CN104833653A - Method for rapidly analyzing content of hexogen in mixed explosive - Google Patents

Abstract

The invention relates to a method for rapidly analyzing the content of hexogen in a mixed explosive, and belongs to the technical filed of explosive detection and near infrared spectroscopy quantitative analysis. The method comprises the following steps: collecting and preparing samples in a certain concentration range, adopting a chemical technology measurement concentration as a reference value, acquiring the spectra of all the samples, establishing various models through combination of different wavebands, different pretreatment technologies and a bias least squares technology, and determining an optimal model according to the ideal degree of a cross check root mean square error (RMSECV) and an RMSECV/dimension curve. The wavebands of the optimal model are 9195.1-7802.8cm<-1>, 7660-6842.4cm<-1> and 6159.7-5403.7cm<-1>, and a pretreatment mode is first order derivative + multiplicative scatter correction. The accuracy and the precision of the method are confirmed by assessing the models. The method can be used for rapidly analyzing the content of hexogen in a mixed explosive.

Description

The rapid analysis of hexogen content in a kind of composite explosives

Technical field

The present invention relates to the rapid analysis of hexogen content in a kind of composite explosives, belong to explosive detection, Near-Infrared Spectra for Quantitative Analysis technical field.

Background technology

Hexogen is synthesized by Henning in 1899 first as medicine, and nineteen twenty-two Von Herz finds that it is a valuable explosive, and starts to put into production the thirties.Nowadays, hexogen is a kind of application explosive very widely.For the analysis of hexogen in composite explosives, current conventional analysis adopts solvent elution method.The method carries out analysis to a sample needs two technician's compounding practices, 4 hours consuming time.

Sample spectra and content of sample component utilize mathematical method to associate by Near-Infrared Spectra for Quantitative Analysis technology, founding mathematical models, afterwards collected specimens spectrum, just directly can be obtained the content of sample component by model.Near-Infrared Spectra for Quantitative Analysis technology, because of its quick, harmless, environmental protection, is saved the advantages such as human cost, is applied widely in industries such as agricultural, petrochemical compleies.Along with popularizing of this technology, this technology is applied in explosive detection field gradually.

2012, by name the method for PCTFE content " in the near infrared ray PBX explosive " that the people such as Xi'an Inst. of Modern Chemistry Wen Xiaoyan declare patent discloses a kind of method adopting near-infrared spectrum technique to detect chlorotrifluoroethylene (PCTFE) in composite explosives.2010, Xi'an Inst. of Modern Chemistry Su Peng flew to disclose a kind of method detecting HMX content in composite explosives in the content of HMX " in the near-infrared diffuse reflectance spectrometry Fast Measurement composite explosives " paper waiting people to deliver.

Obviously, these methods can not be used as the express-analysis of hexogen content in composite explosives, therefore, realize the express-analysis to hexogen content in certain composite material, need to create a kind of new method.

Summary of the invention

The object of the invention is to use solvent, not environmentally to solve the solvent elution method that generally adopts, and the cycle is long, cost is high, and existing fast, lossless detection method also cannot meet the problem of the detection of RDX content in composite explosives, the rapid analysis of hexogen content in a kind of composite explosives.

The object of the invention is to be achieved through the following technical solutions.

A rapid analysis for hexogen content in composite explosives, comprises the following steps:

Step 1: prepare and collect a collection of sample containing different RDX content; When designing preparation batch sample concentration, the strong correlation between each concentration of component be avoided.

Step 2: collected specimens spectrum, each sample repeated acquisition twice and more than, under the spectrum of repeated acquisition is placed in the same coordinate system, observes and reject the very large spectrum of difference.

Step 3: adopt solvent elution method to measure the content of RDX in composite explosives, as reference value.

Step 4: at random sample is divided into modeling collection and forecast set.

Step 5: adopt the method for Selective absorber relatively strong district wave band and select all method choice wave bands having absorption bands, and use wave band and the preprocessing procedures selected to combinationally use modeling collection sample to set up various model by partial least square method (PLS), by the desired level determination optimization model of employing crosscheck root-mean-square error (RMSECV), RMSECV/ dimension curve.The wave band of optimization model is 9195.1 ~ 7802.8cm ^-1, 7660 ~ 6842.4cm ^-1, 6159.7 ~ 5403.7cm ^-1, Pretreated spectra mode is: first order derivative+multiplicative scatter correction (MSC).

