JPS6379039A - Suspension concentration measurement - Google Patents

Abstract

PURPOSE:To enable the measuring of the concentration of a suspension at a high accuracy, by irradiating a liquid containing a suspension with light through a signal glass to measure the intensity of the reflected light thereof for collation with a know value. CONSTITUTION:A fermentation liquid 11 is irradiated with light from a light irradiating section in probe 3 through a signal glass provided on a side wall of a fermentation tank 12 and the intensity of the reflected light thereof is received with a light receiving section in the probe 3 to be collated with a known value by a light irradiation analysis unit 4 whereby the concentration of cell in the fermentation liquid is measured. The concentration of cell in the fermentation liquid 11 is kept at a reference value by such an operation as increasing or decreasing the revolutions of a motor 61 via a converter 51 according to the degree of deviation of a measured value from a reference operation value or increasing or decreasing feed of air to an air dispersion tube 7 with the control of valve 71 via a converter 53. The concentration of cell in the fermentation liquid 11 is displayed on a cell densitometer 8 via a converter 52.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention Industrial Application Field This invention relates to a method for measuring the concentration of suspended matter in a liquid, and relates to a method for measuring the concentration of suspended matter in a liquid, such as a fermentation tank, an animal It is effective for maintaining and managing proper operating conditions in cell culture tanks, plant cell culture tanks, sewage treatment tanks, etc.

Conventional techniques Conventional methods for measuring the concentration of a suspension, such as cell concentration, include ■turbidity method and ■indirect measurement method, but ■1 turbidity method uses transmitted light. Indirect measurement method estimates suspension concentration by measuring components in cells (II) NA, RNA, ATP, NAD (P)H, and protein T. N
Although there is currently a method for measuring AD (P)H using fluorescence, it has the disadvantage that it is not direct and a uniform correlation cannot be established for all suspended substances. In addition, there are the ■specific gravity method and the [Co.] viscosity method, but the ■specific gravity method has a large error, and the ■viscosity method requires temperature correction, has a large error in the low concentration range, and is affected by antifoaming agents. big.

Others - As a counterargument, the range of generally reliable measurements is narrow, and operations such as dilution may be necessary.
Even with the online version, there is a limit to reliability because the sensor is in contact with the liquid contained in it, so sensitivity decreases due to dirt on the sensor surface, and there is a limit to reliability. '/l, sterilization is time-consuming, and the tank is susceptible to bacterial contamination due to insufficient cleaning and sterilization.If it is impossible to use online, sample and analyze a portion of the liquid. Therefore, measurement takes time and manpower. ■On-line methods have the disadvantage that they are easily affected by bubbles in the liquid they contain.

Problems to be Solved by the Invention It is an object of the present invention to provide a method for measuring the concentration of suspended matter in a liquid, which solves the drawbacks of the conventional methods as described above.

1. Means for Solving Problems in the Structure of the Invention The method for measuring the concentration of suspended solids according to the present invention involves irradiating a suspension-containing liquid with light through a sight glass and measuring the intensity of the reflected light. It is characterized by matching with a value.

This can be explained using Figure 1 using cell culture fluid as an example.
Light is irradiated through a sight glass 2 to a container holding a cell culture solution or a cover 1 in a tube 1 through which the cell culture solution is flowing, and the light receiving section 32 receives the reflected light.

Although light irradiation may be performed by a light source provided separately from the light receiving section 32, it is convenient to use a probe 3 having a structure in which the light irradiating section 31 and the light receiving section 32 are integrated.

In such a probe 3, the light from the lamp 33 is sent to the light irradiation section 31 through the optical fiber 34, and is irradiated into the container or tube 1 through the sight glass 2. The reflected light is captured by the light receiving section 32, and is transmitted through the optical fiber 35. Sent to the light irradiation analysis unit. A light irradiation analysis unit (indicated by symbol 4 in FIG. 2) measures the intensity of the reflected light and compares it with known values.

