Characterisation of gunshot residue from three ammunition types using suppressed anion exchange chromatography

Gunshot residue (GSR) is commonly analysed in forensic casework using either scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) or gas chromatography-mass spectrometry (GC-MS). Relatively little work has been reported on the post-discharge GSR content of non-metallic inorganic or low molecular weight organic anions to distinguish between different ammunition types. The development of an analytical method using suppressed micro-bore anion exchange chromatography (IC) is presented for the analysis of GSR. A hydroxide gradient was optimised for the separation of 19 forensically relevant organic and inorganic anions in <23min and sensitivities of the order of 0.12-3.52ng of anion detected for all species were achieved. Along with an optimised extraction procedure, this method was applied to the analysis of post-ignition residues from three selected ammunition types. By profiling and comparing the anionic content in each ammunition residue, the possibility to distinguish between each type using their anionic profiles and absolute weight is presented. The potential for interference is also discussed with respect to sample types which are typically problematic in the analysis of GSR using SEM-EDX and GC-MS. To the best of our knowledge this represents the first study on the analysis of inorganic anions in GSR using suppressed ion chromatography.     

The use of the likelihood ratio for evaluative and investigative purposes in comparative forensic handwriting examination

This paper extends previous research and discussion on the use of multivariate continuous data, which are about to become more prevalent in forensic science. As an illustrative example, attention is drawn here on the area of comparative handwriting examinations. Multivariate continuous data can be obtained in this field by analysing the contour shape of loop characters through Fourier analysis. This methodology, based on existing research in this area, allows one describe in detail the morphology of character contours throughout a set of variables. This paper uses data collected from female and male writers to conduct a comparative analysis of likelihood ratio based evidence assessment procedures in both, evaluative and investigative proceedings. While the use of likelihood ratios in the former situation is now rather well established (typically, in order to discriminate between propositions of authorship of a given individual versus another, unknown individual), focus on the investigative setting still remains rather beyond considerations in practice. This paper seeks to highlight that investigative settings, too, can represent an area of application for which the likelihood ratio can offer a logical support. As an example, the inference of gender of the writer of an incriminated handwritten text is forwarded, analysed and discussed in this paper. The more general viewpoint according to which likelihood ratio analyses can be helpful for investigative proceedings is supported here through various simulations. These offer a characterisation of the robustness of the proposed likelihood ratio methodology.     

Unexpected natural death secondary to intra-abdominal bleeding: report of one idiopathic spontaneous intraperitoneal hemorrhage case

A 39-year-old woman was found dead at home. She was single, foreign national, chronic alcoholic, and had given shelter to a compatriot for three days. This man found the deceased in her bed, after a night of heavy drinking. The emergency medical team observed numerous recent blue ecchymoses of the upper limbs. Because of the unclear circumstances, a medicolegal autopsy was ordered by the public prosecutor. Massive hemoperitoneum was diagnosed with no visible internal traumatic injury. Autopsy revealed hepatic and pancreatic abnormalities secondary to chronic alcoholism, which were confirmed by pathological study. The source of the hemoperitoneum was not identified despite careful visceral and vascular examination. The authors concluded that death was secondary to idiopathic spontaneous hemoperitoneum or abdominal apoplexy. The forensic literature on unexpected death due to massive nontraumatic intra-abdominal hemorrhage in association with liver cirrhosis is sparse, with only five cases reported, including the present case.     

