JP2001228139A - Calibration method for water quality measuring instrument and calibrating mixed standard solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a calibration method for water quality measuring instrument capable of easily and precisely calibrating a water quality measuring instrument equipped with a plurality of sensors at a low cost. SOLUTION: This calibration method for the water quality measuring instrument equipped with a plurality of sensors 7 and 8 for measurement of water quality comprises performing the two-point calibration including zero-point calibration of the sensors 7 and 8 by use of two kinds of mixed standard solutions A and B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calibrating a water quality measuring apparatus and a mixed standard solution for calibration suitable for use in water quality surveys of rivers, lakes, marshes, seas, etc., and water quality management in aquaculture and hydroponics.

[0002]

2. Description of the Related Art Water quality can be measured in a number of items such as dissolved oxygen, conductivity, oxidation-reduction potential, hydrogen ions, various ions other than hydrogen ions (such as chloride ions and fluoride ions), and turbidity. When measuring these items, the water temperature and the water depth at the time of the measurement, and further, the salt concentration and the density calculated based on the conductivity are also measured.

[0003] Performing each of these measurements with a dedicated measuring device complicates the operation in addition to the cost problem. For example, hydrogen ions, which are basic indicators of water quality, turbidity, A water quality measuring device capable of simultaneously measuring dissolved oxygen content and storing the measured value is used.

[0004]

However, in the calibration of the water quality measuring device having the above-described configuration, for example, when two-point calibration is performed for all sensors, conventionally, a standard solution for calibration is provided for each sensor. , Two types were prepared, and two-point calibration of each sensor was performed sequentially. Therefore, it takes a considerable amount of time and labor to calibrate all the sensors, and there is a problem that the cost for performing the calibration increases because a large number of standard solutions need to be prepared.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems, and has as its object to provide a water quality measuring apparatus having a plurality of sensors, which can perform simple, low-cost, high-precision calibration. An object of the present invention is to provide a method for calibrating an apparatus and a mixed standard solution for calibration.

[0006]

In order to achieve the above object, a method of calibrating a water quality measuring device according to the present invention is a method of calibrating a water quality measuring device provided with a plurality of sensors for measuring water quality. Two-point calibration, including zero-point calibration of the sensor
This is performed using two types of mixed standard solutions (claim 1).

[0007] As a first standard mixed solution, pH
A mixed standard solution composed of 4.01 phthalate buffer may be used (claim 2). Further, as a second standard mixed solution, 2 mol / L sodium sulfite and 7
mmol / L hydrazinium sulfate and 70mmo
1 / L hexamethylenetetramine and 0.025 mm
A mixed standard solution containing ol / L potassium dihydrogen phosphate as a component may be used (claim 3).

A method for calibrating a water quality measuring device according to the present invention is a method for calibrating a water quality measuring device having a plurality of sensors for measuring water quality, the method comprising a three-point calibration including a zero point calibration for the plurality of sensors. In the case where the reaction is performed using three types of mixed standard solutions (Claim 4), p
A mixed standard solution consisting of H4.01 phthalate buffer may be used (claim 5), and as a second mixed standard solution, 2 mol / L sodium sulfite and 7 mm
ol / L hydrazinium sulfate and 70 mmol / L
Of hexamethylenetetramine and 0.025 mmol
/ L potassium dihydrogen phosphate may be used as a component (Claim 6). Further, as a third mixed standard solution, 0.7 mmol / L hydrazinium sulfate, A mixed standard solution containing 7 mmol / L hexamethylenetetramine and 0.01 mmol / L sodium tetraborate as components may be used (Claim 7).

Further, the plurality of sensors may include at least sensors for measuring pH, dissolved oxygen and turbidity.

According to the above configuration, in a water quality measuring device having a plurality of sensors, a water quality measuring device capable of performing two-point calibration or three-point calibration including zero-point calibration easily, at low cost, and with high accuracy. A calibration method can be provided.

The calibration mixed standard solution of the water quality measuring device of the present invention is a calibration mixed standard solution used for a water quality measuring device having a plurality of sensors for measuring water quality, and comprises 2 mol / L sodium sulfite and The composition contains 7 mmol / L of hydrazinium sulfate, 70 mmol / L of hexamethylenetetramine, and 0.025 mmol / L of potassium dihydrogen phosphate (claim 9).

Further, the calibration standard solution of the water quality measurement device of the present invention is a calibration standard solution used for a water quality measurement device having a plurality of sensors for water quality measurement, and is 0.7 m in length.
mol / L hydrazinium sulfate and 7 mmol /
L of hexamethylenetetramine and 0.01 mmol
/ L sodium tetraborate may be contained in the component (claim 10).

