FIGURE 3. Quality control of maxXbond-regenerated columns.

(a) Restored binding capacity after 20 regeneration cycles. Columns A or B were used and regenerated for 20 cycles of plasmid DNA isolation. Regenerated columns are nucleic acid-free. (b,c) Columns C and D were used for the isolation of plasmid X. After regeneration, plasmid Y was purified with the identical columns; the second DNA isolation of sample Y does not contain any traces of the first DNA sample X (b). PCR analysis does not reveal any DNA molecules from the first isolation (c). Before purification of DNA sample Y, columns C and D were treated with RG1 for 24 h and 5 min, respectively. Then, 750 l RG2 were applied to each column. Finally, DNA was eluted in 50 l of elution buffer. Then, 2 l of eluates were subjected to PCR with appropriate primers for insert in X. C1, control with 1 ng plasmid X DNA; 0, no DNA; C2, control with 1 ng plasmid X DNA and 2 l of each eluate after the regeneration of columns C and D.