Forensic Chemistry最新文献

Electrodeposition of redox materials with potential for enhanced visualisation of latent finger-marks on brass substrates and ammunition casings.

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-04-19 DOI: 10.1016/j.forc.2025.100663

Colm McKeever, Eithne Dempsey

Electrochemical methods can play a key role in the analysis of impression evidence, specifically, latent finger-marks on brass substrates and ammunition casings, the latter being commonly encountered at crime scenes in forensic casework. In adopting such techniques, forensic investigators can potentially overcome some of the challenges associated with traditional visualisation methods, the use of aggressive reagents, preservation of evidence integrity and the need for extensive sample preparation. The spatially selective deposition of conducting/redox active polymers for visualising latent finger-marks on typically low-yield brass ammunition casings is examined here, exploiting the electrodeposition of 3,4-ethylenedioxythiophene (EDOT), together with a first-time study of phenozine vs. phenothiazine monomers, and their combinations at sheet and cartridge brass. Fine tuning of electrochemical protocols and conditions together with optimised monomer feedstocks played a key role in the finger-mark visualisation quality achieved with insights into brass electrochemistry. EDOT-thionine emerged consistently as the most effective combination upon electrochemical deposition on brass sheets, revealing latent finger-marks (groomed) at the highest level of detail (level 3), including pores within the papillary ridges, using a low energy, rapid (t = 120 s) constant potential (E_app = 0.1 V vs Ag|AgCl) approach. Successful visualisation of groomed and natural (donor) latent finger-marks was achieved following exposure of brass to temperatures of 700 °C and > 15-month room temperature aging. Bespoke electrochemical cells designed to facilitate the use of ammunition casings as working electrodes produced excellent results via potential sweeping, resulting in pristine visualised latent finger-marks (groomed) of grade 3 quality with visible level 3 (> 50 %) features.

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引用次数: 0

Application of the expert algorithm for substance identification (EASI) to the electron ionization (EI) mass spectra of fentanyl isomers and analogs

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-04-09 DOI: 10.1016/j.forc.2025.100660

Alexandra I. Adeoye , Glen P. Jackson

Fentanyl analogs (fentalogs) share many structural and mass spectral similarities that make them difficult to differentiate and accurately identify without chromatographic data. In such situations, the expert algorithm for substance identification (EASI) provides superior classification relative to conventional approaches. Using a database of >57,000 replicate electron-ionization mass spectra of 76 fentalogs from ten laboratories, three challenging sets of isomers were studied in detail. To maximize limits of detection, only the 20 most abundant ions were considered. In each case, 50 % of the data from one laboratory served as the training set. On average, the mean absolute residuals between measured and modeled abundances of known positives were five times smaller using EASI than the consensus approach, which used the means of training sets as the exemplar spectra to which all query spectra were compared. With a conservative threshold of zero false positives, EASI identified isovalerylfentanyl from its two closest isomers with an accuracy of 96.7 %, which was ∼10 % better than the consensus approach. The associated positive likelihood ratios increased from 366 for the consensus approach to more than 4,200 for EASI. When discriminating isovalerylfentanyl spectra from the other 72 fentalogs, EASI provided errorless results with a positive likelihood ratio exceeding 50,000. For all 9 fentalogs, EASI outperformed the consensus approach and the use of Mahalanobis distance as a metric for identifying outliers. In the absence of retention time information, EASI improves confidence in drug identifications, enables inter-laboratory identifications, and reduces the need for acquiring concomitant spectra of standards.

