A series of di-/trinitroxide esters and amides featuring PROXYL and/or TEMPO radicals connected with alicyclic bridges were prepared in 61-92 % yields and their properties were analysed by using multiple experimental techniques. The examination of EPR spectra of radicals in organic solvents augmented with DFT calculations brought valuable information on the conformational dynamics and spin exchange mechanisms. Cyclic voltammetry investigations revealed (quasi)reversible electrochemical behaviour of studied nitroxides with their half-wave potentials ranging from -51 to -17 mV. SQUID measurements of selected radicals revealed that the magnetism of di- and trinitroxides is significantly different, since antiferromagnetic coupling in biradicals is notably larger than in triradicals. The single-crystal X-ray analysis of selected biradicals revealed the existence of 3D supramolecular networks of molecules linked through hydrogen-bonding interactions. These polynitroxide radicals can serve as promising bridging or chelating ligands in the synthesis of transition-metal-based molecular magnets.
- Klíčová slova
- electrochemistry, magnetism, nitroxides, radicals, spectroscopy,
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
According to the EU legislation, ochratoxin A contamination is controlled in wines. Tokaj wine is a special type of sweet wine produced from botrytized grapes infected by "noble rot" Botrytis cinerea. Although a high contamination was reported in sweet wines and noble rot grapes could be susceptible to coinfection with other fungi, including ochratoxigenic species, no screening of Tokaj wines for mycotoxin contamination has been carried out so far. Therefore, we developed an analytical method for the determination of ochratoxin A (OTA) and ochratoxin B (OTB) involving online SPE coupled to HPLC-FD using column switching to achieve the fast and sensitive control of mycotoxin contamination. The method was validated with recoveries ranging from 91.6% to 99.1% with an RSD less than 2%. The limits of quantification were 0.1 and 0.2 µg L-1 for OTA and OTB, respectively. The total analysis time of the online SPE-HPLC-FD method was a mere 6 min. This high throughput enables routine analysis. Finally, we carried out an extensive investigation of the ochratoxin contamination in 59 Slovak Tokaj wines of 1959-2017 vintage. Only a few positives were detected. The OTA content in most of the checked wines did not exceed the EU maximum tolerable limit of 2 µg L-1, indicating a good quality of winegrowing and storing.
- Klíčová slova
- Tokaj wine, chromatography, column switching, food control, mycotoxin, ochratoxin A, ochratoxin B, online extraction,
- MeSH
- analýza potravin metody MeSH
- chromatografie kapalinová MeSH
- extrakce na pevné fázi MeSH
- kontaminace potravin analýza MeSH
- ochratoxiny analýza MeSH
- řízení kvality MeSH
- senzitivita a specificita MeSH
- víno analýza MeSH
- Vitis chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- ochratoxin A MeSH Prohlížeč
- ochratoxin B MeSH Prohlížeč
- ochratoxiny MeSH
Nowadays, fingerprinting of food became one of the most perspective analytical tools to resolve a problem of food quality and authentication, especially in difficult cases like differentiation of fruit varieties. In this work, plum brandies distillated by the same technology from 25 plum cultivars were distinguished by comprehensive two-dimensional gas chromatographic analysis and sensory evaluation. The number of identified compounds in studied samples varied between 91 and 195 depending on the plum variety. Enriched volatile organic compounds (VOC) profile was identified for the samples received from "Chrudimer", "Cacak Fruitful" and "Hanita" plum varieties, whereas in the case of "Gabrovská", "Presenta", Elena" and "President" plum varieties, the VOC profile was significantly reduced. From qualitative point of view, the particular plum brandies showed differences in the presence of unsaturated fusel alcohols (e.g. 3-methyl-3-buten-1-ol, trans-3-hexenol), unsaturated aldehydes (2-butenal, 2-nonenal), monoterpene derivatives (e.g. linalool acetate, geraniol acetate) and lactones, which were mainly detected at the trace level.
- Klíčová slova
- Comprehensive two-dimensional gas chromatography, GCxGC–TOF-MS, Plum brandy, Plum cultivar, Sensory analysis,
- Publikační typ
- časopisecké články MeSH
A total of 196 out of 209 polychlorobiphenyl (PCB) congeners were resolved using GC×GC-TOFMS with a non-polar/ionic liquid column series consisting of poly(50%-n-octyl-50%-methyl)siloxane and (1,12-di(tripropylphosphonium)dodecane bis(trifluoromethansulfonyl)amide) in the first and second dimension, respectively. It has been found that 13 PCB congeners overlap in five doublets (CB12+CB13, CB62+CB75, CB70+CB76, CB97+CB125 and CB153+CB168) and one triplet (CB90+CB101+CB113). All toxic, "dioxin like" congeners were separated with no interferences from any PCB congener. The 109 PCBs present in Aroclor 1242 and the 82 PCBs present in Aroclor 1260 were resolved GC×GC-TOFMS analysis on this column set.
- MeSH
- iontové kapaliny chemie MeSH
- plynová chromatografie s hmotnostně spektrometrickou detekcí metody MeSH
- polychlorované bifenyly chemie izolace a purifikace MeSH
- siloxany chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- iontové kapaliny MeSH
- polychlorované bifenyly MeSH
- siloxany MeSH
