JP2009014382A - Trihalomethane measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a trihalomethane measuring instrument that sufficiently mixes a fluorescent analyzing reagent and sodium hydroxide, and eliminates the irregularity of the sensor output of the detection part without extending a measuring time to enhance the sensitivity. <P>SOLUTION: The trihalomethane measuring instrument is equipped with a sample solution sending part 10 for sending out a sample solution containing trihalomethane, a carrier liquid sending part 20 for sending out a carrier liquid, a separation and dissolution part 30 for dissolving and transferring trihalomethane in the sample solution in the carrier liquid, a reaction part 40 for producing a fluorescent substance from trihalomethane and the fluorescence analyzing reagent, and the detection part 50 for measuring the fluorescence intensity of the fluorescent substance. The carrier liquid sending part 20 is equipped with a mixing tank 23 into which the fluorescence analyzing reagent and sodium hydroxide are introduced, an air pump 25 for depressurizing the mixing tank to introduce the two liquids into the mixing tank, air blowing-in piping 28 for blowing air into the mixing tank to mix two liquids to prepare the carrier liquid and a liquid sending pump 29 for sending the carrier liquid to the separation and dissolution part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a trihalomethane measuring apparatus for measuring the concentration of trihalomethane, which is a low melting point organic chlorine compound contained in water.

  As a trihalomethane measuring apparatus, as described in JP-A-2-145916, JP-A-3-218461, JP-A-4-158261, JP-A-6-160370, etc., a fluorescence analysis method is used. An apparatus for continuously analyzing trihalomethane in water with high accuracy has been developed and put into practical use. Examples of these conventional devices are shown in FIG.

  As shown in FIG. 5, in this apparatus, first, a sample water containing trihalomethane supplied from the branch pipe 11 and an acidic reducing agent solution supplied from the branch pipe 12 are mixed using a liquid feed pump 13. This is made into a solution and sent to the sample solution flow path 33 of the separation and dissolution unit 30 via the main pipe 14. In addition, the liquid analysis pump 63 is used to mix the trihalomethane fluorescence analysis reagent supplied from the branch pipe 61 and sodium hydroxide supplied from the branch pipe 62 to form a carrier liquid, which is separated and dissolved via the main pipe 65. To the carrier liquid channel 34 of the unit 30.

  In the separation and dissolution unit 30, the sample solution flowing through the sample solution flow path 33 is heated to about 70 ° C. by the heater 35 to separate and remove the trihalomethane gas from the sample solution. This trihalomethane gas passes through the micropores of the gas separation microporous flat membrane 31 and the gas separation microporous tube 32 from the sample solution flow path 33 and dissolves in the carrier liquid flowing in the carrier liquid flow path 34.

Next, the carrier liquid in which the trihalomethane is dissolved is introduced into the reaction unit 40 and heated to about 90 ° C., whereby the trihalomethane in the carrier liquid reacts with the fluorescence analysis reagent to generate a fluorescent substance. The carrier liquid containing the fluorescent substance is introduced into the detection unit 50, and the fluorescence intensity of the fluorescent substance in the carrier liquid is measured, thereby quantifying trihalomethane.
Japanese Patent Laid-Open No. 4-158261 JP-A-6-160370

  The trihalomethane measuring apparatus using such a fluorescence analysis method has the following two problems. First, as a first problem, a carrier liquid in which a fluorescent analysis reagent for trihalomethane supplied from the pipe 61 and sodium hydroxide supplied from the pipe 62 is mixed with the carrier of the separation and dissolution unit 30 via the pipe 60. Although supplied to the liquid flow path 34, since the viscosity of these two liquids is extremely different, there is a problem that mixing is insufficient.

  The branch tubes 61 and 62 for the fluorescence analysis reagent and sodium hydroxide are usually laminar in both the two liquids in order to allow the liquid to flow continuously at a low flow rate of 0.75 ml / min. . In general, mixing of liquids in a laminar flow region is difficult due to the diffusion of both. Therefore, the fluorescence analysis reagent and sodium hydroxide merge immediately after the liquid feed pump 63, but the mixing is insufficient. When the trihalomethane gas is dissolved in the carrier liquid flow path 34 of the separation and dissolution unit 30 in such a state that the carrier liquid is not sufficiently mixed, the trihalomethane, the fluorescence analysis reagent, There is a problem that this reaction becomes insufficient, and the measured values of fluorescence intensity vary greatly. FIG. 6 shows a sensor output result of the detector 50 when the sample water having a trihalomethane concentration of 5 μg / l is measured by the measuring apparatus having the configuration shown in FIG.

