气-质联用法（EI．PCI．NCI）在系统毒物分析中的应用

本文应用电子轰击质谱(EI),正、负化学电离质谱(PCI.NCI)技术,建立了315种常见毒,药物的气一质联用系统分析方法。并建立了 EIMS、PCIMS、NCIMS 质谱图谱库。司法鉴定实践表明使用气相保留指数,特征碎片和 EI、PCI、NCI 图谱库检索等多指标的系统分析方法,是未知物鉴定的强有力的工具。     

Carbon‐Based Fingerprint Powder as a One‐Step Development and Matrix Application for High‐Resolution Mass Spectrometry Imaging of Latent Fingerprints

Carbon‐based materials are often used as matrices for matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) and its imaging (MALDI‐MSI). However, researchers have refrained from using carbon‐based fingerprint powder (CFP) as a matrix due to high background and contamination. In this work, the compatibility of CFP is reevaluated with MALDI‐MSI using a high‐resolution mass spectrometer (HRMS) and compared to traditional organic matrices. Relevant fingerprint compounds were easily distinguished from carbon cluster peaks when using HRMS. For fair comparison, half of a fingerprint was dusted with CFP while the other half was dusted with traditional organic matrices. All compounds studied had comparable, or higher, signal‐to‐noise (S/N) ratios when CFP was used as the matrix. Additionally, chemical image qualities closely followed the trend of S/N ratios. CFP proved to be an effective one‐step development and matrix application technique for MALDI‐MSI of latent fingerprints, when carbon cluster peaks are well separated by a HRMS.     

Alprazolam and Zolpidem in Skeletal Tissue of Decomposed Body Confirms Exposure

In several medico‐legal cases, bone samples analysis may provide the only source of toxicological information. This case study reports the analysis of a human bone specimen, belonging to a 46‐year‐old man, found 3 months after his death due to cervical–thoracic injuries in a motorcycle accident. Bone specimen was the only available material for toxicological analysis, among few skull hair and rotten skin. Analysis was performed by a newly developed and validated ultra‐high‐pressure liquid chromatography–mass spectrometry/mass spectrometry (UHPLC‐MS/MS) method, following simple and efficient sample pretreatment. The results were in accordance with the man's medical record: Alprazolam and zolpidem were found at 2.2 and 5.4 ng/g of bone, respectively. Both these drugs were prescribed to the deceased.     

Secondary transfer of organic gunshot residues: Empirical data to assist the evaluation of three scenarios

The present study aimed at providing data to assess the secondary transfer of organic gunshot residues (OGSR). Three scenarios were evaluated in controlled conditions, namely displacing a firearm from point A to point B, a simple handshake and an arrest involving handcuffing on the ground. Specimens were collected from the firearm, the hands of the shooter and the non-shooter undergoing the secondary transfer in order to compare the amounts detected.Secondary transfer was observed for the three scenarios, but to a different extent. It was found that displacing a firearm resulted in secondary transfer in <50% of the experiments. The firearm also had an influence, as contrary to the pistol, no secondary OGSR were detected using the revolver. Shaking the hand of the shooter also transferred OGSR to the non-shooter's hand. In that case, the amount of OGSR was generally higher on the shooter than on the non-shooter. Finally, the largest secondary transfer was observed after the arrest with handcuffing with positive results in all cases using the pistol. In that scenario, the amounts on the shooter and the non-shooter were in the same range.This study highlights that the secondary transfer must be taken into account in the interpretation of OGSR. Indeed, an individual's hands might be contaminated by handling a firearm or having physical contact with a shooter.     

STREET NETWORK STRUCTURE AND CRIME RISK: AN AGENT‐BASED INVESTIGATION OF THE ENCOUNTER AND ENCLOSURE HYPOTHESES

Street networks shape day‐to‐day activities in complex ways, dictating where, when, and in what contexts potential victims, offenders, and crime preventers interact with one another. Identifying generalizable principles of such influence offers considerable utility to theorists, policy makers, and practitioners. Unfortunately, key difficulties associated with the observation of these interactions, and control of the settings within which they take place, limit traditional empirical approaches that aim to uncover mechanisms linking street network structure with crime risk. By drawing on parallel advances in the formal analyses of street networks and the computational modeling of crime events interactions, we present a theoretically informed and empirically validated agent‐based model of residential burglary that permits investigation of the relationship between street network structure and crime commission and prevention through guardianship. Through the use of this model, we explore the validity of competing theoretical accounts of street network permeability and crime risk—the encounter (eyes on the street) and enclosure (defensible space) hypotheses. The results of our analyses provide support for both hypotheses, but in doing so, they reveal that the relationship between street network permeability and crime is likely nonlinear. We discuss the ramifications of these findings for both criminological theory and crime prevention practice.     

