枪弹射击残留物检验方法

射击残留物作为涉枪案件的重要物证,是法庭科学领域的重要研究对象.射击残留物主要源于未燃烧或者部分燃烧的发射药、底火等,主要残留于射击者、枪支及被射客体上.随着各类分析检验方法的发展,针对射击残留物中的有机成分和无机成分,射击残留物的检验方法也从简单的化学检验发展到更加准确的仪器分析.     

Detection of organic gunshot residues from human hands using direct sample analysis-time of flight-mass spectrometry

The organic gunshot residues (OGSRs), specifically methyl centralite (MC; 1,3-dimethyl-1,3-diphenylurea), ethyl centralite (EC; 1,3-diethyl-1,3-diphenylurea), 2,4-DNT (2,4-dinitrotoluene), and TNT (trinitrotoluene), are characteristic compounds for which forensic analysts test determining if a person has discharged a firearm. A set of 200 samples from 50 shooters were collected as part of the validation study. Pistol 9 mm and special revolver .38 were fired at indoor and outdoor shooting ranges. The development of a methodology based on direct analysis of samples-time of flight-mass spectrometry (DSA-TOF-MS) made it possible to identify the main components of organic shot residues, which gave the possibility to introduce a new method of analysis of shot residues in the Chilean supply area. The DSA-TOF-MS provided extensive information on the composition of the shot residues: MC, EC, 2,4-DNT, and TNT. Samples taken from the trigger hands required minimal sample preparation that reduced analyses time. With the implementation of new alternative analytical methodologies, a great step would be taken in the analysis of OGSRs, because now there is no such technique for its analysis in Chile, and the results would also complement the existing inorganic elemental analyses generated during a gunshot.     

The evaluation of solid phase micro-extraction fibre types for the analysis of organic components in unburned propellant powders

This work describes the evaluation of various solid phase micro-extraction (SPME) fibre types for the detection of compounds originating from particles of unburned propellant powders. These compounds may also be found in association with organic gunshot residues (OGSR). Seven SPME fibres were assessed based on their ability to extract the compounds of interest (diphenylamine (DPA), 4-nitrodiphenylamine (4-NDPA), ethyl centralite (EC), nitroglycerin (NG) and dibutyl phthalate (DBP)) from four ammunition types across three calibres (9 mm, 5.56 mm and 7.62 mm). Extracts were analysed by gas chromatography/mass spectrometry (GC/MS). Results indicated that the 65 μm polydimethylsiloxane/divinylbenzene (PDMS/DVB) was the most suitable fibre type for the extraction of these compounds across the ammunition types tested. Optimal extraction time parameters were also assessed with a 35-min period determined to be suitable. A number of previously unreported considerations for extracting propellant powders and potentially OGSR related materials are discussed.     

Simultaneous Determination of Antimony and Lead in Gunshot Residue by Cathodic Adsorptive Stripping Voltammetric Methods

Differential pulse cathodic adsorptive stripping (DPCAdSV) and square wave cathodic adsorptive stripping (SWCAdSV) voltammetric methods were developed for the determination of antimony and lead in gunshot residues. Linear working ranges for DPCAdSV and SWCAdSV methods were (2.0×10^?9–5.0×10^?7) M and (2.0×10^?9–7.0×10^?7) M for antimony and 2.0×10^?9–3.0×10^?7 M (both methods) for lead. The detection of antimony limits were found to be 1.3×10^?9 M for DPCAdSV and 7.3×10^?10 M for SWCAdSV while the corresponding values for lead were 3.0×10^?9 M and 5.8×10^?10 M. Antimony and lead contents obtained by these methods in gunshot residues are in good agreement with those obtained by graphite furnace atomic absorption spectrometric method within a confidence limit of 95%.     

Separation of antimony from synthetic cloth: Application in forensic science using neutron activation analysis

Summary A simple ion-exchange separation procedure was developed for selective removal of antimony from synthetic cloth to facilitate determination of several trace elements frequently used to identify gunshot residues by neutron activation analysis. Radiotracers of Sb, Ba, Cu, Co, As, Zn, Hg and Ag were employed to optimize the developed procedure. The method involves the quantitative retention of the above elements, except of Sb, from 0.2M ammonium carbonate solution using Chelex 100 resin and subsequent quantitative elution of the elements of interest with 2M nitric acid for gamma-ray spectrometry. The procedure was tested by simulated gunshot residues.     