  As countermeasures against this problem, coil-type and T-type in-line mixers that can be stirred and mixed even in a laminar flow are commercially available, but they are expensive and have problems such as a large apparatus size, as well as reagents and solvents used in this apparatus. Since the amount of liquid is very small, such as several tens of ml in one measurement, and the flow rate is as slow as 1.6 cm / second, even if a commercially available inline mixer 64 is used as shown in FIG. Is inadequate.

  The second problem is that the longer the contact time and the reaction time between the carrier liquid and the trihalomethane gas (that is, the slower the carrier liquid flow rate in the separation and dissolution unit 30), the higher the sensitivity of the sensor of the detection unit 50. New knowledge was obtained. However, if the flow rate of the liquid feeding pump 63 is lowered to further reduce the flow rate of the carrier liquid from the current level, the mixing of the fluorescence analysis reagent and sodium hydroxide becomes further insufficient, as shown in FIG. Since the liquid feeding pump 63 performs the process from the supply of the fluorescence analysis reagent and sodium hydroxide to the separation / dissolution unit 30 to the feeding of the carrier liquid to the detection unit 50, the measurement time per measurement becomes long. There is.

  Therefore, in view of the above problems, the present invention can sufficiently mix the fluorescence analysis reagent for trihalomethane and sodium hydroxide, and can reduce variations in sensor output and sensitivity of the detection unit without increasing the measurement time. An object of the present invention is to provide a trihalomethane measuring apparatus that can be improved.

  In order to achieve the above object, a trihalomethane measuring apparatus according to the present invention includes a sample feeding section for feeding a sample solution in which sample water containing trihalomethane and an acidic reducing agent solution are mixed, a fluorescence analysis reagent for trihalomethane, and hydroxylation. A carrier liquid feeding part for feeding out a carrier liquid mixed with sodium; a separation and dissolution part for feeding and transferring the trihalomethane in the sample solution into the carrier liquid, wherein the sample solution and the carrier liquid are supplied; and A carrier liquid that has been dissolved and transferred is supplied, a reaction unit that generates a fluorescent substance from trihalomethane and a fluorescence analysis reagent in the carrier liquid, and a carrier liquid containing the fluorescent substance are supplied, and the fluorescence of the fluorescent substance in the carrier liquid is supplied. A trihalomethane measuring device comprising a detector for measuring trihalomethane by measuring intensity. The carrier liquid feeding section has a mixing tank into which the fluorescence analysis reagent and the sodium hydroxide are introduced, and a negative pressure in the mixing tank so that the fluorescence analysis reagent and the water are contained in the mixing tank. An air pump for introducing sodium oxide, an air blowing pipe for stirring and mixing air into the fluorescence analysis reagent and the sodium hydroxide introduced into the mixing tank to form the carrier liquid, and the mixing tank And a liquid feed pump for feeding the inner carrier liquid to the separation and dissolution section.

  In this way, the fluorescence analysis reagent and sodium hydroxide are temporarily stored in the mixing tank by the air pump, and the fluorescence analysis reagent and water having extremely different viscosities are obtained by blowing air from the air blowing pipe. Sodium oxide can be thoroughly stirred and mixed in-line. Therefore, even if the concentration of trihalomethane in the sample water is low, the reaction efficiency between the trihalomethane and the fluorescence analysis reagent in the reaction section is improved, so that variation in the sensor output of the fluorescence intensity in the detection section can be reduced.

  Also, by lowering the flow rate of the liquid delivery pump and lowering the flow rate of the carrier liquid, the contact time and reaction time between the trihalomethane gas and the carrier liquid become longer, so the sensitivity of the fluorescence intensity sensor output at the detection unit is improved. be able to. At that time, due to the decrease in the flow rate of the carrier liquid, the time for the carrier liquid to move from the separation and dissolution part to the detection part becomes longer. However, since the reaction efficiency is improved by mixing and stirring and the flow rate is lowered, the time until the reaction is saturated is shortened. As a result, the increase in time due to the decrease in the flow velocity is offset, and it is possible to avoid an increase in measurement time.

