Preparation of pyrolysis reference samples: evaluation of a standard method using a tube furnace

A new, simple method for the reproducible creation of pyrolysis products from different materials that may be found at a fire scene is described. A temperature programmable steady-state tube furnace was used to generate pyrolysis products from different substrates, including softwoods, paper, vinyl sheet flooring, and carpet. The temperature profile of the tube furnace was characterized, and the suitability of the method to reproducibly create pyrolysates similar to those found in real fire debris was assessed. The use of this method to create proficiency tests to realistically test an examiner's ability to interpret complex gas chromatograph-mass spectrometric fire debris data, and to create a library of pyrolsates generated from materials commonly found at a fire scene, is demonstrated.     

A New Kind of Molotov? Gasoline–Pool Chlorinator Mixtures*

This paper investigates the reaction between pool chlorinators and gasoline. In particular, the propensity for self-ignition and the resulting chemical products were studied. An organic pool chlorinator was combined with gasoline in varying proportions in an attempt to form a hypergolic mixture. None of the combinations resulted in self-ignition, but larger quantities of chlorinator produced vigorous light-colored smoke and a solid mass containing isocyanuric acid and copper chloride. Additionally, the chlorinating abilities of different commercially available pool chlorinators were explored. When Ca(ClO)(2) and sodium dichloro-s-triazinetrione-based chlorinators were used, the presence of gasoline was still visible after 10 days, despite limited chlorination. The trichloro-s-triazinetrione-based chlorinator, however, caused efficient chlorination of the C(2)- and C(3)-alkylbenzenes, making gasoline no longer identifiable.     

Performance Testing of the New AMPAC Fire Debris Bag Against Three Other Commercial Fire Debris Bags(*)

Abstract: Fire debris evidence is collected and stored in a wide range of containers, including various polymer bags. Four different polymer bags have been investigated, including the NYLON, DUO, ALU, and AMPAC bags. The latter is the successor of the Kapak Fire DebrisPAK^?. Microscopy and infrared spectroscopy were used to elucidate the composition of the bags. Gas chromatography/mass spectrometry was used to investigate performance parameters such as background volatiles, leak rate, cross‐contamination, recovery, and sorption. The NYLON bag was susceptible for leakage and cross‐contamination and showed decreased recoveries. The DUO and ALU bags showed some background volatiles, sorption, and poor recoveries. The AMPAC bag performed excellent: low background, no leakage or cross‐contamination, good recoveries, and only traces of sorption. Heat sealing proved to be the best method of closure. Preliminary studies on AMPAC bags showed that polyethylene clamps are easy to use on‐site and preserve ignitable liquids adequately for a limited period of time.     

Preparation and characterization of micro-bore wall-coated open-tubular capillaries with low phase ratios for fast-gas chromatography–mass spectrometry: Application to ignitable liquids and fire debris

Fast Gas Chromatography (GC) allows for analysis times that are a fraction of those seen in traditional capillary GC. Key modifications in fast GC include using narrow, highly efficient columns that can resolve mixtures using a shorter column length. Hence, a typical fast GC column has an inner diameter of 100–180 μm. However, to maintain phase ratios that are consistent with typical GC columns, the film thickness of fast GC stationary phases are also low (e.g., 0.1–0.18 μm). Unfortunately, decreased film thickness leads to columns with very low sample capacity and asymmetric peaks for analytes that are not sufficiently dilute. This paper describes micro-bore (50 μm i.d.) capillary columns with thick films (1.25 μm), and low phase ratios (10). These columns have greater sample capacity yet also achieve minimum plate heights as low as 110 μm. Hence, separation efficiency is much higher than would be obtained using standard GC columns. The capillary columns were prepared in-house using a simple static-coating procedure and their plate counts were determined under isothermal conditions. The columns were then evaluated using temperature programming for fast GC–MS analysis of ignitable liquids and their residues on fire debris exemplars. Temperature ramps of up to 75 °C min^?1 could be used and separations of ignitable liquids such as gasoline, E85 fuel, and lighter fluid (a medium petroleum distillate) were complete within 3 min. Lastly, simulated fire debris consisting of ignitable liquids burned on carpeting were extracted using passive headspace absorption-elution and the residues successfully classified.     

