Blood trace developing agent as well as developing method and application thereof

Abstract

The invention relates to the technical field of blood trace detection, in particular to a blood trace developing agent as well as a developing method and application thereof. The blood trace developing agent comprises a disperse dye and a solvent, the concentration of the disperse dye is 2-4%, and the solvent is water, methanol, absolute ethyl alcohol, a mordant aqueous solution, a glacial acetic acid aqueous solution, a glacial acetic acid and methanol mixed solution, a glacial acetic acid and ethanol mixed solution or a dispersant and mordant mixed aqueous solution. The blood trace developing agent provided by the invention is wide in application range, blood traces on various different types of objects can be developed, developed blood fingerprint streaklines are coherent and high in definition, object backgrounds are not stained or slightly stained, the contrast between the streaklines and the backgrounds is large, and the blood trace developing agent has a good developing effect.

Description

Technical Field

[0001] The present invention relates to the technical field of trace detection, and more particularly to a blood trace revealing agent, a revealing method and an application thereof. Background Art

[0002] Latent fingerprints and bloodstains are common traces found at crime scenes, accounting for approximately 60% of such traces. Tetramethylbenzidine and amido black 10B are two traditional methods for revealing latent fingerprints and bloodstains. The former, in addition to its short lifespan and high cost, is also known to cause cancer. The latter, containing methanol and glacial acetic acid, has a strong pungent odor and is highly toxic to the user's nervous system. Furthermore, both methods are cumbersome to use, requiring the trace to be fixed before revealing, making the technique difficult to master. Newer methods include the luminol method, the fluorescent yellow method, and the indanedione method. These methods utilize the fluorescent properties of the revealing reagents, which emit strong fluorescence under illumination to enhance the contrast between bloodstains and the background. However, these methods are not only cumbersome to use, but also utilize organic solvents. During use, the fluorescent reagents themselves, their solvents, and the harmful excitation light sources can pose significant risks to the user. The harm caused to users by traditional and new blood fingerprint and blood stain revealing methods has become a helpless situation. The personal health of users can only be sacrificed in exchange for the normal progress of on-site investigation work. The complexity of the operation and the toxicity of the materials of traditional and new blood fingerprint and blood stain revealing methods have seriously restricted their application in on-site blood stain revealing and fixing. Therefore, it is urgently needed to develop a series of reagents with no toxic effects, a wide range of applicable objects and good revealing effects to replace the original toxic and limited blood stain revealing reagents, fundamentally solve the above problems, and allow users to eliminate their concerns and use them boldly. The present invention is a series of reagents that meet this expectation. Summary of the Invention

[0003] In order to solve the deficiencies in the above-mentioned background technology, the present invention provides a blood stain revealing agent and a revealing method and application thereof, and prepares a series of water-soluble non-toxic blood stain revealing fixatives.

[0004] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A first aspect of the present invention provides a use of a disperse dye in blood stain detection.

[0006] In a preferred embodiment, the use of the disperse dye in blood stain detection includes any one or more of the following:

[0007] 1) Used for blood stain visualization;

[0008] 2) Used to fix blood stains.

[0009] The second aspect of the present invention provides a blood stain revealing agent, comprising a disperse dye and a solvent; the concentration of the disperse dye is 2% to 4%, and the solvent is one of water, methanol, anhydrous ethanol, a mordant aqueous solution, a glacial acetic acid aqueous solution, a glacial acetic acid-methanol mixture, a glacial acetic acid-ethanol mixture, and a dispersant-mordant mixed aqueous solution.

[0010] In a preferred embodiment, the disperse dye is selected from one or more of disperse pink, disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse snow blue and disperse bright red.

[0011] In a preferred embodiment, the solvent is a mixed aqueous solution of a dispersant and a mordant, the concentration of the mixed aqueous solution of the dispersant and a mordant is 3%, and the mass ratio of the dispersant to the mordant is 1:9.

[0012] In the preferred embodiment, the dispersant is Lakai powder BX and the mordant is Peregal O.

[0013] A third aspect of the present invention provides a blood stain visualization method based on the above-mentioned blood stain visualization agent, comprising the following steps:

[0014] Place the object with blood stains at an angle, take the above blood stain revealing agent and evenly drop it onto the blood stains, leave it on for 1-2 minutes, rinse the object with water, and blow dry;

[0015] The object is a non-permeable object 、 semipermeable object or permeable object;

[0016] When the object is a permeable object, the permeable object is soaked in the blood stain developer for 5 to 10 seconds before the blood stain developer is added.

[0017] In a preferred embodiment, the non-permeable objects or semi-permeable objects include ceramic tiles, glass, aluminum alloy, PVC boards, plastic sheets, floor coverings and painted wood, etc.; the permeable objects include printing paper, kraft paper, natural wood and textiles, etc.

[0018] A fourth aspect of the present invention provides a blood stain detection kit comprising at least:

[0019] Solvent 5~20mL / portion

[0020] Disperse dye 0.15~0.6g / portion

[0021] Among them, the solvent is a mixed aqueous solution of dispersant and mordant, the dispersant is Lakai powder BX, the mordant is Pingpingjia O, the solution concentration of the solvent is 3%, and the mass ratio of the dispersant and the mordant is 1:9; the disperse dyes include one or more of disperse pink, disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse snow blue and disperse bright red.

