Polyethylene Glycol Phases

The most widely used non-silicon-containing stationary phases are the polyethylene glycols. They are commercially available in a wide range of molecular weights under several designations, such as Carbowax 20M and Superox-4. The general structure of a polyethylene glycol may be described as 

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An aqueous biphasic system consisting of two immiscible liquid phases (i.e., two separate distinct layers) can be used to separate a particular component such as certain heavy metals from contaminated soil. A combination of phases such as a water-soluble polymer (e.g., polyethylene glycol) phase and a concentrated aqueous salt solution (e.g., sodium carbonate, sodium sulfate, or sodium phosphate) phase can comprise a biphasic system. Aqueous biphasic systems are... 

Keywords Carbon dioxide Polyethylene glycol Phase behavior Biphasic solvent system Supercritical fluids Phase equilibrium... 

Gas Chromatography-Mass Spectrometry. A VG Trio-2 mass spectrometer was directly coupled with the Hewlett-Packard 589 R gas chromatograph, equipped with a 30 m x 0.32 mm DB-WAX capillary column (J and W. Scientific bonded polyethylene glycol phase). The carrier gas was He at 2.3 ml/min. The injector and transfer temperature was programmed as follows 30 C (2 min isothermal), to 38°C at l°C/min, then to 180°C at 2°C/min. The instrument was operated in the electron-impact mode at an ionization voltage of 70eV. Quantitative analysis by peak area, plots of chromatograms, and library search results were obtained. 

Two types of stationary phases are most popular the polysiloxanes and polyethylene glycol phases. Both types of phases may be characterized as having the necessary high viscosity and the capability for crosslinking and/or chemical bonding with fused silica. One should note the presence of more recent additions to the capillary column family, namely, specialty columns designed for selected EPA methods, chiral separations, and gas-solid chromatographic separations. These specialty phases are considered in Section 3.11.6. 

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