Simultaneous determination of inorganic and organic gunshot residues by capillary electrophoresis

A capillary electrophoresis method was developed to analyze simultaneously 11 organic and 10 inorganic components of gunshot residues as a cheaper and possibly more specific method comparing to traditional techniques. Pre-capillary complexation and simultaneously a micellar phase were combined to determine not only the metal but also the organic residues from a firearm. In order to test the possibility to apply the developed method to real cases, residues from shot samples from different firearms were analyzed and their results were compared with those obtained with electrothermal atomic absorption spectroscopy, an established technique for gunshot residue analysis. Good agreement between both techniques for lead was found.     

Dermal nitrate: an old marker of firearm discharge revisited with capillary electrophoresis

The present work describes a capillary electrophoretic method for nitrite and nitrate determination to be used as a screening tool for investigating the residues of firearm discharge. The use of capillary electrophoresis allowed the rapid determination of nitrite and nitrate, which are major inorganic components of gunshot residues, offering a quantitative and selective alternative to the traditional paraffin test (dermal nitrate test). The method is simpler, cheaper, and faster than the modern approaches to gunshot residue analysis based on the determination of barium, lead and antimony by using flameless absorption spectrometry, inductively coupled plasma-mass spectrometry (ICP-MS), or scanning electron microscopy. The analysis was carried out in a bare fused-silica capillary (75 microm inner diameter) with a 100 mM borate buffer (pH 9.24). The detection was by UV absorption at 214 nm. Separation took place under reversed voltage of 15 kV. Bromide was used as the internal standard. Sensitivity was about 1 mM for both nitrite and nitrate. Reproducibility (intraday and day-to-day) was also good with relative standard deviations (RSDs) < 1.0% for relative migration times and < 4.5% for peak areas in both standard solutions and real matrix. Hair and skin samples from a victim shot in the head were successfully analyzed for the presence of nitrite and nitrate.     

Advances ofcapillary electrophoresis in clinical and forensic analysis (1999-2000)

In this paper, capillary electrophoresis in clinical and forensic analysis is reviewed on the basis of the literature of 1999, 2000 and the first papers in 2001. An overview of progress relevant examples for each major field of application, namely (i) analysis of drug seizures, explosives residues, gunshot residues and inks, (ii) monitoring of drugs, endogenous small molecules and ions in biofluids and tissues, (iii) general screening for serum proteins and analysis of specific proteins (carbohydrate deficient transferrin, alpha1-antitrypsin, lipoproteins and hemoglobins) in biological fluids, and (iv) analysis of nucleic acids and oligonucleotides in biological samples, including oligonucleotide therapeutics, are presented.     

桃中农药残留分析及膳食暴露评估研究

为明确并量化食用桃途径的农药膳食摄入风险水平,通过对19个桃主产区采集的98份样品进行农药残留检测,对桃中的农药残留急/慢性膳食摄入风险进行评估,并借鉴英国兽药残留委员会兽药残留风险排序矩阵进行农药和样品风险排序。结果在桃中检出了38种农药残留,98个样品的检出率为95.9%,检出的农药含量为0.007 4～3.399 3 mg/kg;检出农药的慢性膳食摄入风险(%ADI)和急性膳食摄入风险(%ARfD)的平均值分别为0.89%和11.09%,风险均低于100%,不会对人体产生慢性或急性风险;风险排序结果表明桃果品中氟虫腈、硫丹、灭多威、丁硫克百威、毒死蜱、联苯菊酯为6种为高风险农药,应在生产和质量安全监管中予以重点关注。该文为桃安全消费、农药残留监管和农药最大残留限量(MRLs)制修订提供了科学依据。     

Recent advances in the applications of CE to forensic sciences (2001-2004)

The present article reviews the applications of CE in forensic science covering the period from 2001 until the first part of 2005. The overview includes the most relevant examples of analytical applications of capillary electrophoretic and electrokinetic techniques in the following fields: (i) Forensic drugs and poisons, (ii) explosive analysis and gunshot residues, (iii) small ions of forensic interest, (iv) forensic DNA and RNA analysis, (v) proteins of forensic interest, and (vi) ink analysis.     

