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

Abstract

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.

Volatilomics of Natural Products: Whispers from Nature

“…In the same way, as other organisms could be sampled by different methods, almost all animals could be sampled in vivo, but in some cases, tissue extraction could be preferred for guaranteeing detection of less abundant metabolites. Some techniques applied for VOCs analysis from terrestrial arthropods [35][36][37][38][39], aquatic organisms [40][41][42], mammals [43][44][45][46][47][48], birds [49,50], reptiles [51,52], fishes [53], and amphibians [37,38,[54][55][56][57] include headspace-adsorbent traps, polydimethylsiloxane (PDMS) patches, swabs and stir bar sorptive extraction (SBSE).…”

Tools in the Investigation of Volatile Semiochemicals on Insects: From Sampling to Statistical Analysis

“…HayeSep ® porous polymers are considered second-generation materials, with minimal shrinkage and monomer bleed, and are interchangeable with the Porapak ® series for the collection of volatiles [50]. Each material has its own distinctive fabrication and physicochemical characteristics [51]. For instance, Tenax and Porapak (or HayeSep) sorbents share low affinity for polar and low-molecular weight organic compounds and a high affinity for lipophilic to medium-polar compounds and medium-molecular weight organic compounds, but the thermal stability is different (350 °C and 250 °C, respectively), Tenax being more appropriate for thermal desorption [52].…”

“…In the process, the volatile molecules enter into contact with the sorbent material and deposit onto its surface by intermolecular interactions, with strengths that depend on the affinity of the material for the volatile molecules. This method is primarily useful for VOC collection for qualitative purposes; although quantitative analysis can be performed, a calibration curve is required for each compound using appropriate standards for absolute quantification (see more details in Section 3.1.1) [51,54].…”

“…In the first case, the metabolites are desorbed directly from the material with a high efficiency and can be coupled directly to GC, but desorption must be performed quickly and below the decomposition temperature of the sorbent to avoid permanent damage. In solvent desorption, the main advantage is the possibility of storing the dissolved VOCs for ulterior analysis or bioassays, but some of the original compounds can be lost due to solubility in addition to the masking of most volatile VOCs by the solvent [51,54].…”

Impacto del fuego en la defensa de las plantas: Rasgos funcionales y síntesis de metabolitos secundarios en especies leñosas del Chaco semiárido de Argentina

“…Las proporciones de los compuestos se calcularon a partir del área de los picos de cromatografía gaseosa, de manera que la suma de las áreas totales de los picos de interés equivalía a 100%. La cuantificación de los compuestos se realizó empleando cantidades conocidas de compuestos volátiles como patrones externos de alcanos saturados de acuerdo a la metodología propuesta por Rodriguez, Paliza, y Nazareno, (2017). La identificación de los compuestos se realizó en base a la comparación de los tiempos de retención con patrones específicos, empleando el índice de Kovats (KI), el cual compara el comportamiento de retención de un compuesto de interés con el comportamiento de una serie de alcanos de diferente peso molecular (Soto, Moreira, y Pallini, 2011).…”