(Un)targeted Scanning of Locks of Hair for Drugs of Abuse by Direct Analysis in Real Time-High-Resolution Mass Spectrometry
Anal. Chem., January 27, 2016 (Web): - DOI: 10.1021/acs.analchem.5b04759
Forensic hair evidence can be used to obtain retrospective timelines of drug use by analysis of hair segments. However, this is a laborious and time-consuming process, and mass spectrometric (MS) imaging techniques, which show great potential for single-hair targeted analysis, are less useful due to differences in hair growth rate between individual hairs. As an alternative, a fast untargeted analysis method was developed that uses direct analysis in real time-high-resolution mass spectrometry (DART-HRMS) to longitudinally scan intact locks of hair without extensive sample preparation or segmentation. The hair scan method was validated for cocaine against an accredited liquid chromatography/tandem mass spectrometry (LC/MS/MS) method. The detection limit for cocaine in hair was found to comply with the cutoff value of 0.5 ng/mg recommended by the Society of Hair Testing; that is, the DART hair scan method is amenable to forensic cases. Under DART conditions, no significant thermal degradation of cocaine occurred. The standard DART spot size of 5.1 ± 1.1 mm could be improved to 3.3 ± 1.0 mm, corresponding to approximately 10 days of hair growth, by using a high spatial resolution exit cone. By use of data-dependent product ion scans, multiple drugs of abuse could be detected in a single drug user hair scan with confirmation of identity by both exact mass and MS/HRMS fragmentation patterns. Furthermore, full-scan high-resolution data were retrospectively interrogated versus a list of more than 100 compounds and revealed additional hits and temporal profiles in good correlation with reported drug use
Analysis of carbohydrates in Fusarium verticillioides using size-exclusion
HPLC-DRI and DART-TOF-MS
Mund-Lagowski Department of Chemistry and Biochemistry, Bradley University, Peoria, USA
Bacterial Foodborne Pathogens and Mycology Research, USDA-ARS-NCAUR, Peoria, USA
Anal. Methods, 2016, 8, 673-681
Direct analysis in real time ionization - time-of-flight - mass spectrometry (DART-MS) and size-exclusion HPLC - DRI are used, respectively, to qualitatively and quantitatively determine the carbohydrates extracted from the corn rot fungus Fusarium verticillioides. In situ permethylation in the DART beam forms tri-methylammonium adducts of the carbohydrates, which enables positive ion MS detection and analysis of these compounds in either whole fungal extracts or size-exclusion separated HPLC fractions of the extracts. This method detects the disaccharide trehalose at concentrations greater than 3.0 ppm. Additionally, this procedure allows for analysis of glucose as well as the sugar alcohols mannitol, arabitol, and glycerol. The reliability of the DART-MS method is confirmed by the absence of trehalose in a mutant strain of F. verticillioides lacking the gene for trehalose-6-phosphate synthase. The capabilities demonstrated here suggest that the DART-MS method, in conjunction with size-exclusion HPLC, is an effective approach for the analysis of saccharide biomarkers in fungi.
Petroleomics by Direct Analysis in Real Time-Mass Spectrometry
Romão, Tose, Vaz, Sama, Lobinski, Giusti, Carrier and Bouyssiere
Lab de Petroleômica e Forense, Departamento de Química, Univ Federal do Espírito Santo, Vitória, ES, Brazil LCABIEIPREM, Université de Pau et des Pays de l'Adour
The analysis of crude oil and its fractions by applying ambient ionization techniques remains underexplored in mass spectrometry (MS). Direct analysis in real time (DART) in the positive-ion mode was coupled to a linear quadrupole ion trap Orbitrap mass spectrometer (LTQ Orbitrap) to analyze crude oil, paraffin samples, and porphyrin standard compounds. The ionization parameters of DART-MS were optimized for crude oil analysis. DART-MS rendered the optimum conditions of the operation using paper as the substrate, T = 400°C, helium as the carrier gas, and a sample concentration ≥6 mg mL-1. In the crude oils analysis, the DART(+)-Orbitrap mass spectra detected the typical N, NO, and O-containing compounds. In the paraffin samples, oxidized hydrocarbon species (Ox classes, where x = 1-4) with double-bond equivalent of 1-4 were detected, and their structures and connectivity were confirmed by collision-induced dissociation (CID) experiments. DART(+)-MS has identified the porphyrin standard compounds as [M + H]+ ions of m/z 615.2502 and 680.1763, where M = C44H30N4 and C44H28N4OV, respectively, based on the formula assignment and by phenyl losses observed on CID experiments
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