A method for distinguishing the source of black powder by sulfur isotope ratio and its application

Abstract

The present invention relates to the technical field of isotope geochemistry and physical and chemical analysis of explosives, and specifically to a method for distinguishing the source of black powder by sulfur isotope ratio and its application. The sulfur isotopes of black powder are analyzed by IRMS method, and the source of black powder is determined by the difference of sulfur isotope ratio. According to statistical analysis, the sulfur isotope values ​​are different, that is, P < 0.05, indicating that the raw materials are not homologous; combined with the results of trace element analysis, it is determined whether the raw materials of black powder are from the same source. The method of the present invention has high accuracy and effectively solves the judgment errors caused by the same or similar physical and chemical components in the prior art, as well as the false confusion and inaccuracy of the judgment results caused by the different raw material ratios.

Description

Technical Field

[0001] The invention relates to the technical field of isotope geochemistry and physical and chemical analysis of explosives, and in particular to a method for distinguishing the source of black powder by sulfur isotope ratio and an application thereof in source tracing. Background Art

[0002] Black powder is a mixture of potassium nitrate (about 75%), charcoal (about 15%) and sulfur (about 10%). Potassium nitrate is the oxidant in the explosion reaction, charcoal is used as fuel, and sulfur can reduce the ignition temperature and is used as fuel and adhesive. Explosives produced by raw materials from different regions or different processing techniques also have different stable isotope ratios, so they can be distinguished through isotope chemical element analysis.

[0003] At present, there have been studies on the differentiation and traceability of explosives at home and abroad. Generally, organic explosives, ammonium nitrate, black powder, etc. are distinguished through stable isotope analysis, and the stable isotope analysis of black powder usually includes three elements: nitrogen, carbon, and oxygen. For example, the document "Progress in Research on Stable Isotope Ratio Analysis Methods of Common Explosives" (published by Hu Can, Mei Hongcheng, etc. in 2021) clearly stated that "because sulfur isotopes are easy to remain and difficult to remove during the analysis process, general laboratories rarely carry out related tests", but there is a large overlap in the isotope ratio ranges of samples from different sources, and it is difficult to achieve traceability analysis of samples based solely on isotope information. In addition, existing studies have also found that temperature and humidity will affect the isotope ratio of nitrogen, so this poses a greater challenge to the traceability analysis of black powder.

[0004] Although the Chinese patent with publication number CN108314595A also discloses a radioactive microsphere detector for explosives marking and its preparation method, it uses isotopes 14 C is taken as the analysis object, and then identified and traced. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention proposes a method for distinguishing the source of black powder by using sulfur isotope ratio and application thereof.

[0006] This is achieved specifically through the following technical solutions:

[0007] A method for distinguishing the source of black powder by using sulfur isotope ratio, wherein the sulfur isotopes of multiple independent black powder samples are measured by IRMS method, and after statistical analysis, when the difference value P is less than 0.05, it indicates that the sulfur isotope values ​​of the samples are significantly different, indicating that the raw materials of the black powder are not homologous, and when the difference value P is greater than or equal to 0.05, it indicates that the sulfur isotope values ​​of the multiple black powder samples are not significantly different, and the raw material sources of the multiple black powder samples cannot be distinguished.

[0008] The sulfur isotope is δ 34S.

[0009] The analysis conditions of the IRMS are as follows: He flow rate: 20 ml / min; O2 flow rate: 5 ml / min; oxidation tube temperature: 800°C; reduction tube temperature: 620°C; chromatographic column temperature: 60°C.

[0010] A method for distinguishing the origin of black powder by using sulfur isotope ratio is used in black powder tracing.

[0011] Furthermore, a method for distinguishing the source of black powder using sulfur isotope ratio is used in black powder traceability, the steps comprising: first using ICP-MS to determine the trace element content in the black powder sample, and then using IRMS to determine the sulfur isotope ratio of the black powder sample, to obtain the trace element content and sulfur isotope ratio of multiple independent black powder samples, and to determine whether the black powders are of the same source by statistically analyzing the differences in sulfur isotope ratios and trace element contents. When the difference value between the trace element content and the sulfur isotope ratio is P<0.05, it indicates that the raw materials of the multiple independent black powder samples are not of the same source. Otherwise, that is, when the difference value is P≥0.05, it indicates that the sources of the raw materials of the multiple independent black powder samples cannot be distinguished.

[0012] The trace elements are Ca, Mn, Ga, Sr, Ba, Eu, Tm, Yb, Lu and U.

[0013] The analysis conditions of the ICP-MS are as follows: radio frequency power: 1325 W, plasma flow rate: 16 L / min, nebulizer flow rate: 0.9 L / min, auxiliary flow rate: 1.5 L / min, and data acquisition mode: peak-hopping acquisition.

