CN118311024A - Method and test paper for rapidly detecting fluoride ions in water - Google Patents
Method and test paper for rapidly detecting fluoride ions in water Download PDFInfo
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- -1 fluoride ions Chemical class 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 23
- 239000000243 solution Substances 0.000 claims abstract description 53
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims abstract description 31
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- 239000012086 standard solution Substances 0.000 claims description 8
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- 238000004737 colorimetric analysis Methods 0.000 abstract description 9
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- 238000011161 development Methods 0.000 description 33
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- 229910021641 deionized water Inorganic materials 0.000 description 6
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- 210000000988 bone and bone Anatomy 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 4
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- 239000011575 calcium Substances 0.000 description 4
- 239000003651 drinking water Substances 0.000 description 4
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- 238000010561 standard procedure Methods 0.000 description 2
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- RGCKGOZRHPZPFP-UHFFFAOYSA-N Alizarin Natural products C1=CC=C2C(=O)C3=C(O)C(O)=CC=C3C(=O)C2=C1 RGCKGOZRHPZPFP-UHFFFAOYSA-N 0.000 description 1
- 208000020084 Bone disease Diseases 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
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- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
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- 208000008558 Osteophyte Diseases 0.000 description 1
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- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 1
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- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Abstract
The invention discloses a method and test paper for rapidly detecting fluoride ions in water, which comprises the following steps: the test paper carrying the color-developing agent is obtained by immersing the test paper in a color-developing agent solution for a period of time and then drying, wherein the color-developing agent solution is prepared by mixing 3-methyl amine-alizarin diacetic acid solution, acetic acid-sodium acetate buffer solution, acetylacetone and lanthanum salt solution according to the volume ratio of 3:1:3:3, and then adding polyethylene glycol accounting for 0.5-1 wt% into the obtained mixed solution. The fluorine ion test paper prepared by the invention can gradually and uniformly change color within the range of 0.5ppm to 100ppm according to different fluorine contents, and the detection range is far beyond the existing colorimetric method.
Description
Technical Field
The invention belongs to the technical field of chemical analysis, and relates to a detection method for determining the content of fluoride ions in water by using a visual colorimetry, test paper and application thereof.
Background
Fluorine is an indispensable trace element for life activities of human bodies, the main source route of fluorine in human bodies is drinking water, low-concentration fluorine can protect teeth, prevent decayed teeth and promote development and growth of bones, but long-term drinking of water containing high-concentration fluorine can cause diseases such as fluorine plaque teeth, fluorine bone diseases and the like. Fluoride has a certain influence on human health, and about 1-1.5 mg of fluoride is taken by adults every day, and excessive intake can influence the health. The soluble fluoride has high absorption rate, fluorine and calcium have extremely strong affinity, and more than 90% of fluorine in the body is accumulated in calcified tissues such as bones and teeth. The ingestion of large doses of soluble fluoride in a short period of time can cause acute poisoning. Chronic fluorosis is caused by the deposition of fluorine in bone, known as a fluoripathy, manifests as thickened bone, reduced toughness, rough surface, reduced bone cavity, and multiple exogenesis accompanied by osteophytes, which impedes joint movement. In severe cases, the ligament calcifies to deform the limb, which is prone to fracture.
The current common methods for detecting the fluoride ions in water comprise titration methods, fluorescence analysis methods, ion chromatography methods, fluoride ion selective electrode methods and the like, wherein the methods require instruments and equipment, and further require complicated operation and use a large amount of reagents, so that the method is not suitable for on-site rapid detection. Therefore, the method and the product for detecting the fluoride ions, which are suitable for on-site rapid detection, have important application values in the fields of march, camping, industrial and agricultural water supply, daily drinking water and the like. The national standard alizarin zirconium sulfonate visual colorimetry (HJ 487-2009) for detecting the fluoride ions in water uses a colorimetric tube for visual colorimetry, the detection time is long, the operation is troublesome, the linear range is only 0.4-1.5ppm, the sample is often required to be pretreated by distillation and the like due to poor anti-interference capability, and the practical application is difficult. The national standard fluorine reagent spectrophotometry (HJ 488-2009) uses a special color development system, and has wide detection range, higher sensitivity and strong anti-interference capability. However, this method requires a spectrophotometric instrument and is not suitable for rapid detection in situ as is the case with other instrumental analysis methods. As the fluorogenic reagent photometry is a colorimetric method essentially, a plurality of researchers at home and abroad try to transplant the fluorogenic reagent method onto the test paper for more than ten years, so that the on-site rapid detection of the fluorogenic ions in water by the low-cost test paper is realized, but the method is not successful at present, and is turned to the research of developing other color development systems. For example, several documents report methods for detecting fluoride ions by colorimetry and corresponding test paper products [ CN100483113, a visual colorimetric fluoride ion sensing test paper and uses thereof; CN 102942541B-an acceptor compound, its synthesis and its use in colorimetric detection of fluoride ions. Most of these methods utilize interaction of a specific acceptor complex with fluoride ions to change the electron density of the complex to cause a color change for detection. The problem common to these methods is that hydroxide ions in alkaline solutions, like fluoride ions, can cause greater interference with the acceptor complex. These methods are therefore more suitable for the detection of fluoride ions in the organic phase.
