JPH10282083A - Method for measuring ammonium ion in water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring ammonium ion in water by which an accurate measured value can be obtained by minimizing measurement errors even in an area where the relative concentration of ammonium ions is high by using a flow injection method. SOLUTION: In a method for measuring ammonium ion in water, the concentration of ammonium ions in sample water in a high-concentration area B is measured by using a flow injection method after the sample water is diluted or shifted to a low-concentration area A by utilizing the flow rate characteristic. For diluting the sample water, a means which dilutes the sample water 2 by mixing the water 2 fed from a constant-flow pump with diluting water 12 fed from another constant-flow pump by using T- or Y-type connecting parts 13 and pump rotation controllers and control mechanisms respectively installed to the constant-flow pumps are provided and the flow rates of the sample water 2 and diluting water 12 from the pumps are controlled by selecting an appropriate rate of dilution out of the rates of dilution set in the control mechanisms and conveying the selected rate of dilution to the pump rotation controllers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the concentration of ammonium ion in water using the principle of flow injection analysis.

[0002]

2. Description of the Related Art In general, as a method for measuring the concentration of ammonium ion (NH ₄ ⁺ ) existing in water of rivers and lakes, there are ion chromatography, colorimetry, neutralization titration, ion electrode method and flow injection method. Is conventionally used.

[0003] Among them, ion chromatography, which is classified as instrumental analysis, is a type of high-performance liquid chromatography using an ion exchange column and has been developed for systematic analysis of inorganic anions and cations. Thus, various inorganic anions, which have conventionally been difficult to measure and analyze, can be quantified. Specifically, ammonium ions can be measured from a concentration of several ppm to several tens of ppm using a conductivity detector, but the measurement time requires several minutes to about 10 minutes after introduction of the sample. The quantification range is 0.1 to 30 (m
g / l).

[0004] The colorimetric method is a method in which a reagent is put into a water sample as a sample, and the absorbance at a specific wavelength is measured from a chemical reaction formula equivalent to the substance to be measured, thereby continuously measuring ammonium ions. A typical method is the indophenol blue absorption spectrophotometry for measuring the absorbance at 630 nm of indophenol blue produced by reacting with phenol in the coexistence of hypochlorite ion to determine the ammonium ion concentration. Has a relatively high concentration of 1.6 to 33 (mg / l).

In the neutralization titration method, ammonia extracted by performing a pretreatment by distillation is converted into a fixed amount of sulfuric acid (25 mmol / l).
This is a method for titrating ammonium ion by quantifying the solution absorbed therein with a 50 (mmol / l) sodium hydroxide solution, and the quantification range is from 0.3 to 40 (mg / l).
l) and relatively high concentration.

In the ion electrode method, a sodium hydroxide solution is added to a pretreated sample to adjust the pH to 11 to 13 to change ammonium ions to ammonia, and the potential is measured using an indicator electrode (ammonia electrode). Method for quantifying ammonium ions by using a quantification range of 0.1 to 100.
(Mg / l), which is quite high.

In the flow injection method, as shown in the schematic diagram of FIG. 7, a reagent solution (sodium hypochlorite, NaClO) is injected into a reaction vessel 1 by injection of a reaction reagent 1.
While falling continuously in 1, in this flow, the sample water 2 containing ammonium ions sequentially fed by the driving of the constant flow rate pump P _1, at the same time air 3 constant flow rate pump P ₂
Is driven continuously to cause a reaction in the mixing coil 4. The obtained reaction product enters the vaporizer 5 and the gas is separated into the gaseous phase by the vaporization and separation of the gas dissolved in the liquid phase.

