Water-based reagent capable of rapidly spraying fingerprints

Abstract

The invention provides a water-based reagent capable of rapidly spraying fingerprints, and belongs to the technical field of fingerprint detection. The fingerprint rapid development reagent is composed of organic carboxylic acid with a plane inner symmetric structure, a buffer reagent with the pH higher than that of a protein isoelectric point, and a mixed solution of europium ions and aluminum ions. The use method comprises the following steps: spraying the mixed solution on the surface of a latent fingerprint object, wherein bright red fingerprint lines can be observed under an ultraviolet lamp. The method does not need to prepare a rare earth ion coordination polymer or solid powder particulate matter in advance, is good in water solubility, is not limited by a to-be-displayed object during use, and is rapid in fingerprint display, high in reagent fluorescence efficiency and small in dosage. After fingerprints are shown by the reagent, evidences in the aspect of DNA result judgment are not affected by shown objects, and the reagent can be used as a guiding reagent for DNA sampling.

Description

Technical Field

[0001] The invention relates to the technical field of fingerprint detection, and in particular to an aqueous reagent for rapidly spraying fingerprints. Background Art

[0002] Fingerprints are different for each person, remain unchanged throughout life, and leave traces on objects. Fingerprint identification is one of the most reliable methods of personal identification. Scientifically and correctly discovering, extracting, and identifying fingerprints plays an important practical role in conducting investigative work and punishing crimes.

[0003] The methods currently used for on-site fingerprint visualization are mainly: optical visualization, physical visualization and chemical visualization. These methods have the following two main problems: (1) The visualization reagents used are harmful to the health of on-site investigators. Powder (single powder, synthetic powder, magnetic powder and fluorescent powder, etc.) visualization reagents, volatile reagents and solvents are easily inhaled; fluorescent powders are highly toxic and carcinogenic, which makes technicians afraid to use them. (2) It requires the use of many accessories and operations, such as hot ironing, steam, brushing, fumigation, etc., which makes technicians unwilling to use them. For example, patent application number 202310921979.5 on the use of trichloro-di-(1,10)-phenanthroline europium complex in latent fingerprint visualization requires a complex process to prepare fluorescent powder for brushing, which cannot be applied on vertical, horizontal, wet or uneven surfaces. Application No. 202311048186.3, Application of 1,10-phenanthroline-tri[4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione]europium in latent fingerprint development and Application No. 202110766049.8, A method for preparing an orange-red phosphor and its application patent in latent fingerprint extraction, adopt the traditional brush development method, which treats the object to be developed similarly to immersion. The reagent has low fluorescence efficiency and large dosage. It is only effective for non-permeable objects (such as glass, etc.), and the cost and technical requirements when used are very high.

[0004] The display effect on common permeable objects is of great significance, but the existing technology has little obvious display effect on permeable objects.

[0005] Therefore, on-site investigators have an urgent need for new technologies, methods and products for fingerprint display that are efficient, convenient, green and safe. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide an aqueous reagent for rapid latent fingerprint visualization.

[0007] Another object of the present invention is to provide a method for preparing the aqueous reagent for rapid fingerprint spraying and its application.

[0008] The object of the present invention is achieved in the following ways:

[0009] A water-based reagent for rapid fingerprint spraying, the reagent is composed of an organic carboxylic acid with a symmetrical structure, a pH buffer solution, a europium ion solution and an aluminum ion solution. The molar ratio of the organic carboxylic acid to the europium ion is (0.5-5):1, preferably 1:1; the molar ratio of the organic carboxylic acid to the aluminum ion is (1-10):1, preferably 2:1.

[0010] The organic carboxylic acid has a symmetrical structure, preferably one of phthalic acid, trimesic acid or pyromellitic acid. The symmetric structure of the molecule (rollover symmetry, axisymmetry, rotational symmetry) can further facilitate the formation of larger molecules extending in all directions of the plane with europium, thereby enhancing the fluorescence effect.

[0011] The organic carboxylic acid solution is an organic carboxylic acid aqueous solution with a concentration of 1.0×10 -3 mol·L -1 ~20×10 - 3 mol·L -1 The preferred concentration is 2.0×10 -3 mol·L -1 The concentration of the europium ion solution is 1.0×10 -3 mol·L -1 ~10×10 -3 mol·L -1 The preferred concentration is 2.0×10 -3 mol·L -1 The concentration of the aluminum ion solution is 1.0×10 - 3 mol·L -1 ~10×10 -3 mol·L -1 The preferred concentration is 1.0×10 -3 mol·L -1 Preferably, the europium ion solution is an aqueous europium sulfate solution, and the aluminum ion solution is an aqueous aluminum sulfate solution.

