QIAfilter Plasmid Kits

The QIAfilter Plasmid Kits combines QIAfilter Cartridges for rapid clearing of bacterial lysates by filtration instead of centrifugation, with proven QIAGEN-tips containing anion-exchange resin for efficient plasmid purification. Yields of up to 10 mg (giga), 2.5 mg (mega), 500 µg (maxi), and 100 µg (midi) transfection-grade, high-copy plasmid DNA are achieved from culture (culture volumes depend on plasmid copy number, size of insert, host strain, and culture medium).

For purification of low-copy plasmids and cosmids, QIAfilter Plasmid Mega Kits are a better choice than QIAfilter Plasmid Giga Kits, due to the large culture volumes required and the limited capacity of the QIAfilter Mega-Giga Cartridge.

QIAfilter Cartridges, provided in QIAfilter, HiSpeed, and EndoFree Plasmid Kits, are special filter units designed to replace centrifugation following alkaline lysis of bacterial cells. QIAfilter Cartridges completely remove SDS precipitates and clear bacterial lysates in a fraction of the time needed for centrifugation, reducing plasmid-purification time by up to 1 hour.

QIAfilter Mega-Giga Cartridges operate with house vacuum to efficiently clear even large volumes of bacterial lysate with minimal effort. QIAfilter Mega and Midi Cartridges have a syringe format and lysates are cleared rapidly by pushing the liquid through the filter.

The unique anion-exchange resin in QIAGEN-tips is developed exclusively for the purification of nucleic acids. Its exceptional separation properties result in DNA purity equivalent or superior to that obtained by two successive rounds of CsCl gradient centrifugation. Prepacked QIAGEN-tips operate by gravity flow and never run dry, minimizing the hands-on time required for plasmid preparation. The entire QIAGEN plasmid purification system avoids the use of toxic substances such as phenol, chloroform, ethidium bromide, and CsCl, minimizing hazard both to the user and the environment.

Neutralized bacterial lysates are incubated directly in the QIAfilter Cartridge and cleared rapidly by filtration. The cleared lysate is then loaded onto the anion-exchange tip where plasmid DNA selectively binds under appropriate low-salt and pH conditions. RNA, proteins, metabolites, and other low-molecular-weight impurities are removed by a medium-salt wash, and ultrapure plasmid DNA is eluted in high-salt buffer (see flowchart "QIAGEN Plasmid Kit procedures"). The DNA is concentrated and desalted by isopropanol precipitation and collected by centrifugation.

DNA obtained with QIAfilter Plasmid Kits provides excellent results in all applications, from cloning to transfection.