JP2019100804A - Concentration measurement method, concentration management method, concentration measurement device, and concentration management device - Google Patents

Abstract

To improve accuracy of measurement when measuring concentration of nitrate nitrogen in specimen including nitrite nitrogen and nitrate nitrogen by use of a reduction column.SOLUTION: A concentration measurement method comprises : reacting a specimen including nitrite nitrogen and nitrate nitrogen with color reagent reacting only nitrite nitrogen thereby detecting first absorbance (step S13, S14, S17); reacting the specimen with the color reagent after passing through reduction column thereby detecting second absorbance (step S15-S17); correcting the first absorbance by use of absorbance change rate η that is a ratio of absorbance of nitrite nitrogen standard solution obtained by passing through the reduction column to absorbance obtained by not passing through the reduction column, and measuring concentration of nitrate nitrogen in the specimen before passing through the reduction column based on difference between the corrected first absorbance and the corrected second absorbance, and predetected characteristic information (step S18).SELECTED DRAWING: Figure 7

Description

  The present invention relates to a concentration measurement method, a concentration management method, a concentration measurement device, and a concentration management device.

The concentration of dissolved inorganic nitrogen contained in wastewater from marine rivers and factories is measured as one of the indicators for grasping the status of environmental pollution and aquaculture. Dissolved inorganic nitrogen includes, for example, nitrite nitrogen and nitrate nitrogen.
As a method of measuring the concentration of nitrite nitrogen and nitrate nitrogen, for example, a method of measuring the total concentration of nitrate nitrogen and nitrite nitrogen in seawater by measuring the ultraviolet absorption spectrum by absorption spectrophotometry is proposed. (See, for example, Patent Document 1).

  In addition, in the second part of JIS K 0170-2, “Nitrite nitrogen and nitrate nitrogen”, as a water quality test method by flow analysis, nitrite nitrogen and nitrate nitrogen are analyzed by spectrophotometric flow analysis A method for quantification using a method has been defined (see, for example, Non-Patent Document 1). In this water quality test method, after nitrate nitrogen is reduced to nitrite nitrogen, analysis is performed using a colorimetric method.

  That is, nitrate nitrogen and nitrite nitrogen contained in a sample can be quantified by absorption spectrophotometry. For example, in analysis using flow analysis, as shown in FIG. 2 described later, a sample containing nitrate nitrogen and nitrite nitrogen was injected into a carrier fluid flowing continuously, and this sample was injected. Nitrite nitrogen in the sample is developed by mixing and reacting the carrier liquid with a coloring reagent which reacts with nitrite nitrogen to develop color. Further, the same sample is allowed to react with the same color-developing reagent to reduce its color by reducing nitrate nitrogen contained in the sample through a reduction column to nitrite nitrogen. Then, the degree of color development that changes depending on the concentrations of nitrate nitrogen and nitrite nitrogen originally contained in the sample is measured and acquired as an absorbance signal. Next, using the calibration curve representing the relationship between the concentration of nitrate nitrogen and the absorbance, and the relationship between the concentration of nitrite nitrogen and the absorbance, obtained in advance, the concentration corresponding to the obtained absorbance is Identify. This makes it possible to quantify the concentration of nitrate nitrogen and the concentration of nitrite nitrogen contained in the sample. In addition, in the reduction column for reducing nitrate nitrogen contained in the sample to nitrite nitrogen, for example, according to JIS K 0170, it is confirmed that the reduction ratio is 0.9 or more every about 10 to 20 samples. It is supposed to be used from.

The method of determining the reduction rate is, for example, as follows. First, after passing a nitrite nitrogen standard solution of known concentration through a reduction column, the absorbance is measured. The concentration of the nitrite nitrogen standard solution at this time is C1, and the absorbance is A1. Similarly, after passing through a reduction column a nitrate nitrogen standard solution of known concentration, the absorbance is measured. The concentration of the nitrate nitrogen standard solution at this time is C2, and the absorbance is A2. The reduction rate can be expressed by the following equation. The nitrite nitrogen standard solution is a solution in which the component contributing to absorbance is only nitrite nitrogen, and the nitrate nitrogen standard solution is a solution in which the component contributing to absorbance is only nitrate nitrogen. It means that.
Reduction rate = (A2 / C2) / (A1 / C1)
In JIS K0170, C1 and C2 have the same concentration.

JP 2008-145297 A

Japan Industrial Standard JIS K 0170-2: 2011 Water quality test method by flow analysis method-Part 2: Nitrite nitrogen and nitrate nitrogen

From the absorbance of the sample reacted with the color developing reagent without passing through the reduction column and the absorbance of the sample reacted with the color developing reagent through the reduction column, the concentration of nitrate nitrogen and the concentration of nitrite nitrogen contained in the sample As a general method for performing quantification, for example, according to JIS K 0170 or JIS K 0102, the absorbance _{AT-Cd of} the sample passed through the reduction column and the nitrate nitrogen standard are not considered in the calculation in the calculation. _Considering the concentration C ' _NO3 obtained from the solution and the calibration curve obtained from the solution as the sum of the concentrations of nitrate nitrogen and nitrite nitrogen, and subtracting the concentration of nitrite nitrogen determined separately It is calculated as follows.

Here, _let the nitrate nitrogen concentration be C _NO3 and _let the nitrite nitrogen concentration be C _NO2 . Further, the absorbance by nitrate nitrogen when passing through the reduction column is _ANO3-Cd , and the absorbance by nitrite nitrogen when not passing through the reduction column is _ANO2 .
Considering the case of using a nitrate nitrogen standard solution, the absorbance A _NO3-Cd by nitrate nitrogen when passing through a reduction column can be expressed by the following equation. [Alpha] _NO3-Cd in the formula is a slope when a calibration curve showing the correspondence between the absorbance and the concentration of nitrate nitrogen in the nitrate nitrogen standard solution is approximated by a straight line. This calibration curve can be obtained using a nitrate nitrogen standard solution, and can be obtained from the absorbance when the nitrate nitrogen standard solution is passed through a reduction column.
A _NO3-Cd = α _NO3-Cd x C _NO3

Moreover, the light absorbency A _NO2 by nitrite nitrogen when not passing through a reduction column can be expressed by the following formula. In addition, (alpha) _{NO2 in} a formula is the inclination at the time of approximating the calibration curve when not passing a nitrite nitrogen standard solution through a reduction column calculated | required using the nitrite nitrogen standard solution by a straight line.
A _NO2 = α _NO2 × C _NO2
Here, the concentration C _'NO3 computed using a calibration curve of nitrate standard solution from the absorbance A _T-Cd when through a sample containing nitrate nitrogen and nitrite nitrogen in the reduction column ₍₌ A _{T -Cd} / _{α NO3-Cd)} is assumed to be the concentration _C T _{= C} NO2 _{+ C NO3} which is the sum of nitrate nitrogen and nitrite nitrogen contained in the sample.

Because it is _{C T = C 'NO3 = A} T-Cd / α NO3-Cd, concentration _{C NO3} of nitrate in the sample, a _{C NO2} obtained by analyzing without passing through the same sample to a reducing column It can be used to calculate from the following equation.
_{C NO3 = C T -C NO2 =} (A T-Cd / α NO3-Cd) -C NO2
However, strictly speaking, since the reduction rate is the reduction rate ≠ 1, taking the reduction rate into account, C ' _NO3 TC _T will result as described below, and an error occurs.