According to the above configuration, in a water quality measuring device provided with a plurality of sensors, a water quality measuring device capable of performing two-point calibration including zero-point calibration and three-point calibration easily and at low cost and with high accuracy is provided. A calibration standard solution can be provided.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view schematically showing a configuration of a water quality measuring device D for performing a method for calibrating a water quality measuring device according to a first embodiment of the present invention. PH, Dissolved Oxygen concentration, which are basic indicators of water quality,
A water quality measuring device D for measuring water quality and turbidity (Turbidity) includes an immersion type sensor unit 1 having a plurality of sensors for measuring water quality, and a waterproof cable 2 attached to the sensor unit 1.
And the instrument body 3 electrically connected through the

At the lower end 4 of the sensor section 1, a pH sensor 7 composed of a glass electrode 5 for pH measurement and a reference electrode 6, a turbidity sensor (not shown), and a dissolved oxygen concentration are measured. And a DO sensor 8 are provided. In addition, the glass electrode 5, the comparison electrode 6, and the DO sensor 8
In general, the cartridge type is used in consideration of deterioration with use or unexpected damage, and replacement is easy.

The data detected by these measuring sensors is:
The sensor unit 1 is sent to the instrument main body 3 through the cable 2 capable of holding the sensor unit 1 in a suspended state, and data processing is performed in the instrument main body 3.

A watertight case 9 having a pressure-resistant structure is provided above the sensor unit 1.
Inside, a power supply (not shown), an arithmetic unit (not shown) having a memory function unit, and a data logger (not shown) for recording the measured data of water quality and the like in time series are provided. Is provided.

The instrument body 3 includes a power supply key 11, a function key 1 and a display unit 10 for displaying the measurement data and the like.
2, a measurement start / end key 13, a calibration key 14, a select key 15, up / down keys 16 and 17, and the like.

The water quality measurement by the water quality measurement device D having the above configuration is performed in a state where the plurality of types of measurement sensors are immersed in, for example, seawater. That is, the water quality measurement is performed by holding the cable 2 and hanging the sensor unit 1 in seawater.

When the sensor unit 1 is submerged in this way, measurement data based on outputs from the plurality of types of measurement sensors is stored in the memory function unit, and the measured values are displayed on the display unit 10. You.

In this water quality measuring device D, the measurement data is logged to the data logger by arbitrarily operating the data fetching switch of the data logger with the function key 12, and the pH, turbidity and dissolved oxygen concentration are measured. The water quality measurement can be performed with high accuracy, and the measured data can be printed by inputting the information of the data logger to a printer (not shown).

Reference numeral 18 denotes a cylindrical protection tube detachably provided to a lower portion of the sensor portion 1 for protecting the plurality of types of measurement sensors provided at a lower end portion of the sensor portion 1. Yes, it is possible to prevent the measurement sensor from being damaged due to an impact at the time of measurement. In the case of calibration or storage, it also serves as a stand.

Next, a method of calibrating the water quality measuring device will be described. The calibration method of the water quality measurement device according to the first embodiment of the present invention, the water quality measurement device D having the above configuration,
This is a calibration method for performing two-point calibration including zero-point calibration. In order to perform two-point calibration of the water quality measuring device D, two types of mixed standard solutions A and B are used. In addition, a mixed standard solution composed of a phthalate buffer solution having a pH of 4.01 was used as the first standard mixed solution A, and 2 m of the second standard mixed solution B was used.
A mixed standard solution composed of ol / L sodium sulfite, 7 mmol / L hydrazinium sulfate, 70 mmol / L hexamethylenetetramine, and 0.025 mmol / L potassium dihydrogen phosphate was used. Here, Table 1 shows the values of pH, turbidity, and dissolved oxygen concentration (B only) of the mixed standard solutions A and B.

[0024]

[Table 1]

In Table 1, the value of the dissolved oxygen concentration described in the column of the mixed standard solution A is not the value of the mixed standard solution A, but the value of the (dissolved) oxygen concentration in the atmosphere.

A water quality measuring device D using the mixed standard solution A
To perform the first point calibration, as shown in FIG.
A mixed standard solution A in which a pH sensor 7 and a turbidity sensor provided at the lower end 4 of the water quality measuring device D are filled in a container 19.
The DO sensor 8 need only be immersed in the mixed standard solution A.

