Blood trace developer and its developing method and application

Abstract

The present application relates to blood trace detection technical field, specifically relates to a kind of blood trace developing agent and its developing method and application.The blood trace developing agent of the present application includes disperse dye and solvent;The concentration of the disperse dye is 2%~4%, and the solvent is water, methanol, anhydrous ethanol, mordant aqueous solution, glacial acetic acid aqueous solution, glacial acetic acid methanol mixed solution, glacial acetic acid ethanol mixed solution or disperse agent mordant mixed aqueous solution.The blood trace developing agent provided by the present application is widely applicable, can make the blood trace on various different types of object appear, the blood handprint line of appearance is coherent, high definition, object background is not dyed or slightly dyed, line and background contrast is big, with good appearance effect best.

Description

Technical Field

[0001] This invention relates to the field of trace detection technology, and more specifically, to a bloodstain developer, its development method, and its application. Background Technology

[0002] Blood latent fingerprints and bloodstains are among the most frequently found types of crime scene traces in violent crimes, accounting for approximately 60% of such traces. Tetramethylbenzidine and Amine Black 10B are two traditional methods for developing blood latent fingerprints and bloodstains. The former, besides having a short effective time and being expensive, also has some carcinogenic effects. The latter's reagent formula contains methanol and glacial acetic acid, which not only has a strong irritating odor but is also highly toxic to the user's nervous system. Furthermore, both methods are cumbersome to use, requiring fixation of the traces before development, and the development procedures are difficult to master. Currently, newer development methods include luminol, fluorescein, and ninhydrin. These new methods utilize the fluorescent properties of the developing reagents, emitting strong fluorescence under light to enhance the contrast between the bloodstains and the background. However, these methods are not only cumbersome to use, but the solvents used are all organic solvents. During use, the fluorescent reagents themselves, their solvents, and the harmful excitation light source all cause significant harm to the user. The harm caused to users by traditional and new methods of displaying blood fingerprints and bloodstains has become an unavoidable consequence, forcing users to sacrifice their personal health in order to ensure the normal progress of on-site investigation. The complexity of operation and the toxicity of materials in traditional and new methods of displaying blood fingerprints and bloodstains have severely limited their application in the on-site display and fixation of bloodstains. Therefore, there is an urgent need to develop a series of non-toxic reagents with a wide range of applicable subjects and good display effects to replace the existing toxic and limited bloodstain display reagents, fundamentally solving the above problems and allowing users to use them with confidence without any concerns. This invention is a series of reagents that meets this expectation. Summary of the Invention

[0003] To address the shortcomings of the aforementioned background technology, this invention provides a bloodstain developing agent, its developing method, and its application, and prepares a series of water-soluble, non-toxic bloodstain developing and fixing agents.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution:

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

[0006] In the preferred embodiment, the use of the above-mentioned disperse dyes in bloodstain detection includes any one or more of the following:

[0007] 1) Used to reveal bloodstains;

[0008] 2) Used for fixing bloodstains.

[0009] In a second aspect, the present invention provides a bloodstain developer 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, an aqueous solution of mordant, an aqueous solution of glacial acetic acid, a mixture of glacial acetic acid and methanol, a mixture of glacial acetic acid and ethanol, and an aqueous solution of a mixture of dispersant and mordant.

[0010] In the 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 lilac and disperse scarlet.

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

[0012] In the preferred embodiment, the dispersant is BX (a dispersant powder) and the mordant is O (a mordant compound).

[0013] A third aspect of the present invention provides a method for developing bloodstains based on the above-described bloodstain developing agent, comprising the following steps:

[0014] Tilt the object with bloodstains and apply the above-mentioned bloodstain developing agent evenly to the bloodstains. Keep it for 1-2 minutes, rinse the object with water, and then blow it dry.

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

[0016] When the object is a permeable object, immerse the permeable object in the bloodstain developing agent for 5-10 seconds before adding the bloodstain developing agent.

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

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

[0019] Solvent 5-20 mL / part

[0020] Disperse dye 0.15–0.6 g / part

[0021] The solvent is a mixed aqueous solution of dispersant and mordant, the dispersant is BX (a dispersant powder), the mordant is O (a mordant), the solvent concentration is 3%, and the mass ratio of dispersant to mordant is 1:9. The disperse dyes include one or more of the following: disperse pink, disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse lilac, and disperse scarlet.

