Methyl Centralite Research Articles

Forensic analysis of a single particle of partially burnt gunpowder by solid phase micro-extraction–gas chromatography-nitrogen phosphorus detector

Solid phase micro-extraction (SPME) was adopted to extract organic gun shot residues (OGSRs) from a single particle of partially burnt gunpowder. The partially burnt particle samples were collected from gun shot residue (GSR) deposited near the target areas. OGSRs, such as diphenylamine (DPA), methyl centralite (MC), ethyl centralite (EC), from only one single particle of partially burnt gunpowder were successfully extracted by SPME and analyzed by a gas chromatography coupled to a nitrogen phosphorus detector (GC-NPD). The results confirmed that the new extraction procedure is capable of extracting trace amount of MC and EC as signature molecules for the identification of GSR. The method represents a solvent-free extraction as a complementary analytical procedure for the forensic analysis of GSR-related evidences. The new extraction scheme with the capability of analyzing single particle of partially burnt gunpowder can also be applied to the identification of explosive residues, such as in post-blast investigations of improvised explosive devices.

Characterization of smokeless powders using nanoelectrospray ionization mass spectrometry (nESI-MS)

Smokeless powder is one of the most common types of explosives used in civilian ammunition and, hence, its detection and identification is of great forensic value. Based on comparison of physical properties, extraction yield in methanol, and the spectra obtained using nanoelectrospray ionization and multistage tandem mass spectrometry (MS/MS) in a quadrupole ion trap mass spectrometer, a method was developed to identify and differentiate unburned smokeless powders from different brands of ammunition. The mass spectrometry method was optimized for the simultaneous detection of the organic stabilizers commonly present in smokeless powders: methyl centralite, ethyl centralite, and diphenylamine. All but two of the powders were differentiated; however, the two that were not differentiated were produced by the same manufacturer. Gunshot residue from the cartridges was deposited on cotton cloth and collision-induced dissociation MS/MS was used to identify low levels of ethyl centralite in the residue, despite the presence of contaminants.

Desorption Electrospray Tandem MS (DESI‐MSMS) Analysis of Methyl Centralite and Ethyl Centralite as Gunshot Residues on Skin and Other Surfaces

A direct and sensitive method for the detection of methyl centralite (MC) and ethyl centralite (EC) as gunshot residues (GSRs) has been developed. This method uses desorption electrospray ionization (DESI)-tandem mass spectrometry and directly desorbs and detects analytes from surfaces without any sampling process. Typical transitions for MC and EC, m/z 241 to m/z 134 and m/z 269 to m/z 148, respectively, were used to improve the assay sensitivity. It has been shown that MC and EC can be detected on various surfaces, with detection limits of 5-70 pg/cm(2). Interferences, detection time after shooting and the number of times hands were washed after shooting were also evaluated. None of the materials interfered with the results and the detection window for organic GSRs was up to 12 h and hands could be washed at least six times. Further samples were analyzed to confirm the reliability of this method, and showed that it could discriminate shooters from nonshooters. This method should be of significance in forensic science, especially in analyzing GSRs, because of its simplicity, high throughput, and the direct detection of MC and EC on suspects' hands, clothes, and hair.

The Utilization of MS-MS Method in Detection of GSRs

Abstract This paper describes a novel method to detect gunshot residues (GSRs). The components contained in the double-based smokeless powder were separated by using a HPLC system with UV detection at 223 nm. The result indicated that there are mainly two kinds of organic ingredients in the double-base smokeless powder used. These two organics do not include nitrocellulose because it has no evidential value in the HPLC-UV trace of the smokeless powder sample. By matching retention times of these two compounds with that of the five standards occurring in smokeless powder, the compounds are tentatively identified as methyl centralite (MC) and nitroglycerin (NG). These two compounds were finally identified by using MS spectrum. This MS-MS method was developed to detect MC since MC is less commonly found in the environment than NG. In Chinese ammunition, MC is widely used as a stabilizer instead of EC. Sixteen samples were used to evaluate the reliability of the method. The mean (±SD) MC level in the eight samples is 520.1 ± 271.9 pg/µL and that in the blanks is 31.0 ± 20.8 pg/µL. The result (P = 0.0007) shows that there is a significant difference between the two serial data. Sampling hands over a 24 h period showed that GSR could be detected even after 8 h with a 75% decrease in the level of MC. The result of the washing test shows that it is still possible to apply the proposed method to detect GSRs on a shooter's hands even if their hands have been washed three times. Another test shows that if the shooters wear gloves while firing, MC on the gloves can be easily detected using the proposed method.

