JP2018119885A - Total phosphorus automatic measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a total phosphorus automatic measurement device capable of suppressing an increase in an exchange frequency of a reagent and improving operability.SOLUTION: A total phosphorus automatic measurement device 100 repeatedly measures a phosphate ion concentration by a molybdenum blue absorptiometry method, and includes: a measurement cell 1; first supply means 2 for supplying a water sample to the measurement cell 1 at a predetermined cycle; second supply means 3 for supplying a L-ascorbic acid solution to the measurement cell 1 at the predetermined cycle: third supply means for supplying a molybdenum acid solution to the cell 1 at the predetermined cycle; a measurement part 52 for measuring an optical density after completion of a color reaction in the mixed solution of the water sample, the L-ascorbic acid solution, and the molybdenum acid solution supplied to the measurement cell 1; and discharge means 6 for discharging the mixed solution inside the measurement cell 1 after measurement of the optical density. The second supply means 3 stores the L-ascorbic acid solution in a storage container 31 made of a brown glass.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a total phosphorus automatic measuring apparatus for measuring a phosphate ion concentration in a sample water by molybdenum blue absorptiometry.

  Since phosphorus is a factor that promotes eutrophication in lakes and the like, it is necessary to measure the phosphorus concentration in water. As a method for measuring phosphorus concentration, molybdenum blue absorptiometry is known. Molybdenum blue absorptiometry produces molybdenum blue by reducing a compound of phosphate ion and molybdate in water with L-ascorbic acid, and measuring the absorbance of this molybdenum blue gives phosphate ion. It is a method of quantification.

  For example, an all-phosphorus automatic measuring apparatus that automatically measures a phosphorus concentration periodically using a molybdenum blue absorptiometry is known (see, for example, Patent Document 1). Such an apparatus is used for the purpose of regularly monitoring the phosphorus concentration of lakes and marshes, natural water of rivers, and wastewater from factories and the like over a long period of time.

JP, 2015-127675, A

  Since the L-ascorbic acid solution used as a reagent for molybdenum blue absorptiometry is easily deteriorated, long-term storage is difficult. Therefore, it has been necessary to replace the L-ascorbic acid solution in the conventional all-phosphorus automatic measuring apparatus in anticipation of the reagent deterioration time.

  By the way, the all-phosphorus automatic measuring device is often installed in an environment with a large temperature change because of its use. In such an environment, since the deterioration of the L-ascorbic acid solution is promoted, the frequency of reagent replacement increases. This is a major problem in improving the operability of the all phosphorus automatic measuring apparatus.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an all-phosphorus automatic measurement apparatus that can suppress an increase in reagent replacement frequency and improve operability.

In order to solve the above-mentioned problems, the characteristic configuration of the total phosphorus automatic measuring device according to the present invention is as follows:
A total phosphorus automatic measuring device that repeatedly measures phosphate ion concentration in sample water by molybdenum blue absorptiometry,
A measuring cell;
First supply means for supplying a predetermined amount of sample water to the measurement cell at a predetermined cycle;
Second supply means for supplying an L-ascorbic acid solution to the measurement cell at the predetermined cycle;
Third supply means for supplying the molybdic acid solution to the measurement cell at the predetermined cycle;
A measurement unit for measuring the absorbance of the mixed solution after completion of the color reaction in the mixed solution of the sample water, the L-ascorbic acid solution, and the molybdic acid solution supplied to the measurement cell;
Discharging means for discharging the mixed liquid in the measurement cell after measuring the absorbance;
With
The second supply means has a brown glass storage container that stores an L-ascorbic acid solution, and a pump unit that sucks a predetermined amount of the L-ascorbic acid solution from the storage container and supplies the L-ascorbic acid solution to the measurement cell. It is in.

  In conventional measuring devices that continuously and automatically measure the phosphorus concentration in the liquid, unless the reagent used is corrosive and chemical resistance is required for its storage, it is inexpensive to store the reagent in the device. A resin container is used. For the L-ascorbic acid solution that can be handled without any special care, a resin container such as a brown polyethylene tank has been used for storage in a conventional measuring apparatus.

  According to the all phosphorus automatic measuring device of this structure, since the storage container is a product made from brown glass, permeation | transmission of the air in a container wall surface can be suppressed. Therefore, compared with the conventional measuring apparatus using a resin container, the deterioration of the L-ascorbic acid solution stored in the apparatus does not easily progress, and the compound (color inhibiting compound) that inhibits the color reaction over time. Increase can be suppressed. This makes it possible to extend the exchange period of the L-ascorbic acid solution and improve the operability of the all-phosphorus automatic measuring device.

