From Extra Virgin Olive Oil to Refined Products: Intensity and Balance Shifts of the Volatile Compounds versus Odor

To explore relationships between the volatile organic compounds (VOCs) of different grades of olive oils (OOs) (extra virgin olive oil (EVOO), refined olive oil (ROO), and pomace olive oil (POO)) and odor quality, VOCs were measured in the headspace of the oils by proton transfer reaction quadrupole ion guide time-of-flight mass spectrometry. The concentrations of most VOCs differed significantly between the grades (EVOO > ROO > POO), whereas the abundance of m/z 47.012 (formic acid), m/z 49.016 (fragments), m/z 49.027 (fragments), and m/z 115.111 (heptanal/heptanone) increased in that order. Although the refined oils had considerably lower VOC abundance, the extent of the decline varied with the VOCs. This results in differences in VOCs proportions. The high VOC abundance in the EVOO headspace in comparison to ROO and POO results in a richer and more complex odor. The identified C5–C6 compounds are expected to contribute mainly to the green odor notes, while the identified C1–C4 and C7–C15 are mainly responsible for odor defects of OOs. Current results reveal that processing strongly affects both the quantitative and relative abundance of the VOCs and, therefore, the odor quality of the various grades of OOs.

Characterization of an improved PTR3 mass spectrometer for the detection of highly oxidized aerosol precursors

<p>The recently introduced PTR3-TOF mass spectrometer (Proton Transfer Reaction Time-Of-Flight) allows for a direct and quantitative detection of volatile organic compounds (VOC) and their oxidation products. With a design of the inlet system and the ionization chamber that allows analyte transfer with virtually no wall interactions, organics ranging from volatile to extremely low volatility (ELVOC) can be measured, even at ambient temperature. In addition, PTR3 has recently shown to detect and quantify RO<sub>2 </sub>radicals. Unlike the traditional PTR-MS ionization technique, the PTR3 is operated at an elevated reaction pressure of 50 to 80 mbar while reaction kinetics are precisely defined via radial electric fields emitted from a tripole ion guide. With this setup, outstanding sensitivities of more than 30,000 cps/ppbV are achieved.</p><p>Herein, we present an improved version of a PTR3-TOF instrument. The inlet comprises three cylindrically arranged ion sources allowing for fast electrical switching between a set of reagent ions including H<sub>3</sub>O<sup>+</sup>, NO<sup>+</sup>, O<sub>2</sub><sup>+</sup> and NH<sub>4</sub><sup>+</sup>. The tripole geometry is aerodynamically improved to further reduce surface interactions. Extraction of analyte ions from the PTR3 ionization chamber and subsequent transfer to the TOF mass analyzer is now enhanced by an ion booster in series to a hexapole ion guide. This setup enables a precise control of extraction energies to reduce unwanted collision induced fragmentation and at the same time efficiently transmits ions of a broad m/z range. Analyte ions are analyzed with a high-resolution Time-Of-Flight mass spectrometer achieving mass resolving powers of typically 13,000 to 15,000.</p><p>We have characterized the performance of this optimized PTR3-TOF instrument using pure chemical compounds of intermediate to low volatility, including carboxylic acids and peroxides. Hereby, the effects of PTR3 reaction conditions and ion extraction settings are studied. Monoterpene ozonolysis experiments demonstrate the performance in detecting aerosol precursors from intermediate to extremely low volatility. These new insights in gas phase chemistry are further combined with particle phase measurements conducted with a CHARON PTR-MS to emphasize the analytical capabilities of the PTR3.</p>

Fission studies at IGISOL/JYFLTRAP: Simulations of the ion guide for neutron-induced fission and comparison with experimental data

For the production of exotic nuclei at the IGISOL facility, an ion guide for neutron-induced fission has been developed and tested in experiments. Fission fragments are produced inside the ion guide and collected using a helium buffer gas. Meanwhile, a GEANT4 model has been developed to simulate the transportation and stopping of the charged fission products. In a recent measurement of neutron-induced fission yields, implantation foils were located at different positions in the ion guide. The gamma spectra from these foils and the fission targets are compared to the results from the GEANT4 simulation. In order to allow fission yield measurements in the low yield regions, towards the tails and in the symmetric part of the mass distribution, the stopping and extraction efficiency of the ion guide has to be significantly improved. This objective can be achieved by increasing the size while introducing electric field guidance using a combination of static electrodes and an RF-carpet. To this end, the GEANT4 model is used to optimise the design of such an ion guide.

Исследование состава остаточного газа в вакуумной системе циклотрона ФТИ им. А.Ф. Иоффе

4. Using the FT-200 compact-size time-of-flight mass spectrometer developed at the Ioffe Institute, the mass spectra of the residual gas molecules in the vacuum system of the Ioffe Institute cyclotron have been obtained under various experimental conditions. The measurements were carried out in the cyclotron vacuum chamber and the end part of the ion guide near the sample irradiation chamber. It was found that the main contribution to the residual gas composition in the cyclotron chamber is made by the molecules of pump oil used (up to 82%) and water molecules (up to 15-17%), and in the ion guide near the irradiation chamber with a polymer film - water molecules (up to 63%). The data obtained are the basis for the modernization of the Ioffe cyclotron complex.