Use method of rapid screening kit for rapidly detecting formaldehyde

Abstract

The invention relates to the technical field of rapid screening kits, in particular to a use method of a rapid screening kit for rapidly detecting formaldehyde, which comprises the following steps: dissolving 0.5% AHMT in a 0.1 M hydrochloric acid solution, mixing with NaOH solid powder to prepare a color developing agent, treating a sample, taking the treated sample as a sample to-be-detected solution, diluting the sample to-be-detected solution with the dilution ratio of 10, taking out a detection hole strip, and detecting the formaldehyde in the sample to-be-detected solution. Adding one drop of a color developing agent and two drops of a 3% hydrogen peroxide solution into the detection hole, adding three drops of a sample to-be-detected solution by using a suction tube, mixing and standing for 7 minutes, and finally interpreting a result through a colorimetric card and multiplying the result by a dilution multiple to obtain the content of formaldehyde. According to the method, an optimized AHMT color development system is adopted, the AHMT color development system is specifically combined with formaldehyde under the alkaline condition and oxidized to generate a stable purplish red complex, the detection sensitivity is remarkably improved, and meanwhile, the color development reaction has excellent anti-interference capacity by strictly controlling the solution proportion and reaction conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of rapid screening kits, and in particular to a method for using the rapid screening kit for rapidly detecting formaldehyde. Background Art

[0002] Formaldehyde, a carcinogen, is often illegally added to food for preservation, bleaching and improving appearance, especially in water-soaked products (such as beef tripe and jellyfish), dried aquatic products (such as scallops and dried shrimp) and soy products. my country's GB2760 "National Food Safety Standard" explicitly prohibits the use of formaldehyde as a food additive.

[0003] Traditional formaldehyde detection methods include high-performance liquid chromatography, acetylacetone method and fuchsin sulfite method, but they have problems such as strong equipment dependence, cumbersome operation steps, low sensitivity, poor reagent stability, and poor anti-interference ability. They are difficult to meet the needs of convenience and efficiency in rapid detection. Although existing rapid test kits are constantly developing, it is still difficult to distinguish formaldehyde from other aldehydes. At the same time, extraction and color development are more difficult when facing high-water samples or fibrous samples.

[0004] Therefore, in order to solve the above problems, the present invention proposes a method for using a rapid screening kit for rapid detection of formaldehyde. Summary of the Invention

[0005] In order to overcome the problems of low sensitivity and poor anti-interference ability of existing rapid detection kits, the present invention provides a method for using a rapid screening kit for rapid detection of formaldehyde.

[0006] The technical solution of the present invention is: a method for using a rapid screening kit for rapid detection of formaldehyde, comprising the following steps:

[0007] S1, add all the liquid of 0.5% AHMT dissolved in 0.1M hydrochloric acid solution into the bottle of NaOH solid powder and shake well to prepare the color developer;

[0008] S2, process the sample, and after the processing, use it as the sample solution to be tested, with a dilution factor of 10;

[0009] S3, take out the test strip, add 1 drop of color developer and 2 drops of 3% hydrogen peroxide solution to the test well, add 3 drops of the sample solution with a pipette, and pipette up and down to mix the solution. Let it stand and observe the color change of the liquid in the test strip;

[0010] S4, compare the color change of the liquid in the detection hole with the color scale card to preliminarily obtain the concentration value, and then multiply it by the dilution factor to obtain the formaldehyde content in the sample to be tested.

[0011] Preferably, the sample processing step comprises:

[0012] For liquid samples, draw 100 μL of soaking solution, add 900 μL of purified water, mix well and use as the sample solution, with a dilution factor of 10;

[0013] For dry samples, accurately weigh 1 g of chopped sample, add 10 mL of purified water, vortex extract for 1 minute, let it stand for 5 minutes, and take the supernatant as the sample solution, with a dilution factor of 10.

[0014] Preferably, the 0.5% AHMT dissolved in 0.1 M hydrochloric acid solution tends to clump when stored at low temperatures and needs to be dissolved in a 37° C. water bath before use.

[0015] Preferably, in the sample processing step, if the sulfur dioxide content in the sample is low, the sampling amount can be increased; if the sulfur dioxide content is high, the sampling amount can be reduced and the sulfur dioxide content can be converted proportionally.

