CN113030073B - Method for extracting, showing and verifying copper and lead residues in bullet traces - Google Patents
Method for extracting, showing and verifying copper and lead residues in bullet traces Download PDFInfo
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Abstract
The invention provides a method for extracting, showing and verifying copper and lead residues in an impact trace. The method comprises the steps of sequentially extracting copper and lead residues in the bullet traces by selecting a specific pretreatment solution and a transfer medium, and respectively developing and verifying the copper and lead extracted by transfer printing by adopting two-step color development treatment. The method can rapidly and reliably obtain qualitative results, distribution positions and distribution morphological characteristics of copper and lead residues in the bullet traces on site, and provides scientific basis and court evidence for rapidly determining whether the bullet traces are bullet traces, analyzing bullet types and judging shooting distances on site.
Description
Technical Field
The invention belongs to the technical field of criminal science, and relates to a method for extracting, showing and verifying copper and lead residues in an impact trace.
Background
The bullet trace refers to a trace formed on an object to be shot by a gun after a bullet is shot by the gun, wherein the bullet head moving at a high speed flies away from a muzzle and shoots towards the target, and the trace comprises a bullet hole, a bullet trajectory, a trace of a bullet point, gunpowder air mass, ash, residues and the like deposited on the surface or the periphery of the object to be shot. Among them, metal residues are important accompaniments in the bullet marks. Sources of metal residues include: metal debris generated when the bullet moves at high speed in the bore and violently rubs with the inner wall of the gun barrel; and when the warhead and the shot object collide with each other and rub violently, metal substances are left on the shot object. The metal residues can reflect the shape and composition characteristics of the shot marks, so that the shot marks can be determined, the shot species can be deduced, the shooting direction and distance can be shot, and the like can be deduced by checking the composition and distribution characteristics of the shot marks, thereby serving the reconstruction of field trajectories.
Pure lead warheads and armor warheads are the two most common warheads, and copper and lead residues in the remaining bullet traces and the distribution state of the copper and lead residues become main detection objects for deducing the bullet traces and deducing the types, the shooting directions and the distances of bullets. For the metal residues, a large-scale analytical instrument such as an atomic emission spectrum instrument, a scanning electron microscope spectrometer and the like is generally adopted for carrying out composition inspection. However, the method can only be used for detection in a laboratory and has low detection speed, so that the field investigation and reconstruction work is delayed, and the bullet traces need to be extracted in situ for detection, so that the original distribution state of metal residues in the bullet traces is damaged, the full utilization of the field bullet trace information is influenced, and the application value of the method in the aspects of analyzing and judging the shooting direction, the shooting distance and the like is reduced.
The rapid inspection of the on-site material evidence by adopting a chemical display method is a common means for criminal case investigation, and has the advantages of simple and convenient operation, high reaction speed, visual result reflection and the like. In the prior art, a method for showing copper and lead residues in the bullet traces independently exists. However, since the types of warheads with left-behind impact traces cannot be predicted in case investigation, copper and lead residues need to be detected simultaneously in the same impact trace, but the existing visualization methods affect each other, so that the determination of the extraction order and visualization order of the copper and lead residues becomes an urgent problem to be solved; in addition, the operator can interfere the judgment of the color development result on the color cognition difference and colored substances generated by the reaction of other environmental metals except copper and lead and the selected color developing agent, so that false negative, false positive and other false judgment results can be generated, and the reliability of the visualization method and the result can be obviously improved if a verification program is added.
In conclusion, the method for quickly extracting, showing and verifying the metal residues in the bullet traces has important significance.
Disclosure of Invention
The invention aims to overcome the technical problem that the species of metal residues and the distribution thereof in the bullet traces left by the pure lead bullets and armor bullets cannot be identified rapidly and reliably in the field in the prior art.
The first technical problem to be solved by the invention is to establish the technical problem of sequential extraction and display of copper and lead residues in the bullet traces.
The second technical problem to be solved by the invention is to improve the method for showing copper and lead residues in the bullet traces and the reliability of the result.