[0022] Beneficial effects of the present invention

[0023] The series of water-soluble, non-toxic bloodstain revealing and fixing agents of the present invention are used to reveal and fix bloodstains on the surfaces of non-permeable objects, semi-permeable objects, and permeable objects commonly found at the scene. This series of reagents has rich and bright colors, is applicable to a wide range of objects, has a good bloodstain revealing effect, is easy to operate, and is easy to carry. This new technology creatively dissolves dyes in non-toxic solvents such as water to prepare bloodstain revealing reagents, creating a precedent for the research and development of "green reagents." Compared with other bloodstain revealing reagents, its particularly outstanding advantages are the reagent's high efficiency, safety, and reliability. It is non-toxic to both the user and the object and environment where the trace is left. The developers provided by the present invention are all excellent, green, and environmentally friendly on-site bloodstain revealing and fixing reagents. The promotion of this new technology will replace the use of traditional toxic trace revealing methods, stimulate the enthusiasm of grassroots trace detection personnel, and improve work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a dispersed pink developer that reveals the blood fingerprint effect on the color plate.

[0025] Figure 2 It is a disperse green developer that shows the blood fingerprint effect on the color plate.

[0026] Figure 3 A 3% concentration of dispersed navy blue dispersant mordant solution shows the effect of fresh blood fingerprints; object A is a tile, object B is painted wood, object C is aluminum alloy, and object D is a plastic sheet.

[0027] Figure 4 The 3% concentration of disperse snow blue dispersant mordant solution shows the effect of old blood fingerprints; object A is a plastic sheet, object B is a PVC board, object C is painted wood, and object D is glass.

[0028] Figure 5 It is the effect of dispersing bright red developer to reveal blood fingerprints on permeable objects; object A is printing paper, object B is kraft paper, object C is natural wood, and object D is textile.

[0029] Figure 6 It is a dispersed black developer that reveals the blood fingerprint effect on a permeable object; object A is printing paper, object B is kraft paper, object C is natural wood, and object D is textile.

[0030] Figure 7 This is a comparison of the effects of disperse dye developer (top) and Coomassie Brilliant Blue (bottom) in visualizing blood fingerprints; object A is ceramic tile, and the disperse dye is disperse green; object B is glass, and the disperse dye is disperse pink.

[0031] Figure 8 This is a comparison of the effects of disperse dye developer (top) and DFO (bottom) in visualizing blood fingerprints; object A is printing paper, and the disperse dye is disperse navy blue; object B is kraft paper, and the disperse dye is disperse pink; object C is textile, and the disperse dye is disperse snow blue. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0033] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. The experimental methods in the examples are conventional methods unless otherwise specified. Where specific conditions are not specified in the examples, the experiments were carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, for which the manufacturer is not specified, are all commercially available conventional products.

[0034] Because disperse dyes have similar but not identical chemical compositions and physical properties, the solubility and optimal solvents for each color also vary. To find the optimal solvent and concentration for each dye, solvent screening and formulation testing are required for each dye in the series.

[0035] After preliminary screening, this experiment selected nine disperse dyes: disperse pink, disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse snow blue, and disperse bright red as the experimental dyes. Distilled water, methanol, anhydrous ethanol, aqueous glacial acetic acid, a glacial acetic acid-methanol mixture, a glacial acetic acid-ethanol mixture, and a dispersant-mordant mixture were selected as the experimental solvents. An impermeable object was selected as the experimental object. The dispersant used in the examples of the present invention was Lakai powder BX, and the mordant was mordant peregal O.

[0036] Example 1: Preparation of Dispersed Pink Blood Stain Visualizers with Various Solvents at Different Concentrations

[0037] Add disperse pink powder to the solvent and slowly stir until fully dissolved to obtain a disperse pink blood stain visualizer (hereinafter referred to as disperse pink visualizer). Prepare disperse pink visualizers in various solvents at varying concentrations using the aforementioned method. Because disperse dyes are nonionic dyes with low water solubility, their solubility is relatively low. Preliminary testing indicates that a concentration of 4% is essentially saturated; higher concentrations will result in precipitation, so 1% was chosen as the baseline concentration. Distilled water, methanol, anhydrous ethanol, a mordant aqueous solution (3%), a glacial acetic acid aqueous solution (acetic acid and water volume ratio = 1:9), a glacial acetic acid-methanol mixture (acetic acid and methanol volume ratio = 1:9), a glacial acetic acid-ethanol mixture (acetic acid and ethanol volume ratio = 1:9), and a dispersant-mordant aqueous solution (3% concentration, dispersant and mordant mass ratio = 1:9) were selected as experimental solvents, with 10 parts of each solvent and a volume of 10 mL per part. The amount of dispersed pink added was 0.05g, 0.1g, 0.15g, 0.2g, 0.25g, 0.3g, 0.35g, 0.4g, 0.45g, and 0.5g, respectively. Different weights of dispersed pink powder were dissolved in the above solvents, and the dispersed pink developer in different solvent concentrations was labeled. The specific labeling is shown in Table 1 below.

[0038] Table 1 Marking of dispersed pink developer in various solvents at different concentrations

[0039]

[0040] In Table 1, A1 is used as an example. A1 represents a dispersed pink developer obtained by dissolving 0.05 g of dispersed pink powder in water as a solvent. The rest of the labels are similar and will not be described in detail.

