Journal of chromatography. A
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Polyunsaturated fatty acids (PUFAs) play a pivotal role in the biological effects, and are the potential biomarkers for some diseases. However, the structural diversity and similarity, the low concentration, and the interference of high abundant endogenous components challenge the PUFAs profiling. Herein, a novel analytical approach, off-line and on-line solid phase extraction-nano-liquid chromatography-quadrupole-time-of-flight mass spectrometry (off-line and on-line SPE-nano-LC-Q-TOF-MS), was established to monitor the PUFAs. ⋯ Using this method, 51 PUFAs could be separated well and quantified with the limits of quantification between 0.006 and 2.2 pg. Finally, this developed method was applied successfully to simultaneously qualify and quantify the potential biomarkers in the allergic patients. 21 PUFAs including LTB4, 5S-, 11S-, 15S-HETE and 15S-HEPE showed significant differences. Our study indicated that the established method has the potential to sensitively and accurately determine the PUFAs in biological samples.
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A method involving headspace solid-phase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-TOFMS) was developed and optimised to elucidate the volatile composition of the particulate phase fraction of aerosol produced by tobacco heating products (THPs). Three SPME fiber types were studied in terms of extraction capacity and precision measurements. Divinylbenzene polydimethylsiloxane appeared as the most efficient coating for these measurements. ⋯ The major volatile fraction of the headspace contained ketones, alcohols, aldehydes, alicyclic hydrocarbons alkenes, and alkanes. The method was further applied to compare the volatiles from the particulate phase of aerosol composition of THP with that of reference cigarette smoke and showed that the THP produced a less complex chemical mixture. This new method showed good efficiency and precision for the peak areas and peak numbers from the volatile fraction of aerosol particulate phase for both THP and reference cigarettes.
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Instrumental human scent analysis is undoubtedly desirable for many forensic as well medical applications. Most of the previous human scent studies were focused on volatile organic compounds (VOCs) which were analysed by head space solid phase micro-extraction gas chromatography/mass spectrometry (HS-SPME-GC/MS). This method is, however, significantly less sensitive to "heavier" less volatile compounds emitted from the human skin. ⋯ To resolve a lot of very similar molecules, the comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometer (GCxGC-TOFMS) was used to analyse the hexane scent solutions. Using this technique, more than 137 less volatile molecules including organic fatty acids, ketones, aldehydes, simple esters, alcohols, and especially various fatty acid esters with different carbon chains were identified. A considerable number of these molecules were identified in the scent samples for the first time.
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Synthetic cannabinoids, recently used as alternatives to Cannabis sativa, are among the most frequently abused drugs. Identified in 2014, the synthetic cannabinoids N-(1-amino-3-methyl-1-oxobutan-2-yl)-1-(5-fluoropentyl)-1H-indazole-3-carboxamide (5F-AB-PINACA) and methyl [1-(5-fluoropentyl)-1H-indazole-3-carbonyl]-valinate (5F-AMB) are carboxamides composed of 1-(5-fluoropentyl)-1H-indazole-3-carboxylic acid and valine amide/methyl ester. Because of their composition, these molecules have pairs of enantiomers derived from the chiral center of their amino acid structures. ⋯ We synthesized both enantiomers of these compounds and then separated the enantiomers by liquid chromatography-high-resolution mass spectrometry using a column with a chiral stationary phase consisted with amylose tris (3-chloro-4-methylphenylcarbamate). Under the optimized conditions, the enantiomer resolutions were 2.2 and 2.3 for 5F-AB-PINACA and 5F-AMB, respectively. Analysis of 10 herbal samples containing 5F-AB-PINACA and one herbal sample containing 5F-AMB showed that they all contained the (S)-enantiomer, but the (R)-enantiomer was only detected in two samples and at a ratio of less than 20%.
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Ketamine is often used for anesthesia in veterinary medicine. One possible comedication is the sedative α2-agonist medetomidine. Advantages of that combination are the compensation of side effects of the two drugs and the anesthetic-sparing effect of medetomidine. ⋯ Data were analyzed with compartmental pharmacokinetic models which included two compartments for the ketamine and norketamine enantiomers and a single compartment for the DHNK and 6-hydroxynorketamine stereoisomers. Medetomidine showed an effect on the formation and elimination of all metabolites. Stereoselectivities were detected for 6-hydroxynorketamine and DHNK, but not for ketamine and norketamine.