In order to solve the technical problems, the invention provides a method for extracting, showing and verifying copper and lead residues in an impact trace, which comprises the following steps:
1) After the first transfer medium pretreated by the alkaline solution is used for carrying out first sampling on the bullet traces, a first pre-developing reagent is used for carrying out first developing treatment on the first transfer medium;
2) If the first color development result accords with the first preset result, primarily determining that the bullet marks contain copper, and executing the step 3); or if the first color development result does not accord with the first preset result, determining that the bullet trace contains no copper, and executing the step 5);
3) After second sampling is carried out on the bullet traces by using the second transfer medium pretreated by the alkaline solution, second color development treatment is carried out on the second transfer medium by using a first verification reagent;
4) If the second color development result accords with a second preset result, determining that the bullet-sticking trace contains copper; or if the second color development result does not accord with the second preset result, determining that the impact trace contains no copper;
5) After third sampling is carried out on the impact traces by utilizing a third transfer medium pretreated by an acid solution, third color development treatment is carried out on the third transfer medium by adopting a second pre-developing reagent;
6) If the third color development result accords with a third preset result, primarily determining that the bullet-sticking trace contains lead, and executing the step 7); or if the third color development result does not meet the third preset result, determining that the bullet traces contain no lead;
7) Performing fourth color development treatment on the third transfer medium by using a second verification reagent;
8) If the fourth color development result accords with a fourth preset result, determining that the bullet traces contain lead; or if the fourth color development result does not meet the fourth preset result, determining that the bullet traces contain no lead;
wherein the first pre-developing reagent is selected from a rhodomine solution, the first validation reagent is selected from a 2-nitro-1-naphthol solution, the second pre-developing reagent is selected from a sodium rose bengal solution, and the second validation reagent is selected from a hydrochloric acid solution.
Further, the first transfer medium, the second transfer medium, and the third transfer medium as described above are the same and are selected from one of white cardboard, filter paper, coated paper, and printing paper.
Further, the first sampling as described above includes: soaking the first transfer medium in an alkaline solution for 10-300s to obtain a uniformly soaked first transfer medium, closely attaching the uniformly soaked first transfer medium to the impact trace, and pressing for 10-300s; and/or, the second sampling comprises: soaking the second transfer medium in an alkaline solution for 10-300s to obtain a second transfer medium with uniform soaking; tightly attaching the second transfer printing medium which is uniformly soaked with the impact trace, and pressing for 10-300s; and/or, the third sampling comprises: and soaking the third transfer medium in an acid solution for 10-300s to obtain a uniformly soaked third transfer medium, tightly attaching the uniformly soaked third transfer medium to the impact trace, and pressing for 10-300s.
Further, the first color rendering process as described above includes: spraying or dripping 0.1-1.0mL of a first pre-developing reagent to the first transfer medium; and/or the second color development treatment comprises the following steps: spraying or dripping 0.1-1.0mL of first verification reagent on the second transfer medium; and/or, the third color development treatment comprises: spraying or dripping 0.1-1.0mL of second pre-developing reagent to the third transfer medium; and/or the fourth color development treatment comprises: and spraying or dripping 0.1-1.0mL of second validation reagent to the third transfer medium.
Further, the first preset result as described above is a greenish black color; and/or, the second predetermined result as described above is pink; and/or, the third predetermined result as described above is rosy; and/or, the fourth predetermined result as described above is bluish purple.
Further, the alkaline solution is an ammonia solution with the volume concentration of 10-40%; and/or the acid solution is an acetic acid solution with the volume concentration of 10-40%.
Further, the solution of the tryptophan is ethanol or methanol solution of 0.1-0.5% by mass.
Further, the 2-nitro-1-naphthol solution as described above is a 2-nitro-1-naphthol ethanol or methanol solution having a mass concentration of 0.1 to 0.5%.
Further, the sodium rose bengal solution is 0.1-0.5% by mass of sodium rose bengal solution.
Further, the hydrochloric acid solution as described above has a volume concentration of 1.0 to 10.0%.
Compared with the prior art, the invention at least has the following beneficial effects:
1) The method for sequentially extracting and displaying the metal residues in the shot marks is established, the deep excavation of the component information of the metal residues in the same shot marks is realized, and the technical problem that the prior art cannot simultaneously extract and display a plurality of metal residues is solved.
2) The method for showing and verifying the metal residues in the bullet traces is established, the possibility of false negative and false positive results caused by the cognitive difference of the color of an operator, the interference of the color reaction of ions and the like is effectively reduced, and the reliability of the original technology and the results thereof is obviously improved.
