CN102519955B - Measuring method for gun shooting time - Google Patents
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- CN102519955B CN102519955B CN201110441435.6A CN201110441435A CN102519955B CN 102519955 B CN102519955 B CN 102519955B CN 201110441435 A CN201110441435 A CN 201110441435A CN 102519955 B CN102519955 B CN 102519955B
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Abstract
Provided is a measuring method for gun shooting time. On the condition of acetic acid (HAC), nitrite and sulfanilic acid (SN) have a diazo reaction and then couple with alpha-naphthylamine (NC) for coloration. Based on the light absorption characteristic of the product, spectrophotometry is adopted to measure the content of nitrite in shooting residue. The residue in a gun barrel obtained at different time after shooting is extracted for analysis, a relation curve of the content of nitrite and shooting time is obtained, and thus gun shooting time is determined. The measuring method for gun shooting time is capable of providing an effective method for detection of gun shooting time, causes no damage to a gun on the premise of guaranteeing extraction effect, has the advantages of being accurate, fast, high in sensitivity, good in stability, reliable in results and the like, and meets the requirements for detection and scientific research of gun shooting time.
Description
Technical field
The invention belongs to the technical field that shooting residue analysis and shooting time detect, specifically refer to by measuring the content of gun shooting residue nitrite, and by the relation of this content and time, determine the shooting time of gun.
Technical background
The shooting residue complicated of gun, not only content is in trace or trace level, and different for the detection method of different component; China mainly concentrates on qualitative analysis about the detection of shooting residue nitrite at present, to quantitative test, pay close attention to less, apply its content relation detection over time shooting time and have no report, from extraction conditions the determining also not compared with proven technique and method to shooting time of the residual nitrite of gun inwall.
In recent years, gun-related case has the trend of increasing, and along with scientific and technical development and progress, suspect's counter-reconnaissance consciousness strengthens, for traditional material evidences such as the fingerprint of solving criminal cases, bullet shell cases, be difficult to obtain and identify, this just makes the importance that suspicion gun are detected day by day highlight, and shoots the mensuration of residue nitrite determine shooting time by gun, for cracking of cases and court judgment, has important evidential function.Yet, from current existing nitrite assay method, mostly be the content of nitrite of measuring in food or process water, as described below:
Application number is the patent of 201010526803.2 " assay methods of water base metal cleaning agent nitrite ", application number is the patent of 90102835.5 " assay methods of nitrite ion ", " Determination of Trace Nitrite in Food " paper in the 3rd > > of phase < < spectrographic laboratory in 2009, the 4th phase < < in 2011 meticulous with specialty chemicals > > in " mensuration of nitrite in food " paper, within 2010, " mensuration of Trace Nitrite in water quality " paper in > > etc. is brewageed by the 6th phase < < China, wherein said assay method, all " trace " content of nitrite in food or water is measured, and processing in the early stage of its sample is also comparatively complicated.
Content of nitrite assay method in food, service water, the assay method of the water quality nitrites such as surface water, is not all suitable for the content of nitrite of shooting in residue and measures, this be because:
(1) the matrix composition composition of above-mentioned these determinands differs larger with the constituent of shooting residue, and the earlier stage processing method of sample to be tested is also different, and is unsuitable for shooting extraction and the pre-service of residue sample;
(2) content of shooting residue nitrite is compared with food, and the former content is low.Therefore experiment condition and the working curve of the above-mentioned assay method for food " trace " nitrite, can not meet the mensuration of shooting residue nitrite.
At present about the detection of shooting residue nitrite, generally only have or the qualitative analysis of nothing; About detecting the shooting time of gun, can only provide the conclusion of whether pulling the trigger in three days at approximate range, error is larger, and accuracy is not high.
Therefore, how applying high-sensitive method and detect content of nitrite the Accurate Determining shooting time in shooting residue, is a problem demanding prompt solution.
Summary of the invention
In order to solve the problems of the technologies described above, the invention provides a kind of assay method of shooting residue nitrite; The present invention is by the corresponding relation of residue nitrite and shooting time, shooting time that can Accurate Determining gun; The present invention guaranteeing accurately under prerequisite, to gun without any infringement; The present invention has highly sensitive, good stability, and features such as reliable results, and simple and quick, meet the needs of routine check and scientific research.
