful automatic colorimetric analysis method.

(Structure of the Invention) In other words, the present invention, when measuring the changing components of a test liquid whose components change over time using a colorimeter, samples a certain amount of the test liquid at regular intervals, and produces a certain amount of color. It is introduced into a colorimetric device together with the agent and other buffering agents, stabilized by circulation for a certain period of time in the colorimetric device, and automatically analyzed with a colorimeter after degassing. After draining the liquid and cleaning the colorimetric device for a certain period of time, an automatic method characterized by sampling a certain amount of the test liquid again, repeating the previous measurement, and digitizing and displaying the colorimetric measurement values during this operation. It is a colorimetric analysis method.

The method of the present invention will be explained with reference to the drawings. An unpurified liquid is passed through a purification column 2 from a tube 1, purified, and sent to the next step through tubes 3 and 4 as a test liquid containing a trace amount of fluctuating components. Note that 2' is a preliminary purification tank that can be switched to when the exchange capacity of the purification tower 2 is insufficient. A portion of it is led to a receiver 6 through a valve 5 as a sampling liquid. Preferably, this liquid is continuously supplied and allowed to overflow from the pipe 7 to replace the old liquid. A fixed amount of the sampling liquid is introduced into a mixing tank 9 by a metering pump 8 via a valve V ₁ and a valve V ₂ . 10 is a soft water tank for washing, and a mixing tank 9 is also supplied by a metering pump 8.
guided by. Further, 11 is a coloring liquid tank, and 12 is a buffering chemical liquid tank, and the coloring liquid and the buffering chemical liquid are introduced into the mixing tank 9 by metering pumps 13 and 14, respectively. These valves and pumps are controlled by a microcomputer to adjust the amount of liquid sent to the mixing tank.

The mixing tank 9 is capable of rotating at low and high speeds by a motor 15, and is rotated at a low speed to mix the liquid in the tank for an appropriate time and sufficiently color the sampling liquid. Next, this liquid is circulated through pump 1
8 through pipes 19 and 20 to a colorimetric device consisting of a filter 21, a gas-liquid separation tank 22, and a colorimetric tank 23, and returned to the mixing tank through pipes 24 and 25 and circulated for a predetermined period of time to check the state of the liquid. After stabilization, colorimetric tank 2
3, the absorbance of the liquid at a certain wavelength is measured by the colorimeter 26. The gas-liquid separation tank ₂₃ is provided to remove gas in the circulating fluid that causes measurement errors and to stabilize the fluid. released. The filter 21 is effective for removing precipitates generated depending on the type of liquid, but may be omitted if no precipitates are observed.

When the analysis is completed, the mixing tank 9 is rotated at high speed, and the post-analysis liquid is caused to overflow from the tank wall into the external tank 16 and is discharged from the system through the pipe 17. Next, the cleaning water from the cleaning soft water tank 10 is led to the mixing tank 9 by the pump 8, and the tank is rotated at low speed to thoroughly clean the inside of the tank, and this cleaning water is circulated to the colorimetric device by the circulation pump 18 for cleaning. do.
The cleaning water returned to the mixing tank 9 rotates the mixing tank 9 at high speed to overflow and is discharged from the pipe 17. The circulating fluid can also be discharged into the pipe 27 through the valve _V4 .

These operations will be explained in detail below.

Although the purification towers 2 and 2' are effective in removing most of salt water, hard water, etc. containing calcium, they are not always necessary depending on the type of liquid to be tested. A plurality of sampling liquid receivers 6, for example 6', may be installed, and these can be used as preliminary receivers to collect sampling liquid from _any part of the test liquid. This makes it possible to analyze such samples. The sampling liquid is transferred to the receiver 6, as described above.
It is preferable to allow continuous overflow of the test liquid from 6', since the test liquid can be collected continuously. However, if the liquid is directly sent from the pipe 28 to the mixing tank 9 without providing such a receiver, in this case, a timer is set on the valve 5. The liquid may be fed intermittently by a certain amount by interlocking the above. The colorimetric tank 23 is a flow cell capable of automatically supplying and discharging circulating fluid, and the measurement data from the spectrophotometer installed therein is converted into A/D.
The converter 29 converts from analog to digital, and the microcomputer 30 stores and calculates the values, and displays the results on a display and outputs them using a printer.

