Dual Ovenables

Dry column chromatography 494 Dry packing, columns (LC) 349 Dry test meter 843 Dual oven (GC) 62 Durapak phases (GC) 125 Dwell time, gradient elution, (LC) 489, 563... 

Figure 8.18 Schenatic diagram of a dual oven two-dimensional gas chromatograph employing live switching between two capillary columns. (Reproduced with permission from Siemens AG).

Polyethylene terephthalate) (PET) has become a major synthetic polymer during the past forty years. Significant commercial markets [1] have been developed for its application in textile and industrial fibers, films, and foamed articles, containers for carbonated beverages, water and other liquids, and thermoformed applications (e.g. dual ovenable containers). 

Fibre optics components, fibre optics connectors. .. Dual oven cookware, ovenware. .. 

Resins are used in electromc/electncal applications (connectors, circuit boards that are vapor and wave solderable, microwave transparent radomes, integrated circuit chip carriers, miniature switches, explosion proof enclosures, lamp reflectors, and high-precision fiber optic components). Polyetherimide is used for medical components (hat require all forms of sterilization. Other uses are found in the transportation field, dual-ovenable cookware, as well as bearings, fasteners, and advanced composites. 

GRAMSHAW, J.W., VANDENBURG, HJ. and LAKIN, R.A., 1995, Identification of potential migrants from samples of dual-ovenable plastics. Food Additives and Contaminants, 12, 211-222. 

Figure 12.18 shows a typical chromatogram obtained from an on-line product gas analysis for the oxidation of CH4. The chromatograms obtained from the TCD were typically characterized by steady baselines with well-resolved peaks. The product spectrum indicates that both partial and total combustion reactions of CH4 are present. Both CO2 and H2O are baseline-resolved using a Hayesep R column while the O2, N2, CH4, and CO are baseline-resolved on a molecular sieve column. The overall analysis time requires about 9 min. Some gaps exist in the retention times for the various components, but no attempt was made to reduce these by additional optimization of the temperature program. The overall analysis time could have been reduced if the dual-oven method had been used as described elsewhere (Delaney and Mills, 1999 Nicole et al., 2000). 

Delaney, T. M., Mills, P. L. Multidimensional process gas chromatography based on a single GC with dual ovens . Presented at 38th Annual Eastern Analytical Symposium, Somerset, N),... 

Dual ovenable containers must be able to perform under freezable conditions as well as in both microwave and conventional ovens. Materials commonly used for dual ovenables are temperature-resistant plastics such as crystallized PET (CPET), thermoset polyesters, and polycarbonate. CPET, the dominant material, has a temperature stability up to 232°C. 

Most plastics used in dual ovenables are two to six times more expensive than the aluminum containers they replace in frozen food applications. Less expensive plastic containers are made of molded fiber and polyester and paper laminates. However, due to the popularity of the microwave oven, in many cases microwaveable-only containers, instead of dual ovenables, are used. For example, Campbell uses a polypropylene microwaveable-only container for its Soup du Jour, thereby reducing the material costs considerably. 

With the increase in the market of dual-ovenable and microwaveable trays there has been an increase in the demand for special lidding material, as the lid has to provide an oxygen barrier and a 100% hermetic steal to prevent food spoilage, besides being easy to remove. Grades of Du Pout s Mylar OL polyester lidding can be used to seal CPET, thermoset polyesters, and paper-board trays. 

DFMA design for manufacmrability/ assembly DOT dual-ovenable tray... 

Oven with shaking platform, e.g., Hybaid Midi-Dual oven. 

Formed multilayer barrier packages, eg, trays, bowls, and cans from coextruded PP/PVDC/ PP, are being developed for soups and entrees that can be stored at ambient temperatures and heated to serving temperature in a microwave oven. Coextrusions of high performance, high temperature polymers, such as polyether-imide and polysulfone, for dual-oven containers capable of withstanding conventional bake-oven temperatures of 204-232°C are being tested. 

Siemens SiChromat 1- 4 (single oven) SiChromat 2- 8 (dual oven) for multidimensional GC Yes Yes EID ECD ETD EPD TCD Helium detector 1. Liquid-liquid packed columns 2. Split-splitless 3. Temperature programmable 4. On-column 5. Liquid injector valve on-line 6. Gas injection valve 7. Rotary as injection valve No No Yes Yes - Yes/Yes No... 

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