JPS58169049A - Method and apparatus for measuring concentration of substance in liquid - Google Patents

Abstract

PURPOSE:To readily measure the concentration of a nonvaporizing substance in a liquid, by utilizing the fact that the vapor pressure of a vaporizing component in a liquid changes owing to the presence of a nonvaporizing substance. CONSTITUTION:Liquids containing a nonvaporizing substance at various concentrations are prepared, and a vaporizing component is added thereto until a predetermined concentration by volume is obtained, thereby to prepare test liquids. The vaporizing component concentration of the test liquids is measured under predetermined conditions by employing a tube method to obtain the calibration curve between the concentration and the vapor pressure of the vaporizing component beforehand. When the concentration of a nonvaporizing substance in a liquid 7 to be measured is actually measured, a vaporizing components is supplied into the liquid 7 from a supply device 11. By a system 1-6 for a tube method employing a carrier gas, the sensitivity to the vaporizing component is calculated in an arithmetic unit 23 from an output signal with respect to the concentration of the vaporizing component in the liquid 7, thereby allowing the concentration of the nonvaporizing substance in the liquid 7 to be made known from the calibration curve and the like stored in a memory 24.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for measuring the concentration of components in liquid, and particularly to the measurement of sugar content and salt content.

Conventionally, when measuring the sugar concentration in a culture solution of microorganisms, the culture solution of the microorganism is collected, the bacterial cells are removed by centrifugation, and then the supernatant is measured using methods such as the phenol/sulfuric acid method, the Nmogi method, the Bertrand method, or the enzyme reaction method. It has been measured using various methods. However, these measurement methods require complicated operations and processing, and usually take a considerable amount of time to measure one point.

The present invention provides a method and apparatus for quickly and easily measuring the concentration of sugar or salt present in a liquid by utilizing the fact that the vapor pressure of volatile components in the liquid changes depending on the presence of sugar or salt. It provides:

For some time now, in order to measure the concentration of vaporizable components in liquids, especially ethanol in microbial culture solutions, we have been using porous tubes with liquid repellency and continuous micropores in the tube method described below, which uses porous tubes. - developed and used measurement methods and devices. Vaporization in saliva using tube method 3+
In Boki's measurement method, a porous tube with liquid repellency and continuous micropores is immersed in the liquid to be measured, a certain amount of carrier gas is supplied to the porous tube, and the porous tube is passed through the tube. By guiding the carrier gas to the gas component detector,
The concentration of the volatile components in the rice saliva could be determined by passing the carrier gas from the liquid to be measured through the continuous micropores of the porous tube and detecting the volatile components in the rice saliva.

In this case, the amount of vaporizable components that permeate into the carrier gas through continuous micropores has a certain relationship with the vapor pressure, which is determined by the vapor-liquid equilibrium relationship that is influenced by the temperature, pressure, and components of the system. It is something that is in . Therefore, if the flow rate of the carrier gas is constant, and the system pressure, temperature, components other than the measurement target, etc. are constant, the concentration of vaporized water in the liquid to be measured is can be measured accurately by knowing the concentration of

On the other hand, if the concentration of a mixture of non-vaporizable substances that can be considered as a single substance such as molasses or molasses other than the component to be measured changes in the concentration of the mixture in the liquid to be measured, the vapor-liquid equilibrium relationship of the system changes. As a result, the vapor pressure of the component to be measured changes, and as a result, the amount of the vaporizable component that bends through the continuous micropores of the porous tube and permeates into the carrier gas changes.

The present inventor has discovered that when a non-vaporizable substance or a mixture thereof is mixed and dissolved in a liquid containing a vaporized component, the vaporization results in a concentrated concentration of the component, that is, the sensitivity changes greatly when measured by the tube method. and that there is a certain relationship between the concentration of non-vaporizable substances present in a liquid and the change in sensitivity of the concentration output of the vaporizable component in the liquid measured by the tube method.