Detection of N,N′-diphenyl-N,N′-dimethylurea (methyl centralite) in gunshot residues using MS-MS method

Download options Please wait... Article information DOI https://doi.org/10.1039/A904917G Article type Paper Download Citation Analyst, 1999,124, 1563-1567 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Detection of N,N′-diphenyl-N,N′-dimethylurea (methyl centralite) in gunshot residues using MS-MS method Z. Wu, Y. Tong, J. Yu, X. Zhang, C. Pan, X. Deng, Y. Xu and Y. Wen, Analyst, 1999, 124, 1563 DOI: 10.1039/A904917G To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Zhuping Wu Yan Tong Jianyuan Yu Xinrong Zhang Changxin Pan Xinyuan Deng Yucai Xu Yuxiu Wen

The application of infrared microimaging for the determination of the distribution, penetration depth, and diffusion profile of methyl centralite and dibutyl phthalate deterrents in nitrocellulose monoperforated propellant

AbstractInfrared microspectroscopy was used to determine quantitatively and qualitatively methyl centralite (MC) and dibutyl phthalate (DBP) diffusion profiles in cross sections of nitro‐cellulose‐based monoperforated propellant grains. The absorbance values of the CO peak of DBP at 1717 cm −1 and the aromatic CC peak of MC at 1496 cm −1 were measured relative to the NO2 overtone peak of the nitrocellulose at 2555 cm−1 at 10 μm intervals from the outside edge inward (external profile) and the perforation edge inward (internal profile). Infrared microimaging was used to determine the distribution and penetration depth of the DBP and MC using the CO peak of DBP at 1717 cm−1 and the aromatic CC peak of MC at 1496 cm−1 as diagnostic of the two deterrents to obtain the contour and axonometric displays of the distribution. © 1993 John Wiley & Sons, Inc.

Methylcentralite concentration profiles in monoperforated extruded nitrocellulose and nitrocellulose/nitroglycerine propellant grains by Raman microspectroscopy

AbstractRaman microscopy was used to determine the methylcentralite (MC) concentration profiles diffused into single‐base (nitrocellulose) (NC) and double‐based (nitrocellulose/nitroglycerine) (NC/NG) small‐arms propellant grains. External and internal concentration profiles were determined by measuring the concentration of MC relative to the NC and NC/NG at 5‐μm intervals into the grain from the edge inward and the perforation edge outward. The external profile was constant with a diffusion and interaction mechanism, i.e., a level concentration of deterrent through the outer region of the grain followed by a gradual dropoff in concentration with distance into the grains, whereas the internal profile was found to be dependent on perforation size with either a diffusion and interaction mechanism profile or a gradual decrease in concentration profile.

N-Alkylations and O-Alkylations of Nitro-Substituted 1,3-Diphenylureas: Preparations of Propellant Stabilizer Derivatives

A procedure has been developed for the N- ethylation and methylation of 1,3-diphenylureas, ArNRCONHAr′ (R = H, Me or Et), through treatment with sodium hydride and iodoalkane in dimethylformamide. The reaction was general, provided that the aniline to be alkylated was substituted with no more than one nitro group. ArRNCONR′Ar′ derivatives prepared were: R = R′ = Et (and Me); Ar = phenyl, Ar′ = 2-nitrophenyl and 4- nitrophenyl ; Ar = 2-nitrophenyl, Ar′ = 2-nitrophenyl and 4-nitrophenyl; Ar = Ar′ = 4-nitrophenyl. Two mixed derivatives were also prepared: R = Et, R′ = Me, Ar = phenyl, Ar′ = 2-nitrophenyl and 4-nitrophenyl. O-Alkylated isourea products were obtained in the reactions of 1-(2,4- dinitrophenyl )-3-(2-nitrophenyl)urea and 1-(2,4-dinitrophenyl)-3-(4- nitrophenyl )urea. The use of potassium carbonate as the base led to apparently exclusive O- alkylation of 1,3-bis(2-nitrophenyl)urea although the reaction was not general. 1-(2,4-Dinitrophenyl)-1,3- diethyl-3-phenylurea was prepared by using silver oxide and obtained as a mixture with the isourea . Many of the compounds prepared are important nitro derivatives of the propellant stabilizers, ethyl and methyl centralite.

Raman microspectroscopic determination of the methyl centralite (N, N′‐dimethyl‐N, N′‐diphenylurea) concentration profile in a nitrocellulose extruded mono‐perforated small arms propellant

AbstractA Raman microspectroscopic method for the determination of the concentration profile of a deterrent (methyl centralite) diffused into an extruded single base mono‐perforated small arms propellant (nitrocellulose) is presented. Preliminary results indicate a level concentration part way into the propellant from the external surface with an abrupt drop‐off in concentration, whereas from the internal surface an exponential concentration profile is obtained. These results indicate the possibility of two different diffusion mechanisms operating from the external and internal surfaces.

An infrared microspectroscopy method for determining deterrent penetration in nitrocellulose‐based propellant grains

AbstractInfrared microscopy was used to determine di‐n‐butyl phthalate, dinitrotoluene, and methyl centralite diffusion profiles in cross sections of nitrocellulose‐based propellant grains. Absorbance of marker functional groups was determined at 25–50 µm intervals from the edge to the center of the sections. Comparison of IR and light microscopical data indicated that the optically visible boundary does not define the entire depth of deterrent penetration into propellant grains.