[0041] Example 2: Testing the effect of dispersed pink developer

[0042] Object selection

[0043] The color development effects of 80 dispersed pink developers prepared in Example 1 were tested using seven materials, namely ceramic tiles, glass, aluminum alloy, PVC board, plastic sheet, floor leather and painted wood, as objects.

[0044] Testing Process

[0045] Bloody fingerprints were made on each of the seven objects described above. Each of the objects and the dispersed pink developer prepared in Example 1 were placed on a workbench. Label each object, noting the development conditions. The object was held with tweezers and tilted. The dispersed pink developer was pipetted with a pipette and evenly dripped onto the fresh bloody fingerprint. After the specimen dried, it was rinsed with detergent to remove any excess dispersed pink developer from the lines and the object background. After rinsing, the specimen was dried with a hair dryer and photographed.

[0046] Test results

[0047] Disperse pink was dissolved in various solvents at varying concentrations to reveal bloody fingerprints on various objects. The results showed that disperse pink had better solubility in water, methanol, and mordant than in other solvents. Among the 3% disperse pink solutions prepared in the eight solvents mentioned above, disperse pink in water, disperse pink in methanol, disperse pink in mordant, and disperse pink in dispersant-mordant water showed the best solubility. The solutions in the other solvents were nearly saturated at 2% disperse pink. Disperse pink dissolved quickly in water, mordant, and dispersant-mordant, taking only 1-2 minutes, while it took 5-6 minutes in the other solvents.

[0048] By comparing the visualization effects of various concentrations and solvents, it can be found that the blood fingerprint lines displayed by the 3% disperse pink dispersant mordant solution on the above seven objects are continuous and clear, the object background is not stained or slightly stained, the contrast between the lines and the background is large, and the visualization effect is the best.

[0049] Example 3: Preparation of a series of disperse dye developers in various solvents with different concentrations

[0050] A series of disperse dye developers with different concentrations of various solvents were prepared according to the method of preparing disperse pink developers with different concentrations of various solvents in Example 1. Unlike Example 1, eight different disperse dye colors, namely disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse snow blue, and disperse bright red, were selected as the dispersion medium; some of the solvents used in Example 1 were selected as experimental solvents, and the selected solvents were methanol, mordant, glacial acetic acid methanol (glacial acetic acid: methanol = 1:9), and a dispersant-mordant mixed hydrate solution (dispersant: mordant = 1:9). A total of 320 disperse dye developers were prepared.

[0051] Example 4: Testing of the Development Effect of Disperse Dye Developers in Various Solvents with Different Concentrations

[0052] This embodiment uses the same objects and testing procedures as in Embodiment 2 to conduct development tests on 320 series of disperse dye developers in various solvents with different concentrations configured in Example 3.

[0053] This embodiment is based on the best formula of disperse pink, and uses a series of disperse dyes of different colors, namely disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse snow blue and disperse red (a total of 8 kinds) as dispersion media, and selects methanol, mordant, glacial acetic acid methanol (glacial acetic acid: methanol = 1:9), and dispersant mordant mixed solution (dispersant: mordant = 1:9) as screening experimental solvents for disperse dyes, and selects 2% to 4% as the experimental concentration range. Compare the fingerprint visualization effects of different solvents and different concentrations of dyes. The experimental results show that the solubility of the eight disperse dyes selected in the experiment in the same solvent is not the same, but the best visualization effect is achieved by a developer with a concentration of 3% and a dispersant mordant mixed aqueous solution as the solvent. Among them, Figure 3 A 3% concentration of dispersed navy blue dispersant mordant solution shows the effect of fresh blood fingerprints.

[0054] Based on the comparative discussion of the above results, the optimal solvent and optimal concentration of nine disperse dyes were selected. Finally, it was determined that the dispersant-mordant mixed aqueous solution (dispersant: mordant = 1:9) was the optimal solvent for disperse dyes, and 3% was the optimal concentration.

[0055] Example 5: Determination of flushing agent and flushing method

[0056] Through the above experiments, it has been determined that a 3% disperse dye dispersant mordant mixed aqueous solution is the best developer, but the development effect of the disperse dye is also related to the flushing operation. If the flushing is not strong enough, it is easy to cause the background coloring to be too dark and cannot be rinsed clean, and the contrast with the traces is difficult to distinguish; if the flushing is improper, it is easy to cause the blood fingerprint to be light in color, and the blood fingerprint will diffuse after it is developed, affecting the effect.

[0057] Choice of flushing agent

[0058] Distilled water, methanol, anhydrous ethanol, mordant and dispersant-mordant mixed aqueous solution (concentration 3%, dispersant: mordant = 1:9) were selected as experimental flushing agents.

[0059] Choice of flushing method

[0060] In the experiment of protein staining to visualize blood fingerprints, there are two common rinsing methods: one is to rinse first and then blow dry, and the other is to blow dry first, then rinse, and finally blow dry. To screen the best rinsing method, this example uses the above two rinsing methods to compare the visualization effects.