Influence of CYP2D6 genotype on the disposition of the enantiomers of venlafaxine and its major metabolites in postmortem femoral blood

Venlafaxine (VEN) is an antidepressant drug mainly metabolized by the cytochrome P450 (CYP) enzyme CYP2D6 to the active metabolite O-desmethylvenlafaxine (ODV). VEN is also metabolized to N-desmetylvenlafaxine (NDV) via CYP3A4. ODV and NDV are further metabolized to N,O-didesmethylvenlafaxine (DDV). VEN is a racemic mixture of the S- and R-enantiomers and these have in vitro displayed different degrees of serotonin and noradrenaline reuptake inhibition. The aim of the study was to investigate if an enantioselective analysis of VEN and its metabolites, in combination with genotyping for CYP2D6, could assist in the interpretation of forensic toxicological results in cases with different causes of deaths. Concentrations of the enantiomers of VEN and metabolites were determined in femoral blood obtained from 56 autopsy cases with different causes of death. The drug analysis was done by liquid chromatography tandem mass spectrometry (LC/MS/MS) and the CYP2D6 genotyping by PCR and pyrosequencing. The mean (median) enantiomeric S/R ratios of VEN, ODV, NDV and DDV were 0.99 (0.91), 2.17 (0.93), 0.92 (0.86) and 1.08 (1.03), respectively. However, a substantial variation in the relationship between the S- and R-enantiomers of VEN and metabolites was evident (S/R ratios ranging from 0.23 to 17.6). In six cases, a low S/R VEN ratio (mean 0.5) was associated with a high S/R ODV ratio (mean 11.9). Genotyping showed that these individuals carried two inactive CYP2D6 genes indicating a poor metabolizer phenotype. From these data we conclude that enantioselective analysis of VEN and ODV can predict if a person is a poor metabolizer genotype/phenotype for CYP2D6. Knowledge of the relationship between the S- and R-enantiomers of this antidepressant drug and its active metabolite is also important since the enantiomers display different pharmacodynamic profiles.     

Raman spectroscopy and microspectrophotometry of reactive dyes on cotton fibres: Analysis and detection limits

A collaborative study on Raman spectroscopy and microspectrophotometry (MSP) was carried out by members of the ENFSI (European Network of Forensic Science Institutes) European Fibres Group (EFG) on different dyed cotton fabrics. The detection limits of the two methods were tested on two cotton sets with a dye concentration ranging from 0.5 to 0.005% (w/w). This survey shows that it is possible to detect the presence of dye in fibres with concentrations below that detectable by the traditional methods of light microscopy and microspectrophotometry (MSP). The MSP detection limit for the dyes used in this study was found to be a concentration of 0.5% (w/w). At this concentration, the fibres appear colourless with light microscopy. Raman spectroscopy clearly shows a higher potential to detect concentrations of dyes as low as 0.05% for the yellow dye RY145 and 0.005% for the blue dye RB221. This detection limit was found to depend both on the chemical composition of the dye itself and on the analytical conditions, particularly the laser wavelength. Furthermore, analysis of binary mixtures of dyes showed that while the minor dye was detected at 1.5% (w/w) (30% of the total dye concentration) using microspectrophotometry, it was detected at a level as low as 0.05% (w/w) (10% of the total dye concentration) using Raman spectroscopy. This work also highlights the importance of a flexible Raman instrument equipped with several lasers at different wavelengths for the analysis of dyed fibres. The operator and the set up of the analytical conditions are also of prime importance in order to obtain high quality spectra. Changing the laser wavelength is important to detect different dyes in a mixture.     

Clinical and forensic examinations of glycemic marker 1,5-anhydroglucitol by means of high performance liquid chromatography tandem mass spectrometry

Postmortem diagnosis of diabetes and a diabetic coma can be difficult because of the lack of characteristic morphological findings. 1,5-Anhydroglucitol (1,5-AG), the 1-deoxy form of glucose, competes with glucose for reabsorption in the kidneys. Therefore, diabetics with a permanent hyperglycemia show significantly lower serum concentrations of 1,5-AG than non-diabetics. A liquid chromatography-mass spectrometric method for the determination of 1,5-AG in serum and postmortem blood was developed and validated according to international guidelines. Linearity was given between 1μg/ml and 50μg/ml. Recovery rates ranged between 70.8% and 89.8%, the limit of quantification of the procedure was 0.20μg/ml, limit of quantification was 0.55μg/ml. Serum of 199 diabetics and 116 non-diabetics and femoral blood of 31 diabetic and 27 non-diabetic deceased was measured. Average concentrations were significantly (p<0.001) higher in non-diabetics compared to diabetics ante and postmortem. Seven of the diabetics may have died because of a hyperglycemic coma indicated by a sum formula of Traub>450mg/dl. 1,5-AG average concentrations in these deceased were not significantly different to diabetics which did not die because of a diabetic coma. Concentrations of 1,5-AG give a hint for not well controlled diabetes antemortem and postmortem and can be assumed as an additional and alternative information postmortem to the measurement of HbA1c or fructosamine.     

