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Sample Preparation Techniques to Isolate and Recover Organics and Inorganics
Published in Paul R. Loconto, Trace Environmental Quantitative Analysis, 2020
It is recommended that 1 cm of methyl silicone-coated packing be inserted at the inlet to extend the life of the trap. Method 5030B from the SW-846 series is more specific than Method 502.2 and recommends a 3% OV-1 on Chromosorb-W, 60/80 mesh, or equivalent. Analysts who do not need to quantitate dichlorodifluoromethane do not need to use the charcoal and can replace this charcoal with more Tenax. If only analytes whose boiling points are above 35°C are to be determined, both the charcoal and the silica gel can be eliminated and replaced with Tenax. The trap needs to be conditioned at 180°C prior to use and vented to the atmosphere instead of the analytical GC column. It is also recommended that the trap be reconditioned on a daily basis at the same temperature. Tenax is a unique polymer and offers the advantage that water is not trapped to any great extent.
Medium Density Fiberboard as Food Contact Material
Published in Sanjay Mavinkere Rangappa, Parameswaranpillai Jyotishkumar, Senthil Muthu Kumar Thiagamani, Senthilkumar Krishnasamy, Suchart Siengchin, Food Packaging, 2020
P. Vazquez-Loureiro, F. Salgado, A. Rodríguez Bernaldo de Quirós, R. Sendón
Tenax® (polyoxide of 2,6-diphenyl-p-phenylene, MPPO) is a polymer of high porosity and specific surface, which is commonly used as an adsorbent of volatile compounds and as food simulant. It has own characteristics such as particle size: 60–80 mesh, pore 200 nm and high price. Moreover, it is difficult to handle, and after the migration tests, substances must be extracted prior to its analysis. In order to carry out the migration assays with Tenax, at the conditions cited above, the following experimental conditions are proposed: approx. 1 g of Tenax is homogenously distributed over a 5 × 5 cm MDF sample using a glass ring; this sample is placed in a Petri dish and at the same time it is placed inside a container where a solution is at the bottom for RH control. Figure 13.6 shows an example. After 10 days, all selected compounds trapped into Tenax need to be extracted before its determination. Extraction conditions will depend on the substance and also on the final analytical technique selected.
Introduction
Published in R. A. Jenkins, M. R. Guerin, B. A. Tomkins, The Chemistry of Environmental Tobacco Smoke, 2000
R. A. Jenkins, M. R. Guerin, B. A. Tomkins
For non-ETS-specific indoor air studies, Tenax appears to be the most popular sorbent (Wallace 1987). Tenax is a porous polymer resin originally developed for use as a gas-solid chromatographic stationary phase. It received wide use in air-sampling applications, probably because it has very good retention characteristics for the C7 through C12 compounds, does not retain water, and can be reused repeatedly. However, it must undergo extensive cleanup prior to initial use and is subject to decomposition through reaction with atmospheric ozone or oxides of nitrogen (Pellizzari et al. 1984). It can be used in small traps for experiments of limited duration, and quantities as large as 2.5 g can be packed into large tubes for 24-h air-sampling experiments (Jenkins et al. 1982). The chief disadvantages of Tenax are its poorer retention of more-volatile species and its propensity to release self-decomposition products during higher-temperature thermal desorption analysis. At long sampling times, breakthrough of the more volatile constituents can occur. In order to compensate for this deficiency, Tenax has been combined in sequence with other more retentive sorbents in order to determine the more-volatile ETS constituents quantitatively (e.g., Higgins et al. 1988). Breakthrough volumes under various sampling conditions for many constituents have been compiled by the U.S. Environmental Protection Agency (EPA) (Gallant et al. 1978).
Investigation and preparation of biodegradable starch-based nanofilms for potential use of curcumin and garlic in food packaging applications
Published in Journal of Biomaterials Science, Polymer Edition, 2020
To determine the suitability of plastic substances and materials that contact or may contact foods, migration analyses are carried out. Necessary preparations were made by utilizing the Turkish Standard European Norm (TS EN) 1186-1 standard, and a suitable method for the material was selected. As the first step, appropriate simulant selection was made by considering which foods the product would contact Turkish Food Codex (TGK) 2013/34.95% ethanol and isooctane; simulants imitating fatty foods,50% ethanol; simulant imitating milk and milk products,10% ethanol; simulant imitating liquid foods,3% acetic acid; simulant imitating acidic foods,Tenax; simulant imitating dry foods. Tenax is a porous polymer resin based on 2,6-diphenyl-p-diphenylene oxide. It is used especially for environmental sampling. It has been specifically designed for the trapping of volatiles and semi-volatiles from air or which have been purged from liquid or solid sample matrices. Tenax can be used to collect organic bases, neutral compounds, and high-boiling compounds. The polymer is of particularly used for concentration of high boiling compounds such as alcohols, polyethylene glycols, phenols, monoamines and diamines, ethanol amines, amides, aldehydes, ketones and chlorinated aromatics.