The role of flavor and fragrance chemicals in TRPA1 (transient receptor potential cation channel, member A1) activity associated with allergies

TRPA1 has been proposed to be associated with diverse sensory allergic reactions, including thermal (cold) nociception, hearing and allergic inflammatory conditions. Some naturally occurring compounds are known to activate TRPA1 by forming a Michael addition product with a cysteine residue of TRPA1 through covalent protein modification and, in consequence, to cause allergic reactions. The anti-allergic property of TRPA1 agonists may be due to the activation and subsequent desensitization of TRPA1 expressed in sensory neurons. In this review, naturally occurring TRPA1 antagonists, such as camphor, 1,8-cineole, menthol, borneol, fenchyl alcohol and 2-methylisoborneol, and TRPA1 agonists, including thymol, carvacrol, 1’S-1’- acetoxychavicol acetate, cinnamaldehyde, α-n-hexyl cinnamic aldehyde and thymoquinone as well as isothiocyanates and sulfides are discussed

Detailed elucidation of hydrocarbon contamination in food products by using solid-phase extraction and comprehensive gas chromatography with dual detection

The present work is focused on the development/optimization of a comprehensive two-dimensional gas chromatography method, with dual detection [flame ionization (FID) and mass spectrometric], for the simultaneous identification and quantification of mineral-oil contaminants in a variety of food products. The two main classes of contaminants, namely saturated and aromatic hydrocarbons, were previously fractionated on a manually-packed silver silica solid-phase extraction (SPE) cartridge. The quantitative results were compared with those obtained by performing a large volume injection, in a GC-FID system, after the same SPE process and by an on-line liquid\u2013gas chromatography method, with very similar results observed. The presence of a series of unknown compounds, that appeared when using the off-line methods, was investigated using the mass spectrometric data, and were tentatively-identified as esterified fatty acids, most probably derived from vegetable oil based in

A flexible loop-type flow modulator for comprehensive two-dimensional gas chromatography

The present investigation is focused on a simple flow modulator (FM), for comprehensive twodimensional gas chromatography (GC 7GC). The interface is stable at high temperatures, and consists of a metallic disc (located inside the GC oven) with seven ports, which are connected to an auxiliary pressure source via two branches, to the first and second dimension, to a waste branch (linked to a needle valve) and to an exchangeable modulation loop (2 ports). The ports are connected via micro-channels, etched on one of the inner surfaces of the disc. Modulation is achieved using a two-way electrovalve, connected on one side to the additional pressure source, and to the two metal branches, on the other. An FM enantio-GC 7polar-GC method (using a flame ionization detector) was optimized (a 40-L loop was employed), for the analysis of essential oils. As an example, an application on spearmint oil is shown; the method herein proposed was subjected to validation. Finally, an FM GC 7GC diesel experiment was carried out, using an apolar\u2013polar column combination, to demonstrate the effectiveness of the modulator in the analysis of a totally different sample-type

Characterization of bacterial lipid profiles by using rapid sample preparation and fast comprehensive two-dimensional gas chromatography in combination with mass spectrometry

The bacteria fatty acid profile has been extensively studied for taxonomic classification purposes, since bacteria, in general, contain particular and rare fatty acids, compared with animal and plant tissues. As for any real-world sample type, the development of rapid and reliable methods for (i) sample identification (in this case, bacterium type), and (ii) constituent identification (in this instance, the fatty acid profile) is desirable. In this research, a half-an-hour procedure, to analyze bacteria, was developed: a 2-min one-step sample preparation step was followed by a relatively fast comprehensive 2D GC-MS separation (25 min). Furthermore, dedicated MS libraries were constructed for the iden- tification of bacteria and fatty acids. Finally, data processing, only qualitative at this stage, was carried out with the support of a novel comprehensive 2D GC software

Performance evaluaton of a rapid scanning quadrupole mass spectrometer in the comprehensive two dimensional chromatography analysis of drinking water pesticides

The performance of a novel rapid-scanning (20\u2009000\u2009amu/s) quadrupole mass spectrometer (qMS) has been evaluated in the comprehensive 2-D gas chromatography (GC 7GC) analysis of pesticides contained in water. Analyte extraction was performed by using direct solid-phase microextraction (SPME). The MS system was operated using a rather wide m/z 50\u2013450 mass range and a 33\u2009Hz spectral production rate, a frequency which was found sufficient for reliable quantification. The qMS performance was evaluated considering: (i) number of data points per peak, (ii) mass spectral quality, (iii) extent of peak skewing, and (iv) consistency of retention times. Seven-point calibration curves (external calibration) were constructed for 28 pesticides over the limit of quantification range of 100\u2009\u3bcg/L (1, 5, 10, 25, 50, and 100\u2009\u3bcg/L). The solid-phase microextraction-GC 7GC-qMS method was validated by calculating limits of detection and quantification, intraday peak area precision, accuracy, and intraday retention-time precision. A series of tap water samples were subjected to analysis, fortunately giving negative results