ALOT column preparation

Some methods of ALOT columns preparation were based on generation of alumina layers in aluminum capillaries [51] and on coating the inner walls of... 

Usually ALOT columns can be prepared using dynamic or static coating techniques (classical methods, see, for example, [13, 14]). Static coating places considerable demands on adsorbent sus-... 

Main factors influencing preparation of ALOT columns... 

The static suspension method for preparing adsorption layer open tubular columns (ALOT) was suggested by Haiasz and Horvath [16, 17]. The columns prepared by this method have been successfully used for many separations. Haiasz and Horvath [16] filled stainless steel capillaries (50 m) with stable suspensions of many combinations of solid and liquid stationary phases, then closed the capillaries at one end and passed them through a furnace, where the solvent used to prepare the suspension evaporated through the open end. In this evaporation process the solid part of the suspension was retained on the capillary wall. This method was successfully used by Ettre and coworkers [18, 19] to produce efficient columns (a 45 m column has 57,000 theoretical plates). 

The same method was used for preparing ALOT column with molecular sieves 13 X. Separation of some gases is shown in Fig. 6-18 [22]. C2He and C2 He are completely separated. 

Methods for preparation of SCOT columns are similar to those used for preparation of ALOT columns. Therefore it is interesting, in our opinion, to describe some of those methods. 

Tock and co-workers [101] suggested a very interesting method for preparation of porous silica layers in open tubular columns. This method was worked out for fused silica capillaries used in liquid chromatography. However, in our opinion it is also promising for ALOT columns in gas chromatography. 

Preparation of ALOT Columns by Sorbent Synthesis inside the Capillary Column... 

Tock and co-workers [101] suggested preparation of ALOT column by precipitation of a thick porous silica layer on the inner wall of fused silica capillaries. Precipitation of silica was from polyethoxy-siloxane solution dynamically coated on the inner wall of the capillary. This investigation was carried out for capillary HPLC however, the results are undoubtedly valuable for gas capillary ALOT columns too. 

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