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Analytical and Bioanalytical Chemistry (v.376, #8)
Forensic analysis
by Susan Ballou; John Goodpaster; William MacCrehan; Dennis Reeder (pp. 1149-1150).
How do I become a forensic scientist? Educational pathways to forensic science careers
by R. E. Gaensslen (pp. 1151-1155).
Trends in forensic science education: expansion and increased accountability
by Jose R. Almirall; Kenneth G. Furton (pp. 1156-1159).
Quantification of DNA in forensic samples by Janice A. Nicklas; Eric Buel (pp. 1160-1167).
Quantification of DNA in a forensic sample is of major importance for proper DNA amplification and STR profiling. Several methods have been developed to quantify DNA, from basic UV spectrometry, through gel-based techniques, to dye staining, blotting techniques, and, very recently, DNA amplification methods (polymerase chain reaction, PCR). Early techniques simply measured total DNA, but newer techniques can specifically measure human DNA while excluding non-human DNA (foodstuff, animal, or bacterial contamination). These newer assays can be faster and less expensive than traditional methods, making them ideal for the busy forensic laboratory. This paper reviews classic and newer quantification techniques and presents methods recently developed by the authors on the basis of PCR of Alu sequences.
Keywords: Forensic science; DNA quantification; Alu sequences; Polymerase chain reaction; Real-time; Human
Recent advances in the applications of forensic science to fire debris analysis by J. Dolan (pp. 1168-1171).
The forensic discipline of ignitable liquid and fire debris analysis is rapidly changing. Refinements in existing methods as well as development of new techniques are changing the routine methods of analysis. Optimization of existing extraction techniques and research into novel methods of extracting debris have improved the recovery of ignitable liquids from debris samples. The application of highly specialized instrumentation to problems of sensitivity and matrix interference has resulted in new ways of performing chemical analyses, allowing for improved limits of detection. Preliminary research in novel approaches to ignitable liquid comparisons is being evaluated, with the hopes of providing more detailed information to the field investigators. Research into a variety of areas related to fire debris analysis is ongoing, and will continue to improve the quality of ignitable liquid residue analysis.
Keywords: Fire debris; Ignitable liquid analysis; Arson; Gas chromatography-mass spectrometry
The European Fibres Group (EFG) 1993–2002: "Understanding and improving the evidential value of fibres" by K. G. Wiggins (pp. 1172-1177).
The paper outlines the history of the European Fibres Group (EFG) and includes its aims and achievements from the time of its formation in 1993 to the present day. The main emphasis is on the subject of "the evidential value of fibres", how the EFG have provided the data and where to locate it. Additionally the paper provides a look into what the group has accomplished in the recognition of the "lack of data" and the research being conducted to correct this problem. Finally it outlines other projects that are underway to improve its members' knowledge.
Keywords: European Fibres Group; Evidential value; Fibre; Interpretation; Colour; Research and development
Recent developments in methods of chemical analysis in investigations of firearm-related events by Arie Zeichner (pp. 1178-1191).
examination of gunshot (primer) residues (GSR) and gunpowder (propellant) residues on suspects and their clothing;detection of firearm imprints on the hands of suspects;identification of the bullet entry holes and estimation of shooting distance;linking weapons and/or fired ammunition to the gunshot entries, andestimation of the time since discharge.
Keywords: Forensic science; Gunshot residue; GSR; Gunpowder residue; Shooting distance; Firearms; Time since discharge
Analytical developments in toxicological investigation of drug-facilitated sexual assault by Adam Negrusz; R. E. Gaensslen (pp. 1192-1197).
This paper gives a general overview of the drug-facilitated sexual assault phenomenon. Sexual assault perpetrated on both women and men, while incapacitated by so-called date-rape drugs, recently became the focus of many investigations conducted by law enforcement agencies in the US throughout the 1990s; an alarming increase in reports of this crime as well as in the number of scientific publications on drug-facilitated sexual assault has been observed. The list of drugs reportedly associated with sexual assault is long and among others includes flunitrazepam with other benzodiazepines such as diazepam, temazepam, clonazepam, oxazepam, as well as γ-hydroxybutyrate (GHB), ketamine, and scopolamine. We discuss the most recent analytical developments in the toxicological investigation of drug-facilitated rape designed to reveal drug presence and that may help successfully prosecute perpetrators.
