The analysis of unfired propellant particles by gas chromatography mass spectrometry a forensic approach

THE ANALYSIS OF UNFIRED PROPELLANT PARTICLES BY GAS CHROMATOGRAPHY – MASS SPECTROMETRY: A FORENSIC APPROACH A thesis presented to the Queensland University of Technology in fulfilment of the requirements for the degree of Masters of Applied Science (Research) by Shiona Croft Bachelor of Applied Science Under the Supervision of: Dr John Bartley School of Physical and Chemical Sciences Queensland University of Technology April 2008 $%675$&7 In Australia, the 0.22 calibre ammunition is the most encountered ammunition type found at a crime scene [1] Previous analysis of gun shot residue (GSR) and unfired propellant has involved studying the inorganic constituents by Scanning Electron Microscopy or similar technique However, due to the heavy metal build up that comes with some ammunition types, manufacturing companies are now making propellant that is safer to use Therefore, it has become appropriate to study and analyse unfired propellant by other means One such technique is unfired propellant analysis by gas chromatography – mass spectrometry (GC-MS) This technique focuses on the organic constituent make up of the propellant paying particular attention to diphenylamine, ethyl centralite and dibutyl phthalate It was proposed that different batches of ammunition could be discriminated or matched to each other by using this technique However, since the main constituents of unfired propellant are highly reactive, it was not possible to accomplish batch determination of ammunition However, by improving extraction techniques and by removing oxygen (a catalyst for the degradation of diphenylamine) a superior method was established to help in the analysis of unfired propellant Furthermore, it was shown that whilst differentiating batches of the same ammunition was not possible, the improved methods have helped identify different types of the same brand of ammunition With the aid of future studies to fully explore this avenue, the analysis of unfired propellant could one day become an integral part of forensic science The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft ii 67$7(0(17 2) 25,*,1$/ $87+256+,3 The work contained in this thesis has not been previously submitted to meet requirements for an award at this or any other higher education institution To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made Shiona Croft Date The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft iii $&.12:/('*(0(176 I wish to thank all those people who over the past years have seen me through my best and my worst… Firstly, to my supervisor Dr John Bartley (QUT) for your advise, patience and support throughout my research Your expert knowledge and direction was greatly appreciated In particular, your considerable experience with mass spectrometry and research methodologies Also, for your endless endurance, patience and guidance with regards to the thesis write up For all your help, I thank you To the Queensland Police Service (Mr Gary Asmussen and the members of the Analytical Services Unit) for allowing me to take up this research but for also giving me the freedom to explore this project in the direction I thought most appropriate Thank you To my colleague and friend Dr Helen Panayiotou, thank you for your words of wisdom Your encouragement and valuable direction when I felt lost was appreciated greatly To my mum and dad who has been supportive from day one Your support, enthusiasm and confidence in my abilities allowed me to have courage in my work Thank you for never allowing me to give up – although I am too stubborn to so! To my dear Chris, who everyday told me how proud of me he was Thank you for putting up with the late nights and the stress For your love, friendship and strength – I honestly could not have done this without you You mean everything to me To my brother Kevin, who I know is very proud of me Thanks for your support Kev! The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft iv To my Ouma and Grandad, Connie and Gerald Campbell, I wish you could be here but you are always in my thoughts Thank you for your support and interest in my thesis It means so much to me that even though you are far away your love and encouragement is not forgotten I miss you To my very much loved group of friends; Scott, Niki, Amy, Mick, Nikki and everyone else who has been there for me Some of you have been around for more than a decade and your love, encouragement and support is never forgotten You all mean the world to me and thank you for giving me the strength to go on Finally, to all the post graduate students whom I may not have seen as much as I would have liked (since being off campus) but to my friend Dr Sarah Ede in particular, who constantly inspired me and