After oligonucleotide synthesis was done, the solid support should be removed quantitatively. At this deprotection step, higher concentrated aqueous ammonium solution is employed. And purification process is also important in order to obtain pure material easily. Since several types of by-products are generated during reactions, Cartridge purification method using column is very popular for it. Several types of eluent and buffer solution are available from FUJIFILM Wako.