Here, the absorbance _AT-Cd when a sample containing nitrate nitrogen and nitrite nitrogen is passed through a reduction column is the absorbance A _NO2 by nitrite nitrogen originally contained in the sample when the sample is passed through a reduction column. _{It becomes the sum of -Cd} and the _{light absorbency ANO3 -Cd} by the nitrite nitrogen by which nitrate nitrogen contained from the sample originally was reduce _{| restored} by passing through a reduction column.
Further, the relationship between the absorbance A _{NO2 -Cd} by the nitrite nitrogen originally contained in the sample when passing through the reduction column and the concentration C _NO2 can be expressed by the following equation. In addition, (alpha) _NO2-Cd in a formula is the inclination at the time of approximating the calibration curve at the time of passing a nitrite nitrogen standard solution to a reduction column with a straight line calculated | required using the nitrite nitrogen standard solution.
A _NO2-Cd = alpha _NO2-Cd x C _NO2

Further, the reduction rate δ of the reduction column can be expressed by the following equation from the definition equation shown above.
δ = α _NO3-Cd / α _NO2-Cd
Using these, the relationship between the absorbance by nitrate nitrogen when passing through a reduction column and the concentration is represented by the following equation in consideration of the reduction rate.
A _NO3-Cd = α _NO3-Cd x C _NO3 = α _NO2-Cd x δ x C _NO3

From the above, the relationship between the measured absorbance _AT-Cd and the concentration and the reduction rate when a sample containing nitrate nitrogen and nitrite nitrogen is passed through a reduction column can be expressed by the following equation.
A _T-Cd = A _NO2-Cd + A _NO3-Cd
= Α _NO2-Cd x C _NO2 + α _NO3-Cd x C _NO3
= Α _{NO 2-} C d x C _NO 2 + α _{NO 2-} C d x δ x C _{NO 3}
= Α _{NO 2-} C d × (C _NO 2 + δ × C _{NO 3} )

Therefore, the following equation can be obtained for the concentration C ′ _{NO 3} obtained from the absorbance _{AT-Cd of the} sample containing nitrate nitrogen and nitrite nitrogen through the reduction column and the calibration curve of nitrate nitrogen.
C ' _NO3 = _AT-Cd / alpha _NO3-Cd
= Α _{NO 2-} C d × (C _NO 2 + δ × C _{NO 3} ) / α _{NO 3-} C d
= Α _{NO 2-Cd} x (C _NO 2 + δ x C _{NO 3} ) / (α _{NO 2-} C d x δ)
= (C _NO2 / δ) + C _NO3
≠ C _NO 2 + C _{NO 3} = C _T (for δ <1)
That is, <since the _{1, C 'NO3>} generally reduced rate [delta] [delta] becomes _{C T.}

From the above, if it contains a nitrite nitrogen and nitrate nitrogen in the sample _{and C 'is} regarded as NO3 = _{C T} nitrate nitrogen concentration _{C NO3 C'} obtained as NO3 _{-C NO2, C 'NO3} - C _NO2 = (A _T- C d / α _{NO 3-} C d)-C _{NO 2} = C _{NO 3} + (1-δ) / δ x C _{NO 2 In} practice, if the reduction ratio δ is not 1 (δ <1), It is understood that the value is calculated to be larger than that.

That is, since the reduction rate δ is not necessarily δ = 1 depending on the progress of the reduction reaction, the concentration calculation should be performed after the true reduction rate is determined. Therefore, the concentration C _NO3 of nitrate nitrogen in any sample should be calculated from the following equation.
C _NO3 = (A _T -C d / α _{NO 3} -C d)-(C _{NO 2} / δ)
That is, after the concentration C ' _NO3 is calculated, C _NO2 / δ corrected with the true reduction ratio δ should be subtracted.

Here, according to JIS K0170, it can be understood that the reduction rate is calculated for every 10 to 20 samples. This is to confirm that the concentration measurement can be performed with a certain degree of accuracy even if the reduction ratio is considered to be 1 when the reduction ratio is sufficiently close to 1 and concentration measurement is performed. If the reduction rate falls below 1, it is necessary to restore the reduction rate to a state sufficiently close to 1 by activating the reduction column. In order to calculate the reduction rate every approximately 20 samples, it is necessary to pass a nitrite nitrogen standard solution or nitrate nitrogen standard solution with a known concentration, which is usually not necessary for analysis, and extra analysis time is required. I need it. In addition, it takes a long time to perform the activation process, and analysis can not be performed during that time. On the other hand, if the true reduction ratio δ is not obtained, the calculation can not be performed using the reduction ratio δ, and the concentration calculation can not but be regarded as δ = 1, so that the error becomes large. That is, since C _T = C ′ _{NO 3} = A _T −C d / α _{NO 3} −C d does not strictly hold, an error is included when the reduction ratio δ is not used, that is, when the reduction ratio is regarded as 1. become.

In addition, when the concentration of nitrate nitrogen contained in any sample is measured, for example, every hour, it is necessary to frequently evaluate the reduction rate, and a color developing reagent is required each time, so the cost It also takes longer and analysis time.
The present invention has been made focusing on the above-mentioned unsolved problems, and it is a concentration that can measure or control the concentration with higher accuracy without time, labor, and cost of reagents. An object of the present invention is to provide a measurement method, a concentration management method, a concentration measurement device, and a concentration management device.

  According to one aspect of the present invention, a sample containing a first component and a second component to be reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component and the above The step of detecting the first absorbance by reacting with a color developing reagent that reacts only with the first component of the second component, and reacting the sample with the color developing reagent after passing through the reduction column, the second absorbance A detection step, an absorbance when a first component standard solution containing only the first component as a component reacting with the color developing reagent is reacted with the color developing reagent without passing through the reduction column, the first component Calculating a rate of change in absorbance, which is the ratio of absorbance when the standard solution is allowed to react with the color reagent after passing through the reduction column, and correcting the first absorbance using the rate of change in absorbance Before, after correction Detecting a difference between the first absorbance and the second absorbance; and a component that reacts with the color forming reagent after passing through the reduction column is only the first component formed by reducing the second component. The absorbance and the concentration of the second component in the second component standard solution before passing through the reduction column correspond to the absorbance when the two-component standard solution is passed through the reduction column and then reacted with the color forming reagent. Measuring the concentration of the second component in the sample before passing through the reduction column from the characteristic information obtained in advance and the difference.

  According to another aspect of the present invention, a sample containing a first component and a second component to be reduced to the first component by passing through a reduction column is not passed through the reduction column, and the first component and Detecting a first integrated equivalent value corresponding to an integrated value of absorbance in one continuous color development by reacting with a coloring reagent which reacts only to the first component among the second components; Detecting the second integrated equivalent value corresponding to the integrated value of absorbance in one continuous color development by reacting with the color forming reagent after passing through the reduction column, the first integrated equivalent value and the second integrated value Detecting the difference from the equivalent value, and a second component standard solution in which the component that reacts with the color forming reagent after passing through the reduction column is only the first component in which the second component is reduced. Passed through the reduction column Integrated equivalent value corresponding to the integrated value of absorbance in one continuous color development when reacted with the color developing reagent, and the second component in the second component standard solution before passing through the reduction column Measuring the concentration of the second component in the sample before passing through the reduction column from the characteristic information obtained in advance and the difference representing the correspondence with the concentration, and providing a concentration measurement method Be done.

  Further, according to another aspect of the present invention, a sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column. Detecting a first absorbance by reacting with a color developing reagent that reacts only with the first component among the component and the second component, and reacting the sample with the color developing reagent after passing through the reduction column; A step of detecting two absorbances, an absorbance when a first component standard solution containing only the first component as a component reacting with the color forming reagent is reacted with the color forming reagent without passing through the reduction column, Calculating a rate of change in absorbance which is a ratio of absorbance when the first component standard solution is allowed to react with the color developing reagent after passing through the reduction column, and using the first absorbance as the rate of change in absorbance And correct Obtaining a difference between the first absorbance and the second absorbance as a numerical value relating to the concentration of the second component in the sample before passing through the reduction column. .

  Further, according to another aspect of the present invention, a sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column. Detecting a first integrated equivalent value corresponding to an integrated value of absorbance in one continuous color development by reacting with a color developing reagent which reacts only to the first component among the component and the second component; and the sample After passing through the reduction column, the reaction with the color forming reagent to detect a second integrated equivalent value corresponding to an integrated value of absorbance in one continuous color development; the first integrated equivalent value and the second integrated equivalent value Obtaining a difference between the second integrated equivalent value as a numerical value related to the concentration of the second component in the sample before passing through the reduction column.

  Further, according to another aspect of the present invention, a sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column. A mode for measuring absorbance by reacting with a color developing reagent that reacts only with the first component among the component and the second component, and measuring the absorbance after reacting the sample with the color developing reagent after passing through the reduction column And an analyzer for measuring absorbance by switching between the following modes, and a first component standard solution containing only the first component as a component that reacts with the color developing reagent, and reacting with the color developing reagent without passing through the reduction column. Storage unit for storing the rate of change in absorbance which is the ratio of the absorbance when the first component standard solution is made to react with the coloring reagent after passing through the reduction column, and the two modes Measured by The second component standard solution in which the absorbance, the absorbance change rate, and the component that reacts with the color forming reagent after passing through the reduction column is only the first component in which the second component is reduced; Pre-acquired characteristics representing the correspondence between the absorbance when reacted with the color-forming reagent after passing through a reduction column and the concentration of the second component in the second component standard solution before passing through the reduction column And a concentration calculator configured to calculate the concentration of the second component in the sample before passing through the reduction column from the information.