Step 6: the accuracy of method, accuracy are assessed.Adopt the accuracy of prediction standard deviation (SEP), mean absolute deviation evaluation method.Adopt Residue prediction deviation (RPD) characterization model for the resolution characteristic of RDX variable concentrations in forecast set sample.By submodel consistance scoring model accuracy.T inspection is adopted to carry out judging whether the method for the application is compared with the method for chemical method, exist larger systematic error.By carrying out the measurement of 10 repetitions to a sample in forecast set and calculating its standard deviation, compare this method and the difference of chemical method in repeatability.

Step 7: gather unknown sample spectrum, each sample repeated acquisition twice and more than, under the spectrum of repeated acquisition is placed in the same coordinate system, observes and reject the very large spectrum of difference.Measure spectrum, measurement result gets the mean value of repeated measuring results, and this mean value is the content of RDX in composite explosives.

Step 8: according to the actual requirements, on existing model basis, by adding the sample spectra of other concentration range, the detectability of extendible method.

Beneficial effect

1, use method of the present invention to carry out hexogen in certain composite explosives, containing the alternative existing chemical analysis method of quantitative analysis, analysis result to be obtained fast, not use any solvent, environmental protection, human cost, material cost can be reduced.

2, near infrared spectroscopy is adopted to measure hexogen content in certain composite explosives, when design sample concentration, avoid the strong linear correlation of other concentration of component and hexogen content, contrasted by repeated acquisition three spectrum, judge and rejecting abnormalities spectrum, by gathering the near infrared spectrogram comprising RDX and other each pure component, choose RDX and absorb the wave band comparatively strong, the absorption of other component is more weak, choose all RDX and have the wave band of absorption to choose effective wave band, these can be sets up excellent model and lays the foundation.When Modling model, by the efficient combination of wave-number range, preprocessing procedures, chemometrics method, be extracted the effective spectral information be associated with concentration.Adopt the desired level determination optimization model of crosscheck root-mean-square error (RMSECV), RMSECV/ dimension curve.By the accuracy of prediction standard deviation (SEP), mean absolute deviation, submodel consistance, Residue prediction deviation (RPD) evaluation method.By the accuracy of the standard deviation evaluation method of duplicate measurements gained.Thus the accuracy of ensuring method and accuracy.

Embodiment

Below by embodiment, the application is described in further detail.

Embodiment 1

Specifically being implemented as follows of technical scheme.

One, prepare and collect the sample of RDX content in certain limit

Preparation and collection 159 totally batches, sample, wherein, collect 68 batches, sample on production line, and design also workmanship fraction range is 91 batches, the sample of 50.24% ~ 60.0%.When designing the distribution of these sample concentrations, should avoid occurring strong linear correlation between component, in order to avoid the linear information of mistake is loaded in linear model.

Two, collected specimens spectrum

Gather the spectrum of all 159 batch sample, resolution is 8cm ^-1, scanning times is 32 times.

Each sample repeated acquisition spectrum three times, often gather a sample, under three of its correspondence spectrum are placed in same coordinate system, observe three spectrum and whether have the very large situation of difference, if one of them spectrum and all the other two spectrum difference very large, illustrate that this spectrum is exceptional spectrum, should be rejected.

Three, solvent elution method is adopted to analyze component concentration

Utilize solvent to the difference of different component solubleness, adopt solvent elution method to measure the massfraction of RDX in all 159 batch sample, as reference value.

Four, sample spectra is divided into modeling collection and forecast set

To all 159 batch sample according to the sequence of RDX concentration, random selecting 63 samples are as modeling collection sample, and all the other 96 samples are as forecast set sample.

Five, Modling model

Choose modeling wave band, the method chosen is:

1, the near infrared spectrogram comprising RDX and other each pure component is gathered.

2, from the near infrared spectrogram that step 1 gathers, choosing RDX absorbs comparatively strong, and other component absorbs more weak wave band Modling model;

3, from the near infrared spectrogram that step 1 gathers, choosing all RDX has the wave band of absorption to carry out modeling.

By the wave-number range of above-mentioned steps 2,3 initial option be: 4009 ~ 4022cm ^-1, 4073 ~ 4115cm ^-1, 4282 ~ 4345cm ^-1, 4377 ~ 4427cm ^-1, 4478 ~ 4498cm ^-1, 4531 ~ 4719cm ^-1, 5403.7 ~ 6159.7cm ^-1, 6842.4 ~ 7660cm ^-1, 7802.8 ~ 8215cm ^-1, 8215 ~ 8304cm ^-1, 8304 ~ 9195.1cm ^-1.

