Bleaching method for specimen with hydroxyheme deposition caused by formaldehyde oxidation

Abstract

The invention provides a bleaching method for a specimen with hydroxyheme deposition caused by formaldehyde oxidation, and belongs to the technical field of biological plasticization. The bleaching method for the specimen with hydroxyheme deposition caused by formaldehyde oxidation comprises the following steps: sequentially immersing the specimen into a ferrous sulfate solution, a hydrogen peroxide solution and an oxalic acid solution for reaction, the specimen is a specimen of hydroxyheme deposition caused by formaldehyde oxidation. According to the method, ferrous ions in ferrous sulfate and heme pigment ions form a stable complex, so that the chemical property of the pigment is fundamentally changed, the pigment is more easily decomposed and removed by subsequent hydrogen peroxide, and finally, the color of a specimen is closer to ideal milk white.

Description

Technical Field

[0001] This invention relates to the field of bioplasticization technology, and more particularly to a bleaching method for specimens containing hydroxyheme deposited due to formaldehyde oxidation. Background Technology

[0002] In the fields of plastination, anatomy teaching, and specimen preservation, formalin (formaldehyde solution) is a commonly used reagent for the long-term fixation and preservation of biological tissue specimens. However, with prolonged preservation, the formaldehyde in the specimen oxidizes, causing heme in the blood to be converted into hydroxyheme and deposited in the tissue, giving the specimen an unsightly dark red or dark brown color. This color change not only affects the visual appearance of the specimen but also obscures its original anatomical details, hindering teaching observation, scientific exhibitions, and subsequent plastination processes.

[0003] To address these issues, the conventional technique involves bleaching specimens with hydrogen peroxide. However, for stubborn pigment deposits like hydroxyheme caused by formaldehyde oxidation, the strong oxidizing effect of hydrogen peroxide alone is minimal. If the treatment time is prolonged or the hydrogen peroxide concentration is increased to improve bleaching efficiency, its intense oxidizing properties can damage the specimen's microscopic and macroscopic structures, leading to loose muscle tissue, brittle and even fragmented cancellous and compact bone, ultimately causing permanent damage or even rendering the specimen unusable. Therefore, the conventional hydrogen peroxide bleaching method presents an irreconcilable contradiction between effective decolorization and preserving the specimen's integrity.

[0004] To improve bleaching results, several improvements have been developed in existing technologies. For example, Chinese invention patent CN119908353A discloses a bleaching method using potassium permanganate, oxalic acid, and hydrogen peroxide in sequence. This method first utilizes the strong oxidizing properties of potassium permanganate to initially oxidize the deposited pigments, then uses oxalic acid to reduce and remove the residual color from the potassium permanganate, and finally performs final bleaching with hydrogen peroxide. Compared to single hydrogen peroxide treatment, this existing technology improves the removal capacity for stubborn pigments to some extent. However, this existing technology still has certain limitations: First, the first step uses the strong oxidant potassium permanganate, which still poses a certain risk of oxidative stress to the specimen tissue itself, especially when processing delicate or aged specimens; second, the core idea of ​​this method is still based on multi-stage strong oxidation-reduction chemical attack, and the gentleness and controllability of the process need to be improved, requiring high operational precision; finally, for some specimens with abnormally severe pigment deposition or special structures, there is still room for further improvement in the final bleaching effect (color approaching white) and the degree of structural protection.

[0005] Therefore, it is of great significance to provide a bleaching method that has a more significant bleaching effect, is gentler on the specimen tissue, and can better balance decolorization and structural integrity. Summary of the Invention

[0006] The purpose of this invention is to provide a bleaching method for specimens containing hydroxyheme deposited due to formaldehyde oxidation, which solves the technical problem in the prior art that it is difficult to achieve both bleaching effect and specimen protection.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a bleaching method for specimens containing hydroxyheme deposited due to formaldehyde oxidation, comprising the following steps: The specimen is then sequentially immersed in ferrous sulfate solution, hydrogen peroxide solution, and oxalic acid solution to carry out the reaction. The specimen was a sample of hydroxyheme deposition caused by formaldehyde oxidation.