The present inventor further measured the concentration of the vaporizable component in the liquid by the tube method based on the relationship between the concentration of the non-vaporizable substance in the liquid and the sensitivity change of the vaporizable component obtained in advance. We have invented a method and device for determining the concentration of non-vaporizable substances in a liquid by determining the sensitivity when

First, the measuring method of the present invention will be explained.

A liquid containing a non-vaporizable substance at various concentrations is prepared, a volatilizable component is added to the prepared liquid at a constant volume, and the mixture is used as a test liquid. It is called a test correction curve or correction table. Now, when actually measuring the concentration of non-vaporizable substances in a liquid, if the concentration of the volatile component in the liquid to be measured is known in advance, the tube method can be used to measure the concentration of non-vaporizable substances in the liquid to be measured. The sensitivity to the vaporizable component is calculated from the output signal for the vaporizable component concentration, and the θ value is calculated from the correction curve or correction table.
11 You can find out the concentration of non-vaporizable substances in your stomach.

Concentrated IO' of vaporizable components already present in the liquid to be measured
If X is not known in advance, first calculate this unknown concentration
Obtain the output signal a measured by the tube method. Next, a known amount of the volatile component is added and mixed into the liquid to be measured, and the concentration (x+y) of the volatile component in the liquid to be measured, including the increase in concentration y due to this, is measured by the tube method. Find the output signal. From the % (b-a) of the -th and second output signals, the output (
5'/j increase IJlli(b-a) is Judgment 9. From this, the sensitivity to vaporizable components by the tube method is calculated, and the concentration of non-vaporizable substances in the liquid to be measured is calculated from the calibration curve or correction table. can be known.

What must be noted in the above measurements is the components of the liquid to be measured and the test liquid used when creating the calibration curve. Not only the non-vaporizable substance and vaporizable component to be measured for both, but also other substances must be selected that contain exactly the same components. For example, when measuring glucose in a water-ethanol-glucose solution, the test solution must also be water-ethanol-glucose. To give a further example, when measuring the sugar concentration in a culture solution of a microorganism, the culture solution contains bacteria, culture medium, sugar, ethanol, etc. It is necessary to create samples that differ only in sugar content and create correction curves for them using the procedure described above.

Furthermore, one thing to be careful about in the above-mentioned measurements is that the conditions are required to be the same when creating the calibration curve and when measuring the non-vaporizable substance in the liquid to be measured. The temperature of the test liquid and the liquid to be measured must be the same, and the conditions for tube method measurement, such as the tube itself, the flow rate and pressure of the carrier gas, the sensitivity of the gas detector, etc., must be the same.

Regarding the temperature of the liquid, the change in the ejection force of the vaporizable component in response to the change in liquid temperature is determined in advance, and the liquid temperature is detected during measurement using the tube method, thereby correcting the influence of differences in liquid temperature. This is also an extremely easy and effective method.

Furthermore, for non-vaporizable substances to be measured, the tube method often does not have much selectivity for volatile components, such as sugars or salts. The best choice is one that is not detected itself but has a large effect on the vapor-liquid equilibrium of the liquid that conceals the volatile components. In particular, sugars such as glucose, sucrose, sucrose, and molasses in aqueous solutions, microbial culture solutions, and alcoholic beverages,
Salts such as table salt and sodium glutamate, sugars and salts in seasonings such as soy sauce and mirin are suitable as measurement targets.

Next, an apparatus for implementing this measurement method will be explained with reference to FIG.

A carrier gas supply section (2) is connected to one end of a porous tube (1) having liquid repellency and continuous micropores through a carrier gas supply conduit (3). The other end of the porous tube (1) is connected to a detector (
5) is connected. (6) is a heater that heats the carrier gas discharge conduit (4) to a temperature higher than that of the liquid to be measured (7). 0 is a stock solution tank that stores the stock solution 03 of the liquid to be measured, 0x is a pump that transfers the stock solution to the measurement container αG, and αB is a pump that supplies a fixed amount or constant flow rate of vaporizable components into the measurement container 00. This is a vaporizable component supply device.