固相萃取技术在磺胺类药物残留分析中的研究进展

磺胺类药物(Sulfonamides,SAs)残留与食品安全水平息息相关。存在SAs残留的基质复杂多样,开发快速、高效、高选择性的前处理方法是检测的关键。固相萃取(SPE)具有较少的溶剂使用量、绿色环保、高选择性、高灵敏度、节省时间、成本低、能与不同检测手段兼容等特点,已被广泛应用于SAs残留的前处理过程。该文简要介绍了移液枪头式SPE、磁性SPE、分子印迹SPE、管内SPE和其他SPE模式,并总结了它们在SAs残留检测分析中的研究进展。     

超高效合相色谱法对6种三唑类农药对映体的拆分及其在黄瓜中的残留分析

采用超高效合相色谱法（UPC²）拆分三唑酮、三唑醇、己唑醇、戊唑醇、联苯三唑醇、腈菌唑等6种三唑类农药对映体,并测定了黄瓜中6种三唑类农药对映体的残留量。样品经乙腈均质提取,石墨化炭黑（GCB）、自制弗罗里硅土柱和QuEChERS试剂依次净化后,Acquity Trefoil AMY1手性色谱柱分离,以超临界二氧化碳-甲醇等助溶剂为流动相进行梯度洗脱,外标法定量。方法定量限（S/N>10）均为0.1 mg/kg,在黄瓜中分别添加0.1、0.2、0.5 mg/kg 3个水平的三唑类农药对映体,其回收率为65.1%~116%,相对标准偏差（n=6）为1.0%~9.6%。该方法实现了对6种三唑类农药16种对映体的拆分及其在黄瓜基质中的残留测定,可为手性农药开发、使用及相关法规的制定提供科学支撑。     

Analytical methods applied to the determination of pesticide residues in foods of animal origin. A review of the past two decades

Pesticides are widely used in agriculture and can be transferred to animals in a number of ways. Consequently, reliable analytical methods are required to determine pesticide residues in foods of animal origin. The present review covers published methods and research articles (1990-2010) in which pesticide residues have been extracted from meat and meat products, milk and dairy products, fish and seafood, and eggs, then cleaned up, and isolated by chromatographic techniques to be identified and quantified by various detection methods. Recovery rates, quantification limits, the matrix effect and related parameters have all been considered. Lastly, future developments in this field are outlined.     

Surface analysis and surface measuring techniques in firearm offences

Summary When a shot is fired, the projectile and the cartridge case are released from the weapon, as well as components of the priming charge and propellant, the so-called powder-gunshot residues. In order to solve firearm offences, it is therefore very important to determine the topography of trace-bearing areas on the bullet and the cartridge case, as well as the chemical composition of gunshot residue particles. Gunshot residue particles are made visible with the scanning electron microscope (SEM) and are analysed by means of energy-dispersive X-ray spectroscopy (EDXS) and lately also by means of wavelength-dispersive X-ray spectroscopy (WDXS). In addition to this, analyses of these particles are displayed by means of Auger electron spectroscopy (AES) and secondary ion mass spectroscopy (SIMS) and depth profiles are prepared. To determine the local distributions of gunshot residue elements with regard to their quantity, the direct Zeeman atomic absorption spectroscopy (DZ-AAS) is employed. Besides the determination of the chemical composition, the topography of the trace-bearing areas on the bullet and cartridge case plays an important part. For the detection of these surfaces, light optical and electron-optical methods are employed. Moreover, the use of opto-electronical testing systems has been attracting more and more attention recently.     

