JPH04223266A - Trihalomethane analyzer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separation section of a trihalomethane analyzer, and more particularly to the structure of a separation section with excellent reliability.

0002

[Prior Art] In 1972, Rook of the Netherlands reported that a considerable concentration of organic chlorine compounds existed downstream of the Rhine River, and that trihalomethanes such as chloroform accounted for a large proportion of these organic chlorine compounds. It was done. Furthermore, a study found that there was a significant difference in cancer incidence between people who drank tap water containing trihalomethanes and those who did not drink tap water in the New Orleans region of the lower Mississippi River. , trihalomethanes in tap water attracted attention.

[0003] Subsequently, many studies have revealed that trihalomethanes are produced due to organic compounds in water and chlorine used to ensure epidemiological safety.

[0004] Under these circumstances, in Japan, 198
In March 2017, the Ministry of Health and Welfare decided to set the control target value for the concentration of trihalomethanes in tap water at 0.10 mg/l.

[0005] In order to solve this problem of trihalomethane and provide safe water to people, it is important to develop a water treatment technology that does not produce trihalomethane, and it is also necessary to develop a technology that accurately and quickly analyzes trihalomethane. become.

[0006] As shown in Table 1, trihalomethane is a substance with a relatively low boiling point, so it easily volatilizes from sample water. In particular, chloroform, which is contained more than other trihalomethane substances in tap water, has the lowest boiling point at 61.2°C. Also, unlike other components, its concentration is low at the ppb level. Therefore, in order to analyze these accurately, extreme care must be taken in the operations from water collection to storage to analysis.

[0007]

[Table 1]

[0008] Known methods for analyzing trihalomethanes include separating and concentrating trihalomethanes using a headspace method, solvent extraction method, purge trap method, etc., and then quantifying them using gas chromatography with ECD; After that, a method of quantifying using fluorescence method is known (Japanese Patent Application Laid-Open No. 2-14
5961, JP-A-1-268745).

However, among these methods, the former method has the problem that the operation is complicated and requires skill, and the measurement takes a long time. Furthermore, regarding the latter, when applied to samples from some regions where organic substance pollution has progressed, the values may be higher than those measured by gas chromatography, which is the official method.

When chlorine is added to water containing organic matter,
For example, it is known that a halogenation reaction of a precursor such as a humic substance occurs, and then a hydrolysis reaction gradually proceeds to slowly produce trihalomethane. This hydrolysis reaction occurs rapidly when the pH is high or the liquid temperature is high. In the trihalomethane analyzer, residual chlorine is reduced and removed using a sodium sulfite solution to prevent the halogenation reaction, which is the production reaction of trihalomethane, and the subsequent hydrolysis reaction, etc., from occurring when heated in the separation section 2. However, some organic substances undergo a halogenation reaction and have already completed the transition from precursors to intermediates before being introduced into the analyzer, and these organic substances may be affected by heating operations or pH conditions in the separation section. , a hydrolysis reaction is carried out to produce new trihalomethanes without the presence of residual chlorine. This is one of the reasons why the measured values are larger than those measured by gas chromatography.

Furthermore, in the separation section, a portion of the sample solution passes through the microporous tube and is injected into the carrier solution, and the intermediate that has completed the halogenation reaction in the sample solution is removed in the separation section, etc. Due to the heating operation and the high pH of the carrier solution, a hydrolysis reaction occurs to generate new trihalomethane in the carrier solution. This is the second factor that gives the measured values larger than those measured by gas chromatography.

FIG. 5 is a block diagram showing a conventional trihalomethane analyzer. This trihalomethane analyzer is an analyzer that eliminates discrepancies with the official method using the above-mentioned gas chromatograph and provides measurement values that are in good agreement with the official method. This analyzer includes a carrier liquid feeding section 2, a sample solution supplying section 1,
It consists of a separation section 3, a reaction section 4, a defoaming section 5, and a detection section 6.

The sample solution supply section 1 mixes a sample containing trihalomethane with an acidic reducing agent solution to prepare a sample solution, and supplies the sample solution to the separation section 3 . The carrier liquid sending section 2 mixes the nicotinic acid amide solution with the sodium hydroxide solution and sends the mixture to the separating section 3 . FIG. 6 is a sectional view showing the separation section 3. As shown in FIG. The separation section 3 consists of two isolated microporous fluororesin tubes in a closed space, and a carrier and a sample solution are flowed into each of the microporous fluororesin tubes. Separation section 3 is heated to a predetermined temperature. Trihalomethane in the sample solution evaporates through the micropores of the microporous tube and is dissolved and transferred into the carrier. The trihalomethane in the carrier then reacts with nicotinic acid amide in the reaction section 4 to produce a fluorescent substance. The reaction section is also heated. The carrier is defoamed in the defoaming section 5, and the fluorescence intensity is measured in the detection section 6. The detection section 6 is controlled by a control section, and a calculation section, a display section, and a recording section are attached to the fluorescence detector. The closed space of the separation section is
Filled with air purified by activated carbon. Once the analysis is complete, the separation section is evacuated and filled with fresh air. Purified water is sent to the separation section to clean the inside of the microporous fluororesin tube. Analysis of purified water gives a zero score. Analyzes using standard solutions are performed in the same way.