In the total phosphorus automatic measuring apparatus according to the present invention,
The storage container has a lid,
The pump unit includes the first pump for sucking the L-ascorbic acid solution from the storage container, the metering pipe for metering the L-ascorbic acid solution sucked by the first pump, and the metering by the operation of the first pump. A second pump that sucks the L-ascorbic acid solution filled in the pipe and discharges it to the measurement cell;
The lid part is connected to the outflow hole into which the suction pipe of the first pump is inserted and the metering pipe, and when the suction amount of the first pump exceeds the volume of the metering pipe, It is preferable that the storage container includes a reflux hole for refluxing the L-ascorbic acid solution and an intake hole that suppresses fluctuations in the internal pressure of the storage container.

  According to the total phosphorus automatic measuring device of this configuration, since the L-ascorbic acid solution excessively sucked up by the first pump during measurement is returned to the storage container, the L-ascorbic acid solution is measured and measured with a simple configuration. The L-ascorbic acid solution stored in the storage container can be effectively used without waste while being supplied to the cell. For this reason, it is not necessary to add an L-ascorbic acid solution frequently to a storage container, and an all-phosphorus automatic measuring apparatus can be operated efficiently.

  In addition, air flows into the storage container from the intake hole during the operation of the second pump. However, since the storage container is made of brown glass, the permeation of air from the container wall surface into the container is suppressed, and L that contacts the wall surface -The ascorbic acid solution is not oxidized by the air passing through the wall surface. For this reason, the oxidation of the L-ascorbic acid solution is limited to that via the liquid surface, and the rate of increase of the color-inhibiting compound in the L-ascorbic acid solution over time can be reduced.

In the total phosphorus automatic measuring apparatus according to the present invention,
It is preferable to be installed in an environment of 5 ° C or higher and 40 ° C or lower.

  According to the all phosphorus automatic measuring apparatus of this structure, it can be used in an appropriate use environment also in the use which examines the natural water of a river, the drainage from a factory, etc.

In the total phosphorus automatic measuring apparatus according to the present invention,
The first supply means acquires the test target water containing phosphorus from the water source at the predetermined cycle, and adds the oxidizing agent to the acquired test target water to generate the sample water containing phosphate ions. preferable.

  According to the total phosphorus automatic measuring apparatus of this structure, it can repeat from acquisition of test object water to drainage periodically, and can measure the total phosphorus amount contained in a liquid continuously. Therefore, it is possible to constantly monitor the water quality with high operability by using natural water of a river or waste water from a factory as water to be inspected.

FIG. 1 is a block diagram of a total phosphorus automatic measuring apparatus according to the present invention. FIG. 2 is an explanatory view schematically showing an L-ascorbic acid solution supply unit. FIG. 3 is a flowchart of the total phosphorus continuous measurement method. FIG. 4 is a graph showing (a) a change with time in the absorbance ratio in the example, and (b) a graph showing change in the absorbance ratio with time in the comparative example.

  First, the background of the present invention will be described. In the operation of the total phosphorus automatic measuring device, the concentration of the L-ascorbic acid solution decreases with time, so that periodic reagent replacement is necessary. Generally, in an all-phosphorus automatic measuring apparatus, the L-ascorbic acid concentration of a reagent to be newly replaced is often adjusted to about 15 g / L.

  Here, a comparative experiment using a molybdenum blue absorptiometry between a case where a reagent whose L-ascorbic acid concentration was adjusted to 15 g / L was used and a case where a reagent whose L-ascorbic acid concentration was adjusted to 8 g / L was used. As a result, no significant difference was observed in the absorbance between the two. That is, even a reagent having an L-ascorbic acid concentration adjusted to 8 g / L had reducibility necessary for the color reaction. From this, even if the L-ascorbic acid concentration is reduced to about 8 g / L due to the deterioration of the reagent during operation of the total phosphorus automatic measuring apparatus, it is predicted that there is sufficient practicality.

