Methodological and Ecological Caveats in Deciphering Plant Volatile Emissions: the Case Study of Tomato Exposed to Herbivory and Resource Limitation

Over recent years, major progress in experimental approaches have bring insights about the ecological functions of volatile organic compounds (VOCs) released by plants. However, deciphering volatile emissions in a methodologically robust and ecologically relevant manner remains a challenging issue. A surge in interest is required to characterize potential blind spots in volatile sampling that could result in dramatic bias in our understanding of VOCs. In parallel, ecologists need to account for various environmental factors in order to address appropriately the sources of variations of VOCs. Here we use two common porous polymers, polydimethylsiloxane (PDMS) and Porapak Q, to collect VOCs released by tomato exposed to herbivory in combination with nitrogen shortage. We dissect two key features of volatile blends, i.e., their composition and their diversity. Upon nitrogen limitation, Porapak Q stresses the up-regulation of a common defensive compound (methyl salicylate), while herbivory induces three terpenes involved in the recruitment of natural enemies of Tuta absoluta (2-carene, ɑ-pinene and β-phellandrene). This study suggests that the combination of resource availability and herbivory governs the differential production of generalist and specific VOCs that are active against a broad spectrum or particular herbivore species, respectively. But PDMS was found unsuitable to observe such patterns in the composition of VOC emissions. Additionally, Porapak Q was found more sensitive than PDMS to track the increase in the diversity of stress-related VOC emissions upon nitrogen limitation. This suggests that plants growing with poor resources release more information in surroundings. We discuss particular implications for tri-trophic-mediated plant defences.

Chemical Profile and Use of the Peat as an Adsorbent for Extraction of Volatile Compounds from Leaves of Geranium (Pelargonium graveolens L’ Herit)

Volatile organic compounds (VOCs) from leaves of geranium (Pelargonium graveolens L’ Herit) were extracted by dynamic headspace using Porapak Q (HSD-P) as adsorbent and peat, a novel adsorbent in the extraction of plant volatiles, analyzed by gas chromatography–mass spectrometry (GC/MS) and gas chromatography–flame ionization (GC/FID), and the results were compared with those obtained by hydrodistillation (HD). The yield volatiles changed with the extraction method. HD was more efficient for extracting linalool (11.19%) and citronellyl formate (9.41%). Citronellol (28.06%), geraniol (38.26%) and 6,9-guaiadiene (9.55%) and geranyl tiglate (8.21%) were the major components identified by dynamic headspace using peat (HSD-T), while citronellol (16.88%), geraniol (13.63%), 6,9-guaiadiene (16.98%) and citronellyl formate (6.95%) were identified by dynamic headspace using Porapak Q (HSD-P). Furthermore, this work showed, for the first time, that in natura peat is useful to extract VOCs from leaves of geranium.

Cорбционные микротрубки как образцы состава летучих органических соединений на примере ромашки аптечной (Chamomilla recutita R.)

Предложено применение сорбционных трубок на основе инъекционных игл, заполненных сорбентами Tenax ТА, Carbopack В, Porapak Q, Haye Sep N, MN-202, со сконцентрированными на них аналитами в качестве образцов состава летучих органических соединений. Оценка проводилась на примере газового экстракта цветков ромашки аптечной. Установлены параметры сорбции летучих органических соединений и сроки хранения сорбционных трубок с аналитами.

Studi Penggunaan Katalis Tembaga Molybdenum Oksida Berpenyangga Silica (CuMoO3/SiO2) Untuk Oksidasi Metana Menjadi Methanol Dan Formaldehida

Studi penggunaan katalis tembaga molybdenum oksida berpenyangga silica (CuMoO3/SiO2) untuk oksidasi parsial metana menjadi methanol dan formaldehida telah dilakukan. Preparasi katalis dilakukan dengan metode impregnasi. Hasil identifikasi dengan XRD menunjukkan bahwa komponen katalis terdiri dari senyawa MoO3, Cu2Odan SiO2. Uji kinerja katalis dilangsungkan dalam reaktor pipa lurus berunggun tetap, beroperasi pada temperature 400, 450 dan 500 0C dan tekanan 1 atm. Produk reaksi dianalisis menggunakan gas kromatografi buatan Shimadzu dengan kolom mole sieve 5A dan porapak Q. Konversi metana tertinggi diperoleh 34,1% menggunakan katalis dengan rasio Cu: Mo 1: 3, temperatur reaksi 400 0C. Perolehan methanol tertinggi 3,4 % dan perolehan formaldehida tertinggi 7,3%.Kata kunci : oksidasi parsial metana, katalis (CuMoO3/SiO2), impregnasi, methanol, formaldehida

Influence of Adsorbent Nature on the Dynamic Headspace Study of Insect Semiochemicals

In chemical ecology studies (insect–insect, insect–plant relationships), it is important to choose the appropriate sampling methods and the correct optimization of sampling by using dynamic systems. In the present work, different adsorbents were evaluated in a dynamic system that presents a stream of purified air flowing through an aeration chamber containing a mixture of volatile organic compounds, mainly insect semiochemicals such as α-pinene, sulcatone, β-linalool, menthone, isomenthone, methyl salicylate, grandlure I, grandlure II, grandlure III, grandlure IV, eugenol, and α-ionone. Traditional adsorbents such as Tenax TA, Porapak Q, Hayesep Q, and activated charcoal were evaluated; further, alternatives such as Porapak Rxn RP, HLB, SCX, and silica gel, among others were proposed owing to their lower cost. The results demonstrated that Porapak Q and Porapak Rxn RP, despite their different chemical composition, were able to produce similar ratios of compounds to that of the reference solution and, moreover, with the highest recovery yields. However, it is important to emphasize the adsorption selectivity provided by SCX for eugenol and α-ionone. When Porapak Rxn RP was used in the analysis of Eucalyptus globulus volatiles, excellent results were obtained, and these agree with reported data from a hydrodistillation method.

A STUDY ON CARBON ISOTOPE OF CO2 AND CH4 IN WESTERN DIENG PLATEU BY GAS CHROMATOGRAPHY- ISOTOPE RATIO MASS SPECTROMETER (GC-IRMS)

The carbon isotope can be used to evaluate volcanism phenomenon of volcano. The study of carbon isotope of CO2 and CH4 was carried out in western Dieng Plateau by mass-spectrometer. Before analysis, sampel was separated by gas chromatography using a Porapak-Q column and a FID (Flame Ionization Detector) detector. The gas was oxidized by copper oxide at 850oC before being ionized in mass-spectrometer for isotope analysis. The CO2 content in Candradimuka crater (-4.10 O/OO), indicated that the gas may be as volcanic gas. The other CO2 from Sumber and western Gua Jimat, had isotope value of -10.05 and -12.07 O/OO, respectively, indicating contamination from crustal and subduction material. The carbon isotope of CH4 gas from Pancasan village was -63.42 O/OO, that may be categorized as biogenic gas. Keywords: isotope, CO2, CH4, Dieng.

Inverse gas chromatographic characterization of Porapak Q as an extractant of pollutants from aqueous media

The surface of Porapak Q was characterized by inverse gas chromatography (IGC) carried out by the determination of dispersive and specific adsorption components of Porapak Q surface, calculating γsd and -ΔH as parameters, respectively. An interpretation was given based on the chemical structure of Porapak Q. The obtained results were confirmed through the surface Lewis acidity and basicity constants, K a and K b, respectively, correlating well with the determined thermodynamic parameters.