QIAamp DNA Kits

It is strongly advised to follow the recommendations for preparing sample material provided in the corresponding Protocol Sheet to ensure reliable results.

Plasma: It is recommended to perform plasma separation immediately after blood collection when using EDTA or citrate as anticoagulant to prevent the release of genomic DNA into the plasma fraction.

Urine: Because circulating cell-free DNA in non-stabilized urine samples is rapidly degraded after sample collection due to high nuclease activity, eluates may contain no DNA or exhibit low DNA concentration. Therefore, it is recommended to stabilize urine samples. Even when using stabilized urine, it is recommended to perform a centrifugation step immediately after stabilization to prevent the release of genomic DNA from cells. Alternatively, non-stabilized urine samples can be processed immediately after collection and centrifugation using ATL-pretreatment and automated DNA extraction as described in the corresponding Protocol Sheet.

Yes, please follow the User-Developed Protocol 'Detection of Bordetella pertussis DNA by PCR' (QA14). The procedure is for use with the QIAamp DNA Mini Kit.  Please contact Technical Service for this protocol.

Fragments of approximately 200 bp can be isolated with good recovery. Smaller fragments can also be isolated but the recovery will be reduced with decreasing fragment lengths.

Yes, please follow either of the User-Developed Protocols:

• 'Acetyl Cysteine (NALC) treatment of viscous samples' (QA13). This protocol is for use with the QIAamp DNA Mini Kit.
• 'Acetyl Cysteine (NALC) treatment of viscous samples using the DNeasy Blood & Tissue Kit' (DY06).

The expected yield of genomic DNA isolated from bacteria with the DNeasy Blood & Tissue Kit or the QIAamp DNA Mini Kit is approximately 10 ug of DNA per 2x 10⁹ bacterial cells. Note that yields of genomic DNA will vary depending on bacterial strain, quality of the starting material, growing conditions, and the amount of material processed.

Yes, please follow either of the User-Developed Protocols:

• 'Isolation of DNA from soft tissues using the TissueLyser and QIAamp DNA Mini Kit' (QA31), for use with the QIAamp DNA Mini Kit
• Purification of total DNA from soft tissues using the TissueLyser and the DNeasy Blood & Tissue Kit' (DY11), for use with the DNeasy Blood & Tissue Kit

If you have optimized the lysis conditions for a specific sample type, you can lyse the sample in your lysis buffer, and follow the Supplementary Protocol 'Purification of total DNA from crude lysates using the DNeasy Blood & Tissue Kit' (DY15), or the corresponding protocol in the Appendix of the QIAamp DNA Mini Kit and QIAamp DNA Blood Mini Kit Handbook.

The expected DNA yields from different tissues using the QIAamp DNA Mini Kit are as follows:

DNA was purified with QIAamp Kits following standard protocols.

Alcohol precipitation is commonly used for concentrating, desalting, and recovering nucleic acids. Since less alcohol is required for isopropanol precipitation, this is the preferred method for precipitation of DNA from large volumes. In addition, isopropanol precipitation can be performed at room temperature, which minimizes co-precipitation of salt that interferes with downstream applications.

Procedure

1. Adjust the salt concentration, for example, with sodium acetate (0.3 M, pH 5.2, final concentration) or ammonium acetate (2.0–2.5 M, final concentration).
2. Add 0.6–0.7 volumes of room-temperature isopropanol to the DNA solution and mix well.
3. Centrifuge the sample immediately at 10,000–15,000 x g for 15–30 min at 4°C
4. Carefully decant the supernatant without disturbing the pellet.
5. Wash the DNA pellet by adding 1–10 ml (depending on the size of the preparation) of room-temperature 70% ethanol. This removes co-precipitated salt and replaces the isopropanol with the more volatile ethanol, making the DNA easier to redissolve.
6. Centrifuge at 10,000–15,000 x g for 5–15 min at 4°C.
7. Carefully decant the supernatant without disturbing the pellet.
8. Air-dry the pellet for 5–20 min (depending on the size of the pellet).
9. Redissolve the DNA in a suitable buffer.

