To improve the reliability and information content of the quality control of cognacs and cognac spirits and to detect the signs of adulterated products, quality tests and methods for the instrumental analysis of cognacs and brandies by gas chromatography, high-performance liquid chromatography, gas chromatographymass spectrometry, and UV-VIS spectrophotometry are considered. A set of marker substances, the concentrations of and ratios between which allow one to detect various types of adulterations and violations in manufacturing processes, was determined and methodologically substantiated. The marker substances were tentatively subdivided into several groups: volatile components, which are characteristic of cognac and affect its organoleptic properties; oak-wood substances, which are accumulated in cognac spirit in the course of aging; flavoring components; denaturing agents; and other substances that are uncharacteristic of cognac. Particular kinds of cognac products were experimentally examined, and the most characteristic types of adulterations and technological violations in the manufacture of both domestically produced and imported cognac products were exemplified. Recommendations on the effective quality control of cognac products are given, and a high level of identification methods in use is noted.
The concentration levels and distribution features of the platinum group elements (PGE) in quartzsulfide and base-metal ores in deposits of the Sayan-Baikal Fold Region (SBFR) are discussed. Microfire assay neutron activation analysis (MF-NAA), which enables one to work on a nondestructive basis and allows one to avoid inaccuracies related to chemical sample preparation, was used as the main analytical technique. Three types of hydrothermal mineralization with elevated grades of PGE (especially Pt, Pd, and Ru) have been identified: (1) pyrite-pyrrhotite (massive sulfide) mineralization hosted in black shales of the Il'chir Sequence;(2) gold-sulfide ores of the Zun-Kholba, Tainsky, Kamenny, and some other gold deposits; and (3) silver-basemetal ores of the Dzhida-Vitim Zone. The PGE contents significantly vary, from global average values to tens of grams per ton. An absence of PGE minerals implies that these elements are finely dispersed in sulfide minerals and native gold. Taking into account difficulties in conversion of PGE into analytical forms, their nonuniform distribution in sulfide minerals, their high affinity to coordination compounds, and experimental results, cluster species of Pt and Pd in major minerals are suggested for the gold-sulfide and silver-base-metal ores in deposits, which are related to suprasubduction ophiolites and island-arc and intraplate settings in the SBFR.
Abstract-Sychevka is a relatively unweathered 65-kg iron meteorite that was found in Russia in 1988. The microstructure, mineralogy and bulk composition ofSychevka as revealed by optical microscopy, electron microprobe and instrumental neutron activation analysis indicate that this meteorite is a group-IIIAB medium octahedrite. Sychevka consists of (in vol%): kamacite (82.5), plessite (16), schreibersite (1.5), and rare grains of chromite and troilite.
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