The zinc test as an alternative for acid phosphatase spot tests in the primary identification of seminal traces

The value of the acid phosphatase spot test in the primary visualization and identification of seminal traces is hampered by the sensitiveness of the enzyme to biodegradation. An alternative spot test is proposed, based on the high concentration of the more stable zinc metal in seminal plasma. The proposed zinc spot test is simple and suitable for on site investigation. Although the sensitivity in fresh stains is lower than that of the acid phosphatase spot test, this is largely compensated by the lower sensitiveness to biodegradation. The specificity for semen is higher than that of the acid phosphatase spot test. In vaginal swabs it was nevertheless seen, that samples should be taken within 24 h after alleged sexual assault to give reliable results.     

The rapid determination of cocaine and other local anesthetics using field tests and chromatography

The application of field tests and chromatography to the detection of cocaine and some other local anesthetics that have been used to adulterate cocaine is described. Initial screening of samples by field tests, followed by concurrent TLC and GC, enables rapid identification of these compounds to be achieved. In particular, the use of flow-programmed GC shortens the time for analysis compared with conventional GC and requires negligible equilibration time between consecutive runs [12]. The method gives reliable quantitative data.     

Comparison of gunshot wounds and field-tipped arrow wounds using morphological criteria and chemical spot tests

Arrow wounds represent an unusual class of wounds rarely seen by most death investigators. Although the edged, broadhead-tipped arrow produces a wound usually characteristic of archery/crossbow weapons, the plain, field-tipped arrow wound can be confused with gunshot injuries in those cases in which powder residue or firearm projectiles or fragments or both are not recovered. We present a case of a deer carcass with a wound of uncertain firearm or archery origin which initiated a comparison of firearm wounds and archery wounds on fresh road-killed deer. We found the following features to be valuable in the differentiation of gunshot wounds and field-tipped archery wounds: First, the majority of the gunshot wounds (but none of the arrow wounds) had identifiable, macroscopic, wipe-off material and chemically identifiable wipe-off residue by spot test. Second, the archery wound defects had very inconspicuous abrasion rings as compared to the often prominent abrasion rings of gunshot wounds. Third, the actual central defect in the archery wounds was more likely to be oblong or slit-like compared to the gunshot wound defects, which were more likely to be round.     

Highly polymorphic minisatellite DNA probes. Further evaluation for individual identification and paternity testing

Reliable and reproducible protocols have been developed for the routine DNA fingerprinting of individuals using the highly polymorphic minisatellite DNA probes 33.15 and 33.6. Comparison of DNA fingerprinting from 50 individuals has generated further data on the level of band sharing in the DNA fingerprints of unrelated individuals, as well as the number of bands scorable in individuals. These results are consistent with previous studies. The occurrence of mutant bands in offspring has been examined in over 100 families. Further support is presented for the Mendelian inheritance of minisatellite loci and for lack of significant allelism and linkage between different variable DNA fragments detected in a human DNA fingerprint.     

PCR扩增体系的体积减少对DNA分析的影响

目的探讨PCR扩增体系的体积减少对DNA分析的影响。方法4份样品采用ProfilerPlus试剂盒,在同样条件下,对50μl、25μl、12.5μl、6.25μl四种体积的体系进行扩增,扩增产物分别经ABIPRISMTM310型基因分析仪、ABIPRISMTM377型测序仪、ABIPRISMTM3100型基因分析仪电泳,并经GeneScan3.1基因扫描软件和Genotyper2.5分析软件分析得到实验结果。结果小体积的扩增体系容易出现等位基因的丢失、额外等位基因的产生等现象。结论在检材情况较差时,应该慎用小体积的扩增体系。     

Comparative study of the sensitivity and specificity of the zinc and acid phosphatase spot tests for the detection of seminal stains

The sensitivity and specificity of a zinc spot test for the detection of semen were compared with those of an acid phosphatase detection method. As screening techniques both tests were found to be very sensitive, but the zinc test was more specific and was more reliable in older and especially in deteriorated specimens. It is concluded that the zinc spot test deserves at least the same place as the acid phosphatase test in the primary investigation of suspected semen stains and might well be the test of choice in older and poorly preserved stains.     

Clarifying the complex chemistry of cobalt(II) thiocyanate-based tests for cocaine using single-crystal X-ray diffraction and spectroscopic techniques

