JPS6013135B2 - Method for measuring volatile components in solid dispersions - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the concentration of volatile components in a solid dispersion, and is aimed at rapid and accurate measurement.

In a solid dispersion liquid, for example, a microbial culture system, it is extremely important to measure the concentration of the main carbon source, other constituent components, and metabolic products, and the amount of change in concentration in controlling the culture.

In general, volatile components in the culture solution, such as alcohols, aldehydes, Kents, organic acids, mercaptans, lower hydrocarbons, etc. Therefore, it has been strongly desired to develop a method for quickly and accurately measuring the concentration of volatile components in a microbial culture solution. The same applies to volatile components in latex in which polymers such as oligomers are suspended. However, the solid dispersion is a system in which solid matter is mixed in the liquid, making the above measurement extremely difficult.

The conventional measurement method was to first centrifuge the sampled liquid to remove the solid content, and then apply a certain amount of the supernatant liquid to a gas chromatograph to measure the concentration of the target component. . Therefore, after sampling,
There was a drawback that there was usually a delay of about 13 minutes until the measurement results were obtained, and that the measurement required manual labor. On the other hand, for example, if the purpose is to automate the management of a microbial culture system, it is natural to automate the process of measuring the concentration of volatile components in the culture solution as an index necessary for management using the conventional principle described above. A response delay of approximately 1 powder is expected, and a very complicated sampling device such as a solid matter removal device is required, which is extremely disadvantageous in terms of equipment.

Recently, in order to improve these shortcomings, a silicone tube is immersed in a culture solution, a certain amount of air is passed through the tube, and methanol (the main carbon source) that diffuses through the tube wall is detected using a gas chromatograph. A method for detecting and measuring the methanol concentration in the culture solution has been proposed.

Indeed, this method is superior in that it can omit the centrifugation process compared to the conventional method, saving time and effort.However, on the other hand, the silicone wall of the tube is It has a considerable resistance to the permeation of volatile components, and as a result, there is a delay in response of about 10 to 2 degrees to changes in methanol concentration in the culture solution, so this method also requires culture management. Therefore, the inventor of the present invention has conducted intensive research into a method for quickly and accurately measuring the concentration of volatile components in a solid dispersion in order to eliminate these drawbacks, and as a result has arrived at the present invention. .

The details of the present invention will be described below.

The method of the present invention uses a "hydrophobic porous tube, preferably a
A tube made of a porous material made of tetrafluoroethylene resin is immersed in a solid dispersion liquid, and a carrier gas is passed through the tube and guided to a measuring instrument, where it passes through a membrane and diffuses into the gas. Concentrations of volatile components in the neck continuously or intermittently.

This is a measurement method that is determined by The diagram below shows an outline of the flow of this device.

A carrier gas, such as nitrogen or helium, is preferably passed through the tube. Air may be used depending on the detector. Preferably, the pressure and flow rate of the gas are kept constant; for example, when a tube with an inner integral number of ribs is used, the flow rate of the gas is preferably kept constant at a value of about 40 to 80 cc'.

``The differential pressure between the gas passing through the tube and the solid dispersion liquid may be zero, or it may be pressurized or negative pressure. However, in the case of pressurization, if the pressure on the gas side to be vented is too high, porous This is undesirable because the gas will blow out into the solid dispersion through the holes in the tube.In short, the pressure should be maintained at a level that prevents gas from blowing out into the dispersion through the holes.Also, in the case of negative pressure, the pressure inside the tube The pressure difference between the gas passing through the tube and the dispersion liquid should be maintained at a negative pressure to the extent that the dispersion liquid does not flow through the tube hole and spill onto the inner wall of the tube in liquid form.Also, in the tube, the pressure loss of the gas is , the smaller the better, so it is preferable that the inner diameter of the tube be within the range of T.