[0022] Beneficial effects of the present invention

[0023] This invention provides a series of water-soluble, non-toxic bloodstain development and fixation agents for developing and fixing bloodstains on common non-permeable, semi-permeable, and permeable surfaces. These reagents offer a rich and vibrant color palette, are suitable for a wide range of surfaces, provide excellent bloodstain development, are easy to use, and are portable. This innovative technology creatively dissolves dyes in water and other non-toxic solvents to formulate bloodstain development reagents, pioneering the development of "green reagents." Compared to other bloodstain development reagents, its most prominent advantages are its high efficiency, safety, and reliability. It is non-toxic to users, the surfaces where traces are left, and the environment. The development agents provided by this invention are all excellent, green, and environmentally friendly on-site bloodstain development and fixation reagents. The promotion of this new technology will replace the use of traditional toxic trace development methods, stimulating the enthusiasm of grassroots trace inspection personnel and improving work efficiency. Attached Figure Description

[0024] Figure 1 It is a dispersed pink developer used to develop the effect of bloody handprints on a color plate.

[0025] Figure 2 It is a bloody handprint effect on a developing plate using dispersed green developer.

[0026] Figure 3 The effect of a fresh blood handprint is achieved by a 3% concentration of dispersible indigo mordant solution; Object A is ceramic tile, Object B is painted wood, Object C is aluminum alloy, and Object D is plastic sheet.

[0027] Figure 4 The effect of an old bloody handprint is achieved by a 3% concentration of a dispersant mordant solution; 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 The effect of a bloody handprint on a penetrating object is achieved by using a dispersible red developer; object A is printing paper, object B is kraft paper, object C is natural wood, and object D is textiles.

[0029] Figure 6 The effect of a bloody handprint on a penetrating object is achieved by a dispersible black developer; object A is printing paper, object B is kraft paper, object C is natural wood, and object D is textiles.

[0030] Figure 7 This is a comparison of the effects of disperse dye developer (top) and Coomassie Brilliant Blue (bottom) on developing bloody handprints; Subject A is ceramic tile, disperse dye is disperse green; Subject B is glass, disperse dye is disperse pink.

[0031] Figure 8 This is a comparison of the effects of disperse dye developer (top) and DFO (bottom) on developing blood handprints; Subject A is printing paper, disperse dye is disperse navy blue; Subject B is kraft paper, disperse dye is disperse pink; Subject C is textiles, disperse dye is disperse lilac. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0033] In this invention, unless otherwise stated, scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. Unless otherwise specified, the experimental methods in the embodiments are conventional methods. Where specific conditions are not specified in the embodiments, they should be performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0034] Because the chemical composition and physical properties of a series of disperse dyes are similar but not identical, the solubility and optimal solvent for each color disperse dye also differ. To find the common optimal solvent and concentration for a series of dyes, it is necessary to conduct solvent screening and formulation determination experiments for each dye in the series.

[0035] Following 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 lilac, and disperse scarlet—as the experimental dyes. Distilled water, methanol, anhydrous ethanol, glacial acetic acid aqueous solution, a mixture of glacial acetic acid and methanol, a mixture of glacial acetic acid and ethanol, and a mixture of dispersant and mordant were selected as the experimental solvents. Non-permeable substrates were selected as the experimental substrates. In this embodiment of the invention, the dispersant used was BX (a type of dispersant powder), and the mordant was Mordant Leveling Plus O.

[0036] Example 1: Preparation of dispersible pink bloodstain developing agents with different concentrations of various solvents

[0037] Dispersed pink powder was added to the solvent and stirred slowly until fully dissolved to obtain dispersed pink bloodstain developer (hereinafter referred to as dispersed pink developer). Dispersed pink developer with different concentrations in various solvents was prepared according to the aforementioned method. Since disperse dyes are a type of nonionic dye with low water solubility, their solubility is low. Preliminary tests showed that a concentration of 4% was basically saturated; higher concentrations would result in precipitation. Therefore, 1% was selected as the baseline concentration. Distilled water, methanol, anhydrous ethanol, mordant aqueous solution (concentration 3%), glacial acetic acid aqueous solution (volume ratio of glacial acetic acid to water = 1:9), glacial acetic acid-methanol mixture (volume ratio of glacial acetic acid to methanol = 1:9), glacial acetic acid-ethanol mixture (volume ratio of glacial acetic acid to ethanol = 1:9), and dispersant-mordant mixed aqueous solution (concentration 3%, mass ratio of dispersant to mordant = 1:9) were selected as experimental solvents, with 10 portions of each solvent and 10 mL of each solvent. The amount of dispersed pink added was 0.05 g, 0.1 g, 0.15 g, 0.2 g, 0.25 g, 0.3 g, 0.35 g, 0.4 g, 0.45 g, and 0.5 g, respectively. Dispersed pink powder of different weights was dissolved in the above solvents, and the dispersed pink developer in different concentrations of solvents was labeled. The specific labeling is shown in Table 1 below.

