Column preparation particle deposition

Porous-layer- open tubular (PLOT) and support-coated open tubular (SCOT) columns are prepared by extending the inner surface area of the capillary tube. A layer of particles can be deposited on the surface or the column wall can be chemically treated to create a porous adsorbent layer. Obviously some of the wall-modified open tubular columns discussed in section 2.3.3 could be... 

For wall-coated open tubular (WCOT) columns, the stationary phase covers the inside surface of the column. The film thickness of the stationary phase can vary from 0.05 to 5 pm. It can be simply deposited on the surface, can originate from the reticulation of a polymer on the silica surface or can be bound to the silica through covalent bonds. The surface of the silica is treated before the stationary phase is deposited to avoid problems of wetability, desorption and stability over time. This treatment can involve attack by HC1 at 350 °C or the deposition of a fine coat of alumina particles. Afterward, the stationary phase is either deposited or prepared in situ by polymerisation at the inner surface of the column. Covalent bonding via Si-O—Si-C allows organic compounds to be bound to the silica surface. In the latter case, the columns are particularly stable and can be rinsed periodically allowing them to recover their initial performance. The efficiency of these columns can reach 150000 theoretical plates. 

For the purification of fullerenes from the fullerene oxides the activated alumina and silica can be used. Fulllerene oxides are adsorbed strongly on such adsorbents from solution and the oxides are removed from fullerene samples. For the preparative separation of fullerenes at present activated carbons and graphite are used [11-14], For this purpose silica with the deposited carbon layer [16] can be used also. In this case it is very easily to regulate the pore diameter and specific surface area of adsorbents as well as particle diameter. Such adsorbents is very important for the decreasing of fullerenes loss. On preparative separation of fullerenes on LiChrosorb SI 60 with deposited carbon layer by modified method [15] on glass column first fractions contained quite pure Csq. 

---