9 research outputs found
Molecular Characterization of the Thermal Degradation of Per- and Polyfluoroalkyl Substances in Aqueous Film-Forming Foams via Temperature-Programmed Thermal Desorption–Pyrolysis–Direct Analysis in Real Time–Mass Spectrometry
The release of aqueous film-forming foam (AFFF), containing
per-
and polyfluoroalkyl substances (PFAS), from Department of Defense
activities has received attention over the years due to the environmental
persistence and bioaccumulation of PFAS. As a result, the National
Defense Act established that the removal of PFAS-containing waste
is critical. Thermal destruction methods are commonly used techniques,
yet the fate of degraded PFAS remains poorly understood. In this study,
we employ thermal desorption–pyrolysis–direct analysis
in real time–mass spectrometry (TD-pyro-DART-MS) to characterize
products of pyrolysis and determine the extent of degradation from
25 to 600 °C. PFAS ranging from 4–14 carbon atoms were
monitored in situ, followed by legacy AFFF. Headgroup
scission was observed, followed by carbon–carbon bond cleavages
in the structures resulting in [CxFy]− fragments differing
by -CF2 (50 Da) and -C2F4 (100 Da).
High-molecular weight PFAS resulted in more detectable pyrolytic fragments
than low-molecular weight counterparts. AFFF concentrate thermal degradation
analysis was more complex and was determined to require higher-resolution
mass spectrometers for molecular assignment. This study demonstrates
the development of a robust analytical methodology for in
situ characterization of the products of thermal degradation
of PFAS related to thermal remediation or when PFAS are used to extinguish
fuel fires
Novel selectivity-based forensic toxicological validation of a paper spray mass spectrometry method for the quantitative determination of eight amphetamines in whole blood
FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOPaper spray tandem mass spectrometry is used to identify and quantify eight individual amphetamines in whole blood in 1.3 min. The method has been optimized and fully validated according to forensic toxicology guidelines, for the quantification of ampheta281226652676FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO2016/01683-
Novel Selectivity-Based Forensic Toxicological Validation of a Paper Spray Mass Spectrometry Method for the Quantitative Determination of Eight Amphetamines in Whole Blood
Paper spray tandem mass spectrometry is used to identify and quantify eight individual amphetamines in whole blood in 1.3 min. The method has been optimized and fully validated according to forensic toxicology guidelines, for the quantification of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-methylamphetamine (MDMA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), para-methoxyamphetamine (PMA), para-methoxymethamphetamine (PMMA), and 4-fluoroamphetamine (4-FA). Additionally, a new concept of intrinsic and application-based selectivity is discussed, featuring increased confidence in the power to discriminate the amphetamines from other chemically similar compounds when applying an ambient mass spectrometric method without chromatographic separation. Accuracy was within ±15% and average precision was better than 15%, and better than 20% at the LLOQ. Detection limits between 15 and 50 ng/mL were obtained using only 12 μL of whole blood. [Figure not available: see fulltext.]
A Low-Cost, Simplified Platform of Interchangeable, Ambient Ionization Sources for Rapid, Forensic Evidence Screening on Portable Mass Spectrometric Instrumentation
Portable mass spectrometers (MS) are becoming more prevalent due to improved instrumentation, commercialization, and the robustness of new ionization methodologies. To increase utility towards diverse field-based applications, there is an inherent need for rugged ionization source platforms that are simple, yet robust towards analytical scenarios that may arise. Ambient ionization methodologies have evolved to target specific real-world problems and fulfill requirements of the analysis at hand. Ambient ionization techniques continue to advance towards higher performance, with specific sources showing variable proficiency depending on application area. To realize the full potential and applicability of ambient ionization methods, a selection of sources may be more prudent, showing a need for a low-cost, flexible ionization source platform. This manuscript describes a centralized system that was developed for portable MS systems that incorporates modular, rapidly-interchangeable ionization sources comprised of low-cost, commercially-available parts. Herein, design considerations are reported for a suite of ambient ionization sources that can be crafted with minimal machining or customization. Representative spectral data is included to demonstrate applicability towards field processing of forensic evidence. While this platform is demonstrated on portable instrumentation, retrofitting to lab-scale MS systems is anticipated
Simultaneous Online Monitoring of Multiple Reactions Using a Miniature Mass Spectrometer
Advances in chemical
sampling using miniature mass spectrometer
technology are used to monitor slow reactions at a frequency of ca.
180 h<sup>–1</sup> (on the Mini 12) with no sample carryover
and with inline derivatization in the case of poorly ionizing compounds.
Moreover, we demonstrate high reproducibility with a relative error
of less than 10% for major components. Monitoring is enabled using
a continuous-flow nanoelectrospray (CF-nESI) probe contained in a
custom-built 3D-printed rotary holder. The holder position is automatically
set using a stepper motor controlled by a microcontroller. Reaction
progress of up to six reactions, including hydrazone formation and
Katritzky transamination, can be monitored simultaneously without
carryover for several hours