The tube wall also needs to withstand a slight pressure difference.
On the other hand, if the wall is made thicker, the diffusion rate through the wall will decrease by 4 mm, so it is preferable to have a tube length of several hundred French. For example, for a tube with the above outer diameter, a length of 20 to 30 tubes is sufficient.In addition, the porous material of the peacock is suitable for dispersing bacterial cells in the liquid. In order to prevent clogging of materials, it is desirable that the particle size is smaller than that of the dispersion.For example, in the case of a culture solution for microorganisms, use a particle size of about 2 µm or less for yeast, etc., and about 1 µm or less for bacteria. It is preferable to use a gas chromatograph as the measuring instrument.If the gas contains multiple volatile components, a certain amount of the gas exiting the tube is sampled with a gas sampler, separated with a column, The amount of each can also be measured with a detector.

On the other hand, if the gas essentially contains only a single volatile component, there is no need to separate it using a column, and the gas exiting the tube is directly sent to the flame ionization detector. It can be detected by running it on the In this case, since no column or gas sampler is used, it is mechanically simple and data can be obtained continuously, making it an extremely popular measurement method for automatic control. Next, the dark piping from the tube to the measuring instrument is heated to a temperature higher than that of the solid dispersion in order to prevent response delays due to condensation or adsorption of volatile components.
Preferably, the temperature is maintained at 5° C. or more above the liquid temperature.

A feature of the present invention is that a hydrophobic porous membrane tube is used to quickly and continuously convert volatile components from a solid dispersion containing a mixture of solid and liquid into a gas that can be easily measured using a known measuring instrument, preferably a gas chromatograph. The purpose of this method is to measure the concentration of volatile components in the liquid using the above-mentioned measuring device by sampling periodically or intermittently using a simple mechanism. As mentioned above, measurement methods using silicon tubes have already been reported, but when comparing the mechanism by which volatile substances diffuse from the solid dispersion to the gas in the tube, in the case of silicon, it is found that Volatile substances dissolve and diffuse and move into the gas inside the tube, whereas in this method, volatile substances become gas and diffuse in the pores of a porous body, so the mechanism is completely different. The diffusion rate of the latter diffusion mechanism is significantly higher. The rate of diffusion of a volatile substance into a liquid phase separated by a hydrophobic porous material is expressed by the equation {1-.

The denominator of equation [1} is a term corresponding to the resistance to diffusion, and is composed of two elements: the first term, the resistance in the wave-side membrane, and the second term, the resistance when passing through the porous body-level pores. Consisting of

Generally, the second term is much smaller than the first term, and the total resistance of both terms is almost dominated by the first term, that is, the resistance in the liquid side boundary.

On the other hand, in the case of a silicon film, volatile components dissolve and diffuse in the film, and the resistance thereof is generally much larger than the resistance in the liquid-side boundary film. Therefore, when comparing the diffusion rates of a hydrophobic porous material and a silicon film, the former is dominated by the diffusion resistance due to the liquid-side boundary film, whereas the former is dominated by the dissolution diffusion resistance in the membrane, which is much larger than the liquid-side boundary film. The rate of diffusion is faster than the latter. In other words, it can be said that the former responds more slowly to changes in the concentration of volatile components in the liquid phase. . According to this method, which uses a tube material with a high diffusion rate, 90% response to changes in the concentration of volatile components in the solid dispersion is around 1 minute, which is faster than when using a silicone membrane. It exhibits a response speed of about 1 ping or more, which shows its remarkable superiority. Furthermore, for example, when a device to be immersed in a culture solution is required to have firstly heat resistance that can withstand normal heat sterilization, and secondly safety against foods and medicines, the tube material may be If a porous material such as tetrafluoroethylene is used, these conditions are fully satisfied, so the method of the present invention is excellent as an industrial measuring method.

Example 1 In order to measure the volatile components in the culture solution, the following culture experiment was carried out to measure the ethanol concentration in the culture solution.

Strain used: Saccharomyces cerevis
iae (baker's yeast) main carbon source and nutrient source: 30% glucose was the main carbon source, and other nutrient sources were as follows.

