CN103969258B - A kind of bore hole fast detecting Cd2+Test paper and method - Google Patents

Abstract

The invention provides a test paper and method for rapid detection of Cd ²⁺ with the naked eye. It uses the principle that quantum dots generate photoelectrons under the irradiation of visible light to change the color of the dye to invent a new detection test paper and method. The cost of the prepared test paper is extremely low , which can qualitatively or semi-quantitatively detect cadmium in food or water, with fast determination speed and high sensitivity. The detection method is simple and has low technical requirements for operators, which is very suitable for on-site detection.

Description

A test paper and method for rapid detection of Cd2+ with naked eyes

1. Technical field

The invention relates to a test paper and a method for detecting heavy metal ions, in particular to a test paper and a method for rapidly detecting Cd2 ⁺ with naked eyes.

2. Background technology

Cadmium is a heavy metal pollutant under key control in my country and belongs to the first category of pollutants. In addition to causing acute and chronic poisoning, it also has certain teratogenic, carcinogenic and mutagenic effects. The main hazard is chronic poisoning caused by accumulation in the body. The most important way for the body to absorb cadmium is food, and cadmium in food mainly comes from environmental pollution. Therefore, monitoring the content of cadmium in the environment is an important measure to control the intake of cadmium in the human body, prevent and reduce the harm of cadmium to the human body.

There are many detection methods for cadmium, such as: spectrophotometry, atomic absorption method, polarographic catalytic wave method, single-scan polarographic method, stripping voltammetry, potential stripping method, inductively coupled plasma emission spectrometry, neutron activation analysis method , mass spectrometry, chromatography, electrochemical biosensor method, and the combination of various methods, etc., most of them require expensive instruments, and the operation is complicated, requiring specialized technicians to complete.

3. Contents of the invention

The purpose of the present invention is to provide a test paper and method for rapid detection of Cd ²⁺ with naked eyes. This test paper and method should be able to qualitatively or semi-quantitatively detect cadmium in food or water, which can not only save a lot of manpower, material and financial resources, but also can be carried by the test paper. Convenient, simple method, very suitable for on-site detection.

A kind of naked-eye rapid detection Cd ²⁺ test paper provided by the invention is made by the following method:

(1) Synthesize ZnS quantum dot aqueous solution with 0.1M Na ₂ S ethanol aqueous solution and 0.1M Zn(Ac) ₂ ethanol aqueous solution at a volume ratio of 1:1, and the volume ratio of ethanol to water is 1:3; configuration Concentration is the nitro blue tetrazolium blue (NBT) aqueous solution of 1mg/mL;

(2) ZnS quantum dot aqueous solution is coated on glass fiber paper, and NBT aqueous solution is scratched on strip nitrocellulose membrane, puts to dry;

(3) Paste the scratched nitrocellulose membrane and the glass fiber paper coated with ZnS quantum dots on the hard kraft cardboard successively, and stick the polyester fiber under the glass fiber paper, that is, the end of the cardboard as a sample pad, and then place the The pasted cardboard is cut into strips of test paper along the longitudinal direction perpendicular to the NBT scratch line, and the location of the NBT scratch is the indicator area.

Described glass fiber also can be polyester fiber, acetate fiber, nitrocellulose.

A kind of naked-eye rapid detection method for ^Cd provided by the invention, the steps include:

(1) Insert the test strip made above into the liquid to be tested, siphon it for 30 seconds to 10 minutes, and read the color of the indicator area under sunlight or other visible light;

(2) Judging the content of cadmium ions in the sample to be tested according to the color of the indicator area: if the color of the indicator area is dark blue, it indicates that the solution to be tested does not contain cadmium ions or the content is very small; if the color of the indicator area is light blue, it indicates that cadmium ions The content is between 1×10 ^-6 M～1×10 ^-4 M; if the color is yellow or colorless, it indicates that the content of cadmium ion is between 1×10 ^-4 M and 1×10 ^-2 M.

The invention utilizes that cadmium ions have a specific destruction effect on quantum dots so as to inhibit the photoelectric color change process for measurement. The prepared test paper has extremely low cost, high determination speed and high sensitivity. At the same time, the operation is very simple and has low technical requirements for operators. It is suitable for the detection of cadmium ions in environmental monitoring, on-site determination and other occasions.

4. Description of drawings

Fig. 1 is a kind of naked-eye rapid detection Cd ²⁺ test paper structure schematic diagram of the present invention

5. Specific implementation

Example 1.

(1) ZnS quantum dots were synthesized using Na ₂ S as sulfur source. The specific operation method is to prepare 50 mL each of 0.1M Zn(Ac) ₂ and 0.1M Na ₂ S ethanol aqueous solution (the volume ratio of water and ethanol is 3:1), and adjust Zn(Ac) ₂ with HAc. The pH=5 of the ethanol solution. Add the Zn(Ac) ₂ water and ethanol solution dropwise to the Na ₂ S water and alcohol solution under stirring at room temperature (control the dropping speed at 2 mL-3 mL per minute), and continue to stir for 30 minutes after the dropping. After centrifugation, the precipitate was washed three times with water and absolute ethanol, and vacuum-dried at 40°C for 2 hours to obtain ZnS quantum dots, which could be stored at 4°C for 3 months.