[0061] In the following, for the convenience of expression, the flushing method is defined as follows:

[0062] Rinse method a: rinse first after dripping the developer (to the extent that the background is rinsed clean) and then blow dry;

[0063] Rinse method b is to blow dry after applying the developer, then rinse (until the background is rinsed clean), and finally blow dry again.

[0064] The five aforementioned rinse agents and different rinse processes were screened to determine the optimal rinse agent and rinse method. To reduce the experimental repetition rate and simplify the experimental operation process, Disperse Pink Developer was selected as the developer for this experiment. According to the basic experimental operation method, 3% Disperse Pink Dispersant Mordant Developer was used to visualize fresh blood fingerprints on tiles under the same conditions. Different rinse agents and different rinse processes were used for rinsing.

[0065] The same method as above was used to reveal fresh blood fingerprints on glass, aluminum alloy, PVC board, plastic sheet, floor leather and painted wood.

[0066] The experimental results show that using a mixture of water and a dispersant-mordant solution as a rinse agent after development, followed by air drying, results in well-developed handprints with no diffusion, clear lines, and high contrast. Water is the most environmentally friendly, inexpensive, and readily available rinse agent. Therefore, water is the optimal rinse agent for dispersing pink to reveal bloody handprints, and air drying after rinsing is the optimal rinse method.

[0067] Verification experiment

[0068] The above screening experiments ultimately showed that water was the best rinse agent for dispersing pink to reveal blood fingerprints, and rinse method a was the best rinse method. In order to test whether this rinse agent and rinse method are applicable to the rinse operation after the visualization of other colors of disperse dyes, a verification experiment was performed on the lower half of the object.

[0069] Prepare 3% concentrations of Disperse Green, Disperse Grass Green, Disperse Light Yellow, Disperse Lake Blue, Disperse Navy Blue, Disperse Black, Disperse Snow Blue, and Disperse Bright Red (disperse mordant to developer ratio of 1:9). Following the basic blood fingerprint visualization procedure, visualize fresh blood fingerprints on non-permeable surfaces such as ceramic tiles. After visualization, rinse with water, then blow dry. After visualization and rinsing, photograph and record the visualization results.

[0070] The experimental results show that a series of disperse dyes, using water as the rinse agent and rinsing followed by air drying as the post-development rinse method, are highly effective in visualizing fresh blood fingerprints on non-permeable objects. After rinsing, the fingerprint lines are clear, with no fading, no adhesion, no diffusion, high contrast, and minimal or no background staining. Through experimental screening and verification, water is determined to be the optimal rinse agent for disperse dye-based blood fingerprint visualization, and rinsing followed by air drying is the optimal rinse method.

[0071] Example 6: Study on the method of revealing permeable objects

[0072] Previous experiments have identified the optimal solvent and concentration, as well as the optimal rinse agent and method, for using disperse dyes to visualize blood fingerprints on non-permeable objects. Disperse dyes are not prone to staining the background of non-permeable objects, allowing for direct visualization.

[0073] Because disperse dyes easily stain fibers and textiles, when revealing non-permeable objects such as printing paper, kraft paper, and bloody fingerprints on textiles, the object background is easily stained by disperse dyes. To prevent staining of the object background, pretreatment is required before visualization.

[0074] In order to expand the application range of disperse dye development method and find a development method for blood fingerprints on permeable objects using disperse dye, it is necessary to determine the best development method for blood fingerprints on permeable objects using disperse dye through experimental screening.

[0075] Combining the anti-diffusion treatment methods used in conventional development methods with the unique physical and chemical properties of disperse dyes, and based on the development characteristics of disperse dye development methods and the characteristics of the solvent, a simple preliminary experiment screened the following pretreatment methods: hydrogen peroxide rinse, rinse with an anhydrous ethanol-hydrogen peroxide mixture (ethanol:hydrogen peroxide = 1:1), hydrogen peroxide immersion, distilled water immersion, mordant immersion, and dispersant-mordant immersion (dispersant:mordant = 1:9). These methods are designated as Pretreatment Method a, Pretreatment Method b, Pretreatment Method c, Pretreatment Method d, Pretreatment Method e, and Pretreatment Method f.

[0076] Screening of pretreatment methods

[0077] A series of disperse dyes share similar physical and chemical properties and require similar pretreatment methods for visualizing bloody fingerprints on permeable objects. In a screening experiment for the optimal pretreatment method, disperse pink was selected as the visualizing agent, and validation experiments were conducted using the remaining eight disperse dyes.

[0078] Prepare a 3% concentration of Disperse Pink dispersant, mordant (dispersant:mordant = 1:9) and developer. Before development, treat fresh blood fingerprints on permeable surfaces using pretreatment methods a, b, c, d, e, and f. The permeable surfaces used were: printer paper, kraft paper, natural wood, and textiles. After development, each surface was labeled and photographed.

[0079] The experimental results show that the best visualization effect is achieved after pretreatment using method f (dispersant mordant immersion method). Four objects, namely printing paper, kraft paper, natural wood and textiles, were immersed in a dispersant mordant mixture, with immersion times of 1 second, 3 seconds, 5 seconds, 10 seconds, 15 seconds, 30 seconds and 60 seconds respectively. The blood fingerprints on the immersed objects were visualized one by one using 3% disperse pink dispersant mordant developer, and the best immersion time was selected by comparing the visualization results. Among them, the effects of disperse bright red developer and disperse black developer on visualizing blood fingerprints on permeable objects are as follows: Figures 5-6 shown.