In the above-mentioned analyzer, the temperature of the separation section is set at a temperature at which the intermediate, which has undergone the halogenation reaction, does not undergo a hydrolysis reaction. Since the acidic reducing agent solution makes the pH of the sample solution acidic, hydrolysis of the intermediate is prevented.

[0015]

[Problems to be Solved by the Invention] However, in the above-mentioned trihalomethane analyzer, in order to increase the sensitivity of the analyzer, it is necessary to increase the diameter of the microporous fluororesin tube through which the sample solution flows to about 3 mm in outer diameter. There is. The length cannot be increased due to pressure loss, difficulty in assembling, etc. Figure 7 shows the characteristics when the diameter is increased.
is shown.

FIG. 7 is a graph showing the change over time in the relative fluorescence intensity of a chloroform standard solution (100 ppb) of a conventional analyzer. It can be seen that the intensity, that is, the sensitivity decreases with time. In this way, the conventional trihalomethane analyzer described above can match the official method as far as accuracy is concerned, but it is said that it lacks reliability when trying to increase sensitivity by increasing the diameter of the microporous fluororesin tube. There was a problem.

As a result of examining the cause of the decrease in sensitivity, it was found that the microporous resin tube tends to shrink when its outer diameter is large, and as a result, the number of micropores through which trihalomethane evaporates decreases over time.

The present invention has been made in view of the above points, and its purpose is to prevent the micropores in which trihalomethane evaporates from changing over time in the sample solution flow path in the separation section.
Our objective is to provide a highly reliable trihalomethane analyzer.

[0019]

[Means for Solving the Problems] According to the present invention, the above-mentioned object includes a carrier liquid feeding section, a sample solution supplying section, a separating section, a defoaming section, and a detection section, and a carrier feeding section. The liquid part supplies a carrier mixture of a sodium hydroxide solution and a nicotinic acid amide solution to the separation part, and the sample solution supply part supplies a sample solution, which is a mixture of a sample containing trihalomethane and an acidic reducing agent solution, to the separation part. , the separation section is provided with a channel through which the carrier flows and a channel through which the sample solution flows, separated from each other, and at least a portion of these channels is formed of microporous resin; The part of the microporous resin is in a closed space, and the part of the microporous resin in the flow path through which the sample solution flows has a flat membrane shape, and the reaction part is in a closed space, and the part of the microporous resin in the channel through which the sample solution flows is a flat membrane. The migrated trihalomethane is reacted with nicotinic acid amide, the defoaming section removes air bubbles in the carrier generated in the reaction section via a microporous tube, and the detection section measures the fluorescence intensity of the reaction product in the reaction section. This is achieved by assuming that

[0020]

[Operation] The microporous resin flat film formed by stretching under high temperature conditions (
(30 to 70°C), no thermal contraction occurs and no change in micropores occurs.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing a separation section of a trihalomethane analyzer according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a separation section of a trihalomethane analyzer according to a different embodiment of the invention. The trihalomethane analyzer of this invention differs from the conventional trihalomethane analyzer shown in FIG. 5 only in the separation section.

In the carrier liquid feeding section 2, a nicotinic acid amide solution with a concentration of 30 to 40% and a sodium hydroxide solution with a concentration of 0.2 to 0.4M are pumped through peristaltic pumps 9A and 2, respectively.
9B at 0.5 ml/min. is sent to the mixing coil 10 at a flow rate of .

[0023] The nicotinamide solution and the sodium hydroxide solution are well mixed by the mixing coil 10,
It serves as a carrier and is sent into a flow path formed by a microporous fluororesin tube 11 in the separation section or into a flow path having a microporous fluororesin flat membrane 12 as a part. On the other hand, a sample containing trihalomethane was prepared using an acidic reducing agent solution (1% hydrazine sulfate) while the operation of the air pump 17 was stopped.
and 4m by peristaltic pumps 13A and 13B, respectively.
l/min. , 0.5ml/min. It is sent to the mixing coil 14 at a flow rate of , and mixed well. The sample solution generated by this mixing is the microporous fluororesin flat membrane 15,
16 in a part of the flow path. Separation part is 40
It is maintained at a predetermined temperature within the range of ~100°C, and the trihalomethane in the sample solution is gasified and evaporated from the microporous fluororesin flat membrane, and is then formed in the other microporous fluororesin tube 11 within the separation section. The carrier permeates into a channel having a flat microporous fluororesin membrane 12 in a part thereof and is redissolved in the carrier flowing therein.

The carrier is sent to the reaction section 4, where trihalomethane and alkaline nicotinic acid amide react to produce a fluorescent condensation substance. The reaction section 4 is maintained at a predetermined temperature within the range of 70 to 105°C. Next, the carrier moves to the defoaming section 5.
sent to. The defoaming section 5 is made of microporous fluororesin tube (
The water pressure resistance is preferably about 2.0 kg/cm2), the micropore diameter is 1 to 3 μm, and the length is 10 to 30 cm. After defoaming, the carrier is sent to the detection section 6 and the fluorescence intensity is measured.