3) The method can quickly and reliably identify the impact traces and the distribution thereof without large-scale instrument analysis, has high display speed, easy identification and low cost, and has good popularization prospect.
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Fig. 1 is a flowchart of a method for extracting, visualizing and verifying copper and lead residues in an impact trace according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 1 is a flowchart of a method for extracting, visualizing and verifying copper and lead residues in an impact trace according to an embodiment of the present invention, as shown in fig. 1, the method includes the following steps:
s1: after the first transfer medium pretreated by the alkaline solution is used for carrying out first sampling on the impact trace, a first pre-developing reagent is used for carrying out first color development treatment on the first transfer medium;
s2: judging whether the first color development result accords with a first preset result or not;
if the first color development result accords with a first preset result, preliminarily determining that the impact trace contains copper, and executing S3; if the first color development result does not meet the first preset result, determining that the impact trace does not contain copper, and executing S5;
s3: after the second transfer medium pretreated by the alkaline solution is used for carrying out second sampling on the impact trace, a first verification reagent is used for carrying out second color development treatment on the second transfer medium;
s4: judging whether the second color development result accords with a second preset result or not;
if the second color development result accords with the second preset result, determining that the bullet-sticking trace contains copper, and executing S5; if the second color development result does not meet the second preset result, determining that the impact trace does not contain copper, and executing S5;
s5: after third sampling is carried out on the impact traces by utilizing a third transfer medium pretreated by an acid solution, third color development treatment is carried out on the third transfer medium by adopting a second pre-developing reagent;
s6: judging whether the third color development result accords with a third preset result or not;
if the third color development result accords with a third preset result, primarily determining that the bullet marks contain lead, and executing S7; if the third color development result does not meet the third preset result, determining that the bullet trace does not contain lead, and finishing the identification;
s7: performing fourth color development treatment on the third transfer medium by using a second verification reagent;
s8: judging whether the fourth color development result accords with a fourth preset result or not;
if the fourth color development result accords with the fourth preset result, determining that the bullet traces contain lead, and finishing the identification; and if the fourth color development result does not meet the fourth preset result, determining that the bullet trace does not contain lead, and finishing the identification.
S9: and finishing the identification.
The first pre-development reagent is selected from a solution of a red ammonia acid, the first validation reagent is selected from a solution of 2-nitro-1-naphthol, the second pre-development reagent is selected from a solution of sodium rose bengal, and the second validation reagent is selected from a solution of hydrochloric acid.
For the selective extraction of copper and lead residues in the bullet marks, the invention utilizes the difference of the physical and chemical properties of copper and lead, namely, copper can be dissolved in acid and alkaline solutions at the same time, and lead can be dissolved in the acid solution only. Meanwhile, soft lead is the main component of the bullet core, and the remaining amount of the bullet trace is far larger than that of copper with higher hardness, so that the extraction order of copper residues is determined in preference to lead residues: firstly, pretreating the first transfer medium or the second transfer medium by using an alkaline solution to extract copper residues in the bullet traces for identifying copper, and after the copper residues in the bullet traces are extracted, pretreating the third transfer medium by using an acidic solution to extract lead residues in the bullet traces for identifying lead.
The first pre-developing reagent is selected from a solution of red amino acid, the first validation reagent is selected from a solution of 2-nitro-1-naphthol, and the solution of red amino acid and the solution of 2-nitro-1-naphthol can be respectively used as color developing agents for copper residues in the bullet traces.
Specifically, the first pre-developing reagent, a red ammonia acid solution, can generate a water-insoluble dark green complex with copper under an alkaline condition, and the corresponding first preset result is that the first developing result is dark green. The first validation reagent 2-nitro-1-naphthol solution reacts with copper to form a pink complex, and the corresponding second preset result is that the second color development result is pink.
If a first color development result which appears after the bullet traces are developed by adopting a first pre-developing reagent accords with a first preset result, preliminarily determining that the bullet traces contain copper, and continuing to perform a copper verification step S3; if the first color development result does not meet the first preset result, it is determined that copper does not exist in the impact trace, and the pre-development step S5 of lead can be directly performed.