Cobalt(II) thiocyanate-based tests are routinely used to screen cocaine products, with the formation of a blue species interpreted as a positive response. An array of other organic bases has been identified as false positives – including well-documented cocaine product adulterant lidocaine and its salt. False positives prompt continued test development, though improvements are hindered by unresolved product structures and reaction pathways. Toward greater clarity, cobalt(II) thiocyanate reactions with cocaine hydrochloride, along with lidocaine and its salt, were investigated using multiple analytical techniques. Reactions involving cocaine hydrochloride yielded glassy, amorphous blue material while reactions of lidocaine hydrochloride monohydrate produced larger, needle-like crystals whose structure was determined via single-crystal X-ray diffraction to be an ion pair (Hlidocaine⁺)₂([Co(SCN)₄]²⁻)·H₂O. While the blue precipitate isolated from reactions involving cocaine hydrochloride was unsuitable for crystallographic structure determination, comparative ultraviolet–visible, attenuated total reflectance infrared, and Raman spectroscopic analysis – along with elemental analysis – supports that this solid is comprised of a comparable ion pair (Hcocaine⁺)₂[Co(SCN)₄]²⁻. Pink crystals isolated from lidocaine reaction vessels were identified as coordination compounds cis-[CoL₂(SCN)₂] and trans-[CoL₂(SCN)₂] where L = lidocaine, while pink crystals from both cocaine hydrochloride and lidocaine hydrochloride monohydrate reaction vessels were the coordination polymer trans-[Co(H₂O)₂(SCN)₂]·H₂O. The results presented herein enable reaction optimization to favor a desired product, whether ion pair or coordination species.     

A sequence of tests of minute human blood stains for human origin identification and ABO blood grouping

A series of examinations is presented for human origin identification and ABO blood grouping of doubtful minute human blood stains. A blood-stained thread (0.5 cm in length) was first tested to identify human origin by microprecipitation method and then the ABO blood type was determined by both a modified absorption-elution test and a modified mixed agglutination. In the continuous tests, the maximum limits of positive reactions of the microprecipitation method, the modified absorption-elution test, and the modified mixed agglutination were 1:640, 1:160, and 1:2,560 diluted blood, respectively. A and B agglutinogens were more sensitively determined than H agglutinogen. Hemagglutinogens of blood stains on cotton threads were more easily detected than those of polyester ones.     

Cocaine profiling. A method of comparative substance studies of illegal cocaine samples]

Illegal cocaine were extracted in acidic medium. The extracts contain significant amounts of truxinic and truxillic acids. Successful comparism of cocaine out of different sources can be achieved by chromatographing trimethylsilyl- or dimethyl-t.-butylsilyderivates. The application of the method Ist limited by the purity of the samples.     

Hair analysis for cocaine: Factors in laboratory contamination studies and their relevance to proficiency sample preparation and hair testing practices

Hair samples were contaminated by rubbing with cocaine (COC) followed by sweat application, multiple shampoo treatments and storage. The samples were then washed with isopropanol for 15 min, followed by sequential aqueous washes totaling 3.5 h. The amount of drug in the last wash was used to calculate a wash criterion to determine whether samples were positive due to use or contamination. Analyses of cocaine and metabolites were done by LC/MS/MS. These procedures were applied to samples produced by a U.S. government-sponsored cooperative study, in which this laboratory participated, and to samples in a parallel in-house study. All contaminated samples in both studies were correctly identified as contaminated by cutoff, benzoylecgonine (BE) presence, BE ratio, and/or the wash criterion. A method for determining hair porosity was applied to samples in both studies, and porosity characteristics of hair are discussed as they relate to experimental and real-world contamination of hair, preparation of proficiency survey samples, and analysis of unknown hair samples.     

Hair analysis for cocaine: factors in laboratory contamination studies and their relevance to proficiency sample preparation and hair testing practices

Since the introduction in 2001 of a urine-based detection method for recombinant erythropoietin (rHuEPO), transfusion-doping practices have regained interest. To address this problem, an efficient antidoping test designed to obtain direct proof of allogeneic blood transfusion was developed and validated. This test, based on flow cytometry analysis of red blood cell (RBCs) phenotypes, was used to determine the absence or the presence of numerous RBCs populations in a blood sample. A such, it may constitute a direct proof of an abnormal blood population resulting from homologous transfusion. Single-blind and single-site studies were carried out to validate this method as a forensic quality standard analysis and to allow objective interpretation of real cases. The analysis of 140 blood samples containing different percentages (0-5%) of a minor RBCs population were carried on by four independent analysts. Robustness, sensitivity, specificity, precision and stability were assessed. ISO-accredited controls samples were used to demonstrate that the method was robust, stable and precise. No false positive results were observed, resulting in a 100% specificity of the method. Most samples containing a 1.5% minor RBCs population were unambiguously detected, yielding a 78.1% sensitivity. These samples mimicked blood collected from an athlete 3 months after a homologous blood transfusion event where 10% of the total RBCs present in the recipient originated in the donor. The observed false negative results could be explained by differences in antigen expression between the donor and the recipient. False negatives were more numerous with smaller minor RBCs populations. The method described here fulfils the ISO-17025 accreditation and validation requirements. The controls and the methodology are solid enough to determine with certainty whether a sample contains one or more RBCs populations. This variable is currently the best indicator for homologous blood transfusion doping.     