  The carrier liquid feeding section preferably further comprises a pressure gauge for measuring the pressure in the mixing tank, and a control means for controlling the operation of the air pump based on the pressure value measured by the pressure gauge. Thus, by controlling the operation of the air pump based on the value measured by the pressure gauge, the pressure in the mixing tank can be pumped up into the mixing tank in a short time with the fluorescence analysis reagent and sodium hydroxide. Can be within the negative pressure range.

  As described above, according to the present invention, the fluorescence analysis reagent for trihalomethane and sodium hydroxide can be sufficiently mixed, and the sensor output variation and sensitivity of the detection unit can be improved without lengthening the measurement time. It is possible to provide a trihalomethane measuring apparatus capable of

  Hereinafter, an embodiment of a trihalomethane measuring apparatus according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing an embodiment of a trihalomethane measuring apparatus according to the present invention.

  As shown in FIG. 1, the trihalomethane measuring apparatus according to the present embodiment includes a sample feeding unit 10 that sends out a sample solution in which sample water containing trihalomethane and an acidic reducing agent solution are mixed, a fluorescence analysis reagent for trihalomethane, and hydroxylation. Carrier liquid feeding section 20 for feeding out a carrier liquid mixed with sodium, separation / dissolution section 30 for dissolving and transferring trihalomethane in the sample solution into the carrier liquid, and trihalomethane and fluorescence analysis in the carrier liquid in which this trihalomethane is dissolved and transferred The reaction unit 40 mainly generates a fluorescent substance from a reagent, and a detection unit 50 that quantifies trihalomethane by measuring the fluorescence intensity of a carrier liquid containing the fluorescent substance.

  The sample solution supply unit 10 includes a sample solution main pipe 14 connected to the sample solution flow path 33 of the separation and dissolution unit 30 and two branch pipes connected to the main pipe, that is, a branch pipe 11 for sample water containing trihalomethane. A branch pipe 12 for an acidic reducing agent solution is disposed. The two branch pipes 11 and 12 are provided with a liquid feed pump 13 for sending liquid to the main pipe side. Further, the two branch pipes 11 and 12 are provided with opening and closing solenoid valves, respectively.

  The carrier liquid feeding section 20 is provided with a branch pipe 21 for a fluorescent analysis reagent for trihalomethane, a branch pipe 22 for sodium hydroxide, and a sealed mixing tank 23 to which these branch pipes are connected. The mixing tank 23 is provided with a pipe 24 in which an air pump 25 for making the inside of the mixing tank 23 negative and a pressure gauge 16 for measuring the pressure in the mixing tank 23 are installed. Further, a carrier liquid main pipe 26 is disposed between the lower portion of the side surface of the mixing tank 23 and the carrier liquid flow path 34 of the separation and dissolution section 30. The main pipe 26 is provided with a liquid feed pump 29 for sending the liquid to the separation and dissolution unit side.

  Further, the mixing tank 23 is provided with a pipe 27 for opening the inside of the mixing tank 23 to the atmosphere, and an air blowing pipe 28 configured to blow out air from the bottom of the mixing tank 23. Yes. These pipes 27 and 28 and the above branch pipes 21 and 22 are respectively provided with opening and closing solenoid valves.

  The separation / dissolution part 30 has a cylindrical shape, and a gas permeable tube 32 parallel to the axial direction is provided inside the separation / dissolution part 30. A gas permeable flat membrane 31 is provided between the inner wall in the axial direction of the separation / dissolution part 30 and the gas permeable tube 32 in parallel with them. The inner wall of the separation and dissolution part 30 and the gas permeable flat membrane 31 constitute a closed space, and this space becomes the sample solution flow path 33. Further, the inner space of the gas permeable tube 32 becomes the carrier liquid flow path 34. The remaining space, that is, the space between the gas permeable tube 32 and the gas permeable flat membrane 31 and the inner wall of the separation / dissolution part 30 is a gas phase space.

  The separation and dissolution unit 30 is provided with a heater 35 for heating to a temperature at which trihalomethane in the sample solution flowing through the sample solution flow path 33 volatilizes. The gas phase space of the separation and dissolution unit 30 is provided with a cleaning air pipe 36 for supplying cleaning air into the gas phase space, and an exhaust pipe 38 for discharging the cleaned air. ing. The cleaning air pipe 36 is provided with an air pump 37 for sending air and an electromagnetic valve for opening and closing. The sample solution flow path 33 of the separation and dissolution unit 30 is provided with a drainage pipe 39 for discharging the sample solution from which trihalomethane has been separated and removed.