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

[0039]

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

[0041] Example 2: Test of the development effect of dispersible pink developer

[0042] Choice of object

[0043] The color development effects of 80 dispersed pink developers prepared in Example 1 were tested on seven materials: ceramic tile, glass, aluminum alloy, PVC board, plastic sheet, linoleum, and painted wood.

[0044] Testing process

[0045] Imprint blood fingerprints onto the aforementioned seven types of objects. Place each imprinted object and the dispersed pink developer prepared in Example 1 on the worktable, marking each object with its development conditions. Hold the object with tweezers, tilt it, and use a pipette to apply the dispersed pink developer evenly onto the fresh blood fingerprint. After the sample dries, rinse with a cleaning agent to remove excess developer and background from the fingerprint lines. Dry the sample with a hairdryer and photograph it for preservation.

[0046] Test Results

[0047] Dispersible pink was dissolved in different solvents at different concentrations, and the results were used to develop blood fingerprints on various objects. The results showed that dispersed pink had better solubility in water, methanol, and mordants than in other solvents. Among the eight solvents prepared at 3% concentrations, the aqueous solution, methanol solution, mordant solution, and aqueous solution of dispersed pink dispersant and mordant showed the best solubility. Solutions in other solvents were essentially saturated when the dispersed pink concentration reached 2%. Dispersible pink dissolved quickly in water, mordants, and dispersant mordants, dissolving in 1-2 minutes, while it took 5-6 minutes to dissolve in other solvents.

[0048] By comparing the development effects of different concentrations and solvents, it can be found that the 3% dispersed pink dispersant mordant solution produces the best development effect on the seven subjects, with continuous and clear blood handprint lines, no or slight staining of the subject background, and high contrast between the lines and the background.

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

[0050] Following the method described in Example 1 for preparing disperse pink developer in various solvents at different concentrations, a series of disperse dye developer solutions with different concentrations of various solvents were prepared. Unlike Example 1, eight different disperse dyes—disperse green, disperse grass green, disperse light yellow, disperse navy blue, disperse lake blue, disperse black, disperse lilac, and disperse scarlet—were selected as dispersion media. Some of the solvents used in Example 1 were selected as experimental solvents, namely methanol, mordant, glacial acetic acid in methanol (glacial acetic acid: methanol = 1:9), and a mixture of dispersant and mordant in hydrated solution (dispersant: mordant = 1:9). A total of 320 disperse dye developer solutions were prepared.

[0051] Example 4: Testing the development effect of disperse dye developers with various solvents at different concentrations

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

[0053] This embodiment uses the optimal formula for disperse pink as a basis, and selects 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 lilac, and disperse scarlet (a total of 8 types), as dispersion media. Methanol, mordant, glacial acetic acid in methanol (glacial acetic acid: methanol = 1:9), and a mixture of dispersant and mordant (dispersant: mordant = 1:9) are selected as solvents for the screening experiment of disperse dyes, with a concentration range of 2% to 4%. The fingerprint development effect of different solvents and concentrations of dyes is compared. The experimental results show that the solubility of the eight selected disperse dyes in the same solvent is not entirely the same, but the development effect is best with a concentration of 3% and a mixed aqueous solution of dispersant and mordant as the solvent. Figure 3 It is a 3% concentration of dispersible navy blue mordant solution that produces the effect of a fresh blood handprint.

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

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

[0056] Through the above experiments, it has been determined that a 3% aqueous solution of disperse dye dispersant mordant is the best developing agent. However, the developing effect of disperse dye is also related to the rinsing operation. If the rinsing is not thorough, the background color may be too dark and cannot be rinsed clean, making it difficult to distinguish from the trace. If the rinsing is not done properly, the bloody handprint may be lightly colored and diffused after development, affecting the effect.

[0057] Choice of rinsing agent

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

[0059] Selection of rinsing method

[0060] In the protein staining assay for developing blood fingerprints, there are two common rinsing methods: one is to rinse first and then dry, and the other is to dry first, then rinse, and finally dry. To screen for the optimal rinsing method, this embodiment uses the aforementioned two rinsing methods and compares their development effects.

[0061] For ease of explanation, the rinsing method is defined as follows:

[0062] Rinsing method a is to rinse first after applying the developer (until the background is cleaned) and then blow dry;

[0063] Rinsing method b involves first drying the solution after applying the developer, then rinsing (until the background is completely removed), and finally drying it again.