  However, when the inventors examined the operation results of the total phosphorus automatic measuring device in detail, the concentration of the L-ascorbic acid solution may decrease from 15 g / L to 8 g / L in the installation environment of the total phosphorus automatic measuring device. It was found that reagent replacement was required at intervals shorter than the expected period. In addition, when the absorbance was measured while bubbling the L-ascorbic acid solution to promote oxidation, it was found that the solution concentration dropped from 15 g / L by about 20%, and the measurement was affected when the solution concentration reached about 12 g / L. confirmed. From these facts, the reason why the color reaction does not sufficiently progress during the operation of the total phosphorus automatic measuring apparatus is not simply due to the decrease in the concentration of the L-ascorbic acid solution, but the chemical reaction such as the oxidation reaction of L-ascorbic acid. It is presumed that the compound produced by the above is related to the inhibition of the color reaction.

  Based on this new knowledge, the inventors of the L-ascorbic acid solution stored in the apparatus over time of a compound that is considered to inhibit the color reaction (hereinafter, “color-inhibiting compound”). We examined an automatic measuring device for total phosphorus that can suppress the increase.

  Hereinafter, an embodiment relating to an automatic measurement apparatus for total phosphorus of the present invention will be described with reference to FIGS. However, the present invention is not intended to be limited to the configurations described in the embodiments and drawings described below.

<All phosphorus automatic measuring device>
The total phosphorus automatic measuring apparatus 100 according to the present invention is used to repeatedly measure the phosphorus concentration in water to be inspected such as industrial waste water at a predetermined cycle (for example, about every hour). Therefore, the total phosphorus automatic measuring apparatus 100 is preferably installed and operated in an environment of 5 ° C. or higher and 40 ° C. or lower. FIG. 1 is a block diagram of a total phosphorus automatic measuring apparatus 100. The total phosphorus automatic measuring apparatus 100 includes a measurement cell 1, a sample water supply unit 2, an L-ascorbic acid solution supply unit 3, a molybdic acid solution supply unit 4, an absorptiometer 5, and a discharge unit 6, and further has an arbitrary configuration. As shown, a cell cleaning unit 7 is provided. The operations of the sample water supply unit 2, the L-ascorbic acid solution supply unit 3, the molybdic acid solution supply unit 4, the absorptiometer 5, the discharge unit 6, and the cell cleaning unit 7 are controlled by the control unit 8.

The measurement cell 1 is a container formed of a transparent material such as quartz glass.
The sample water supply unit 2 includes a sample water generation unit 21, a sample water meter 22, a first valve 23, and a second valve 24, and a pipe is connected to the measurement cell 1. The sample water generating unit 21 takes water to be inspected from a factory drain pipe or the like as a water source, adds an oxidizing agent such as a potassium peroxodisulfate solution to the water to be inspected, and heats it to decompose all phosphorus. Sample water as phosphate ions is generated. The sample water meter 22 is composed of a syringe or the like, and weighs an amount (for example, 5 ml) of sample water used for one measurement by the molybdenum blue absorptiometry from the sample water generated in the sample water generator 21. The first valve 23 introduces sample water from the sample water generator 21 to the sample water meter 22, and the second valve 24 introduces the measured sample water from the sample water meter 22 to the measurement cell 1. Each component is controlled by the control unit 8 and the sample water supply unit 2 functions as a first supply unit of the present invention by supplying an appropriate amount of sample water to the measurement cell 1 every hour.

  The L-ascorbic acid solution supply unit 3 includes a storage container 31 and a pump unit 32, and a pipe is connected to the measurement cell 1. The details of the L-ascorbic acid solution supply unit 3 will be described with reference to FIG. The container main body 33 and the lid portion 34 constitute a storage container 31. The first pump 35, the second pump 36, the suction pipe 37, the metering pipe 38, and the supply pipe 39 constitute the pump unit 32.

  The all-phosphorus automatic measuring apparatus 100 is characterized in that a brown glass bottle is used as the container body 33. The capacity of the container body 33 is set to, for example, about 1 L (liter), and the L-ascorbic acid solution L is accommodated in the container body 33. In the operation of the total phosphorus automatic measuring apparatus 100, the amount of the L-ascorbic acid solution L is adjusted so that the air layer V is secured in the container main body 33 immediately after the reagent replacement. The amount of the L-ascorbic acid solution L in the container main body 33 at the time immediately after the reagent replacement is, for example, 800 ml (milliliter). With this amount, the L-ascorbic acid solution L remains sufficiently in the container body 33 until immediately before the next reagent replacement, and the concentration of the color-inhibiting compound due to evaporation of the L-ascorbic acid solution L during operation is reduced. .