  Between the carrier liquid flow path 34 and the reaction part 40 of the separation / dissolution part 30, a pipe 41 for carrier liquid that connects them is disposed. The reaction unit 40 is provided with means (not shown) for heating to a temperature at which trihalomethane in the carrier liquid reacts with the fluorescence analysis reagent to produce a fluorescent substance. For example, piping for carrier liquid is heated with boiling water.

  Between the reaction part 40 and the detection part 50, the piping 51 for carrier liquid which connects these is arrange | positioned. The detector 50 is provided with means (not shown) for measuring the fluorescence intensity of the fluorescent substance in the carrier liquid and calculating the concentration of trihalomethane in the sample water from the measured value and a preset calibration curve. ing. The detection unit 50 is provided with a pipe 52 for discharging the carrier liquid after measurement. This pipe 52 joins the drainage pipe 39 of the separation and dissolution unit 30 and then goes to a waste liquid treatment facility (not shown). It is connected with.

  According to the above configuration, first, the electromagnetic valves of the branch pipe 21 for the reagent for fluorescence analysis, the branch pipe 22 for sodium hydroxide, the pipe 27 for opening to the atmosphere, and the pipe 28 for blowing air are closed. In addition, the operation of the air pump 25 is started with the liquid feed pump 29 stopped. Thereby, the pressure in the mixing tank 23 falls. The pressure is measured with a pressure gauge 16. When the pressure in the mixing tank 23 reaches a predetermined negative pressure, both the solenoid valves for the fluorescent analysis reagent branch pipe 21 and the sodium hydroxide branch pipe 22 are opened. As a result, the fluorescence analysis reagent and sodium hydroxide are pumped from the branch pipes 21 and 22 into the mixing tank 23.

  In addition, as a reagent for fluorescence analysis, it is preferable to use a nicotinamide solution, and the concentration is preferably 30 to 40%. As sodium hydroxide, a sodium hydroxide solution is preferably used, and its concentration is preferably 0.2 to 0.4M. The mixing ratio of these two liquids is preferably 50:50, for example.

  When a predetermined amount of the fluorescence analysis reagent and sodium hydroxide are pumped into the mixing tank 23, the solenoid valves of the branch pipes 21 and 22 are closed, and the air pump 25 is stopped. The amount of the fluorescence analysis reagent and sodium hydroxide to be pumped into the mixing tank 23 is an amount used in one measurement, and is preferably set to 40 ml in total, for example. The pressure in the mixing tank 23 is preferably in a range where the time required for pumping is within 1 minute, for example, about 10 seconds, and is preferably in the range of 5 to 10 kPa, for example. The air pump 25 can be operated and stopped by a control means (not shown) such as a sequencer based on the value measured by the pressure gauge 16 so that the pressure in the mixing tank 23 falls within a predetermined range. .

  When pumping of the fluorescence analysis reagent and sodium hydroxide into the mixing tank 23 is completed, the solenoid valve of the air blowing pipe 28 is opened, and air is blown into the fluorescence analysis reagent and sodium hydroxide. Thereby, the reagent for fluorescence analysis and sodium hydroxide are sufficiently stirred and mixed to form a carrier liquid.

  Next, the solenoid valve of the air blowing pipe 28 is closed, the pipe 27 for opening to the atmosphere is opened, and the operation of the liquid feeding pump 29 is started, so that the entire amount of the carrier liquid in the mixing tank 23 is used for the carrier liquid. The liquid is fed to the carrier liquid flow path 34 of the separation and dissolution unit 30 through the main pipe 26. When the feeding of the carrier liquid is finished and the inside of the mixing tank 23 is emptied, the electromagnetic valve of the pipe 27 for opening to the atmosphere is closed, and the liquid feeding pump 29 is stopped. In preparation for the next measurement, the above-described series of operations starting from the start of the operation of the air pump 25 is performed again, and the sufficiently mixed carrier liquid is temporarily stored in the mixing tank 23. The opening and closing of the solenoid valves of the branch pipes 21 and 22, the solenoid valve of the air blowing pipe 28, and the solenoid valve of the pipe 27 for opening to the atmosphere can also be controlled by the control means.