The research shows that the difficulty of the national standard fluorine reagent photometry transplanting to the test paper is mainly in the following four aspects. Firstly, on common test paper materials such as filter paper, nitrocellulose and the like, a color reagent system consisting of a fluorine reagent, lanthanum salt and acetone, which is used in a national standard method, is difficult to fix, so that color development is unstable. Secondly, the dispersibility of the components of the color developing agent on the test paper is poor, so that color development is uneven, and the visual colorimetric effect is seriously affected. Thirdly, the color former component is unstable on the test paper and has poor durability. Fourthly, the common calcium and magnesium ions in the water have larger interference, and the photometry can eliminate the interference to a certain extent by subtracting the background and optimizing the detection wavelength, but the test paper cannot be used. These four problems are the main obstacle to the development of the fluorogenic reagent test strip.
Disclosure of Invention
The invention aims to provide a detection method for rapidly detecting fluoride ions in water, a test strip and application thereof, so as to realize rapid and low-cost detection of the fluoride ions in water on site.
The invention aims at realizing the following scheme:
A test paper for detecting the fluoride ion content in water, comprising: the test paper carrying the color reagent is obtained by immersing the test paper into a color reagent solution for a period of time and then drying, wherein the color reagent solution is prepared by mixing 3-methyl amine-alizarin diacetic Acid (ALC) solution, acetic acid-sodium acetate buffer solution, acetylacetone and lanthanum salt solution according to the volume ratio of 3:1:3:3, and polyethylene glycol accounting for 0.5-1 wt% is added into the obtained mixed solution.
Preferably, the concentration of the ALC solution and the lanthanum salt solution is 0.001-0.002mol/L.
Preferably, the pH of the acetic acid-sodium acetate buffer solution is 5.0-5.5.
Preferably, the polyethylene glycol has a molecular weight of 8000.
Preferably, the thickness of the test paper is 0.6-0.9 mm, the test paper is made of super absorbent fiber materials, and the test paper is preferably absorbent paper for chromatography.
Preferably, the test paper carrying the color-developing agent is obtained by immersing the test paper in the color-developing agent solution for 10 minutes and then drying at 45-70 ℃.
A method for preparing test paper for detecting the content of fluoride ions in water, comprising the following steps:
Step 1: cutting the test paper and the rubber plate to a proper size;
step 2: immersing test paper in the color reagent solution for 10 minutes, taking out and draining;
Step 3: and (3) adhering the drained test paper on a rubber plate, and drying in an oven at 45-70 ℃ to obtain the test paper for detecting the fluorine ion content in water.
Compared with the prior art, the invention has the following beneficial effects:
(1) Different from the common buffer solution with the pH of 4.1, the invention adopts a buffer system with the pH of 5.0-5.5, and on the premise of ensuring the stability of a color development system, the invention enhances the action capacities of hydroxyl hydrogen bonds and the like on test paper fibers by reducing the acidity of the system, so that the color development agent is easier to fix on the test paper, and the color development is more stable and sensitive;
(2) The chromatographic absorbent paper adopted by the invention cooperates with the acetylacetone and polyethylene glycol adopted in the color developing agent solution, so that a color developing system and buffer salt can be fully dispersed and fixed in the test paper, thus the test paper has very uniform color development, and is particularly beneficial to the sensitive identification of visual colorimetry; polyethylene glycol adopted in the color developing agent solution is neutral and has certain oxidation resistance, the buffer system is not influenced, the stability of the whole color developing system can be increased, the test paper can be stored for more than 6 months under the condition of normal temperature and light shielding, and if the test paper is stored in a sealed manner, the test paper can be stored for more than 2 years; the acetone solvent selected by the national standard method is a volatile solvent which is not suitable for test paper, and the boiling point of the acetylacetone adopted in the color developing agent solution is up to 180 ℃, so that the color developing agent solution is more suitable for being applied to a test paper system; on one hand, the acetylacetone replaces the common acetone, plays a role in increasing the solubility of the color reagent in the acetic acid-sodium acetate buffer system, and more importantly, the acetylacetone can shield interference by combining a plurality of possibly interfered ions in water, such as metal ions of calcium, magnesium, copper, iron, manganese and the like, so that the anti-interference capability of the method is enhanced. These preferred conditions are combined to enable the more rapid, accurate and sensitive detection of the concentration of fluoride ions in water using fluorogenic reagents, lanthanum salt chromogenic systems.
