Forensic Chemistry最新文献

Marijuana and hemp are different cultivars of the species, Cannabis sativa. Trichomes within these genetically distinct forms result in different chemical constituents within the plant matrix. While drug-type cannabis yields higher total Δ9-THC concentrations, industrial or consumer-based hemp products are typically rich in cannabidiol or CBD-rich. Regulatory changes following the passage of agricultural legislation in the United States defines hemp as C. sativa containing no more than 0.3 % Δ9-THC on a dry weight basis. This threshold, which effectively differentiates legal hemp from illegal marijuana, presents a challenge to operational forensic laboratories. In this report we describe a decision-point assay to differentiate hemp from marijuana using a 1 % threshold. Methanolic extracts of C. sativa were analyzed using gas chromatography-mass spectrometry (GC–MS) using a deuterated analog (Δ9-THC-D3). Synchronous selected ion monitoring (SIM) and full scan acquisition was used for targeted analysis of Δ9-THC at the decision-point. Assay performance was evaluated in terms of limit of detection, linearity, carryover, selectivity, precision, accuracy and extract stability. Two analytical approaches are presented. Extraction efficiencies of Δ9-THC from plant matrix were 80–92 %, and decarboxylation of Δ9-tetrahydrocannabinolic acid (THCA) was 67 %. Interferences arising from the cyclization of CBD to produce Δ9-THC in the GC inlet were addressed using concentrations in excess of those typically encountered in plant samples. Accuracy was established across the specified range of the assay using known reference materials containing 0.12 to 10.1 % Δ9-THC. No false positive or negative results were identified (n = 140) using both analytical approaches.

Methamphetamine is produced using various routes from two predominant precursors, ephedrine/pseudoephedrine or phenyl-2-propanone (P2P). The multitude of synthetic routes results in many possible impurities (by-products or intermediates). Impurity profiling of methamphetamine by gas chromatography-mass spectrometry (GC–MS) is an important tool for the forensic chemist and investigators to assist in identification of the synthetic pathway and linking seizures. With the emergence of alternative routes, continued research into impurity profiles is important. One such alternative route is an ephedrine/pseudoephedrine-based pathway using the precursors typically associated with the phenyl-2-propanone (P2P) route, benzaldehyde and nitroethane. Benzaldehyde and nitroethane were condensed to form 2-nitro-1-phenyl-1-propanol. Subsequent reduction led to the corresponding 2-amino-1-phenyl-1-propanol. Cyclization-methylation with dimethyl carbonate to 3,4-dimethyl-5-phenyl-2-oxazolidinone, followed by catalytic hydrogenolysis or basic hydrolysis formed methamphetamine and ephedrine/pseudoephedrine, respectively. This paper presents the impurity profile of the alternative route. The conditions for the reduction of the intermediate 2-nitro-1-phenyl-1-propanol to 2-amino-1-phenyl-1-propanol was found to influence the by-products observed in the methamphetamine product. Notable by-products were amphetamine, N-ethylamphetamine and N-hydroxymethamphetamine.

Interest in facile and sensitive methods for cyanide detection is related to the extreme cyanide toxicity and its importance in forensic toxicology. In this research a novel application of Ion Mobility Spectrometry (IMS) was demonstrated for rapid determination of cyanide poisoning in postmortem toxicology. In addition, a simple method for the sample preparation was applied based on the analyte (cyanide anion) transfer as HCN to the headspace and direct injection to IMS. The method showed a linear dynamic range of 50–2000 µg/L with R² > 0.99, a high sensitivity (LOD of 20.4 µg/L and LOQ of 68.1 µg/L). Good repeatability (intra- and inter-assays, CV < 15 %) and excellent extraction recovery (82 -94 %) were obtained. After validation, the method was applied in the analysis of postmortem human blood samples in forensic cases. In all samples, the cyanide was promptly quantified.

Hypochlorite bleach is an easily accessible, commonly used cleaning product. Methamphetamine and ephedrine hydrochloride react rapidly with 3.5 g/L (1:8 dilution of a commercial household bleach) and 21 g/L (2:1 dilution) solutions of sodium hypochlorite bleach in water, with each reaction being complete within 5 min of mixing. The major methamphetamine reaction product was identified as N-chloromethamphetamine which was reliably quantified by dechlorination using a sulfite quench prior to sample extraction and analysis by gas chromatography – mass spectrometry (GC–MS). The initial product from ephedrine was benzaldehyde, and this then formed benzoic acid as a second-generation product in the 3.5 g/L sodium hypochlorite bleach solution.

N-Chloromethamphetamine was observed to persist in solution for several hours with minor formation of benzaldehyde and N-chloro-1-phenylpropan-2-imine, a proposed second-generation product from N-chloromethamphetamine, also detected. Assessment of further N-chloramine reaction products will aid in our ability to estimate exposure risks to those attempting drug remediation using hypochlorite bleach. These observed products can also be used as potential forensic markers of the use of a property for illicit activity if bleach has been used in an attempt to decontaminate the location.