After the measurement is completed, the air pump 17 is activated to replace the air in the separation section with clean air free of trihalomethane, and the valve 18 is switched to send purified water to clean the inside of the separation section and wait until the next measurement. .

FIG. 3 is a diagram showing the calibration relationship when using chloroform in the trihalomethane analyzer according to the embodiment of the present invention. FIG. 4 is a diagram showing the stability over time of the relative fluorescence intensity of a chloroform standard solution of the analyzer according to the embodiment of the present invention. It can be seen that no change occurs over time even after 30 days or more.

Table 2 is a list showing the measurement results of tap water using the analyzer according to the embodiment of the present invention.

[0028]

[Table 2]

The values measured by the analyzer of the present invention and the values measured by the official gas chromatograph method show good agreement.

[0030]

Effects of the Invention According to the present invention, the carrier liquid feeding section has a carrier liquid feeding section, a sample solution supplying section, a separation section, a defoaming section, and a detection section, and the carrier liquid feeding section has a carrier liquid feeding section that contains a sodium hydroxide solution and a nicotine solution. Supply the carrier mixed with the acid amide solution to the separation section,
The sample solution supply section supplies a sample solution in which a sample containing trihalomethane is mixed with a solution of an acidic reducing agent to the separation section, and the separation section is configured such that the channel through which the carrier flows and the channel through which the sample solution flows are isolated from each other. At least a portion of these flow channels is formed of microporous resin, and in this case, the microporous resin portion of the flow channel is in a closed space and the microporous resin portion of the flow channel through which the sample solution flows. The porous resin part has a flat membrane shape, and the reaction part allows the carrier to flow and reacts trihalomethane transferred from the sample solution with nicotinic acid amide, and the defoaming part removes air bubbles in the carrier generated in the reaction part. is removed through a microporous tube, and the detection section measures the fluorescence intensity of the reaction product in the reaction section.

[0031] Due to the mechanical stability of the microporous resin flat membrane produced by stretching at high temperatures, the micropores do not change over time under the temperature conditions of the separation section, and a highly reliable trihalomethane analyzer can be obtained. .

[Brief explanation of the drawing]

[Fig. 1] A cross-sectional view showing a separation section of a trihalomethane analyzer according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a separation section of a trihalomethane analyzer according to a different embodiment of the present invention.

FIG. 3 is a diagram showing the calibration relationship when using chloroform in the trihalomethane analyzer according to the embodiment of the present invention.

[Figure 4
] Diagram showing the stability over time of the relative fluorescence intensity of the chloroform standard solution of the trihalomethane analyzer according to the embodiment of the present invention.

[Figure 5] Configuration diagram showing a conventional trihalomethane analyzer

[Figure 6] Cross-sectional view showing the separation section of a conventional trihalomethane analyzer

[Figure 7] Chloroform standard solution (100
ppb) Diagram showing relative fluorescence intensity changes over time

[Explanation of symbols]

1 Sample solution supply section 2 Carrier liquid feeding section 3 Separation section 4 Reaction section 5 Defoaming section 6 Detection section 9A Pump 9B Pump 10 Mixing coil 11 Microporous fluororesin tube 12 Microporous fluororesin flat membrane 13A Pump 13B Pump 15 Microporous fluororesin flat membrane 16 Microporous fluororesin flat membrane 17 Air pump 18 Valve

Claims (5)

[Claims] Claim 1: A carrier liquid feeding section, a sample solution supplying section, a separating section, a defoaming section, and a detection section, the carrier liquid feeding section supplying a sodium hydroxide solution and a nicotinic acid amide solution. The mixed carrier is supplied to the separation section, and the sample solution supply section supplies a sample solution in which a sample containing trihalomethane is mixed with an acidic reducing agent solution to the separation section. Flow channels are provided to be separated from each other, and at least a portion of these channels is formed of microporous resin, and in this case, the microporous resin portion of the flow channel is in a closed space. At the same time, the microporous resin part of the channel through which the sample solution flows has a flat membrane shape;
The reaction section allows the carrier to flow and causes the trihalomethane transferred from the sample solution to react with nicotinic acid amide, the defoaming section removes air bubbles in the carrier generated in the reaction section through a microporous tube, and the detection section A trihalomethane analyzer, characterized in that it measures the fluorescence intensity of reaction products in a reaction section. 2. The trihalomethane analyzer according to claim 1, wherein the acidic reducing agent is hydrazine sulfate. 3. The trihalomethane analyzer according to claim 1, wherein the separation section is heated to a predetermined temperature within the range of 30 to 70°C. 4. The trihalomethane analyzer according to claim 1, wherein the flow path through which the carrier flows is a tube. 5. The trihalomethane analyzer according to claim 1, wherein the microporous resin is a microporous fluororesin.