Column preparation dynamic coating

Columns for LLPC are prepared by using solvent evaporation, direct coating, precipitation, or a dynamic coating technique [3], In the solvent-evaporation technique, the nonvolatile hquid stationary phase is dissolved in a volatile solvent and mixed with the dry sup-... 

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. 

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-... 

The procedure for preparation of these columns is not complicated. The columns were precoated with a graphitized carbon black Carbopack A (Sg - 12 m /g). The dynamically deposited carbon black increased the surface area and solid stationary phase wettability and consequently a very uniform coating was obtained [44]. Suspension of graphitized carbon black (GCB) was prepared with 50 mg GCB, 25 ml carbon tetrachloride, 25 ml dichloromethane and then exposed to an ultrasonic bath for about 30 min. Approximately 2 ml of this suspension were made to flow through the capillary four times at high speed (60 cm/s), reversing the flow direction each time and waiting for the solvent... 

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