芬太尼类似物（fentalogs）在结构和质谱上有许多相似之处，因此在没有色谱数据的情况下难以区分和准确识别。在这种情况下，物质鉴定专家算法（EASI）提供了优于传统方法的分类方法。利用来自十个实验室的 76 种芬太尼的 57,000 份重复电子电离质谱数据库，对三组具有挑战性的异构体进行了详细研究。为了最大限度地提高检测限，只考虑了 20 个最丰富的离子。在每种情况下，来自一个实验室的 50% 的数据作为训练集。使用 EASI 方法，已知阳性物的测量丰度与模型丰度之间的平均绝对残差比共识方法小五倍，共识方法使用训练集的平均值作为示范光谱，所有查询光谱都与之进行比较。在假阳性为零的保守阈值下，EASI 从两种最接近的异构体中识别出异戊酰芬太尼的准确率为 96.7%，比共识方法高出 10%。相关的阳性似然比从共识方法的 366 增加到 EASI 的 4,200 以上。在将异戊酰基芬太尼光谱与其他 72 种芬太尼进行鉴别时，EASI 提供了无差错的结果，其阳性似然比超过了 50,000 。在所有 9 种芬太尼中，EASI 的表现均优于共识方法和使用马哈拉诺比距离（Mahalanobis distance）作为识别异常值的指标的方法。在没有保留时间信息的情况下，EASI 提高了药物鉴定的可信度，实现了实验室之间的鉴定，并减少了获取标准品相关光谱的需要。

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引用次数: 0

Isotope fractionation during synthesis of methamphetamine from propiophenone, NaNO2 and dimethyl carbonate

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-04-09 DOI: 10.1016/j.forc.2025.100661

Brendan M. Miller , James F. Carter , Sarah L. Cresswell , Wendy A. Loughlin , Peter N. Culshaw

Ephedrine remains a key precursor in the production of methamphetamine. A novel ephedrine-based route to methamphetamine involved the nitrosation of propiophenone to α-isonitrosopropiophenone, followed by catalytic hydrogenation to phenylpropanolamine (± − norephedrine). Cyclization-methylation of phenylpropanolamine to 3,4-dimethyl-5-phenyl-2-oxazolidinone using dimethyl carbonate, followed by basic hydrolysis or catalytic hydrogenolysis formed ephedrine or methamphetamine, respectively.

An investigation into the stable isotope fractionation during the synthesis of methamphetamine from propiophenone, NaNO₂ and dimethyl carbonate was performed using isotope ratio mass spectrometry. A negative isotopic shift was observed for δ¹⁵N upon nitrosation of propiophenone to α-isonitrosopropiophenone, and a negative isotopic shift for δ²H during catalytic hydrogenation of α-isonitrosopropiophenone to phenylpropanolamine. Minimal change in δ¹³C was observed throughout the reaction until the methylation step with dimethyl carbonate, where a negative isotopic shift was observed.

The δ¹³C values for the methamphetamine presented in a similar range to methamphetamine reported in previous work where the norephedrine/norpseudoephedrine was prepared via different starting materials (benzaldehyde and nitroethane), confirming that similar δ¹³C values will result from fractionation during methylation with dimethyl carbonate regardless of the origin of the norephedrine/norpseudoephedrine. Chiral analysis confirmed methamphetamine to be racemic.

麻黄碱仍然是生产甲基苯丙胺的关键前体。以麻黄碱为基础的新型甲基苯丙胺生产工艺包括将苯丙酮亚硝化为 α-异亚硝基苯丙酮，然后催化加氢生成苯丙羟胺（± - 去甲麻黄碱）。使用碳酸二甲酯将苯丙羟胺环化-甲基化为 3,4-二甲基-5-苯基-2-恶唑烷酮，然后进行碱水解或催化氢化，分别生成麻黄碱或甲基苯丙胺。在将苯丙酮硝化成 α-异硝基苯丙酮的过程中，观察到 δ15N 发生了负同位素移动，在将α-异硝基苯丙酮催化氢化成苯丙羟胺的过程中，观察到 δ2H 发生了负同位素移动。在整个反应过程中，δ13C 的变化极小，直到与碳酸二甲酯发生甲基化反应时，才观察到负同位素位移。甲基苯丙胺的δ13C值与之前工作中报告的甲基苯丙胺的δ13C值范围相似，在之前的工作中，去甲麻黄碱/去甲伪麻黄碱是通过不同的起始原料（苯甲醛和硝基乙烷）制备的。手性分析证实甲基苯丙胺是外消旋的。

