JP5904435B2 - Heavy metal ion measuring instrument - Google Patents

Description

The present invention relates to a heavy metal ion measuring device using an analytical method for colorimetrically measuring the presence or concentration of a heavy metal of interest using a color reaction from drinking water possibly contaminated with heavy metals such as arsenic . The present invention relates to a heavy metal ion measuring instrument that is portable and can be analyzed by a simple operation.

    According to the water quality standards of the Ministry of Health and Welfare (Non-Patent Document 1), the allowable amount of harmful heavy metals dissolved in drinkable water depends on the type of heavy metal (Cd <0.01, Pb <0.01, Cr (6 +) <0.05, Hg <0.0005, As <0.01 mg / l).

  If any of these substances exceeds this reference value, it will be heavy metal contaminated water, but usually the contaminated water will not be highly concentrated unless its value is much higher than the reference value. Tasteless and odorless. In addition, when these heavy metals are dissolved as ions in water, in principle, the ions are colored to absorb light of a specific wavelength, but the color tone varies depending on the substance, The concentration looks not only different from the ion concentration but also depending on the thickness of the observation water. In particular, it is considered difficult to detect contamination by the sense of the human eye when the observation water is thin (for example, about a full glass thickness) in a very small concentration range as described above. In the detection, the presence of advanced analytical instruments and trained operators is an indispensable element.

  However, these methods are difficult to apply in times of disaster such as earthquakes, tsunamis, floods, etc., or in ordinary households that use well water or spring water, and do not require special specialized knowledge and technology. There is a strong demand for the development of small detection / analysis instruments that are portable and can be detected on the spot.

  From the viewpoint of in-situ detection, there are a method using a portable energy dispersive X-ray fluorescence spectrometer (Non-Patent Document 2), an ion analysis method using an ion-selective electrode (Patent Document 1), and the like. Although it has been developed, in any case, it requires specialized knowledge and operation technology in that field, and it is difficult to say that it is a technology that ordinary people can use on a daily basis at home.

  On the other hand, the inventors have developed a selective adsorbent of heavy metal ions, and during the adsorption, the color change due to the color reaction proceeds along with the adsorption of the heavy metal ions, and from the hue change, It was found that the ion concentration can be accurately quantified (Non-patent Document 3).

  By using such an adsorbent, the concentration of heavy metal ions can be easily measured by a colorimetric test without using a special analytical instrument. Therefore, by applying these characteristics, it is possible to configure a portable detector that can easily detect in situ heavy metal ions.

JP 9-89832 A

Environmental Agency Notification No.59 (1974) Kyushu University Central Analysis Center Report No. 26 (2008) Nanomaterials for Life Sciences Vol 2: NanostructuredOxides. 2009.

    However, even when heavy metal ions are detected by the above method, it is necessary to adjust the pH of the water to be tested and add / mix the reaction aid (for example, using the selective adsorbent of Non-Patent Document 3). In the case of arsenic detection, it is required to make the pH acidic to 7 or less), and it is also a fact that it is quite difficult for an inexperienced person to adjust them according to the amount of water to be tested.

The object of the present invention is to provide a small and lightweight heavy metal ion measuring device capable of measuring heavy metal ions quickly and easily at an arbitrary place. The present invention provides a heavy metal ion measuring apparatus employing a batch system capable of continuously performing all processes from collection to weighing, blending, and color reaction in the same container .

  As a device configuration for achieving the above-mentioned object, a part or the whole of the detection tube is made of a colorless and transparent material (for example, glass), and its size can be operated with one hand (generally: a diameter of 10 cm or less). , A length of 50 cm or less, and a weight of 5 kg or less), and a colorless and transparent small container (hereinafter referred to as a water receiving container 2) in which a selective adsorbent (solid sensor) exhibiting a color reaction is disposed. The target heavy metal ions are detected by the change in hue. At that time, the collected amount of water to be tested is made constant, and an adjustment liquid (used for pH adjustment and auxiliary component addition) corresponding to the collected amount is prepared in advance as a cartridge (hereinafter referred to as adjustment liquid container 3). By mixing these two contents, an aqueous solution condition suitable for the color environment of the selective adsorbent is established in the detection tube. The presence or absence of heavy metal ions or their concentration is determined by comparing the hue change obtained by these operations with a reference color scale.

  To make the amount of water to be tested constant, place a water receiving container 2 of a certain volume inside the detection tube, and once the test water is filled in the small container until the water to be tested is filled, Drain the water to be tested. Examples of introducing test water into the detection tube include suction with a dropper or cylinder, immersion of the test water into the detection tube with an air escape at the top, or pouring the test water from the top.

  The bottom of the water receiving container 2 can be made of any material as long as it can be easily broken by an external operation during mixing with the adjustment liquid described later and does not react with the adjustment liquid (for example, a plastic film).