Tip: Use a buffer with a pH of 7.5–8.0, as DNA does not dissolve easily in acidic buffers. Often distilled water can have an acidic pH. The addition of EDTA protects the DNA from DNase digestion.

Tip: High-molecular-weight DNA, such as genomic DNA, should be redissolved very gently to avoid shearing. If the DNA pellet does not dissolve easily, heat at 55°C for 1–2 h with gentle shaking.

• Add 1/10 volume of 3 M Na-Acetate pH 5.2, and 2 to 2.5 volumes of ice-cold 100% ethanol to the DNA sample
• Mix, and store at -20°C for at least 1 hour to precipitate the DNA
• Recover the precipitated DNA by centrifugation at full speed in a microcentrifuge for 15-20 minutes
• Pour off the ethanol and wash the pellet twice with room-temperature 70% ethanol
• Allow the DNA pellet to air-dry
• resuspend the DNA in a suitable volume of sterile TE buffer or distilled water

QIAGEN Proteinase K is a subtilisin-type protease, which cleaves at the carboxyl side of hydrophobic, aliphatic and aromatic amino acids. It is particularly suitable for short digestion times. It possesses a high specific activity over a wide range of temperatures and pH values with substantially increased activity at higher temperature. Soluble calcium is not essential for enzymatic activity. This means that EDTA, which is used to inhibit Mg2+-dependent enzymes such as nucleases, will not inhibit Proteinase K activity.

QIAGEN Protease is a broad-specificity Serine protease with high activity, cleaving preferentially at neutral and acidic residues. It is an economical alternative to Proteinase K for isolation of native DNA and RNA from a variety of samples.

For more information on activity of QIAGEN Protease and Proteinase K in various buffers please click here.

Efficient DNA isolation requires thorough sample disruption and digestion.

Although the QIAamp and DNeasy procedures requires no mechanical disruption of the tissue sample, the lysis time will be reduced if the sample is ground in liquid nitrogen or mechanically homogenized in advance. For mechanical homogenization, a rotor–stator homogenizer, such as the QIAGEN TissueRuptor, or a bead mill, such as the QIAGEN TissueLyser, can be used.

To improve digestion of tough tissue samples, Proteinase K incubation at 56°C can be performed overnight. DNA yields may be improved by increasing the amount of Proteinase K or by adding additional proteinase K after several hours of digestion.  

QIAGEN Proteinase K is stable for up to 1 year after delivery when stored at room temperature. To prolong the shelf-life of Proteinase K, storage at 2–8°C is recommended.

Yes, we have the following protocols:

• Isolation of genomic DNA from sperm using the QIAamp DNA Mini Kit; protocol 1 (QA03), long procedure
• Isolation of genomic DNA from sperm using the QIAamp DNA Mini Kit; protocol 2 (QA04), short procedure
• Purification of total DNA from animal sperm using the DNeasy Blood and Tissue kit; protocol 1 (DY02), long procedure
• Purification of total DNA from animal sperm using the DNeasy Blood and Tissue kit; protocol 2 (DY03), short procedure
• Purification of DNA from epithelial cells mixed with sperm cells using the QIAamp DNA Micro Kit (QA40).

Yes, we have the following protocols:

• Isolation of genomic DNA from fungi (culture and blood) using the QIAamp DNA Mini Kit (QA09).
• Isolation of genomic DNA from plants and filamentous fungi using the QIAGEN Genomic-tip (QG08).

Small amounts of RNA and DNA may be difficult to measure spectrophotometrically. Fluorometric measurements, or quantitative RT-PCR and PCR are more sensitive and accurate methods to quantify low amounts of RNA or DNA.

Fluorometric measurements are carried out using nucleic acid binding dyes, such as RiboGreen® RNA Quantitation Reagent for RNA, and PicoGreen® DNA Quantitation Reagent for DNA (Molecular Probes, Inc.).