Keywords: Drug-facilitated sexual assault; "Date-rape" drugs; Forensic toxicology; NCI–gas chromatography–mass spectrometry
Elimination of 7-aminoclonazepam in urine after a single dose of clonazepam by Adam Negrusz; Andrew M. Bowen; Christine M. Moore; Sheila M. Dowd; Mary Jane Strong; Philip G. Janicak (pp. 1198-1204).
The objective of this paper was to determine how long after administration of benzodiazepine clonazepam (CLO), its major metabolite 7-aminoclonazepam (7-ACLO) could be detected in urine collected from 10 healthy volunteers who received a single 3-mg dose of Klonopin (clonazepam). Such data would be of great importance to law enforcement agencies trying to determine the best time interval for urine collection from a victim of drug-facilitated sexual assault in order to reveal drug use. A highly sensitive NCI–GC–MS method for the simultaneous quantitation of CLO and its major metabolite 7-ACLO in urine was developed and validated. The following urine samples were collected from each volunteer: one before CLO administration, and 6 h, and 1, 3, 5, 8, 10, 14, 21 and 28 days after. All urine samples (1 mL) were extracted following addition of the internal standard (D5-diazepam) and enzymatic hydrolysis (β-glucuronidase) using solid-phase extraction columns. Standard curves for CLO (500–4000 pg mL−1) and 7-ACLO (50–2000 pg mL−1) were prepared by spiking aliquots of negative urine. The urine from every subject was still positive for 7-ACLO 14 days after administration of the drug. Eight of the ten volunteers had measurable amounts of the metabolite 21 days after administration. One volunteer was still positive 28 days after administration. Six of the volunteers had urine concentrations of 7-ACLO that peaked at 1 day after administration. One volunteer had the highest concentration of 7-ACLO at 3 days, two volunteers at 5 days, and one at 8 days. The range of concentrations detected was from 73.0 pg mL−1 to 183.2 ng mL−1. CLO was not detected in any of the samples.
Keywords: Drug-facilitated sexual assault; Date-rape drugs; Clonazepam; Solid-phase extraction; NCI–GC–MS
Two new standard reference materials for the determination of drugs of abuse in human hair by Michael J. Welch; Lorna T. Sniegoski; Susan Tai (pp. 1205-1211).
Two new standard reference materials (SRM) for drugs of abuse in human hair have been developed. SRM 2379 consists of hair spiked with cocaine, benzoylecgonine, cocaethylene, phencyclidine, amphetamine, and methamphetamine. SRM 2380 consists of hair spiked with codeine, morphine, monoacetylmorphine, and tetrahydrocannabinol (THC). The SRMs were prepared by soaking the hair in a solution of the target analytes in water-dimethylsulfoxide. The concentration of each analyte was determined using two methods, one based upon gas chromatography/mass spectrometry (GC/MS) and one based upon liquid chromatography/mass spectrometry (LC/MS). Both methods used 0.1 M HCl for extraction of all the analytes from the hair, except for THC, which was extracted with 1 M NaOH. For isolation of the analytes from the extracts, the GC/MS-based methods used different clean-up procedures from those used for the LC/MS-based methods. The results from the two methods were in good agreement with mean differences for the analytes ranging from 4% to 16%. These materials will enable laboratories performing analyses of hair for drugs of abuse to test the accuracy of their methods.
Keywords: Drugs of abuse; Hair analysis; GC/MS; LC/MS; Standard reference material
Laboratory and field experiments used to identify Canis lupus var. familiaris active odor signature chemicals from drugs, explosives, and humans by Norma Lorenzo; TianLang Wan; Ross J. Harper; Ya-Li Hsu; Michael Chow; Stefan Rose; Kenneth G. Furton (pp. 1212-1224).