In this case, one of the sampled solutions should be used as a standard solution for another precise analysis, such as ICP.
After measurement by atomic absorption spectrophotometry or the like, the absorbance is measured and compared with a blank solution to obtain a calibration curve, which is stored in the microcomputer 30. By comparing the values of this reference liquid and other sampling liquids, accurate measurement becomes possible.

This microcomputer 30 has a pump 8,
13, 14, and 18, and the operating time, opening and closing of valves 5, _V1 , _V2 , and _V3 , and measuring the time, starting the motor 15 that rotates the mixing tank 9,
A series of operating programs such as stopping, changing the speed of high-speed rotation and low-speed rotation, and measuring the time are given, and the sampling amount and time of the test liquid, coloring agent, and buffering agent are determined. The addition amount and addition time, the circulation time of the colorimetric device, the rotation time of the mixing tank, the amount of washing water fed, the washing time, etc. can be quantified.

(Effects of the Invention) According to the method of the present invention, sampling of the test liquid from the flow path, addition of coloring solution, buffer solution, etc., mixing and circulation of these in the colorimetric device, colorimetric measurement, device cleaning with washing water, etc. By automating a series of repeated operations using a microcomputer, etc., labor can be saved and the operations can be performed rationally. In addition, since the colorimetric measurement values are digitized and input into a computer and displayed, it is possible to easily know the fluctuations in trace components in the test liquid. Circulation in the colorimetric device of the present invention is effective for stabilizing the liquid, and in particular, if solids are present in the test liquid, they can be removed by providing a filter during the circulation process. In addition, if the mixing tank is designed to be able to rotate, cleaning operations and mixing of chemical solutions can be carried out, and since the liquid extraction pump is not directly connected to the mixing tank, there is no possibility that the sampling liquid will remain in the tank or piping. Accurate analysis can be performed without affecting subsequent measurements.

Example The concentration of calcium ions (Ca ⁺⁺ ) in saturated salt water was measured using the automatic analyzer shown in FIG.

First, perform the following operations to calculate the analysis span (conversion coefficient). Parasma emission analysis results
Saturated salt water containing 195 ppb of Ca ⁺⁺ was placed in a mixing tank, a coloring solution and a buffer were added thereto, and after being circulated through the colorimetric device shown in Figure 1 to stabilize it, the absorbance was measured and a value of 0.469 was obtained. After discharging this, send the same salt water to the mixing tank.
Add an amount of reagent EDTA to completely hide Ca ⁺⁺
This was used as a blank solution for Ca ⁺⁺ . This liquid was circulated through the colorimeter in the same manner as above and the absorbance was measured to be 0.304. From these two absorbances
The coefficient for calculating Ca ⁺⁺ is stored in the microcomputer 30 as 195×1/(0.469−0.304)=1.182×10 ³ .

() Measurement Saturated brine sent to the electrolytic cell in the soda electrolysis process is passed through pipe 1 to purification tower 2 filled with chelate resin.
The test solution is salt water from which most of the Ca ⁺⁺ and Mg ⁺⁺ have been removed.

