Review of analytical techniques for arson residues

Arson is a serious crime that affects society through cost, property damage, and loss of life. It is important that the methods and technologies applied by fire investigators in detection of evidence and subsequent analyses have a high degree of reliability, sensitivity, and be subject to rigorous quality control and assurance. There have been considerable advances in the field of arson investigation since the 1950s. Classification of ignitable liquids has been updated to include many new categories due to developments in the petroleum industry. Techniques such as steam or vacuum distillation and gas chromatography (GC) with flame ionization detection that may have been considered acceptable--even a benchmark--40 years ago, are nowadays generally disfavored, to the extent that their implementation may almost be considered as ignorance in the field. The advent of readily available mass spectrometric techniques has revolutionized the field of fire debris analysis, increasing the degree of sensitivity and discrimination possible considerably. Multi-dimensional GC--particularly GC x GC--while not yet widely applied, is rapidly gaining recognition as an important technique. This comprehensive review focuses on techniques and practices used in fire investigation, from scene investigation to analysis.     

血液和脑脊液中利多卡因的气相色谱-质谱检测研究

目的建立血液和脑脊液中利多卡因的气相色谱-质谱联用定性、定量检测方法。方法血液或脑脊液盐酸酸化后,氢氧化钠碱化(pH=9),乙醚提取,氮气流下挥干,乙醇定容,气相色谱-质谱联用仪分析,选择离子监测模式检测(86,58,72,87),定性、定量检测血液和脑脊液中利多卡因。结果血液和脑脊液中利多卡因的线性范围为1.0～60.0μg·mL-1(r=0.9999),检出限为0.02μg·mL-1(S/N=3),加样回收率为85%～103%,麻醉致死犬血液和脑脊液中检出利多卡因,结果满意。结论该法选择性好,干扰少,灵敏,准确,可用于生物体液中利多卡因的定性和定量检测。     

国内外液态爆炸物安全检查技术和设备的发展

液态爆炸物具有制造简易、不易识别、威力巨大、易于引爆等特点,这些特点增加了液态爆炸物安全检查的难度。液态爆炸物的安全检查分为探测、防护和处置三个环节。针对探测环节,文章综述了国内外主要使用的液态爆炸物探测技术及其特点,介绍了有代表性的技术产品,探讨了液态爆炸物探测技术的发展趋势,最后,对我国液态爆炸物安全检查行业的技术发展提出了几点建议。     

Simultaneous Quantitative Determination of Amphetamines,Opiates, Ketamine,Cocaine and Metabolites in Human Hair: Application to Forensic Cases of Drug Abuse

A method using liquid chromatography–tandem mass spectrometry (LC–MS/MS) to simultaneously quantify amphetamines, opiates, ketamine, cocaine, and metabolites in human hair is described. Hair samples (50 mg) were extracted with methanol utilizing cryogenic grinding. Calibration curves for all the analytes were established in the concentration range 0.05–10 ng/mg. The recoveries were above 72%, except for AMP at the limit of quantification (LOQ), which was 48%. The accuracies were within ±20% at the LOQ (0.05 ng/mg) and between −11% and 13.3% at 0.3 and 9.5 ng/mg, respectively. The intraday and interday precisions were within 19.6% and 19.8%, respectively. A proficiency test was applied to the validated method with z-scores within ±2, demonstrating the accuracy of the method for the determination of drugs of abuse in the hair of individuals suspected of abusing drugs. The hair concentration ranges, means, and medians are summarized for abused drugs in 158 authentic cases.     

Identification of Opioids and Related Substances using Handheld Raman Spectrometers

This study describes the performance of handheld Raman devices for detecting one hundred opioids and related substances including fentanyl and several analogs. Using a single “parent” device, signatures (spectra) with excellent signal-to-noise ratios were generated using <5 mg of most compounds. The signatures were added to a method (library), which was electronically transferred to three “daughter” devices. The devices were able to discriminate different salt forms and isomers. On average, the daughter devices yielded a true-positive rate of 97.3% for generating an alarm for opioids and were 93.3% effective for correctly identifying the opioid. The devices yielded true-negative, false-positive and false-negative rates of 100%, 0%, and 2.7%, respectively, where false negatives were due to weak signal and fluorescence. These data demonstrate that the parent-daughter electronic transfer method was successful and effective, which permits the ability to develop methods in the laboratory that can be seamlessly pushed out to field devices.     