This paper describes the use of headspace solid-phase microextraction (SPME) combined with gas chromatography to identify the signature odors that law enforcement-certified detector dogs alert to when searching for drugs, explosives, and humans. Background information is provided on the many types of detector dog available and specific samples highlighted in this paper are the drugs cocaine and 3,4-methylenedioxy-N-methylamphetamine (MDMA or Ecstasy), the explosives TNT and C4, and human remains. Studies include the analysis and identification of the headspace "fingerprint" of a variety of samples, followed by completion of double-blind dog trials of the individual components in an attempt to isolate and understand the target compounds that dogs alert to. SPME–GC/MS has been demonstrated to have a unique capability for the extraction of volatiles from the headspace of forensic specimens including drugs and explosives and shows great potential to aid in the investigation and understanding of the complicated process of canine odor detection. Major variables evaluated for the headspace SPME included fiber chemistry and a variety of sampling times ranging from several hours to several seconds and the resultant effect on ratios of isolated volatile components. For the drug odor studies, the CW/DVB and PDMS SPME fibers proved to be the optimal fiber types. For explosives, the results demonstrated that the best fibers in field and laboratory applications were PDMS and CW/DVB, respectively. Gas chromatography with electron capture detector (GC/ECD) and mass spectrometry (GC/MS) was better for analysis of nitromethane and TNT odors, and C-4 odors, respectively. Field studies with detector dogs have demonstrated possible candidates for new pseudo scents as well as the potential use of controlled permeation devices as non-hazardous training aids providing consistent permeation of target odors.
Keywords: Explosives; Drugs; Human remains; Canine detection; SPME
Development of microsatellite markers in Cannabis sativa for DNA typing and genetic relatedness analyses by H. J. Alghanim; J. R. Almirall (pp. 1225-1233).
Microsatellite markers were developed for Cannabis sativa L. (marijuana) to be used for DNA typing (genotype identification) and to measure the genetic relationships between the different plants. Twelve different oligonucleotide probes were used to screen an enriched microsatellite library of Cannabis sativa in which 49% of the clones contained microsatellite sequences. Characterization of microsatellite loci in Cannabis revealed that GA/CT was the most abundant class of the isolated microsatellites representing 50% overall followed by GTT/CAA, AAG/TTC, and GAT/CTA representing 16%, 15%, and 10%, respectively. Eleven polymorphic STR markers were developed, three derived from dinucleotide motifs and eight from trinucleotide motifs. A total of 52 alleles were detected averaging 4.7 alleles/locus. The expected heterozygosity of the eleven loci ranged between 0.368 and 0.710 and the common probability of identical genotypes was 1.8×10−7. The loci identified 27 unique profiles of the 41 Cannabis samples. The 11 microsatellite markers developed in this study were found to be useful for DNA typing and for assessing genetic relatedness in Cannabis.
Keywords: Cannabis sativa ; Marijuana; Microsatellite; Short tandem repeat (STR); DNA fingerprinting; DNA typing; Genetic relatedness
The development of an 18-locus Y-STR system for forensic casework by Ashley Hall; Jack Ballantyne (pp. 1234-1246).
The aim of the present work was to improve the discriminatory potential, and hence the probative value, of Y-STR-based testing by extending the set of Y chromosome STR loci available for forensic casework. In accordance with the requirements of a Y chromosome multiplex analytical system developed specifically for forensic casework use, we have sought to maximize the number of loci able to be co-amplified, ensure appropriate assay sensitivity (1–2 ng of input genomic DNA), balance inter-locus signals and minimize confounding female DNA artifacts. Two Y chromosome STR systems, multiplex I (MPI) and multiplex II (MPII), have been developed which permit the robust co-amplification of 18 Y-STRs. The loci include DYS19, DYS385(a) and (b), DYS388, DYS389I and II, DYS390, DYS391, DYS392, DYS393, DYS425, DYS434, DYS437, DYS438, DYS439, Y-GATA-C4, Y-GATA-A7.1 (DYS460) and Y-GATA-H4. The two multiplex systems are robust over a wide range of primer, magnesium, and DNA polymerase concentrations and perform well under a variety of cycling conditions. Complete male haplotypes can be obtained with as little as 100–250 pg of template DNA. Although a limited number of female DNA artifacts are observed in mixed stains in which the male DNA comprises 1/100 of the total, the male profile is easily discernible. Slightly modified versions of MPI and MPII demonstrate a significant reduction in female artifacts. Thus, it may not be necessary to employ a differential extraction strategy to obtain a male haplotype (or haplotypes in the case of multiple male donors) in cases of sexual assault. The potential utility of MPI and MPII for forensic casework is exemplified by their ability to dissect out the male haplotype in post-coital vaginal swabs and to determine the number of male donors in mixed semen stains.This study has emphasized the need for novel Y-STR multiplexes developed for forensic use to undergo a series of validation exercises that go beyond simply optimizing the PCR reaction conditions. Specifically, stringent performance checks on their efficacy need to be carried out using casework-type specimens in order to determine potential confounding effects from female DNA.
