Small- and large-sized iron(II, III) oxide nanoparticles for surface-assisted laser desorption/ionization mass spectrometry of small biomolecules.

Rationale: Common surface-assisted laser desorption/ionization (SALDI) surfaces are functionalized to improve mass spectrometric detection. Such surfaces are selective to certain group(s) of compounds. The application of universal and sensitive SALDI surfaces with appropriate size/surface area is paramount.

The reaction between GSNO and HS: On the generation of NO, HNO and NO.

Several recent reports suggest that HNO may be produced endogenously by reaction of HS and S-nitrosoglutathione (GSNO). This hypothesis was tested using deoxymyoglobin (MbFe) to trap the expected HNO released from the target reaction, which should generate the stable HNO adduct, HNO-Mb, under anaerobic conditions. Under numerous experimental conditions, the sole globin product was NO-Mb, as characterized by absorbance, EPR, and NMR spectroscopies.

Green Synthesis of Halogenated Thiophenes, Selenophenes and Benzo[]selenophenes Using Sodium Halides as a Source of Electrophilic Halogens.

Herein, we report the first synthesis of chlorinated benzo[]selenophenes via environmentally friendly electrophilic chlorocyclization reaction using "table salt" as a source of "electrophilic chlorine" and ethanol as a solvent. In addition, the synthesis of diverse halogenated heterocycles, including 3-chloro, 3-bromo and 3-iodo thiophenes, selenophenes, and benzo[]selenophenes was successfully accomplished under the same environmentally benign reaction conditions. This methodology has several advantages over other previously reported reactions as it employs simple starting compounds, an environmentally friendly solvent, ethanol, and non-toxic inorganic reagents under mild reaction conditions, resulting in the high product yields.

Transition metal oxide nanoparticles as surfaces for surface-assisted laser desorption/ionization mass spectrometry of asphaltenes.

We report the first use of NiO, FeO, TiO, and CoO nanoparticles as surfaces for surface-assisted laser desorption/ionization (SALDI) mass spectrometry of asphaltenes. Higher ratios (S/Ns) for asphaltene species were observed using NiO and FeO nanoparticles for SALDI as compared to LDI, where both surfaces consistently provided 2- to 3-fold improved S/Ns. The new SALDI detection method showed reliable adsorption data measuring supernatant solutions after 24 hour asphaltene adsorption on NiO, FeO, and CoO.

Evidence for electron-based ion generation in radio-frequency ionization.

Radio-frequency ionization (RFI) is a novel ionization method coupled to mass spectrometry (MS) for analysis of semi-volatile and volatile organic compounds (VOCs). Despite the demonstrated capabilities of RFI MS for VOC analysis in both positive- and negative-ion modes, mechanism of RFI is not completely understood. Improved understanding of the ion generation process in RFI should expand its utility in MS.

Competing noncovalent host-guest interactions and H/D exchange: reactions of benzyloxycarbonyl-proline glycine dipeptide variants with ND3.

A combination of density functional theory calculations, hydrogen/deuterium exchange (HDX) reactions, ion mobility-mass spectrometry, and isotope labeling tandem mass spectrometry was used to study gas-phase "host-guest" type interactions of a benzyloxycarbonyl (Z)-capped proline (P) glycine (G) model dipeptide (i.e., Z-PG) and its various structural analogues with ND3.

Efficient injection of low-mass ions into high magnetic field Fourier transform ion cyclotron resonance mass spectrometers.

Rationale: Low-mass cut-off restrictions for injecting ions from external ion sources into high magnetic fields impose limitations for wide mass range analyses with Fourier transform ion cyclotron resonance (FTICR) instruments. Radio-frequency (RF)-only quadrupole ion guides (QIGs) with higher frequencies can be used to overcome low-mass cut-off in FTICR instruments.

Methods: RF signals (1.