Utilize 63 samples of modeling collection, use the subrange of the wave band chosen to be combined through partial least square method (PLS) with various preprocessing procedures the absorption intensity value under selected wavelength is associated with the concentration value of sample, set up various PLS model, adopt the desired level determination optimization model of crosscheck root-mean-square error (RMSECV), RMSECV/ dimension curve.RMSECV is less, and model is better.Desirable RMSECV/ dimension curve is the increase along with dimension, and RMSECV reduced before this gradually, after reaching minimum value, increases gradually again or maintain an equal level along with dimension.

The formula of RMSECV is:

$\mathrm{RMSECV}=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(x_i-y_i)}^2}{n}}$

In formula, x _ifor modeling collection sample size predicted value during model crosscheck, y _ifor chemical method records the reference value of modeling collection sample size, n is the number of modeling collection sample.

The parameter of optimum PLS model is that wave band is chosen for: 9195.1 ~ 7802.8cm ^-1, 7660 ~ 6842.4cm ^-1, 6159.7 ~ 5403.7cm ^-1, Pretreated spectra mode is: first order derivative+multiplicative scatter correction.

Six, the assessment of method

(1) accuracy

Adopt model to predict 96 forecast set samples, result is as shown in table 1.

Table 1 uses a model predicting the outcome to 96 forecast set samples

Sample sequence number	Chemical method measurement result	Model prediction result	Deviation
				1	50.38	51.2035	0.82
2	50.66	51.0505	0.39
				3	50.66	51.3334	0.67
4	51.11	50.6193	-0.49
				5	51.17	51.8008	0.63
6	51.33	51.179	-0.15
				7	51.42	52.0368	0.61
8	51.61	52.1527	0.54
				9	51.68	51.8598	0.18
10	51.80	52.2715	0.47
				11	52.64	53.3363	0.70
12	52.69	52.6722	-0.01
				13	52.69	53.2682	0.58
14	52.70	53.033	0.34
				15	52.76	52.8575	0.10
16	52.78	52.4335	-0.34
				17	52.89	52.664	-0.22
18	53.15	53.5811	0.44
				19	53.24	53.981	0.74
20	53.24	53.4218	0.19
				21	53.29	53.4605	0.17
22	53.44	53.3712	-0.07
				23	53.64	53.4334	-0.20
24	53.71	53.963	0.26
				25	53.76	54.1789	0.42
26	53.83	54.5562	0.73
				27	54.13	54.1993	0.07
28	54.16	53.7663	-0.39
				29	54.21	54.8293	0.62
30	54.44	55.4104	0.97

31	54.49	53.9464	-0.54
				32	54.51	53.9252	-0.58
33	54.52	54.2705	-0.25
				34	54.70	55.0109	0.31
35	54.76	54.606	-0.15
				36	54.78	54.926	0.14
37	54.80	54.9635	0.16
				38	54.81	54.876	0.07
39	54.82	55.3496	0.53
				40	54.82	55.2869	0.47
41	54.85	55.1441	0.30
				42	54.99	55.3825	0.39
43	55.08	55.2765	0.20
				44	55.10	55.1289	0.03
45	55.14	54.8135	-0.33
				46	55.21	55.0899	-0.12
47	55.21	55.3314	0.12
				48	55.28	54.9267	-0.35
49	55.34	55.8171	0.47
				50	55.46	55.2962	-0.17
51	55.54	55.608	0.07
				52	55.55	55.5684	0.01
53	55.56	54.7538	-0.81
				54	55.57	55.3046	-0.27
55	55.58	55.5344	-0.05
				56	55.62	54.8241	-0.79
57	55.68	55.6433	-0.03
				58	55.68	55.4798	-0.20
59	55.71	55.1472	-0.56
				60	55.71	55.5591	-0.15
61	55.75	55.6792	-0.07
				62	55.75	54.8882	-0.86
63	55.75	55.1374	-0.61
				64	55.78	54.9022	-0.88
65	55.79	55.3383	-0.45
				66	55.81	55.2303	-0.58
67	55.81	56.0195	0.21