(3) The allowable fluorine content of drinking water regulated by the world health organization was 1ppm. When the fluorine content in the water to be detected is 0.5ppm, the fluorine ion detection test paper has obvious color change. Therefore, the test paper can be used for conveniently detecting the fluorine ion content of the drinking water.
(4) The fluorine ion test paper prepared by the invention can gradually and uniformly change color within the range of 0.5ppm to 100ppm according to different fluorine contents, and the detection range is far beyond the existing colorimetric method. The standard color card can be manufactured according to different fluorine contents and different color changes of the test paper, and is used for semi-quantitative detection. Meanwhile, the test strip provided by the invention has good stability and can be stored for a long time at normal temperature.
Drawings
FIG. 1 shows the results of detection at a concentration of 0 to 10ppm in an aqueous fluorine ion solution.
FIG. 2 shows the results of detection at a concentration of 20 to 100ppm in an aqueous fluorine ion solution.
Fig. 3 is a standard color chart produced based on the experimental results.
FIG. 4 shows the results of the detection of water samples from different sources in example 2.
FIG. 5 shows the test results of the test strips of example 3.
FIG. 6 shows the results of the test under different color conditions in example 4.
Detailed Description
Example 1
A method for preparing test paper for detecting the content of fluorine ions in water comprises the following steps:
step 1: the chromatographic absorbent paper with the thickness of 0.6 mm is cut to the size of 1 cm long and 5mm wide, and the PVC rubber plate is cut to the width of 5 mm.
Step 2: immersing the water absorbing paper in a developer solution for 10 minutes, taking out, and draining until the water absorbing paper has certain adhesiveness on a rubber plate, wherein the preparation steps of the developer solution are as follows: ALC solution, acetic acid-sodium acetate buffer solution, acetylacetone and lanthanum salt solution are mixed according to the volume ratio of 3:1:3:3, and 0.5wt% of polyethylene glycol with molecular weight of 8000 is added into the obtained mixed solution.
Step 3: and (3) adhering the drained water-absorbing paper on a rubber plate, and drying in an oven at 45 ℃ for 30 minutes to obtain the test paper for detecting the fluorine ion content in water.
And step4, preparing fluoride ion standard solutions with different concentrations to prepare the standard colorimetric card.
Wherein, in the color reagent solution, the preparation process of each solution is as follows:
ALC solution: 0.193g of 3-methylamine-alizarin-diacetic acid (C 14H7O4·CH2N(CH2COOH)2) is weighed, moistened with 5ml of deionized water, dissolved by dropwise addition of 1mol/L sodium hydroxide solution, further added with 0.125g of sodium acetate (CH 3COONa·3H2 O), adjusted to pH 5.0 with 1mol/L hydrochloric acid solution, and diluted to 500ml with deionized water.
Lanthanum salt solution: 0.443g of lanthanum nitrate [ La (NO 3)3·6H2 O ] was weighed, dissolved in a small amount of 1mol/L hydrochloric acid solution, adjusted to pH 5.0 with 1mol/L sodium acetate solution, and diluted to 1000ml with deionized water.
Acetic acid-sodium acetate buffer solution: 35g of anhydrous sodium acetate (CH 3 COONa) were weighed into 800ml of deionized water, 75ml of glacial acetic acid (CH 3 COOH) were added, diluted to 1000ml with deionized water and the pH was adjusted to 5.0 with acetic acid or sodium hydroxide solution on a pH meter.
The preparation process of the fluoride ion standard solution with different concentrations comprises the following steps: weighing 0.2210g of high-grade pure sodium fluoride (NaF) dried at 105 ℃ for 2 hours, dissolving in deionized water, transferring into a 1000ml volumetric flask, diluting to marked lines, uniformly mixing and storing in a polyethylene bottle for later use, wherein each milliliter of the solution contains 100 mug of fluorine. Other concentrations were diluted in proportion respectively.