Also, instead of stirring and mixing and measuring in the measurement container, the stock solution tank U
A "mixing container" may be separately provided between a and the measurement container αG for storing the liquid to be measured and supplying and mixing the vaporizable component thereto. This has the effect that when different measurements are repeated several times in succession, switching can be done quickly and the mixing time can be shortened.

The measurement container αG includes a liquid stirring device and temperature control 11.
α7). The measurement container αe accommodates a porous tube (1) and a liquid temperature detection end, and contains the measurement liquid. Barrel 0 is a discharge valve installed in a discharge line (a) for discharging the measured liquid after measurement, and barrel 01 is a waste liquid tank.

(C) is a calculation unit that calculates the sensitivity from the output signal from the detector (5) and calculates the It has a function of calculating the value of a vaporizable substance and displaying the result on the display section or outputting it to the output section.

Furthermore, the calculation section (c) includes a liquid@funeral detection terminal and a temperature converter (
It is also effective to use a sensor having a function of performing correction calculations for changes in the detector output signal due to changes in the temperature of the liquid to be measured based on the liquid temperature change signal obtained in step (c). In addition, the stock solution transfer pump 04), vaporizable component supply device (ID
It is also effective to provide a function to control the operation of the liquid to be measured, the discharge valve α8), etc.

Judging from these staff members, it is thought that the optimal computing department would be one that utilizes a computer.

The liquid may be moved batchwise or continuously.

That is, a certain amount of the liquid to be measured undiluted solution 03 is transferred to the measurement container OG, then a certain amount of the volatile component is added, the mixture is thoroughly stirred, the sensitivity of the volatile component is measured, and the entire amount is discharged to complete one cycle. finish. Alternatively, the liquid to be measured is transferred to the measurement container αG and discharged from the measurement container 0Q at a constant flow rate, and the vaporizable component is added at a strictly constant ratio to the flow rate of the stock solution of the liquid to be measured, By mixing, non-vaporizable substances can also be measured continuously. In this case, it is necessary to pay attention to the measurement container α0 and the transfer flow rate of the liquid to be measured so as to be able to perform rapid continuous measurements with as fast a response as possible. Temperature tw 0 regulator aη is measurement container 0
This is to keep the temperature of the 0 and the liquid inside it constant. The vaporizable component supply device G should be one that uses a metering pump or a metered drop type using gravity, or in the case of batch delivery, one that supplies the vaporizable component in electricity by the operation of an electric valve. Can be done. Liquid transfer device Q4)
It is also possible to use a combination of a fixed amount drop due to gravity and a (electromagnetic) valve.

For the porous tube (1), a tube made of tetrafluoroethylene resin is optimal in terms of liquid repellency, and the micropore diameter and porosity are determined by the sensitivity and durability of the porous tube itself. , (from j to micropore diameter of about 0.2 to about 1.0 μm1 opening rate of about 2
Something between 0 and about 80 is good. Among them, the copying hole diameter is approximately 0.4
Particularly preferred are those having a porosity of about 45 to 60 mm/~0.6 μm.

As the carrier gas, an inert gas such as nitrogen or air can be selected depending on the characteristics of the detector (5). Detector (5)
is a commercially available gas analyzer or gas detector that can measure volatile components in carrier gas stably, quickly, and accurately, such as a hydrogen flame ionization detector or a thermal conductivity detector. Choose from a wide range of price/infrared detectors, metal oxide film semiconductor detectors, catalytic combustion detectors, etc.
It can be selected based on accuracy etc. Among them, hydrogen flame ion ratio detectors are most popular in terms of accuracy and stability, metal oxide film V-conductor type detectors, and catalytic combustion type detectors are most popular in terms of cost and ease of use. The gear A rear gas supply section (2) must be able to stably supply and supply the carrier gas to the porous tube at a constant flow rate. Good results can be obtained by using a combination of constant flow valves, constant pressure valves, etc. used in gas chromatographs.

As described above, by using the method and device for measuring components in a liquid according to the present invention, it has become possible to measure sugars and salts extremely easily and quickly, which conventionally required many procedures and long periods of time for measurement and analysis. Ta.