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引用次数: 0

Rescuing fluorescence with steric hindrance: Perylene diimide based powder for latent fingerprint imaging

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-04-08 DOI: 10.1016/j.forc.2025.100662

Rajdeep Kaur, Navjot Kaur, Prabhpreet Singh

We reported sterically crowded perylene diimide for rescuing its solid-state fluorescence through functionalization with bulkier hydroxyphenyl benzothiazole (PH2). The PH2 has (i) λ_max.at 620 nm; (ii) 28.8 % solid-state quantum yield and (iii) 100 % red colour purity calculated from CIE plot. PH2 adsorbed on silica nanoparticles was utilized as a fluorescent powder for the visualization of latent fingerprints on different porous, non-porous and curved surfaces using powder-dusting methods. The LFPs were subjected to laboratory conditions simulating those in the field such as aging, temperature, UV light and humidity and we successfully demonstrated the applicability of PH2-SiO₂ powder for the development and visualization of ridge pattern from these degraded LFPs. We also aimed to recover LFPs from physical evidence by developing the LFPs with PH2-SiO₂ followed by lifting of fingerprints using adhesive tape.

引用次数: 0

A UHPLC-(ESI)MS/MS method for the determination of the psychedelic secondary metabolite mescaline in San Pedro (Trichocereus spp.) and its applicability for screening mescaline in other cacti varieties.

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-03-24 DOI: 10.1016/j.forc.2025.100659

Pragna Gaur , Liam Engel , Damian Robert Hall , Cheang Khoo , Jerome Sarris , Daniel Perkins , Chun Guang Li , Mitchell Low

Commencements of clinical trials of psychedelic therapies for intractable forms of mental illnesses have drawn increased public attention to plants containing psychedelic substances. Whilst the psychoactive alkaloid mescaline has limited clinical trials, the San Pedro (Trichocereus spp.) cacti from which it is found have a long history of Indigenous medical and spiritual use. Traditional use remains licit in some jurisdictions, as supervised psychedelic dosage is typically regarded as tolerable with reports of only mild intoxications and few persisting negative psychological effects. However, mescaline concentration in ornamental San Pedro is highly variable, introducing risk of unintentional low or high dosage if misdirected for illicit use. This paper reports a validated UHPLC-(ESI)MS/MS method for the convenient and rapid quantification of mescaline in San Pedro, and for screening twelve potentially untested cacti. Preliminary results indicated that there may be higher amounts of mescaline in the chlorenchyma than the parenchyma of San Pedro. While six cacti lacked detectable mescaline, our screening enabled the first quantifications of mescaline in two varieties of Echinopsis subdenudata from 36 μg g⁻¹ to 2.45 mg g⁻¹. Chemotaxonomically, this amount of mescaline in a species from the traditional Echinopsis genus further suggests that the Trichocereus genus is not distinct and may support their contested combination into a single genus. Forensically, the identification of a popular ornamental cactus that was previously not known to contain mescaline demonstrates the need for routine screening of other cacti for the forensic sciences to remain ahead of emerging trends in psychedelic drug use.

迷幻疗法治疗顽固性精神疾病的临床试验开始后，含有迷幻物质的植物引起了公众越来越多的关注。虽然精神活性生物碱麦司卡林的临床试验有限，但圣佩德罗仙人掌（Trichocereus spp.）在一些司法管辖区，传统使用仍然是合法的，因为监管下的迷幻剂剂量通常被认为是可以承受的，只有轻微中毒的报告，很少有持续的负面心理影响。不过，观赏圣佩德罗中的麦司卡林浓度变化很大，如果被误导用于非法用途，就有可能无意中摄入过少或过多的剂量。本文报告了一种经过验证的超高效液相色谱-(ESI)质谱/质谱（UHPLC-(ESI)MS/MS）方法，用于方便、快速地定量检测圣佩德罗中的麦司卡林，并筛选 12 种可能未经检测的仙人掌。初步结果表明，圣佩德罗仙人掌软骨中的麦司卡林含量可能高于实质中的含量。虽然有六种仙人掌无法检测到麦司卡林，但我们的筛选工作首次对两个品种的 Echinopsis subdenudata 中的麦司卡林进行了定量，含量从 36 μg g-1 到 2.45 mg g-1。从化学分类学的角度来看，在一个传统的棘属物种中发现如此多的麦角碱，进一步表明三色堇属并不独特，并可能支持将它们合并为一个属的争议。从法医学角度来看，鉴定出一种以前不知道含有麦司卡林的流行观赏仙人掌表明，法医学需要对其他仙人掌进行例行筛查，以保持对迷幻药使用新趋势的领先地位。

