MaXtract High Density

For safer and convenient extraction of nucleic acids from organic solvents


  • Safer extraction of nucleic acids from organic solvents
  • Reduced carryover of contaminants
  • High nucleic acid recovery
  • Convenient nucleic acid recovery
MaXtract High Density (200 x 2 ml)

Cat. No. / ID: 129056

200 x 2 ml MaXtract High Density Tubes
200 x 2 ml
200 x 1.5 ml
100 x 15 ml
25 x 50 ml
The MaXtract High Density is intended for molecular biology applications. This product is not intended for the diagnosis, prevention, or treatment of a disease.

Product Details

MaXtract High Density simplifies the extraction of nucleic acids from organic solvents (e.g., phenol/chloroform). The MaXtract gel forms a stable barrier between the organic solvent and the nucleic acid-containing aqueous phase allowing easy recovery of the aqueous phase while preventing carryover of organic solutions, proteins and other contaminants.


MaXtract High Density enables 30% higher recovery compared to traditional extraction methods. Proteins and other contaminants migrate to the organic phase and interphase. The barrier formed by MaXtract High Density gel is sufficiently durable that these contaminants remain trapped below the barrier, preventing carryover when removing the aqueous phase. The aqueous phase can be removed by decanting or pipetting, leading to nucleic acid recoveries that are up to 30% higher than when using traditional organic extraction methods.

MaXtract High Density is provided in a variety of tube sizes, enabling extraction from sample volumes ranging from 100 µl to 20 ml.

Phase separation by MaXtract High Density
Aqueous phase Phenol:chloroform Chloroform
<0.5 M NaCl, <1 mg/ml protein Yes Yes
≥0.5 M NaCl Yes Yes
≥1 mg/ml protein Yes Yes
Plasmid DNA isolation Yes Yes
Genomic DNA isolation Yes Yes
RNA isolation Yes Yes
* Includes phenol:chloroform:isoamyl alcohol.


MaXtract High Density gel provides safe and fast recovery of nucleic acids from organic extractions using solvents such as phenol/chloroform (see flowchart " MaXtract procedure").
See figures


Simply add the nucleic acid solution and organic solvent to the tube containing MaXtract gel. After mixing and centrifugation, MaXtract High Density gel forms a stable barrier, separating the organic and aqueous phases. The barrier safely traps the hazardous organic solvent and contaminants, allowing you to easily decant or pipet the nucleic-acid–containing aqueous phase into a new tube (see figure " Safe and easy nucleic acid extraction"). If a second extraction is necessary, this can be performed in the same tube, provided that the maximum tube volume is not exceeded.

Separation using MaXtract High Density gel relies on density differences between the aqueous and organic media. The organic layer must have a higher density than the gel and the aqueous phase, and the gel must have a higher density than the aqueous phase.

See figures


MaXtract High Density is highly suited for isolation of plasmid DNA, genomic DNA, or RNA. Protocols optimized for specific applications, such as recovery of DNA from low-melting-point agarose, are also available. Nucleic acids extracted using MaXtract High Density gel are suitable for many downstream applications.

Supporting data and figures


Can phenol/chloroform be placed in the MaXtract tube for extraction at a later time?

Yes. The organic phase can be placed in MaXtract Low and High Density tubes without any problem 3-4 hours before preparation of the samples. Make sure to perform the centrifugation step first, so that the gel collects at the bottom of the tube.


FAQ ID -1299
Can MaXtract tubes be autoclaved prior to use?

No. After autoclaving, the MaXtract gel no longer has the same properties. Since the MaXtract tubes are manufactured and filled in a fully automated process, autoclaving is not required.



FAQ ID -1305
Can DNA isolated with MaXtract tubes be used for downstream applications such as restriction digestion, labeling, blotting, PCR, and automated sequencing?

DNA purified by organic extraction can principally be used for these downstream reactions. It should be noted that phenol, like all organic solvents, alters the active centre of enzymes, thus deactivating them. An ethanol precipitation should therefore generally be carried out prior to enzyme controlled downstream reactions. Potential phenol residue is thereby effectively removed.

The use of MaXtract Low and High Density tubes has the advantage that no recontamination of the sample by organic solvents or proteins occurs.


FAQ ID -1303
What factors determine if denatured proteins accumulate underneath, or inside the gel of the MaXtract Low and High Density Tubes?