A portion of the brine at the outlet of the purification tower is constantly overflowed into a receiver 6 having a capacity of about 1 at a flow rate of 5/hr to keep the receiver constantly filled with fresh brine.
The salt water in this receiver is pumped to 100% by metering pump 8.
It is sent to the mixing tank 9 for 1 minute at a rate of ml/min. Note that the above operations and the following operations described below are all automatically controlled by the microcomputer 30. Next, the luminescent liquid from the luminescent liquid tank 11 is sent to the mixing tank 9 at a rate of 20 ml/min, and the buffer solution (alkali hydroxide) from the buffer tank 12 is sent to the mixing tank 9 by the metering pump 14 at a rate of 20 ml/min. Rotate at low speed (approximately 300 rpm) for 5 minutes to thoroughly stir and develop color. This colored liquid is transferred to a gas-liquid separation tank 22 and a colorimetric tank 2 using a circulation pump 18.
After the liquid in the colorimetric tank was sufficiently stabilized by circulating for 3 minutes, the circulation pump 18 was stopped. The absorbance is measured by a colorimeter 26 and its value is designated as A. Next, mix tank 9 is rotated at high speed (approximately 1200 rpm)
Drain the liquid in the tank.

Next, the salt water in the receiver 6 is again sent to the same 100 ml mixing tank 9 by the metering pump 8. Then Ca ⁺⁺
Pump an amount of the reagent EDTA from a storage tank (not shown) to a mixing tank 9 to completely hide the
Further, the colorimetric solution, the buffer solution, the mixing of these solutions, and the circulation operation of the colorimetric device are carried out in exactly the same manner as described above, and the absorbance is measured, and the value is designated as B.

From the values and coefficients of A and B, Ca ⁺⁺ in the salt water
The concentration C is C=(A-B)×1.182×10 ³ ppb, and this value is calculated by the microcomputer 30.
After the calculation is performed, it is stored in the printer and displayed on the display.

() Cleaning The mixing tank 9 is rotated at high speed to discharge the measured amount of salt water, and then the metering pump 8 is pumped from the cleaning soft water tank 10.
200c.c. of water is sent to the mixing tank, rotated at low speed for 2 minutes to clean the inside of the tank, and then rotated at high speed to drain the water. Next, water is again sent from the cleaning soft water tank to the mixing tank and circulated within the colorimetric device for 2 minutes by the circulation pump 18. After washing, water is drained from the mixing tank in the same manner.

The above measurement and washing operations () and () were repeated under computer control, and the Ca ⁺⁺ concentration was automatically measured at regular intervals. The results are shown in FIG.

As is clear from Fig. 2, while the chelate resin-filled purification tower 2 still has sufficient exchange capacity for Ca ⁺⁺ contained in the brine, the Ca ⁺⁺ concentration at the outlet of the purification tower shows a sufficiently low value. However, as the capacity declines, a state in which the Ca ⁺⁺ concentration rapidly increases over time is often detected.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing an embodiment of the method of the present invention, and FIG. 2 is a graph showing changes in calcium ion concentration over time in Examples. 6, 6'... Sampling liquid receiver, 9... Mixing tank, 10... Soft water tank for cleaning, 11... Coloring liquid tank,
12...Buffer tank, 18...Circulation pump, 22...
...gas-liquid separation tank, 23...colorimetric tank, 30...microcomputer.

Claims (1)

[Scope of Claims] 1. When measuring the changing components of a test liquid whose components change over time using a colorimeter, a certain amount of the test liquid is sampled at certain time intervals, and a certain amount of coloring agent and It is introduced into a colorimetric device along with other buffering agents, stabilized by circulation for a certain period of time in the colorimetric device, and automatically analyzed with a colorimeter after degassing. After draining and cleaning the colorimetric device for a certain period of time, a certain amount of the test liquid is sampled again and the measurement is repeated, and the colorimetric measurement value during this operation is digitized and displayed. Analysis method. 2. The method according to claim 1, wherein the colorimetric device has a liquid circulation path from the mixing tank through the gas-liquid separation tank and the colorimetric tank and back to the mixing tank. 3. The method according to claim 2, wherein a filter is provided in the liquid circulation path between the mixing tank and the gas-liquid separation tank. 4. The method according to claim 2, wherein the mixing tank is a tank that rotates at least two speeds, low speed and high speed, and is provided with a pump that pumps up the liquid in the tank from the upper part and guides it to the liquid circulation path. . 5. The method according to claim 1, wherein the sampling is performed by continuously supplying the test liquid to the sample receiving tank and allowing excess liquid to overflow.