  When the operation of the liquid feeding pump 29 is started, the solenoid valves of the branch pipes 11 and 12 for the sample water and the acidic reducing agent solution are opened, and the operation of the liquid feeding pump 13 is started. As a result, the sample water and the acidic reducing agent solution supplied from the branch pipes 11 and 12 are mixed in the main pipe 14 to obtain a sample solution, which is supplied to the sample solution flow path 33 of the separation and dissolution unit 30. As the acidic reducing agent solution, a hydrazine sulfate solution is preferable, and the concentration thereof may be about 1%, for example. Further, the mixing ratio of the sample water and the acidic reducing agent solution is set to a volume ratio of 89:11 by setting the flow rate of the sample water to 4 ml / min and the flow rate of the acidic reducing agent solution to 0.5 ml / min, for example. be able to.

  Then, by heating the sample solution supplied to the sample solution flow path 33 of the separation and dissolution unit 30 to, for example, 70 ° C. with the heater 35, the trihalomethane in the sample solution becomes gaseous, and the holes of the microporous flat membrane 31 for gas separation are formed. Pass through and separate from the sample solution in the sample solution channel 33. The trihalomethane gas further passes through the holes of the gas separation microporous tube 32 and dissolves in the carrier liquid flowing through the carrier liquid flow path 34.

  The carrier liquid in which the trihalomethane is dissolved is introduced into the reaction unit 40 and heated to about 90 ° C., whereby the trihalomethane in the carrier liquid reacts with the fluorescence analysis reagent to produce a fluorescent substance (the fluorescence analysis reagent is nicotinic acid). In the case of amides, the Fujiwara reaction occurs). The carrier liquid containing the fluorescent substance is introduced into the detection unit 50, the fluorescence intensity of the fluorescent substance in the carrier liquid is measured, and the concentration of trihalomethane in the sample water is determined from the measured value and the calibration curve obtained from the standard solution in advance. Can be requested.

  The carrier liquid after the fluorescence intensity is measured by the detection unit 50 is discharged from the drainage pipe 52. The sample solution from which trihalomethane has been separated and removed by the sample solution flow path 33 of the separation and dissolution unit 30 is discharged from the drainage pipe 39. At the end of the measurement, the electromagnetic valve of the cleaning air pipe 36 is opened and the air pump 37 is operated to introduce air into the gas phase space of the separation and dissolution unit 30 and discharge it from the exhaust pipe 38. The remaining trihalomethane gas can be purged to clean the gas phase space of the separation and dissolution unit 30.

  In this way, the reagent for fluorescence analysis and sodium hydroxide are temporarily stored in the mixing tank 32, and mixed in-line by in-line by blowing air, so that they can be sufficiently mixed even if the viscosity is extremely different. Even if the concentration of trihalomethane in the sample water is low, the reaction efficiency between the trihalomethane and the fluorescence analysis reagent in the reaction unit 40 is improved, and thus the variation in the sensor output of the fluorescence intensity in the detection unit 50 is reduced, and the signal The noise-to-noise ratio (S / N) is improved.

  FIG. 2 shows a sensor output result of the detector 50 when sample water having a trihalomethane concentration of 5 μg / l is measured by the measuring apparatus having the configuration shown in FIG. It can be seen that the variation in sensor output is greatly reduced and the S / N is improved as compared with FIG. 6 in which the stirring and mixing by air blowing is not performed.

  Further, the flow rate of the liquid pump 29 is greatly reduced, and the flow rate of the carrier liquid flowing through the separation and dissolution unit 30, the reaction unit 40, and the detection unit 50 is decreased, so that the reaction between the trihalomethane and the fluorescence analysis reagent in the reaction unit 40 occurs. The efficiency is improved, and therefore the sensitivity of the sensor output of the fluorescence intensity in the detection unit 50 can be greatly improved.

  FIG. 3 shows the case where the carrier liquid flow rate is current (1.6 cm / sec) and stirring and mixing with air is not performed, and when the flow rate is 1/3 of that and mixing and mixing with air is performed. The relationship between a density | concentration and the sensor output of fluorescence intensity is shown. As shown in FIG. 3, if the flow rate is reduced to one third of the current level, it can be expected that the sensitivity is improved more than twice the current level.