  The lid portion 34 has, for example, a spiral groove inside the cylindrical portion, and is configured to be screwed into a spiral groove provided outside the open end portion of the container body 33. Moreover, it is preferable that the lid portion 34 is provided with packing on a surface in contact with the opening end surface of the container main body 33 and is in close contact with the opening end surface of the container main body 33. The top plate of the lid portion 34 is provided with three through holes, an outflow hole 34a, a reflux hole 34b, and an intake hole 34c. A suction pipe 37 is inserted into the outflow hole 34a, and a measuring pipe 38 is inserted into the reflux hole 34b. The end of the suction pipe 37 inserted into the container main body 33 from the outflow hole 34 a is immersed in the liquid of the L-ascorbic acid solution L so that the tip is located near the inner bottom surface of the container main body 33. ing. The other end of the suction pipe 37 is connected to the suction port of the first pump 35.

  The first pump 35 is a tube pump, and one end of the metering pipe 38 is connected to the discharge port of the first pump 35. The other end of the metering pipe 38 has a reflux hole 34b so that the tip 38b stays in the air layer V at the time immediately after the reagent replacement, that is, in a state where the liquid level of the L-ascorbic acid solution L is at the highest level. Is inserted into the container body 33. The volume from the branch 38a of the measuring pipe 38 to the tip 38b inserted into the container body 33 (hereinafter referred to as “measurement volume”) depends on the amount of sample water introduced into the measurement cell 1 in the molybdenum blue absorptiometry. It is configured to match the amount of L-ascorbic acid solution required. For example, when the sample water introduced into the measurement cell 1 is 5 ml, the measurement volume is adjusted to be about 0.35 ml.

  The second pump 36 is a tube pump, and a pipe branched from the measuring pipe 38 is connected to the suction port, and one end of the supply pipe 39 is connected to the discharge port. The other end of the supply pipe 39 is connected to the measurement cell 1 (not shown).

  By controlling the first pump 35 and the second pump 36 by the control unit 8, the L-ascorbic acid solution supply unit 3 measures the L-ascorbic acid solution every time sample water is injected into the measurement cell 1. 1 is supplied. Thereby, L-ascorbic acid solution supply part 3 functions as the 2nd supply means of the present invention.

  Specifically, in the supply operation of the L-ascorbic acid solution to the measurement cell 1, first, the L-ascorbic acid solution is sucked up from the container body 33 by the drive of the first pump 35 and discharged to the measuring pipe 38. . The excessively sucked L-ascorbic acid solution flows back to the container main body 33 through the metering pipe 38, so that excessive air flow in and out of the container main body 33 through the intake hole 34c when the first pump 35 is driven. Does not occur. After the L-ascorbic acid solution is filled in the entire metering pipe 38 by driving for a certain time, the first pump 35 is stopped. At that time, the L-ascorbic acid solution filled in the metering pipe 38 does not leak and remains in the metering pipe 38 as it is. The amount of the L-ascorbic acid solution held in the flow path from the branch 38 a to the tip 38 b inserted into the container main body 33 in the measurement pipe 38 is defined by the measurement volume.

  When the second pump 36 is driven after the first pump 35 is stopped, the L-ascorbic acid solution held between the branch 38 a and the tip 38 b inserted into the container body 33 is sucked up and supplied to the supply pipe 9. Discharged. While the second pump 36 is being driven, air flows into the storage container 33 from the outside of the container through the intake hole 34c, whereby the internal pressure fluctuation of the container body 33 is suppressed. The L-ascorbic acid solution staying in the suction-side and discharge-side piping of the second pump 36 is eliminated by driving for a fixed time, and the second pump 36 is stopped after the entire suction-side and discharge-side piping is filled with air. To do. As a result, all of the L-ascorbic acid solution for the metered volume held in the metering pipe 38 is introduced into the measurement cell 1 through the supply pipe 39.

  With the above supply operation, the accurately weighed L-ascorbic acid solution can be supplied to the measurement cell 1.

  Returning to FIG. 1, the description of the all phosphorus automatic measuring apparatus 100 will be continued. The molybdic acid solution supply unit 4 includes a storage container 41 and a pump unit 42, and a discharge side pipe of the pump unit 42 is connected to the measurement cell 1. Similarly to the L-ascorbic acid solution supply unit 3, the molybdic acid solution supply unit 4 controls the pump unit 42 by the control unit 8, and each time sample water is injected into the measurement cell 1, the molybdic acid solution is supplied to the measurement cell 1. To supply. Thereby, the molybdic acid solution supply part 4 functions as the third supply means of the present invention. The detailed configuration of the molybdic acid solution supply unit 4 is the same as that of the L-ascorbic acid solution supply unit 3 described with reference to FIG. 2, and detailed description thereof is omitted.