  Furthermore, according to another aspect of the present invention, a sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column. A mode for measuring absorbance by reacting with a color developing reagent that reacts only with the first component among the component and the second component, and measuring the absorbance after reacting the sample with the color developing reagent after passing through the reduction column Of the second component in the sample before passing through the reduction column, based on the analyzer measuring the absorbance by switching between the two modes and the absorbance measured in the two modes. An equivalent value computing unit for computing integrated equivalent values respectively corresponding to integrated values of absorbance in one continuous color development measured in each of the two modes; After passing through the reduction column, a second component standard solution in which the component that reacts with the color developing reagent after passing through the reduction column is only the first component formed by reducing the second component is reacted with the color developing reagent Indicates the correspondence between the integrated equivalent value corresponding to the integrated value of absorbance in one continuous color development and the concentration of the second component in the second component standard solution before passing through the reduction column. The concentration of the second component in the sample before passing through the reduction column is calculated from the characteristic information acquired in advance and the difference between the two integrated equivalent values calculated by the integrated equivalent value calculator. There is provided a concentration measuring apparatus comprising: an arithmetic processing unit.

  Furthermore, according to another aspect of the present invention, a sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column. A mode for measuring absorbance by reacting with a color developing reagent that reacts only with the first component among the one component and the second component, and allowing the sample to react with the color developing reagent after passing through the reduction column An analyzer for measuring absorbance by switching the mode to be measured, and a first component standard solution containing only the first component as a component that reacts with the color developing reagent, without passing through the reduction column and reacting with the color developing reagent A storage unit for storing a rate of change in absorbance, which is a ratio of absorbance when the first component standard solution is made to react with the color reagent after passing through the reduction column; Measure in mode It said absorbance is from, and the absorbance change rate, and a calculation unit that acquires a numerical value relating to the concentration of the second component in the sample before passing the reduction column, the concentration management device provided is provided.

  Further, according to another aspect of the present invention, a sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column. A mode for measuring absorbance by reacting with a color developing reagent that reacts only with the first component among the component and the second component, and measuring the absorbance after reacting the sample with the color developing reagent after passing through the reduction column To obtain the numerical value of the concentration of the second component in the sample before passing through the reduction column, based on the analyzer measuring the absorbance by switching between the two modes and the absorbance measured in the two modes An integral equivalent value computing unit including an arithmetic operation unit, the arithmetic operation unit computing an integration equivalent value corresponding to an integrated value of absorbance in one continuous color development measured in each of the two modes; Serial integrated value corresponding concentration control device and an arithmetic processing unit for obtaining a difference between two integrated value corresponding to each other, which is calculated as a numerical value on the concentration of the second component in the calculating portion is provided.

  According to one aspect of the present invention, it is possible to measure and manage the concentration of nitrate nitrogen with higher accuracy while reducing time, labor, and cost of reagents.

It is a schematic block diagram which shows an example of the concentration measuring apparatus which concerns on one Embodiment of this invention. It is a schematic block diagram which shows an example of an analyzer. It is explanatory drawing for demonstrating the calculation method of a light absorbency change rate. It is explanatory drawing for demonstrating the calculation method of a light absorbency change rate. It is explanatory drawing for demonstrating the calculation method of a light absorbency change rate. It is a flowchart which shows an example of the process sequence at the time of absorbance change rate calculation. It is a flowchart which shows an example of the process sequence at the time of concentration measurement. It is a flowchart which shows an example of the process sequence at the time of standard curve acquisition. It is an example of a calibration curve. It is a flowchart which shows an example of the process sequence at the time of the density | concentration measurement in 2nd embodiment. It is a flowchart which shows an example of the process sequence at the time of standard curve acquisition of an absorbance area. It is an example of a calibration curve of absorbance area.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present invention. However, it is apparent that other embodiments can be practiced without being limited to such specific specific configurations. The following embodiments do not limit the invention according to the claims. Moreover, not all combinations of features described in the embodiments are essential to the solution of the invention.

First, a first embodiment of the present invention will be described.
FIG. 1 is a schematic configuration view showing an example of a concentration measuring apparatus 1 to which a concentration measuring method according to an embodiment of the present invention is applied. Here, the case where the concentration measurement apparatus 1 measures the concentration of nitrate nitrogen contained in seawater will be described.
For example, as shown in FIG. 1, the concentration measuring device 1 controls a water intake device 2 for taking seawater, an analyzer 3 for measuring the absorbance of a sample to be injected, and the water intake device 2 and the analyzer 3. The control device 4 calculates the concentration of nitrate nitrogen in the sample injected into the analysis device 3 based on the absorbance measured by the analysis device 3, and the concentration of nitrate nitrogen measured by the concentration measurement device 1 On the other hand, the monitoring of the nitrate nitrogen concentration is performed by the monitoring device 5 disposed at a place apart from the concentration measuring device 1, for example.

The water intake device 2 includes, for example, a submersible pump 21 that pumps up seawater, and a filter unit 22 that filters seawater that is pumped up by the submersible pump 21.
The analyzer 3 is composed of, for example, an analyzer that measures the absorbance of the sample by flow analysis, and as shown in FIG. 2, the nitrite nitrogen is not reacted with the nitrate nitrogen (second component) in the sample. (First component) A channel 30 into which a coloring reagent that reacts with only the first component is injected, a channel 31 in which the carrier liquid flows continuously, a liquid feed pump 32 provided in the channel 30 and the channel 31, water intake The injection valve 33 for injecting the seawater or standard solution obtained by the device 2 into the flow passage 31, the reduction column 34 (copper-cadmium reduction column) using copper-cadmium, and the injection valve 33 of the flow passage 31 A switching valve 35 for switching the flow path of the carrier liquid downstream between the first path R1 not passing through the reduction column 34 and the second path R2 passing through the reduction column 34 and the flow path 30 are supplied Chromogenic reagent and first route R1 The reaction coil 36 is mixed with the carrier liquid via the second route R2 and injected, and a flow cell 37 equipped with an absorbance measurement function for measuring the absorbance of the sample that has developed color by reacting with the coloring reagent in the reaction coil 36 And.

The submersible pump 21 and the valves of the analyzer 3 are controlled by the controller 4. The seawater that has been pumped and filtered by the submersible pump 21 is injected into the carrier liquid via the injection valve 33. The carrier liquid is selectively injected with seawater collected and filtered by the water intake device 2, which is a measurement target of the concentration of nitrate nitrogen, and a standard liquid as a sample.
The sample injected into the carrier liquid is mixed with the coloring reagent and injected into the reaction coil 36 through the first pathway R1 not through the reduction column 34 or the second pathway R2 through the reduction column 34. The sample injected into the reaction coil 36 is discharged to the outside of the reaction coil 36 after the reaction with the coloring reagent is promoted in the reaction coil 36 by a heating device or the like (not shown) to develop color. Thereafter, in the flow cell 37, the coloring condition of the sample generated by the reaction of the sample with the coloring reagent is measured as an absorbance signal, and is output to the control device 4.

  The controller 4 controls the submersible pump 21, the injection valve 33, and the switching valve 35, and an operation unit (concentration operation unit) that calculates the concentration of nitrate nitrogen in the sample based on the absorbance signal from the flow cell 37. 42, a storage unit 43 for storing various information such as an absorbance change rate 後 述 described later necessary for concentration calculation in the calculation unit 42 and a calibration curve, and a monitoring device of the concentration calculation result in the calculation unit 42 by wireless communication A communication unit 44 for transmitting data to the communication unit 5 and a power supply unit 45 for supplying electric power to the water intake device 2 and the analysis device 3 by solar power generation or a battery are provided.

The arithmetic unit 42 drives each part of the water intake device 2 and the analyzer 3 via the drive unit 41, acquires a calibration curve using a standard solution at a predetermined timing, and periodically or previously sets seawater at a predetermined timing. Take water and measure its nitrate nitrogen concentration. Then, the measurement result is transmitted to the monitoring device 5 via the communication unit 44.
The monitoring device 5 includes a communication unit 51 that performs wireless communication with the communication unit 44 of the control device 4, and a monitoring unit 52. The monitoring unit 52 receives nitrate nitrogen from the control device 4 via the communication unit 51. The concentration information is acquired, and abnormality monitoring is performed, for example, by comparing the information with a preset threshold value, and when an abnormality is detected, an alarm is issued to notify that an abnormality has occurred. In the monitoring unit 52, not only nitrate nitrogen concentration information but also, for example, the sum of nitrate nitrogen concentration and nitrite nitrogen concentration, concentration of nitrates being analyzed with nitrate nitrogen concentration and others Abnormality monitoring may be performed based on the sum of Further, the control device 4 and the monitoring device 5 are not limited to wireless communication, and concentration information and the like may be transmitted by wired communication.