  When the flow rate of the carrier liquid is lowered, the time for the carrier liquid to move from the separation and dissolution unit 30 to the detection unit 50 becomes longer, but the reaction is saturated because the reaction efficiency of trihalomethane and the reagent for fluorescence analysis is increased. The time to do is shortened. Therefore, even if the flow rate of the carrier liquid is lowered from the current level, it is possible to avoid an increase in measurement time.

  FIG. 4 shows changes in the sensor output of the fluorescence intensity from the start of measurement to the end of measurement when the flow rate of the carrier liquid is lowered to 1/3 of the current (1.6 cm / sec). For comparison, the current sensor output change is indicated by a broken line. As shown in FIG. 4, the current time is about three-thirds from point A at which the supply of the sample solution and carrier liquid starts to point B at which the carrier liquid reaches the detector and the sensor output starts increasing. It takes. However, since the reaction efficiency is improved, the time from point B to point C where the reaction is saturated and the sensor output is stabilized can be shortened from about 30 minutes to about 20 minutes. The time from point C to point D at which the purging of the trihalomethane gas is started by the air pump takes about 15 minutes as in the current case. Further, it takes about three-thirds of the current time from the point D to the point E where the carrier liquid when the purge is completed reaches the detector and the sensor output is completely lowered. Therefore, the measurement time per measurement from the point A at the start of measurement to the point F at the end of measurement is maintained at about 60 minutes (including the margin) as with the current flow rate even if the flow rate is 1/3 of the current flow rate. can do.

It is a schematic diagram which shows one Embodiment of the trihalomethane measuring apparatus which concerns on this invention. It is a graph which shows the result of the sensor output of the detection part in the structure shown in FIG. It is a graph which shows the relationship between the trihalomethane density | concentration and sensor output when the flow velocity of carrier liquid is lowered to 1/3. It is a graph which shows the change of the sensor output with respect to the measurement time at the time of reducing the flow velocity of carrier liquid to 1/3 of the present. It is a schematic diagram which shows an example of the conventional trihalomethane measuring apparatus. It is a graph which shows the result of the sensor output of the detection part in the structure shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sample liquid feeding part 11 Branch pipe for sample water 12 Branch pipe for acidic reducing agent solution 13, 29 Liquid feeding pump 16 Pressure gauge 20 Carrier liquid feeding part 21 Branch pipe for fluorescence analysis reagent 22 Branch pipe for sodium hydroxide 23 Mixing Tank 25, 37 Air pump 27 Air release pipe 28 Air blowing pipe 30 Separation and dissolution part 31 Gas permeable flat membrane 32 Gas permeable tube 33 Sample solution flow path 34 Carrier liquid flow path 35 Heater 36 Cleaning air pipe 38 Exhaust piping 39, 52 Drainage piping 40 Reaction unit 50 Detection unit

Claims (2)

A sample feeding section for feeding a sample solution obtained by mixing a sample water containing trihalomethane and an acidic reducing agent solution;
A carrier liquid feeding part for sending out a carrier liquid in which a fluorescent analysis reagent for trihalomethane and sodium hydroxide are mixed;
The sample solution and the carrier liquid are supplied, and a separation / dissolution part for dissolving and transferring the trihalomethane in the sample solution into the carrier liquid;
A carrier liquid in which the trihalomethane is dissolved and transferred is supplied, and a reaction unit that generates a fluorescent substance from the trihalomethane and the fluorescence analysis reagent in the carrier liquid,
A trihalomethane measurement device comprising: a carrier liquid containing the fluorescent substance; and a detector for quantifying trihalomethane by measuring the fluorescence intensity of the fluorescent substance in the carrier liquid,
The carrier liquid feeding part is
A mixing tank into which the fluorescence analysis reagent and the sodium hydroxide are introduced;
An air pump that introduces the fluorescence analysis reagent and the sodium hydroxide into the mixing tank by setting the inside of the mixing tank to a negative pressure,
An air blowing pipe that blows and mixes air into the fluorescence analysis reagent introduced into the mixing tank and the sodium hydroxide to produce the carrier liquid; and
A trihalomethane measurement apparatus comprising: a liquid feed pump for sending the carrier liquid in the mixing tank to the separation and dissolution unit.   The carrier liquid feeding section further includes a pressure gauge for measuring the pressure in the mixing tank, and a control means for controlling the operation of the air pump based on the pressure value measured by the pressure gauge. The trihalomethane measuring apparatus according to claim 1.

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