Why doesn't the eluted DNA perform well in downstream applications?"

(1) Residual ethanol contamination: After the wash step, dry the PD Column with additional centrifugation at full speed for 5 minutes or incubate at 60°C for 5 minutes. (2) RNA contamination: Prior to using PD1 Buffer, ensure that RNase A was added. If RNase A added PD1 Buffer is out of date, add additional RNase A. (4) Too many bacterial cells were used: reduce sample volume. (5) Genomic DNA contamination: Do not use overgrown bacterial cultures. During PD2 and PD3 Buffer addition, mix gently to prevent genomic DNA shearing. (6) RNA contamination: Prior to using PM1 Buffer, check that RNase A was added. If RNase A added PM1 Buffer is out of date, add additional RNase A. (7) Too many bacterial cells were used: Reduce sample volume. (8) Genomic DNA contamination: Do not use overgrown bacterial culture samples. During the PM2 and PM3 Buffer addition steps mix solution gently to prevent genomic DNA shearing.