Next, the calculation method of the nitrate nitrogen concentration in the calculation unit 42 will be described.
Here, when a sample containing nitrate nitrogen and nitrite nitrogen (for example, seawater) is passed through a reduction column, reacted with a coloring reagent, and its absorbance is measured, the absorbance obtained from this sample is originally nitrite It is the sum of the absorbance due to the component that was the state nitrogen and the absorbance due to the component where the nitrate nitrogen is reduced to become nitrite nitrogen. Therefore, the absorbance _AT-Cd obtained by measuring the sample passed through the reduction column is represented by the following formula. _ANO2-Cd in the following formula represents the absorbance by the component that was originally nitrite nitrogen when passing through the reduction column, and _ANO3-Cd is the nitrate nitrogen reduced to nitrite nitrogen It represents the absorbance by the components.
A _T-Cd = A _NO2-Cd + A _NO3-Cd

On the other hand, when passing through a reduction column, the relationship between the absorbance A _NO3-Cd by the nitrate nitrogen standard solution (second component standard solution) and the concentration C _NO3 of nitrate nitrogen is a straight line passing through zero as the reduction ratio It can be expressed by the following equation regardless of The term "nitrate nitrogen standard solution" as used herein refers to a solution in which the component contributing to the absorbance is only the component by nitrate nitrogen and the concentration of nitrate nitrogen is known.
A _NO3-Cd = α _NO3-Cd x C _NO3

This equation also holds for nitrate nitrogen in a sample containing nitrate nitrogen and nitrite nitrogen. Therefore, if _ANO2-Cd is known from both formulas, the nitrate nitrogen concentration can be calculated by the following formula without considering the reduction rate. The contribution of the reduction rate in the absorbance A _NO3-Cd of nitrate nitrogen in this case is contained in α _NO3-Cd .
C _NO3 = A _{NO3 -Cd} / α _{NO3 -Cd}
= ( _AT-Cd- A _NO2-Cd ) / [alpha] _NO3-Cd

Here, when the sample is passed through a reduction column, nitrate nitrogen contained in the sample is reduced to nitrite nitrogen, so the absorbance obtained from the sample passed through the reduction column was originally nitrate nitrogen Is the sum of the absorbance of the component reduced to nitrite nitrogen by passing through the reduction column and the absorbance of the component that was originally nitrite nitrogen. Therefore, when a sample is passed through a reduction column, the absorbance A _NO2-Cd by nitrite nitrogen originally contained in the sample before passing through a reduction column can not be measured directly.

On the other hand, the absorbance A _{NO2 of} only nitrite nitrogen contained in the sample before passing through the reduction column can be measured by measuring the absorbance of the sample without passing through the reduction column.
Therefore, the influence of the reduction column on the absorbance is separately determined, and the determined influence is used to measure the absorbance of the sample without passing through the reduction column, thereby correcting the absorbance A _NO2 to obtain the sample. Is passed through a reduction column, and the absorbance A _NO2-Cd by nitrite nitrogen contained in the sample from the beginning is estimated.

  Here, as shown in FIG. 2, a sample containing nitrite nitrogen and not containing nitrate nitrogen (for example, a nitrite nitrogen standard solution) injected into the carrier liquid is mixed while moving in the flow path 31. Diffusion occurs, and nitrite nitrogen in the sample reacts with the coloring reagent to develop color. At this time, the flow cell 37 measures the absorbance of the carrier liquid containing the sample and the coloring reagent at a predetermined sampling cycle. Therefore, the waveform of the absorbance signal obtained from the flow cell 37 is, for example, as shown in FIG. 3, the absorbance gradually increases with the passage of time as nitrite nitrogen contained in the sample passes through the flow cell 37. After that, the sample is discharged out of the flow cell 37, and the absorbance becomes zero. In FIG. 3, the horizontal axis is the measurement time of absorbance, and the vertical axis is the measurement value of absorbance for each sampling cycle.

  The mixing and diffusion of the sample is promoted as the flow path is longer and as the flow path is thicker. Since the inner diameter of the reduction column 34 is larger than the tube inner diameter of the flow path 31, the sample is more diffused into the carrier liquid when passing through the reduction column 34. The more diffuse the sample, the smaller the number of nitrite nitrogens contained per unit volume. That is, the maximum value of the absorbance is smaller.

  Therefore, as shown in FIG. 3, in the case of a sample containing nitrite nitrogen injected into the carrier liquid and not containing nitrate nitrogen, the sample moves in the channel 31 without passing through the reduction column 34 (characteristic line Compared to L1), when it is passed through the reduction column (characteristic line L2), the obtained absorbance has a lower value, and the absorbance is measured over a longer time. Therefore, when the sample containing nitrite nitrogen and not containing nitrate nitrogen is injected into the analyzer 3 in the waveform of the absorbance signal in one continuous color development, the peak value of the absorbance is the absorbance of the sample. The peak value of the absorbance differs depending on whether it passes through the reduction column 34 or not even though the concentration is the same.

From the above, it is considered that the rate of change of absorbance when passing through the reduction column and not passing through is determined by the geometrical size of the reduction column 34 regardless of the concentration of nitrite nitrogen. For this reason, when a sample containing nitrite nitrogen and nitrate nitrogen (for example, seawater) is passed through a reduction column, it is included in the sample containing nitrite nitrogen and nitrate nitrogen before passing through the reduction column. The absorbance A _NO2-Cd due to nitrite nitrogen can be determined if the ratio of absorbance with and without passing through a reduction column (hereinafter referred to as absorbance change rate η) when nitrite nitrogen is at a certain concentration is known. Even at such concentrations, it is considered that it can be uniformly determined from the absorbance A _NO2 due to only nitrite nitrogen which was originally contained in the sample before passing through the reduction column.

Therefore, the rate of change in absorbance 決定 is determined as in the following equation using the absorbance measured with and without passing through the reduction column 34 and the nitrite nitrogen standard solution having the same concentration. The term "nitrite nitrogen standard solution" as used herein refers to a solution in which the component contributing to absorbance is only nitrite nitrogen and the concentration of nitrite nitrogen is known.
η = A _NO2-Cd / A _NO2
From the above, the concentration C _NO3 of nitrate nitrogen in any sample can be expressed by the following equation.
_{C NO3 = (A T-Cd} -A NO2-Cd) / α NO3-Cd
= (A _T- C d-× x A _NO2 ) / α _{NO 3-} C d

For example, when the nitrite nitrogen standard solution, 10 [μmol / L] is passed through the first route R1 which does not pass through the reduction column 34 to measure the absorbance, the measurement result of the absorbance is the waveform shown in L1 in FIG. It becomes. In L1, the peak value of absorbance is taken as Amax1. Next, when the same nitrite nitrogen standard solution, 10 [μmol / L], is passed through the second route R2 passing through the reduction column 34 to measure the absorbance, the absorbance measurement result is L2 in FIG. It becomes a waveform shown. In L2, assuming that the peak value of absorbance is Amax2, Amax2 becomes Amax2 <Amax1. This is due to the change in the degree of dispersion caused by the widening and stretching of the flow path by passing through the reduction column 34.
From these results, the rate of change in absorbance η is calculated from the following equation.
η = A _NO2-Cd / A _NO2 = Amax2 / Amax1

The rate of change in absorbance η is determined by geometrical dimensions and can be regarded as a value unique to the analyzer 3.
For example, the calibration curve obtained using the nitrite nitrogen standard solution without passing through the reduction column 34 is as shown by L11 in FIG. 4 when the nitrite nitrogen concentration is 10 μmol / L. Absorbance shall be "0.15". In addition, the absorbance of the same nitrite nitrogen standard solution when passing through a reduction column is assumed to be “0.10” (L12). In addition, as shown in FIG. 5, as shown in L22, a calibration curve prepared using a nitrate nitrogen standard solution through a reduction column shows that the absorbance at a nitrate nitrogen concentration of 30 [μmol / L] is “0. 27), and the calibration curve prepared using a nitrous acid nitrogen standard solution through a reduction column showed an absorbance of “0.10” at a nitrous acid nitrogen concentration of 10 μmol / L as shown in L21. Then, a sample containing 30 [μmol / L] of nitrate nitrogen and 10 [μmol / L] of nitrite nitrogen is passed through the reduction column 34, and when it is reacted with a coloring reagent, the absorbance is “0.37 (= 0.10 + 0.27).