Keywords: Y chromosome markers; Post-coital vaginal swabs; Multiplex Y-STR analysis
Precision studies using the ABI Prism 3100 Genetic Analyzer for forensic DNA analysis by Joanne B. Sgueglia; Stephana Geiger; Jeffrey Davis (pp. 1247-1254).
Precision studies using the ABI Prism 3100 Genetic Analyzer have been conducted by performing multiple runs of the AmpFℓSTR Identifiler allelic ladder, 9947A kit positive control DNA and the 250-base-pair fragment from the internal size standard (GeneScan LIZ-500). Intra-run and inter-run precision data demonstrates the sizing reproducibility of the 3100 instrument for forensic applications. This precision data is utilized to assist in making allele assignments for outlier and variant alleles (i.e., 'off-ladder' alleles). It also provides a means of addressing systematic variations due to temperature fluctuations, polymer (POP-4) or capillary effects, and associated troubleshooting efforts.
Keywords: DNA; STR; Capillary electrophoresis; Precision
Analysis and comparison of glass fragments by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and ICP-MS by Tatiana Trejos; Shirly Montero; José R. Almirall (pp. 1255-1264).
The discrimination potential of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) is compared with previously reported solution ICP-MS methods using external calibration (EC) with internal standardization and a newly reported solution isotope dilution (ID) method for the analysis of two different glass populations. A total of 91 different glass samples were used for the comparison study; refractive index and elemental composition were measured by the techniques mentioned above. One set consisted of 45 headlamps taken from a variety of automobiles that represents a range of 20 years of manufacturing dates. A second set consisted of 46 automotive glasses (side windows, rear windows, and windshields) representing casework glass from different vehicle manufacturers over several years. The element menu for the LA-ICP-MS and EC-ICP-MS methods include Mg, Al, Ca, Mn, Ce, Ti, Zr, Sb, Ga, Ba, Rb, Sm, Sr, Hf, La, and Pb. The ID method was limited to the analysis of two isotopes each of Mg, Sr, Zr, Sb, Ba, Sm, Hf, and Pb. Laser ablation analyses were performed with a Q switched Nd:YAG, 266 nm, 6 mJ output energy laser. The laser was used in depth profile mode while sampling using a 50 μm spot size for 50 sec at 10 Hz (500 shots). The typical bias for the analysis of NIST 612 by LA-ICP-MS was less than 5% in all cases and typically better than 5% for most isotopes. The precision for the vast majority of the element menu was determined generally less than 10% for all the methods when NIST 612 was measured (40 μg g-1). Method detection limits (MDL) for the EC and LA-ICP-MS methods were similar and generally reported as less than 1 μg g-1 for the analysis of NIST 612. While the solution sample introduction methods using EC and ID presented excellent sensitivity and precision, these methods have the disadvantages of destroying the sample, and also involve complex sample preparation. The laser ablation method was simpler, faster, and produced comparable discrimination to the EC-ICP-MS and ID-ICP-MS. LA-ICP-MS can offer an excellent alternative to solution analysis of glass in forensic casework samples.
Keywords: Glass; Laser ablation; ICP-MS; Elemental analysis; Trace evidence; Forensic science
Trace elemental analysis of automotive paints by laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) by Andria L. Hobbs; José R. Almirall (pp. 1265-1271).
Paints and coatings are frequently encountered as types of materials that are submitted to forensic science laboratories as a result of trace evidence transfers. The aim of this study was to develop a method to complement the commonly used techniques in a forensic laboratory in order to better characterize these samples for forensic purposes. A laser ablation method has been used to simultaneously sample several layers directly prior to introduction into an inductively coupled plasma–mass spectrometer for the detection and quantification of the trace metals present in the layer(s). Time-resolved analysis plots displaying the elemental response and quantification of selected metals are compared to associate/discriminate paint samples. Matrix-matched standards were successfully incorporated into the analysis scheme for quantification of lead in the solid paint samples. Preparation of new matrix-matched standards for quantification of additional elements developed for this study are also presented. A sample set of eighteen (18) survey automotive paint samples have been analyzed with the developed method in order to determine the utility of LA–ICP–MS for trace element analysis of paints.