Conversion of Cellulose and Lignin Residues into Transparent UV-Blocking Composite Films

The valorization of cellulose and lignin residues in an integrated biorefinery is of great significance to improve the overall economics but has been challenged by their structural recalcitrance, especially for lignin residue. In this work, a facile chemical conversion route to fabricating functional UV-blocking cellulose/lignin composite films through a facile dissolution–regeneration process using these biomass residues was proposed. Three representative lignin residues, i.e., aspen and poplar wood lignin, and corn stover (CS) lignin were assessed for their feasibility for the film fabrication. The UV-blocking performance of the composite films were comparatively investigated. Results showed that all these three lignin residues could enhance the UV-blocking property of the composite films, corresponding to the reduction in the optical energy band gap from 4.31 to 3.72 eV, while poplar lignin had a considerable content of chromophores and showed the best UV-blocking enhancement among these three assessing lignins. The enhancement of UV-blocking property was achieved without compromising the visible-light transparency, mechanical strength and thermal stability of the composite films even at 4% lignin loading. This work showed the high promise of integrating biomass residue conversion into lignocellulose biorefinery for a multi-production purpose.     

Chromatographic Techniques in Forensic Chemical Examinations

Some aspects of the use of chromatographic analytical techniques in the forensic chemical examination of materials, substances, and products were considered. The detection and subsequent expert examination of various materials (psychoactive drugs, explosives, gunshot residues, etc.) was exemplified. It was demonstrated that the effectiveness and validity of the evidential matter of expert examinations can be provided by tdeveloping a uniform system for comprehensive forensic chemical examinations of material and products; within the framework of this system, expert examinations should be performed with a required reliability and accuracy.     

Empirical prediction of protein pKavalues with residue mutation

A fast, empirical method, Mut‐pKa, is presented for predicting the pK_a values of ionizable residues in proteins based on mutation. The method compares the effect of mutating each residue that may act as a hydrogen bond donor or acceptor for the ionizable residue. The energetic effect of each type of mutation, along with a desolvation measure and the overall background charge, is fit against pK_a data for histidine and carboxyl residues. A total of 214 residues from 35 different proteins were used in the dataset. Using 11 parameters for each type of ionizable residue, a root mean squared error (RMSE) of 0.78 and 1.12 pH units were obtained for carboxyl and histidines residues, respectively, using leave one out cross validation (LOOCV). The results were particularly promising for buried residues, which had RMSE values of 0.99 and 1.13 for carboxyl and histidine residues, respectively. A number of desolvation measures were tested. The simplest measure, the number of atoms surrounding the residue, was found to work best. The effect of using dynamics was also studied using short molecular dynamics runs, followed by minimization of the structures. Mut‐pKa has significantly fewer parameters than, but similar performance to, other empirical methods. Because of this and the LOOCV results, we believe the model is robust and that overfitting is not a problem. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

Residues and dissipation of chlorothalonil and azoxystrobin in cabbage under field conditions

Chlorothalonil and azoxystrobin, as efficient and broad-spectrum fungicides, are two widely used fungicides to control downy mildew and anthracnose on cabbage. For the safe and rational use of these two pesticides on cabbage, their residues and dissipation were studied under field conditions. The trial results showed that chlorothalonil and azoxystrobin residues were affected by the frequency and dosage of application, and the weather condition post-application. Chlorothalonil and azoxystrobin dissipated rapidly in cabbage with the mean half-live of 1.7 and 0.4 days at three geographical experimental plots in China, respectively. The terminal residues of chlorothalonil and azoxystrobin in cabbage at harvest time were all below the maximum residue limit (MRL, 6 mg kg^?1 for chlorothalonil and 5 mg kg^?1 for azoxystrobin) established by Codex Alimentarius Commission. It suggested that this formulation of chlorothalonil and azoxystrobin (560 g L^?1, SC) may be safer under the recommended dosage. Given that in China no MRL has been set for chlorothalonil and azoxystrobin in cabbage, this study could provide a guidance for establishing MRL, and the safe and rational use of these two pesticides.     

Chemometric classification of gunshot residues based on energy dispersive X-ray microanalysis and inductively coupled plasma analysis with mass-spectrometric detection

A gunshot residue sample that was collected from an object or a suspected person is automatically searched for gunshot residue relevant particles. Particle data (such as size, morphology, position on the sample for manual relocation, etc.) as well as the corresponding X-ray spectra and images are stored. According to these data, particles are classified by the analysis-software into different groups: ‘gunshot residue characteristic’, ‘consistent with gunshot residue’ and environmental particles, respectively. Potential gunshot residue particles are manually checked and – if necessary – confirmed by the operating forensic scientist.