  The absorptiometer 5 includes a light source 51 and a measurement unit 52. As the light source 51, for example, a lamp, an LED, or the like that emits light having a wavelength used in molybdenum blue absorptiometry (for example, light having a peak near 880 nm) can be used. The light source 51 and the measurement unit 52 are arranged so that light emitted from the light source 51 passes through the measurement cell 1 and enters the light receiving window of the measurement unit 52. After the sample water, the L-ascorbic acid solution, and the molybdic acid solution are introduced into the measurement cell 1, the light source 51 and the measurement unit 52 have sufficient time (for example, the color reaction in the mixed solution to be completed (for example, 10 minutes to 15 minutes), the control unit 8 controls to emit light and measure absorbance.

  The discharge unit 6 is a valve that operates according to the control of the control unit 8 and functions as a discharge unit of the present invention. Specifically, the discharge unit 6 is controlled to be closed until the sample water, the L-ascorbic acid solution, and the molybdic acid solution are introduced into the measurement cell 1 and the absorbance measurement by the absorptiometer 5 is completed, It is controlled to open after the absorbance measurement is completed. Thereby, the liquid mixture in the measurement cell 1 can be quickly discharged after measuring the absorbance.

  The cell cleaning unit 7 is a valve that operates according to the control of the control unit 8. The cell washing unit 7 is connected to the washing water supply port, and introduces washing water into the measurement cell 1 after the mixed liquid is discharged, thereby washing the measurement cell 1. As the washing water, pure water purified from clean water using an ion exchange resin or the like can be used. Thereby, the light absorbency measurement with respect to the following sample water can be implemented, without leaving the molybdenum blue produced by the color reaction in the measurement cell 1. FIG.

  The control unit 8 is a computer having a CPU, a memory, a storage, and the like. The control unit 8 reads out the program recorded in the memory and executes the all-phosphorus automatic measurement process, thereby controlling each of the above-described components and executing the absorbance measurement, and the measured absorbance. A function of calculating the phosphorus concentration in the sample water and a function of recording the calculated phosphorus concentration in the storage are realized. In addition, the control part 8 can also control the start and stop of the total phosphorus automatic measuring apparatus 100 by remote operation by receiving the input of a signal via an electric wire, a communication line, etc.

  The details of the all phosphorus automatic measurement process executed by the control unit 8 will be described. FIG. 3 is a flowchart showing a control procedure by the control unit 8. In the all-phosphorus automatic measurement process, the control unit 8 sets a periodic timer (step S1), controls the intake of water to be inspected and the generation of sample water (step S2), introduces sample water and reagents into the measurement cell 1. Control (step S3), color reaction (step S4), absorbance measurement control (step S5), calculation of phosphorus concentration from absorbance measurement value (step S6), recording of calculated value in storage (step S7), measurement cell 1 Each procedure of the liquid mixture discharge control (step S8) and each part cleaning control (step S9) is sequentially executed. Thereafter, the control unit 8 waits for the time-out of the periodic timer (step S10), and when a time-out notification event occurs (step S10: Yes), the procedure from step S1 to step S9 is repeated to repeat the periodic phosphorus concentration. Enables automatic measurement.

  The setting of the periodic timer in step S1 specifically sets a predetermined waiting time (for example, about 1 hour) in a general timer function that generates a timeout notification event when a set time has elapsed. Control. Further, the control in step S <b> 2 is control for the sample water generating unit 21. The control in step S3 includes control for the sample water supply unit 2 for introducing the sample water into the measurement cell 1, and control for the L-ascorbic acid solution supply unit 3 and the molybdate solution supply unit 4 for introducing the reagent into the measurement cell 1. It is. In step S4, a timer function or the like is performed for a sufficient time (for example, 10 to 15 minutes) for the color reaction to be completed with the sample water introduced into the measurement cell 1 in step S3 and the mixed solution of the reagents. This is a process of using and waiting. In step S9, in addition to the control on the cell cleaning unit 7, the piping of the total phosphorus automatic measuring apparatus 100 and the function of cleaning the components connected to the piping are controlled.