In particular, the use of this measurement method and device has a great effect when the measurement of vaporizable components (e.g. ethanol) in a liquid is required at the same time, or when the conventional tube method is used to measure vaporizable components in a liquid. This function comes into play when a new measurement of sugar or salt concentration is required after a single measurement of ingredients has already been carried out. In these cases, it is possible to easily and quickly measure the concentration of vaporizable components in the liquid by simply adding some additional equipment or procedures to the measuring device using the tube method, which has been used for measuring the concentration of vaporized components in the liquid. Continuously determines the concentration of sugars or salts in the liquid.

Next, the present invention will be explained with reference to Examples.

Example 1 The concentration of each of the following four non-volatile substances in an aqueous solution was varied, and the concentration of the volatile component in the aqueous solution was measured using the tube method while keeping the concentration of the volatile component constant. The relationship between sensitivity to As the components to be measured, non-vaporizable substances such as arculose, common salt, sodium glutamate, and molasses were used. The molasses was used to supply sugar syrup for the cultivation of baker's yeast, and the Bertrand's molasses was 33 mm wide. Prepare aqueous solutions containing various concentrations of each of the above components, use ethanol as the volatile component,
The ethanol was added and mixed so that the concentration of ethanol increased by a constant concentration of 1 volume relative to the total amount of the aqueous solution.

The temperature of each solution was maintained at a constant value of 20'C, and the total constant sensitivity to ethanol was calculated by determining the measured' and P output values for the ethanol concentration in the solution using the tube method.

The equipment used to measure vaporizable components in liquid by the tube method is as follows.

The porous tube is made of porous tetrafluoroethylene resin, has a micropore diameter of approximately 0.45 μm, a porosity of approximately 55, and an inner diameter of 3.0 m.
A tube with an outer diameter of 4.0 mm and a length of about 10 cm was used. A hydrogen flame ionization detection IB was used as a detector, nitrogen gas was used as a carrier gas, and the flow rate of the carrier gas passing through the porous tube was maintained at about 40 tel/min. The carrier gas flow control section of the gas chromatograph was used as the carrier gas supply section. The carrier gas supply and discharge conduit is a stainless steel pipe (inner diameter 2.0 mm, outer diameter 8.0 mm).
Ortrm), and the discharge conduit was controlled at 950'C by a tape heater and a controller.

FIG. 2 shows the relationship between the concentration of the non-vaporizable substance, which is the component to be measured, in the solution obtained by the above operations, and the ethanol concentration.

Figure 2 shows the change when the concentration of non-vaporizable substances is 0, that is, when the solution components are only water and ethanol, and the measurement sensitivity to ethanol is 1.0, and the four types of components are mixed and dissolved in the solution. The measurement sensitivity for ethanol is shown as a relationship between the concentration of the non-vaporizable substance.

Example 2 An unknown amount of glucose was mixed and dissolved in water, and ethanol was added so that the ethanol concentration relative to the total solution increased by 1 volume to prepare a liquid to be measured.

The measurement sensitivity for the ethanol concentration output in the liquid to be measured was determined under the same conditions as those used to determine the relationship between the glucose concentration and ethanol measurement sensitivity in Example IK. Example 1 is a device for determining vaporizable components in a liquid using the tube method.
The same one used in was used.

The measurement results show that the measurement sensitivity for the ethanol concentration output is 1.
．． It was 11. When the glucose concentration was determined from the relationship curve between the glucose concentration determined in Example 1 and the measurement sensitivity to the ethanol concentration, the range was 10. Quantitatively dilute the sample solution, perform a color reaction using glucose oxidase,
The absorbance at 500 nm was measured, and the amount of glucose a in the test solution was determined from a previously prepared calibration curve of absorbance and glucose concentration, which was 10.5 qb, and the two measured values were in good agreement.