Fatal tolperisone poisoning: autopsy and toxicology findings in three suicide cases

Tolperisone (Mydocalm) is a centrally acting muscle relaxant with few sedative side effects that is used for the treatment of chronic pain conditions. We describe three cases of suicidal tolperisone poisoning in three healthy young subjects in the years 2006, 2008 and 2009. In all cases, macroscopic and microscopic autopsy findings did not reveal the cause of death. Systematic toxicological analysis (STA) including immunological tests, screening for volatile substances and blood, urine and gastric content screening by GC-MS and HPLC-DAD demonstrated the presence of tolperisone in all cases. In addition to tolperisone, only the analgesics paracetamol (acetaminophen), ibuprofen and naproxen could be detected. The blood ethanol concentrations were all lower than 0.10 g/kg. Tolperisone was extracted by liquid-liquid extraction using n-chlorobutane as the extraction solvent. The quantification was performed by GC-NPD analysis of blood, urine and gastric content. Tolperisone concentrations of 7.0 mg/l, 14 mg/l and 19 mg/l were found in the blood of the deceased. In the absence of other autopsy findings, the deaths in these three cases were finally explained as a result of lethal tolperisone ingestion. To the best of our knowledge, these three cases are the first reported cases of suicidal tolperisone poisonings.     

THCVA-A - a new additional marker for illegal cannabis consumption

The aim of the present investigations was to find markers for differentiating between the consumption of illegal cannabis products and legal medication containing fully synthetic Δ9-tetrahydrocannabinol (Δ9-THC), e.g., Marinol capsules. Δ9-Tetrahydrocannabinolic acid A (Δ9-THCA-A) and Δ9-tetrahydrocannabivarinic acid A (Δ9-THCVA-A) were taken into consideration for analysis, because these substances are the precursors of Δ9-THC and Δ9-tetrahydrocannabivarin (Δ9-THCV) in plant material of Cannabis sativa and are not contained in medical THC formulations. Whereas Δ9-THCA-A is an already well investigated substance, there is little analytical data on Δ9-THCVA-A. The reason for the presented investigations was a case in which a man was tested positive for Δ9-THC during a routine traffic control claiming that the positive serum sample resulted from the intake of a THC medication (Marinol) and not from consuming illegal cannabis products. Sample preparation consisted of a protein precipitation with acetonitrile. Analysis was carried out on a Thermo Fisher LCQ Deca ion trap LC-MS-MS-system using electron spray ionization (ESI) in negative mode. MS(2)- and MS(3)-full scan spectra were recorded for Δ9-THCA-A and Δ9-THCVA-A starting from [M-H](-). Reference spectra were obtained by measuring a Δ9-THCA-A reference solution and an ethanolic cannabis extract for Δ9-THCVA-A as there is no reference material for this cannabinoid available on the market yet. Main transitions for Δ9-THCA-A were m/z 357→313 and 339 in the MS(2)-spectrum and m/z 313→245 and 191 in the MS(3)-spectrum. Fragmentation pattern of Δ9-THCVA-A was identical with a difference of 28 amu less for the precursor ion as well as the fragments due to a shorter alkyl side chain in the molecule (MS(2): m/z 329→285 and 311; MS(3): m/z 285→217 and 163). The two plant cannabinoids Δ9-THCA-A and Δ9-THCVA-A could be detected in the serum sample by LC-MS-MS which proved the intake of illegal cannabis products derived from plant material of C. sativa in the described case.