30 research outputs found
Determination of aliphatic acids in natural waters using distillation and solid-phase extraction
A procedure is developed and conditions are optimized for the pretreatment of natural water using distillation with no prefiltration of acidified water in combination with preconcentration by solid-phase extraction (SPE) on a Strata-X polymeric adsorbent followed by derivatization for the determination of trace concentrations of C3–C18 aliphatic carboxylic acids by gas chromatography with mass spectrometric detection. It is shown that, at the distillation stage, 90% of free carboxylic acids of the homologous series are transferred to the distillate, which greatly facilitates the procedure of the analysis of natural water containing impurity particles and humic substances and ensures the achievement of the limit of detection for the analytes about 0.05 μg/L. It is found that, at the SPE stage, the adsorbents based on copolymers of styrene, divinylbenzene, and N-vinylpyrrolidone in plastic cartridges may serve as sources of additional pollution with benzoic, palmitic, and stearic acids in the eluates under investigation
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
Investigation of intermediate oxidation products of Genistein and Luteolin generated in aerobic conditions
Unstable intermediate oxidation products in the solution of Luteolin [L] and Genistein [G] were discovered by HPLC-MS-ESI(-) in aerobic conditions at pH=8. These covalently bonded compounds of [2L-H2] and [L+G-H2] compositions, as well as trimeric [L+2G-2H2], can be separated by the HPLC, but easily undergo further destruction. Possibly, such compounds are products of initial radical oxygenation. In trimeric conjugate Luteolin, as a more potent reducing agent, binds two Genistein molecules together
Investigation of intermediate oxidation products of Genistein and Luteolin generated in aerobic conditions
Unstable intermediate oxidation products in the solution of Luteolin [L] and Genistein [G] were discovered by HPLC-MS-ESI(-) in aerobic conditions at pH=8. These covalently bonded compounds of [2L-H2] and [L+G-H2] compositions, as well as trimeric [L+2G-2H2], can be separated by the HPLC, but easily undergo further destruction. Possibly, such compounds are products of initial radical oxygenation. In trimeric conjugate Luteolin, as a more potent reducing agent, binds two Genistein molecules together
Determination of aliphatic acids in natural waters using distillation and solid-phase extraction
A procedure is developed and conditions are optimized for the pretreatment of natural water using distillation with no prefiltration of acidified water in combination with preconcentration by solid-phase extraction (SPE) on a Strata-X polymeric adsorbent followed by derivatization for the determination of trace concentrations of C3–C18 aliphatic carboxylic acids by gas chromatography with mass spectrometric detection. It is shown that, at the distillation stage, 90% of free carboxylic acids of the homologous series are transferred to the distillate, which greatly facilitates the procedure of the analysis of natural water containing impurity particles and humic substances and ensures the achievement of the limit of detection for the analytes about 0.05 μg/L. It is found that, at the SPE stage, the adsorbents based on copolymers of styrene, divinylbenzene, and N-vinylpyrrolidone in plastic cartridges may serve as sources of additional pollution with benzoic, palmitic, and stearic acids in the eluates under investigation
Analysis of oxygen-containing organic substances of natural water using solid phase extraction of distillates
Analysis of organic acids in natural water samples using by the distillation followed by the SPE procedure at Strata-X and GC-MS of trimethylsilane derivatives. Influence of distillation and elution, as well as a cartridge housing material, on the compounds recovery was discussed. Data on organic acids in some natural samples are provided
Analysis of oxygen-containing organic substances of natural water using solid phase extraction of distillates
Analysis of organic acids in natural water samples using by the distillation followed by the SPE procedure at Strata-X and GC-MS of trimethylsilane derivatives. Influence of distillation and elution, as well as a cartridge housing material, on the compounds recovery was discussed. Data on organic acids in some natural samples are provided