[Brief explanation of drawings]

FIG. 1 is an explanatory layout diagram showing the configuration of a measuring device according to the present invention. Figure 2 shows salt, glutamate sorter, molasses, which are non-volatile substances dissolved in water, respectively.
2 is a graph showing the relationship between each concentration of glycose and the sensitivity ratio of the ethanol concentration measurement output using the tube method (ratio to the sensitivity when the concentration of the non-vaporizable substance is O). ■... Porous tube, 2... Carrier gas supply section, 3... Carrier gas supply conduit, 4... Carrier gas discharge conduit, 5... Detector, 6... Heating device ,7...
・Measurement liquid, ll...vaporizable component supply value + & s
12... Measurement liquid stock solution tank, 13... Measurement liquid stock solution, 14... Measurement liquid transfer pump, 16... Measurement container, 17... Temperature controller, 1
8...Discharge valve, 19...Waste liquid tank, 20...
・Liquid temperature detection end, 21... Stirring mixer, 22...
Discharge line, 23... Arithmetic unit, 24... Storage device, 25... Temperature converter, 26... Display unit,
27...Output section.

Claims (9)

[Claims] (1) Measure the vapor pressure of the vaporizable component in a solution containing substantially one type of vaporizable component, a solution that does not dissolve the substance or a mixture thereof, and a solution in which various known amounts are dissolved; The relationship between the concentration of the non-gaseous substance or its mixture and the vapor pressure of the vaporizable component is determined in advance, and based on this, the measured value of the vapor pressure of the vaporizable component in the liquid to be measured is determined. A method for measuring concentration in a liquid, comprising measuring the concentration of the non-aerobic substance or a mixture thereof in a liquid to be measured. (2) The method for measuring the vapor pressure of volatile components in a solution is
Carrier gas is supplied to a porous tube with liquid repellency and continuous micropores that is immersed in the liquid to be measured, and the gas components of the carrier gas containing volatile component vapors that have diffused into the carrier gas through the tube wall are detected. The measuring method according to claim 1, which is a method using a tube-type measuring method that is guided into a container. (3) The tube-type measurement method is a method for measuring the concentration of vaporizable components in a liquid using a tube made of porous tetrafluoroethylene resin having liquid repellency and continuous micropores. Measurement method. (4) The measuring method according to claim 1, wherein the volatile component is ethanol or other alcohol. (5) The measuring method according to claim 1, wherein the liquid to be measured is a culture liquid of microorganisms. (6) The measuring method according to claim 1, wherein the liquid to be measured is an alcoholic beverage or soy sauce. (7) The non-vaporizable substance or mixture thereof is sucrose. The measuring method according to claim 1, wherein the measuring method is molasses, glucose or other saccharides. (8) Claim 1 in which the non-vaporizable substance or mixture thereof is common salt, sodium glutamate, or other salts.
Measurement method described in section. (9) A porous tube 1 having liquid repellency and continuous micropores, a carrier gas supply section 2 for supplying carrier gas to the tube via a carrier gas supply conduit 3, and a carrier gas discharge conduit to the tube. a detector 5 for detecting the concentration of aerosols in the carrier gas that has passed through the carrier gas; a measurement container 16 that accommodates the porous tube and the liquid to be measured 7; a device 11 for supplying an amount of vaporizable component, a mixing device 21 for uniformly mixing the vaporizable component into the liquid to be measured, and a method for measuring the vaporizable component for the concentration of the non-vaporizable substance or its mixture. The sensitivity corresponding to the concentration of the vaporizable component in the liquid to be measured is determined from the detector 5 (1'), and the sensitivity corresponding to the concentration of the vaporizable component in the liquid to be measured is determined from An in-liquid concentration measuring device consisting of a calculation section 23 that calculates the concentration of a substance or a mixture thereof, and a display section that displays the calculated value and/or an output section 27 that outputs the calculated value. The measuring device according to claim 9, which is a porous tetrafluoroethylene resin. (1) Claim 9, wherein the measuring container is equipped with a temperature regulator and a temperature detector for the liquid to be measured. The measuring device according to claim 9. u3 The measuring device according to claim 9, wherein the carrier gas discharge conduit is provided with a heating device. The measuring device according to claim 9, which is a calculation section having a compensation calculation function.