[0008] The obtained gas components enter the heating oxidation furnace 6 and
Waste vaporizer separator 5 is discharged as waste fluid 7 by the driving of the pump P _3. This gas component is converted into nitric oxide (NO) by being heated in the heating oxidation furnace 6, and the sample gas flows into the decompression type chemiluminescence detector 8.
P ₄ is an exhaust pump that reduces the pressure in the chemiluminescence detector 8 and exhausts the gas after measurement. The chemiluminescence detector 8 is injected with the ozone gas obtained by the ozone generator 9, detects the chemiluminescence intensity generated by the reaction between NO and O ₃ (ozone gas) in the sample gas, and detects the intensity of the injected reaction reagent 1. The concentration of ammonium ions contained in the sample gas is measured based on the relationship between the type and the chemiluminescence intensity, and the signal output 20 is input to an arithmetic and control unit (not shown), converted into a concentration, and recorded on a display and a printer.

The signal output 20 is used to control the temperature of the heating oxidation furnace 6, control the operation / stop of the ozone generator 9, control the injection of the reaction reagent 1, and operate the pumps P ₁ , P ₂ , P ₃ and P ₄ . / Stop control signal.

The injection operation of the reaction reagent 1, the concentration conversion calculation processing of the luminescence intensity, and the setting of the conditions for automatic measurement are shown in FIG.
The device operation such as display of measured values and calibration operation is performed by a graphic touch panel 11 or the like as an interface. A measurement signal and a device management signal such as temperature are input to the sequencer 10 as an analog signal A, and signals for controlling the operation of various electromagnetic valves and the injection amount of the reaction reagent 1 and the like as control signals B and B ′ from the sequencer 10. Is output.

A signal C for various operations and device setting changes is input from the graphic touch panel 11 to the sequencer 10, and a display signal of measured values and a device management information signal D are output from the sequencer 10 to the graphic touch panel 11. Is done.

In particular, the flow injection method is useful for measuring the concentration of ammonium ions in the form of nitrogen dissolved in raw water for drinking water such as rivers. In addition to the hypochlorous acid solution, a potassium iodide solution or a titanium trichloride solution is used. Are sequentially added to the sample water 2 as reagents, and the measurement is carried out by detecting the amount of chemiluminescence as a peak of nitric oxide concentration proportional to ammonium ion using a chemiluminescent nitric oxide detector. .

The characteristics of such a method for measuring ammonium ions using the flow injection method are that the response is extremely fast, the measurement time is greatly reduced, and the measurement range is low because the linear range of the calibration curve is large. It is extremely wide from a high concentration to a high concentration, and has high accuracy and high reproducibility. Furthermore, since the measurement is performed in a gas phase system separated from the liquid phase, even when impurities such as suspensions are contained in the sample water, vaporization and separation are performed by simply performing pretreatment such as filtration. There is no contamination of the piping system at the front stage of the detector 5, and therefore, it is necessary to quickly measure samples other than sewage treatment water, river water, lake water, etc., and even more contaminated samples without affecting the detector body. Becomes possible.

[0014]

In the above-mentioned various methods for measuring ammonium ions, in the case of ion chromatography, the quantification range can be made to a relatively low concentration, but the measurement time excluding the pretreatment and the time for preparing a calibration curve is required. A few minutes to 10
It requires a considerable amount of time, such as minutes, and the presence of suspended substances (such as turbid components in water) or organic components in the test water will interfere with the measurement. There is. In addition, continuous measurement of river water, lake marsh water, sewage treatment water, and the like except tap water is difficult due to insufficient response to dirt.

The colorimetric method is a method in which a reagent is put into a test water as a sample, and the absorbance at a specific wavelength is measured from a chemical reaction formula equivalent to the substance to be measured, thereby continuously measuring ammonium ions. Pretreatment, color development, absorbance measurement and many manual analysis operations are required.
A large amount of about 0 ml is required, and the measurement time is 30 minutes to 1 hour or more in all the steps. In addition, since the measurement principle is based on colorimetry, measurement at the ppm level is possible,
In the case of measurement at the ppb level, there is a problem that practical use and automation are difficult because the measurement error increases.

Furthermore, the neutralization titration method and the anion electrode method are both complicated in operation and require a long time for measurement, and the quantification range is considerably high. There are drawbacks.

