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981.
Analytical method for the determination of strychnine in tissues by gas chromatography/mass spectrometry: two case reports 总被引:4,自引:0,他引:4
Marques EP Gil F Proen"ca P Monsanto P Oliveira MF Castanheira A Vieira DN 《Forensic science international》2000,110(2):145-152
This paper describes an analytical method for strychnine determination in biological samples by gas chromatography/mass spectrometry and their application in the investigation of two cases involving strychnine ingestion: A fatal case and a clinical one. The strychnine is isolated from biological samples using a liquid-liquid extraction procedure. The clean-up procedure is performed using an acid solution. Papaverine is used as internal standard in the quantification of strychnine. In the analysed specimens, the limits of quantification were 0.1 microg/ml or 0.1 microg/g. The recovery rate ranged from 75.0% to 98.7% and the coefficients of variation ranged from 4.8% to 10.5%. 相似文献
982.
An investigation of the rigor of interpretation rules for STRs derived from less than 100 pg of DNA 总被引:29,自引:0,他引:29
By increasing the PCR amplification regime to 34 cycles, we have demonstrated that it is possible routinely to analyse <100 pg DNA. The success rate was not improved (without impairing quality) by increasing cycle number further. Compared to amplification of 1 ng DNA at 28 cycles, it was shown that increased imbalance of heterozygotes occurred, along with an increase in the size (peak area) of stutters. The analysis of mixtures by peak area measurement becomes increasingly difficult as the sample size is reduced. Laboratory-based contamination cannot be completely avoided, even when analysis is carried out under stringent conditions of cleanliness. A set of guidelines that utilises duplication of results to interpret profiles originating from picogram levels of DNA is introduced. We demonstrate that the duplication guideline is robust by applying a statistical theory that models three key parameters - namely the incidence of allele drop-out, laboratory contamination and stutter. The advantage of the model is that the critical levels for each parameter can be calculated. This information may be used (for example) to determine levels of contamination that can be tolerated within the strategy employed. In addition we demonstrate that interpreting one banded loci, where allele dropout could have occurred, using LR=1/2f(a) was conservative provided that the band was low in peak area. Furthermore, we demonstrate that an apparent mis-match between crime-stain and a suspect DNA profile does not necessarily result in an exclusion. The method used is complex, yet can be converted into an expert system. We envisage this to be the next step. 相似文献
983.
Strömberg L Lundberg L Neumann H Bobon B Huizer H van der Stelt NW 《Forensic science international》2000,114(2):67-88
Three laboratories present a harmonised system for the retrospective comparison of south west Asian heroin. It consists of an improved gas chromatographic (GC) profiling method and a computerised data retrieval. The investigations of the GC were necessary with a view to improve the reproducibility of the system. The necessity of a strict quality control is emphasized. The peaks of the GC profile were investigated for abundance, intensity, GC behaviour (reproducibility) and correlations; 16 of them were selected for describing the heroin profile in the database. The results from intra-lab profile comparisons are reported. The reproducibility of the analysis was good and the variation between the samples was large, thus, allowing conclusions with a high degree of certainty. The criteria of similarity were defined. The system is successfully running in all three labs.In connection with inter-laboratory comparison, the aspects of method harmonisation and standardisation are discussed. It appeared that the GC method is a very subtile one, urging for a strict standardisation between the three labs. Despite a long cooperation between three well-equipped and experienced labs, a more or less serious loss of reproducibility was noticed in the inter-lab results in comparison with the intra-lab results. The loss could for the greater part be attributed to the (limits of the) GC technique; a number of compounds, necessary for making the discrimination between samples, showed difficult chromatographic behaviour, leading to insufficient inter-lab reproducibility. Using the actual variables, improvements in performance can hardly be expected in the near future. The loss of reproducibilty implies that the number of false positive matches in a database search increases. This may strongly reduce the value of a relatively large, international database. The study shows that so far, the best option for international comparison is the analysis in a central laboratory. The idea of local determination at a large number of national labs and the use of a common database is not a realistic aim for this type of analysis. 相似文献
984.
985.
986.
Siciliano C Costantinides F Bernasconi P Di Nunno N 《Journal of forensic sciences》2000,45(1):208-210
The authors describe an unusual case of suicide that required particular attention to establish whether the victim was murdered, was preparing a terrorist attack or had committed suicide. Examination of the corpse and the crime scene, as well as testimonies, led the authors to determine the real cause of death, namely, an unusual method of suicide. 相似文献
987.
Death of a worker occurred after ingestion of unknown amounts of Nicotiana glauca G leaves. The leaves were cooked after having been mistakenly considered to be spices of a type which grow in Thailand. After ingestion, two Thai workers collapsed, one with asystolia. Resuscitation efforts were successful only for one of the victims. A GC/MS method was used for the identification of anabasine as the main constituent in the leaves, food extract, blood, and the urine of the deceased. Lacking a standard, it was necessary to interpret the GC/MS spectrum to identify anabasine and establish its presence. 相似文献
988.
989.
990.
We performed an autopsy on a frozen newborn infant who was found in a freezer at -18 degrees C. After thawing, froth emerged from the nostrils and was present in the trachea. Sometimes froth may be seen in the air-passage in cases of strangulation and drowning. In our case, however, there was neither proof of asphyxia due to strangulation nor drowning. The existence of the froth indicates that the infant was probably in a state of respiratory distress before death. Histologic findings of the lung showed that the infant did not suffer from respiratory disorders such as respiratory distress syndrome. Karyopyknosis and vacuolation of the keratinocytes, shrinkage of the hepatocytes, dilatation of the sinusoid, spaces between heart muscle fibers and deep staining of the nuclei and hemolysis were characteristic in our case. This case shows that froth persists in the internal air-passage for a long time as a result of freezing. Moreover, the froth in the air-passage, along with the findings of the lungs, demonstrates that the newborn infant was born alive. 相似文献