  Each control in step S2, step S3, step S5, step S8, and step S9 includes a sample water supply unit 2, an L-ascorbic acid solution supply unit 3, a molybdic acid solution supply unit 4, an absorptiometer 5, and a discharge unit 6. Since the details have already been described in the description of the cell cleaning unit 7, the description thereof is omitted here.

  With the above configuration, the all-phosphorus automatic measuring apparatus 100 can automatically measure the phosphorus concentration in water to be inspected such as industrial wastewater repeatedly at a predetermined cycle (for example, about every hour).

  Note that the present invention uses a brown glass bottle as the container body 33 of the storage container 31, and in the total phosphorus automatic measuring apparatus 100 storing the L-ascorbic acid solution, the water to be inspected is processed by the processing procedure of the flowchart shown in FIG. It is also possible to use a total phosphorus automatic measurement method in which the phosphorus concentration in is continuously measured. Or it is good also as a computer program containing the program code which operates all the phosphorus automatic measurement apparatuses 100 in the process sequence of the flowchart shown in FIG. Further, the present invention provides a computer-readable recording medium such as a flexible disk, a hard disk, a CD-ROM, an MO, a DVD, a DVD-ROM, a DVD-RAM, a BD (Blu-ray (registered trademark) Disc). ), Recorded in a semiconductor memory or the like.

  Next, although the total phosphorus automatic measuring apparatus according to the present invention will be described in more detail based on specific examples, the present invention is not limited to these.

[Test 1]
(Examples 1 and 2)
L-ascorbic acid was adjusted to a concentration of 15 g / L using ion-exchanged water and stored in a storage container. A brown glass bottle was used for the container body of the storage container, and the container was stored in an environment of 45 ° C. for 20 days. Every few days, an L-ascorbic acid solution was collected from the storage container, and the absorbance of a phosphorus sample with a known concentration was measured by molybdenum blue absorptiometry. The measurement was carried out twice under the same conditions (Examples 1 and 2). The measurement results were converted to an absorbance ratio (%) relative to the absorbance when using the standard reagent, using a 15 g / L L-ascorbic acid solution newly prepared at the time of measurement as the standard reagent. The absorbance ratio is calculated according to the following formula.
Absorbance ratio (%) = absorbance when using reagent collected from storage container / absorbance when using standard reagent × 100

(Comparative Examples 1 and 2)
A brown polyethylene tank was used as the container body of the storage container, and the absorbance was measured twice under the same conditions (Comparative Examples 1 and 2). Other configurations were the same as those in Examples 1 and 2.

(Comparative Example 3)
As the container body of the storage container, a milky white polyethylene tank was used, and the absorbance was measured once (Comparative Example 3). Other configurations were the same as those in Examples 1 and 2.

  As a result of the test, the L-ascorbic acid solution using the bottle made of brown glass for the container body of Examples 1 and 2 does not show a large change in the absorbance ratio throughout the test period, and can be used as a reagent for a long period of time. Showed that. From this, it was recognized that the increase in the color-inhibiting compound over time in the L-ascorbic acid solution can be suppressed by using a brown glass bottle for the container body in the total phosphorus automatic measuring device.

  On the other hand, the L-ascorbic acid solution of Comparative Example 1 using a brown polyethylene tank for the container body had a significantly reduced absorbance ratio after 17 days from the start of the test. After 20 days from the start of the test, the absorbance ratio was 93.5%. In the L-ascorbic acid solution of Comparative Example 2 using a brown polyethylene tank for the container body, the absorbance ratio decreased more significantly after 17 days from the start of the test. After 20 days from the start of the test, the absorbance ratio was 91.5% or less. The L-ascorbic acid solution of Comparative Example 3 using a milky white polyethylene tank for the container body had an absorbance ratio of 91.0% after 20 days from the start of the test. Therefore, in any of Comparative Examples 1 to 3, the effect of suppressing the increase in the coloration inhibiting compound over time was not sufficient. In addition, since there is no significant difference in the absorbance ratio after 20 days from the start of the test between Comparative Examples 1 and 2 and Comparative Example 3, simply changing the color of the polyethylene tank increases the usable period of the stored reagent. It was confirmed that the extension effect was small.