[0008] Furthermore, the concentration of the ferrous sulfate solution is 10~15 g / L.

[0009] Furthermore, the pH of the ferrous sulfate solution is 5-6, and citric acid is used to adjust the pH.

[0010] Furthermore, the reaction time in the ferrous sulfate solution is 6-8 hours.

[0011] Furthermore, the mass concentration of the hydrogen peroxide aqueous solution is 6-8%; The pH of the hydrogen peroxide solution is 7-8, and the reagent used to adjust the pH is anhydrous sodium carbonate.

[0012] Furthermore, the hydrogen peroxide solution also contains sodium silicate at a mass concentration of 0.5-1%; After adding sodium silicate, the pH of the hydrogen peroxide solution is 10-11.

[0013] Furthermore, the reaction time in the hydrogen peroxide solution is 8-12 hours.

[0014] Furthermore, the oxalic acid solution has a mass concentration of 1-2%.

[0015] Furthermore, the reaction time in oxalic acid solution is 12-36 hours.

[0016] The beneficial effects of this invention are: 1) This invention fundamentally changes the chemical properties of the pigment by forming a stable complex between the ferrous ions in ferrous sulfate and the heme pigment ions, making it easier for the pigment to be decomposed and removed by hydrogen peroxide, and ultimately making the sample color significantly lighter and tending to be milky white. 2) This invention adjusts the pH value by adding citric acid, inhibiting the hydrolysis and precipitation of ferrous sulfate and avoiding potential physical damage to the microstructure of the specimen caused by the deposition of ineffective components; at the same time, by using anhydrous sodium carbonate and sodium silicate to precisely control the pH and stability of the reaction environment, it effectively inhibits the indiscriminate attack of strong oxidizing substances produced by excessive decomposition of hydrogen peroxide on muscle fibers and bone tissue, thereby significantly reducing the phenomenon of loose muscle structure and fragmentation of cancellous or compact bone in the specimen. 3) By introducing pH adjusters (citric acid, sodium carbonate) and stabilizers (sodium silicate), this invention allows the entire chemical treatment process to be under milder and more controllable reaction conditions, reducing specimen damage caused by small fluctuations in reagent concentration or reaction time. It changes the traditional bleaching method for gross specimens, solves the problem of specimens that cannot be treated by conventional bleaching methods such as hydrogen peroxide, and ensures the integrity of the specimens. 4) This invention employs a combination of complexation pretreatment and stabilization bleaching technology, which significantly improves the bleaching effect on stubborn pigment deposition caused by formaldehyde oxidation. This not only allows visitors to more clearly identify the original structure of the specimen, but also fully protects the structural integrity of the specimen, ensuring that the structure is more distinct. While improving the identifiability of the specimen, it also helps in the preparation and exhibition of the specimen. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the original color of the specimen before processing in Example 1; Figure 2 This is a schematic diagram showing the color of the specimen treated with ferrous sulfate solution in Example 1; Figure 3 This is a schematic diagram showing the color of the specimen treated with hydrogen peroxide solution in Example 1; Figure 4 This is a schematic diagram showing the color of the specimen treated with oxalic acid solution in Example 1; Figure 5 This is a schematic diagram showing the color of the specimen after all processing in Example 1. Detailed Implementation

[0018] This invention provides a bleaching method for specimens containing hydroxyheme deposited due to formaldehyde oxidation, comprising the following steps: The specimen is then sequentially immersed in ferrous sulfate solution, hydrogen peroxide solution, and oxalic acid solution to carry out the reaction. The specimen was a sample of hydroxyheme deposition caused by formaldehyde oxidation.

[0019] In this invention, the concentration of the ferrous sulfate solution is 10-15 g / L, preferably 11-14 g / L, and more preferably 12-13 g / L.

[0020] In this invention, the pH of the ferrous sulfate solution is 5-6, preferably 5.2-5.8, and more preferably 5.4-5.6; the reagent used to adjust the pH is preferably citric acid.

[0021] In this invention, the purpose of adding citric acid to adjust the pH is to inhibit the hydrolysis of ferrous sulfate.