Toner Particles as Forensic Evidence: Microanalytical Characterization of Known Toner and Recognition of Toner in Environmental Samples*†‡

Modern printing toners represent a prime example of subvisible particles that can be easily transferred to hands, clothing, and other surfaces. To explore the potential evidentiary value of toner particles, toner samples were collected from known printer cartridges and characterized by various microanalytical techniques to establish the properties most useful for recognition, identification, and comparison. Environmental samples (i.e., dust) were then collected from various locations at varying distances from toner-based printers, using both tape lifts and carbon adhesive stubs, to assess the possibility of detecting toner. By light microscopy, toner can be recognized on the basis of particle size and shape, as well as color. Further examination of the micromorphology in the field emission scanning electron microscope reveals characteristic morphologies and differences in surface texture and shape among toner sources. Raman spectroscopy provides chemical identification of the pigment (or pigment class) and, in some cases, also permits identification of the polymer component. While black and blue pigment chemistry remained constant among toner varieties that were studied (copper phthalocyanine and carbon black), variation in yellow and magenta pigments was observed. Analysis of dust samples collected from various environments demonstrated that while toner is consistently detectable in close proximity to printers (within 2 feet), it also can be detected in dust collected in nearby rooms. This research demonstrates that toner particles can be located, characterized, and discriminated, using a suite of microanalytical methods that are applicable to forensic casework.     

Fast Discrimination of Marijuana using Automated High-throughput Cannabis Sample Preparation and Analysis by Gas Chromatography–Mass Spectrometry

In the United States, federal law and many state laws differentiate between marijuana and industrial hemp through delta-9-tetrahydrocannabinol (THC) levels, whereby the latter is defined as ≤0.3 percent THC on a dry weight basis. Many traditional cannabis identification methods employed by crime laboratories cannot accurately determine total THC quantities in accordance with federal and state regulations, or do so with increased time, labor, and risks of instrument damage. In order to quickly distinguish positive marijuana samples, a method was developed to identify plant material with a total THC level >1%. This novel, automated dispersive pipette extraction (DPX) method uses tip-based technology and an automated liquid handler to enable fast, hands-free selective isolation of THC and its precursors for downstream gas chromatography–mass spectrometry (GC-MS) analysis. The workflow proceeds with no repetitive manual effort and reduced need for instrument maintenance while enabling crime labs to legally identify marijuana through the detection of total THC above 1%. Recovery of THC using the DPX extraction method was 93% at 30 µg/mL and 78% at 500 µg/mL. Similarly, THCA-A recovery was 100% at 30 µg/mL and 74% at 500 µg/mL. Samples evaluated in a blind study (proficiency, hemp, and nonprobative case samples) were all accurately identified as greater than or less than 1% THC, with samples containing <1% THC being identified as “cannabis” and subjected to more discriminative analysis as needed.     

鱼塘水中微量铜的原子吸收检验

采用原子吸收检验测定因投放铜盐导致鱼大批死亡的鱼塘水中的微量铜以空白鱼塘水为对照,铜标准液做标准曲线,方法简单,结果准确可靠,是该类案件检测的较好方法之一.     

海洛因来源鉴定的新方法

毒品来源的鉴定是指对毒品样品中包含的来源信息进行提取拜分析,这有助于打击毒品犯罪.海洛因是危害我国的主要毒品,它的来源鉴定更引起人们的关注.本文介绍了国际上研究海洛因来源的三种方法,即研究海洛因样品中的各种有机杂质及其相对比例;研究海洛因样品中的痕量无机元素;研究海洛因及吗啡的稳定同位素相对比值.第三种方法能够反映样品的地域性特点,因而在来源鉴定方面有突出的优势.气相色谱-燃烧-同位素比值质谱法是同位素比值测定方法中用于海洛因来源鉴定的最佳手段.这一技术还可用于其他微量物证(如炸药、药品、油品等)的来源鉴别,因而在法庭科学领域内显示了广阔的应用前景.     

Short term impact of Tribulus terrestris intake on doping control analysis of endogenous steroids

Tribulus terrestris is a nutritional supplement highly debated regarding its physiological and actual effects on the organism. The main claimed effect is an increase of testosterone anabolic and androgenic action through the activation of endogenous testosterone production. Even if this biological pathway is not entirely proven, T. terrestris is regularly used by athletes. Recently, the analysis of two female urine samples by GC/C/IRMS (gas chromatography/combustion/isotope-ratio-mass-spectrometry) conclusively revealed the administration of exogenous testosterone or its precursors, even if the testosterone glucuronide/epitestosterone glucuronide (T/E) ratio and steroid marker concentrations were below the cut-off values defined by World Anti-Doping Agency (WADA). To argue against this adverse analytical finding, the athletes recognized having used T. terrestris in their diet. In order to test this hypothesis, two female volunteers ingested 500 mg of T. terrestris, three times a day and for two consecutive days. All spot urines were collected during 48 h after the first intake. The (13)C/(12)C ratio of ketosteroids was determined by GC/C/IRMS, the T/E ratio and DHEA concentrations were measured by GC/MS and LH concentrations by radioimmunoassay. None of these parameters revealed a significant variation or increased above the WADA cut-off limits. Hence, the short-term treatment with T. terrestris showed no impact on the endogenous testosterone metabolism of the two subjects.