[0016] Preferably, in the result interpretation step, if the color of the liquid remains unchanged or is lighter than the color of 0.5 level on the color scale card, it means that the sample does not contain formaldehyde; if the color of the liquid turns purple-red or darker than the color of 0.5 level, it means that the sample contains formaldehyde.

[0017] Preferably, the kit includes 1 bottle of 0.5% AHMT dissolved in 0.1M hydrochloric acid solution, 1 bottle of NaOH solid powder, 1 bottle of 3% hydrogen peroxide solution, 1 pack of sample cups, 1 color scale card, 1 pack of 0.2mL pipettes, and 1 pack of detection well strips. Each kit contains a total of 100 copies of the above materials.

[0018] Preferably, the detection limit of the kit is: 0.5 mg / Kg for standard solution and 5 mg / Kg for sample.

[0019] Preferably, in the sample processing step, the dry sample is shredded to such an extent that the sample can fully come into contact with pure water.

[0020] Preferably, in the sample detection step, the standing time is 7 minutes.

[0021] Preferably, the color scale card is used for semi-quantitative detection, and the formaldehyde content is preliminarily determined by color comparison.

[0022] Beneficial effects of the present invention:

[0023] 1. The formaldehyde rapid screening kit of the present invention adopts an optimized AHMT color development system, which specifically binds to formaldehyde under alkaline conditions and oxidizes it to form a stable purple-red complex, significantly improving the sensitivity of detection. It can effectively identify trace amounts of formaldehyde residues in food and meet the strict requirements of food safety supervision.

[0024] 2. By strictly controlling the ratio and reaction conditions of 0.5% AHMT dissolved in 0.1M hydrochloric acid solution, NaOH solid powder, and 3% hydrogen peroxide solution, the present invention enables the color development reaction to have excellent anti-interference ability, can effectively distinguish formaldehyde from other aldehydes, and avoid false positive or false negative results. It is particularly suitable for the detection of samples with complex ingredients such as water-soaked products, dried aquatic products, and soy products.

[0025] 3. The operating method of the present invention has been highly simplified and standardized. Only three steps of "sample addition - mixing - colorimetry" are required to complete the detection. The color development time is shortened to 7 minutes. Without the need for complex instruments and professional operating skills, ordinary users can easily complete it, greatly improving detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 What is shown is a schematic diagram of the workflow of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0028] See also Figure 1 The present invention provides an embodiment: a method for using a rapid screening kit for rapid detection of formaldehyde, comprising the following steps:

[0029] S1, add all the liquid of 0.5% AHMT dissolved in 0.1M hydrochloric acid solution into the bottle of NaOH solid powder and shake well to prepare the color developer;

[0030] S2, process the sample, and after the processing, use it as the sample solution to be tested, with a dilution factor of 10;

[0031] S3, take out the test strip, add 1 drop of color developer and 2 drops of 3% hydrogen peroxide solution to the test well, add 3 drops of the sample solution with a pipette, and pipette up and down to mix the solution. Let it stand and observe the color change of the liquid in the test strip;

[0032] S4, compare the color change of the liquid in the detection hole with the color scale card to preliminarily obtain the concentration value, and then multiply it by the dilution factor to obtain the formaldehyde content in the sample to be tested.

[0033] The sample processing steps include:

[0034] For liquid samples, draw 100 μL of soaking solution, add 900 μL of purified water, mix well and use as the sample solution, with a dilution factor of 10;

[0035] For dry samples, accurately weigh 1 g of chopped sample, add 10 mL of purified water, vortex extract for 1 minute, let it stand for 5 minutes, and take the supernatant as the sample solution, with a dilution factor of 10.

[0036] The 0.5% AHMT dissolved in 0.1 M hydrochloric acid solution tends to clump when stored at low temperatures and needs to be dissolved in a 37° C. water bath before use.

[0037] In the sample processing step, if the sulfur dioxide content in the sample is low, the sampling amount can be increased; if the sulfur dioxide content is high, the sampling amount can be reduced and the sulfur dioxide content can be converted proportionally.

[0038] In the result interpretation step, if the color of the liquid remains unchanged or is lighter than the color of the 0.5 level on the color scale card, it means that the sample does not contain formaldehyde; if the color of the liquid turns purple-red or darker than the color of the 0.5 level, it means that the sample contains formaldehyde.

