Separation Size exclusion column

Figure 15.5 Separation of Voriconazole and an internal standard by using SEC-HPLC. Adapted from Journal of Chromatography, B 691, D.A. Stopher and R. Gage, Determination of a new antifungal agent, voriconazole, by multidimensional high-perfomiance liquid chromatography with direct plasma injection onto a size exclusion column , pp. 441 -448, copyright 1997, with permission from Elsevier Science.

Chromatographic purification of cross-links. The initial steps of the purification were to separate the cross-links from monomeric amino acids, followed by the separation of individual cross-links. The acid hydrolyzate of demineralized roof powder (13.0 g collagen) was separafed on a size exclusion column fo yield the high molecular weight fractions. 

Chromatographic approaches have been also used to separate nanoparticles from samples coupled to different detectors, such as ICP-MS, MS, DLS. The best known technique for size separation is size exclusion chromatography (SEC). A size exclusion column is packed with porous beads, as the stationary phase, which retain particles, depending on their size and shape. This method has been applied to the size characterization of quantum dots, single-walled carbon nanotubes, and polystyrene nanoparticles [168, 169]. Another approach is hydro-dynamic chromatography (HDC), which separates particles based on their hydro-dynamic radius. HDC has been connected to the most common UV-Vis detector for the size characterization of nanoparticles, colloidal suspensions, and biomolecules [170-172]. 

The determination of the excess isocyanate is more problematic. In one method, toluene diisocyanate (TDI) is vaporized below the decomposition temperature of the prepolymer and analyzed by gas chromatography. A more precise method is useful if a liquid chromatograph is available. The NCO groups are reacted with methanol and the prepolymer is separated into its constituent parts in a size exclusion column. The methanol-capped isocyanates constitute the lowest molecular weight fraction. The isomers of TDI are differentiated by this technique. 

Gardner et al. [9] recognised that because component separations on size exclusion columns with distilled water are affected by chemical physical interactions as well as component molecular size, distilled water size exclusion chromatography will also fractionate dissolved metal forms. These workers interfaced distilled water size exclusion chromatography with inductively coupled argon plasma detection to fractionate and detect dissolved forms of calcium and magnesium in lake and river waters. 

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