[0012] The pH of the pH buffer solution of the present invention should be higher than the isoelectric point of the protein. The preferred buffer solution is a Tris buffer solution or a borax-hydrochloric acid buffer solution, and the pH of the buffer solution is more preferably 8-9.

[0013] The method for preparing the aqueous reagent for rapid fingerprint spraying is to mix an organic carboxylic acid, a pH buffer solution, a europium ion solution and an aluminum ion solution.

[0014] The aqueous reagent for rapid fingerprint spraying of the present invention can be used in fingerprint detection. The specific steps are: spraying the aqueous mixture on the surface of the latent fingerprint object, and observing bright red fingerprint lines under ultraviolet light. The wavelength of the ultraviolet light is 254nm. The latent fingerprint object is metal, glass, plastic, ceramic, leather, log, organic glass or paint surface.

[0015] Protein is an important substance constituting fingerprint lines. The present invention uses a buffer solution to make the pH of the medium higher than the isoelectric point of the protein, so that the protein molecules carry a negative charge, which is conducive to their combination with europium ions. The europium ions then combine with organic carboxylic acids with a symmetrical structure to form macromolecules with a spatially extended structure and fluorescent properties. Aluminum ions fill the vacancies left by europium ions, thereby reducing the reagent cost without reducing the fluorescence intensity.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] (1) All reagents used are water-soluble and are colorless, odorless, water-based, green and safe.

[0018] (2) There is no need to prepare rare earth ion coordination polymers or solid powder particles in advance, and fingerprints appear quickly.

[0019] (3) The liquid solution of the present application can be well adapted to different object surfaces such as metal, glass, plastic, ceramic, leather, log, plexiglass, paint, etc., and can be applied on vertical surfaces, upward surfaces, wet surfaces, and uneven surfaces without being restricted by the surface. In particular, it has a good display effect on permeable objects (paper, leather, log, etc.), and can minimize the impact of fingerprint display on the object to be displayed.

[0020] (4) The present application adopts a spray display method, the reagent has high fluorescence efficiency and small dosage.

[0021] (5) After preparation, it can be stored stably at room temperature for a long time and can be used directly.

[0022] (6) Trivalent aluminum ions have no fluorescent effect. The present invention uses cheap trivalent aluminum ions without affecting the formation of luminescent macromolecules with spatial extensibility, thereby reducing costs while maintaining a high luminescence efficiency.

[0023] (7) After the fingerprint is revealed by the reagent, the revealed object does not affect the evidence of the determination of the DNA result. The reagent of the present invention can be used as a guiding reagent for DNA sampling. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the effect of showing fingerprints on the surface of A4 paper in Example 1;

[0025] Figure 2This is the effect of showing fingerprints on the surface of latex gloves in Example 2;

[0026] Figure 3 This is the effect of fingerprints appearing on the surface of the Chlorophytum leaf in Example 3.

[0027] Figure 4 This is the effect of fingerprint display on the desktop of Example 1.

[0028] Figure 5 This is the effect of fingerprints appearing on the wall of Example 2. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and drawings. This embodiment is implemented on the premise of the technical solution of the invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0030] Example 1

[0031] 1 mL of phthalic acid aqueous solution (2.0×10 -3 mol·L -1 ), 1 mL Tris aqueous solution (1.5×10 - 3 mol·L -1 ), 1 mL europium sulfate solution (2.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (1.0 × 10 -3 mol·L -1 ) and mix well for later use. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under the irradiation of 254nm ultraviolet light, the fingerprint lines emit red fluorescence (see Figure 1 ).

[0032] Example 2

[0033] 1 mL of trimesic acid aqueous solution (2.0×10 -3 mol·L -1 )、1mL Tris aqueous solution (1.5×10 - 3 mol·L -1 ), 1 mL of europium sulfate aqueous solution (2.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (1.0 × 10 -3 mol·L -1 ) and mix well for later use. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under the irradiation of 254nm ultraviolet light, the fingerprint lines emit red fluorescence (see Figure 2 ).