Quantitative Determination of Cannabinoids in Cannabis and Cannabis Products Using Ultra‐High‐Performance Supercritical Fluid Chromatography and Diode Array/Mass Spectrometric Detection

Ultra‐high‐performance supercritical fluid chromatography (UHPSFC ) is an efficient analytical technique and has not been fully employed for the analysis of cannabis. Here, a novel method was developed for the analysis of 30 cannabis plant extracts and preparations using UHPSFC /PDA ‐MS . Nine of the most abundant cannabinoids, viz . CBD , ?⁸‐THC , THCV , ?⁹‐THC , CBN , CBG , THCA ‐A, CBDA , and CBGA , were quantitatively determined (RSD s < 6.9%). Unlike GC methods, no derivatization or decarboxylation was required prior to UHPSFC analysis. The UHPSFC chromatographic separation of cannabinoids displayed an inverse elution order compared to UHPLC . Combining with PDA ‐MS , this orthogonality is valuable for discrimination of cannabinoids in complex matrices. The developed method was validated, and the quantification results were compared with a standard UHPLC method. The RSD s of these two methods were within ±13.0%. Finally, chemometric analysis including principal component analysis (PCA ) and partial least squares‐discriminant analysis (PLS ‐DA ) were used to differentiate between cannabis samples.     

Application of MALDI‐TOF MS for Estimating the Postmortem Interval in Rat Muscle Samples

Estimating the postmortem interval (PMI) is very important in the forensic sciences. Although many approaches have been used for estimating the PMI, accurate PMI calculations are still difficult. In this study, four Sprague Dawley (SD) rats were sacrificed by suffocation, and muscle samples were collected by dissection at various time intervals (0, 48, 96, and 144 h) after death. All samples were probed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) to obtain molecular images and data for principal component analysis (PCA). The results showed that the peaks at m/z 1511, 1543, 1564, 1586 clearly decreased in intensity from 0 to 144 h postmortem and that the time groups were separated from each other on the PCA score plot. The prediction model showed high recognition capability (95.93%) and cross‐validation (83.72%). Our work suggests that MALDI‐TOF MS can be used to determine the PMI.     

Feasibility of Canine Detection of Mass Storage Devices: A Study of Volatile Organic Compounds Emanating from Electronic Devices Using Solid Phase Microextraction

Detection of canines are well‐known to be valuable in the location of contraband, such as explosives or narcotics. More recently, canines have been trained and utilized in the detection of concealed mass storage devices that might contain evidence of illegal activity such as child pornography. To lay the analytical foundation for this detection work, research was carried out to determine the volatile organic compounds associated with mass storage devices (MSD) that could be used by trained canines for detection. Headspace analysis of a variety of electronic devices was performed using solid phase microextraction (SPME) with gas chromatography/mass spectrometry (GC/MS). Analyses found several volatile compounds common to SIM and SD cards, as well as USB drives, including 2‐propenenitrile, styrene, isophorone, hydroxycyclohexyl phenyl ketone, and 2‐furanmethanol, tetrahydro. Results indicated that mass storage devices do have a characteristic odor profile making detection with minimal false alerts feasible for trained canines.     

China's stance on the Google/Motorola merger: Implications for competition in intellectual property-intensive sectors

China's merger enforcement agency approved the Google/Motorola merger with conditions. This pattern of approval is not in full accordance with that in other jurisdictions, including the United States and the European Union, which made unconditional approvals. This contradiction attracted ample criticism; some critics believe that China's policy is designed to protect domestic industry. In investigating the Chinese merger agency's decision and the basis for its decision making, this article finds that much of the criticism is groundless and misleading because the critics have failed to incorporate all elements of the global value chain of mobile intelligent terminals into their analyses. The investigation also shows that, although the decision makers are less experienced, their decisions are based on Chinese competition law and market realities. It is important for international firms to be aware of this pattern in merger analysis.     

SPE-HPLC/MS/MS检验体液中赛拉嗪及DMA

目的建立了一种高效液相色谱串联三重四极杆质谱同时测定体液中赛拉嗪及2,6-二甲基苯胺的分析方法。方法样品经HLB固相萃取柱提取净化,Waters Atlantis d C18色谱柱分离,正电离条件下进行选择监视扫描模式检测。结果方法的回收率为70.5%~79.8%,RSD为8.2%~10.5%。赛拉嗪及2,6-二甲基苯胺在血液和尿液中的检出限分别为0.4 ng/mL和0.3 ng/mL,定量限分别为1.2 ng/mL和1.0 ng/mL。结论本方法灵敏度高、特异性好、重现性好,适用于赛拉嗪中毒的血液和尿液检测。