On the other hand, according to the measurement method using the flow injection method, the responsiveness is fast, the measurement time is greatly reduced, and the measurement range is extremely wide from low to high concentrations, and the measurement is performed with high accuracy and repetition. However, as shown in the graph of FIG. 9, there is no linearity between the relative value of the ammonium ion concentration and the relative value with the output intensity in the high concentration region, and a measurement error occurs. There is fear.

In the ordinary ammonium ion concentration measurement, it is general to prepare a calibration curve connecting two points, ie, a zero point and a span point, with a straight line, and obtain a measured value based on the calibration curve. In general, when the characteristic shown in the graph is present, a multi-order approximation formula is created and used as a calibration curve. However, if there is an error in the approximation formula itself, the error is reflected in the measurement error, and a problem arises in that an accurate measurement value cannot be obtained.

In particular, as described above, the present invention can be applied to the operation in the concentration of ammonium ions in the form of nitrogen dissolved in raw water for drinking water or in sewage. Has a big problem.

In view of the above, the present invention has been made in view of the above. Even when the relative value of the ammonium ion concentration is in a high concentration region, the measurement error is minimized, and an accurate measurement value can be obtained by using a flow injection method. It is an object of the present invention to provide a method for measuring ammonium ions in water which can be obtained.

[0021]

According to the present invention, in order to achieve the above object, a sample water containing ammonium ions in a reaction reagent is supplied to a fluid pump while the reaction reagent is caused to flow down in a flow channel capillary. After inflow mixing by driving, gas component separated from liquid phase by vaporization separator is converted to nitric oxide in heating oxidizing furnace, chemiluminescence intensity is detected by detector and ammonium ion in gas phase is quantified. In the method for measuring ammonium ions in water, the concentration of ammonium ions was measured by the flow injection method after the sample water in the high concentration region was shifted to the low concentration region by diluting the sample water at an optimal dilution ratio with a diluting device. The present invention provides a method for measuring ammonium ion, in which a measurement value is obtained by performing a back calculation according to a dilution factor.

As the above-mentioned dilution method, means for mixing and diluting the sample water and the dilution water fed by the constant flow rate pump using a T-type or Y-type connecting part, and a pump speed controller and control for each constant flow rate pump A mechanism is provided, and the dilution ratio of the water to be measured is set in a plurality of stages in advance in the control mechanism,
By selecting an appropriate magnification from among these dilution magnifications, a signal corresponding to the dilution magnification is output from the control mechanism and transmitted to the pump speed controller to control the flow rate of each constant flow pump for sample water and dilution water. To do it.

As still another dilution method, a dispenser for quantifying sample water, a dispenser for quantifying dilution water, and a mixing tank are prepared.
The suction / discharge operation of the sample water by the dispenser for quantifying the sample water and the suction / discharge operation of the diluent water by the dispenser for quantifying the dilution water appropriately adjust the ratio of the sample water and the dilution water in the mixing tank. A pump speed controller and a control mechanism are provided for a constant flow pump for sample water, and a plurality of stages of pump speeds are set in advance in the control mechanism, and these pump speeds are adjusted. By selecting an appropriate rotation speed from among them, a control signal is output from the control mechanism in accordance with the measured concentration range, transmitted to the pump rotation speed controller, and means for controlling the flow rate of the constant flow rate pump of the sample water is used.

According to the ammonium ion measurement method, even when the ammonium ion concentration of the sample water is in a high concentration region showing nonlinearity, it can be seen from the relationship between the ammonium ion concentration and the relative value of the emission intensity. The sample water in the high concentration region is shifted to a low concentration region having linearity by diluting the sample water at an appropriate dilution ratio with a diluting device. Therefore, the dilution is performed after measuring the concentration of ammonium ion (NH ₄ ⁺ ) by the flow injection method. By calculating the measured value by performing an inverse operation according to the magnification, it is possible to obtain an accurate measured value while minimizing a measurement error.

Further, it is possible to change the range of linearity to the ammonium ion concentration of the sample water by utilizing the flow rate characteristics of the sample water, and to accurately measure the water to be measured having an arbitrary concentration with high linearity. be able to.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various specific examples of the method for measuring ammonium ions in water according to the present invention will be described below.

