Can I use a QIAfilter Cartridge for purifying large plasmids?
FAQ ID -121

Data from QIAGEN laboratories show that cosmids of up to 45 kb can be purified using the QIAfilter procedure without any detectable DNA shearing (see figure below).

Note: Many large plasmids are present in very low copy number in cells. For very low-copy-number constructs, refer to the special protocol 'Very Low-Copy Plasmid/Cosmid Purification using QIAGEN-tip 100 or QIAGEN-tip 500 in the QIAGEN Plasmid Purification Handbook. For purification of constructs larger than 50 kb (up to 250 kb) we recommend using the QIAGEN Large-Construct Kit.