The copper verification step S3 is to perform second sampling on the bullet traces by using the second transfer medium pretreated by the alkaline solution, perform second color development treatment on the second transfer medium by using a first verification reagent, and determine that the bullet traces contain copper if the second color development result meets a second preset result; and if the second color development result does not accord with the second preset result, determining that no copper exists in the bullet marks. After the verification of the copper residues in the impact traces is completed, the identification of the lead residues in the impact traces can be carried out.
The second pre-developing reagent of the present invention is selected from a sodium rose bengal acid solution, which turns into rosy when the sodium rose bengal acid solution is used to develop lead residues, so that when the second pre-developing reagent is used, the corresponding third predetermined result is a rosy third developing result.
If a third color development result which appears after the bullet traces are developed by adopting a second pre-developing reagent accords with a third preset result, preliminarily determining that the bullet traces contain lead, and continuing to perform a lead verification step S7; and if the third color development result does not meet the third preset result, determining that no lead exists in the bullet traces, and finishing the identification.
The lead verification step S7 is to adopt a second verification reagent hydrochloric acid solution to carry out fourth color development treatment on the third transfer medium, if a fourth color development result accords with a fourth preset result, namely the fourth color development result is bluish purple, the bullet traces can be determined to contain lead, and the identification is finished; if the fourth color development result does not meet the fourth preset result, the bullet marks can be determined to contain no lead, and the identification is finished.
The invention adopts two color development programs in the detection of lead and copper. The first validation reagent 2-nitro-1-naphthol solution and the second validation reagent hydrochloric acid solution are respectively used as validation reagents for the display of copper and lead residues, the effect is to avoid result misjudgment caused by color cognitive difference of an operator and eliminate color interference possibly generated by reaction of other environmental metals except copper and lead and a selected color developing agent, and the possibility of occurrence of false negative and false positive results caused by the color misjudgment can be greatly reduced, so that the reliability of the method and the result is enhanced.
In consideration of the fact that colors and types of shot objects in a gunshot case are different, the transfer medium is adopted to extract metal residues in the shot traces on the shot objects, so that the interference of background colors and patterns of the shot objects and the influence of matrix components of the shot objects can be effectively eliminated, clear and accurate display results are ensured, and the display results are consistent and comparable.
In order to ensure the objectivity and traceability of the visualization result as the forensic evidence application, the visualization result can be selected to be photographed and fixed immediately after each visualization.
In order to eliminate the interference of background factors, the first transfer medium, the second transfer medium and the third transfer medium in the present invention are the same and are selected from one of white cardboard, filter paper, coated paper and printing paper. The colors of transfer printing media such as white cardboard, filter paper, coated paper, printing paper and the like selected by the invention are all white, and the matrix components of the transfer printing media are obviously different from the metal residues of the bullet traces, so that blank contrast can be formed on the colors and the components and the positions where the bullet traces are left; moreover, the medium has good toughness, is not easy to damage in the using process, and can meet the extraction requirement of the concave-convex shape of the bullet traces.
In a specific embodiment, the first sampling comprises: soaking the first transfer medium in an alkaline solution for 10-300s to obtain a uniformly soaked first transfer medium, closely attaching the uniformly soaked first transfer medium to the impact trace, and pressing for 10-300s; and/or, the second sampling comprises: soaking the second transfer printing medium in an alkaline solution for 10-300s to obtain a second transfer printing medium with uniform soaking, closely attaching the second transfer printing medium with uniform soaking to the impact trace, and pressing for 10-300s; and/or, the third sampling comprises: and soaking the third transfer medium in an acid solution for 10-300s to obtain a uniformly soaked third transfer medium, closely attaching the uniformly soaked third transfer medium to the impact trace, and pressing for 10-300s. The sampling mode adopted by the invention can ensure that the copper and lead residues in the impact trace can be relatively completely extracted, and the distribution form of the copper and lead residues can be relatively completely reduced.
In a specific embodiment, the first color development treatment includes: spraying or dropwise adding 0.1-1.0mL of a first pre-developing reagent to the first transfer medium; and/or the second color development treatment comprises the following steps: spraying or dripping 0.1-1.0mL of a first verification reagent to the second transfer medium; and/or, the third color development treatment comprises: spraying or dropwise adding 0.1-1.0mL of second pre-developing reagent to the third transfer medium; and/or the fourth color development treatment comprises: and spraying or dropwise adding 0.1-1.0mL of hydrochloric acid solution to the third transfer medium. The proper amount of the color developing agent can enable the color developing result to be more accurate and reliable, if the amount of the color developing agent is too much, the color of the color developing agent per se can interfere the color developing result, if the amount of the color developing agent is too little, all metals to be detected are difficult to participate in the reaction, and false negative results are easy to occur. If the developer is sprayed excessively carelessly, the transfer medium can be washed with deionized water after color development, and the excessive developer can be washed away.