[0080] The experimental results show that before revealing blood fingerprints with a disperse pink dispersant-mordant solution, soaking the object in a mixture of dispersant and mordant before revealing them results in clear lines on the permeable object, no adhesion, no fading, and no diffusion. The object is not stained or is only slightly stained, which does not affect the revealing effect. Several other pretreatment methods all damage the lines of the handprints to varying degrees, staining the object to varying degrees, affecting the revealing effect. Finally, soaking the object in a mixture of dispersant and mordant (dispersant: mordant = 1:9) for 5 to 10 seconds is determined to be the optimal pretreatment method for revealing blood fingerprints on permeable objects with disperse dyes.

[0081] Verification experiment

[0082] The above experiments have screened out the best pretreatment method for dispersing pink to reveal blood fingerprints on permeable objects. In order to test whether this method is applicable to other series of dyes, verification experiments are needed.

[0083] Disperse Green, Disperse Grass Green, Disperse Light Yellow, Disperse Lake Blue, Disperse Navy Blue, Disperse Black, Disperse Snow Blue, and Disperse Red were selected as reagents for the experiment. A series of disperse dyes, dispersant, and mordant solutions (dispersant:mordant = 1:9) were prepared at a 3% concentration. Using the optimal pretreatment method identified in previous experiments, bloody handprints on printing paper, kraft paper, natural wood, and textiles were treated. The treated bloody handprints were then developed using a series of disperse dye solutions. After development, photographs were taken and recorded.

[0084] The experimental results show that the disperse dye series using a pretreatment method of soaking the object with a dispersant and mordant all have good results in revealing blood fingerprints on permeable objects. For blood fingerprints on printing paper, kraft paper, and natural wood, the lines are clearly visible and the background is slightly stained.

[0085] Disperse dyes are primarily used in the chemical industry for dyeing polyester and its blends. They offer a strong dyeing effect on textiles, resulting in rapid, durable dyeing. Therefore, when using disperse dye solutions to visualize bloody fingerprints on textiles, anti-guest dyeing treatment is essential, as otherwise the textile will be stained. After soaking the textile in a dispersant mordant, developing it with a disperse dye developer results in excellent results, with clear lines and minimal staining.

[0086] Through screening and validation experiments, it was determined that soaking the permeable object in a mixture of dispersant and mordant (dispersant:mordant = 1:9) for 5 to 10 seconds was the optimal pretreatment method for permeable objects. This method was used to visualize bloody fingerprints on permeable objects, achieving excellent results using disperse dyes.

[0087] Example 7: Sensitivity test of disperse dye developer

[0088] Through a series of experiments, the optimal formulation for the developer was determined to be a 3% dispersant pink dispersant mordant, water as the optimal rinse agent, air drying after rinsing as the optimal rinse process, and immersion in a penetrating solvent as the pretreatment method. However, to further analyze and investigate the practical applicability of this developer in real-world settings, the sensitivity of this method was tested on blood fingerprints diluted to various concentrations, allowing for a comprehensive, objective, and accurate assessment of the effectiveness of the new development method.

[0089] Sensitivity test of disperse pink developer

[0090] Imprint the desired blood fingerprints, as well as several blood fingerprints diluted with water to concentrations of 50%, 20%, 10%, 5%, 2%, and 1%, on ceramic tiles, glass, plastic sheets, aluminum alloy, PVC board, printer paper, and natural wood. Follow the basic development process with a 3% dispersant pink dispersant and mordant developer. Before developing the blood fingerprints on the printer paper and natural wood, soak the object in the dispersant-mordant mixture for 5 seconds to prevent the blood stain from spreading and staining the object. Take photos and record the results immediately after development.

[0091] From the results, it can be seen that the sensitivity of 3% disperse pink dispersant mordant developer is good, and it can also have a good display effect on blood fingerprints diluted to 5%, especially for blood fingerprints on smooth and non-permeable objects such as tiles, glass, plastic sheets, aluminum alloys, PVC boards, etc. The displayed fingerprints have good dyeing effect, clear lines and large contrast; however, when the concentration is lower than 2%, the display effect on various objects is very poor. This is because the dyeing ability of any dye has a certain limit, and it can only have a good effect within a certain range. When the concentration of blood fingerprints is too low, that is, below 2%, the display effect of disperse pink is very poor.

[0092] Verification experiment

[0093] The sensitivity test of the disperse pink developer has confirmed the sensitivity of the disperse pink developer. A 3% disperse pink dispersant mordant developer can also effectively visualize blood fingerprints diluted to 5%, with good dyeing, clear lines, and high contrast. However, at concentrations below 2%, visualization is poor. This part of the experiment will test the visualization effect of other series of dyes on blood fingerprints diluted to a concentration of 5% to determine the sensitivity of disperse dyes in visualizing blood fingerprints.

[0094] Several bloody fingerprints were printed on ceramic tiles, glass, plastic sheets, aluminum alloy, PVC board, printer paper, and natural wood. Following the basic development process, these fingerprints were developed using a 3% concentration of a series of disperse dyes, a dispersant, a mordant, and a developer. For the bloody fingerprints on printer paper and natural wood, treatment was performed before development to prevent the blood from spreading and staining the object. After development, photographs were taken and recorded promptly.