The intensity of reflected light from the cell culture medium has a linear proportional relationship with the cell concentration in the cell culture medium, as described below. Cell concentration can be easily determined.

For example, as the culture changes over time, samples are appropriately collected, diluted cell suspensions are prepared in several stages, and the absolute amount of cells is measured in advance.1The correlation between the reflectance and the absolute amount of cells is Determine a calibration curve Next, measure the reflectance of the liquid to be measured and compare it with the calibration curve to determine the degree of cell e in the liquid.

Generally, the reflectance of a blank sheet of paper can be used as a reference when measuring reflectance, but if the cells are colored or the medium is colored, A suspension with the maximum concentration of 3J may be prepared and its reflectance may be used as a reference.

Even if the Ig culture solution is dispersed by blowing air into it, the measurement can be performed without being significantly affected by air bubbles, but by taking an appropriate reference, the measured values can be obtained with high accuracy.

For example, a culture solution containing air bubbles is appropriately sampled, diluted cell suspensions are prepared in several stages as described above, the absolute amount of cells is measured, and the cells in the solution to be measured are determined based on the prepared calibration curve. Concentration can be determined.

The angle at which light is irradiated into the tank or tube is suitably 20 degrees to 80 degrees, preferably around 45 degrees with respect to the sight glass surface.

If it is at a right angle (90 degrees), the reflected light from the sight glass will be too strong, making the difference in reflectance unclear; if it is less than 20 degrees, the reflected light from inside the tank will be too weak, making measurement difficult.

The cell concentration measurement method of the present invention may be applied to the cell-containing tank itself or to the culture fluid flowing out from the cell-containing tank, but - as an example, it may be applied to the fermenter itself to ensure proper operating conditions. The case where it is applied as a means for maintenance and management will be explained with reference to FIG.

Light is irradiated from the light irradiation part (31) in the probe 3 to the fermentation liquid 11- through the sight glass 2 provided on the side wall of the fermentation tank 12, and the intensity of the reflected light is measured by the light reception part (31) in the probe 3.
2), and the light irradiation analysis unit 4 measures the cell concentration in the fermentation liquid by comparing it with a known value.

Depending on the degree of deviation from the standard value, the number of revolutions of the motor 61 of the agitator 6 is increased or decreased through the converter 51, or the valve 71 is controlled through the converter 53 to air By increasing or decreasing the number of air supply parts to the dispersion tube 7, the cell concentration in one fermentation liquid can be maintained at a reference value. will be displayed.

The light source used in the present invention is one that can irradiate enough light so that the reflected light from the turbid object when irradiated with light is strong enough to be detected as a signal.

An appropriate light source may be used depending on the concentration range of the suspended matter to be measured.

It is desirable to use a high output light source, such as a halogen tungsten lamp, and irradiate the light with high illuminance so that even if the concentration of suspended matter is high, it can be directly measured without dilution.

It is preferable to use a high illuminance of 10,000 lux or more. If the concentration of suspended matter is lower than this, the reflected light from the liquid will become weaker and noise will increase, making measurement difficult. Since increasing the power consumption is accompanied by an increase in power consumption, a range of 10,000 to 300,000 lux is usually preferable, and a range of 1 to 250,000 lux is more preferable.

Moreover, the wavelength of the light used for measurement may be appropriately selected depending on the properties of the suspension and liquid to be measured.

[Example 1] Maximum 77 dry cell g/1. Minimum 1.3 dry cell g/
Prepare the ii:ta yeast solution for each stage in the high and medium concentration regions of the room, place it in a spectrophotometer cell, and irradiate the glass surface of the cell with light from a 45 degree angle. Table 1 shows the results of measuring the reflectance.

A halogen tungsten lamp was used as a light source, and light was irradiated so that the intensity on the glass surface of the cell was 180,000 lux.

The highest concentration, 77 g/dry cell, was used as a reference.