In order to realize foregoing invention object, the present invention adopts technical scheme as described below:
A kind of assay method of gun shooting time, under acetic acid (HAC) condition, nitrite and sulfanilic acid (SN) in shooting residue carry out diazo-reaction, again with alpha-naphthylamine (NC) coupling colour development, adopt Spectrophotometric Determination of Nitrite content, draw absorbance-content of nitrite typical curve; After extracting shooting, shooting residue corresponding to different time analyzed, and obtains the relation of absorbance and shooting time, through typical curve, the change curve of this absorbance-time is converted to the relation curve of content of nitrite-shooting time; The absorbance of mensuration suspicion gun shooting residue extract, and obtain corresponding content of nitrite from described typical curve, utilize content of nitrite-shooting time relation curve to determine the shooting time of gun; Concrete steps are as follows:
(1) shooting residue extracting method: pure water rinsing gun inwall extracts shooting residue;
(2) determining of experiment condition:
A. agents useful for same of the present invention is: sodium nitrite, glacial acetic acid, sulfanilic acid, alpha-naphthylamine; Its Sodium Nitrite is that top grade is pure, and all the other reagent are pure for analyzing;
B. maximum absorption wavelength: do not shoot the extract of gun inwall by pure water rinsing as constant volume liquid S, and add therein glacial acetic acid and developer as reference liquid; In 505-555nm wavelength coverage, measure the absorbance of sodium nitrite standard solution: obtaining maximum absorption wavelength scope is 515-525nm;
C. glacial acetic acid and consumption thereof: to coloring reaction system, add respectively the glacial acetic acid of different volumes, carry out chromogenic reaction and absorbance measurement, the consumption that obtains glacial acetic acid is 0.1-0.6mL;
D. the consumption of sulfanilic acid (SN): SN is developer; Use respectively 1 * 10 of different volumes
-2the sulfanilic acid solution of mol/L carries out chromogenic reaction and absorbance measurement, and the consumption that obtains SN is 1-10mL;
E. the consumption of alpha-naphthylamine (NC): NC is developer; Use respectively 1 * 10 of different volumes
-3mol/L alpha-naphthylamine solution carries out chromogenic reaction and absorbance measurement, and the consumption that obtains NC is 5-15mL;
F. the stability of chromogenic reaction, passes through experiment, and be 30-120 minute the stabilization time of nitrite ion and reference liquid;
(3) disturbing factor is eliminated: by pure water rinsing, do not shoot the extract of gun as the constant volume liquid S of typical curve liquid to be measured and reference liquid, eliminated the background interference of other compositions in gun shooting residue; By nitrate mark-on method, test, prove that the oxidation product nitrate of nitrite is noiseless to the mensuration of nitrite;
(4) analyzing detecting method:
A. working fluid preparation: prepare 5 * 10
-3the acetum of the sulfanilic acid of mol/L, is called SN working fluid by this solution, the acetic acid that is wherein 1% containing volume ratio; Preparation 1 * 10
-3the acetum of mol/L alpha-naphthylamine, is called NC working fluid by this solution, the acetic acid that is wherein 1% containing volume ratio; By pure water rinsing, do not shoot the extract of gun as constant volume liquid S;
B. the processing of sample: the inwall that uses 100mL-150mL pure water rinsing shooting gun, extract proceeds in 250mL volumetric flask, adds NC working fluid described in SN working fluid described in 25mL, 25mL, uses pure water constant volume, shake up rear placement 30-120 minute, at wavelength 515-525nm place, measure absorbance; This liquid is testing sample nitrite ion;
C. typical curve: prepare 1 * 10
-4the standard solution of mol/L sodium nitrite; In being numbered 7 10mL volumetric flasks of 1-7, add SN working fluid, each 1mL of NC working fluid, add respectively 1 * 10
-4mol/L NaNO
2standard solution 0mL, 0.1mL, 0.2mL, 0.4mL, 0.6mL, 0.8mL, 1.0mL; With described constant volume liquid S constant volume, shake up latter standing 30-120 minute and measure absorbance; This serial solution is typical curve nitrite ion to be measured;
D. absorbance is measured: adopt spectrophotometer, 1cm cuvette, at wavelength 515-525nm place, measures the absorbance of described typical curve nitrite ion to be measured and testing sample nitrite ion; The absorbance of described typical curve nitrite ion to be measured of take is drawn the typical curve of absorbance-nitrite concentration as ordinate, the concentration of nitrite of take are horizontal ordinate;
E. from described typical curve, try to achieve the content of nitrite of testing sample: from described typical curve, can obtain: the concentration of the sodium nitrite corresponding with ordinate absorbance is 1 * 10
-5in mol/L, meet lambert-Beer law, linear equation is: A=28047x+0.001, linearly dependent coefficient R=0.9995;
F. content of nitrite-shooting time relation curve: 0h, 2h, 4h, 8h, 12h, 24h, 36h, 48h, 72h, 120,168h obtain nitrite extract to be measured with pure water rinsing gun inwall after shooting respectively, it at wavelength, is the absorbance of different time gun extract after 515-525nm place measures shooting, from described typical curve, try to achieve the nitrite concentration that each absorbance is corresponding, different time after drafting shooting and the relation curve of extract nitrite, this is content of nitrite-shooting time relation curve;
G. mensuration suspicion is shot the absorbance of gun extract, and obtains corresponding content of nitrite from typical curve, utilizes content of nitrite-shooting time relation curve to determine the shooting time of gun.