In a specific embodiment, the first predetermined result is a greenish black color; and/or, the second preset result is pink; and/or, the third predetermined result is rosy; and/or the fourth predetermined result is bluish purple. The preset result is the color of the pre-developing reagent and the verifying reagent which are used by the invention after the copper and the lead have specific color reaction.
In order to obtain better lead extraction and copper extraction effects, an ammonia water solution with the volume concentration of 10-40% can be selected as an alkaline solution; and/or selecting an acetic acid solution with the volume concentration of 10-40% as an acid solution. Specifically, the preparation method of the ammonia water solution comprises the steps of putting 10-40mL of ammonia water into a 100mL volumetric flask, and fixing the volume to a scale by using deionized water; the preparation method of the acetic acid solution comprises the steps of putting 10-40mL of glacial acetic acid into a 100mL volumetric flask, and fixing the volume to the scale with deionized water.
The volume concentration referred to in the present invention is collectively defined as the ratio of the volume of a certain component in 100mL of a solvent.
The tryptophan solution used by the invention is 0.1-0.5% of tryptophan ethanol or methanol solution. The preparation method comprises the following steps: dissolving 0.1-0.5g of erythrosine in 100mL of ethanol or methanol solvent to obtain 0.1-0.5% of methanol or ethanol solution of erythrosine.
The mass concentration referred to in the present invention is defined collectively as the ratio of the mass of a certain component in 100mL of a solvent.
The 2-nitro-1-naphthol solution used in the invention is a 2-nitro-1-naphthol ethanol or methanol solution with a mass concentration of 0.1-0.5%. The preparation method comprises the following steps: dissolving 0.1-0.5g of 2-nitro-1-naphthol in 100mL of ethanol or methanol to obtain a solution of 0.1-0.5% by mass of 2-nitro-1-naphthol in ethanol or methanol.
The sodium rose bengal solution used in the invention is a sodium rose bengal acid aqueous solution with the mass concentration of 0.1-0.5%. The specific configuration method comprises the following steps: 0.1-0.5g of sodium rose bengal, 0.1-0.3g of sodium metabisulfite and 5-10g of polyvinylpyrrolidone are dissolved in 100mL of deionized water to obtain the aqueous solution of the sodium rose bengal. The sodium rose oxide is easy to be oxidized in the air to deteriorate and lose efficacy, the possibility of false negative results is increased, the stability of the sodium rose oxide can be obviously enhanced by adding the antioxidant sodium metabisulfite and the polyvinylpyrrolidone which can generate hydrogen bond action with the sodium rose oxide in the preparation process, the deterioration of the sodium rose oxide is prevented, and the reliability of the color development results is improved.
The volume concentration of the hydrochloric acid solution used in the present invention is 1.0 to 10.0%. The preparation method comprises the following steps: 1-10mL of hydrochloric acid is placed in a 100mL volumetric flask and made up to the mark with deionized water.
The following detailed description will be given to the method for rapidly extracting, visualizing and verifying the metal residues in the bullet traces according to the present invention with reference to the specific examples.
Example 1: extracting, displaying and verifying lead residues in the bullet traces left by the pure lead bullets, and specifically comprises the following steps:
1) A small-caliber sports rifle provided with double-ring pure lead bullets is used for shooting at a shooting distance of 15cm to the white cotton cloth to manufacture a sample of the bullet traces of the pure lead bullets on the white cotton cloth.