Mixed standard solution A used for the first point calibration
Since turbidity is 0, zero point calibration of the turbidity sensor can be performed. In addition, in the first point calibration, the DO sensor 8 is configured not to be immersed in the mixed standard solution A.
Is left in the atmosphere and is dissolved in the atmosphere.
This indicates the value of the oxygen concentration (8.52 mg / l). That is, for the DO sensor 8, normal fixed point calibration, not zero point calibration, is performed. The pH sensor 7
Also, the normal fixed-point calibration other than the zero-point calibration is performed.

In the first calibration, the dissolved oxygen concentration of the mixed standard solution A is not measured, so that the dissolved oxygen concentration of the mixed standard solution A may be any value.

Water quality measuring device D using the mixed standard solution B
To perform the second point calibration, as shown in FIG.
A pH sensor 7 provided at the lower end 4 of the water quality measuring device D,
It is only necessary to immerse the turbidity sensor and the DO sensor 8 in the mixed standard solution B filled in the container 19.

The mixed standard solution B used for the second point calibration
Has a pH value of 6.86 and is a value indicating neutrality, p
Since it is close to H7.00, it is possible to perform calibration corresponding to the zero point calibration of a general sensor for the pH sensor 7. Further, since the entirety of the DO sensor 8 is immersed in the mixed standard solution B having zero dissolved oxygen, the zero point calibration of the DO sensor 8 can be performed. Note that, for the turbidity sensor, normal fixed-point calibration, not zero-point calibration, is performed.

According to the method of calibrating the water quality measuring device having the above-described configuration, the two-point calibration including the zero point calibration for the water quality measuring device D can be performed by only two simple calibrations using two kinds of mixed standard solutions. Can be performed with a high degree of accuracy, and the user can purchase only two types of mixed standard solutions, so that the cost for calibration, such as the purchase cost, can be reduced. Since only the types are used, the space required for storing the mixed standard solution and the like can be reduced.

In the method of calibrating the water quality measuring device having the above-mentioned configuration, in the first calibration, the normal fixed point calibration which is not the zero point calibration is performed by not immersing the DO sensor 8 in the mixed standard solution A. , In the second calibration, D
Although the O sensor 8 is immersed in the mixed standard solution B to perform zero point calibration, it is not limited to such a configuration.
In the first point calibration, the DO sensor 8 is immersed in the mixed standard solution A to perform zero point calibration, and in the second point calibration,
Ordinary fixed point calibration other than zero point calibration may be performed without immersing the DO sensor 8 in the mixed standard solution B. In this case, the dissolved oxygen concentration of the mixed standard solution A is set to zero.

In the method of calibrating a water quality measuring device having the above configuration, only the pH sensor 7, the DO sensor 8, and the turbidity sensor are calibrated. Is not intended only for these three measurement sensors, for example, the water quality measurement device D
If the sensor has a sensor such as a conductivity sensor or a temperature sensor in addition to the above measurement sensor, two-point calibration including zero-point calibration can be easily performed for such a measurement sensor by performing two calibrations. It can be performed at low cost.

In the method for calibrating a water quality measuring device having the above-mentioned configuration, the mixed standard solution for calibrating the water quality measuring device D is not limited to the mixed standard solutions A and B, and the same effect can be obtained. If possible, a material having a different composition or the like may be used.

FIG. 1 and FIGS. 2A and 2B are views showing a method of calibrating a water quality measuring apparatus according to a second embodiment of the present invention. Next, a method for calibrating the water quality measuring device according to the second embodiment of the present invention will be described. Note that members having the same structures as those shown in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The method for calibrating the water quality measuring device of the second embodiment is for performing three-point calibration including zero-point calibration for the water quality measuring device D. The description is omitted because it is the same as the calibration method of the water quality measuring device of the embodiment.

In the method of calibrating the water quality measuring device of the second embodiment, the mixed standard solution C used for the third point calibration is 0.7 m
mol / L hydrazinium sulfate and 7 mmol /
L of hexamethylenetetramine and 0.01 mmol
/ L sodium tetraborate. Here, Table 2 shows the values of the pH, turbidity, and dissolved oxygen concentration of the mixed standard solution C.

[0037]

[Table 2]

A water quality measuring device D using the mixed standard solution C
In order to perform the third point calibration, as shown in FIG.
A pH sensor 7 provided at the lower end 4 of the water quality measuring device D,
It is only necessary to immerse the turbidity sensor and the DO sensor 8 in the mixed standard solution C filled in the container 19.

In the third calibration, the pH sensor 7, D
For the O sensor 8 and the turbidity sensor, normal fixed point calibration, not zero point calibration, is performed.