[0064] The five rinsing agents and different rinsing processes mentioned above were screened to determine the optimal rinsing agent and method. To reduce the repetition rate of the experiment and simplify the experimental procedure, dispersed pink developer was selected as the developing reagent for this experiment. Following the basic experimental procedure, fresh blood fingerprints on tiles under the same conditions were developed using 3% dispersed pink mordant developer, and different rinsing agents and different rinsing processes were used.

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

[0066] The experimental results show that using a mixture of water and dispersant mordant as a rinsing agent after development, followed by air drying, results in well-developed handprints with good staining, no diffusion, clear lines, and high contrast. Water is also the most environmentally friendly, cheapest, and most readily available rinsing agent. Therefore, water is the best rinsing agent for dispersing pink pigment and developing blood handprints, and the air-drying method after rinsing is the optimal rinsing method.

[0067] Verification Experiment

[0068] Through the above screening experiments, water was determined to be the best rinsing agent for developing blood handprints using disperse pink dyes, and rinsing method a was deemed the optimal method. To verify whether this rinsing agent and method are suitable for rinsing operations after developing other colors of disperse dyes, a verification experiment was conducted on the lower half of the sample.

[0069] Dispersant green, disperse grass green, disperse light yellow, disperse cerulean blue, disperse navy blue, disperse black, disperse lilac, and disperse scarlet were prepared at 3% concentrations (dispersant-mordant ratio 1:9). Following the basic procedure for developing blood handprints, fresh blood handprints on non-porous surfaces such as ceramic tiles were developed one by one. After development, water was used as the rinsing agent, and the surface was rinsed using a rinsing and drying method. After rinsing, photographs were taken to fix and record the development effect.

[0070] The experimental results show that using water as the rinsing agent and then drying after rinsing with disperse dyes is an effective method for developing fresh blood fingerprints on non-permeable surfaces. After rinsing, the fingerprint lines are clear, without fading, adhesion, or diffusion; the contrast is high, and the background is unstained or only slightly stained. Through experimental screening and verification, water has been determined to be the optimal rinsing agent for developing blood fingerprints with disperse dyes, and rinsing followed by drying is the best rinsing method.

[0071] Example 6: Research on methods for revealing permeable objects

[0072] For developing blood fingerprints on impermeable surfaces, previous experiments have identified the optimal solvent, concentration, rinsing agent, and rinsing method for disperse dyes. Disperse dyes do not readily stain impermeable surfaces, allowing for direct development.

[0073] Because disperse dyes readily stain fibers and textiles, the background of bloody handprints on non-porous surfaces such as printing paper, kraft paper, and textiles can easily be stained by the disperse dyes. To prevent this staining, pretreatment is necessary before development.

[0074] To broaden the application of disperse dye development, and to find the optimal method for developing bloody handprints on permeable objects using disperse dyes, it is necessary to conduct experimental screening to determine the best method for developing bloody handprints on permeable objects using disperse dyes.

[0075] Combining conventional bloodstain diffusion prevention methods with the unique physical and chemical properties of disperse dyes, and based on the development characteristics and solvent properties of disperse dye development, the following pretreatment methods were selected through simple preliminary experiments: hydrogen peroxide rinsing, anhydrous ethanol-hydrogen peroxide mixture rinsing (ethanol:hydrogen peroxide = 1:1), hydrogen peroxide immersion, distilled water immersion, mordant immersion, and dispersant-mordant immersion (dispersant:mordant = 1:9). These are respectively denoted as: pretreatment method a, pretreatment method b, pretreatment method c, pretreatment method d, pretreatment method e, and pretreatment method f.

[0076] Screening of preprocessing methods

[0077] The series of disperse dyes share similar physical and chemical properties, and therefore require similar pretreatment methods for developing blood fingerprints on penetrating objects. In the screening experiment for the optimal pretreatment method, Disperse Pink was selected as the developing reagent, and the other eight disperse dyes were used for verification experiments.

[0078] A 3% dispersant pink dispersant mordant (dispersant:mordant = 1:9) and developer were prepared. Before development, fresh blood fingerprints on the permeable objects were treated using six pretreatment methods: a, b, c, d, e, and f. The permeable objects used were: printing paper, kraft paper, unbleached wood, and textiles. Each developed object was marked and photographed.

[0079] The experimental results show that the pretreatment using method f (dispersant mordant immersion method) yields the best development effect. Four types of objects—printing paper, kraft paper, natural wood, and textiles—were immersed in a mixture of dispersant mordant and developer for 1 second, 3 seconds, 5 seconds, 10 seconds, 15 seconds, 30 seconds, and 60 seconds, respectively. Blood fingerprints on the immersed objects were developed one by one using a 3% dispersant pink dispersant mordant developer, and the optimal immersion time was selected by comparing the development results. Among them, the dispersant red developer and dispersant black developer showed the best results in developing blood fingerprints on penetrating objects. Figures 5-6 As shown.