A multilevel analysis of the effect of cocaine price on cocaine use among arrestees

Using data drawn from the Arrestee Drug Abuse Monitoring Program, from the Drug Enforcement Administration's System to Retrieve Information from Drug Evidence, and from the 1990 Census, this study examined whether an arrestee's probability of testing positive for cocaine use varied across aggregate levels of cocaine price. Results from a Hierarchical Generalized Linear Modeling analysis revealed that in cities where the price of cocaine was relatively high, arrestees had a lower probability of testing positive for cocaine use. Specifically, a 10 percent increase in the price of cocaine was associated with a 3 percent decrease in the odds that an arrestee would test positive for cocaine use. Findings also showed that individuals arrested for income-generating crimes did not have a higher probability of testing positive for cocaine when the price of cocaine was relatively high. Thus, it appeared that higher cocaine prices were not inducing users to amplify their criminal activity in order to finance a more costly drug addiction. Finally, results failed to furnish support for the hypothesis that individuals substituted opiates or marijuana when cocaine became more expensive.     

Validity testing of commercial urine cocaine metabolite assays: III. Evaluation of an enzyme-linked immunosorbent assay (ELISA) for detection of cocaine and cocaine metabolite

A validity assessment study was performed on the Genetic Diagnostic Enzyme Immunoassay test kit, a new enzyme-linked immunosorbent assay (GDC ELISA) for detection of cocaine and cocaine metabolite in urine. A set of 290 urine specimens, comprised of clinical cocaine urines collected from 5 male subjects who had received single doses of intravenous cocaine, drug-free urines spiked with cocaine, cocaine metabolites, cocaine isomers, and other drugs of abuse, were assayed by GDC ELISA. The results were compared with results by gas chromatography/mass spectrometry (GC/MS) assay for benzoylecgonine. Concordance was high between the GDC ELISA assay and GC/MS and with results reported earlier for other commercial assays. Detection times and specificity of the GDC ELISA antibody were most similar to those of the Abuscreen radioimmunoassay for cocaine metabolite. Overall, the assay produced no false negative or false positive results and appeared to be a reliable screening test for detection of cocaine and benzoylecgonine in human urine.     

Segmental hair analysis for cocaine and heroin abuse determination

Segmental hair analysis was performed to obtain information about the history of drug abuse of subjects in a rehabilitation programme. The analytical data from hair samples were correlated, when possible, with urine analysis and to toxicological anamnesis. Toxicological analysis of hair seems to be a valid tool in this specific field.     

Headspace profiling of cocaine samples for intelligence purposes

A method for determination of residual solvents in illicit hydrochloride cocaine samples using static headspace-gas chromatography (HS-GC) associated with a storage computerized procedure is described for the profiling and comparison of seizures. The system involves a gas chromatographic separation of 18 occluded solvents followed by fully automatic data analysis and transfer to a PHP/MySQL database. First, a fractional factorial design was used to evaluate the main effects of some critical method parameters (salt choice, vial agitation intensity, oven temperature, pressurization and loop equilibration) on the results with a minimum of experiments. The method was then validated for tactical intelligence purposes (batch comparison) via several studies: selection of solvents and mathematical comparison tool, reproducibility and "cutting" influence studies. The decision threshold to determine the similarity of two samples was set and false positives and negatives evaluated. Finally, application of the method to distinguish geographical origins is discussed.     

Rapid separation and characterization of cocaine and cocaine cutting agents by differential mobility spectrometry-mass spectrometry

Forensic drug laboratories are inundated with cases requiring time-consuming GC- or LC-based chromatographic separations of submitted samples. High-throughput analytical methods would be of great practical utility within forensic drug analysis. Recently developed ion-mobility-based separation methods combined with mass spectrometry can often be used without chromatography, suppress chemical interferents of similar mass, and operate in seconds. We have evaluated differential mobility spectrometry-mass spectrometry (DMS-MS) for performance on adulterated cocaine mixtures. The DMS interface is only a few centimeters in length, operates in seconds, and can be adapted to any MS system using atmospheric pressure ionization. Drug cutting agents, typical targets such as cocaine, and drug metabolites are rapidly separated by the DMS ion prefilter. Tests demonstrated characterization of complex mixtures, such as isolation of levamisole, an adulterant with alarming side effects, from a 13-component mixture. DMS-MS holds great potential for the analysis of drug samples submitted for forensic analysis.     

Levels of cocaine and its metabolites in washed hair of demonstrated cocaine users and workplace subjects

In a study of subjects in drug rehabilitation programs, cocaine and cocaine metabolite levels were determined in the hair of 75 subjects who had produced cocaine-positive urine results. The hair was analyzed after being washed with the 3.75 h wash procedure developed by this laboratory. In addition, results of testing 73 non-users are presented, as well as levels of cocaine, benzoylecgonine (BE), cocaethylene, and norcocaine from workplace population samples. The data support a recommendation of reporting as positive a sample with cocaine of 500 pg/mg hair and either a 5% ratio of benzoylecgonine (BE) to cocaine in samples, or the presence of cocaethylene at 50 pg/mg hair, or norcocaine at 50 pg/mg hair for samples < or =2000 pg cocaine/mg hair. For samples with cocaine present at >2000 pg/mg hair, the data indicate that a ratio of 5% BE may be an overly conservative approach. In appropriately washed hair samples, cocaine users can produce hair levels of <5% BE and thus a minimum BE cutoff in lieu of a ratio could be considered.