  Here, the nitrous acid nitrogen standard when passing through the reduction column 34 using the calibration curve L11 of the nitrite nitrogen standard solution without passing through the reduction column 34 shown in FIG. Convert to a predicted calibration curve that is expected to be obtained when obtained using a solution. Nitrite nitrogen standard solution, absorbance when 10 [μmol / L] is passed through the first route R1 not passing through the reduction column 34, same nitrite nitrogen standard solution, 10 [μmol / L] It is assumed that the rate of change in absorbance η, which is the ratio of absorbance when passing through the second path R2 passing through the reduction column 34, is, for example, "0.67." When the absorbance change rate η is used, the calibration curve L11 is converted as shown in the predicted calibration curve L12, and when measured using the nitrite nitrogen standard solution from the predicted calibration curve L12 without passing through the reduction column 34 The absorbance at a nitrite nitrogen concentration of 10 [μmol / L] is converted to “0.15 × 0.67 ≒ 0.10”.

If this absorbance "0.10" is subtracted from the absorbance "0.37" of the whole sample shown in FIG. 5, the difference is "0.37-0.10 = 0.27", which is the value of nitric acid in the sample It represents the absorbance by nitrogen. The absorbance “0.27” by the nitrate nitrogen obtained is converted to a nitrate nitrogen concentration by using the slope α _{NO 3 −C d} = 0.27 / 30 of the calibration curve L 11 of the nitrate nitrogen standard solution. It becomes [μmol / L]. That is, it corresponds to the actual nitrate nitrogen concentration.

Next, the processing procedure of the calculation unit 42 will be described.
FIG. 6 is a flowchart showing an example of the processing procedure at the time of absorbance change rate calculation. The calculation unit 42 executes the absorbance change rate calculation processing shown in FIG. 6 at the time of shipping etc., calculates the absorbance change rate 固有 unique to the analyzer 3, and stores the calculated change rate η in the storage unit 43.
First, the calculation unit 42 controls the analyzer 3 through the drive unit 41 using a nitrite nitrogen standard solution containing only nitrite nitrogen as a component contributing to the absorbance, and uses the nitrite nitrogen standard solution as a carrier. It injects into a solution and makes 1st route R1 pass (Step S1). The concentration of the nitrite nitrogen standard solution may not be known.

The nitrite nitrogen standard solution is mixed with the color developing reagent and injected into the reaction coil 36, and the absorbance of the nitrite nitrogen standard solution reacted with the color developing reagent is measured by the flow cell 37.
The arithmetic unit 42 reads the absorbance signal from the flow cell 37 and sequentially stores the absorbance signal in the storage unit 43 (step S2).
Next, the operation unit 42 controls the analyzer 3 through the drive unit 41, and injects, into the carrier solution, the same nitrite nitrogen standard solution as the nitrite nitrogen standard solution that has passed the first route R1. , And pass the second route R2 (step S3).

After passing through the reduction column, the nitrite nitrogen standard solution is mixed with the coloring reagent and injected into the reaction coil 36, and the absorbance of the nitrite nitrogen standard solution reacted with the coloring reagent is measured by the flow cell 37.
The calculation unit 42 reads the absorbance signal from the flow cell 37 and sequentially stores the absorbance signal in the storage unit 43 (step S4).

  Next, the computing unit 42 passes the peak value of the absorbance signal representing the absorbance in one continuous color development obtained from the nitrite nitrogen standard solution passed through the first route R1, and passes the second route R2 The ratio to the peak value of the absorbance signal representing the absorbance in one continuous color development obtained from the nitrite nitrogen standard solution is calculated as the absorbance change rate η, and the calculated absorbance change rate η is stored in the storage unit 43 (Step S5). Then, the process ends.

FIG. 7 is a flowchart showing an example of a processing procedure in the case of measuring the concentration of nitrate nitrogen contained in seawater. The calculation unit 42 measures the concentration periodically, such as every hour, or at a preset timing.
At the concentration measurement timing, the calculation unit 42 first determines whether to create a calibration curve (step S11). The calibration curve is created at a preset timing, for example, once a day. If it is time to create a calibration curve, obtain a calibration curve when a nitrate nitrogen standard solution with a known concentration, containing only nitrate nitrogen as a component contributing to absorbance, is passed through the reduction column 34 (step S12). Acquisition of this calibration curve is prepared by a known procedure.

  Specifically, as shown in FIG. 8, the operation unit 42 controls the analyzer 3 via the drive unit 41, for example, injects a nitrate nitrogen standard solution, which is the first concentration, into the carrier solution, and the reduction column The second route R2 is passed through 34 to react with the coloring reagent (step S21). Then, the calculation unit 42 reads the absorbance signal indicating the absorbance of the nitrate nitrogen standard solution that has reacted with the color developing reagent, which is measured by the flow cell 37, and sequentially stores the absorbance signal in the storage unit 43 (step S22).

  Then, if the absorbance signal is not obtained for a predetermined number of nitrate nitrogen standard solutions having different concentrations, the process returns from step S23 to step S24 and returns to step S21, and this time, for example, nitrate having a second concentration different The nitrogen standard solution is injected into the carrier solution, and the second route R2 is passed to acquire an absorbance signal (step S22). Then, when absorbance signals are acquired for predetermined numbers of nitrate nitrogen standard solutions having different concentrations, for example, nitrate nitrogen standard solutions of first to third concentrations, the process proceeds from step S23 to step S25 to acquire a calibration curve. . In addition, although the absorbance signal is acquired about the nitrate nitrogen standard solution of the first to the third concentration here, it is sufficient if the calibration curve can be acquired, for example, the first concentration and the second concentration The absorbance signal may be acquired only for the nitrate nitrogen standard solution of a certain type, or the absorbance signal may be acquired for any number of nitrate nitrogen standard solutions having different concentrations, and the calibration curve may be acquired based on this. Good.

  That is, based on the absorbance of the nitrate nitrogen standard solution which is the first to third concentration stored in the storage unit 43, the computing unit 42 calibrates the absorbance when the nitrate nitrogen standard solution passes through the second route R2. Create a line For example, as shown in FIG. 9, the abscissa represents the concentration [μmol / L] of the nitrate nitrogen standard solution, the ordinate represents the absorbance, and the ordinate represents the nitrate nitrogen standard solutions of the first to the third concentration. The peak value of the absorbance signal when passing through 34 is obtained, and a calibration curve is obtained based on these three points. The calibration curve thus obtained is stored in the storage unit 43. This completes the acquisition of the calibration curve. The calibration curve is a line segment represented by an approximate expression obtained from three points. For example, an approximate straight line may be obtained from these three points by the least squares method, and this straight line may be used as a calibration curve, or an approximate curve obtained from these three points may be used as a calibration curve. Also, for example, a straight line that always passes through the zero point may be determined by the least squares method and this may be used as a calibration curve. Further, a broken line passing through the three detected points may be used as a calibration curve. Furthermore, if a straight line or an approximate straight line passing through two points different from the zero point out of the three points is obviously deviated from the zero point, a straight line having the same slope as this straight line may be used as a calibration curve.

  Referring back to FIG. 7, when acquisition of the calibration curve of the nitrate nitrogen standard solution is completed, the process proceeds to step S13, and next, the calculation unit 42 controls the water intake device 2 and the analyzer 3 via the drive unit 41. Then, an absorbance measurement process is performed to measure the absorbance of seawater which is the measurement object of the concentration of nitrate nitrogen. That is, first, in step S13, seawater to be measured is injected into the carrier liquid and allowed to pass through the first route R1. Then, the absorbance signal of the sample that has been measured by the flow cell 37 and reacted with the coloring reagent is read and stored in the storage unit 43 (step S14).

Next, seawater to be measured is injected into the carrier liquid and allowed to pass through the second route R2 (step S15). Then, the absorbance signal of the sample, which has been measured by the flow cell 37 and reacted with the coloring reagent, is read and stored in the storage unit 43 (step S16).
Next, concentration calculation processing is performed based on the obtained absorbance.
First, a peak value is acquired from the absorbance signal when passing the first route R <b> 1, which is the seawater to be measured acquired in step S <b> 14. _{Let this} be an absorbance A _{NO2 to} which only nitrite nitrogen contained in seawater to be measured contributes. Moreover, a peak value is acquired from the light absorbency signal at the time of making the seawater of the measuring object pass at 2nd path | route R2 acquired by step S16. Let this be the absorbance _AT-Cd by the nitrite nitrogen contained in the seawater to be measured and the nitrate nitrogen reduced by passing through the reduction column 34 (step S17).