[0022] In this invention, the reaction time in the ferrous sulfate solution is 6-8 hours, preferably 6.5-7.5 hours, and more preferably 7 hours.

[0023] In this invention, the mass concentration of the hydrogen peroxide aqueous solution is 6-8%, preferably 6.5-7.5%, and more preferably 7%. The pH of the hydrogen peroxide solution is 7-8, preferably 7.2-7.8, and more preferably 7.4-7.6; the reagent used to adjust the pH is preferably anhydrous sodium carbonate.

[0024] In this invention, the purpose of adding anhydrous sodium carbonate is to reduce specimen damage.

[0025] In this invention, the hydrogen peroxide aqueous solution further contains sodium silicate at a mass concentration of 0.5-1%, preferably 0.6-0.9%, and more preferably 0.7-0.8%. After adding sodium silicate, the pH of the hydrogen peroxide solution is 10-11, preferably 10.2-10.8, and more preferably 10.4-10.6.

[0026] In this invention, sodium silicate is used as a stabilizer. The purpose of adding sodium silicate is to prevent metal ions from damaging the fur.

[0027] In this invention, the reaction time in the hydrogen peroxide aqueous solution is 8~12h, preferably 8.5~11.5h, and more preferably 9~11h.

[0028] In this invention, the mass concentration of the oxalic acid solution is 1-2%, preferably 1.2-1.8%, and more preferably 1.4-1.6%.

[0029] In this invention, the reaction time in the oxalic acid solution is 12-36 hours, preferably 14-34 hours, and more preferably 16-32 hours.

[0030] In this invention, the purpose of adding oxalic acid is to wash away residual ferrous ions on the specimen.

[0031] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1

[0033] The specimen was rinsed in water to remove residual formaldehyde solution, resulting in a clean specimen. The clean specimen was then placed in a 13 g / L ferrous sulfate solution. To prevent hydrolysis of the ferrous sulfate, citric acid was added to adjust the pH to 5.5, and the reaction proceeded. After 7 hours, the reaction was complete. The specimen was removed and drained. The dried specimen was then placed in a 7% hydrogen peroxide solution, and anhydrous sodium carbonate was added to adjust the pH to 7.5. After complete dissolution, 0.5% sodium silicate was added, and the reaction continued at pH 10.5 for 10 hours. The specimen was then removed and drained. Finally, the specimen was placed in a 1.5% oxalic acid solution to remove excess Fe. 2+ The reaction ends after 24 hours. When the sample is close to milky white, remove it and rinse it with water.

[0034] The specimens processed in Example 1 have uniform color, no structural damage, and clear structural layers, making them suitable for teaching demonstrations.

[0035] Example 2

[0036] The specimen was rinsed in water to remove residual formaldehyde solution, resulting in a clean specimen. The clean specimen was then placed in a 15 g / L ferrous sulfate solution. To prevent hydrolysis of the ferrous sulfate, citric acid was added to adjust the pH to 5.0, and the reaction proceeded. After 8 hours, the reaction was complete. The specimen was removed and drained. The dried specimen was then placed in an 8% hydrogen peroxide solution, and anhydrous sodium carbonate was added to adjust the pH to 7.0. After complete dissolution, 1% sodium silicate was added, and the reaction continued at pH 10.8 for 12 hours. The specimen was then removed and drained. Finally, the specimen was placed in a 2% oxalic acid solution to remove excess Fe. 2+ The reaction ends after 20 hours. When the sample is close to milky white, remove it and rinse it with water.

[0037] Example 3

[0038] The specimen was rinsed in water to remove residual formaldehyde solution, resulting in a clean specimen. The clean specimen was then placed in a 10 g / L ferrous sulfate solution. To prevent hydrolysis of the ferrous sulfate, citric acid was added to adjust the pH to 6.0, and the reaction proceeded. After 6 hours, the reaction was complete. The specimen was removed and drained. The dried specimen was then placed in a 7% hydrogen peroxide solution, and anhydrous sodium carbonate was added to adjust the pH to 8.0. After complete dissolution, 0.5% sodium silicate was added, and the reaction continued at pH 10.2 for 8 hours. The specimen was then removed and drained. Finally, the specimen was placed in a 1% oxalic acid solution to remove excess Fe.2+ The reaction ends after 30 hours. When the sample is close to milky white, remove it and rinse it with water.