Phenibut is an anxiolytic and nootropic substance with GABA-mimetic properties. Phenibut is readily available on the Internet and is not a controlled substance under the Controlled Substances Act in the United States. Adverse effects of phenibut include tremors, decreased appetite, agitation, and insomnia. In this study, a sample was obtained from a tobacco shop in Richmond, Virginia. The product was labeled as “Moon Water” and contained a yellow liquid. The Moon Water sample label content promotes energy and focus properties. Labeled ingredients included filtered water, fructose, citric acid, <2 % ascorbic acid, maltodextrin, sodium acid pyrophosphate, sodium citrate, magnesium oxide, calcium fumarate, artificial color, and tocopherol.

The Moon Water sample was screened using Direct Analysis in Real Time-Mass Spectrometry (DART-MS) and Gas Chromatography-Mass Spectrometry (GC–MS) for the detection of active compounds not described in the label. Phenibut and other substances absent from the label such as caffeine were detected with DART-MS analysis. Their presence was confirmed using GC–MS.

Phenibut exhibits agonism at the GABA receptors, specifically the GABA_B receptor. High doses of phenibut can result in combativeness, delirium, and aggression. Phenibut usage can result in dependence and subsequent withdrawal, with effects ranging from anger, irritability, insomnia, decreased appetite, and heart palpitations. This work highlights the need for proper regulation of commercially available products, specifically those sold in smoke and tobacco shops. The presence of psychoactive substances that are not labeled on the product are a public health concern and an utmost risk to the consumer.

Fentanyl and fentanyl analogs are key figures at the center of the ongoing opioid epidemic in the United States. Currently, gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) instrumentation is one of the main analytical tools used for the identification of fentanyl analogs in forensic laboratories. However, the resulting retention times and EI mass spectra for many fentanyl analogs are quite similar given that there are only subtle differences in their structures. This research investigates the effect of substitution location on fentanyl analog identification using GC-EI-MS and the National Institute of Standards and Technology (NIST) Simple Similarity Search (SSS) and Hybrid Similarity Search (HSS) algorithms through the analysis of a series of 11 methyl-substituted fentanyl analogs.

The 95% confidence interval retention times for each isomer were never more than ±0.009 min and a statistically significant (p < 0.001) difference was observed for all pairwise comparisons. Careful examination of the EI mass spectra revealed several general trends about the influence of substitution location on the observed EI mass spectra. The combination of unique fragmentation patterns, formed through shifts in m/z values due to the location of substitution, and the retention time enabled the identification of the 11 methyl-substituted fentanyl analogs analyzed in this study. The SSS was able to correctly identify all methyl-substituted fentanyl analogs within the top five hits for compounds that were present in the library. In comparison, the HSS was used to identify compounds absent from the mass spectral libraries and provided drastically different results depending on the location of substitution.

The use of Oleoresin Capsicum (OC)-based sprays has been reported as non-lethal self-defense tools in Europe since the 1950 s. Stinging pepper sprays may be very useful tool for self-defense in case of aggression, but they can turn into instruments of panic production with fatal outcomes, as demonstrated by what happened in the deadly Turin soccer stampede in 2017 or in Corinaldo (Ancona, Italy) nightclub in 2018.

The aim of the present work was the development and validation of an analytical method for the determination of the two most common capsaicinoids contained in OC-sprays at crime scenes. A simple and effective method for the extraction of capsaicinoids from commercial swabs, has been developed. Sample clean-up was carried out by μ-SPE, in order to reduce matrix effect. Qualitative and quantitative analysis was carried out by means of UHPLC-HRMS/MS.

The validated method was applied to the investigations related to the Corinaldo nightclub case, where a OC-spray was suspected of having created panic among the crowd, causing six dead and dozens hurt. A total number of 118 samples were collected from disco surfaces, including floors and balustrades, using swabs. The samples were treated and analysed with a validated method in order to identify and quantify the presence of capsaicinoids. Thanks to the large number of samples, it was possible to draw a concentration map of the analytes of interest within the disco, making possible to identify the room area from which the spray delivery started.

Sexual lubricants are likely to be encountered at crime scenes due to the wide availability and variability of the products. These lubricants found in sexual assault cases may help supplement biological evidence or be the primary evidence where there is a lack of DNA evidence. The discrimination of sexual lubricants will help assess the potential contact between the victim and the suspect. In this study, an analysis of a total of 43 products of condom lubricants, bottled sexual lubricants, and personal hygiene products was carried out to evaluate their variability and discrimination potential. ATR-FTIR spectroscopy was used to analyze the samples, and the spectra were then visually examined and interpreted using chemometrics. Visual analysis revealed three different groupings of the samples based on their chemical profile. Chemometric classification was done using LDA and SVM in a two-stage classification process: identification of the type of product and a brand-level classification. The combination of LDA and SVM helped to discriminate the samples further in an objective manner. In stage 1 classification, SVM showed 100% classification accuracy. In the second stage, 70.83% classification accuracy was achieved using SVM for condom samples. Whereas, 96.15% classification was achieved using LDA for bottled lubricants. Evaluation of how these products can be linked to their sources is also needed when they are encountered as traces in various substrates. A substrate study was conducted while considering two factors: environment and time. The findings indicated that the type of substrate, lubricant, and storage period may affect the discrimination.