(5) determination of recovery rates: in 100mL volumetric flask, add respectively sodium nitrite standard solution, glacial acetic acid and developer, making content of nitrite is 1 * 10
-6mol/L, 2 * 10
-6mol/L, 4 * 10
-6mol/L.In described constant volume liquid S, add glacial acetic acid and developer as reference, record respectively absorbance and be: 0.0285(A), 0.0582(A), 0.1152(A); From described typical curve, trying to achieve corresponding content of sodium nitrite is respectively: 9.8 * 10
-7mol/L, 2.04 * 10
-6mol/L, 4.07 * 10
-6mol/L; Obtain the recovery of the method mensuration shooting residue nitrite between 98%-102%, can meet the requirement of shooting time mensuration and scientific research.
The present invention utilizes the nitrite in shooting residue in air, to be oxidized to gradually nitrate, the redox characteristic that nitrate residue reduces gradually with the prolongation of shooting rear interval time; Utilize nitrite to react with primary aromatic amine under acid condition and generate diazo salt, diazo salt and aromatic amine compounds coupling generate the development properties of purple azo-compound; Extract the residue of the rear different time of shooting, through chemical reaction, develop the color, by the absorbance of spectrophotometric determination extract, obtain absorbance with the variation relation of shooting time, the relation curve that is content of nitrite-shooting time by the relationship conversion of this absorbance-time by typical curve; The absorbance of mensuration suspicion gun residue extract, can determine content of nitrite and corresponding shooting time.The concrete beneficial effect of the present invention is as follows:
1. the present invention, for measuring the shooting time of gun, is detected by spectrophotometric method, and accurate quick, can improve detection efficiency greatly;
2. the present invention uses the extract of not shooting gun (containing nitrite) with pure water rinsing to carry out constant volume in the drafting of typical curve, makes typical curve consistent with the system of extract to be determined, has guaranteed the accuracy of measurement result;
3. the present invention, by the mensuration of shooting residue nitrite being determined to the shooting time of gun, is guaranteeing under the prerequisite of accuracy, method to gun itself without any infringement;
4. assay method of the present invention, the shooting residue solution extracting when suspicion gun are arrested of take is sample, carries out the mensuration of shooting time, has avoided finding the difficulty of traditional material evidences such as fingerprint, bullet shell case;
5. detection method of the present invention, has the features such as highly sensitive, good stability, reliable results, and simple and quick, meets the needs of routine check and scientific research.
Embodiment
Disclose object of the present invention and be intended to protect all changes and improvements in the scope of the invention, the following examples are not limitation of the invention.By the following examples, can explain in more detail the present invention.
A kind of assay method of gun shooting time, under acetic acid (HAC) condition, nitrite and sulfanilic acid (SN) in shooting residue carry out diazo-reaction, again with alpha-naphthylamine (NC) coupling colour development, adopt Spectrophotometric Determination of Nitrite content, draw absorbance-content of nitrite typical curve; After extracting shooting, shooting residue corresponding to different time analyzed, and obtains the variation relation of absorbance and shooting time, the relation curve that is content of nitrite-shooting time by the relationship conversion of this absorbance-time through typical curve; The absorbance of mensuration suspicion shooting gun extract, and obtain corresponding content of nitrite from described typical curve, utilize content of nitrite-shooting time relation curve to determine the shooting time of gun; Concrete steps are as follows:
(1) determining of shooting residue extracting method: utilize the water-soluble characteristic of nitrite: a. to use pure water rinsing gun inwall, extract shooting residue; B. utilize absorbent cotton to dip in pure water wiping gun barrel inwall, extract shooting residue; C. use dry rayon balls wiping gun barrel inwall, extract shooting residue.Experimental result shows: a method extraction effect is best, so the present invention adopts pure water rinsing gun inwall to extract shooting residue.
