The fate of the chemical warfare agent during DNA extraction

Forensic laboratories do not have the infrastructure to process or store contaminated DNA samples that have been recovered from a crime scene contaminated with chemical or biological warfare agents. Previous research has shown that DNA profiles can be recovered from blood exposed to several chemical warfare agents after the agent has been removed. The fate of four toxic agents, sulfur mustard, sodium 2-fluoroacetate, sarin, and diazinon, in a lysis buffer used in Promega DNA IQ extraction protocol was studied to determine if extraction would render the samples safe. Two independent analytical methods were used per agent, selected from GC-MS, 1H NMR, 19F NMR, (31)P NMR, or LC-ES MS. The methods were validated before use. Determinations were carried out in a semi-quantitative way, by direct comparison to standards. Agent levels in the elution buffer were found to be below the detectable limits for mustard, sarin, sodium 2-fluoroacetate or low (<0.02 mg/mL) for diazinon. Therefore, once extracted these DNA samples could be safely processed in a forensic laboratory.     

Gunshot residue in Chicago police vehicles and facilities: an empirical study

Suspects in shooting investigations in Chicago are routinely transported in department vehicles and detained in department facilities prior to gunshot residue (GSR) evidence collection. The GSR test results are used to associate the suspect with primary exposure to GSR. The potential for these vehicles and facilities being sources of secondary GSR contamination needed to be determined. A total of 201 samples were collected from randomly selected vehicles and detention facilities. The sampling collected trace materials from surfaces that suspects' hands may contact during the arrest process. These samples were examined for the presence of GSR particles using scanning electron microscopy. Upon completion of the automated analysis, those particles that met an initial GSR screening criterion were relocated and reanalyzed. The locations where GSR particles were recovered allowed us to make recommendations to the Chicago Police Department with regard to transporting and detaining these suspects. The low number of GSR particles recovered suggests that the potential for secondary contamination, although present, is relatively low.     

Quick Screening of Crystal Methamphetamine/Methyl Sulfone Exhibits by Raman Spectroscopy

Abstract: The analysis of mixtures of “crystal meth” (usually comprised of methyl sulfone [MS] and methamphetamine [MA]) by gas chromatography‐mass spectrometry (GCMS) is routine in many forensic drug laboratories. The utilization of Raman spectroscopy for the identification of such mixtures quickly and without the need for a separation technique is discussed. Samples were dissolved in water and Raman spectra of the resulting aqueous solutions were collected. By comparing these spectra to spectra of methylsulfone and MA mixtures of known composition, an indication of the composition of the sample can be obtained in only a few minutes. This spectral comparison also can be used as a semi‐quantitative analysis of MA concentrations in such exhibits.     

Optical Characterization of Some Modern “Eco‐Friendly” Fibers*

Abstract: Fibers that are termed “eco‐friendly” or “biodegradable” by manufacturers are increasingly being used in textile products such as apparel and carpeting to appeal to the ever more environmentally aware public. As such, these modern fibers are expected to begin showing up more often in forensic casework, and it is important that the forensic examiner recognize them. This study employed polarized light microscopy (PLM) and Fourier transform infrared (FTIR) microspectroscopy to characterize selected fibers of azlon, polylactic acid (PLA), cellulose composites of alginate or chitin, and bamboo (viscose rayon). Fiber cross‐sections, refractive indices, melting points, solubilities, and FTIR measurements were conducted. Results indicate that the azlons and PLA fibers are easily distinguishable from other textile fibers by their optical and chemical properties. The cellulose composites show only small differences in comparison with other cellulose‐based fibers, while bamboo viscose rayon is indistinguishable from normal viscose rayon.     

Visualization of Aged Fingerprints with an Ultraviolet Laser

Detection of aged fingerprints is difficult because they can degrade over time with exposure to light, moisture, and temperature. In this study, aging fingerprints were visualized by time‐resolved spectroscopy with an ultraviolet‐pulsed laser. Fingerprints were prepared on glass slides and paper and then stored under three lighting conditions and two humidity conditions for up to a year. The fluorescence intensities of the fingerprints decreased with time. Samples were stored in the dark degraded less than in sunlight or under a fluorescent lamp. Samples were stored under low humidity degraded less than under moderate humidity. As the storage period increased, a fluorescence emission peak appeared that was at a longer wavelength than the peak visible in earlier spectra. This peak was used for visualization of an aged fingerprint over time. An image of the fingerprint was not initially visible, but an image appeared as the time since deposition of the fingerprint increased.     