FIG. 1 is a graph showing the relationship between the ammonium ion concentration and the relative value of the output intensity (emission intensity). In the graph, the ammonium ion concentration in the low-concentration region showing linearity with approximately 10 ¹ (ppm) as a boundary. (A) and a high-concentration region (B) showing nonlinearity.

In this embodiment, when the high-concentration region (B) is the region of the sample water to be measured, the sample water in the high-concentration region (B) is appropriately diluted by a diluting device described below. Low concentration area (A)
The main feature of the operation is that the concentration of ammonium ion (NH ₄ ⁺ ) is measured by the above-mentioned flow injection method after the shift to, and the measured value is obtained by performing an inverse calculation according to the dilution ratio. By performing such an operation, the ammonium ion concentration of the sample water in the high-concentration region (B) having no linearity can be measured in the low-concentration region (A) having linearity.

Here, various embodiments of the dilution method and its control method will be described.

[First Embodiment] The dilution method is carried out using a T-type or Y-type connecting part 13 as shown in FIG. That is, in the case of the flow injection method, the sample water 2
It is always passed through at a constant flow rate pump P _1. In the first embodiment by installing constant flow pump P ₅ further one as a diluent, and passed through the diluting water 12 with distilled water by the constant flow rate pump P _5, and the sample water 2 and the diluting water 12 Is mixed and diluted using the T-type or Y-type connection part 13. The operation after such mixing / dilution is performed in the same manner as the conventional operation for measuring the concentration of ammonium ion by the flow injection method.

In the first embodiment, sample water 2 and dilution water 1
Since it is possible to change the dilution ratio of the sample water 2 only by changing the liquid sending amounts set in the constant flow pumps P ₁ and P ₅ for sending the sample water 2, the water quality of the sample water 2 is measured at the time of measuring the ammonium ion concentration. Accordingly, it is easy to change from the concentration region (B) exhibiting non-linearity to the concentration region (A) exhibiting linearity, and it is not necessary to replace the diluting device itself due to a difference in the quality of the sample water 2. Thus, the measurement operation can be easily performed.

[Second Embodiment] The second embodiment relates to a method for measuring ammonium ions having the function of the first embodiment. The constant flow pump P ₁ for the sample water 2 to be measured in the first embodiment is used. in the case of always flow constant flow pump P ₅ dilution water is constant, water change of the sample water to be measured due like seasonal Toka climate and weather, or measured water depending on whether tap water or sewage It is expected that the optimal dilution ratio will not be obtained.

Therefore, in the second embodiment, the main purpose is to obtain a method for realizing an optimal dilution ratio by using the sequencer 10 as a control mechanism and the touch panel 11 as an interface as shown in FIG. .

That is, a plurality of dilution factors a, b, c, and d of the water to be measured are set in advance in the sequencer 10, and the operator selects an appropriate magnification from these dilution factors using the touch panel 11. Input to the sequencer 10. The sequencer 10 controls the flow rate of the dilution factor a, b, c, constant flow pump P ₅ of the constant flow rate pump P ₁ and dilution water sample water conveys a signal corresponding to d in the pump speed controller 14 selected Output a signal.

The signal transmitted to the pump speed controller 14 need not be an analog signal, but may be a contact signal. Then, the control units of the constant flow pumps P ₁ and P ₅ change the amounts of the sample water 2 and the dilution water 12 to be sent in accordance with the contact signals, thereby changing the dilution ratio.

[Third Embodiment] The third embodiment is characterized in that two dispensers (syringes) having a high quantitative property and a dilution mixing tank are used as a dilution method. As described above, the error at the time of the dilution operation becomes a measurement error as it is, so that a high-precision dilution device is required. Therefore, it is customary that the dilution ratio is fixed at a fixed ratio.

The third embodiment will be described with reference to FIG. Reference numeral 15 in the figure denotes a dispenser for quantifying sample water, and its volume is set to (a). Reference numeral 16 denotes a dispenser for diluting water quantification.
And Reference numeral 17 denotes a mixing tank having a volume (a) + a volume (b)
It has a larger volume (c). M ₁ is the dispenser 1
5 is a motor for driving the dispenser 16, and M ₂ is a motor for driving the dispenser 16. SV1 is a three-way solenoid valve for sample water 2, SV1
2 is a three-way solenoid valve for dilution water 12, P ₁ is a constant flow pump of the sample water obtained.

