Knight:Centrifuge desalting/Zeba columns

Overview
This protocol is for doing buffer exchange on small sample volumes (30-130 &mu;L) volumes.

Materials

 * Zeba Desalt Spin Columns, 0.5 ml from Pierce
 * Variable-speed bench-top microcentrifuge
 * 2.0 mL collection tubes
 * Buffer for exchange

Procedure

 * 1) Remove column's bottom closure.
 * 2) Loosen cap.
 * 3) Place column in a 2.0 mL microcentrifuge collection tube.
 * 4) Centrifuge at 1500 x g for 1 minute.
 * 5) *Removes storage solution.
 * 6) Discard storage solution.
 * 7) Mark orientation of column in centrifuge so that the column is placed in the same orientation each time.
 * 8) Add 300 &mu;L Buffer.
 * 9) Centrifuge at 1500 x g for 1 minute.
 * 10) Discard buffer.
 * 11) Add 300 &mu;L Buffer.
 * 12) Centrifuge at 1500 x g for 1 minute.
 * 13) Discard buffer.
 * 14) Add 300 &mu;L Buffer.
 * 15) Centrifuge at 1500 x g for 1 minute.
 * 16) Discard buffer.
 * 17) Add 300 &mu;L Buffer.
 * 18) Centrifuge at 1500 x g for 1 minute.
 * 19) Discard buffer.
 * 20) Move column to new 2.0 mL collection tube.
 * 21) Apply 30-130 &mu;L of sample to top of compact resin bed.
 * 22) *For volumes less than 70 &mu;L, apply 15 &mu;L stacker of ultrapure water or buffer to top of compact resin bed after sample has absorbed to improve sample recovery.
 * 23) Centrifuge at 1500 x g for 1 minute.
 * 24) Discard desalting column.