[0080] The experimental results show that before developing bloody handprints with disperse pink dispersant-mordant solution, soaking the subject in a mixture of dispersant and mordant before development results in clear, unblemished, and diffused bloody handprint lines on the penetrating subject. The subject is not stained or only slightly stained, which does not affect the development effect. Other pretreatment methods all damage the handprint lines to varying degrees and stain the subject to varying degrees, affecting the development effect. Finally, soaking the subject in a mixture of dispersant and mordant (dispersant:mordant = 1:9) for 5-10 seconds is determined to be the optimal pretreatment method for developing bloody handprints on penetrating subjects with disperse dyes.

[0081] Verification Experiment

[0082] The above experiments have identified the optimal pretreatment method for displaying blood handprints on penetrating objects with disperse pink dye. To verify whether this method is applicable to other dye series, validation experiments are needed.

[0083] Disperse Green, Disperse Grass Green, Disperse Yellow, Disperse Lake Blue, Disperse Navy Blue, Disperse Black, Disperse Lilac, and Disperse Scarlet were selected as experimental reagents. A series of disperse dye dispersants, mordants (dispersant:mordant = 1:9), and developers were prepared at a concentration of 3%. Using the optimal pretreatment method selected in previous experiments, bloody handprints on printing paper, kraft paper, unbleached wood, and textiles were treated, and then the treated bloody handprints were developed one by one using the series of disperse dye solutions. After development, photos were taken and recorded promptly.

[0084] The experimental results show that the series of disperse dyes, using a pretreatment method of soaking the subject in dispersant mordant, produce good results in displaying bloody handprints on penetrating subjects. Bloody handprints on printing paper, kraft paper, and natural wood show clear lines and minimal background staining.

[0085] Since disperse dyes are mainly used in the chemical industry for dyeing polyester and its blended fabrics, they have a strong dyeing effect on textiles, resulting in rapid and long-lasting staining. Therefore, when developing blood fingerprints on textiles with disperse dye solutions, it is essential to perform anti-staining treatment; otherwise, the textiles will be stained. Textiles soaked in dispersant mordants can be effectively developed using disperse dye developers, resulting in good development, clear lines, and minimal staining.

[0086] Through screening and verification experiments, it was finally determined that immersing the penetrating object in a mixture of dispersant and mordant (dispersant:mordant = 1:9) for 5-10 seconds is the optimal pretreatment method. Using this method, the development of bloody handprints on penetrating objects was successfully achieved, demonstrating excellent results in developing bloody handprints with disperse dyes.

[0087] Example 7: Sensitivity Test of Disperse Dye Developer

[0088] Through a series of experiments, a 3% concentration of dispersed pink dispersant mordant and developer has been determined as the optimal formulation, water as the optimal rinsing agent, air drying after rinsing as the optimal rinsing process, and immersion in a penetrating guest solvent as the pretreatment method. However, to further analyze the practicality of this developer in real-world applications, sensitivity tests were conducted on blood handprints diluted to different concentrations using this method, in order to comprehensively, objectively, and accurately determine the effectiveness of the new development method.

[0089] Dispersible pink developer sensitivity test

[0090] The required original blood fingerprints and several blood fingerprints diluted with water to concentrations of 50%, 20%, 10%, 5%, 2%, and 1% were made on ceramic tiles, glass, plastic sheets, aluminum alloy, PVC boards, printing paper, and natural wood. Following basic development procedures, each fingerprint was developed using a 3% dispersant-mordant-developer mixture. Before developing the blood fingerprints on printing paper and natural wood, the objects were immersed in the dispersant-mordant mixture for 5 seconds to prevent the bloodstains from spreading and to prevent staining. Photos were taken and recorded immediately after development.

[0091] The results show that the 3% disperse pink dispersant mordant developer has good sensitivity and can also show good development effect on blood fingerprints diluted to 5%, especially on smooth, non-porous surfaces such as ceramic tiles, glass, plastic sheets, aluminum alloys, and PVC boards. The developed fingerprints have good staining effect, clear lines, and high contrast. However, when the concentration is below 2%, the development effect on various surfaces is very poor. This is because the staining ability of any dye has a certain limit, and it can only achieve good results within a certain range. When the concentration of blood fingerprints is too low, that is, below 2%, the development effect of disperse pink is very poor.