[0095] From the results, it can be seen that the series of disperse dyes, dispersants, mordants and developers with a concentration of 3% have a good visualization effect on blood fingerprints diluted to a concentration of 5%. The displayed fingerprints have good dyeing effect, clear lines, large contrast, no diffusion of blood stains, and no staining or slight staining of the object.

[0096] Example 8: Study on the Time-Effectiveness of Disperse Dye Developer

[0097] Examples 1-7 primarily involved solvent screening, formulation determination, flushing agent and flushing method research, and penetrating object visualization. These experiments revealed fresh bloody fingerprints, but bloody fingerprints left at crime scenes are often not fresh. To test the effectiveness of disperse dye developers on older bloody fingerprints, a study on the timeliness of disperse dye developers was necessary.

[0098] Old blood fingerprint production

[0099] Several bloody fingerprints were placed on ceramic tiles, glass, plastic sheets, aluminum alloy, PVC boards, artificial leather, kraft paper, printer paper, and natural wood at different times, with the time intervals from the development experiment being 6 months, 3 months, 2 months, 1 month, 20 days, 10 days, 5 days, 3 days, 2 days, and 1 day. The bloody fingerprints were stored in a cool, dry place.

[0100] Experimental operation

[0101] A number of bloody fingerprints on various objects with different stamping times of 1 day, 2 days, 3 days, 5 days, 10 days, 20 days, 1 month, 2 months, 3 months, 6 months, and just after were selected. The fingerprints were developed in sequence using a 3% concentration of disperse pink dispersant, mordant, and developer according to the basic operating method.

[0102] The experimental results show that the developing effect of the 3% disperse pink dispersant mordant developer is little affected by the time the blood fingerprints are left, and it can also have a good effect on blood fingerprints that have been left for 6 months. This is because protein has strong stability under normal circumstances. As long as the blood fingerprints are not corrupt, even if they are left for a long time, they can be successfully revealed by simply extending the development time appropriately or repeating the development several times to allow the reagent to penetrate the blood stains.

[0103] Verification experiment

[0104] A 3% concentration of disperse pink dispersant mordant developer has a good effect on six-month-old blood fingerprints. In order to test the effect of a series of disperse dyes on the visualization of old blood fingerprints and to determine the timeliness of disperse dye developers, a verification experiment is required.

[0105] Several old bloody fingerprints left on various objects for six months were selected and developed using 3% concentrations of disperse green, disperse grass green, disperse light yellow, disperse lake blue, disperse navy blue, disperse black, disperse snow blue, and disperse bright red dispersant mordant developer. Pretreatment is required before developing permeable objects.

[0106] Through the timeliness verification experiment of the series of disperse dyes, it was found that the series of disperse dyes have a wide range of timeliness, and can still show a good effect on the old blood fingerprint left for 6 months. Disperse dyes can show fresh to old blood fingerprints. Among them, the effect of 3% concentration of disperse snow blue dispersant mordant solution on showing old blood fingerprints is as follows Figure 4 shown.

[0107] Example 9: Stability test of developer

[0108] Due to the low solubility of disperse dyes, disperse dye developers may precipitate after prolonged storage, which can affect the development effect. To determine the stability of the developer and the optimal storage method, a stability test was conducted on a 3% concentration of disperse pink dispersant mordant developer.

[0109] Experimental operation

[0110] Prepare 8 10ml portions of 3% Disperse Pink Dispersant Mordant Developer every 1 to 10 days. Store sealed in a cool, dry place at room temperature. Follow the basic blood fingerprint visualization procedures to visualize blood fingerprints on different objects using freshly prepared 3% Disperse Pink Dispersant Mordant Developer and those stored for 1, 2, 3, 5, 10, 15, 20, and 30 days.

[0111] The experimental results show that 3% disperse pink dispersant mordant developer can be stored for a long time under sealed conditions without deterioration and without affecting the developing effect. This is mainly because the solution is stable, the dispersant and mordant do not react with air components, and are not greatly affected by temperature and humidity, so they can be stored for a long time.

[0112] Verification experiment

[0113] The above experiments confirmed that the dispersed pink developer has good stability and can be stored for a long time. In order to test the stability of the series of dyes, a verification experiment of the stability of the series of dyes was carried out.

[0114] Following the basic preparation method for disperse dye developers, a series of disperse dye dispersant and mordant developers were prepared at 3% concentration in different time periods. Store in a cool, dry place at room temperature. A series of dye developers, stored for 30 days, was used to develop fresh blood fingerprints on various objects. Before developing permeable objects, treatment was performed to prevent blood staining and staining. After development, photographs were taken and recorded promptly. The results are shown in Table 2.

[0115] The experimental results show that the 3% series of disperse dyes, dispersants, mordants and developers have good stability and can be stored for a long time under sealed conditions without deterioration, precipitation, and affecting the development effect.

[0116] Table 2 The effect of a series of dye developers on the appearance of fresh blood fingerprints on different objects after storage for 30 days

[0117]

[0118]

[0119] Note: ① "+++" indicates that the fingerprint lines are continuous and clear, the object background is not stained or slightly stained, and the contrast is large; ② "++" indicates that the fingerprint lines are relatively continuous and clear, or the object background is stained to a certain extent, and the overall contrast is good; ③ "+" indicates that the fingerprint lines are poorly continuous and clear, or the object background is heavily stained and the overall contrast is weak; ④ "-" indicates that no fingerprint lines are visible.