(2) determining of experiment condition:
A. agents useful for same of the present invention is: sodium nitrite, glacial acetic acid, sulfanilic acid, alpha-naphthylamine; Its Sodium Nitrite is that top grade is pure, and all the other reagent analysis are pure; By pure water rinsing, do not shoot the extract of gun as constant volume liquid S; Analytical instrument is Agilent8453 ultraviolet-visible spectrophotometer (U.S.), Denver SI-234 analytical balance (U.S.), and gun are domestic standard 64 formula pistols.
B. maximum absorption wavelength: in being numbered two 100mL volumetric flasks of 1,2, do not add sodium nitrite standard solution No. 1, add 1mL sodium nitrite standard solution for No. 2, in two bottles, respectively add glacial acetic acid 0.10,0.20,0.40 or 0.60mL, sulfanilic acid solution 1,5 or 10mL, alpha-naphthylamine solution 5,10 or 15mL, with described constant volume liquid S constant volume to 100mL, shake up, place 30,45,60,75,90,105 or 120 minutes; In 505-555nm wavelength coverage, the solution of take in headpin is reference, measures the absorbance of nitrite ion in No. 2 bottles with lcm cuvette, and absorbance maximum and stable absorbing wavelength are 515-525nm, and optimum absorb wavelength is 520nm.Under equal conditions, with the shooting gun actual sample extract of latter 2 hours, verify, result is coincide.
C. glacial acetic acid consumption: in the volumetric flask of 8 100mL that is numbered 1-8, respectively add 1mL sodium nitrite standard solution, add respectively glacial acetic acid 0, 0.05, 0.10, 0.20, 0.40, 0.60, 0.80, 1.00mL, add sulfanilic acid solution 1, 5 or 10mL, alpha-naphthylamine solution 5, 10 or 15mL, with described constant volume liquid S constant volume to 100mL, shake up, place 30, 45, 60, 75, 90, 105 or 120 minutes, the solution of take in headpin is reference, at wavelength, it is 515-525nm place, with 1cm cuvette, measure the absorbance of nitrite ion, experiment determines that the scope that adds of glacial acetic acid is 0.1-0.6mL, optimum amount is 0.2mL.Under equal conditions, with the shooting gun actual sample extract of latter 2 hours, verify, result is coincide.
D. the consumption of sulfanilic acid (SN): SN is developer, in the volumetric flask of 6 100mL that is numbered 1-6, respectively add 1mL sodium nitrite standard solution, add glacial acetic acid 0.10, 0.20, 0.40 or 0.60mL, alpha-naphthylamine solution 5, 10 or 15mL, add respectively sulfanilic acid solution 0, 0.1, 0.5, 1, 5, 10mL, with described constant volume liquid S constant volume to l00mL, shake up, place 30, 45, 60, 75, 90, 105 or 120 minutes, the solution of take in headpin is reference, at wavelength, it is 515-525nm place, with 1cm cuvette, measure the absorbance of nitrite ion, experiment determines that the addition of sulfanilic acid solution is 1-10mL, optimum amount is 5mL.Under equal conditions, with the shooting gun actual sample of latter 2 hours, verify, result is coincide.
E. the consumption of alpha-naphthylamine (NC): NC is developer, in the volumetric flask of 8 100mL that is numbered 1-8, respectively add 1mL sodium nitrite standard solution, add glacial acetic acid 0.10, 0.20, 0.40 or 0.60mL, add sulfanilic acid solution 1, 5 or 10mL, add respectively alpha-naphthylamine solution 0, 0.l, 0.5, 1, 5, 10, 15, 30mL, with described constant volume liquid S constant volume to l00mL, shake up, place 30, 45, 60, 75, 90, 105 or 120 minutes, the solution of take in headpin is reference, at wavelength 515-525nm place, with 1cm cuvette, measure the absorbance of nitrite ion, experiment determines that the consumption of alpha-naphthylamine solution is 5-15mL, optimum amount is 10mL.Under equal conditions, with the shooting gun actual sample of latter 2 hours, verify, result is coincide.