(2) Make NBT powder into 1 mg/mL aqueous solution.

(3) The ZnS quantum dot aqueous solution is coated on the glass fiber mat, the NBT aqueous solution is scratched on the nitrocellulose membrane, and dried;

(4) Paste the scored nitrocellulose membrane and the glass fiber paper coated with ZnS quantum dots on the hard kraft cardboard in sequence, and stick polyester fiber under the glass fiber paper, that is, the end of the cardboard, as a sample pad. Afterwards, the pasted cardboard was cut into strips of test paper along the longitudinal direction perpendicular to the NBT scratch line. The position where the NBT scratches are located is the indicator area (that is, the indicator line in Figure 1).

The sample pad area of the prepared test paper was immersed in a cadmium acetate solution with a concentration of 1×10 ^-4 M, siphoned for 3 minutes, and then placed under sunlight. The color of the indicator area under light is colorless, and it is judged that the concentration of cadmium ions is between 1×10 ^-4 M and 1×10 ^-2 M.

Example 2. Prepare test paper according to Example 1, insert the sample area of the test paper into the prepared cadmium ion solution with a concentration of 1×10 ⁻⁵ M, and siphon for 3 minutes. When illuminated by light, the indicator line turns light blue, and it is judged that the content of cadmium ions is between 1×10 ^-6 M and 1×10 ^-4 M.

Example 3

(1) Prepare a solution containing Zn ²⁺ , Mg ²⁺ , Ca ²⁺ , Al ³⁺ , SO ₄ ^2- , NO ₃ ^- , and PO ₄ ^3- ions at a concentration of 0.01M each (without cadmium ions). .

(2) Prepare a test paper according to Example 1, insert the sample area of the test paper into the prepared solution, and siphon for 3 minutes. When illuminated by light, the indicator line turns dark blue, indicating that the solution does not contain cadmium ions.

Embodiment 4. make test paper according to embodiment 1, insert the test paper sample area in the tap water sample, siphon 3 minutes. When exposed to sunlight, the indicator line turns dark blue, indicating that the tap water sample does not contain cadmium ions.

Embodiment 5. Take a river water sample near a certain factory, and preliminarily judge that the river water has been polluted by cadmium discharged. Test paper was made according to steps 1-4 in Example 1, and the sample area of the test paper was inserted into the river water sample polluted by cadmium, and siphoned for 3 minutes. When illuminated by sunlight, the indicator area turns light blue. It is judged that the cadmium ion content in the river water sample is between 1×10 ^-6 M and 1×10 ^-4 M, which means it has been polluted.

Embodiment 6. make test paper by embodiment 1, the test paper sample area is inserted in the river water sample that does not know whether to be polluted, siphon 5 minutes. When exposed to sunlight, the indicator line turns dark blue, indicating that the river water sample does not contain cadmium ions and is not polluted.

Experiments have proved that the cadmium ion detection test paper and the method of the present invention have fast determination speed, strong selectivity, sensitivity and reliability. Compared with the traditional method, the detection cost is reduced, the detection efficiency is improved, and it is very suitable for the rapid determination of actual samples.

Claims (3)

1. a kind of naked-eye rapid detection Cd ²⁺ test paper, it is characterized in that, make by the method for following steps: (1) Synthesize ZnS quantum dot solution with 0.1M Na ₂ S ethanol aqueous solution and 0.1M Zn(Ac) ₂ ethanol aqueous solution at a volume ratio of 1:1, and the volume ratio of ethanol and water is 1:3; configuration NBT aqueous solution with a concentration of 1 mg/mL; (2) the ZnS quantum dot solution is coated on the glass fiber paper, the NBT aqueous solution is scratched on the strip nitrocellulose membrane, and dried; (3) Paste the scratched nitrocellulose membrane and the glass fiber paper coated with ZnS quantum dots on the hard kraft cardboard successively, and stick the polyester fiber under the glass fiber paper, that is, the end of the cardboard as a sample pad, and then place the The pasted cardboard is cut into strips of test paper along the longitudinal direction perpendicular to the NBT scratch line, and the position of the NBT scratch is the indicator line. 2. the test paper of a kind of naked eye rapid detection Cd ²⁺ as claimed in claim 1, is characterized in that, described glass fiber is replaced with polyester fiber, acetate fiber or nitrocellulose. 3. A method for naked-eye rapid detection of Cd ²⁺ , characterized in that the steps comprise: (1) Insert the test strip described in claim 1 or 2 into the liquid to be tested, siphon it for 30 seconds to 10 minutes, and read the color of the indicator area under sunlight or other visible light irradiation; (2) Judging the content of cadmium ions in the sample to be tested according to the color of the indicator area: if the color of the indicator area is dark blue, it indicates that the solution to be tested does not contain cadmium ions or the content is very small; if the color of the indicator area is light blue, it indicates that cadmium ions The content is between 1×10 ^-6 M～1×10 ^-4 M; if the color is yellow or colorless, it indicates that the content of cadmium ion is between 1×10 ^-4 M and 1×10 ^-2 M.