The QIAfilter Plasmid Midi Kit combines QIAfilter Midi cartridges for rapid clearing of bacterial lysates by filtration instead of centrifugation, with proven QIAGEN-tip 100 anion-exchange tips for efficient plasmid purification.
| QIAfilter Plasmid Midi Kit Specifications | |||
| Expected yield* | Column capacity | Culture volume† | QIAfilter format |
| Up to 100 µg | 100 µg | 25–50 ml | Syringe-format Midi Cartridge |
* Actual yields depend on plasmid copy number, size of insert, host strain, culture medium, and culture volume.
† Culture volumes depend on plasmid copy number, size of insert, host strain, and culture medium.
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 Midi Cartridges have a syringe-format (see figure "QIAfilter Midi Cartridge") and lysates are cleared in a matter of seconds 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. Pre-packed 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 in seconds 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 "Comparison of 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 and automated fluorescent sequencing, including capillary sequencing.