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引用次数: 0

Incorporating organic gunshot residue into the forensic workflow: A study of preservation and stability of the pGSR and OGSR

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-03-22 DOI: 10.1016/j.forc.2025.100651

Kourtney A. Dalzell , Thomas Ledergerber , Tatiana Trejos , Luis E. Arroyo

In recent years, trace evidence examiners started to assess the value of incorporating two complementing analytical measurements: primer residue (pGSR) and organic gunshot residue (OGSR) data, aiming to strengthen firearms-related investigations. Still, there is a need to understand the cost-benefit of any method's modification for collecting, analyzing, and interpreting the combined information. This study aims to answer practical questions concerning optimal storage conditions for OGSR and pGSR, the feasibility of sequential analysis on the same sample, and whether pGSR or OGSR should be analyzed first. Samples were collected from shooters (n = 128) using a standard carbon adhesive stub. The stability of OGSR and pGSR was evaluated at the time elapsed from collection at the scene until analysis at the laboratory (1, 2 days, 1, 2 weeks, and 1, 2, 6 months) and storage conditions (room temperature or freezer). The experimental design includes the effect of the analysis sequence by either liquid chromatography-mass spectrometry (LC-MS/MS) and scanning electron microscopy energy dispersive X-ray spectrometry (SEM-EDS) on the detection rates. The results indicate a multi-testing approach does not compromise the integrity of pGSR or OGSR evidence when following appropriate protocols. The detection of OGSR and pGSR is not significantly different at the studied storage conditions or times when samples are preserved in sealed SEM stubs. These findings may alleviate some concerns regarding the feasibility of conducting an OGSR examination on samples that cannot be submitted to the laboratory immediately after collection and assist agencies in establishing preservation, storage, and acceptance criteria for future adoption.

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引用次数: 0

Extraction approaches for A-230, A-234, VX, and sarin nerve agents from surface coatings

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-03-22 DOI: 10.1016/j.forc.2025.100658

Tomáš Rozsypal

Nerve agents are among the most hazardous chemical warfare agents (CWAs) due to their extreme toxicity. This study optimized methods for extracting CWAs (A-230, A-234, VX, and sarin) from surface coatings, a common but chemically complex matrix in urban environments. Four types of coatings (nitrocellulose, polyurethane, acrylic, and alkyd) were tested using bulk, wipe, and scrape extraction approaches with various solvents. Versatile methods were successfully developed for all four analytes across all four matrices, and recoveries were also determined for additional CWAs (soman, cyclosarin, and sulfur mustard). Bulk extraction consistently achieved the highest recoveries, while wipe extraction offered a practical alternative with slightly reduced efficiency. Scrape extraction exhibited high variability and was unsuitable for volatile compounds like sarin. The methods were evaluated using gas chromatography with flame ionization detection, demonstrating robust analytical performance, including high sensitivity, precision, minimized matrix effects, and validated accuracy through spiking recoveries. Persistence studies revealed slow dissipation rates in surface coatings, underscoring their forensic potential when other matrices yield only degradation products. A-230 and A-234 were detectable in all coatings for up to 56 days, whereas sarin dissipated rapidly, especially in acrylic paint. VX remained primarily in surface layers due to its high viscosity and limited diffusion. These findings highlight the importance of tailoring extraction methods to specific matrices and agents. Coatings, with their prolonged retention of CWAs, not only provide significant forensic value but also emphasize the need for targeted decontamination strategies to mitigate environmental and human health risks.