[0092] Verification Experiment

[0093] The sensitivity of the disperse pink developer has been determined through experiments. A 3% disperse pink mordant developer showed good development of bloody handprints diluted to 5%, producing well-developed handprints with clear lines and high contrast. However, the development effect was poor at concentrations below 2%. This part of the experiment requires testing the development effect of other dye series on bloody handprints diluted to 5% to determine the sensitivity of disperse dyes in developing bloody handprints.

[0094] Several bloody handprints diluted to 5% were pressed onto ceramic tiles, glass, plastic sheets, aluminum alloy, PVC boards, printing paper, and natural wood. Following basic development procedures, each handprint was developed using a series of disperse dyes at a concentration of 3%, along with a dispersant, mordant, and developer. For the bloody handprints on printing paper and natural wood, anti-blood staining and anti-staining treatments were applied before development. Photos were taken and recorded immediately after development.

[0095] The results show that the series of disperse dyes, dispersants, mordants, and developers at a concentration of 3% all have good development effects on blood handprints diluted to a concentration of 5%. The developed handprints have good staining effects, clear lines, high contrast, no diffusion of bloodstains, and no or slight staining of the object.

[0096] Example 8: Study on the time-dependent properties of disperse dye developer

[0097] Examples 1-7 mainly involve experiments on solvent screening, formulation determination, rinsing agent and rinsing method research, and permeable object development method research. The bloody handprints developed in these experiments are all fresh bloody handprints, while bloody handprints left at crime scenes are often not fresh. In order to test the development effect of disperse dye developers on old bloody handprints, it is necessary to conduct time-dependent studies on disperse dye developers.

[0098] Old blood handprint making

[0099] Several bloody handprints were made at different times on ceramic tiles, glass, plastic sheets, aluminum alloy, PVC boards, artificial leather, kraft paper, printing paper, and natural wood, respectively, at intervals of 6 months, 3 months, 2 months, 1 month, 20 days, 10 days, 5 days, 3 days, 2 days, and 1 day after the demonstration experiment. The bloody handprints were stored in a cool, dry place.

[0100] Experimental Operation

[0101] Several bloody handprints were selected from various objects at different times: 1 day, 2 days, 3 days, 5 days, 10 days, 20 days, 1 month, 2 months, 3 months, 6 months, and freshly made. These were then developed sequentially using a 3% concentration of dispersed pink dispersant mordant and developer, following the basic operating procedure.

[0102] The experimental results show that the development effect of 3% disperse pink dispersant mordant developer is not greatly affected by the time the blood fingerprint has been left. It can also have a good effect on blood fingerprints left for 6 months. This is because proteins have strong stability under normal conditions. As long as the blood fingerprint does not decompose, even if the time left is relatively long, it can be successfully developed by simply extending the development time or repeating the development several times to allow the reagent to penetrate the bloodstain.

[0103] Verification Experiment

[0104] A 3% concentration of disperse pink dispersant mordant developer showed excellent results on old blood fingerprints that had remained for 6 months. To verify the development effect of a series of disperse dyes on old blood fingerprints and to determine the time-limited effectiveness of the disperse dye developer, validation experiments were conducted.

[0105] Several old bloody handprints from various objects that have been exposed for 6 months were selected and developed sequentially using 3% concentrations of disperse green, disperse grass green, disperse light yellow, disperse lake blue, disperse navy blue, disperse black, disperse lilac, and disperse scarlet as mordants and developers. Pretreatment is required before developing penetrating objects.

[0106] Experiments verifying the time-limited properties of a series of disperse dyes revealed that they all exhibit a wide range of time-limited effects, demonstrating excellent visibility even on bloody handprints left for up to 6 months. Disperse dyes can reveal bloody handprints ranging from fresh to old. Specifically, a 3% concentration of disperse lilac mordant solution showed particularly good visibility on old bloody handprints. Figure 4 As shown.

[0107] Example 9: Stability test of the developer

[0108] Because disperse dyes have low solubility, disperse dye developers may precipitate after prolonged storage, thus affecting the development effect. To determine the stability of the development reagent and the optimal storage method, a stability experiment was conducted on a 3% concentration of disperse pink dispersant mordant developer.

[0109] Experimental Operation

[0110] Prepare 8 portions (10 ml each) of 3% dispersible pink mordant and developer every 1 to 10 days. Store in a sealed container in a cool, dry place at room temperature. Following the basic procedure for developing blood handprints, develop blood handprints on different subjects using freshly prepared 3% dispersible pink mordant and developer solutions, as well as solutions stored for 1, 2, 3, 5, 10, 15, 20, and 30 days.

