Anionic Weak and Strong

Weak anionic exchangers use bonded phases with either primary, secondary, or tertiary amines as the function exchanger. It forms weaker bonds with strong anions and is cleanable by going to high pH using a saturation column to form the free amine form of the anion exchanger. 

Weak amine columns, whether primary, secondary, or tertiary, will all oxidize in solvents containing dissolved oxygen and need to be protected by nitrogen-purged vacuum-treated solvents as mentioned in Chapter 6. It may seem inconvenient, but column life will be 3 months or less without it. 

Both cationic and anionic silica columns need occasionally to be repaired. If you have the same packing material as the column, make a paste of it with mobile phase and paste it on to the column head. If the same packing is unavailable, use cyanopropyl packing for small repairs. If necessary, these columns can be washed with water, then with 20% DMSO/MeOH, with water, and, finally, reequilibrated with buffer. 

Do not try to open or repack polymeric columns. They are usually under some pressure and come out of the tube like toothpaste. The column is of no use. Polymeric columns are usually packed in one solvent, then switched to a second solvent, which causes the packing to swell and squeeze out voids. They are then designed to be run in the second solvent. Polymeric ion exchangers are usually run at elevated temperature. This serves two purposes it decreases mobile phase viscosity, thereby reducing operating pressures, and it speeds 

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Strongly retained anions weak and strong acid anions separated in one run resolves acetate and formate away from fluoride and chloride... 

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