Sun 3P04 4000ppm FeS0417 Sun 20
200ppmKC〃 4000″ ZnS
04/7th 20 200 〃Mbee S〇4 4000〃
MnS〇4th and 6th 20 20″ Ammonium sulfate 50
0〃 CuS0405日20 4″NaCZ I
OO〃 Vitamin mixture 150〃CaCmu2
200 〃 Yeast Extract 1000''Culture conditions: Using a 301-volume jar fermenter, the temperature was 3300 and the pH was controlled with an ammonia aqueous solution to 4.5.The aeration rate was 20 NI/min, and the number of flies was 50 pm. After adding the above-mentioned nutritional sources other than glucose, glucose was supplied by an exponential fed-batch method.
The bacterial cell concentration was started at 1% (dry weight). Ethanol in the culture solution is originally a metabolic product of yeast, but in this experiment, in order to observe the step response of the measuring instrument, a fixed amount of ethanol was added intermittently every 3 minutes, and the response of the measured value was measured. I saw it.

Measurement method: Place a hydrophobic porous tube (made of tetrafluoroethylene resin, outer diameter 5, wall thickness 50, pore diameter 0) in a jar fermenter.
．． In autumn, soak the porosity of 30% as shown in Figure 1.
The gas exiting the tube was led to a flame ionization detector, and its output was continuously recorded (Figure 2).

Note that nitrogen gas was used as the carrier gas flowing into the tube, and the ventilation rate was 60 cc/min. In this case, the pressure difference between the gas and the culture solution was almost zero. As a result, as shown in FIG. 2, it was found that there was a good response to the step-like concentration change of ethanol in the culture solution, with a 90% response of about 40 to 5 centimeters.

Furthermore, the ethanol concentration in the culture solution and the output of the detector have a linear relationship as shown in FIG. 3, and are sufficiently quantitative.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the measuring method of the present invention, FIG. 2 is a graph showing the response to a step-like change in the ethanol concentration in the solid dispersion (yeast culture solution) of the present invention, and FIG. 3 is a graph showing the response to a step change in the ethanol concentration. It is a graph showing the relationship between and the detector output (peak height). DESCRIPTION OF SYMBOLS 1... Solid dispersion liquid, 2... Hydrophobic porous tube, 3... Measuring device, 4... Carrier gas. Ge Z Chest Shio Z Box 312

Claims (1)

[Claims] 1. Immersing a hydrophobic porous tube in a solid dispersion,
A carrier gas is passed through this tube, and the gas is guided to a measuring device to detect the amount of volatile components in the solid dispersion that permeate through the membrane of the tube and diffuse into the gas. A measurement method that measures the concentration of volatile components continuously or intermittently. 2. The measuring method according to claim 1, wherein the tube material is a porous membrane made of tetrafluoroethylene resin. 3. The measuring method according to claim 1, wherein the solid dispersion is a culture solution of microorganisms. 4. The measuring method according to claim 1, wherein the solid dispersion is a latex in which a polymer such as an oligomer is suspended. 5. The measuring method according to claim 1, wherein the carrier gas is nitrogen. 6. The measuring method according to claim 1, wherein the carrier gas is helium. 7. The measuring method according to claim 1, wherein the differential pressure between the carrier gas and the solid dispersion is zero. 8. The measuring method according to claim 1, wherein the pressure is maintained to an extent that gas does not blow out into the solid dispersion. 9. The measuring method according to claim 1, in which the solid dispersion is maintained at a negative pressure to the extent that it does not ooze out in liquid form onto the inner wall of the tube. 10. The measuring method according to claim 1, wherein the amount of volatile components diffused into the carrier gas is intermittently measured using a gas chromatograph. 11 A patent for continuously measuring the concentration of a volatile component in a solid dispersion by detecting the amount of the volatile component in a gas using a flame ionization detector when the volatile component is substantially single. The measuring method according to claim 1. 12. The measuring method according to claim 1, in which the piping that conveys gas from the tube to the measuring device is maintained at a temperature higher than the temperature of the solid dispersion.