Supercritical fluid chromatography oligomers

The use of separation techniques, such as gel permeation and high pressure Hquid chromatography interfaced with sensitive, silicon-specific aas or ICP detectors, has been particularly advantageous for the analysis of siUcones in environmental extracts (469,483—486). Supercritical fluid chromatography coupled with various detection devices is effective for the separation of siUcone oligomers that have molecular weights less than 3000 Da. Time-of-flight secondary ion mass spectrometry (TOF-sims) is appHcable up to 10,000 Da (487). 

Cyclopentadiene oligomers up to octamers can be effectively analy2ed and quantified by supercritical fluid chromatography using a chemically bonded methyl siUcone capillary column. 

Supercritical fluid chromatography (SFC) is a GC method of analysis of compounds in systems where normal GC presents resolution difficulties (Lee and Markides, 1987). A supercritical fluid has properties at a critical temperature intermediate between a liquid and a gas. At and above this critical temperature, a gas cannot be compressed into a liquid, irrespective of the pressure, but it solvates solid matter as if it were a liquid. A supercritical fluid diffuses freely into and out of adsorbent pores with a minimum of resistance. A major advantage of SFC chromatography is its ability to effect separation of oligomers without derivatization. 

Prior to the commercialisation of LC-MS instruments, supercritical fluid chromatography (SFC) was mainly used for the analysis of oligomers. As the range of LC-MS instruments can be extended up to 4000 dal tons this capability makes them ideal to characterise oligomers. For example, it has been shown that silicone oligomers can be detected by LC-MS in food simulants. ... 

Klesper, E., and W. Hartmann. 1977. Supercritical fluid chromatography of styrene oligomers. Polym. Lett. 15 9. 

Hagenhoff, B., Benninghoven, A., Barthel, H., and Zoller, W., Supercritical fluid chromatography and time-of-flight secondary ion mass spectrometry of poly(dimethylsiloxane) oligomers in the mass range 1000-10,000 Da. Ana/. Chem., 63, 2466, 1991. 

Chromatography with a supercritical fluid as mobile phase was first reported more than twenty years ago [1], although only in recent years have its advantages been realized. These are especially relevant to oligomers, polymers, and polymer additives, and supercritical fluid chromatography (SFC) is finding increasing use in analyses in polymer chemistry. 

Hagen, H.M., Landmark, K.E., and Greibrokk, T. (1991) Separation of oligomers of polyethylene glycols by supercritical fluid chromatography. Journal of Microcolumn Separations, 3, 27. 

Supercritical fluid chromatography combined with time of flight mass spectrometry has been used to determine the molecular weight distribution of poly(dimethylsiloxane) oligomers in the mass range 10 to 10. ... 

The third category of supercritical fluid-polymer activity reported in the literature describes the use of SCF chromatography to separate oligomers. The classic paper in this field is by Jentoft and Gouw (1969), who reported their work on the supercritical fluid chromatographic separation of a monodis-perse polystyrene. Jentoft and Gouw use the quotation marks because, as they report later in the article, the polystyrene sample that they tested... 

Fractionation of a polymer into its separate oligomers, as reported by Jentoft and Gouw, is an impressive achievement for supercritical fluid solvents. However, in general it is achieved only in conjunction with chromatography with materials processed at microgram to milligram levels. Supercritical fluid... 

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