According to the method for calibrating the water quality measuring device having the above-described configuration, the three-point calibration including the zero point calibration for the water quality measuring device D can be performed by only three simple calibrations using three types of mixed standard solutions. In addition, since three types of mixed standard solutions need to be purchased on the user side, calibration costs such as purchase costs can be reduced, and further, only three types of mixed standard solutions can be used. Therefore, the space required for storing the mixed standard solution can be reduced.

In the method of calibrating a water quality measuring device having the above configuration, only the pH sensor 7, the DO sensor 8, and the turbidity sensor are calibrated. Is not intended only for these three measurement sensors, for example, the water quality measurement device D
If the sensor has a sensor such as a conductivity sensor or a temperature sensor in addition to the above-mentioned measurement sensor, three-point calibration including zero-point calibration can be easily performed for such a measurement sensor by performing three calibrations. It can be performed at low cost.

Further, in the method for calibrating a water quality measuring device having the above configuration, the third standard mixed solution for calibrating the water quality measuring device D is not limited to the mixed standard solution C, and the same effect can be obtained. If they can be obtained, those having different compositions and the like may be used.

[0043]

As described above, according to the present invention having the above-described structure, in a water quality measuring device having a plurality of sensors, water quality measurement can be performed easily, at low cost and with high accuracy. An apparatus calibration method and a calibration standard solution can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a configuration of a water quality measuring device in a method for calibrating a water quality measuring device according to a first embodiment and a second embodiment of the present invention.

FIG. 2A is an explanatory view schematically showing a first point calibration method in the above two embodiments, and FIG. 2B is a diagram showing a second point calibration method and a second point calibration method in the two embodiments. It is explanatory drawing which shows the calibration method of the 3rd point in an Example roughly.

[Explanation of symbols]

7 ... pH sensor, 8 ... DO sensor, A ... mixed standard solution, B
... mixed standard solution, D ... water quality measurement device.

Claims (10)

[Claims] 1. A method for calibrating a water quality measuring device including a plurality of sensors for measuring water quality, wherein two-point calibration including zero-point calibration of the plurality of sensors is performed using two types of mixed standard solutions. A method for calibrating a water quality measuring device, comprising: 2. A first standard mixed standard solution having a pH of 4.0
The method for calibrating a water quality measurement device according to claim 1, wherein a mixed standard solution comprising the phthalate buffer is used. 3. A mixture of 2 mol / mol as a second standard mixed solution.
A mixed standard solution containing, as components, L sodium sulfite, 7 mmol / L hydrazinium sulfate, 70 mmol / L hexamethylenetetramine, and 0.025 mmol / L potassium dihydrogen phosphate. 3. The method for calibrating a water quality measuring device according to 1 or 2. 4. A method for calibrating a water quality measurement device having a plurality of sensors for measuring water quality, wherein three-point calibration including zero-point calibration of the plurality of sensors is performed using three types of mixed standard solutions. A method for calibrating a water quality measuring device, comprising: 5. The method according to claim 1, wherein the first standard mixed solution has a pH of 4.0.
5. The method for calibrating a water quality measuring device according to claim 4, wherein a mixed standard solution comprising one phthalate buffer is used. 6. A second standard mixed solution comprising 2 mol / mol
A mixed standard solution containing, as components, L sodium sulfite, 7 mmol / L hydrazinium sulfate, 70 mmol / L hexamethylenetetramine, and 0.025 mmol / L potassium dihydrogen phosphate. 6. The method for calibrating a water quality measuring device according to 4 or 5. 7. A third standard mixed solution comprising 0.7 m
mol / L hydrazinium sulfate and 7 mmol / L
Hexamethylenetetramine and 0.01 mmol / L
The method for calibrating a water quality measuring device according to any one of claims 4 to 6, wherein a mixed standard solution containing sodium tetraborate as a component is used. 8. The method according to claim 8, wherein the plurality of sensors include at least p.
The method for calibrating a water quality measuring device according to any one of claims 1 to 7, further comprising a sensor for measuring H, dissolved oxygen, and turbidity. 9. A mixed standard solution for calibration used in a water quality measurement device provided with a plurality of sensors for water quality measurement,
ol / L sodium sulfite, 7 mmol / L hydrazinium sulfate, 70 mmol / L hexamethylenetetramine, and 0.025 mmol / L potassium dihydrogen phosphate as components. Mixed standard solution for calibration of water quality measurement equipment. 10. A calibration mixed standard solution used in a water quality measurement device having a plurality of sensors for water quality measurement,
0.7 mmol / L hydrazinium sulfate and 7 m
mol / L hexamethylenetetramine and 0.01 m
A mixed standard solution for calibration of a water quality measuring device, comprising mol / L of sodium tetraborate as a component.