68	55.87	54.8934	-0.98
				69	55.89	55.0712	-0.81
70	55.97	55.0422	-0.93
				71	56.04	55.933	-0.11
72	56.08	55.5021	-0.58
				73	56.13	55.5473	-0.59
74	56.14	56.5625	0.42
				75	56.26	56.588	0.33
76	56.30	55.5644	-0.74
				77	56.39	55.982	-0.41
78	56.61	55.806	-0.80
				79	56.61	56.6211	0.01
80	56.63	56.7759	0.15
				81	56.71	56.7312	0.02
82	56.73	55.8176	-0.91
				83	56.75	56.5079	-0.25
84	57.21	57.7582	0.54
				85	57.49	57.5867	0.09
86	57.62	56.8415	-0.77
				87	57.94	57.8654	-0.07
88	57.99	57.2397	-0.75
				89	58.02	57.9349	-0.08
90	58.02	57.9773	-0.04
				91	58.52	57.7144	-0.80
92	58.92	58.6699	-0.25
				93	59.12	58.3224	-0.80
94	59.72	58.8992	-0.82
				95	59.92	59.1108	-0.81
96	60.12	59.2959	-0.82

First the assessment of accuracy adopts the accuracy of prediction standard deviation (SEP), mean absolute deviation, submodel consistance evaluation method.Adopt Residue prediction deviation (RPD) characterization model for the resolution characteristic of RDX variable concentrations in sample.

The formula of SEP is:

$\mathrm{SEP}=\sqrt{\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{(a_i-b_i-\mathrm{Bias})}^2}{n-1}}$

Wherein, a _ifor model is to the predicted value of forecast set sample, b _ifor the reference value that forecast set sample chemical method records, n is the number of forecast set sample

Wherein, the formula of Bias value is:

$\mathrm{Bias}=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(a_i-b_i)}{n}=-0.08$

Thus,

SEP＝0.50

Mean absolute deviation formula is as follows:

The result of calculation of SEP is 0.50, and mean absolute deviation is 0.41, illustrates that model has good accuracy.

When submodel consistance refers to for changing the sample sets for modeling, model prediction capacity variation is little.That near-infrared model can an anticipation parameter of Measurement accuracy.

Adopt crossing prediction, freeze some samples as predicted sample at every turn, all the other samples are used for modeling, use crosscheck root-mean-square error (RMSECV) scoring model predictive ability, when sample freeze quantity change time, be used for the sample of modeling and sample size is inevitable also change, its result is as shown in table 2.

Crossing prediction result when the different sample of table 2 crossing prediction freezes

Crossing prediction sequence number	Sample freezes number	RMSECV
			1	2	0.369

2	4	0.349
			3	6	0.351
4	8	0.365

Visible, along with the change of modeling sample collection, the predictive ability change of model is little, and thus, the submodel consistance of method is better.

The formula of RPD is:

Wherein, b _ifor the concentration value that forecast set sample chemical method records, for the mean value of concentration value, n is sample size.

Thus,

Residue prediction deviation (RPD) is 4.2, is greater than 2.5, illustrates that model has good density resolution to the sample that sample concentration is 50.24% ~ 60.0%.

In order to whether further determination methods exists larger systematic error, t inspection is adopted to judge.

21 groups of results are chosen to the result form of forecast set from model, as shown in table 3:

Table 3 model records the contrast of reference value for the predicted value of sample and chemical method

Wherein, $\stackrel{\&OverBar;}{d}=\frac{\mathrm{\&Sigma;d}}{n},S_d=\sqrt{\frac{\mathrm{\&Sigma;}{d}^2-\frac{{\left(\mathrm{\&Sigma;d}\right)}^2}{n}}{n-1}}.$

1. set up test-hypothesis, determine inspection level

H0: two method divergences are not remarkable, P> α

H1: two method divergences are remarkable, P< α

Bilateral: α=0.05

2. compute statistics

$t=\frac{\stackrel{\&OverBar;}{d}}{S_d/\sqrt{n}}=--0.9888$

Wherein, n is total number of samples.

3. determine P value, make statistical inference

Table look-up, t is less than critical value t (0.05,20)=2.086, P>0.5, obviously, and P> α.By α=0.05 level, accept H0, no significant difference, two method no significant differences.Thus, method of the present invention with compared with chemical method, without conspicuousness system deviation.

(2) accuracy

By this method model to same sample carry out 10 times repeat measurement and calculate its standard deviation, compare this method and the difference of chemical method in repeatability.Result is as shown in table 4.

The measurement result of parallel 10 times of RDX content in certain sample of table 4

Measure number of times	Chemical method	Model prediction
			1	55.66	55.35
2	55.59	55.35
			3	55.43	55.24
4	55.45	55.46
			5	55.65	55.37
6	55.44	55.40
			7	55.58	55.28
8	55.47	55.36
			9	55.62	55.38
10	55.63	55.29
			Standard deviation	0.0935	0.0637

As can be seen from standard deviation, repeatability, the accuracy of this method are suitable with chemical method.By assessment, model has good accuracy and accuracy.