[0014] The IRMS method is to grind the black powder to be tested into powder, pass it through a 60-mesh sieve, and then directly place it in an isotope ratio mass spectrometer for analysis.

[0015] The ICP-MS method is to pre-digest the mechanical energy of the black powder to be tested with nitric acid, then fully digest it with hydrogen peroxide, cool it to room temperature, add Re solution as an internal standard, fix the volume, absorb it, and then place it in an inductively coupled plasma mass spectrometer for analysis.

[0016] Furthermore, a method for distinguishing the source of black powder by sulfur isotope ratio is used in black powder source tracing, and the application method comprises the following steps:

[0017] Step 1 Trace element analysis

[0018] 1.1 Place the black powder sample in a digestion tank, add nitric acid, pre-digest at 100°C for 2 hours, then add hydrogen peroxide, place in a microwave digester and continue digestion for 2 hours. After the digestion is completed, cool to room temperature, add Re solution as an internal standard, make up to volume with ultrapure water, and dilute to obtain the digestion solution of the sample to be tested;

[0019] 1.2 The 10 trace elements Ca, Mn, Ga, Sr, Ba, Eu, Tm, Yb, Lu and U in the digestion solution of black powder were determined by ICP-MS and processed by SPSS 23.0 software;

[0020] 1.3 Using PCA cluster analysis and non-parametric detection method, the trace elements with small differences in content were classified into one category;

[0021] Step 2 Sulfur isotope analysis

[0022] 2.1 Take the black powder to be tested, grind it into powder, pass it through a 60-mesh sieve, and seal it for later use;

[0023] 2.2 Determination of the content of black powder in the test sample by IR-MS 34 S isotope ratio (calculated as δ 34 S value), and the data were processed using nonparametric test methods;

[0024] 2.3 According to the PCA cluster analysis results and δ 34 The difference in S value determines whether the source of the black powder to be tested is the same, where PCA is divided into one category and δ 34 For samples with non-significant differences in S values, the conclusion is that they have the same source; in other cases, the conclusion is that they have different sources.

[0025] The significant difference refers to P < 0.05 after statistical analysis.

[0026] Beneficial effects:

[0027] The method of the present invention has high accuracy. By analyzing the trace elements and sulfur isotopes of black powder, the trace elements and sulfur isotope characteristics of different samples are analyzed, and then the samples from different sources are distinguished. This effectively solves the problems in the prior art where the sources of samples with the same or similar physical and chemical components cannot be judged, and the judgment results are falsely confused and inaccurate due to the influence of different raw material ratios, which may lead to false confusion and inaccuracy.

[0028] The present invention utilizes the high resolution of isotope analysis to distinguish samples from different sources. Trace element analysis is first used to achieve rough classification, and the ICP-MS method has the characteristic of being able to measure the contents of multiple elements at one time, which reduces the sample processing cost. Isotope analysis is then used to achieve accurate judgment, thereby improving the accuracy of traceability information.

[0029] The present invention utilizes the difference characteristics of trace elements and sulfur isotope ratios of samples from different sources to distinguish samples of unknown origin and establish connections between different samples.

[0030] The present invention screened 40 elements in black powder samples and finally selected 10 trace elements, Ca, Mn, Ga, Sr, Ba, Eu, Tm, Yb, Lu and U, as judgment indicators. The reliability of the tracing results was increased by utilizing the fact that these 10 elements have significant differences with regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 : Cluster distribution diagram of δ34S values ​​of 25 samples in Example 1. DETAILED DESCRIPTION

[0032] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments, and any improvement or substitution based on the basic spirit of the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0033] Example 1

[0034] This example distinguishes the sources of 25 collected black powder samples, and the operation is as follows:

[0035] Part 1 Sample and Instrument Information

[0036] 1. Sample information

[0037] The 25 samples came from Guangdong (2), Zhejiang (11), Guizhou (6), Henan (1), Jiangsu (4) and Chongqing (1);

[0038] 2. Instruments and Reagents

[0039] Mat253 isotope ratio mass spectrometer, Flash EA 1112 elemental analyzer, X2 inductively coupled plasma mass spectrometer (ICP-MS) ICP-MS, Thermo Corporation, USA; electric blast drying oven, Shanghai Yiheng Scientific Instrument Co., Ltd.; sulfur isotope standard: GBW04414 standard (P-GBW04414, silver sulfide) for external standard calibration, purchased from Beijing Ruili Junli Development Co., Ltd.