Next, the process proceeds to step S18, and the absorbances A _NO2 (first absorbance) and A _T-Cd (second absorbance) determined in step S17, and absorbance change rate η stored in the storage unit 43 and step S12 The nitrate nitrogen concentration C _NO3 in the seawater to be measured is calculated from the following equation (1) using the acquired gradient α _NO3-Cd (characteristic information) of the calibration curve of the nitrate nitrogen standard solution. Then, the nitrate nitrogen concentration C _NO3 in the seawater to be measured which is obtained is transmitted to the monitoring device 5 through the communication unit 44.
C _NO3 = (A _T- C d-× x A _{NO 2} ) / α _{NO 3} -C d (1)

Thus, the process at the time of concentration measurement is completed. Here, assuming that the calibration curve is a straight line, the absorbance is converted from concentration to concentration using the slope of the calibration curve, but the absorbance may be directly converted to the corresponding concentration using an approximate straight line or approximate curve of absorbance and concentration Good.
By executing this process at every concentration measurement timing, for example, the nitrate nitrogen concentration C _{NO3 in} seawater as a sample is periodically transmitted to the monitoring device 5. The monitoring device 5 monitors the received nitrate nitrogen concentration C _NO3 and, when the nitrate nitrogen concentration C _NO3 exceeds, for example, a threshold value, issues an alarm or the like to notify an abnormality to notify the operator of the nitrate nitrogen concentration C. An abnormality of _NO3 can be notified.

As described above, according to the concentration measurement device 1 according to the first embodiment of the present invention, the nitrate nitrogen concentration C _NO3 in the seawater to be measured is obtained from the equation (1). And in (1) Formula, " _AT-Cd " and "A _NO2 " are measured values obtained by measuring the light absorbency of seawater, and "eta" is a fixed value calculated beforehand and memorized. is there. Also, "α _{NO3 -Cd} " is a value obtained by acquiring a calibration curve. Except for the measurement of the absorbance of seawater, the measurement of absorbance using a coloring reagent or the like is only the calculation of the absorbance change rate η and the acquisition of a calibration curve. The calculation of the absorbance change rate η may be performed at least once while using the same reduction column, and the calibration curve may be obtained at a longer cycle or longer interval than the concentration measurement. Therefore, when performing concentration measurement, as compared with the case where it is confirmed periodically whether the reduction ratio ε of the reduction column is 0.9 or more as in the prior art, it takes time and effort to acquire the necessary parameters for concentration calculation In addition to the reaction with seawater for concentration measurement, the number of times the color developing reagent is required can be significantly reduced, and the cost can be reduced.

  In addition, in the concentration measuring device 1 according to one embodiment of the present invention, although the reduction rate is not used, the influence of the reduction rate not being 1 on the nitrite nitrogen contained in the absorbance after passing through the reduction column The contribution due to is accurately taken into account by using the rate of change of absorbance “η” determined by the geometrical dimensions of the analyzer 3 and by using a calibration curve with a nitrate nitrogen standard solution. As a result, the measurement error of the nitrate nitrogen concentration can be reduced.

  Thus, the nitrate nitrogen concentration in seawater can be automatically acquired at any timing. Therefore, when monitoring the water quality of the fish farm etc., the concentration measuring device 1 is installed in the fish farm, and the monitoring device 5 is installed in the building indoors, so that the operator remains in the building indoors. It is possible to monitor the water quality at that time at any time without moving or the like.

7 is provided in the calculation unit 42 when the concentration measurement command is notified from the monitoring unit 52, and the operator transmits the concentration measurement command in the monitoring unit 52, The operator may be configured to perform the measurement of the nitrate nitrogen concentration at a desired timing.
The rate of change in absorbance η may be calculated by the factory at the time of shipment, and when the concentration measuring device 1 is installed at the site, the rate of change in absorbance η during the first measurement of nitrate nitrogen concentration. You need to calculate Further, when the components of the analyzer 3 are replaced, etc., calculation of the absorbance change rate η may be performed at the installation place of the analyzer 3. Furthermore, the rate of change in absorbance η may be calculated and updated periodically while the device is in operation.

As described above, in the equation (1), (A _T -C d _-T x A _NO2 ) represents the absorbance of nitrate nitrogen in seawater to be measured. Also, since the absorbance is proportional to the concentration of nitrate nitrogen, monitoring the absorbance does not give the value of the exact concentration of nitrate nitrogen, but the degree of concentration of nitrate nitrogen (eg, normal, abnormal, etc.) In addition, it is also possible to estimate the change in concentration (for example, “the concentration is stable”, “the concentration is rising”, etc.), and the concentration can be calculated without using the calibration curve. Can manage the trend of

Next, a second embodiment of the present invention will be described.
The concentration measuring device 1 according to the second embodiment is intended to improve the measurement accuracy of the nitrate nitrogen concentration C _NO3 by using the absorbance area S instead of the absorbance change rate η. The processing is the same as that of the concentration measuring device 1 in the first embodiment except that the processing of the calculation unit 42 is different, so the same reference numerals are given to the same parts, and the detailed description thereof is omitted.

  As described above, for example, when nitrite nitrogen-containing samples of the same concentration and volume without nitrate nitrogen, such as nitrite nitrogen standard solutions, are passed through the first route R1 and the second route R2, respectively In addition, as shown in FIG. 3, the absorbance has a lower peak and a broader shape in the time axis direction when passing through the second route R2 where mixing and diffusion are more promoted. However, the “number of molecules in which the nitrite nitrogen and the coloring reagent have reacted” in the colored sample is the same for the case where the first route R1 passes and the case where the second route R2 passes.

  The absorbance is proportional to the concentration of molecules contributing to the absorption of light, that is, the number of molecules per unit volume, and the absorbance by all the molecules is detected. Therefore, when making samples of the same concentration and the same volume containing nitrite nitrogen and not nitrate nitrogen react with the coloring reagent and pass each through the first route R1 and the second route R2, measure the absorbance as shown in FIG. In the waveform of the absorbance signal in one continuous color development, where the abscissa represents the measurement time and the ordinate represents the absorbance, the area of the absorbance is the same regardless of the width and extension of the flow path.

  In the first embodiment, the change in the peak value of the absorbance due to the widening and stretching of the channel due to passage through the reduction column is corrected using the absorbance change rate η, but if the absorbance area is used, the same concentration And from the absorbance area after passing through a reduction column 34 a sample having the same volume and containing nitrate nitrogen and nitrite nitrogen, the absorbance area obtained without passing through the reduction column of nitrite nitrogen in the sample is By subtracting, the absorbance area by the nitrate nitrogen contained in the sample before passing through the reduction column 34 is obtained. Therefore, if a calibration curve representing the relationship between the absorbance area and concentration of the nitrate nitrogen standard solution in the case of passing through the reduction column 34 is obtained in advance, the absorbance area of nitrate nitrogen in the sample Concentration can be obtained. In this case, even if the reduction rate is not 1, since the reduction rate when acquiring the calibration curve and the reduction rate when analyzing the sample can be regarded as the same, nitrate nitrogen is not considered without considering the reduction rate. The concentration can be determined accurately.

The absorbance area of the sample containing nitrate nitrogen and nitrite nitrogen after passing through the reduction column can be obtained by measuring the absorbance of the sample passed through the reduction column 34. Also, the absorbance area of nitrite nitrogen in the sample can be obtained by measuring the absorbance of the sample without passing through the reduction column 34.
The concentration of nitrate nitrogen obtained in this manner is a value proportional to the number of nitrate nitrogen per unit volume in the sample, and is a value that does not increase or decrease in the path through which the sample passes, in the calculation process, or the like. Therefore, it is possible to measure more accurate nitrate nitrogen concentration proportional to the number of nitrate nitrogen molecules.

Here, the absorbance area by nitrite nitrogen in the sample is _SNO2 . The absorbance area S _NO2 by this nitrite nitrogen is measured by analysis not _passing through a reduction column.
Further, the absorbance area when a sample containing nitrate nitrogen and nitrite nitrogen is passed through a reduction column is defined as _ST-Cd .
The relationship between the absorbance area S _NO3-Cd of the absorbance by the nitrate nitrogen standard solution and the concentration when passing through the reduction column can be expressed by the following equation. The following equation represents a calibration curve when the relationship between the concentration and the absorbance area, which is obtained from the nitrate nitrogen standard solution, is represented by a straight line.
S _NO3-Cd = α _NO3-CdS x C _NO3

Therefore, the concentration C _NO3 of nitrate nitrogen in any sample can be calculated by the following equation.
C _NO3 = (S _T- C _d -S _{NO 2} ) / α _{NO 3} -C _d S
Next, the processing procedure of the calculation unit 42 will be described.
FIG. 10 is a flow chart showing an example of the processing procedure in the case of measuring the concentration of nitrate nitrogen contained in seawater. The calculation unit 42 measures the concentration periodically, such as for a fixed time, or at a preset timing.