The standard colorimetric card is prepared as follows: and respectively immersing the test paper into fluorine ion standard solutions with different concentrations, immediately taking out, or respectively dripping 4 drops of fluorine ion standard solutions with different concentrations on the test paper, wherein the fluorine ion standard solutions (NaF) are stable in color development after the concentration of the fluorine ion standard solutions is 0、0.5ppm、1.0ppm、1.5ppm、2.0ppm、2.5ppm、3.0ppm、3.5ppm、4.0ppm、4.5ppm、5.0ppm、5.5ppm、6.0ppm、6.5ppm、7.0ppm、7.5ppm、8.0ppm、8.5ppm、9.0ppm、9.5ppm、10.0ppm、20ppm、30ppm、40ppm、50ppm、60ppm、70ppm、80ppm、90ppm、100ppm,10 minutes in sequence, and observing the color development result. As shown in FIG. 1, the first test piece (No. 1) at the top of FIG. 1 shows the result of ultrapure water, which corresponds to a fluoride ion concentration of 0, and shows a primary color of red, while the second test piece (No. 2) shows the result of a fluoride ion concentration of 0.5ppm, and the test piece color is significantly purple. As the fluoride ion concentration increases stepwise, the purple color on the test paper also deepens stepwise. The color development of the fluorine ion concentration of 20-100ppm is shown in FIG. 2. The color chart is prepared according to the color development result of 10 minutes, and the prepared standard color chart is shown in figure 3, and the test paper of the method has the detection range of 0.5-100ppm, thereby being beneficial to actual detection.
Example 2
The test paper is prepared as in example 1, and is not described in detail herein.
4 Drops of distilled water, city tap water, residential river water sample, lake water sample and industrial river water sample are respectively dripped on the test paper, and the phenomenon is observed after standing for 10 minutes, as shown in fig. 4 (the color development results of distilled water, city tap water, residential river water sample, lake water sample and industrial river water sample are sequentially shown in sequence from top to bottom, with the serial numbers 1-5). The fluorine ion content of the water sample can be obtained by the control color card, and the fluorine ion content is as follows: undetected, 0.5ppm,1ppm,2pppm,3ppm. The results were consistent with spectrophotometric measurements (0.1, 0.5,0.9,2.1,2.9 ppm). From the results, it can be also known that the use of acetylacetone in a color development system does not affect detection due to the high content of calcium and magnesium ions and the like which are common in natural water bodies.
Example 3
Step 1: filter papers with the thickness of 0.6 mm and 0.35 mm respectively and nitrocellulose films with the thickness of 110 micrometers are cut to the sizes of 1 cm long and 5mm wide respectively, and a PVC rubber plate is cut to the width of 5 mm.
Step 2: the three test strips were immersed in the color developer for 10 minutes, respectively. The developer formulation is as described in example 1 and will not be described in detail here.
Step 3: and respectively adhering the soaked and drained test paper on a rubber plate, and drying the test paper in an oven at 45 ℃ for 30 minutes to prepare the test paper for detecting the fluorine ion content in water.
Fourth step: the three test papers were immersed in 2ppm of a standard solution of fluoride ions, and then taken out rapidly, and after 10 minutes, the color development results were observed, as shown in FIG. 5, wherein the number 1 was a filter paper 0.6 mm thick, the number 2 was a filter paper 0.35 mm thick, and the number 3 was a nitrocellulose membrane 110 μm thick. As can be seen from FIG. 5, the reuse of the color development system of example 1 with filter paper and nitrocellulose membrane as test paper does not give a uniform and clear color development on the test paper, which has an adverse effect on visual colorimetry. Wherein the color development effect of the filter paper with the diameter of 0.6 mm, namely the number 1, is slightly better than that of the filter paper with the diameter of 0.35 mm, namely the number 2. Therefore, the invention selects the water absorbing paper with the thickness of about 0.6-0.9 mm as the test paper, and the effect can be optimized. The thickness exceeding 0.9 mm can lead to prolonged drying time, increased dosage of the color reagent and slightly reduced color effect.