[0039] The kit includes 1 bottle of 0.5% AHMT dissolved in 0.1M hydrochloric acid solution, 1 bottle of NaOH solid powder, 1 bottle of 3% hydrogen peroxide solution, 1 package of sample cups, 1 color scale card, 1 package of 0.2mL pipettes, and 1 package of detection well strips. Each kit contains a total of 100 copies of the above materials.

[0040] The detection limits of the kit are: 0.5 mg / Kg for standard solution and 5 mg / Kg for sample.

[0041] In the sample processing step, the dry sample must be chopped to a degree that ensures that the sample can fully come into contact with pure water.

[0042] In the sample detection step, the standing time is 7 minutes.

[0043] The color scale card is used for semi-quantitative detection, and the formaldehyde content is preliminarily determined by color comparison.

[0044] Furthermore, the present invention provides an embodiment for detecting formaldehyde in water-soaked buffalo tripe:

[0045] Take 1g of commercially available water-soaked beef tripe sample, cut it into pieces, add 10mL of pure water, vortex and extract for 1 minute, let it stand for 5 minutes, take the supernatant as the test liquid, take the detection well strip, add 1 drop of pre-prepared color developer, 2 drops of 3% hydrogen peroxide solution and 3 drops of test liquid in turn, mix with a pipette and let it stand for 7 minutes. It was observed that the solution was obviously purple-red. Compared with the color scale card, the reading corresponded to 0.8mg / L. After multiplying by the dilution factor 10, the formaldehyde content in the sample was 8mg / kg, which exceeded the national limit standard, proving that the beef tripe had the problem of illegal addition of formaldehyde.

[0046] Furthermore, the present invention provides an embodiment for detecting formaldehyde in dried sea cucumbers:

[0047] Weigh 1 g of dried sea cucumber sample, grind it, add 10 mL of pure water, vortex extract for 1 minute, let it stand for 5 minutes, and take the supernatant. After adding the color developer and oxidant according to standard operation, the reaction liquid turned light pink. The concentration was determined to be 0.3 mg / L by colorimetry, and the actual content of the sample was 3 mg / kg, which was lower than the detection limit of 5 mg / kg and was judged to be negative. To verify the reliability of the test, the same sample was added with 0.5 mg / kg formaldehyde standard and tested. The results showed that the concentration was significantly increased, confirming that this method can effectively identify trace formaldehyde residues in dried sea cucumbers.

[0048] Furthermore, the present invention provides an embodiment for detecting formaldehyde in bean products (bean curd sticks):

[0049] One gram of the suspected bean curd stick sample was cut into pieces and tested according to the standard method. It was found that the color reaction was abnormally rapid and the color was dark purple, far exceeding the highest scale of the color scale card (5 mg / L). The sample was then diluted 100 times and retested, and the reading was 2.5 mg / L. The formaldehyde content of the original sample was calculated to be as high as 250 mg / kg, which was seriously exceeded. The result was consistent with the subsequent laboratory high-performance liquid chromatography determination result (238 mg / kg) by 95%, confirming that this kit has reliable detection capabilities for high-concentration formaldehyde samples and that the detection range can be expanded by adjusting the dilution factor.

[0050] Furthermore, the present invention provides an embodiment for direct detection of aquatic product soaking liquid:

[0051] For on-site spot checks by market supervision, 100 μL of the soaking liquid of the suspected illegal soaking water product was directly taken, diluted with 900 μL of pure water and tested. The color development result showed 1.2 mg / L after 7 minutes, which was converted to a stock solution concentration of 12 mg / L, consistent with the result of the acetylacetone method control experiment (11.8 mg / L) conducted at the same time. This proves that this method can obtain accurate results for liquid samples without complex pretreatment, and is particularly suitable for rapid market screening. The entire detection process can be completed within 10 minutes.

[0052] Furthermore, the present invention provides an embodiment for detecting and verifying in a low temperature environment:

[0053] At a low temperature of 10°C, the condensed 0.5% AHMT was dissolved in 0.1M hydrochloric acid solution and placed in a 37°C water bath to dissolve as required by the instructions. A standard formaldehyde solution (1 mg / L) of known concentration was then tested. The results showed that the deviation from the test results at room temperature (25°C) was less than 5%, and the color development time remained within 7 minutes. This demonstrates that the low-temperature treatment scheme designed for this kit effectively ensures detection stability at different ambient temperatures, resolving the industry problem of poor performance of traditional reagents in winter.