[0040] Diabase powder standard material (W-2a) and Hawaiian volcanic basalt standard (BHVO-2) were selected as standard materials, including 40 elements: Li, Be, B, K, Ca, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, Pb, Th and U, with a concentration of 1ng / mL-2000ng / mL;

[0041] Part II Sample Processing

[0042] IR-MS: weigh about 200 μg of sample, grind into powder, pass through a 60-mesh sieve, and seal for later use; the test instrument is MAT-253, Vienna Canyon Diablo Troilite (V-CDT) is used as the reference standard, STD-1 (-0.22‰), STD-2 (22.57‰) and STD-3 (-32.53‰) are used as standard samples for data correction, and the test error is ±0.1‰ (2σ);

[0043] ICP-MS: Weigh 200 mg of sample, transfer to a digestion tank, add 3 mL of 65% nitric acid, pre-digest at 100°C for 2 hours, add 1 mL of 30% hydrogen peroxide, place in a microwave digester, and continue digestion for 2 hours. After digestion, cool to room temperature, add 0.5 mL of 10 mg / mL Re solution as an internal standard, and then dilute to 10 mL with ultrapure water. Dilute 10 times with ultrapure water before ICP-MS analysis;

[0044] Part III Testing Conditions and Methods

[0045] 1. Test conditions

[0046] IR-MS: He flow rate: 20 ml / min; O2 flow rate: 5 ml / min; Oxidation tube temperature: 800°C; Reduction tube temperature: 620°C; Chromatographic column temperature: 60°C;

[0047] ICP-MS: RF power: 1325W; plasma flow: 16L / min; nebulizer flow: 0.9L / min; auxiliary flow: 1.5L / min; data acquisition method: peak-jumping acquisition;

[0048] 2. Methods

[0049] 1) Trace element analysis

[0050] Take the digestion solution of the black powder sample to be tested and put it into the ICP-MS instrument to determine the 10 trace elements Ca, Mn, Ga, Sr, Ba, Eu, Tm, Yb, Lu and U in each sample, and keep records;

[0051] 2) PCA cluster analysis

[0052] Principal component analysis was performed using data dimensionality reduction to classify the 25 samples;

[0053] 3) 34 S isotope analysis

[0054] Take the black powder sample powder and place it in the IR-MS instrument to determine the content of the black powder sample. 34 S isotope ratio δ 34 S;

[0055] 3. Data processing and judgment criteria

[0056] Data analysis SPSS 23.0 (IBM, USA) was used for statistical analysis. Nonparametric tests were used to analyze the trace elements and δ 34 The S value was analyzed for differences. When P < 0.05, it means that the element data of multiple samples are significantly different, and the raw materials of the multiple samples to be tested come from different sources. When P ≥ 0.05, it means that the element data of multiple samples are not significantly different, and the raw materials of the multiple samples to be tested come from the same source.

[0057] Part IV Results and Discussion

[0058] 1. Trace element analysis

[0059] Non-parametric tests were performed on 40 elements in 25 black powder samples. The results showed that 10 elements, including Ca, Mn, Ga, Sr, Ba, Eu, Tm, Yb, Lu and U, in the samples differed significantly among regions. The sample data are shown in Table 1.

[0060] Table 1 Contents of 10 characteristic trace elements in samples from different regions (μg / kg)

[0061]

[0062]

[0063] Note: “-” means not detected.

[0064] According to the results of elemental analysis, although some samples were seized from the same province, the results of trace element determination were very different. After the samples were divided into two groups according to the element content, the results of non-parametric tests showed that there was a significant difference between the two groups of samples. Therefore, the 11 samples from Zhejiang were divided into two categories, including 8 in category I and 3 in category II, which were respectively represented by Zhejiang-I and Zhejiang-II; similarly, the 6 samples from Guizhou were divided into three categories, including 2 in category I, 2 in category II, and 2 in category III, which were respectively represented by Guizhou-I, Guizhou-II, and Guizhou-III.

[0065] Compared with Zhejiang Class I samples, the 10 elements in Zhejiang Class II samples are all higher; among the three types of samples from Guizhou, Guizhou III contains the highest concentration of Ca, and the other elements are the highest in Guizhou Class II samples. Compared with Guizhou Class I samples, Guizhou Class III samples have higher Mn and Sr, while Ga, Ba, and U contents are lower, and the contents of other elements are comparable.

[0066] 2. Sulfur isotope analysis

[0067] The isotope analysis results of the 25 samples are shown in Table 2. 34 The S value is between -4.11‰ and 16.80‰.

[0068] Table 2 δ34S isotope ratios of samples from different regions

[0069]

[0070] PCA classification is performed on 25 samples, and the results are as follows Figure 1 As shown;

[0071] δ of two samples from Guangdong 34 The S values ​​were 13.66‰ and 14.84‰, respectively, which were not much different. It was inferred that the potassium nitrate in the two samples came from the same source. The sulfur isotope analysis results of the eight samples from Zhejiang I were also quite different from the elemental analysis results. 34 S value, the 11 samples were divided into three groups: Sample No. 3 was one group of δ 34 The S value is -3.72‰; samples 11-13 are a group, δ 34 The S value is -3.88‰—-4.11‰; samples 4-10 are a group, δ 34 The S value is 2.70‰-5.66‰, indicating that the sulfur in the 11 samples may have three different sources.