who I always knew would great things Thank you The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft v 7$%/( 2) &217(176 $%675$&7 II 67$7(0(17 2) 25,*,1$/ $87+256+,3 III $&.12:/('*(0(176 IV 7$%/( 2) &217(176 VI /,67 2) ),*85(67$%/(6 VIII $%%5(9,$7,216 XI  ,1752'8&7,21 1.1 BACKGROUND 1.2 THE 0.22 CALIBRE AMMUNITION 1.2.1 The Cartridge 1.2.2 The Projectile 1.2.3 The Propellant 1.2.4 The Primer 1.3 PREVIOUS WORK RELATED TO ORGANIC GUN SHOT RESIDUE OR UNFIRED PROPELLANT ANALYSIS  (;3(5,0(17$/ 18 2.1 MATERIALS 18 2.2 INSTRUMENTATION 18 2.3 STANDARD PREPARATION 19 2.4 ETHYL ACETATE ALONE PROCEDURE 19 2.5 ETHYL ACETATE/DICHLOROMETHANE PROCEDURE 19 2.6 CONSISTENCY OF PROPELLANT COMPOSITION EXPERIMENT 20 2.7 EXCLUSION OF OXYGEN EXPERIMENT 20 2.8 TYPE DETERMINATION OF WINCHESTER AMMUNITION 20  3.1 5(68/76 $1' ',6&866,21 22 MASS SPECTRA OF UNFIRED PROPELLANT COMPONENTS 22 The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft vi 3.1.1 Diphenylamine (C12H11N) 22 3.1.2 Ethyl centralite (C17H20N2O) 24 3.1.3 Dibutyl phthalate (C16H22O4) 26 3.2 CONTROLLED STANDARDS 28 3.2.1 Diphenylamine, ethyl centralite and dibutyl phthalate variation 29 3.3 THE ANALYSIS OF PROPELLANT USING ETHYL ACETATE ALONE 30 3.4 REMOVAL OF THE NITROCELLULOSE COMPONENT OF PROPELLANT USING ETHYL ACETATE AND DICHLOROMETHANE 44 3.5 CONSISTENCY OF PROPELLANT COMPOSITION FROM A SINGLE BOX/BATCH OF AMMUNITION 53 3.6 THE EFFECTS OF EXCLUDING OXYGEN 58 3.7 TYPE DETERMINATION OF WINCHESTER AMMUNITION 65 3.7.1 Winchester Laser LR HP 2DRM41 65 3.7.2 Winchester Expert 23DLH02 66 3.7.3 Winchester Winner IDKE52 66 3.7.4 Winchester Subsonic LR Rim fire AED1FH31 67 3.7.5 Winchester Superspeed LR HV solid SDSB51 68 3.7.6 Winchester Superspeed LR HV hollow point 2DRL62 69  &21&/86,216 $1' )8785( :25 72 4.1 CONCLUSIONS 72 4.2 FUTURE WORK 73 $33(1',; 74 Ethyl Centralite standard 74 Dibutyl phthalate standard 75 Diphenylamine standard 76 Winchester Laser Long Rifle Hollow point 2DRM41 77 Winchester Expert 23DLH02 78 Winchester Winner IDKE52 79 Winchester Subsonic Long rifle Rim fire AED1FH31 80 Winchester Superspeed Long Rifle High velocity solid 2DSB51 80 Winchester Superspeed long rifle high velocity hollow point 2DRL62 81 5()(5(1&(6 82 The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft vii /,67 2) ),*85(67$%/(6 Figure 1.1: Dissected view of the case [8] Table 1.1: Elution order for constituents using HPLC-MS[29] Figure 1.2 Degradation of DPA [10,11] Table 1.2: Results from Northrop[46,47] 15 Table 3.1: Selected target compounds (from NIST library) 22 Figure 3.1 Mass spectrum of diphenylamine 24 Figure 3.2 Chemical structure of diphenylamine and m/z = 77 fragment ion (C6H5) 24 Figure 3.3: Ethyl Centralite 25 Figure 3.4: Mass spectrum of ethyl centralite 25 Figure 3.5: Fragmentation ions of ethyl centralite 25 Figure 3.6: Fragment A = m/z 120 and Fragment B = m/z 148 26 Figure 3.7: General structure of phthalate esters where R, R’ = CnH2n+1; n=415[50] 26 Figure 3.8: Characteristic fragmentation ions of butyl phthalate esters [51] 27 Figure 3.9: Mass spectrum and chemical structure of dibutyl phthalate 28 Table 3.2 DPA, EC and DBPH standard variation 29 Table 3.3 Variation in peak area of DPA between three random propellant samples and variation observed between the three samples 31 Figure 3.10: Diphenylamine degradation over time 31 Figure 3.11: Sample - diphenylamine degradation 32 Figure 3.12: Sample - diphenylamine degradation 33 Figure 3.13: Sample - diphenylamine degradation 33 Figure 3.14: 2-nitro-diphenylamine amounts detected (three random samples) – Extrapolated to time zero to give appreciation of initial amounts of 2nitro-DPA in each sample 34 Figure 3.15: Mechanisms of N-Nitroso-DPA in the presence of NO2 and O2 [16] 36 Figure 3.16: Lussier and Gagnon [14]: Concentration of DPA and its derivatives as a function of added nitrogen dioxide 37 The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft viii Figure 3.17: Effect of storage on diphenylamine concentration (sample one and two) 38 Figure 3.18: Sample - Effect of storage on diphenylamine (triplicate) 39 Figure 3.19: Sample - The effect of storage on 2- nitro-diphenylamine (analysed three times) 40 Figure 3.20: Sample one and two analysed each three times (average): comparison between stored samples and samples left in solution for one week 41 Figure 3.21: The effect of leaving propellant in solution over one week (2-nitro-DPA average – each sample analysed three times) 42 Figure 3.22: Diphenylamine response (EtAc/Ch2Cl2 procedure) 45 Figure 3.23: Comparison between EtAc alone and EtAc/CH2Cl2 on DPA (average) 46 Figure 3.24: Comparison of EtAc alone and EtAc/CH2Cl2 procedures - 2-nitro-dpa (average: each sample analysed three times) 47 Figure 3.25: 2-nitro-dpa levels - sample 1: comparison between EtAc alone and EtAc/CH2Cl2 procedures 