[0054] Through the above steps, by adopting an optimized AHMT color development system, it specifically binds to formaldehyde under alkaline conditions and oxidizes it to form a stable purple-red complex, thereby significantly improving the sensitivity of detection and being able to effectively identify trace amounts of formaldehyde residues in food. At the same time, by strictly controlling the ratio and reaction conditions of 0.5% AHMT dissolved in 0.1M hydrochloric acid solution, NaOH solid powder and 3% hydrogen peroxide solution, the color development reaction has excellent anti-interference ability, thereby solving the problems of low sensitivity and poor anti-interference ability of existing rapid test kits.

Claims

1. A method for using a rapid screening kit for rapid detection of formaldehyde, characterized in that: The following steps are included: S1, add all the liquid of 0.5% AHMT dissolved in 0.1M hydrochloric acid solution into the bottle of NaOH solid powder and shake well to prepare the color developer; S2, process the sample, and after the processing, use it as the sample solution to be tested, with a dilution factor of 10; S3, perform sample testing, take out the test strip, add 1 drop of color developer and 2 drops of 3% hydrogen peroxide solution to the test well, add 3 drops of sample solution with a pipette, and pipette up and down to mix the solution, let it stand, and observe the color change of the liquid in the test strip; S4, compare the color change of the liquid in the detection hole with the color scale card to preliminarily obtain the concentration value, and then multiply it by the dilution factor to obtain the formaldehyde content in the sample to be tested.

2. The method for using the rapid screening kit for rapid detection of formaldehyde according to claim 1, characterized in that: The sample processing steps include: For liquid samples, draw 100 μL of soaking solution, add 900 μL of purified water, mix well and use as the sample solution, with a dilution factor of 10; For dry samples, accurately weigh 1 g of chopped sample, add 10 mL of purified water, vortex extract for 1 minute, let it stand for 5 minutes, and take the supernatant as the sample solution, with a dilution factor of 10.

3. The method for using the rapid screening kit for rapid formaldehyde detection according to claim 1, wherein: The 0.5% AHMT dissolved in 0.1 M hydrochloric acid solution tends to clump when stored at low temperatures and needs to be dissolved in a 37° C. water bath before use.

4. The method for using the rapid screening kit for rapid detection of formaldehyde according to claim 2, characterized in that: In the sample processing step, if the sulfur dioxide content in the sample is low, the sampling amount can be increased; if the sulfur dioxide content is high, the sampling amount can be reduced and the sulfur dioxide content can be converted proportionally.

5. The method for using the rapid screening kit for rapid detection of formaldehyde according to claim 1, characterized in that: In the result interpretation step, if the color of the liquid remains unchanged or is lighter than the color of the 0.5 level on the color scale card, it means that the sample does not contain formaldehyde; if the color of the liquid turns purple-red or darker than the color of the 0.5 level, it means that the sample contains formaldehyde.

6. The method for using the rapid screening kit for rapid formaldehyde detection according to claim 1, characterized in that: The kit includes 1 bottle of 0.5% AHMT dissolved in 0.1M hydrochloric acid solution, 1 bottle of NaOH solid powder, 1 bottle of 3% hydrogen peroxide solution, 1 package of sample cups, 1 color scale card, 1 package of 0.2mL pipettes, and 1 package of detection well strips. Each kit contains a total of 100 copies of the above materials.

7. The method for using the rapid screening kit for rapid detection of formaldehyde according to claim 1, characterized in that: The detection limits of the kit are: 0.5 mg / Kg for standard solution and 5 mg / Kg for sample.

8. The method for using the rapid screening kit for rapid detection of formaldehyde according to claim 1, characterized in that: In the sample processing step, the dry sample must be chopped to ensure that the sample can fully contact with pure water.

9. The method for using the rapid screening kit for rapid detection of formaldehyde according to claim 1, characterized in that: In the sample detection step, the standing time is 7 minutes.

10. The method for using the rapid screening kit for rapid formaldehyde detection according to claim 1, characterized in that: The color scale card is used for semi-quantitative detection, and the formaldehyde content is preliminarily determined by color comparison.

Images