JPS582365B2 - Renzokushikihishiyokubunsekisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical measuring section for performing colorimetric measurements in a continuous colorimetric analyzer and its signal processing.

Generally, when attempting to perform automatic analysis of river water, industrial wastewater, etc. using a continuous colorimetric analyzer, the behavior of suspended solids within the flow cell causes serious errors in colorimetric measurements. Cause.

The influence of such suspended matter causes reflection and absorption phenomena when light travels within the flow cell, and is different from the absorption that originally occurs as a result of color development of a specific liquid-containing substance.

Furthermore, if suspended matter in the sample solution remains in the flow cell or adheres to the inner wall, it will cause a significant error in the measured value.

In order to eliminate the influence of such suspended substances, there is a method of continuously or periodically introducing air bubbles into the 7-row cell.

Generally, gas-liquid interfaces have strong adsorption properties, and by allowing air bubbles to flow into a conduit such as a flow cell, a cleaning effect is exerted and the accumulation of suspended matter can be easily eliminated.

However, it is clear that each time the bubble force blocks the optical path of the flow cell by introducing a bubble into the flow cell, a portion of the light beam from the light source is reflected and the amount of transmitted light varies greatly.

According to some reports, an auxiliary detector is installed in a part of the flow cell in order to eliminate the influence of light reflection from bubbles and to perform continuous and stable measurements. A method is used in which an indication is obtained from the transmitted light of only the sample liquid by checking in advance and electrically or mechanically holding the function of the amplifier circuit or indicator.

However, the installation of such an auxiliary detector has the disadvantage of complicating the device.

The present invention provides a measuring device that can obtain similar effects without using the aforementioned auxiliary detector.

That is, in the process of bubbles entering the optical path, the amount of transmitted light changes rapidly due to a reflection phenomenon at the interface between the liquid layer and the gas layer.

Therefore, by skillfully processing the initial transient signal output of the photodetector due to this phenomenon, bubbles can enter the optical path, eliminating the effect of bubbles on the colorimetric value, and allowing continuous and stable stagnation. I can do it.

Examples of the present invention will be described below.

In Figure 1, 1 is a light source lamp, 2 is a slit, 3 is a collimating lens, 4 is a monochromatic optical filter, 5 is a slit, 6 is a flow cell, 7 is a sample liquid, 8 is a bubble, and 9 is a light receiving detector. .

In Fig. 1, the luminous flux from the light source 1 is transmitted through the collimating lens 3,
A monochromatic optical filter 4 converts the light into a light beam of a specific wavelength, which enters the flow cell 6 .

Further, it is absorbed by the sample liquid 7, detected by the light receiving detector 9, and converted into an electrical signal.

As is well known, the absorption of light by the sample liquid and the concentration of the sample liquid have a relationship according to the Lambert-Beer law, and the concentration can be determined from the electric signal of the light receiving detector 9.

FIG. 2 is a diagram showing how the light is reflected when the bubble reaches the optical path in FIG. 1.

FIGS. 3 and 4 show examples of signal output waveforms of the light receiving detector from when the bubble reaches the optical path to when the bubble passes through the optical path.

Figure 3 shows the signal output waveform when the absorption by the sample is small, and Figure 4 shows the signal output waveform when the absorption by the sample is large. The horizontal axis is the time axis, and the vertical axis shows the signal intensity of the photodetector in arbitrary units. be.

Figure 4 shows a case where there is a lot of absorption by the sample, and when the bubble passes through the optical path, the output increases in the center because the light flux decreases due to the reflection phenomenon by the bubble, but a gas layer forms in the optical path. This is because the absorption decreases and the transmitted light flux increases compared to the case of using only the highly absorbing sample liquid.

Here, it is necessary to pay attention to the sudden change in the signal waveform indicated by A.

This is because the characteristics of the output waveform of the photodetector are an important element of the present invention.

As described above, the waveform at the instant when the bubble reaches the optical path always drops sharply from the signal output due to the sample liquid, regardless of the concentration of the sample liquid.

This phenomenon can be seen in Figure 2, where the upper part of the bubble clearly assumes a spherical shape due to surface tension, and at the moment it reaches the optical path, a part of the luminous flux from the light source is totally reflected, and the upper part of the bubble is temporarily spherical. This is based on the fact that it acts as a perfect absorber and the optical path is blocked.

FIG. 5 shows an example of the configuration of a continuous colorimetric analyzer to which the above principle is applied.

11 is a continuous colorimetric reaction device, 12 is a light source device, 13 is a flow cell, 14 is a photodetector, 15 is a preamplifier, 16 is a differential circuit, 17 is a monostable multivibrator, 18 is a switch circuit, and 19 is a sample hold circuit. , 20 is an indicator circuit, and 21 is a recorder.