[0034] Example 3

[0035] Take 1 mL of pyromellitic acid aqueous solution (2.0×10 -3 mol·L -1 ), 1 mL borax-hydrochloric acid buffer solution (1.0×10 -2 mol·L -1 ) (pH 8-9), 1 mL of europium sulfate aqueous solution (2.0 × 10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (1.0 × 10 -3 mol·L -1 ) and mix well for later use. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under the irradiation of 254nm ultraviolet light, the fingerprint lines emit red fluorescence (see Figure 3 ).

[0036] Comparative Example 1

[0037] 1 mL of phthalic acid aqueous solution (2.0×10 -3 mol·L-1), 1mL Tris aqueous solution (1.5×10 - 3 mol·L-1), 1mL europium sulfate solution (1.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (2.0 × 10 -3 mol·L -1 ) Mix well and set aside. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under the irradiation of 254nm ultraviolet light, the fingerprint lines are not clearly fluorescent (see Figure 4 ).

[0038] Comparative Example 2

[0039] 1 mL of benzoic acid aqueous solution (2.0×10 -3 mol·L -1 ), 1 mL Tris aqueous solution (1.5×10 -3 mol·L -1 ), 1 mL of europium sulfate aqueous solution (2.0×10 -3 mol·L -1 ) and 1 mL of aluminum sulfate aqueous solution (1.0 × 10 -3 mol·L -1 ) Mix well and set aside. Use a spray bottle to spray the mixed solution onto the surface of the latent fingerprint object. Under the irradiation of 254nm ultraviolet light, the fingerprint lines are not clearly fluorescent (see Figure 5 ).

[0040] Experimental Example 1: Investigating the Effect of Using the Aqueous Reagent in Example 1 to Visualize Fingerprints on DNA Testing

[0041] The appearance of sweat latent fingerprints and the subsequent DNA detection of exfoliated cells attached thereto are important contents of forensic science research in recent years. The sweat latent fingerprints after appearance by the verification reagent of the present invention will not affect the subsequent DNA test.

[0042] 1. Fingerprint sample preparation method

[0043] This experiment chose to make samples in the laboratory, with a temperature of 32°C and a relative humidity of 75%. In order to eliminate other influences, the samples prepared in the experiment were formed in one go and tested on two slides, that is, two slides were connected and the fingerprint was pressed on the seam of the two slides, so that half of the fingerprint was formed on each of the two slides.

[0044] 2. Experimental Design

[0045] The two glass slides carrying fingerprints are separated, half of the fingerprint on one of the glass slides is sprayed with the reagent of the present invention and then subjected to DNA testing; the other glass slide not sprayed with the reagent of the present invention is directly subjected to DNA testing, and the two test results are compared.

[0046] 3. Sample preparation

[0047] In order to eliminate the possibility of chance, the experiment selected two volunteers, A and B, to provide samples. Each person provided samples 30 times. The method of one-time forming and double slide inspection was adopted. The fingerprint was pressed on the joint of the two slides, and the fingerprint formed at one time was half on each of the two slides.

[0048] The slides were separated according to whether they were sprayed with reagents or not. The original fingerprint samples provided by volunteer A were recorded as A1-A30, and the samples after spraying with reagents were recorded as a1-a30 accordingly. The original fingerprint samples provided by volunteer B were recorded as B1-B30, and the samples after spraying with reagents were recorded as b1-b30 accordingly. There were a total of 120 samples.

[0049] 4. Inspection methods

[0050] This experiment was tested and analyzed in accordance with the industry standards GA / T 383-2014 and GA / T 1163-2014. The exfoliated cells at the fingerprint pressing site on the slide were carefully transferred to a 1.5mL centrifuge tube using a two-step wet and dry wiping method with a cotton swab, and DNA was extracted and purified using the silica bead method, with the operation steps optimized. The above DNA extraction product was purified using AmpFlSTR Plus was used to perform compound amplification of 16 loci on a 9700 thermal cycler. The system was 15 μL, of which 6 μL was DNA template, and the reaction was performed for 30 cycles. 1 μL of amplified product was mixed with 0.5 μL internal standard LIZ500 and 9.5 μL deionized formamide, and the mixture was placed on a 3500XL genetic analyzer for fully automatic capillary electrophoresis. The data were collected using the Collection software. Allele typing was performed using ID-X software.