Example 4
The test paper preparation steps are shown in example 1 and will not be described in detail herein. However, the components in the color-developing solution used in the step 2 of example 1 were replaced or reduced, and the other processes were unchanged. The result of the detection of the 5ppm fluoride ion solution is shown in FIG. 6. Wherein, the color reagent solution of the test paper (test paper 1) with the serial number of 1 is as follows: mixing an ALC solution, an acetic acid-sodium acetate buffer solution (pH 4.1), acetone and a lanthanum salt solution according to a volume ratio of 3:1:3:3; the developer solution of the test paper (test paper 2) with the serial number of 2 is: mixing an ALC solution, an acetic acid-sodium acetate buffer solution (pH 5.0), acetylacetone and a lanthanum salt solution according to a volume ratio of 3:1:3:3; the developer solution of the test paper (test paper 3) with the serial number 3 is as follows: ALC solution, acetic acid-sodium acetate buffer solution (pH 4.1), acetylacetone and lanthanum salt solution are mixed according to the volume ratio of 3:1:3:3, and 0.5wt% of polyethylene glycol is added into the obtained mixed solution. It should be noted that the concentrations and compositions of the two solutions of the ALC solution and the lanthanum salt solution in the developer solutions of the three test strips were identical to those of example 1.
As can be seen from FIG. 6, the test paper 1 uses the color development system used by the national standard of fluorine reagent, the color development is extremely uneven, and the color development area is obviously deviated, which indicates that the color development agent can not be stably fixed on the test paper, and the color development effect is poor. The test paper 2 is prepared by removing polyethylene glycol from the color development system of the embodiment 1, and the color development uniformity is better than that of the test paper 1, but the color development uniformity does not meet the requirement of visual color comparison, and the test paper without polyethylene glycol can obviously weaken the color development after being stored for more than 30 days at room temperature, thereby indicating the dispersion and protection effects of the polyethylene glycol in the color development system. Meanwhile, experiments also find that when the molecular weight of the polyethylene glycol is less than 8000, the protection effect is poor, and the molecular weight is too large, the solubility in the system is poor. Meanwhile, experiments also find that when the amount of polyethylene glycol added is too small, the dispersing and protecting effects are also deteriorated. When the amount of polyethylene glycol added exceeds 1wt%, the drying time of the test paper is obviously prolonged, and the drying temperature is obviously increased, which is unfavorable for the preparation of the test paper. Test paper 3 is a buffer solution of pH5.0 replaced with a buffer solution of pH4.1 in the color development system of example 1. The result shows that the fixing effect of the color development system on the test paper is poor, so that the color development is uneven and is not obvious. Experiments also find that when the pH value of the buffer solution is between 5.0 and 5.5, the buffer solution can develop color stably and uniformly, but when the pH value exceeds 5.5, the pH value becomes strong, so that the color developing agent becomes turbid, and the detection effect is affected.
Claims (9)
1. A test paper for detecting the fluoride ion content in water, comprising: the test paper carrying the color developing agent is characterized in that the test paper carrying the color developing agent is obtained by immersing the test paper in a color developing agent solution for a period of time and then drying, wherein the color developing agent solution is obtained by mixing 3-methyl amine-alizarin diacetic acid solution, acetic acid-sodium acetate buffer solution, acetylacetone and lanthanum salt solution according to the volume ratio of 3:1:3, and then 0.5 wt-1 wt% of polyethylene glycol is added into the obtained mixed solution.
2. The test paper according to claim 1, wherein the concentration of the ALC solution and the lanthanum salt solution is 0.001-0.002mol/L.
3. The test strip of claim 1, wherein the pH of the acetic acid-sodium acetate buffer solution is 5.0-5.5.
4. The test strip of claim 1, wherein the polyethylene glycol has a molecular weight of 8000.
5. The test strip of claim 1, wherein the test strip has a thickness of 0.6 to 0.9 mm, and is a paper made of a super absorbent fibrous material, preferably a chromatographic absorbent paper.
6. The test paper according to claim 1, wherein the test paper carrying the color-developing agent is obtained by immersing the test paper in the color-developing agent solution for 10 minutes and then drying at 45 to 70 ℃.
7. The test strip of claim 1, further comprising a glue plate to which the test strip is secured.
8. A method for rapidly detecting fluoride ions in water, which is characterized in that the test paper according to any one of claims 1-7 is adopted to rapidly detect fluoride ions in water.
9. The method of claim 8, wherein standard colorimetric cards are prepared by dripping or immersing the standard solutions of fluoride ions with different concentrations into the test paper of any one of claims 1-7, then the test paper of any one of claims 1-7 is adopted to detect the liquid to be detected, and the fluoride ion content of the liquid to be detected is obtained by contrasting the standard colorimetric cards.
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| CN202410049265.4A CN118311024A (en) | 2024-01-12 | 2024-01-12 | Method and test paper for rapidly detecting fluoride ions in water |
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| CN202410049265.4A CN118311024A (en) | 2024-01-12 | 2024-01-12 | Method and test paper for rapidly detecting fluoride ions in water |
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