[0111] The experimental results show that 3% of the dispersible pink dispersant, mordant, and developer can be stored for a long time under sealed conditions without deterioration or affecting the development effect. This is mainly because the solution is stable, and neither the dispersant nor the mordant reacts with air components. It is not greatly affected by temperature and humidity, so it 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. To verify the stability of the series of dyes, a series of dye stability verification experiments were conducted.

[0114] Following the basic preparation method of disperse dye developers, a series of disperse dyes, mordants, and developers with a concentration of 3% were prepared at different time intervals. These were stored in a cool, dry place at room temperature. Fresh blood fingerprints on various objects were developed sequentially using the series of dye developers stored for 30 days. Before developing penetrating objects, treatments were performed to prevent bloodstain diffusion and staining. Photos were taken and recorded promptly after development; the results are shown in Table 2.

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

[0116] Table 2. Development effects of a series of dye developers stored for 30 days on fresh blood fingerprints on different subjects.

[0117]

[0118]

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

[0120] Example 10: Complementary Color Study of a Series of Disperse Dye Developers

[0121] complementary color principle

[0122] Disperse dyes are diverse and offer a complete color spectrum. When revealing bloody handprints, the appropriate dye can be selected based on the color of the object. Because disperse dyes have relatively vibrant colors, light-colored objects are not limited by the color of the disperse dye. For dark-colored objects, it is necessary to choose an appropriate color to reduce the contrast between the handprint and the background. The principle of complementary colors should be followed when selecting colors.

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

[0124] (1) Complementary colors in color

[0125] Mixing complementary colors will reduce their purity, turning them into gray. Generally, complementary colors are not used in painting. However, when two colors are complementary, and one color occupies a much larger area than the other, it can enhance the contrast of the image, making it more eye-catching. Generally, the use of complementary colors has both advantages and disadvantages.

[0126] (2) Complementary colors in optics

[0127] If two colors of light (monochromatic or polychromatic) mixed in appropriate proportions produce the sensation of white, then these two colors are called "complementary colors." 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—that is, any one of the three primary colors—is complementary to the mixture of the other two. Subtracting complementary colors (such as applying two complementary colors to the same spot on white paper when mixing pigments) results in black. When complementary colors are placed side by side, they create a strong contrast in color perception, making red appear redder and green appear greener. Reducing the saturation of complementary colors tends to create a more harmonious effect. The color of a non-luminous object (such as pigment) depends primarily on its absorption and reflection of external light, so the color of the object is related to the light it receives. Generally, the color of an object under daylight is called the color of that object. When daylight shines on a surface formed by mixing yellow and blue, the yellow pigment reflects all four colors of white light—red, orange, yellow, and green—while the blue light absorbs the red, orange, and yellow colors, resulting in a green color in the mixture. This color mixing differs from additive color mixing and is called subtractive color mixing. An object that completely reflects white light is called a white body; an object that completely absorbs incident light is called a black body (absolute black body).

[0128] Complementary color experiment

[0129] Several color swatches of red, yellow, green, and blue were selected. Blood handprints were pressed onto the color swatches, and then developed one by one using a series of disperse dyes, dispersants, mordants, and developers with a concentration of 3% prepared in Examples 1 and 3. The results were photographed and recorded.

[0130] As can be seen from the above development results, disperse dyes develop vibrant colors in the bloody handprint lines, with a high contrast to the background color and minimal influence from the background color. However, for bloody handprints on a color chart of the same color as the dye, the developed lines are similar in color to the background, with low contrast, making observation and photographic extraction difficult. Therefore, when selecting disperse dyes to develop bloody handprints, dyes with colors similar to the background color should be avoided. Figures 1-2 The images shown are the effects of developing blood handprints on color plates using dispersed pink developer and dispersed green developer, respectively.

[0131] Comparative Example 1: Comparison of the development method of the present invention with conventional development methods

[0132] Comparison of bloody handprints on non-permeable objects

[0133] This experiment uses the disperse dye development method to compare 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 common technical formulations.

[0134] The experimental procedure is as follows: 1) Disperse dye development method and Coomassie Brilliant Blue developer were used to develop blood fingerprints left on different objects. The upper half of the fingerprint was developed using disperse dye, and the lower half using Coomassie Brilliant Blue. 2) Disperse dye development method and Amine Black 10B developer were used to develop blood fingerprints on different non-permeable objects. The upper half of the fingerprint was developed using disperse dye, and the lower half using Amine Black 10B. The fingerprint development effects were compared and recorded.