[0051] 5. Test results:

[0052] Table 1 Comparison table of fingerprint samples of volunteer A and DNA data before and after spraying reagent

[0053]

[0054]

[0055] Table 2 Comparison of DNA data of volunteer B's fingerprint samples before and after spraying the reagent

[0056]

[0057]

[0058] 6. Experimental analysis:

[0059] All 30 pairs of samples of volunteer A were detected. The highest peak value of the fingerprint sample before spraying the reagent was 10000, the lowest peak value was 1000, and the average peak value was 3730; the highest peak value of the fingerprint sample after spraying the reagent was 15000, the lowest peak value was 1000, and the average peak value was 3516. Both sets of data before and after spraying the reagent were all detected and the average peak values ​​were close, indicating that spraying the reagent of the present invention on the fingerprint does not affect the DNA test.

[0060] A total of 27 pairs of 30 pairs of samples from volunteer B were detected, with a detection rate of 90%. The highest peak value of the fingerprint sample before spraying the reagent was 20,000, the lowest peak value was 800, and the average peak value was 2773; the highest peak value of the fingerprint sample after spraying the reagent was 20,000, the lowest peak value was 1000, and the average peak value was 2783. Both sets of data were fully detected and the average peak values ​​were close. After statistical testing, no significant difference was found P>0.05. This shows that spraying the reagent of the present invention on the fingerprint does not affect the DNA test.

[0061] The data numbers of volunteer B that were not detected are B7, b7, B15, b15, B16, and b16, which happen to be the three fingerprints that were not detected before and after spraying the reagent. This means that the fingerprint samples in which DNA was not detected after spraying the reagent could not be detected before spraying.

[0062] 7. Experimental conclusion:

[0063] From the DNA test data of the above 60 pairs of 120 samples, it can be seen that DNA data can be detected before spraying the reagent, and DNA data can still be detected after spraying the reagent; the samples for which DNA was not detected after spraying the reagent were also not detected before spraying.

[0064] Therefore, the sweat latent fingerprints revealed by the reagent of the present invention will not affect the subsequent DNA test.

Claims

1. A water-based reagent for rapid fingerprint spraying, characterized in that The reagent consists of an organic carboxylic acid aqueous solution with a symmetrical structure, a pH buffer solution, a europium ion aqueous solution and an aluminum ion aqueous solution; wherein the molar ratio of the organic carboxylic acid to the europium ion is (0.5-5):1; and the molar ratio of the organic carboxylic acid to the aluminum ion is (1-10):

1.

2. The aqueous reagent according to claim 1, characterized in that The molar ratio of the organic carboxylic acid to the europium ion is 1:1; the molar ratio of the organic carboxylic acid to the aluminum ion is 2:

1.

3. The aqueous reagent according to claim 1, characterized in that The organic carboxylic acid has a symmetrical structure.

4. The aqueous reagent according to claim 3, characterized in that The organic carboxylic acid is one of phthalic acid, trimesic acid or pyromellitic acid.

5. The aqueous reagent according to claim 1, characterized in that The pH of the pH buffer solution is higher than the isoelectric point of the protein.

6. The aqueous reagent according to claim 5, characterized in that The pH buffer solution is one of a Tris buffer solution and a borax-hydrochloric acid buffer solution.

7. The aqueous reagent according to claim 1, characterized in that In the fingerprint rapid development reagent, the concentration of the organic carboxylic acid aqueous solution is 1.0×10 -3 mol·L -1 ~20×10 -3 mol·L -1 The concentration of the europium ion aqueous solution is 1.0×10 -3 mol·L -1 ~10×10 -3 mol·L -1 The concentration of the aluminum ion aqueous solution is 1.0×10 -3 mol·L -1 ~10×10 -3 mol·L -1 .

8. The aqueous reagent according to claim 1, characterized in that The europium ion aqueous solution is a europium sulfate aqueous solution, and the aluminum ion aqueous solution is an aluminum sulfate aqueous solution.

9. A method for preparing an aqueous reagent for rapid fingerprint spraying according to claim 1, characterized in that The organic carboxylic acid aqueous solution, the pH buffer solution, the europium ion aqueous solution and the aluminum ion aqueous solution are mixed to obtain the solution.

10. Use of the aqueous reagent for rapid fingerprint spraying according to claim 1 in fingerprint detection.

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