2) White cardboard (area is 10 cm)2) Soaking in 15% ammonia water solution, pressing the soaked white cardboard on the bullet traces for 180s with two hands, dripping 1mL of 0.2% ethanol solution of tryptophan by mass on the binding surface of the white cardboard by using a dropper, and after color development is completed, taking a picture to fix the color development result; observing and finding that no dark green mark appears on the white cardboard, so that the bullet trace is determined to contain no copper;
3) Taking the same white cardboard (the area is 10 cm) as the white cardboard obtained in the step 2)2) Soaking in an acetic acid solution with the volume concentration of 15%, attaching the soaked white cardboard on the bullet trace by using two hands, pressing for 180s, dropwise adding 1mL of a sodium rosette aqueous solution with the mass concentration of 0.3% on the attaching surface of the white cardboard by using a dropper, and after color development is completed, taking a picture to fix the color development result; observing and finding that rosy print appears on the white cardboard, so that the preliminarily determined impact trace may contain lead;
4) Dripping 1mL of hydrochloric acid solution with volume concentration of 5.0% by mass on the part of the surface of the white cardboard, which shows a rose-red print, by using a dropper, and after color development is completed, photographing to fix a color development result; the red print part treated by hydrochloric acid on the white cardboard is observed to be changed into blue-purple, thereby determining that the bullet marks contain lead.
The existence of lead and the absence of copper in the bullet traces can be determined from the identification result of the embodiment, and in the step 1), it can be seen that the embodiment is just the bullet trace sample made of the pure lead bullet and is consistent with the identification result.
Example 2: the method comprises the following steps of extracting, displaying and verifying copper and lead residues in bullet traces of armor shells:
1) A64-type 7.62mm pistol and corresponding pistol projectiles (armor projectiles made of copper-zinc alloy wrapped pure lead) are shot at a shooting distance of 15cm towards a steel plate to manufacture a sample of armor projectile impact traces on the steel plate.
2) Printing photographic paper (area 15 cm)2) Soaking in an ammonia water solution with the volume concentration of 25%, sticking the front side of the soaked printing paper on the bullet trace by using two hands, pressing for 100s, spraying 1mL of 0.2% by mass concentration ethanol solution of the tryptophan on the front side of the printing paper by using a spray bottle, and after color development is completed, taking a picture to fix the color development result; the printed photographic paper was observed to have a greenish black print on the front side, so that the copper content in the impact trace was preliminarily determined.
3) Taking the same printing photographic paper (the area is 15 cm) as the step 2)2) Soaking in 25% ammonia water solution, pressing the front side of the soaked printing paper on the bullet trace for 100s with two hands, spraying 1mL of 0.2% by mass 2-nitro-1-naphthol methanol solution on the front side of the printing paper by using a spray bottle, and taking a picture to fix the color development result after the color development is complete; observing and finding that pink marks appear on the front surface of the printing paper, so that the bullet marks are determined to contain copper;
4) Taking the same printing photographic paper (with the area of 15 cm) as the step 2)2) Soaking in 20% acetic acid solution, pressing the front surface of the soaked printing paper on the bullet trace for 100s, spraying 1mL of 0.3% aqueous solution of sodium rose red acid with mass concentration on the front surface of the printing paper by using a spray bottle, and taking a picture to fix the color development result after the color development is completed; observing and finding that the rose red print appears on the front surface of the printing photographic paper, so that the preliminarily determined impact trace may contain lead;
5) Dripping 1mL of hydrochloric acid solution with volume concentration of 5.0% by mass concentration on the part of the printing paper on which the rose-red print appears by using a dropper, and photographing to fix a color development result after the color development is completed; the red print portion of the printed photographic paper treated with hydrochloric acid was observed to turn bluish purple, thereby confirming that the bullet marks contain lead.
From the identification result of this embodiment, it can be determined that copper and lead exist in the bullet trace at the same time, and it can be seen from step 1) that this embodiment is the sample of the bullet trace made of the copper armor warhead, which is consistent with the identification result.
Example 3: extracting, displaying and verifying blank impact traces, which comprises the following steps:
1) White cotton cloth was selected as a blank bullet mark sample.
2) Filter paper (area 20 cm)2) Soaking in 30% ammonia water solution, pressing the soaked filter paper on the bullet trace for 60s with two hands, spraying 1mL of 0.1% tryptophan methanol solution on the filter paper by using a spray bottle, and taking a picture to fix the color development result after the color development is complete; the filter paper was observed to have no greenish black print, so that the bullet marks were determined to be free of copper.
3) Taking the same filter paper (20 cm in area) as in step 2)2) Soaking in an acetic acid solution with the volume concentration of 15%, sticking the soaked filter paper on the bullet trace by hands, pressing for 60s, spraying 1mL of a sodium rosette aqueous solution with the mass concentration of 0.2% on the filter paper by using a spray bottle, and after color development is completed, taking a picture to fix the color development result; no rose-red blots were observed on the filter paper, so that no lead was contained in the bullet traces.