Generally, this is determined by the density of the denatured proteins and the gel type in the MaXtract Tubes. If proteins show a higher density than the gel, they will accumulate underneath in the organic phase. If they have the same density as the MaXtract gel, they will collect in the gel. The quantity and ratio of phenol:chloroform can also influence the behavior of the proteins.


FAQ ID -1312
Do you have a protocol for purification of total RNA from fatty tissues using QIAzol Lysis Reagent and MaXtract High Density?

Yes, we have the following protocols:

  • Purification of total RNA from fatty tissues using QIAzol Lysis Reagent, MaXtract High Density, and the TissueRuptor (RY29).
  • Purification of total RNA from fatty tissues using QIAzol Lysis Reagent, MaXtract High Density, and the TissueLyser (RY30).
  • Purification of total RNA from fatty tissues using the RNeasy Lipid Tissue Mini Kit and MaXtract High Density (RY31).
FAQ ID -1550
Is it possible to use MaXtract for an organic extraction with a mixture of phenol and BCP (1 bromine chlorpropane)?

Yes, this application is possible with both MaXtract Low and High Density Tubes. A sufficient quantity of BCP should be used when using MaXtract High Density, in order to achieve a stable gel phase. BCP increases the density of the organic phase in the same way as chloroform.


Does the addition of sample and organic solution to the MaXtract Tubes require a specific pipetting sequence?

No. The functional efficiency of the MaXtract Low and High Density Tubes does not depend on the pipetting sequence.


FAQ ID -1307
Can frozen sample material pulverized in liquid nitrogen be directly added to MaXtract tubes?

If organic solvents are added immediately following the filling of MaXtract Low and High Density Tubes with the frozen sample, it should not have any negative effect on the functionality of the tubes.


FAQ ID -1301
Can the MaXtract High Density Tube be used with QIAzol to isolate RNA?
FAQ ID -1304
Which density gel type is contained in the yellow or green MaXtract Tubes?

MaXtract High Density gel is found in the yellow tubes, and MaXtract Low Density gel is contained in the green tubes.


FAQ ID -1315
Can several extraction steps be performed in the same MaXtract tube?

Yes, if a sufficiently large MaXtract tube has been selected for the extraction it is possible to perform multiple purification steps in this tube. Sample and organic solvent are placed in the MaXtract tube, mixed and centrifuged. Organic solvent is then added again to the aqueous phase separated by the gel, followed by mixing and centrifuging. Following the last extraction step, the sample is transferred to a new tube for storage.

For the purification of samples with high protein content, we recommend using a new MaXtract tube for each extraction step.


FAQ ID -1302
When isolating DNA from plant cells using CTAB, should MaXtract Low or High Density be used?

CTAB as a rule increases the density of the aqueous phase. Therefore, MaXtract High Density should be used for the organic extraction of DNA from CTAB samples.

Depending on the amount of CTAB used, the density of the sample can become too high for the MaXtract High Density Tube, leading to a gel barrier above the aqueous phase. In this case, puncture the gel with the tip of a pipette and dilute the aqueous phase with either distilled water or TE buffer. Mix again and then centrifuge. However, we recommend to repeat the separation in a new MaXtract tube.


FAQ ID -1308
Can a phenol-chloroform ratio different from 1:1 also be used with MaXtract Low and High Density?

A phenol-chloroform ratio of 1:1 is advantageous for the phase separation when using MaXtract Low and High Density, since the MaXtract interphase has the greatest stability at this ratio.

Methods using a phenol-chloroform ratio of as much as 6:1 are also possible with MaXtract. However, MaXtract can partly precipitate onto the bottom of the tube in this case.

If the phenol-chloroform ratio is greater than 1:1, it is necessary to use MaXtract Low Density Tubes. Note that this MaXtract type is not compatible with applications in which the aqueous phase has a high density (e.g., isolation of plasmid DNA and RNA).


FAQ ID -1309
If both MaXtract Low Density and High Density is suitable for an application, which type is preferable to use?

In this case, both MaXtract Low and High Density Tubes can be used with the same success. We principally recommend testing both MaXtract types.



FAQ ID -1310
Are MaXtract tubes siliconized?

No, MaXtract Low and High Density tubes are not coated in any way.


FAQ ID -1298