[Test 2]
(Examples 3, 4, and 5)
L-ascorbic acid was adjusted to a concentration of 15 g / L using ion-exchanged water and stored in a storage container. A brown glass bottle was used for the container body of the storage container, and the lid of the total phosphorus automatic measuring apparatus according to the present invention was attached. The storage container changed the ambient temperature to 32 ° C. and 40 ° C. every 12 hours, imitating the usage environment of the all-phosphorus automatic measuring apparatus in which the ambient temperature varied daily. In addition, the storage container was ventilated by a pump through the intake holes at regular intervals. Every few days, an L-ascorbic acid solution was collected from the storage container, and the absorbance of a phosphorus sample having a known concentration was measured by molybdenum blue absorptiometry. The measurement was carried out three times under the same conditions (Examples 3, 4, and 5). The measurement result was converted into an absorbance ratio according to Test 1.

(Comparative Examples 4, 5, 6)
A milk white polyethylene tank was used as the container body of the storage container, and the absorbance was measured three times under the same conditions (Comparative Examples 4, 5, 6). Other configurations were the same as those in Examples 3 to 5.

  4A is a graph showing the change with time in the absorbance ratio in Examples 3 to 5, and FIG. 4B is a graph showing the change with time in the absorbance ratio in Comparative Examples 4 to 6. FIG.

  As a result of the test, in Examples 3 and 5 in which a brown glass bottle was used for the container body, the absorbance ratio greatly decreased to 99% or less after 28 days from the start of the test. In Example 4, the absorbance ratio greatly decreased to 99% or less after 37 days from the start of the test. It was shown that the L-ascorbic acid solution stored for about 4 weeks can be used as a reagent by using a brown glass bottle for the container body. From this, in Examples 3 to 5, it was confirmed that an increase in the color-inhibiting compound over time in the L-ascorbic acid solution could be suppressed. In the total phosphorus automatic measuring apparatus according to the present invention using a brown glass bottle as a storage container, it is considered that reagent replacement is required in about 4 weeks.

  On the other hand, in Comparative Example 4 using a milky white polyethylene tank for the container body, the absorbance ratio showed a remarkable decreasing tendency after 8 days from the start of the test, and the absorbance ratio became 99% or less after 9 days. In Comparative Example 5, after 11 days from the start of the test, the absorbance ratio showed a remarkable decreasing tendency, and after 16 days, the absorbance ratio became 99% or less. In Comparative Example 6, the absorbance ratio greatly decreased after 14 days from the start of the test to 99% or less. In a conventional all-phosphorus automatic measuring apparatus using a milky white polyethylene tank as a storage container, it is considered that reagent replacement is required in about two weeks.

[Discussion]
As described above, in the total phosphorus automatic measuring apparatus 100 of the present invention, the container body 33 made of brown glass is provided as the storage container 31, so that the color-inhibiting compound ages over time in the L-ascorbic acid solution stored in the apparatus. It is thought that the increase can be suppressed. Therefore, it becomes possible to extend the exchange period of the L-ascorbic acid solution, and to improve operability.

<Another embodiment>
Although the present invention has been described based on the above embodiment, it is needless to say that the present invention is not limited to the above embodiment. For example, as another embodiment, the following modifications can be implemented.

(Modification 1)
In the above embodiment, when the second pump 36 is driven, the air flows into the container body 33 through the intake hole 34c. However, when the second pump 36 is driven, the inert gas flows into the container body 33. You may comprise. In such a configuration, for example, a soft bag in which a resin film having gas barrier properties and flexibility is formed in a bag shape is filled with an inert gas, and the soft bag is connected to the intake hole 34c directly or via a pipe. Can be realized. Instead of the soft bag filled with the inert gas, an inert gas supply means such as a cylinder for supplying the inert gas may be connected to the intake hole 34c. Alternatively, as another example, the storage container 31 can be stored in a casing filled with an inert gas. The entire L-ascorbic acid solution supply unit 42 may be stored in a casing filled with an inert gas.

  If the inert gas flows into the container main body 33 through the intake holes 34c, the oxidation of the L-ascorbic acid solution stored in the container main body 33 can be further suppressed. The increase can be further suppressed. Thereby, the further operativity improvement of the all-phosphorus automatic measuring apparatus 100 can be aimed at.

As the inert gas, nitrogen gas (N ₂ ), carbon dioxide gas (CO ₂ ), argon gas (Ar), helium gas (He), or the like can be used. In particular, it is preferable to use nitrogen gas from the viewpoint of easy availability and handling.