  At the concentration measurement timing, the calculation unit 42 first determines whether to acquire a calibration curve of the absorbance area (step S31). The calibration curve of the absorbance area is acquired at a preset timing, such as once a day, for example. When it is time to acquire the calibration curve of the absorbance area, the calibration curve of the absorbance area is acquired using a nitrate nitrogen standard solution having a known concentration and containing only nitrate nitrogen as a component contributing to the absorbance ( Step S32).

  Specifically, as shown in FIG. 11, the computing unit 42 controls the analyzer 3 via the driving unit 41, and for example, a second path for passing the nitrate nitrogen standard solution, which is the first concentration, through the reduction column. R2 is allowed to pass to react with the color developing reagent (step S41). Then, the calculation unit 42 reads the absorbance signal representing the absorbance of nitrate nitrogen reacted with the coloring reagent measured by the flow cell 37, integrates the absorbance changing with the lapse of the measurement time, and uses the nitrate nitrogen standard solution. The integrated value of the resulting absorbance (hereinafter referred to as absorbance integrated value) is calculated. Then, the obtained integrated value of absorbance, that is, the area of the absorbance signal obtained in one continuous color development is stored as the absorbance area in the storage unit 43 (step S42).

  Then, if the absorbance integrated value is not obtained for the predetermined number of nitrate nitrogen standard solutions having different concentrations, the process returns from step S43 to step S44 through step S44, and this time, for example, the second concentration different from the first concentration The nitrate nitrogen standard solution is allowed to pass through the second route R2 to acquire the absorbance integrated value (step S42). When the integrated value of absorbance is acquired for a predetermined number of nitrate nitrogen standard solutions having different concentrations, for example, nitrate nitrogen standard solutions of first to third concentrations, the process proceeds from step S43 to step S45 to acquire a calibration curve. Do.

  That is, from the absorbance area obtained by measuring the nitrate nitrogen standard solution which is the first to the third concentration stored in the storage unit 43, the absorbance area when the nitrate nitrogen standard solution passes through the second route R2 Obtain a calibration curve of That is, as shown in FIG. 12, the abscissa represents the concentration [μmol / L] of the nitrate nitrogen standard solution, the ordinate represents the absorbance area, the nitrate nitrogen standard solution of the first to third concentrations, and the reduction column 34 A calibration curve is acquired based on three points which become an absorbance area when passing through. The calibration curve of the absorbance area thus obtained is stored in the storage unit 43. This completes the acquisition of the calibration curve of the absorbance area. The calibration curve may be acquired in the same procedure as the process of step S25 in the first embodiment. Also in this case, it is sufficient that the calibration curve can be obtained without being limited to the three types of concentrations, for example, absorbance signals are obtained only for the two types of nitrate nitrogen standard solutions of the first concentration and the second concentration. Alternatively, the absorbance signal may be obtained for an arbitrary number of nitrate nitrogen standard solutions having different concentrations, and a calibration curve may be obtained based on this.

Returning to FIG. 10, when the acquisition of the calibration curve of the absorbance area is completed, the process proceeds to step S33, and next, the intake device 2 and the analyzer 3 are controlled via the drive unit 41 to obtain nitrate nitrogen. Absorbance measurement processing is performed to measure the absorbance of seawater, the concentration of which is to be measured. That is, first, in step S33, seawater to be measured is injected into the carrier liquid and allowed to pass through the first route R1 to react with the coloring reagent. Then, the calculation unit 42 reads an absorbance signal representing the absorbance of the seawater that has reacted with the color reagent, which is measured by the flow cell 37, sequentially integrates the absorbances, and stores the absorbance area as the absorbance area (step S34). That is, the absorbance area S _NO2 of the nitrite nitrogen component in seawater is calculated and stored in the storage unit 43.

Next, seawater to be measured is injected into the carrier liquid, passed through the second route R2, and reacted with the coloring reagent (step S35). Then, the calculation unit 42 reads the absorbance signal representing the absorbance of the sea water reacted with the coloring reagent measured by the flow cell 37, sequentially integrates the absorbances, and stores it as the absorbance area ST _-Cd in the storage unit 43 (step S36).
Then, the process proceeds to step S37, and the absorbance area S _T-Cd (second integrated equivalent value) obtained in step S36 and the absorbance area S _NO2 (first integration due to the nitrite nitrogen component in seawater obtained in step S34) The nitrate nitrogen concentration C _NO3 in seawater is calculated from the following equation (2) using the corresponding value) and the gradient α _NO3-CdS (characteristic information) of the calibration curve acquired in step S32. Then, the nitrate nitrogen concentration C _NO3 in the seawater that has been obtained is transmitted to the monitoring device 5 via the communication unit 44.
C _NO3 = (S _T -C _d -S _{NO 2} ) / α _{NO 3} -C _d S (2)

Thus, the process at the time of concentration measurement is completed. Here, assuming that the calibration curve is a straight line, the absorbance is converted from concentration to concentration using the slope of the calibration curve, but the absorbance may be directly converted to the corresponding concentration using an approximate straight line or approximate curve of absorbance and concentration. Good.
By performing this process at each concentration measurement timing, for example, the nitrate nitrogen concentration in seawater to be measured is periodically transmitted to the monitoring device 5. The monitoring device 5 monitors the received nitrate nitrogen concentration, and notifies the operator of the nitrate nitrogen concentration abnormality by emitting an alarm or the like notifying the abnormality when the nitrate nitrogen concentration exceeds, for example, a threshold value. Can.

Here, the processing of step S34 and step S36 corresponds to the integration equivalent value calculation unit, and the processing of step S37 corresponds to the calculation processing unit.
As described above, according to the concentration measurement device 1 according to the second embodiment of the present invention, the nitrate nitrogen concentration in the sample is obtained from the above-mentioned equation (2). And in (2) Formula, " _{ST -Cd} " and "S _NO2 " are measured values obtained by measuring the light absorbency of a sample, and "(alpha) _NO3-CdS " is created by preparing a calibration curve. It is a value to be obtained. Apart from the measurement of the absorbance of the sample, the measurement of the absorbance using a chromogenic reagent etc. is only the measurement of the calibration curve of the absorbance area, there is no need to evaluate the reduction ratio of the reduction column and there is no need to use the reduction ratio in the first place . Therefore, also in the concentration measurement apparatus 1 in the second embodiment, when performing concentration measurement, it is compared with the case where it is periodically confirmed whether the reduction ratio ε of the reduction column 34 is 0.9 or more as in the conventional case. As a result, it is possible to greatly reduce the time and effort required to acquire the parameters necessary for concentration calculation, and to significantly reduce the number of times the color reagent is required in addition to reacting with the sample for concentration measurement. Cost reduction can be achieved.

Further, in the concentration measuring device 1 according to the second embodiment of the present invention, the contribution of nitrite nitrogen contained in the absorbance after passing through the reduction column is the absorbance area due to the fact that the reduction ratio is not 1 Since the value is accurately taken into consideration and eliminated by using the calibration curve of the nitrate nitrogen standard solution, the measurement error of the nitrate nitrogen concentration can be reduced.
In the second embodiment, although the case where the nitrate nitrogen concentration is calculated using the absorbance area has been described, the present invention is not limited to this. As shown in FIG. 3, the absorbance is represented by a curve that is approximately symmetrical and convex upward. Therefore, for example, a value determined from the half value width of the absorbance and the peak value may be used as an index corresponding to the absorbance area, and a value having a correlation with the absorbance area may be used as the index.

Further, also in the second embodiment, the communication between the control device 4 and the monitoring device 5 may transmit concentration information or the like by wired communication instead of wireless communication.
Also in the second embodiment, (S _{T -C d} -S _NO 2) in the above-mentioned equation (2) represents the absorbance of nitrate nitrogen in seawater to be measured, and the absorbance is proportional to the concentration of nitrate nitrogen Therefore, by monitoring the absorbance, the level of nitrate nitrogen concentration (eg, normal, abnormal, etc.) and the change in concentration (eg, “concentration It is possible to infer “stable”, “the concentration is rising”, and the like, and concentration trend management can be performed without calculating the value of the concentration using a calibration curve.

  In each of the above embodiments, seawater containing nitrate nitrogen and nitrite nitrogen is the object to be measured, and the seawater as the object to be measured is passed through a reduction column to obtain nitrate nitrogen contained in the seawater. Although the case of measuring the concentration of is described, it is not limited thereto. The present invention can be applied to the case where the concentration of the second component in the sample is measured in a sample containing only the first component as a component contributing to the absorbance and the second component that becomes the first component by reduction. .