Yes. We have used the QIAamp DNA Blood Mini Kit to purify DNA fragments as small as 168 base pairs. Our product profile for this kit shows a picture of the apoptotic banding pattern obtained after storage of blood samples at 4°C for extended periods of time prior to isolating DNA.

Dedicated QIAcube kits are the RNeasy Mini QIAcube kit, QIAamp DNA Mini QIAcube Kit, the QIAamp DNA Blood Mini QIAcube Kit, and the QIAamp Viral RNA Mini QIAcube Kit.

See: http://www.qiagen.com/Products/Catalog/Automated-Solutions/Sample-Prep/QIAcube#orderinginformation for a virtual demonstration on how to use the QIAcube.

The composition of Buffer AE is:

• 10 mM Tris-Cl
• 0.5 mM EDTA; pH 9.0.

Yes, please follow the User-Developed Protocol 'Purification of genomic DNA from cultured cells using the QIAamp DNA Micro Kit' (QA43).

Note:  The maximum amount of cells that can be used with this protocol has not been thoroughly tested.  However, we would suggest using no more than 1 x 10⁶ cells.

Tissue is more difficult to lyse than cells in a blood sample. Therefore an additional incubation step in buffer ATL containing Proteinase K is included in the Tissue Protocol to achieve complete sample lysis. Blood cells will directly lyse by incubation in Buffer AL containing QIAGEN Protease. Buffer AL is required in both protocols to ensure appropriate conditions for DNA binding to the silica membrane. For further details on the protocols, please refer to the QIAamp DNA Mini and QIAamp DNA Blood Mini Kit Handbook.

QIAGEN Protease is inactivated by incubation at 70°C for 15 minutes.

To our knowledge, Proteinase K cannot be completely heat-inactivated. Even when incubating at 95°C for 10 minutes, some enzymatic activity remains. This will not negatively affect the QIAamp Procedure, since the enzyme will be efficiently removed by the wash steps in the protocols.

Using QIAGEN Genomic-tips

Protocol for DNA cleanup using Genomic-tips can be found in the 'Special Applications' section of the QIAGEN Genomic DNA Handbook.

Using QIAamp DNA Micro kit

Up to 10ug of gDNA can be cleaned using the cleanup protocol in the QIAamp DNA Micro Handbook.

Using Gentra Puregene Reagents

Gentra Puregene Handbook has protocols for removal of proteins and RNA from purified gDNA in Appendix C and Appendix D respectively.

Always dispose of potentially biohazardous solutions according to your institution’s waste-disposal guidelines. Although the lysis and binding buffers in QIAamp, DNeasy, and RNeasy kits contain chaotropic agents that can inactivate some biohazardous material, local regulations dictate the proper way to dispose of biohazards. DO NOT add bleach or acidic solutions directly to the sample-preparation waste. Guanidine hydrochloride in the sample-preparation waste can form highly reactive compounds when combined with bleach.
Please access our Material Safety Data Sheets (MSDS) online for detailed information on the reagents for each respective kit.

EDTA chelates divalent cations which are required for nuclease activity. While the genomic DNA (gDNA) extracted using QIAGEN products, should not have any nuclease activity, it is possible to introduce nucleases during repeated long-term access of the DNA. EDTA helps to prevent any nuclease activity introduced after the genomic DNA extraction procedures.

However, if the gDNA is stored frozen at -20oC or -80oC, nuclease activity is much reduced. It may be possible to leave EDTA out of the storage buffer without negative consequences when samples are kept under these conditions, and when repeated freeze-thaw cycles are avoided.

We do recommend however that gDNA be stored in a neutral to a slightly basic buffered solution (e.g. 10 mM Tris-Cl pH 8.5 to 9.0) to prevent DNA degradation by acid hydrolysis. Note that deionized water mostly has an acidic pH.

Yes, please follow the Supplementary Protocol 'Purification of REPLI-g amplified DNA using the QIAamp DNA Mini Kit' (RG14).