[0135] like Figure 7 The image shows a comparison of the effects of disperse dye developer (top) and Coomassie Brilliant Blue developer (bottom) on developing bloody handprints. The experimental results show that disperse dye developer can effectively develop bloody handprints on non-porous surfaces; Coomassie Brilliant Blue can also develop bloody handprints on various non-porous surfaces. However, the solvent for Coomassie Brilliant Blue developer is a mixture of ethanol and glacial acetic acid. Ethanol is volatile, and glacial acetic acid has a pungent odor. The solvent for disperse dyes, on the other hand, is non-toxic, harmless, and odorless. In terms of environmental friendliness, disperse dye developer is superior to Coomassie Brilliant Blue developer.

[0136] Compared to the amino black 10B developing method, disperse dyes show good development results for bloody handprints on light-colored objects. However, for bloody handprints on dark-colored objects, the contrast between the handprint lines and the background color is small after developing with amino black 10B, resulting in poor development. Therefore, the development of bloody handprints with amino black 10B is greatly affected by the background color of the object and is not suitable for developing bloody handprints on dark-colored objects. In contrast, the disperse dye developing method offers a range of different shades of color, making it suitable for developing handprints on both light-colored and dark-colored objects, thus demonstrating superior applicability compared to the amino black 10B developing method.

[0137] A comparison of the appearance of bloody handprints on permeable objects

[0138] There are many methods for developing blood fingerprints on permeable surfaces such as white paper, silk, kraft paper, and natural wood. Commonly used methods include the tetramethylbiphenyl (TMB) development method and the dimethylformaldehyde (DFO) development method. This experiment mainly uses these two methods for comparative study with the disperse dye development method. Both the TMB and DFO development methods use common formulations.

[0139] The experimental procedure is as follows: bloody handprints on different objects were developed using disperse dye developer and TMB developer. The upper half of the object was developed using disperse dye developer, and the lower half of the object was developed using TMB developer. Bloody handprints on different objects were also developed using disperse dye developer and DFO developer. The upper half of the object was developed using disperse dye developer, and the lower half of the object was developed using DFO developer.

[0140] The development results show that, for bloody handprints on porous surfaces, both the disperse dye method and the TMB method produce good development results, with clear lines and minimal background staining. However, for bloody handprints on dark-colored surfaces, the TMB method results in less contrast between the background and the lines, making observation difficult.

[0141] like Figure 8 The image shows a comparison of the effects of disperse dye developer (top) and DFO (bottom) on developing bloody handprints. Compared to the DFO development method, the disperse dye development method produces better results, and the DFO development method is more complex and time-consuming.

[0142] In summary, based on the physicochemical properties of disperse dyes and utilizing their dyeing principles, this study analyzes their characteristics and the influencing factors of solution concentration, solubility, and reaction during the preparation process. Through a series of rigorous scientific experiments, the following conclusions are drawn:

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

[0144] (2) Water is the best rinsing agent for the appearance of bloody handprints by disperse dyes. Rinsing first and then drying is the best rinsing method.

[0145] (3) Soak the penetrating object in a mixed aqueous solution of dispersant and mordant (dispersant:mordant = 1:9) for 5 to 10 seconds. This method was used as a pretreatment for the development of blood fingerprints on penetrating objects, achieving good development results for blood fingerprints on penetrating objects using disperse dyes.

[0146] (4) Disperse dyes have a good display effect on bloody handprints diluted 20 times and old bloody handprints left for 6 months.

[0147] (5) Disperse dye developers have excellent stability and can be stored for a long time under sealed conditions without deterioration, precipitation, or affecting the development effect.

[0148] As can be seen from the above, disperse dye developers are a new type of developer that is non-toxic, harmless, easy to prepare, and convenient to store; the disperse dye development method is simple to operate and easy to rinse, and can develop fresh and old blood handprints and bloodstains on penetrating, semi-penetrating and non-penetrating objects.

[0149] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for revealing bloodstains, characterized in that, Includes the following steps: S1. Immerse the permeable object with bloodstains in an aqueous solution of dispersant and mordant for 5-10 seconds; S2. After soaking, tilt the permeable object, apply the bloodstain developing agent evenly to the bloodstain, keep it for 1-2 minutes, rinse the object with water, and then blow it dry. The bloodstain developing agent comprises a disperse dye and a solvent; The concentration of the disperse dye is 2% to 4%, and the solvent is a mixed aqueous solution of dispersant and mordant; The concentration of the dispersant-mordant mixed aqueous solution is 3%, and the mass ratio of dispersant to mordant is 1:9; The mordant is Pingpingjia O; 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 lilac and disperse scarlet.

2. The bloodstain revealing method according to claim 1, characterized in that, The dispersant is BX (a type of dispersant).

3. The bloodstain revealing method according to claim 1, characterized in that, The permeable objects include printing paper, kraft paper, natural wood, and textiles.

Images