F. the stability of chromogenic reaction, be numbered 1, in two l00mL volumetric flasks of 2, do not add sodium nitrite standard solution No. 1, add 1mL sodium nitrite standard solution for No. 2, respectively add glacial acetic acid 0.10, 0.20, 0.40 or 0.60mL, add sulfanilic acid solution 1, 5 or 10mL, alpha-naphthylamine solution 5, 10 or 15mL, with described constant volume liquid S constant volume to l00mL, shake up, the solution of take in headpin is reference, at wavelength 515-525nm place, with 1cm cuvette, measure the absorbance of differential responses time nitrite ion, experiment determines that the stable reaction time is 30-120 minute, consider detection efficiency, select the chromogenic reaction stabilization time of 30 minutes.Under equal conditions, with the shooting gun actual sample of latter 2 hours, verify, result is coincide.
(3) disturbing factor is eliminated: by pure water rinsing, do not shoot the extract of gun as the constant volume liquid S of typical curve liquid to be measured and reference liquid, eliminated the background interference of other compositions in gun shooting residue; By nitrate mark-on method, test, prove that the oxidation product nitrate of nitrite is noiseless to the mensuration of nitrite.
(4) analyzing detecting method:
A. working fluid preparation: prepare 5 * 10
-3the acetum of the sulfanilic acid of mol/L, is called SN working fluid by this solution, the acetic acid that is wherein 1% containing volume ratio; Preparation 1 * 10
-3the acetum of mol/L alpha-naphthylamine, is called NC working fluid by this solution, the acetic acid that is wherein 1% containing volume ratio; By pure water rinsing, do not shoot the extract of gun as constant volume liquid S.
B. the processing of sample: the inwall that uses 100mL-150mL pure water rinsing shooting gun, extract proceeds in 250mL volumetric flask, add NC working fluid described in SN working fluid described in 25mL, 25mL, with pure water constant volume to 250mL, shake up rear placement 30-120 minute, at wavelength 515-525nm place, measure absorbance; This liquid is testing sample nitrite ion.
C. typical curve: prepare 1 * 10
-4the standard solution of mol/L sodium nitrite; In being numbered 7 10mL volumetric flasks of No. 1-7, add described SN working fluid, each 1mL of NC working fluid, add respectively 1 * 10
-4mol/L NaNO
2standard solution 0mL, 0.1mL, 0.2mL, 0.4mL, 0.6mL, 0.8mL, 1.0mL; With described constant volume liquid S constant volume, shake up rear standing 30-120 minute, the solution of take in headpin is reference, measures the absorbance of serial nitrite ion in 2-7 bottle at wavelength 515-525nm place; This serial solution is typical curve nitrite ion to be measured.
D. absorbance is measured: adopt described spectrophotometer, 1cm cuvette, at wavelength 515-525nm place, measures the absorbance of described typical curve series nitrite ion and testing sample nitrite ion; Take described typical curve series nitrite ion absorbance as ordinate, the concentration of nitrite of take be the typical curve that horizontal ordinate is drawn absorbance-nitrite concentration.Absorbance measurement result corresponding to different nitrite concentrations listed in table 1:
The absorbance that the different nitrite concentrations of table 1 are corresponding
| Add NaNO 2Volume (mL) | 0 | 0.1 | 0.2 | 0.4 | 0.6 | 0.8 | 1.0 |
| NaNO 2Concentration (1 * 10 -6mol/L） | 0 | 1 | 2 | 4 | 6 | 8 | 10 |
| Absorbance (A) | 0 | 0.0295 | 0.0628 | 0.108 | 0.1688 | 0.2255 | 0.2831 |
E. from described typical curve, try to achieve the content of nitrite of testing sample: from described typical curve, can obtain: the concentration of the sodium nitrite corresponding with ordinate absorbance is 1 * 10
-5in mol/L, meet lambert-Beer law, linear equation is: A=28047x+0.001, linearly dependent coefficient R=0.9995;
F. content of nitrite-shooting time relation curve: in 11 250mL volumetric flasks, respectively add glacial acetic acid 0.25-1.5mL, sulfanilic acid solution 10-20mL, alpha-naphthylamine solution 12.5-37.5mL; 0h, 2h, 4h, 8h, 12h, 24h, 36h, 48h, pure water rinsing gun barrel inwall for 72h, 120,168h after shooting respectively, extract is moved into volumetric flask, after constant volume, shake up, in constant volume liquid S, add the glacial acetic acid of equivalent and developer as reference liquid, at wavelength, it is 515-525nm place, with 1cm cuvette, measure the absorbance of the rear different time extract of shooting, obtain absorbance with the variation relation of shooting time, the relation curve that is content of nitrite-shooting time by the relationship conversion of this absorbance-time by typical curve; The absorbance of mensuration suspicion gun residue extract, can determine content of nitrite and corresponding shooting time.
