Direct analysis in real time mass spectrometry for analysis of sexual assault evidence
ABSTRACT Sexual assault crimes are vastly underreported and suffer from alarmingly low prosecution and conviction rates. The key scientific method to aid in prosecution of such cases is forensic DNA analysis, where biological evidence such as semen collected using a rape test kit is used to determine a suspect's DNA profile. However, the growing awareness by criminals of the importance of DNA in the prosecution of sexual assaults has resulted in increased condom use by assailants as a means to avoid leaving behind their DNA. Thus, other types of trace evidence are important to help corroborate victims' accounts, exonerate the innocent, link suspects to the crime, or confirm penetration.
Direct Analysis in Real Time Mass Spectrometry (DART-MS) was employed for the comprehensive characterization of non-DNA trace evidence associated with sexual assault. The ambient ionization method associated with DART-MS is extremely rapid and samples are processed instantaneously, without the need for extraction, sample preparation, or other means that might compromise forensic evidence for future analyses.
In a single assay, we demonstrated the ability to identify lubricant formulations associated with sexual assault, such as the spermicide nonoxynol-9, compounds used in condom manufacture, and numerous other trace components as probative evidence. In addition, the method can also serve to identify compounds within trace biological residues, such as fatty acids commonly identified in latent fingerprints.
Characterization of lubricant residues as probative evidence serves to establish a connection between the victim and the perpetrator, and the availability of these details may lead to higher rates of prosecution and conviction, as well as more severe penalties. The methodology described here opens the way for the adoption of a comprehensive, rapid, and sensitive analysis for use in crime labs, while providing knowledge that can inform and guide criminal justice policy and practice.
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ABSTRACT: The emergence of numerous cannabinoid designer drugs has been tied to large spikes in emergency room visits and overdoses. Identifying these substances is difficult for the following reasons: (1) the compounds are novel, closely structurally related, and do not usually test positive in drug screens; (2) novel analogs rapidly appear on the market; (3) no standard protocols exist for their identification; and (4) customized and extensive sample preparation/extraction and analysis procedures are required to demonstrate their presence. Direct analysis in real time mass spectrometry (DART-MS) employing collision-induced dissociation (CID) provided confirmatory structural information that was useful in characterizing the various cannabinoid analogs, including those contained in mixtures. CID analysis illustrated that, although closely related compounds fragment in a similar fashion, their structural differences still resulted in multiple diagnostic peaks that provided additional confidence towards structural identification. DART-MS spectra were acquired under CID conditions to rapidly differentiate among five synthetic cannabinoids contained within 'herbal' products purchased locally in New York State (USA). The spectra exhibited [M+H](+) ions and product ions unique to each cannabinoid that corresponded to major structural features. Five different cannabinoid analogs, alone and as mixtures of at least two cannabinoids, were identified in six herbal products and differentiated by their CID product ion patterns. Illicit synthetic cannabinoid products continue to be readily available despite national and international restrictions. These products contain a wide range of active components, and, in many cases, multiple active ingredients. DART-MS allows rapid analyses of these synthetic cannabinoids based on the exact masses of their [M+H](+) ions and product ion peaks generated using CID. Copyright © 2012 John Wiley & Sons, Ltd.Rapid Communications in Mass Spectrometry 10/2012; 26(19):2335-42. DOI:10.1002/rcm.6354 · 2.64 Impact Factor
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ABSTRACT: Normal phase chiral LC (NPLC) has been proved to be powerful and efficient for chiral separation. However, the combination of NPLC with ESI or atmospheric pressure chemical ionization MS is restricted by the poor ionization efficiency and thermal fragmentations of analytes to some extent. Direct analysis in real time MS (DART-MS) is an ambient ionization technique that shows high ionization efficiency of the analytes in the normal phase mobile phase. In this work, we coupled chiral NPLC to DART-MS for the chiral qualitative and quantitative analysis of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and jasmonic acid enantiomers. Satisfactory results for the enantiomers of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol operating in the positive mode were obtained in terms of linearity (2.5-250 μg/mL, R(2) , 0.999-1.000) and repeatability (25 μg/mL, RSDs, 4.7-5.6%). Moreover, chiral NPLC-DART-MS resulted in the simultaneous chiral separation and detection of jasmonic acid enantiomers, which are very difficult to be analyzed by NPLC-ESI-MS and NPLC-APCI-MS. Compared with the coupled techniques of NPLC-ESI-MS and NPLC-APCI-MS, NPLC-DART-MS showed advantages in increasing the ionization efficiency and reducing the in-source thermal fragmentation of analytes.Electrophoresis 11/2012; 33(22). DOI:10.1002/elps.201200122 · 3.16 Impact Factor
- Chemical Reviews 01/2013; 113(4). DOI:10.1021/cr300309q · 45.66 Impact Factor