If cell clumps are present after adding Buffer P2 to your samples when using a QIAGEN Plasmid Purification Kit in combination with LyseBlue Reagent , you have two options: pipet the cell clumps up and down for resuspension transfer any clumps to a separate tube, add Buffer P1 and mix vigorously for resuspension, add Buffer P2 for lysis, and subsequently transfer the lysed material back to combine it with the rest of the original solution Note: Avoid incubation times longer than 5 minutes in Buffer P2 as this will irreversibly denature plasmid DNA