5 resultados para headspace analysis

em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"


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We report the identification of a potential pheromone for Gnathotrichus materiarius (Fitch) (Col., Scolytidae). The population sex ratio is close to 1:1, and males initiate attacks on host trees. Headspace and hindgut samples from single males showed the presence of the putative pheromone 6-methyl-5-hepten-2-ol, sulcatol. Unmated males released sulcatol for at least 12 days, and ceased producing the pheromone after 20 days. The peak sulcatol release occurred after 2 days. Males cease production of sulcatol 24 h after being paired with females. Single females were unable to initiate galleries, and no sulcatol was detected from their headspace and hindgut samples. The chiral ratio of the pheromone, observed from headspace samples, was 31% (S)-(+)- and 69% (R)-(-)-sulcatol.

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In this paper is reported the use of the chromatographic profiles of volatiles to determine disease markers in plants - in this case, leaves of Eucalyptus globulus contaminated by the necrotroph fungus Teratosphaeria nubilosa. The volatile fraction was isolated by headspace solid phase microextraction (HS-SPME) and analyzed by comprehensive two-dimensional gas chromatography-fast quadrupole mass spectrometry (GC. ×. GC-qMS). For the correlation between the metabolic profile described by the chromatograms and the presence of the infection, unfolded-partial least squares discriminant analysis (U-PLS-DA) with orthogonal signal correction (OSC) were employed. The proposed method was checked to be independent of factors such as the age of the harvested plants. The manipulation of the mathematical model obtained also resulted in graphic representations similar to real chromatograms, which allowed the tentative identification of more than 40 compounds potentially useful as disease biomarkers for this plant/pathogen pair. The proposed methodology can be considered as highly reliable, since the diagnosis is based on the whole chromatographic profile rather than in the detection of a single analyte. © 2013 Elsevier B.V..

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The present study aimed to evaluate the volatiles profile of red mombin (Spondias purpurea) pulp and its powder produced by spray-drying (SD) as an example to show utility of headspace solid-phase microextraction (HS-SPME) in the analysis of parameters such as the quality and stability of fruit products. Volatiles profiles of the pulp were identified by gas chromatography-mass spectrometry (GC-MS), quantified by gas chromatography-flame ionization detector (GC-FID) and compared to the profile of the powder stored at 0, 60 and 120 days in plastic (PP) or laminated packages (LP). The results showed that the technique was able to identify 36 compounds in the red mombin pulp, 17 out of which have been described for the first time in this fruit, showing that red mombin fresh pulp appears to be unique in terms of volatiles composition. However, only 24 compounds were detected in the powder. This decrease is highly correlated (r(2) = 0.99), at least for the majority of compounds, to the degree of volatility of compounds. Furthermore, the powder stored in PP or LP showed no statistical differences in the amounts of its components for a period of 120 days of storage. Finally, this work shows how HS-SPME analysis can be a valuable tool to assess the quality and stability of fruit products.