Further, in Table 1, the relationship between the reflectance of light at a wavelength of 660 nm and the yeast concentration is shown in FIG. Here, the horizontal axis shows the yeast concentration (dry cell g/mon), and the vertical axis shows the reflectance (%).

As is clear from Table 1 and Figure 3, there is a linear proportional relationship between yeast concentration and light reflectance. Another 77 dry cell g/! It can be seen that even a high concentration as high as L can be measured without dilution.

[Example 2] A yeast culture solution containing 33 g/l of dry cells was used as a stock solution and diluted with a medium to prepare yeast solutions at each stage in the medium concentration range up to a minimum of 3.35 g/l of dry cells, and put into test tubes. ,
Light was irradiated onto the glass surface from an angle of 45 degrees, and the reflectance was measured.

The results are shown in Table 2. A blank sheet of paper was used as a reference.

Furthermore, in Table 2, the relationship between the reflectance of light at a wavelength of 660 nm and the yeast concentration is shown in FIG. Here, the horizontal axis shows the yeast concentration (dry cell g/vertical), and the vertical axis shows the reflectance (%).

As is clear from FIG. 4, there is a linear proportional relationship between the yeast concentration and the light reflectance even in the medium C degree region.

Table 2 [Example 31 Same as the example process, maximum 3.1 dry cell g/l,
Prepare a yeast solution at each stage in the low concentration range of at least 0.031 g/l dry cell, place it in a spectrophotometer cell, and irradiate the glass surface of the cell with light at a 45 degree angle. Table 3 shows the results of measuring the reflectance.

The reference is the highest concentration of 3.1 g/dry cell.
Sentences were used.

Furthermore, in Table 3, the relationship between the reflectance of light at a wavelength of 660 nm and the yeast concentration is shown in FIG. Here, the horizontal axis shows the yeast concentration (dry cell g/L), and the vertical axis shows the reflectance (%).

As is clear from Fig. 5, even in the low concentration region.

A linear proportional relationship is observed between yeast concentration and light reflectance Hn.

Table 3 C0 Effects of the Invention Highly reliable measurement values can be obtained for a wide range of suspended matter concentrations, and the measurement range can be adjusted to high, medium, and low concentration areas as necessary. Highly accurate concentration measurement can be performed by switching.

It is quick and easy, has little influence from changes in temperature, specific gravity, and viscosity, does not require washing or sterilizing the sensor, does not have the risk of bacterial contamination of the culture solution, and can easily compensate for the effects of air bubbles. It is effective for maintaining and managing proper operating conditions in fermenters, tanks containing animal cells, tanks containing plant cells, etc.

Further, the present invention can be implemented without making any special modifications to an existing tank having a sight glass.

[Brief explanation of the drawing]

Figure 1 is a diagram for explaining the method of implementing the present invention, Figure 2 is an explanatory diagram when the present invention is applied as a means for maintaining and managing appropriate operating conditions in a fermenter, Figures 3, 4, and FIG. 5 is a diagram showing test results according to the present invention. 1... Wall of container or tube, 11... Cell culture medium. 12... Fermentation tank, 2... Sight glass, 3... Probe, 31... Light irradiation section, 32... Light receiving section, 33
...Lamp, 34.35...Optical fiber, 4...Light irradiation analysis unit, 51.52.53...Converter,

Claims (1)

[Claims] 1. Irradiating a suspension-containing liquid with light through a sight glass,
A suspension concentration measurement method characterized by measuring the intensity of the reflected light and comparing it with a known value. 2. The suspension concentration measuring method according to claim 1, wherein the suspension-containing liquid is irradiated with light at an illuminance of 10,000 lux or more. 3 Adjust the angle at which the light is irradiated onto the liquid by 2 with respect to the sight glass surface.
The suspension concentration measuring method according to claim 1 or 2, wherein the temperature is 0 degrees to 80 degrees.