  Separately from the water receiving container 2, an adjustment liquid container 3 filled with the adjustment liquid is disposed in the detection tube. A part of the adjustment liquid container 3 has a partition wall that can be easily broken like the bottom of the water receiving container 2. In addition, the material of this partition should just have the characteristic similar to the bottom face of the said water receiving container 2. FIG. When the water to be tested is filled in the water receiving container 2 and excessive water is discharged, the bottom of the water receiving container 2 and the partition wall of the adjustment liquid container 3 are destroyed by external operation, and the adjustment liquid and the water to be tested are removed. Mix. When mixing the adjustment liquid and the water to be tested, a small container having a volume larger than the combined volume of the water receiving container 2 and the adjustment liquid container 3 may be disposed in the detection tube. A partition wall is provided, and the partition wall for destruction is arranged to be the bottom surface of the water receiving container 2 (that is, the bottom surface of the water receiving container 2 is shared with the partition wall for breaking the adjustment liquid container 3). The water receiving container 2 and the adjustment liquid container 3 can be connected by destruction. For breaking the partition wall of the adjustment liquid container 3, there is a method of knocking the needle from above. At that time, a thing that plays the role of the lid of the water receiving container 2 is provided in the needle shaft portion, and the water receiving container 2 is covered simultaneously with the breakage of the partition wall so that the bottom of the water receiving container 2 and the adjustment liquid container 3 are combined. The small container can be closed and the liquid can be easily homogenized by shaking up and down.

The color-adsorbing individual body weight metal ion selective adsorbent (hereinafter referred to as sensor material 5) may be arranged at either the bottom of the water receiving container 2 or the adjustment liquid container 3 as long as the constant volume condition is not impaired. If it is placed in the water receiving container 2, if the test water is not contaminated, it can be reused for measurement simply by replacing the adjusting liquid container 3 containing the adjusting liquid.
As described above, the measuring instrument of the present invention is constructed in a detection tube that can be regarded as a kind of closed system for the functions required for various processes from the sampling of the water to be tested to mixing with the adjustment liquid and the color reaction of the sensor material. By adopting the batch method, the operation from the outside of the detector at the time of measurement can be performed by collecting the test water by dropper suction, sealing the receiving container by pushing the needle and integrating the adjustment liquid container, and testing by shaking the detector. This is a very simple operation method of mixing water and adjustment liquid, and can be operated with one hand.

With the above-mentioned portable heavy metal ion detector, even those who have no specialized knowledge or skills in chemistry can easily know whether or not the target water is contaminated with harmful heavy metals on the spot that requires safe drinking water. It is possible.
As color selective adsorbents used in this method, those targeting harmful metals such as As, Cd, and Hg have been developed. If developed, this method can be applied to the detection of harmful organic compounds as well as other metals.

An example (dropper type) of the basic structure of the detection tube is shown in FIG. Here, 1 is a detection tube, 2 is a water receiving container, 3 is an adjustment liquid container, 4 is an adjustment liquid container diaphragm that separates the water receiving container 2 and the adjustment liquid container 3, and 5 is a color sensor that selectively adsorbs heavy metal ions. Material, 6 for adjusting liquid container diaphragm breaking pin, 7 for dropper for collecting test water, 8 for test water sampling port, 9 for measuring lid for receiving container 2 attached to the diaphragm breaking pin, and 10 for breaking pin A push bar 11 for driving 6 and a color scale 11 for comparing the color development state of the sensor material 5. Here, when determining the presence or absence of heavy metal contamination, it is not necessary to incorporate a color scale 11 (see FIG. 2) that can determine a wide range of contamination concentrations, and color objects around the permissible concentration of heavy metal ions to be measured. Need only be arranged as a color scale. As an example, FIG. 2 shows the relationship between the As ion concentration and the hue change of the sensor material when the As ion colorimetric selective adsorbent is used as the sensor material. It should be noted that here, for the range of As ion concentration: 0 to 50 ppb, color No. 1 to 5 are shown separately.

The basic structure of the detection tube will be described taking the dropper type of FIG. 1 as an example.
In the detection tube, there are two containers, a water receiving container 2 and an adjustment liquid container 3, which are in contact with an adjustment liquid container diaphragm at the upper part of the adjustment liquid container 3. The water receiving container 2 has a cylindrical shape having no bottom surface, the side surface thereof is closely attached to the upper part of the adjustment liquid container 3 by screwing or rubbing, and the bottom surface is shared with the adjustment liquid container diaphragm 4. The diaphragm breaking process at the time of measurement as described later can be performed in one stage.