  In addition, the inert gas may not only passively flow into the container main body 33 when the second pump 36 is driven, but may also actively flow into the container main body 33. For example, in a configuration in which a soft bag filled with an inert gas is connected to the intake hole 34c, the inert gas can be caused to flow into the container body 33 by applying pressure to the soft bag. In particular, this operation is performed before connecting the pipe to at least one of the outflow hole 34a and the reflux hole 34b at the time of reagent replacement, whereby the inside of the container body 33 can be purged with an inert gas. By the inert gas purge in the container main body 33, the contact of air with the liquid surface of the L-ascorbic acid solution in the container main body 33 can be suppressed. Therefore, the oxidation of L-ascorbic acid can be suppressed, and the increase with time of the color-inhibiting compound in the L-ascorbic acid solution can be suppressed. This makes it possible to extend the exchange period of the L-ascorbic acid solution and improve the operability of the all-phosphorus automatic measuring device.

(Modification 2)
The storage container 31 may be provided with a deoxygenation means. The deoxygenating means can be realized, for example, by attaching a deoxidizing agent to the lower surface of the top plate of the lid portion 34. With such a configuration, the oxygen scavenger absorbs oxygen in the air layer V, so that contact of oxygen with the liquid surface of the L-ascorbic acid solution in the container body 33 can be suppressed. Therefore, the oxidation of L-ascorbic acid can be suppressed, and the increase with time of the color-inhibiting compound in the L-ascorbic acid solution can be suppressed. This makes it possible to extend the exchange period of the L-ascorbic acid solution and improve the operability of the all-phosphorus automatic measuring device.

  The automatic total phosphorus measuring device of the present invention can be used for the purpose of automatically measuring the phosphorus concentration continuously, using natural water such as rivers and lakes, factory effluent and the like as inspection targets.

DESCRIPTION OF SYMBOLS 1 Measurement cell 2 Sample water supply part 3 L-ascorbic acid solution supply part 4 Molybdate solution supply part 5 Absorbance meter 6 Discharge part 31 Reservoir container 32 Pump part 33 Container main body 34 Lid part 34a Outflow hole 34b Reflux hole 34c Intake hole 35 1st pump 36 2nd pump 37 Suction piping 38 Metering piping 51 Light source 52 Measuring unit 100 Total phosphorus automatic measuring device

Claims (4)

A total phosphorus automatic measuring device that repeatedly measures phosphate ion concentration in sample water by molybdenum blue absorptiometry,
A measuring cell;
First supply means for supplying a predetermined amount of sample water to the measurement cell at a predetermined cycle;
Second supply means for supplying an L-ascorbic acid solution to the measurement cell at the predetermined cycle;
Third supply means for supplying the molybdic acid solution to the measurement cell at the predetermined cycle;
A measurement unit for measuring the absorbance of the mixed solution after completion of the color reaction in the mixed solution of the sample water, the L-ascorbic acid solution, and the molybdic acid solution supplied to the measurement cell;
Discharging means for discharging the mixed liquid in the measurement cell after measuring the absorbance;
With
The second supply means includes a brown glass storage container that stores an L-ascorbic acid solution, and a pump unit that sucks a predetermined amount of the L-ascorbic acid solution from the storage container and supplies the L-ascorbic acid solution to the measurement cell. Phosphorus automatic measuring device. The storage container has a lid,
The pump unit includes the first pump for sucking the L-ascorbic acid solution from the storage container, the metering pipe for metering the L-ascorbic acid solution sucked by the first pump, and the metering by the operation of the first pump. A second pump that sucks the L-ascorbic acid solution filled in the pipe and discharges it to the measurement cell;
The lid part is connected to the outflow hole into which the suction pipe of the first pump is inserted and the metering pipe, and when the suction amount of the first pump exceeds the volume of the metering pipe, The total phosphorus automatic measuring device according to claim 1, comprising a reflux hole for refluxing the L-ascorbic acid solution in the storage container, and an intake hole for suppressing fluctuations in internal pressure of the storage container.   The total phosphorus automatic measuring device according to claim 1 or 2, which is installed in an environment of 5 ° C or higher and 40 ° C or lower.   The said 1st supply means acquires the test object water containing phosphorus from a water source with the said predetermined period, adds an oxidizing agent to the acquired test object water, and produces | generates the said sample water containing a phosphate ion. The all-phosphorus automatic measuring apparatus as described in any one of 1-3.

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