48 Figure 3.26: Comparison between EtAc alone and EtAc/CH2Cl2 procedures (ethyl centralite average) 50 Figure 3.27: Dibutyl phthalate – comparison between EtAc alone and EtAc/CH2Cl2 procedures 51 Table 3.4: Relationship between sample size and population size 53 Table 3.5: Masses from ten random samples from one box of ammunition 53 Figure 3.28: Levels of diphenylamine of ten (10) random samples of propellant from the one box of ammunition 55 Figure 3.29: Levels of dibutyl phthalate detected of ten (10) random samples of propellant from the one box of ammunition 55 Table 3.6: Ratios (peak area) of main constituents from one box of ammunition 56 Figure 3.30 Inert gas procedure consequences on the main constituents of unfired propellant particles 58 Figure 3.31: Inert gas procedure (dibutyl phthalate) 60 Figure 3.32: The effects of leaving propellant in solution under an inert atmosphere 61 The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft ix Figures 3.33: Re-analysis of samples A-D 24 hours later (individually separated for visual clarity) 63 Figure 3.34: Winchester Laser LR HP 2DRM41 65 Figure 3.35: Winchester Expert 23DLH02 66 Figure 3.36: Winchester Winner IDKE52 67 Figure 3.37: Winchester Subsonic LR Rim fire AED1FH31 68 Figure 3.38: Winchester Superspeed LR HV solid 2DSB51 69 Figure 3.39: Winchester Superspeed LR HV hollow point 2DRL62 70 Table 3.7: Type determination of Winchester ammunition 71 The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft x Table 3.7: Type determination of Winchester ammunition TYPE DETERMINATION OF WINCHESTER AMMUNITION 2,4 DNT DEPH DPA EC DBPH 2-nitro-DPA LASER 113537 12090531 399766 5839487 69363 LASER 25910 12367704 452139 6050093 77941 EXPERT 62202 14066 13018543 472540 7817919 109952 EXPERT 29428 24596 11199852 381547 6645549 66117 WINNER 67272 34122 12412663 411209 8228937 72620 WINNER SUBSONIC SUBSONIC 0 750668 34599 654262 0 526481 38872 277880 0 523411 31802 246360 SOLID 0 722919 35690 808693 SOLID 0 641360 42846 894639 SUPER 0 906741 46743 401057 SUPER 0 1044449 55838 520898 It is not recommended to discriminate these types of ammunitions based on the quantity of each constituent as it varies between rounds of ammunition Discrimination could be performed on the basis of constituents in each type of ammunition For example, Expert type ammunition could be discriminated from Laser type ammunitions based on the presence of DNT It may be possible to distinguish between ammunition based on the concentrations of DPA, EC and DBPH In a crime scene scenario, it would be recommended to analyse more than two controls to gain a better measure of the variation found within that box of ammunition In that way, an average or range of DPA, EC and DBPH concentrations could be obtained for that particular box of ammunition and the recovered propellant sample could then be compared to the average or range The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 71  &RQFOXVLRQV DQG )XWXUH :RUN  &RQFOXVLRQV The possibility of discriminating batches of ammunition based on their organic composition has been deemed to be difficult The chemical nature of some of the compounds present in the propellant means that they are reactive compounds Therefore, to match propellant samples back to a known source is impossible For example, it has been mentioned that diphenylamine is a propellant stabilizer and is present to react with free nitrogen oxides to prevent auto ignition of the propellant As a consequence, diphenylamine is a reactive compound and is not a suitable analyte to use for batch discrimination The compound ethyl centralite is quite similar in chemical function and therefore is also reactive and unstable The only stable organic compounds present in propellant are the phthalates or plasticizers It could be argued that ammunition from different sources could be differentiated based on the concentration of the phthalates present, even on the different types of phthalates present However, the variations within the same batch of ammunition would need to be further explored Conversely, it may be argued that due to the abundance of phthalates in our everyday lives, discriminating ammunition using this common compound may not be valid Furthermore, the exact chemical make up of propellant and smokeless powders remains unclear [45] My own observations of the manufacturing process support this claim Throughout the project, the effects of oxygen are apparent Removing oxygen from the samples did play a significant role in preserving the representative chemical make up of the propellant Furthermore, extracting the nitrocellulose component from the propellant extract did benefit the project in that it removed the source of further nitration and reactions However, it was shown that the homogeneity of the propellant could not be established