Keywords: Forensic science; Trace evidence; Automotive paint; Elemental analysis; Laser ablation–inductively coupled plasma–mass spectrometry
Forensic discrimination of photocopy and printer toners I. The development of an infrared spectral library by Rena A. Merrill; Edward G. Bartick; J. Hollis Taylor III (pp. 1272-1278).
Microscopical reflection-absorption by infrared spectroscopy (R-A IR) was shown as a viable technique for analyzing the polymer resins contained in dry, black photocopy and printer toners. The sampling technique involves a heat transfer of the toner from a document to the reflective surface of aluminum foil followed by analysis by R-A IR. The technique is simple, fast, and readily available to most forensic laboratories. A searchable spectral library was created that contains 807 toner samples analyzed by R-A IR. Ninety-eight groups were established based on spectral characteristics, and a flowchart was developed to assist with group assignments. A blind study was conducted to compare twenty photocopied documents each paired to a test document to determine if the pair could have been produced from the same copier. The analyst obtained 100% correct results in this study. Tests on thirty samples with the spectral library produced 90% first hits for the correct group. The three remaining samples were correctly determined by visual comparison of spectra for the top three hits. An actual case study was conducted where the investigation was narrowed from 400 possible machines to eight based on a comparative study of the photocopy toners.
Keywords: Questioned documents; Photocopy toner; Infrared microscopical analysis; Reflection-absorption infrared spectroscopy; Spectral library
Forensic discrimination of photocopy and printer toners II. Discriminant analysis applied to infrared reflection-absorption spectroscopy by William J. Egan; Stephen L. Morgan; Edward G. Bartick; Rena A. Merrill; Hollis J. Taylor III (pp. 1279-1285).
Copy toner samples were analyzed using reflection-absorption infrared microscopy (R-A IR). The grouping of copy toners into distinguishable classes achieved by visual comparison and computer-assisted spectral matching was compared to that achieved by multivariate discriminant analysis. For a data set containing spectra of 430 copy toners, 90% (388/430) of the spectra were initially correctly grouped into the classifications previously established by spectral matching. Three groups of samples that did not classify well contained too few samples to allow reliable classification. Samples from two other pairs of groups were similar and often misclassified. Closer examination of spectra from these groups revealed discriminating features that could be used in separate discriminant analyses to improve classification. For one pair of groups, the classification accuracy improved to 91% (81/89) and 97% (28/29), for the two groups, respectively. The other pair of groups were completely distinguishable from one another. With these additional tests, multivariate discriminant analysis correctly classified 96% of the 430 R-A IR toner spectra into the toner groups found previously by spectral matching.
Keywords: Pattern recognition; Discriminant analysis; Questioned documents; Photocopy toner; Reflection-absorption infrared spectroscopy; Spectral library
Forensic discrimination of photocopy and printer toners. III. Multivariate statistics applied to scanning electron microscopy and pyrolysis gas chromatography/mass spectrometry by William J. Egan; Randolph C. Galipo; Brian K. Kochanowski; Stephen L. Morgan; Edward G. Bartick; Mark L. Miller; Dennis C. Ward; Robert F. Mothershead II (pp. 1286-1297).
Copy toner samples were analyzed using scanning electron microscopy with X-ray dispersive analysis (SEM–EDX) and pyrolysis gas chromatography/mass spectrometry (Py–GC/MS). Principal component and cluster analysis of SEM data for 166 copy toner samples established 13 statistically different subgroups, with the presence or absence of a ferrite base being a major division. When toners were compared for which both SEM and reflection–absorption infrared spectral data were available, 41% of the samples could be assigned to specific manufacturers. Py–GC/MS on poly(styrene:acrylate)-based toners produced eight peaks relevant to toner differentiation. One third of the toners clustered in a small group that contained five statistically different subgroups. Of the 57 toners for which both Py–GC/MS and SEM data were available, 31 could be differentiated using the combined analytical results. The synergy of the complementary information provided by Py–GC/MS and SEM narrows matching possibilities for forensic investigations involving copied or laser printed documents.
Keywords: Principal component analysis; Cluster analysis; Questioned documents; Copy toner; Scanning electron microscopy; Pyrolysis gas chromatography/mass spectrometry; Infrared microspectroscopy.