The use of liquid latex as a pre-treatment to recover debris-covered latent fingerprints from exterior surfaces of vehicles

This study evaluated the effectiveness of using liquid latex as a pre-treatment for fingerprint recovery from the exterior surfaces of vehicles in summer. The sample of this study was 540 sebaceous latent fingerprints deposited on the lower body of three vehicles. Thirty control and thirty experimental fingerprints were deposited on each vehicle, and the experiment was repeated three times. The three vehicles were driven daily for either 2, 3, or 4 weeks after the deposition of fingerprints. After the vehicles reached their designated debris accumulation duration, the latent fingerprints in the control groups were developed with black fingerprint powder. Liquid latex was applied onto the fingerprints in the experimental groups, and they were subsequently developed with black fingerprint powder. A chi-sure test indicated that there was a significant difference in fingerprints recovery performance between two methods (X² = 4.903, d.f. = 1, p = 0.027). An odds ratio test indicated the control method increases the probability of fingerprint recovery by 1.54 times. A Fisher's exact test was used to evaluate the quality of fingerprints recovered from both methods and it indicated that there is no significant difference in quality using the two methods (p = 0.058). This study indicated that the traditional fingerprint powder method performed better for fingerprint recovery from exterior surfaces of vehicles in summer.     

Practical Aspects of Analyzing Vegetable Oils in Fire Debris*

Abstract: Vegetable oils undergo burning, self‐heating, and spontaneous ignition, resulting in their presence in fire debris. As these processes can affect the fatty acid content of vegetable oils, it is important that debris be properly handled in order to obtain reliable and informative data. This research investigated changes in vegetable oil content as a result of storage conditions and different types of burning. Material spiked with vegetable oils and burned was stored under various long‐term conditions, and debris was tested by heating overnight using passive headspace concentration. Results indicated that refrigeration is ideal for fire debris samples suspected of containing vegetable oils and that including passive headspace concentration in the analytical scheme would not affect oils. Spontaneous ignition experiments were conducted to compare the effects of various burning processes on vegetable oil content. Vegetable oils that experienced nonpiloted ignition, self‐heating, and spontaneous ignition produced noticeably different chromatograms from those that underwent piloted ignition.     

“负责任外空行为”议程与太空安全机制新动向

近年来,太空安全环境发生急剧变化,各国太空军事化步伐加速,商业航天崛起,太空拥挤加剧,太空军民融合加深。在此背景下,英国于2020年发起一项名为“负责任外空行为”的太空军控新议程。该议程推出后,美国积极参与并试图将之导向一项自愿承诺禁止地基动能反卫星试验的国际协议,这意味着其太空军控立场的重大转向。美国意图借“负责任外空行为”议程干扰对手发展不对称反卫星手段、强化太空同盟、划定太空威慑“红线”、策应太空环境议题。“负责任外空行为”已成为太空安全机制领域最有影响力的议程,不仅因为其引发了大国间政治矛盾,还因其体现了太空安全机制的发展动向。在新的太空安全环境下,太空军事安全和民事安全的国际机制正交叉融合发展,各机制的议程模式将更加开放、参与者更加多样、控制行为的路径更加主流。     

ATD—GC—MS法测定火场样品中痕量汽油燃烧残留物

目的为火场样品中痕量汽油残留物的检测建立一种简便、高灵敏度的检验方法和可靠的检验结果评判方法。方法用TenaxTA吸附管吸附富集火场样品中的汽油成分,然后用ATD—GC—MS法自动解吸和检测。通过模拟燃烧实验,探讨了检验结果的评判方法：根据样品的m／z（57＋85）、m/z（91＋105＋119）、m／z（117＋131）和m/z（128＋142＋156）四个质量色谱图与已知汽油作比较来对检验结果作评判。结果6组模拟燃烧实验中凡有汽油作助燃剂的样品．均检出汽油残留物成分。结论所建立的方法具有操作简便,检测灵敏度高,杂质干扰少,定性结论准确可靠等特点。可用于实际火场样品中痕量汽油残留物的检测。     

An Evaluation of Standardized Software for Processing GC/MS Data from Different Vendors' Instruments in a Forensic Laboratory

Forensic science laboratories perform analyses on a variety of materials using gas chromatography/mass spectrometry (GC/MS). Instruments from different vendors may be used, requiring analysts to be proficient in the use of multiple proprietary software packages for collecting and processing data. There is no standardized GC/MS software available that can acquire data from different vendors' instruments. However, there are third‐party processing software products that can import data files in different formats. The Centre of Forensic Sciences compared the data processing performance of one such product, ACD/MS Manager Suite, with three instrument vendors' software used for casework analysis. This product was tested for its compatibility with the existing software, its capability to load and present data, and to initiate searches of commercial libraries. The study shows that the MS Manager module provides a means for the forensic analyst to view, process, and report on data from different sources in one software package.     

中美火箭残骸碰撞事件引发的法律责任问题思考

随着人类探索和利用外层空间的迅速发展,外空环境中的空间碎片急剧增加,发生空间物体损害责任事故的可能性随之日益增大。中美火箭残骸碰撞事件引发了作者对《空间物体造成损害的国际责任公约》能否有效应对当前责任事故的思考。基于空间开发新形势的需要,有必要对该公约进行修改和完善。