Controversial Suicide Case Using a Submachine Gun with a Sound Suppressor—The Need of Team Work of Forensic Chemistry and Firearm Examiners

Evidence materials in a presumed suicide case were studied by a firearm examiner and a forensic chemist. The victim's body with double gunshot wounding in his forehead, a machine gun in the sustained fire mode with a silencer, and four cartridge cases were found. Examinations of the evidence, the case file studies, and experiments dedicated to the case were carried out. Relationships between the placement of cartridge cases and the gun were established using a fast camera. The distributions of gunshot residues on the evidence materials and within the comparative gunshot patterns were studied by means of optical and electron microscopy, X‐ray microanalysis, and infrared spectroscopy. The shooting distance was assessed to be 30 cm or more, whereas the greatest distance that could have been achieved by the victim himself was about 11–13 cm. The obtained results supported the version of homicide rather than suicide.     

二乙酰吗啡盐酸盐标准物质的研制（2）-定值和不确定度评定

目的对研制的二乙酰吗啡盐酸盐标准物质进行定值,并评定定值结果的不确定度。方法采用定量核磁共振法和质量平衡法进行定值;采用液质联用法用于有机物杂质的定性分析,采用电感耦合等离子质谱法、离子色谱法、顶空-气质联用法和卡尔费休滴定法测定无机阳离子、阴离子、挥发性有机溶剂残留和水分等杂质的含量。结果定量核磁共振法的纯度为95．6％,不确定度为0．13％;质量平衡法的纯度为95．3％,不确定度为0．93%。结论二乙酰吗啡盐酸盐标准物质的纯度值为95．6％,扩展不确定度为1．2％（k=2）。     

磁珠DNA自动提取系统在法医检验中的应用

磁珠DNA自动提取系统是将磁珠分离技术与DNA自动提取工作站结合运用,以达到高效提取DNA的目的,它具有操作时间短、准确性高、检材用量少等特点,特别适用于大批量生物检材的快速提取,是目前主流的DNA自动化提取方法。本文对磁珠DNA自动提取系统的基本组成、工作原理、操作流程及其在法医检验领域中的应用等进行了综述,并对该系统的发展前景进行了展望。     

Analysis and Discrimination of Single‐Layer White Architectural Paint Samples,

Comparative analyses of 50 single‐layer white architectural paints were conducted to determine the discrimination power using standard techniques and to provide a basis for assessing significance when paints with limited features are not discriminated. Utilizing Fourier transform infrared spectroscopy (FTIR), 68 undifferentiated pairs resulted, yielding a discrimination of 94.45%. Adding stereomicroscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and backscatter electron (BSE) imaging, and pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), the overall discrimination was 99.35%. The study included blind verification replicates, which resulted in the only pairs without indications of physical or chemical differences. The remaining groups of undifferentiated samples contained subtle differences by at least one technique, but were considered undifferentiated for the discrimination power evaluations. This study demonstrates a high degree of discrimination of single‐layer white architectural paints using methods of analysis often encountered in forensic science laboratories.     

Raman Spectroscopy as a Simple,Rapid, Nondestructive Screening Test for Methamphetamine in Clandestine Laboratory Liquids

Raman spectroscopy has found increased use in the forensic controlled substances laboratory in recent years due to its rapid and nondestructive analysis capabilities. Here, Raman spectroscopy as a screening test for methamphetamine in clandestine laboratory liquid samples is discussed as a way to improve the efficiency of a laboratory by identifying the most probative samples for further workup among multiple samples submitted for analysis. Solutions of methamphetamine in ethanol, diethyl ether, and Coleman fuel were prepared in concentrations ranging from 0.5% to 10% w/v, and Raman spectra of each were collected. A concentration‐dependant Raman peak was observed at 1003 per cm in each solution in 4% w/v and greater solutions. Case samples were analyzed and also found to reliably contain this diagnostic peak when methamphetamine was present. The use of this diagnostic indicator can save the forensic controlled substances laboratory time and materials when analyzing clandestine laboratory liquid submissions.