  Further, in each of the above embodiments, the nitrate nitrogen concentration measured by the concentration measuring device 1 is transmitted to the monitoring device 5 by wireless communication, and the nitrate nitrogen concentration is disposed at a location distant from the concentration measuring device 1 Although the case of monitoring by the monitoring device 5 has been described, the present invention is not limited to this. The function of the monitoring unit 52 of the monitoring device 5 may be provided on the concentration measuring device 1 side, and the nitrate nitrogen concentration may be monitored on the concentration measuring device 1 side.

  Further, the analysis device 3 is provided with a communication unit for transmitting the absorbance signal of the flow cell 37 by wireless communication, and the absorbance signal of the flow cell 37 is received by the control device 4. Control placed at a location distant from the analysis device 3 The nitrate nitrogen concentration may be measured in the device 4 and monitored. The point is that as long as the water intake device 2, the analyzer 3 and the controller 4 are provided, they may be arranged at the same place, or they may be arranged at different places, and how each part is arranged It is also good.

  The scope of the present invention is not limited to the illustrated and described exemplary embodiments, but also includes all the embodiments that bring about the same effects as the object of the present invention. Further, the scope of the present invention can be defined by any desired combination of particular features of all the disclosed respective features.

DESCRIPTION OF SYMBOLS 1 concentration measurement apparatus 2 water intake apparatus 3 analyzer 4 control apparatus 5 monitoring apparatus 30 flow path 31 flow path 34 reduction column 36 reaction coil 37 flow cell 42 calculation part 43 storage part

Claims (11)

A sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component among the first component and the second component. Detecting a first absorbance by reacting with a coloring reagent that reacts only with
Reacting the sample with the chromogenic reagent after passing through the reduction column to detect a second absorbance;
An absorbance when the first component standard solution containing only the first component as a component to be reacted with the color developing reagent is reacted with the color developing reagent without passing through the reduction column; Calculating a rate of change in absorbance, which is a ratio of absorbance when the reaction with the coloring reagent is performed after passing through a reduction column;
Correcting the first absorbance using the absorbance change rate, and detecting a difference between the corrected first absorbance and the second absorbance;
After passing through the reduction column, a second component standard solution in which the component that reacts with the color development reagent after passing through the reduction column is only the first component formed by reduction of the second component is The reduction based on previously obtained characteristic information indicating the correspondence between the absorbance when reacted and the concentration of the second component in the second component standard solution before passing through the reduction column, and the difference Measuring the concentration of the second component in the sample before passing through a column;
A method of measuring a concentration comprising: A sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component among the first component and the second component. Detecting a first integrated equivalent value corresponding to an integrated value of absorbance in one continuous color development by reacting with a coloring reagent that reacts only with
Allowing the sample to pass through the reduction column and then reacting with the color-forming reagent to detect a second integrated equivalent value corresponding to an integrated value of absorbance in one continuous color development;
Detecting a difference between the first integrated equivalent value and the second integrated equivalent value;
After passing through the reduction column, a second component standard solution in which the component that reacts with the color development reagent after passing through the reduction column is only the first component formed by reduction of the second component passes through the color development reagent and The correspondence between the integrated equivalent value corresponding to the integrated value of absorbance in one continuous color development when reacted and the concentration of the second component in the second component standard solution before passing through the reduction column Measuring the concentration of the second component in the sample before passing through the reduction column from the characteristic information obtained in advance and the difference.
A method of measuring a concentration comprising:   The method according to claim 1 or 2, wherein the first component is nitrite nitrogen and the second component is nitrate nitrogen.   The method according to claim 3, wherein the reduction column is a copper-cadmium reduction column. A sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component among the first component and the second component. Detecting a first absorbance by reacting with a coloring reagent that reacts only with
Reacting the sample with the chromogenic reagent after passing through the reduction column to detect a second absorbance;
An absorbance when the first component standard solution containing only the first component as a component to be reacted with the color developing reagent is reacted with the color developing reagent without passing through the reduction column; Calculating a rate of change in absorbance, which is a ratio of absorbance when the reaction with the coloring reagent is performed after passing through a reduction column;
The first absorbance is corrected using the rate of change in absorbance, and the difference between the first absorbance and the second absorbance after correction is taken as the concentration of the second component in the sample before passing through the reduction column. Obtaining as a numerical value for
A concentration management method comprising: A sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component among the first component and the second component. Detecting a first integrated equivalent value corresponding to an integrated value of absorbance in one continuous color development by reacting with a coloring reagent that reacts only with
Allowing the sample to pass through the reduction column and then reacting with the color-forming reagent to detect a second integrated equivalent value corresponding to an integrated value of absorbance in one continuous color development;
Acquiring a difference between the first integrated equivalent value and the second integrated equivalent value as a numerical value related to the concentration of the second component in the sample before passing through the reduction column Management method. A sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component among the first component and the second component. Analysis by measuring the absorbance by switching between the mode of measuring absorbance by reacting with a color developing reagent that reacts only with the sample, and the mode of reacting the sample with the color forming reagent after passing through the reduction column A device,
An absorbance when the first component standard solution containing only the first component as a component to be reacted with the color developing reagent is reacted with the color developing reagent without passing through the reduction column; A storage unit for storing a rate of change in absorbance, which is a ratio of absorbance when reacted with the color-forming reagent after passing through a reduction column;
The absorbance measured in the two modes, the rate of change in absorbance, and the component that reacts with the coloring reagent after passing through the reduction column are only the first component formed by reducing the second component. Correspondence between the absorbance when the second component standard solution passes through the reduction column and the reaction with the color reagent and the concentration of the second component in the second component standard solution before passing through the reduction column A concentration calculation unit that calculates the concentration of the second component in the sample before passing through the reduction column from the characteristic information obtained in advance, which represents
A concentration measuring device comprising: A sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component among the first component and the second component. Analysis by measuring the absorbance by switching between the mode of measuring absorbance by reacting with a color developing reagent that reacts only with the sample, and the mode of reacting the sample with the color forming reagent after passing through the reduction column A device,
And a concentration calculator configured to calculate the concentration of the second component in the sample before passing through the reduction column based on the absorbance measured in the two modes.
The concentration calculation unit is an integration equivalent value calculation unit that calculates integration equivalent values corresponding to integration values of absorbance in one continuous color development measured in each of the two modes;
After passing through the reduction column, a second component standard solution in which the component that reacts with the color development reagent after passing through the reduction column is only the first component formed by reduction of the second component passes through the color development reagent and The correspondence between the integrated equivalent value corresponding to the integrated value of absorbance in one continuous color development when reacted and the concentration of the second component in the second component standard solution before passing through the reduction column Calculate the concentration of the second component in the sample before passing through the reduction column from the characteristic information obtained in advance and the difference between the two integrated equivalent values calculated by the integrated equivalent value calculating unit Operation processing unit,
A concentration measuring device comprising:   9. The concentration measuring device according to claim 7, further comprising a wireless communication unit that transmits the concentration of the second component calculated by the concentration calculating unit by wireless communication. A sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component among the first component and the second component. Analysis by measuring the absorbance by switching between the mode of measuring absorbance by reacting with a color developing reagent that reacts only with the sample, and the mode of reacting the sample with the color forming reagent after passing through the reduction column A device,
An absorbance when the first component standard solution containing only the first component as a component to be reacted with the color developing reagent is reacted with the color developing reagent without passing through the reduction column; A storage unit for storing a rate of change in absorbance, which is a ratio of absorbance when reacted with the color-forming reagent after passing through a reduction column;
An arithmetic unit for acquiring a numerical value related to the concentration of the second component in the sample before passing through the reduction column from the absorbance measured in the two modes and the absorbance change rate;
A concentration management device comprising: A sample containing a first component and a second component reduced to the first component by passing through a reduction column is not passed through the reduction column but the first component among the first component and the second component. Analysis by measuring the absorbance by switching between the mode of measuring absorbance by reacting with a color developing reagent that reacts only with the sample, and the mode of reacting the sample with the color forming reagent after passing through the reduction column A device,
An arithmetic unit for acquiring a numerical value related to the concentration of the second component in the sample before passing through the reduction column, based on the absorbance measured in the two modes;
The calculation unit is an integration equivalent value calculation unit that calculates integration equivalent values corresponding to integration values of absorbance in one continuous color development measured in each of the two modes;
An arithmetic processing unit that acquires a difference between two integrated equivalent values calculated by the integrated equivalent value calculation unit as a numerical value related to the concentration of the second component;
A concentration management device comprising:

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