[0072] The sulfur isotope analysis results of 6 samples from Guizhou were similar to the element results, and the 6 samples were completely distinguished; 1 sample from Henan and 1 sample from Chongqing were significantly different from samples from other regions both in terms of elements and sulfur isotopes.

[0073] The four samples from Jiangsu were relatively concentrated and were divided into one category, δ 34 The S value is 5.25‰-6.25‰.

[0074] Combining the results of elemental analysis and sulfur isotope analysis, samples from different regions were distinguished. The results showed that: the two samples from Guangdong had the same source; the 11 samples from Zhejiang had three different sources, which, combined with the characteristic trace element information, could be attributed to the same source; the six samples from Guizhou had the same source; the four samples from Jiangsu had the same source; and the one sample from Henan and Chongqing had a different source from samples from other places.

Claims

1. Application of a method for distinguishing the source of black powder by sulfur isotope ratio in black powder source tracing, characterized in that: The application comprises the following steps: firstly, using the ICP-MS method to measure the characteristic trace element content in a plurality of black powder samples, then using the IRMS method to measure the sulfur isotope values ​​of the plurality of black powder samples, and then statistically analyzing the difference in the sulfur isotope ratio and the difference in the trace element content to determine whether the black powders are homologous, when the difference value P between the trace element content and the sulfur isotope ratio is less than 0.05, it indicates that the sample raw materials are not homologous, otherwise, that is, P≥0.05, it indicates that the sources of the sample raw materials cannot be distinguished; The analysis conditions of the IRMS are as follows: He flow rate: 20 ml / min; O2 flow rate: 5 ml / min; oxidation tube temperature: 800°C; reduction tube temperature: 620°C; chromatographic column temperature: 60°C.

2. Application of the method for distinguishing the source of black powder by sulfur isotope ratio as claimed in claim 1 in black powder source tracing, characterized in that: The sulfur isotope is δ 34 S.

3. Application of the method for distinguishing the source of black powder by sulfur isotope ratio as claimed in claim 1 in black powder source tracing, characterized in that: The IRMS method is to grind the black powder to be tested into powder, pass it through a 60-mesh sieve, and then directly place it in an isotope ratio mass spectrometer for analysis.

4. Application of the method for distinguishing the source of black powder by sulfur isotope ratio according to claim 1 in black powder source tracing, characterized in that: The characteristic trace elements are Ca, Mn, Ga, Sr, Ba, Eu, Tm, Yb, Lu and U.

5. Application of the method for distinguishing the source of black powder by sulfur isotope ratio as claimed in claim 1 in black powder source tracing, characterized in that: The analysis conditions of the ICP-MS are as follows: radio frequency power: 1325 W, plasma flow rate: 16 L / min, nebulizer flow rate: 0.9 L / min, auxiliary flow rate: 1.5 L / min, and data acquisition mode: peak-hopping acquisition.

6. Application of the method for distinguishing the source of black powder by sulfur isotope ratio according to claim 1 in black powder source tracing, characterized in that: The ICP-MS method is to first mechanically pre-digest the black powder sample with nitric acid, then fully digest it with hydrogen peroxide, cool it to room temperature, add Re solution as an internal standard, fix the volume, absorb it, and then place it in an inductively coupled plasma mass spectrometer for analysis.

7. Application of the method for distinguishing the source of black powder by sulfur isotope ratio as claimed in claim 1 in black powder source tracing, the application method comprising the following steps: Step 1 Trace element analysis 1.1 Place the black powder sample in a digestion tank, add nitric acid, pre-digest at 100°C for 2 hours, then add hydrogen peroxide, place in a microwave digester and continue digestion for 2 hours. After the digestion is completed, cool to room temperature, add Re solution as an internal standard, make up to volume with ultrapure water, and dilute to obtain the digestion solution of the sample to be tested; 1.2 The 10 characteristic trace elements Ca, Mn, Ga, Sr, Ba, Eu, Tm, Yb, Lu and U in the digestion solution of black powder were determined by ICP-MS and processed by SPSS 23.0 software; 1.3 Using PCA cluster analysis, the trace element contents with small differences were grouped into one category; Step 2 Sulfur isotope analysis 2.1 Take the black powder to be tested, grind it into powder, pass it through a 60-mesh sieve, and seal it for later use; 2.2 Determination of δ in black powder by IRMS 34 S isotope ratio (calculated as δ 34 S value), and the data were processed using SPSS23.0 software; 2.3 According to the PCA cluster analysis results and δ 34 The difference in S value determines whether the source of the black powder to be tested is the same, where PCA is divided into one category and δ 34 For samples with non-significant differences in S values, the conclusion is that the samples have the same source, and for other cases, the conclusion is that the samples have different sources. The significant difference was P < 0.05.

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