Further, there is a push rod 10 inside the detection tube, and after the water receiving container 2 is filled with the liquid to be tested, the adjuster container diaphragm 4 can be broken by an act such as pushing the rod from the outside by an examiner. . At this time, the measurement lid 9 attached to the push-in rod is in close contact with the water receiving container 2 so that the space formed by the water receiving container 2 and the adjustment liquid container 3 is sealed, and the solution is not removed during shaking. External leakage is prevented. The sensor material 5 which is a color-selective adsorbent is in the water receiving container 2, and after pressing the push-in rod, it reacts with the uniform solution by gently shaking the entire detection tube, and the target heavy metal ions If can be detected, a color reaction is shown. In order to see the color change due to this reaction, the detector tube and the water receiving container should be transparent or have a structure where the necessary parts can be seen. If a reference color object (color scale 11) indicating the coloration reactivity of the selective adsorbent is placed in a part of the detection tube, it is possible to easily determine the presence or absence of contamination and to prepare separately from the detection tube The contamination concentration can be determined by comparing with the more detailed color scale.
In this measurement operation, the test water is sucked with a dropper to fill the water-receiving container 2 with the liquid to be tested, and then the push-in rod 10 is pushed downward through the dropper part (the measurement Sealing of the water receiving container 2 by the lid 9, destruction of the adjustment liquid container diaphragm 4 and integration of the water receiving container 2 and the adjustment liquid container 3 occur). Next, the detection tube is shaken up and down, the test water and the adjustment liquid are mixed, and after a predetermined time has elapsed, the hue change of the sensor material 5 is checked.
In this way, the external measurement operation required for this detector is as simple as sucking water under test with a dropper, pushing the push rod through the dropper, shaking the detection tube, and determining the sensor material hue. The operation does not require any special knowledge or skills.

An embodiment of a detector targeting arsenic as a toxic heavy metal will be described. As a selective adsorbent for coloring arsenic, an arsenic (V) ion optical sensor based on TiO ₂ nanomaterials described in Non-Patent Document 3 (arsenic ion adsorption element and As ion concentration detection method in water using the same) is used. used.
The detection tube used in this test is of the dropper type with an outer diameter of about 12 mm and a length of about 100 mm. The outer diameter of the water receiving container and the adjustment liquid container are both about 8 mm, and the total inner volume of both containers is about 0. .5 ml. The color scale used for the measurement is shown in FIG.

  Table 1 shows the results obtained by visual inspection of the colored state when the arsenic (V) ion concentration of the test solution was variously changed.

Here, in view of the fact that one of the objects of the present invention can be easily measured by the general public, this visual inspection of the color development state (comparison between the color development state and the color scale) 3 The name was repeated three times for each test condition (arsenic (V) ion concentration).

  As can be seen from these results, by using the measuring method and measuring instrument of the present invention, it is very easy to measure not only the presence or absence of harmful heavy metal ions but also the concentration of ordinary people who do not have specialized knowledge. It can be done.

  The present invention is a small portable detector developed for the purpose of in-situ detection of heavy metal ions harmful to the human body contained in drinking water, and its features do not require special accessory equipment or equipment for measurement. In addition, the measurement operation does not require expertise. By using the present invention, it is considered that not only can the development and promotion of water resources, which are a global issue, be promoted, but it can also greatly contribute to the improvement of the safety of drinking water in remote areas and disaster areas. .

DESCRIPTION OF SYMBOLS 1 Detector 2 Water receiving container 3 Adjustment liquid container 4 Adjustment liquid container diaphragm 5 Sensor material 6 Breaking pin 7 Dropper 8 Water sampling port 9 Measuring lid 10 Push rod 11 Color scale

Claims (3)

In the measurement of heavy metal ions in water, it is a heavy metal ion measuring instrument that uses the change in hue using a color reactive selective adsorbent ,
In a heavy metal ion measuring device that is a batch system that can perform the entire process from collection of water to be tested to weighing, blending, and color reaction in the same container ,
A water receiving container (2) filled with the test water;
An adjustment liquid container (3) having an adjustment liquid in an amount commensurate with the amount of water to be tested,
An adjustment liquid container diaphragm (4) located at the top of the adjustment liquid container (3) and shared with the bottom surface of the water receiving container (2);
A color-selective adsorbent (5) provided in the water-receiving container (2);
Means (6, 10) for breaking the adjustment liquid container diaphragm (4) at the time of measurement;
A heavy metal ion measuring instrument comprising: 2. The heavy metal ion measuring device according to claim 1, wherein the means for breaking the diaphragm includes a push-in rod (10) and a pin (6) for adjusting liquid container diaphragm breaking.   The heavy metal ion measuring instrument according to claim 1 or 2, further comprising a measurement lid (9) attached to the push rod (10),
  Heavy metal, characterized in that when the adjustment liquid container diaphragm (4) is broken by the push rod (10), the measurement lid (9) is in close contact with the water receiving container (2) Ion meter.