as varying concentrations of propellant are placed The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 72 randomly in each cartridge case Manufacturing companies are interested in barrel pressure of the ammunition, not the mass of the charge Even though the possibility of batch determination could not be carried out, new extraction techniques and improved methodologies have been established that could benefit the study of unfired propellants and organic gun shot residue Furthermore it is suggested that brand determination of the ammunition may be a possibility  )XWXUH :RUN Future studies should be carried out, however, the focus of these studies should be on brand and types of ammunitions as opposed to batches It was shown that different types of ammunition have different chemical compositions and therefore could be discriminated based on this characteristic A more comprehensive study of different Winchester ammunition types could reveal chemical differences and therefore could be useful to law enforcing agencies Furthermore, studies of different brands of ammunition could also reveal diverse chemical compositions A database could be created to indicate whether a propellant sample recovered from a crime scene, could be similar in chemical composition to different brands of ammunition found in Australia and overseas Another study which could explore the possibility of handling the propellant under nitrogen includes opening a cartridge case under nitrogen and collecting the propellant sample Half of the sample could be stored under nitrogen for a set period of time whilst the other is subjected to open air for the same period of time The subsequent extraction and analysis of the two separated propellant samples could provide a direct comparison between the storage and manipulation methods Whilst batch matching may not be a possibility, unfired propellant analysis may be able to give the police useful information into the likely sources of the recovered propellant sample Therefore this type of analysis could play an integral role in the field of forensic science The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 73 $33(1',; Ethyl Centralite standard The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 74 Dibutyl phthalate standard The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 75 Diphenylamine standard The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 76 Winchester Laser Long Rifle Hollow point 2DRM41 (A – Diethylphthalate; B – Diphenylamine; C –N, N diphenylformamide; D – Ethyl Centralite; E – Dibutyl phthalate; F: 2-nitro-diphenylamine) The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 77 Winchester Expert 23DLH02 (A – 2,4 Dinitrotoluene; B – Diethylphthalate; C – Diphenylamine; D – N,Ndiphenylformamide; E – Ethyl centralite; F – Dibutyl phthalate; G – 2-nitro diphenylamine) The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 78 Winchester Winner IDKE52 (A – 2,4 Dinitrotoluene; B – Diethylphthalate; C – Diphenylamine; D – N,N Diphenylformamide; E – Ethyl Centralite; F – Dibutyl phthalate; G – 2-nitro diphenylamine) The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 79 Winchester Subsonic Long rifle Rim fire AED1FH31 (A – Diphenylamine; B – Ethyl centralite; C – Dibutyl phthalate) Winchester Superspeed Long Rifle High velocity solid 2DSB51 (A –Diphenylamine; B – Ethyl Centralite; C – Dibutyl phthalate) The Analysis of Unfired 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Journal of Forensic Sciences 48 (3), 1-16 Kurnar, R (1999) A mass spectral guide for quick identification of phthalate esters In American Laboratory (Vol 33-35) McLafferty, F.W (1980) Interpretations of mass spectra: 3rd Edition, Cornell University MacChrehan, E.D., D; Reardon, M (2002) Associating gunpowder and residues from commercial ammunition using compositional analysis Journal of Forensic Sciences 47 (2), 260-266 MacChrehan, W.P., E; Duewer, D; Reardon, M (2001) Investigating the effect of changing ammunition on the composition of Organic additives in gunshot residue (OGSR) Journal of Forensic Sciences 46 (1), 57-62 The Analysis of Unfired Propellant Particles by Gas Chromatography-Mass Spectrometry: A Forensic Approach Shiona Croft 85 ... Particles by Gas Chromatography- Mass Spectrometry: A Forensic Approach Shiona Croft 20 The Analysis of Unfired Propellant Particles by Gas Chromatography- Mass Spectrometry: A Forensic Approach Shiona... alkyl, aryl groups or The Analysis of Unfired Propellant Particles by Gas Chromatography- Mass Spectrometry: A Forensic Approach Shiona Croft 22 organic radicals Amines, like ammonia, are weak bases... the way for further investigations into this area The Analysis of Unfired Propellant Particles by Gas Chromatography- Mass Spectrometry: A Forensic Approach Shiona Croft Wu et al[29] used a tandem