Sample water 2 and dilution water 1 to be injected into the mixing tank 17
If the basic dilution ratio is x when the ratio of 2 is 1: 1, the dilution ratio can be arbitrarily changed by appropriately changing this ratio.

The operation will be described below. In the three-way solenoid valves SV1 and SV2, the dispenser side is "normally open", and the other one of the sample water 2 side (or the dilution water 12 side) is "open". It has become. When the dispensers 15 and 16 perform a quantitative operation, that is, when aspirating into the syringe, the sample water 2 of SV1 and SV2 is used.
Side and the dilution water 12 side are “open”.

The dispenser 1 is driven by driving the motors M ₁ and M _2.
After sucking the sample water 2 and the dilution water 12, the SV1
And SV2 are open on the mixing tank 17 side, and the dispenser 15,
The sample water 2 and the dilution water 12 are injected into the mixing tank 17 by the injection operation 16, that is, by discharging the liquid from the syringe.

By the above operation, the concentration of the sample water becomes (a) / {(a) + (b)}. Further, by operating the diluting water 12 side of the dispenser 16 in the same manner, the sample water is reduced. It is further diluted. These operations are performed by the sequencer 1
Since it can be automatically performed using a control unit such as 0, sample water with various dilution ratios can be obtained by a simple operation.

[Fourth Embodiment] The fourth embodiment is a method for measuring high-concentration ammonium ions using the flow rate characteristics of sample water.

FIG. 5 is a graph showing the flow rate characteristics of the sample water particularly in the ammonium ion measurement in relation to the relative value of the ammonium ion concentration and the output intensity (emission intensity). = 5 has the highest flow rate of the sample water, and Q = 1 has the lowest flow rate.
FIG. 5 shows that when the relative flow rate Q of the sample water is reduced, the ammonium ion exhibits linearity up to a high concentration.

However, reducing the flow rate of the sample water
The relative sensitivity, that is, the output intensity is lowered, and the concentration of ammonium ion at a low concentration in particular cannot be measured, which causes a problem that the lower limit of quantification as an analyzer increases.

Therefore, it is necessary to set the flow rate of the sample water suitable for the measurement concentration range of the sample water, and the method will be described below. The flow injection method shown in FIG. 7 as described above, but taking means for continuously charged into the flow of the drive with a reagent solution of a water sample 2 constant flow pump P ₁ containing ammonium ions, the constant flow pump the driving of the P ₁ can change the flow rate of the water sample by a variable speed.

Therefore, as shown in FIG.
0 and a touch panel 11 as an interface, pump speeds a ′, b ′,
Some c 'and d' are set, and the operator selects a measurement range on the touch panel 11 and inputs it to the sequencer 10. The sequencer 10 pump speed a which is selected ', b', c ', d' conveys a signal corresponding to the pump speed controller 14, a constant flow rate of the pump P ₁ suitable for measuring the concentration range of the sample water Output a signal that controls

The signal transmitted to the pump speed controller 14 does not need to be an analog signal, but may be a contact signal. The control unit of the constant flow pump P ₁ changes the feed volume of the water sample in response to the contact signal, it is possible to change the flow rate of the water sample as a result.

[0048]

As described in detail above, according to the method for measuring ammonium ions in water according to the present invention, the non-linearity of the ammonium ion concentration in the sample water is determined from the relationship between the ammonium ion concentration and the relative value of the emission intensity. Even when in the high concentration region indicating, by diluting the sample water at an appropriate dilution factor, the concentration of ammonium ions is measured by a flow injection method after shifting to a low concentration region having linearity, Since the measured value is obtained by back calculation along the dilution ratio, a fairly accurate measured value can be obtained by minimizing a measurement error particularly when the ammonium ion concentration is in a high concentration region.

