Column preparation leaching

During the drawing process the fused silica is subject to a range of temperatures resulting in a surface with an undefined silanol concentration that is also likely contaminated by trapped acidic impurities. Conditioning and hydrothermal treatment (acid leaching) are generally required to remove acid impurities and provide a uniform and defined silanol concentration for column preparation. These procedures are usually performed in the laboratory and are essential to minimize batch-to-batch variation in column properties. 

Analytical Properties Separation of bopindolol and also separation of pindolol after derivatization with isopropyl isocyanate separation of dl mixtures of enantiomers can be used on both the analytical and preparative scales changes in pH will cause this phase to leach from the column storage at 4°C is recommended Reference 1,2... 

Beads are made of glass with a high boron content that then is leached away by acids to make them porous. These come in various sizes, but a popular size is about 50 pm in diameter. They have very large surface areas - 300 to 500 mVg. This large area means a high column capacity, so these materials are used for preparative separations. The retention times are longer, because the diffusion distances (19 pm in and 19 pm out) can be long. 

Normal superphosphate or triple superphosphate (common commercial fertilizers) are cheap sources of water-soluble phosphate. Normal superphosphate is primarily a mixture of monocalcium phosphate and calcium sulfate (gypsum), while triple superphosphate is essentially all monocalcium phosphate. Monosodium phosphate was prepared from superphosphate by first leaching superphosphate with sea water until a saturated solution of monocalcium phosphate was obtained. Then the monocalcium phosphate solution in sea water was percolated through a column of Dowex 50 (strongly acidic type resin) in the sodium form. The effluent from the column was a solution of monosodium phosphate in sea water and the resin was converted to the calcium form as shown by Equation 6. 

The feed solution is prepared by acid leaching, removal of gross solids by filtration or counter-current decantation, together with a final polishing filtration step, often in a sand-bed clarifier. Using such a feed, a typical cycle of operations for a four-column system with split elution is as follows ... 

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