From the identification result of this example, it can be determined that the sample does not contain copper and lead, and in step 1), it can be seen that this example is a blank bullet trace sample made of white cotton cloth, which is consistent with the identification result.
Example 4: extracting, displaying and verifying the bullet traces, which comprises the following steps:
1) And selecting an iron rod to forcibly scratch on the pine board at a certain inclination angle to prepare a trace iron residue on the pine board as a bullet trace interference sample.
2) Combining coated paper (area is 10 cm)2) Soaking in 25% ammonia water solution, and sticking the front of the coated paper on the bullet trace with two handsPressing for 90s, spraying 1mL of 0.2 mass percent methanol solution of the tryptophan on the front surface of the coated paper by using a spray bottle, and photographing to fix a color development result after the color development is completed; the coated paper was observed to have no greenish black mark, so that it was determined that the impact mark contained no copper.
3) Taking the same coated paper (with the area of 10 cm) as the step 2)2) Soaking in 25% acetic acid solution, pressing the front surface of the soaked coated paper on the bullet trace for 90s by hand, spraying 1mL of 0.2% aqueous solution of rose sodium acid with mass concentration on the front surface of the coated paper by using a spray bottle, and after complete color development, photographing and fixing the color development result; no rose-red mark appears on the coated paper, so that the mark is determined to contain no lead.
From the identification result of this example, it can be determined that the sample does not contain copper and lead, and in step 1), it can be seen that the sample is just interfered by the bullet trace made of the iron rod, which is consistent with the identification result.
In conclusion, the method can rapidly and reliably obtain the qualitative result, the distribution position and the distribution morphological characteristics of the copper and lead residues in the bullet traces on site, and can be used for rapidly determining whether the bullet traces are the bullet traces, analyzing the bullet types and judging the shooting distance on site, thereby providing investigation clues and court evidences for the gun-related events in time.
The above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and these modifications or substitutions do not depart from the spirit of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for extracting, showing and verifying copper and lead residues in bullet traces is characterized by comprising the following steps:
1) After a first sample is carried out on the impact trace by using a first transfer medium pretreated by an alkaline solution, a first pre-developing reagent is adopted to carry out first color development treatment on the first transfer medium;
2) If the first color development result accords with a first preset result, preliminarily determining that the impact trace contains copper, and executing the step 3); or if the first color development result does not accord with the first preset result, determining that the bullet trace contains no copper, and executing the step 5);
3) After second sampling is carried out on the impact trace by using a second transfer medium pretreated by an alkaline solution, second color development treatment is carried out on the second transfer medium by using a first verification reagent;
4) If the second color development result accords with a second preset result, determining that the bullet-striking trace contains copper; or if the second color development result does not accord with the second preset result, determining that the bullet-marked trace does not contain copper;
5) Thirdly sampling the impact trace by using a third transfer medium pretreated by an acid solution, and then carrying out third color development treatment on the third transfer medium by using a second pre-developing reagent;
6) If the third color development result accords with a third preset result, preliminarily determining that the bullet traces contain lead, and executing the step 7); or if the third color development result does not meet a third preset result, determining that the bullet-marked trace does not contain lead;
7) Performing fourth color development treatment on the third transfer medium by using a second verification reagent;
8) If the fourth color development result accords with a fourth preset result, determining that the bullet-marked trace contains lead; or if the fourth color development result does not accord with the fourth preset result, determining that the bullet-marked trace does not contain lead;
wherein the first pre-development reagent is selected from a solution of a rhodomine, the first validation reagent is selected from a solution of 2-nitro-1-naphthol, the second pre-development reagent is selected from a solution of sodium rhodizonate, and the second validation reagent is selected from a solution of hydrochloric acid.
2. The method for extracting, revealing and verifying copper and lead residues in an impact mark according to claim 1, wherein the first transfer medium, the second transfer medium and the third transfer medium are the same and are selected from one of white cardboard, filter paper, coated paper and printing photographic paper.