In FIG. 5, the signal output of the photodetector 14 amplified by the preamplifier 15 is connected to a switch circuit 18, and one side is connected to a differentiation circuit 16.

In the differentiation circuit 16, a differentiation pulse is generated by the above-mentioned A waveform and triggers the monostable multivibrator 17.
The output of the monostable multi-bibreak 17 is connected to a switch circuit 8, and its period is set to the time required for at least one bubble to move along the optical path, which in this example is about 0.3 seconds.

The switch circuit 18 opens the switch when the monostable multivibrator 17 is in operation, and the preamplifier 1
5 is operated so as not to lead the output signal of No. 5 to the sample hold circuit 18.

In this way, the switch circuit 18 in the flow cell 13 is in the open state during the time when the bubbles are crossing the optical path.
The closed state occurs when the optical path is filled with sample liquid.

The operation of the sample and hold circuit 19 is similar to that of the switch circuit 1.
Since the signal immediately before the circuit 8 becomes open is held, the output of the hold circuit 19 always shows the value due to the sample liquid, and a stable recorder indication can be obtained.

FIG. 6 shows the operation waveforms of each part explained above, where a is the output voltage waveform of the preamplifier 15, b is the output voltage waveform of the differentiating circuit 16, C is the output voltage waveform of the monostable multi-vibration circuit 17, and d is the operation of the switch circuit 18. In the state diagram, e is the output voltage waveform of the sample and hold circuit 19.

Next, circuit operation will be explained.

The A signal received by the photodetector 14 is sent to the preamplifier 15.
and enters the switch circuit 18 and the differentiator circuit 16.

Since the switch circuit 18 is in an OFF state between the preamplifier 15 and the sample hold circuit 19, the instruction circuit 20,
The recorder 21 records no abnormal changes.

On the other hand, the differentiating circuit 16 generates a differential pulse signal b based on the signal waveform a of the preamplifier 15 and triggers the signal waveform C of the monostable multivibrator circuit 17.

The monostable multivibrator circuit 17 is normally held in a stable state, but as a trigger signal is applied by the differential pulse signal, the held state is reversed for a predetermined time period using a circuit constant, and the switch circuit 18 is turned on. (signal waveform d) A sample and hold circuit 191 is input.

The sample and hold circuit 19 is composed of an operational amplifier and a capacitor (not shown), and the input signal is sampled in a predetermined period and stored in the co-capacitor until the next sampling time. is instructed and recorded without any problems (signal waveform e).

The present invention is characterized in that the two operations of colorimetric measurement and bubble detection are performed by one light receiving detector, so there is no need to use other auxiliary equipment as in the prior art.

In addition, the signal waveform A, which captures the light reflection phenomenon at the interface between the liquid layer and the gas layer of bubbles passing through the flow cell, and rapidly changes in response to a sudden change in the amount of transmitted light, is adopted as the signal. When bubbles are passing through the flow cell and crossing the optical path, the switch circuit is opened and the non-measurement state is established, and when the flow cell is filled with sample liquid, the switch circuit is closed and the comparison is made. Since color measurement is performed, it is possible to reliably detect when a bubble passes, and even when a bubble passes, stable and highly accurate measurement can be performed.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams of the optical measuring section in the present invention, and Figures 3 and 4 are signal waveform diagrams of the photodetector, with the horizontal axis showing time and the vertical axis showing signal strength. . FIG. 5 is a block diagram of the apparatus of the present invention, and FIG. 6 is an operational waveform diagram of each part in the apparatus of the present invention. 6.13...Flow cell, 8...Bubble, 9,14.
... Light receiving detector, 16... Differential circuit, 18... Switch circuit.

Claims (1)

[Claims] 1 Bubble detection and colorimetric measurements are performed under conditions in which air bubbles flow into the flow cell along with the sample liquid, and the reflection of light at the interface between the liquid layer and air layer of the air bubbles passing through the flow cell is performed. One light-receiving detector 14 outputs a signal waveform A that captures a phenomenon and rapidly changes in response to a sudden change in the amount of transmitted light, and a differential pulse is generated by the signal waveform A from the light-receiving detector 14. Differentiating circuit 16 and differentiating circuit 16
The switch circuit 1 consists of a monostable multivibrator 17 connected to the photodetector 14 and a switch circuit 18 connected to the monostable multivibrator 17.
8 is a continuous type that is configured to open a switch when the monostable multivibrator is in an operating state to put it in a non-measuring state, and close the switch to perform colorimetric measurement when the monostable multivibrator is in an inactive state. Colorimetric analyzer.