[0120] Example 10: Study on color complementation of a series of disperse dye developers

[0121] Complementary color principle

[0122] Disperse dyes are available in a wide variety of colors. When visualizing bloody fingerprints, the appropriate dye can be selected based on the color of the object. Because disperse dyes are brightly colored, light-colored objects are not restricted by disperse dye color. For dark objects, it's important to choose an appropriate color to minimize the contrast between the fingerprint and the background. When choosing colors, consider the principle of complementary colors.

[0123] In optics, when two colors of light are mixed in appropriate proportions to produce a white sensation, they are called complementary colors, such as red and green, blue and orange, and purple and yellow.

[0124] (1) Complementary colors

[0125] Complementary colors blending together can reduce color purity, turning it gray. Complementary colors aren't generally used in painting. However, when two complementary colors occupy a larger area than the other, they can enhance contrast and make the image stand out. Generally speaking, using complementary colors has both advantages and disadvantages.

[0126] (2) Complementary colors in optics

[0127] If two colors (monochromatic or polychromatic) are mixed in appropriate proportions to produce the perception of white, they are said to be complementary. For example, red light with a wavelength of 656nm and cyan light with a wavelength of 492nm are complementary colors. Similarly, magenta and green, yellow and blue, or any of the three primary colors are complementary to the mixture of the other two. Subtracting complementary colors (such as when mixing pigments, applying two complementary colors to the same spot on white paper) creates black. When complementary colors are placed side by side, they produce a sharp contrast, with red appearing redder and green appearing greener. Reducing the saturation of complementary colors can lead to a more harmonious appearance. The color of a non-luminous object (such as a pigment) is primarily determined by its absorption and reflection of external light, so the object's color is related to the illuminating light. The color of an object under daylight is generally referred to as the object's color. If daylight shines on a surface composed of a mixture of yellow and blue, the yellow pigment reflects the red, orange, yellow, and green components of the white light, while the blue light absorbs the red, orange, and yellow components. This mixing of colors, unlike additive mixing, is called subtractive mixing. An object that completely reflects white light is called a white body; an object that completely absorbs the light is called a black body (absolute black body).

[0128] Complementary color experiment

[0129] Select a number of color plates of red, yellow, green and blue, press blood fingerprints on the color plates, and use the series of disperse dyes, dispersants, mordants and developers with a concentration of 3% prepared in Example 1 and Example 3 to develop them one by one, take pictures and record them.

[0130] From the above development effects, it can be seen that after the disperse dye developer is developed, the blood fingerprint lines are bright in color, with a large contrast to the background color, and are less affected by the background color of the object; for the blood fingerprint on the color plate of the same color as the dye, the color of the lines after development is close to the color of the object, with a small color contrast, which is not conducive to observation and photo extraction. When choosing disperse dyes to develop blood fingerprints, dyes with colors close to the background color of the object should be avoided. Figures 1-2 As shown, the blood fingerprint effect on the color plate is revealed using disperse pink developer and disperse green developer.

[0131] Comparative Example 1: Comparison between the visualization method of the present invention and the conventional visualization method

[0132] Comparison of bloody fingerprint appearance on non-permeable objects

[0133] In this experiment, the disperse dye development method was compared with the Coomassie Brilliant Blue development method and the Amino Black 10B development method. Both the Coomassie Brilliant Blue and Amino Black 10B development methods use a common technical formula.

[0134] The experimental procedures are as follows: 1) Use disperse dye development and Coomassie Brilliant Blue to visualize bloody fingerprints left on different objects. The upper half is visualized with disperse dye and the lower half with Coomassie Brilliant Blue. 2) Use disperse dye development and Amido Black 10B to visualize bloody fingerprints on different non-permeable objects. The upper half is visualized with disperse dye and the lower half with Amido Black 10B. Compare and record the fingerprint visualization results.

[0135] like Figure 7 The following figure shows a comparison of the effects of disperse dye developer (top) and Coomassie Brilliant Blue (bottom) on visualizing blood fingerprints. The experimental results show that disperse dye developer can effectively visualize blood fingerprints on non-permeable surfaces; Coomassie Brilliant Blue can also visualize blood fingerprints on various non-permeable objects. However, the solvent of Coomassie Brilliant Blue developer is a mixture of ethanol and glacial acetic acid. Ethanol is volatile, and glacial acetic acid has a pungent odor. Disperse dye solvents are non-toxic, harmless, and odorless. In terms of environmental friendliness, disperse dye developer is superior to Coomassie Brilliant Blue developer.

[0136] Compared to the disperse dye and amino black 10B development methods, both offer excellent visualization of bloody fingerprints on light-colored objects. However, when developing bloody fingerprints on dark objects, the contrast between the fingerprint lines and the background color after development with amino black 10B is low, resulting in poor visualization. Therefore, amino black 10B visualization of bloody fingerprints is significantly affected by the background color of the object, making it unsuitable for visualization of bloody fingerprints on dark objects. Disperse dye development, on the other hand, offers a range of color shades, making it suitable for visualization of both light-colored and dark-colored latent fingerprints, surpassing the amino black 10B development method in terms of applicability.

