Multiple headspace-solid-phase microextraction as a powerful tool for the quantitative determination of volatile radiolysis products in a multilayer food packaging material sterilized with γ-radiation.

A method consisting of multiple headspace solid-phase microextraction followed by gas chromatography-mass spectrometry analysis was developed and used to determine the main volatile radiolysis products formed by γ-irradiation of flexible multilayer food packaging samples. The developed method allows the use of solid-phase microextraction in the quantification of compounds from plastic solid samples. A screening of volatiles in the γ-irradiated and non-irradiated films was performed and 29 compounds were identified in the irradiated packaging, 17 of which were absent in the non-irradiated samples. The main volatile radiolysis products identified were: 1,3-di-tert-butylbenzene; 2,6-di-tert-butyl-1,4-benzoquinone; 4-tert-butyl-phenol and the off-odor compounds butanoic acid and valeric acid. These volatile radiolysis compounds were determined with the proposed method and the results are shown and discussed. Solid-liquid extraction and headspace solid-phase microextraction methods were also studied for comparative purposes. The automated solvent-free multiple HSPME technique here presented can be used to quantify the radiolysis compounds in irradiated plastic solid samples in a simple way with the advantages of being free from matrix influence and environmentally friendly.

Comparative study of differentiation levels and valepotriate content of in vitro cultures and regenerated and wild plants of Valeriana edulis ssp.procera.

Valepotriate content levels in samples of in vitro cultures of Valeriana edulis ssp. procera were compared with those of roots and rhizomes of wild plants in the reproductive stage. Rhizomes and roots of regenerated and wild plants showed a similar valepotriate content. The data obtained support the hypothesis that valepotriate production in V. edulis spp. procera is closely related to rhizome and root differentiation. The large-scale propagation of this endangered plant may offer an attractive alternative for its production for medicinal purposes.

[Biochemistry of the evolutive cycle of Triatoma infestans (vinchuca). V. Volatile fatty acids emission]. / Bioquimica del ciclo evolutivo del Triatoma infestans (vinchuca). V. Emision de acidos grasos volatiles.

The composition of the volatile fatty acids emitted by Triatoma infestans of both sexes was studied. They were constituted by a mixture of the acids acetic, propionic, butyric, isobutyric, isovaleric, valeric and traces of isohexanoic and octanoic. Acetic acid was predominant followed by isobutyric and then by propionic acid. The other fatty acids are minor constituents. When acetic acid was discounted, the remaining composition was similar to the volatile fatty acid distribution pattern of Brindley gland. Both sexes showed a similar composition and therefore discard the possibility that they may function as sexual pheromones.