The present invention can be applied not only to the concentration of ammonium ions dissolved in the raw water for drinking water but also to the operation in sewage, so that the effect of reducing the measurement error particularly in the high concentration region is great.

As the means for diluting the sample water, any of the methods described in claims 2 to 4 can be adopted, and the method can be selected and diluted according to the sample water. Further, since the linearity range can be changed to the ammonium ion concentration of the sample water using the flow rate characteristics of the sample water as described in claim 5, the water to be measured having an arbitrary concentration can be increased. It can be measured accurately with linearity.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the ammonium ion concentration and the relative value of output intensity (emission intensity).

FIG. 2 is a schematic diagram showing a first embodiment of a method for diluting sample water employed in the present invention.

FIG. 3 is a schematic diagram showing a second embodiment of a method for diluting a sample water.

FIG. 4 is a schematic diagram showing a third embodiment of a method for diluting sample water.

FIG. 5 is a graph showing flow rate characteristics of sample water in ammonium ion measurement.

FIG. 6 is a schematic diagram showing a fourth embodiment of a method for diluting a sample water.

FIG. 7 is a schematic diagram showing an example of an apparatus for measuring ammonium ions by a flow injection method.

FIG. 8 is a schematic diagram showing an example of control in the measuring device of FIG. 7;

FIG. 9 is a graph showing a relationship between a relative value of ammonium ion concentration and a relative value of output intensity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reaction reagent 2 ... Sample water 3 ... Air 4 ... Mixing coil 5 ... Vaporization separator 6 ... Heating oxidation furnace 7 ... Waste liquid 8 ... Chemiluminescence detector 9 ... Ozone generator 10 ... Sequencer 11 ... Touch panel 12 ... Dilution water 13 ... Connecting parts 14 ... Pump rotation speed controller 15,16 ... Dispenser 17 ... Mixing tank 21 ... Flow tube

Claims (5)

[Claims] 1. A gas separated and separated from a liquid phase by a vaporization separator while flowing a sample water containing ammonium ions into the reaction reagent while flowing the reaction reagent down in the flow channel capillary. After the components are converted to nitric oxide in a heating and oxidizing furnace, the concentration of ammonium ions in water by the flow injection method, in which the chemiluminescence intensity is detected by a detector and the amount of ammonium ions in the gas phase is determined, The sample water in the region is shifted to the low concentration region by diluting the sample water at the optimal dilution ratio with a diluting device, and then measuring the ammonium ion concentration by the flow injection method, and performing a back calculation by the dilution ratio to obtain a measured value. A method for measuring ammonium ions in water. 2. The ammonium ion in water according to claim 1, wherein the dilution method comprises mixing and diluting sample water and dilution water fed by a constant flow pump using a T-type or Y-type connection part. Measuring method. 3. A pump rotation speed controller and a control mechanism are provided in each of said constant flow pumps, and a plurality of dilution ratios of water to be measured are set in advance in said control mechanisms. 2. The method according to claim 1, wherein a selection signal is output from the control mechanism to the pump rotational speed controller by selecting a magnification to control the flow rate of each of the constant flow pumps. For measuring ammonium ion in water. 4. A dispenser for quantifying sample water, a dispenser for quantifying dilution water, and a mixing tank are prepared, and a suction / discharge operation of the sample water by the dispenser for quantifying sample water and dilution are performed. 2. The method for measuring ammonium ions in water according to claim 1, wherein the ratio of the sample water to the dilution water is appropriately changed and injected into the mixing tank by a suction / discharge operation of the dilution water by a water dispenser. . 5. A constant flow pump for sample water, comprising a pump rotation speed controller and a control mechanism, wherein a plurality of pump rotation speeds are set in advance in the control mechanism, and an appropriate one of these pump rotation speeds is selected. 2. The underwater water according to claim 1, wherein by selecting the number of revolutions, the control mechanism outputs a setting signal corresponding to the measured concentration range and transmits the setting signal to the pump revolution number controller to control the flow rate of the constant flow rate pump of the sample water. Ammonium ion measurement method.