(5) determination of recovery rates: in 3 100mL volumetric flasks, add respectively sodium nitrite standard solution, glacial acetic acid and developer, making content of nitrite is 1 * 10
-6mol/L, 2 * 10
-6mol/L, 4 * 10
-6mol/L; In described constant volume liquid S, add glacial acetic acid and developer as reference, record respectively absorbance and be: 0.0285(A), 0.0582(A), 0.1152(A); From described typical curve, trying to achieve corresponding content of sodium nitrite is respectively: 9.8 * 10
-7mol/L, 2.04 * 10
-6mol/L, 4.07 * 10
-6mol/L; The present invention measures the recovery of shooting residue nitrite between 98%-102%, can meet the requirement of shooting time detection and scientific research.
Press the operation of above-described embodiment step, use 8 six or four formula pistols, carry out respectively replication 8 times, will measure the table 2 that the results are shown in of shooting time.
The replicate determination result of table 2 shooting time
As shown in table 2, measurement result is very approaching, illustrates that the present invention has advantages of favorable reproducibility about the assay method of shooting time.Therefore, by the checking of above-mentioned embodiment, can find out that method that the present invention measures shooting time has precision high, favorable reproducibility, the advantage such as measurement result is accurate.
Claims (2)
1. the assay method of a gun shooting time, it is characterized in that: under acetic acid condition, nitrite and sulfanilic acid in the shooting residue of gun carry out diazo-reaction, again with alpha-naphthylamine coupling colour development, adopt Spectrophotometric Determination of Nitrite content, draw absorbance-content of nitrite typical curve; Extract the shooting residue of the gun that the rear different time of shooting is corresponding and analyze, obtain the relation of absorbance and shooting time, by aforesaid standards curve, the change curve of absorbance-shooting time is converted to content of nitrite-shooting time relation curve; The absorbance of the shooting residue extract of mensuration suspicion gun, and obtain corresponding content of nitrite from described typical curve, utilize content of nitrite-shooting time relation curve to determine the shooting time of suspicion gun; Concrete steps are as follows:
(1) shooting residue extracting method: pure water rinsing gun inwall extracts shooting residue;
(2) determining of experiment condition:
A. the assay method agents useful for same of described gun shooting time is: sodium nitrite, glacial acetic acid, sulfanilic acid, alpha-naphthylamine; Its Sodium Nitrite is that top grade is pure, and all the other reagent are pure for analyzing; By pure water rinsing, do not shoot the extract of gun as constant volume liquid S;
B. maximum absorption wavelength: using do not shoot gun extract as reference liquid; In this shoots the extract of gun, do not add sodium nitrite standard solution, in 505-555nm wavelength coverage, measure absorbance: obtaining maximum absorption wavelength scope is 515-525nm;
C. glacial acetic acid consumption: add respectively the glacial acetic acid of different volumes to coloring reaction system, carry out chromogenic reaction and absorbance measurement, the consumption that obtains glacial acetic acid is 0.1-0.6mL;
D. the consumption of sulfanilic acid: sulfanilic acid is developer; Use respectively 1 * 10 of different volumes
-2mol/L sulfanilic acid solution carries out chromogenic reaction and absorbance measurement, and the consumption that obtains sulfanilic acid is 1-10mL;
E. the consumption of alpha-naphthylamine: alpha-naphthylamine is developer; Use respectively 1 * 10 of different volumes
-3the alpha-naphthylamine solution of mol/L carries out chromogenic reaction and absorbance measurement, and the consumption that obtains alpha-naphthylamine is 5-15mL;
F. the stability of chromogenic reaction, passes through experiment, and be 30-120 minute the stabilization time of nitrite ion and reference liquid;
(3) disturbing factor is eliminated: by pure water rinsing, do not shoot the extract of gun as the constant volume liquid S of typical curve liquid to be measured and the constant volume liquid S of reference liquid, eliminated the background interference of other compositions in the shooting residue of gun; By nitrate mark-on method, test, prove that the oxidation product nitrate of nitrite is noiseless to the mensuration of nitrite;