3. The method for extracting, visualizing and verifying copper and lead residues in bullet trails according to claim 1, wherein said first sampling comprises: soaking the first transfer medium in an alkaline solution for 10-300s to obtain a uniformly soaked first transfer medium, tightly attaching the uniformly soaked first transfer medium to the impact trace, and pressing for 10-300s; and/or the presence of a gas in the gas,
the second sampling comprises: soaking the second transfer printing medium in an alkaline solution for 10-300s to obtain a second transfer printing medium with uniform soaking, closely attaching the second transfer printing medium with uniform soaking to the impact trace, and pressing for 10-300s; and/or the presence of a gas in the gas,
the third sampling comprises: and soaking the third transfer medium in an acid solution for 10-300s to obtain a uniformly soaked third transfer medium, closely attaching the uniformly soaked third transfer medium to the impact trace, and pressing for 10-300s.
4. The method for extracting, visualizing and verifying copper and lead residues in bullet-imprints according to claim 1, wherein the first visualization process comprises: spraying or dripping 0.1-1.0mL of the first pre-developing reagent to the first transfer medium; and/or the presence of a gas in the atmosphere,
the second color development processing includes: spraying or dripping 0.1-1.0mL of the first verification reagent to the second transfer medium; and/or the presence of a gas in the gas,
the third color development processing includes: spraying or dropwise adding 0.1-1.0mL of the second pre-developing reagent to the third transfer medium; and/or the presence of a gas in the gas,
the fourth color development processing includes: and spraying or dropwise adding 0.1-1.0mL of the second validation reagent to the third transfer medium.
5. The method for extracting, visualizing and verifying copper and lead residues in bullet traces according to claim 1, wherein said first predetermined result is a greenish black color; and/or the presence of a gas in the gas,
the second preset result is pink; and/or the presence of a gas in the gas,
the third predetermined result is rosy; and/or the presence of a gas in the atmosphere,
the fourth predetermined result is bluish purple.
6. The method for extracting, visualizing and verifying copper and lead residues in bullet traces according to claim 1 or 3, wherein the alkaline solution is an ammonia solution with a volume concentration of 10-40%; and/or the presence of a gas in the atmosphere,
the acid solution is an acetic acid solution with the volume concentration of 10-40%.
7. The method for extracting, visualizing and verifying the copper and lead residues in the bullet-stuck marks according to claim 1, wherein the solution of the erythrosine acid is 0.1-0.5% by mass of ethanol or methanol solution of the erythrosine acid.
8. The method for extracting, revealing and verifying copper and lead residues in bullet traces according to claim 1, wherein the 2-nitro-1-naphthol solution is a 2-nitro-1-naphthol ethanol or methanol solution with a mass concentration of 0.1-0.5%.
9. The method for extracting, visualizing and verifying copper and lead residues in bullet traces according to claim 1, wherein the sodium rose bengal solution is 0.1-0.5% by mass of sodium rose bengal solution.
10. The method for extracting, visualizing and verifying the copper and lead residues in the bullet trails according to claim 1, wherein the volume concentration of the hydrochloric acid solution is 1.0-10.0%.
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| CN1135603A (en) * | 1995-05-11 | 1996-11-13 | 南京铁道医学院 | Method for making fifteen kinds of test paper for quickly testing common chemical contamination in food |
| US6248593B1 (en) * | 1997-06-11 | 2001-06-19 | The United States Of America As Represented By The Department Of Health And Human Services | Handwipe disclosing method for the presence of lead |
| CN110132957A (en) * | 2019-06-18 | 2019-08-16 | 中国人民公安大学 | A kind of general process for show of human skin surface's common metal trace |
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| US6800485B2 (en) * | 1998-12-03 | 2004-10-05 | Sandra Lynn Cole | Chemical spot test for lead in paint and other media |
| US11442049B2 (en) * | 2019-07-25 | 2022-09-13 | Frederic G Dewalt | Method for producing a purple complex for the presence of lead using sodium rhodizonate without use of strong acid |
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| CN1135603A (en) * | 1995-05-11 | 1996-11-13 | 南京铁道医学院 | Method for making fifteen kinds of test paper for quickly testing common chemical contamination in food |
| US6248593B1 (en) * | 1997-06-11 | 2001-06-19 | The United States Of America As Represented By The Department Of Health And Human Services | Handwipe disclosing method for the presence of lead |
| CN110132957A (en) * | 2019-06-18 | 2019-08-16 | 中国人民公安大学 | A kind of general process for show of human skin surface's common metal trace |
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