[0039] Comparative Example 1

[0040] The difference between Comparative Example 1 and Example 2 is that Comparative Example 1 directly immersed the specimen in hydrogen peroxide solution.

[0041] Comparative Example 2

[0042] Compared with Example 1, the difference is that in Comparative Example 2, the specimen was immersed in a 0.5% potassium permanganate solution for 12 hours, rinsed, immersed in a 1% oxalic acid solution for 8 hours, rinsed again, and then immersed in a 6% hydrogen peroxide solution for 24 hours.

[0043] Comparative Example 3

[0044] Compared with Example 1, the difference is that sodium silicate was not added in Comparative Example 3.

[0045] As shown in the examples and comparative examples, hydrogen peroxide without sodium silicate is acidic, and its bleaching effect is poor under acidic conditions. Extending the soaking time to improve the bleaching effect will damage the specimen structure. Conversely, adding sodium silicate not only puts the hydrogen peroxide under optimal bleaching conditions, but also provides stability to the hydrogen peroxide, reduces the decomposition rate of hydrogen peroxide, and thus improves the bleaching performance.

[0046] As can be seen from the above embodiments, the present invention provides a bleaching method for specimens with hydroxyheme deposition caused by formaldehyde oxidation, comprising the following steps: sequentially immersing the specimen in ferrous sulfate solution, hydrogen peroxide solution, and oxalic acid solution for reaction; wherein the specimen is a specimen with hydroxyheme deposition caused by formaldehyde oxidation. The present invention fundamentally alters the chemical properties of the pigment by forming a stable complex between the ferrous ions in ferrous sulfate and the heme pigment ions, making it easier to be decomposed and removed by subsequent hydrogen peroxide, ultimately resulting in a specimen color closer to the ideal milky white.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A bleaching method for a sample containing hydroxyheme deposited due to formaldehyde oxidation, characterized in that, Includes the following steps: The specimen is then sequentially immersed in ferrous sulfate solution, hydrogen peroxide solution, and oxalic acid solution to carry out the reaction. The specimen was a sample of hydroxyheme deposition caused by formaldehyde oxidation.

2. The bleaching method for a sample containing hydroxyheme deposited due to formaldehyde oxidation according to claim 1, characterized in that, The concentration of the ferrous sulfate solution is 10~15 g / L.

3. The bleaching method for specimens containing hydroxyheme deposited due to formaldehyde oxidation according to claim 1 or 2, characterized in that, The pH of the ferrous sulfate solution is 5-6, and citric acid is used to adjust the pH.

4. The bleaching method for a sample containing hydroxyheme deposited due to formaldehyde oxidation according to claim 3, characterized in that, The reaction time in ferrous sulfate solution is 6-8 hours.

5. The bleaching method for a sample containing hydroxyheme deposited due to formaldehyde oxidation according to claim 4, characterized in that, The mass concentration of the hydrogen peroxide aqueous solution is 6-8%; The pH of the hydrogen peroxide solution is 7-8, and the reagent used to adjust the pH is anhydrous sodium carbonate.

6. The bleaching method for a sample containing hydroxyheme deposited due to formaldehyde oxidation according to claim 5, characterized in that, The hydrogen peroxide solution also contains sodium silicate at a mass concentration of 0.5-1%; After adding sodium silicate, the pH of the hydrogen peroxide solution is 10-11.

7. The bleaching method for specimens containing hydroxyheme deposited due to formaldehyde oxidation according to claim 5 or 6, characterized in that, The reaction time in hydrogen peroxide solution is 8-12 hours.

8. The bleaching method for a sample containing hydroxyheme deposited due to formaldehyde oxidation according to claim 7, characterized in that, The oxalic acid solution has a mass concentration of 1-2%.

9. The bleaching method for a sample containing hydroxyheme deposited due to formaldehyde oxidation according to claim 8, characterized in that, The reaction time in oxalic acid solution is 12-36 hours.

Images