(4) analyzing detecting method:
A. working fluid preparation: prepare 5 * 10
-3the acetum of the sulfanilic acid of mol/L, is called SN working fluid by this solution, the acetic acid that is wherein 1% containing volume ratio; Preparation 1 * 10
-3the acetum of mol/L alpha-naphthylamine, is called NC working fluid by this solution, the acetic acid that is wherein 1% containing volume ratio; By pure water rinsing, do not shoot the extract of gun as constant volume liquid S;
B. the processing of sample: the inwall that uses 100mL-150mL pure water rinsing suspicion gun, extract proceeds in 250mL volumetric flask, adds NC working fluid described in SN working fluid described in 25mL, 25mL, uses pure water constant volume, shake up rear placement 30-120 minute, at wavelength 515-525nm place, measure absorbance; This liquid is the nitrite ion of testing sample;
C. typical curve: prepare 1 * 10
-4the standard solution of mol/L sodium nitrite; In being numbered 7 10mL volumetric flasks of No. 1-7, add SN working fluid, each 1mL of NC working fluid, add respectively 1 * 10
-4mol/L sodium nitrite standard solution 0mL, 0.1mL, 0.2mL, 0.4mL, 0.6mL, 0.8mL, 1.0 mL; With described constant volume liquid S constant volume, shake up, after standing 30-120 minute, measure absorbance; This serial solution is typical curve nitrite ion to be measured;
D. absorbance is measured: adopt spectrophotometer, 1cm cuvette, at wavelength 515-525nm place, measures the absorbance of the nitrite ion of described typical curve nitrite ion to be measured and testing sample; The concentration that the absorbance of described typical curve nitrite ion to be measured of take is ordinate, nitrite is that horizontal ordinate is drawn absorbance-content of nitrite typical curve;
E. from described typical curve, try to achieve the content of nitrite of testing sample: by described typical curve, can be accessed: the concentration of the sodium nitrite corresponding with ordinate absorbance is 1 * 10
-5in mol/L, meet lambert-Beer law, linear equation is: A=28047x+0.001, and linearly dependent coefficient R=0.9995, wherein A is absorbance, the concentration that x is sodium nitrite;
F. content of nitrite-shooting time relation curve: 0h after shooting respectively, 2h, 4h, 8h, 12h, 24h, 36h, 48h, 72h, 120h, 168h obtains shooting residue extract to be measured with pure water rinsing gun inwall, it at wavelength, is the absorbance of the shooting residue extract to be measured of the gun that after 515-525nm place measures shooting, different time is corresponding, from described typical curve, try to achieve the nitrite concentration that each absorbance is corresponding, different time after drafting shooting and the relation curve of the shooting residue extract nitrite to be measured of corresponding gun, this is content of nitrite-shooting time relation curve, the absorbance of the extract of the shooting residue of mensuration suspicion gun, can determine content of nitrite and corresponding shooting time,
(5) determination of recovery rates: in 100mL volumetric flask, add respectively sodium nitrite standard solution, glacial acetic acid and developer, making content of nitrite is 1 * 10
-6mol/L, 2 * 10
-6mol/L, 4 * 10
-6mol/L; Recording respectively absorbance is: 0.0285,0.0582,0.1152; From described typical curve, trying to achieve corresponding content of sodium nitrite is respectively: 9.89 * 10
-7mol/L, 2.04 * 10
-6mol/L, 4.07 * 10
-6mol/L; Obtain the recovery that the assay method of this gun shooting time measures shooting residue nitrite between 98%-102%, can meet that shooting time is measured and the requirement of scientific research.
2. the assay method of a kind of gun shooting time according to claim 1, is characterized in that: described maximum absorption wavelength 520 nm; The consumption 0.2mL of described glacial acetic acid; The consumption 5mL of described sulfanilic acid; The consumption 10mL of described alpha-naphthylamine; The 30 minutes stabilization time of described chromogenic reaction.
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| CN103438922B (en) * | 2013-07-22 | 2015-08-05 | 广州市刑事科学技术研究所 | A kind of analysis estimating method of domestic standard pistol shooting distance |
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