Seven, unknown sample is measured

Gather unknown sample spectrum, repeated acquisition three times, under the spectrum of three repeated acquisition is placed in the same coordinate system, observe and rejecting abnormalities spectrum, measure spectrum, measurement result gets the mean value of duplicate measurements.This mean value is the content of RDX in composite explosives.

Use this method as shown in table 5 to 30 sample tests results of collecting in addition.

Table 5 this method predicts the outcome to 30 samples collected in addition

Sample sequence number

Reference value %

This method predicted value %

Deviation %

1	51.21	51.19	-0.02
				2	51.5	52.02	0.52
3	52.33	53.02	0.69
				4	53.26	53.58	0.32
5	53.32	53.23	-0.09
				6	53.74	53.93	0.19
7	53.76	54.43	0.67
				8	54.72	54.56	-0.16
9	54.68	54.82	0.14
				10	54.54	54.78	0.24
11	54.53	54.77	0.24
				12	54.87	55.43	0.56
13	55.31	55.32	0.01
				14	55.13	55.01	-0.12
15	55.13	54.78	-0.35
				16	55.54	55.36	-0.18
17	55.43	55.21	-0.22
				18	55.78	54.96	-0.82
19	55.98	55.54	-0.44
				20	55.53	54.65	-0.88
21	56.11	55.53	-0.58
				22	56.23	56.61	0.38
23	56.21	55.48	-0.73
				24	57.13	57.01	-0.12
25	58.03	57.92	-0.11
				26	58.01	57.95	-0.06
27	58.99	58.66	-0.33
				28	59.13	58.31	-0.82
29	59.62	58.8	-0.82
				30	60.21	59.53	-0.68

Eight, the expansion of model

When the scope of required detection is when 50.24% ~ 60.0% concentration range is outer, by increasing the spectrum of other range of concentrations sample, can the detectability of extended method.

Concrete steps are:

1, the sample of collection and other concentration range of preparation.Points for attention are with reference to embodiment step one.

2, embodiment step 2 is repeated to step 7.

Claims (2)

1. the rapid analysis of hexogen content in composite explosives, is characterized in that: comprise the following steps:

Step 1: prepare and collect a collection of sample containing different RDX content; When preparing batch sample concentration, the strong correlation between each concentration of component be avoided;

Step 2: collected specimens spectrum, each sample repeated acquisition twice and more than, under the spectrum of repeated acquisition is placed in the same coordinate system, observes and reject the very large spectrum of difference;

Step 3: adopt solvent elution method to measure the content of RDX in composite explosives, as reference value;

Step 4: at random sample is divided into modeling collection and forecast set;

Step 5: adopt the method for Selective absorber relatively strong district wave band and select all method choice wave bands having absorption bands, and use wave band and the preprocessing procedures selected to combinationally use modeling collection sample to set up various model by partial least square method (PLS), by the desired level determination optimization model of employing crosscheck root-mean-square error (RMSECV), RMSECV/ dimension curve; The wave band of optimization model is 9195.1 ~ 7802.8cm ^-1, 7660 ~ 6842.4cm ^-1, 6159.7 ~ 5403.7cm ^-1, Pretreated spectra mode is: first order derivative+multiplicative scatter correction (MSC);

Step 6: the accuracy of method, accuracy are assessed; Adopt the accuracy of prediction standard deviation (SEP), mean absolute deviation evaluation method; Adopt Residue prediction deviation (RPD) characterization model for the resolution characteristic of RDX variable concentrations in forecast set sample; By submodel consistance scoring model accuracy; T inspection is adopted to carry out judging whether the method for the application is compared with the method for chemical method, exist larger systematic error; By carrying out the measurement of 10 repetitions to a sample in forecast set and calculating its standard deviation, compare this method and the difference of chemical method in repeatability;

Step 7: gather unknown sample spectrum, each sample repeated acquisition twice and more than, under the spectrum of repeated acquisition is placed in the same coordinate system, observes and reject the very large spectrum of difference; Measure spectrum, measurement result gets the mean value of repeated measuring results, and this mean value is the content of RDX in composite explosives.

2. the rapid analysis of hexogen content in a kind of composite explosives as claimed in claim 1, it is characterized in that: after described step 7, according to the actual requirements, on existing model basis, by adding the sample spectra of other concentration range, the detectability of extendible method; Concrete steps are: collect the sample with other concentration range of preparation; Points for attention are with reference to embodiment step one; Repeat embodiment step 2 to step 7.