[0137] Comparison of blood fingerprint appearance on penetrating objects

[0138] There are many methods for visualizing bloody fingerprints on permeable surfaces such as white paper, silk, kraft paper, and natural wood. Commonly used methods include tetramethylbiphenyl (TMB) and DFO. This study primarily uses these two methods for comparative study with disperse dye visualization. Both TMB and DFO utilize a common formulation.

[0139] The experimental process is as follows: blood fingerprints on different objects are visualized using disperse dye developer and TMB developer, the upper half of the object is visualized using disperse dye developer, and the lower half of the object is visualized using TMB developer; blood fingerprints on different objects are visualized using disperse dye developer and DFO developer, the upper half of the object is visualized using disperse dye developer, and the lower half of the object is visualized using DFO developer.

[0140] The development results show that both disperse dye and TMB methods offer excellent visualization results for bloody fingerprints on permeable surfaces, with clear lines and minimal background staining. However, bloody fingerprints on dark surfaces are difficult to visualize with TMB due to the low contrast between the background and lines.

[0141] like Figure 8 The following figure compares the effects of disperse dye developer (top) and DFO (bottom) on visualizing blood fingerprints. Disperse dye developer is superior to DFO developer in visualizing blood fingerprints. However, DFO developer is more complex and time-consuming to use.

[0142] In summary, based on the physicochemical properties of disperse dyes and utilizing the dyeing principles of disperse dyes, we conducted an in-depth analysis of their characteristics and the factors affecting solution concentration, solubility, and reaction during the preparation process. Through a series of scientific and rigorous experiments, we reached the following conclusions:

[0143] (1) A mixture of dispersant and mordant in a ratio of 1:9 is the best solvent for disperse dyes, and 3% is the optimal concentration.

[0144] (2) Water is the best rinse agent for using disperse dyes to reveal blood fingerprints. Rinse first and then blow dry is the best rinse method.

[0145] (3) Soaking the permeable object in a mixed aqueous solution of dispersant and mordant (dispersant: mordant = 1:9) for 5 to 10 seconds. This method was used to pre-treat the permeable object for revealing blood fingerprints, achieving a good visualization effect of disperse dyes on the permeable object.

[0146] (4) Disperse dyes have a good visualization effect on blood fingerprints diluted 20 times and old blood fingerprints left for 6 months.

[0147] (5) Disperse dye developer has good stability and can be stored for a long time under sealed conditions without deterioration or precipitation, which does not affect the development effect.

[0148] From the above, we can see that disperse dye developer is a new type of developer that is non-toxic, harmless, simple to prepare and easy to store; the disperse dye developer method is simple to operate and easy to rinse, and can reveal fresh and old blood fingerprints and blood traces on permeable, semi-permeable and non-permeable objects.

[0149] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. Use of a disperse dye in blood stain detection.

2. The use of disperse dyes in blood stain detection according to claim 1, characterized in that: Any one or more of the following: 1) Used for blood stain visualization; 2) Used to fix blood stains.

3. A blood stain revealing agent, characterized in that: The invention comprises disperse dyes and solvents; the concentration of the disperse dyes is 2% to 4%, and the solvent is one of water, methanol, anhydrous ethanol, mordant aqueous solution, glacial acetic acid aqueous solution, glacial acetic acid-methanol mixed solution, glacial acetic acid-ethanol mixed solution and dispersant-mordant mixed aqueous solution.

4. The blood stain revealing agent according to claim 3, characterized in that: The disperse dye is selected from one or more of disperse pink, disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse snow blue and disperse bright red.

5. The blood stain revealing agent according to claim 3, characterized in that: The solvent is a dispersant-mordant mixed aqueous solution, the concentration of the dispersant-mordant mixed aqueous solution is 3%, and the mass ratio of the dispersant to the mordant is 1:

9.

6. The blood stain revealing agent according to claim 3, characterized in that: The dispersant is Lakai powder BX, and the mordant is Peregal O.

7. A blood stain revealing method based on the blood stain revealing agent according to any one of claims 3 to 6, characterized in that: The steps include: Place the object with blood stains at an angle, take the blood stain revealing agent according to any one of claims 3 to 7 and evenly drop it onto the blood stains, keep it for 1 to 2 minutes, rinse the object with water, and blow dry; The guest is a non-permeable guest 、 semipermeable object or permeable object; When the object is a permeable object, the permeable object is soaked in the blood stain developing agent for 5 to 10 seconds before the blood stain developing agent is added dropwise.

8. The visualization method according to claim 7, wherein: The non-permeable objects or semi-permeable objects include ceramic tiles, glass, aluminum alloy, PVC boards, plastic sheets, floor coverings and painted wood; the permeable objects include printing paper, kraft paper, natural wood and textiles.

9. A blood trace detection kit, characterized in that: At least: Solvent 5~20mL / portion Disperse dye 0.15~0.6g / portion In which, the solvent is a mixed aqueous solution of dispersant and mordant, the dispersant is Lakai powder BX, the mordant is Peregal O, the solution concentration of the solvent is 3%, and the mass ratio of dispersant to mordant is 1:9; the disperse dyes include one or more of disperse pink, disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse snow blue and disperse bright red.

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