QIAEX II Gel Extraction Kit

Using the QIAEX II Gel Extraction Kit, 10 ng to 10 µg DNA are recovered efficiently (see figure "Consistent recovery"). The versatile batch procedure can be easily scaled up to a binding capacity of 15 µg using 30 µl QIAEX II suspension.

The QIAEX II Gel Extraction Kit provides silica particles for purifying 60–95% DNA fragments (40 bp – 50 kb). A volume of 10 µl QIAEX II suspension binds up to 5 µg DNA, which is subsequently eluted in 20 µl.

Purification of DNA fragments with the QIAEX II system is based on solubilization of agarose and selective adsorption of nucleic acids onto QIAEX II silica-gel particles in the presence of chaotropic salt. QIAEX II separates DNA from salts, agarose, polyacrylamide, dyes, proteins, and nucleotides without phenol extraction or ethanol precipitation. QIAEX II is effective for any type of agarose in either TAE or TBE buffers.

QIAEX II particles ensure efficient recovery without shearing, even for large DNA fragments. Optimized buffers permit DNA recovery without sodium iodide, which is difficult to remove from DNA samples, and may affect subsequent reactions.

The solubilization and binding buffer used with the QIAEX II system contains a unique pH indicator. A simple color change indicates whether the pH of the binding mixture is optimal for efficient adsorption of DNA to QIAEX II silica particles (see figure "pH indicator dye"). The colored dye also allows easy visualization of any unsolubilized agarose in the binding mixture, ensuring complete solubilization for maximum yield.

QIAEX II silica-gel particles are added to the solubilized gel slice, and the particles collected by a brief centrifugation step (see flowchart "QIAEX II procedure"). After washing, the pure DNA fragment is eluted in 20 µl of Tris buffer or water.

The QIAEX II Gel Extraction Kit provides QIAEX II suspension together with binding and wash buffers, and a comprehensive handbook. QIAEX II Suspension is also sold separately. Protocols are provided for purification of DNA from agarose gels, solutions, and polyacrylamide gels.

DNA purified with the QIAEX II system can be used directly in most applications, including:

Restriction digestion

Labeling

Ligation

PCR