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引用次数: 0

Analysis of substituted Cathinones and fentanyl analogs by gas chromatography-infrared spectroscopy (GC-IRD) using nitrogen carrier gas

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-03-18 DOI: 10.1016/j.forc.2025.100654

Marcus L. Warner

Substituted cathinones and fentanyl analogs that are positional isomers can produce similar mass spectra and retention times, which poses challenges for their identification. A gas chromatography-infrared spectroscopy (GC-IRD) method, developed using nitrogen as the carrier gas, was employed as a complimentary technique to gas chromatography-mass spectroscopy (GC–MS) for the accurate identification of positional isomers. Due to the global helium shortage and since Agilent helium (nitrogen switch) conservation modules were currently in use, nitrogen was selected and a novel method was developed for the analysis of controlled substances. A total method run time of 26 min for the analysis of 29 certified reference materials comprised of substituted cathinones and fentanyl analogs was achieved. A drug mixture was also analyzed to evaluate the resolution and retention time. Standards were prepared at concentrations of 100 μg/mL, 1 mg/mL and 2 mg/mL and analyzed over a 3-day period, where the 2 mg/mL concentrations of the standards were run in triplicate on day 1 and once on days 2 and 3. Twenty-seven of the standards were identified with a library match of 0.98 or higher for the 1 mg/mL concentration. Each standard experienced a retention time (RT) coefficient of variation (%CV) less than 3 %. For the drug mixture peak resolution exceeded 1.5 for each component. The GC-IRD validated method was found to be a suitable complementary analysis technique to GC–MS for analyzing substituted cathinones and fentanyl analogs, as demonstrated by the repeatable and reproducible RTs and library matches obtained during method validation.

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引用次数: 0

Chemical attribution signatures of nordiazepam for the determination of synthetic routes

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-03-13 DOI: 10.1016/j.forc.2025.100653

Meng Jin , Zixuan Zhang , Xiaogang Lu , Qian Wang , Runli Gao , Fengxia Sun , Hongmei Wang

The origin of illegal drugs is a crucial aspect of forensic work, which provides valuable information for combating and investigating the secret manufacture of drugs and medicines. This paper describes the use of comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS) to determine the Chemical Attribution Signatures (CASs) of nordiazepam, a key precursor of diazepam, for tracking the production of diazepam. Synthetic samples were identified and classified using GC × GC-TOFMS and chemometrics. Analysis samples (n = 12) were collected from two synthetic nordiazepam routes; resulting in the identification of 34 possible chemical attribution markers. The finding, combined with chemometric methods, enabled the establishment of a classification prediction model for route attribution. Through cross validation of the model, it has been proven that our model has good classification performance under controlled conditions and can effectively classify samples.

引用次数: 0

Evaluating machine learning methods on a large-scale of in silico fire debris data

IF 2.6 3区医学 Q2 CHEMISTRY, ANALYTICAL

Forensic Chemistry

Pub Date : 2025-03-12 DOI: 10.1016/j.forc.2025.100652

Larry Tang , Slun Booppasiri , Michael E. Sigman , Mary R. Williams

A large dataset of 240,000 fire debris samples have been generated in-silico using a data augmentation method at National Center for Forensic Science. The IS samples contain balanced data with 50 % samples having ignitable liquid residue and 50 % only having substrate components. In the big data era, this large dataset is useful for researchers to develop and implement their new machine learning methods. In this paper, we split the data into a training dataset and a test dataset. We then trained seven machine learning methods including logistic regression, least discriminant analysis, quadratic discriminant analysis, support vector machine, random forest, XGBoost, and neural network on an in-silico training dataset. The predictive accuracy and area under the ROC (AUC) of the models was evaluated and compared on both an in-silico test dataset and on an experimental fire debris dataset. In addition, we analyzed both TIS and TIC datasets. For the TIS dataset, neural network provides the highest AUC in both in-silico test and experimental fire debris dataset. Random forest shows the highest performance for the TIC dataset when we binned the retention index.

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引用次数: 0