Rapid Equilibrium Dialysis (RED) Device Inserts, 8K MWCO, 50 Inserts - FAQs

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31 product FAQs found

Why can I only process 48 samples on a 96-well plate using the RED device?

Each sample requires two chambers for equilibrium dialysis to take place (96/2 = 48).

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

Can I heat the PTFE block on a hot plate to maintain the temperature of the RED Device?

Yes, as most assays are performed at physiological temperature (37.5 degrees C).

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

If I see vapor condensing on the clear sealing film, will the loss of water vapor affect the result when using the RED Device?

No. It will not affect the equilibrium.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

How do I mix the samples to speed reaching equilibrium when using the RED Device?

Once samples are loaded into the PTFE plate it should be placed on a shaking device. With an orbital shaker 100 rpm works well. For an up and down shaker, 20 rpm is sufficient.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

With the rapid equilibrium dialysis (RED) system, if my compound has low solubility in aqueous buffer, can I use DMSO and if so, at what concentration?

A final concentration of 1% DMSO is acceptable and will not affect the study. While DMF has not been tested, it is expected that DMF should be similar to DMSO in terms of use.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

If we use radioactive compounds in our study, will the PTFE plate be contaminated, preventing reuse of the RED Device?

No. After use, rinse the PTFE plate in 20% ethanol in water and rinse with ultrapure water at least two times. No radioactivity will remain after these rinses.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

Can the RED Devices be reused?

No, these are designed for a single use, as plasma is sticky and cannot be removed from the unit. The PTFE plate is designed for multiple uses.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

What is the minimum volume of plasma that I can use with the RED Device?

The lowest validated volume for the RED Device sample chamber is 50 µl of plasma.

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What samples are typically tested for binding of ligands with the RED Device?

Plasma samples from human, mouse and rat. For toxicology studies, monkey is also typically tested. Typically pooled plasma samples purchased from commercial vendors are used, although researchers could test the differences in plasma from various physiological states using the RED Devices.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

Is there any non-specific binding of compounds to the RED device?

The container for the device is PTFE and the insert is made of high density polyethylene (HDPE) and are highly hydrophobic. The regenerated cellulose membrane is a standard material for commercial dialysis devices. A recovery study shows a consistency of 85% recovery of high and low protein binding compounds. This result is indicative of minimal non-specific binding.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

Is there a volume shift in either RED Device sample?

Volume shift in the plasma is unusual due to how quickly equilibrium can be reached with the RED Device. If much longer incubation times are used, there can be an increase in the volume of the plasma. However, the ligand will still reach equilibrium, having free ligand at the same concentration on both sides of the membrane.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

Why is the volume different between the membrane chamber and the buffer chamber of the RED Device? Will it affect the results?

The difference in liquid volume is to maintain the same level (height) between the two chambers. The equilibrium constant depends only on the concentration of the ligand, not the volume.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

How long does it take the RED Device to reach equilibrium dialysis?

In most cases 4 hours is sufficient to reach equilibrium. This is due to the high surface area to volume ratio for the membrane (7.4:1).

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

Are the RED Device units sterile or endotoxin free?

The units do not undergo a sterilization procedure nor are they tested for endotoxin content.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

Is there any preprocessing, such as rinsing the RED Device Inserts, which is required before they can be used?

No. The inserts can be used directly out of the package, no presoaking or rinsing of the membrane is needed.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

What is the pore size or molecular weight cut-off (MWCO) for the membrane of the RED Device Inserts?

The nominal MWCO is 6,000-8,000 Daltons as specified by the manufacturer.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

What is the membrane material in the RED Device Inserts?

Regenerated cellulose with a low glycerol content as a humectant.

Find additional tips, troubleshooting help, and resources within our Protein Purification and Isolation Support Center.

Why can I only process 48 samples on a 96-well plate with the rapid equilibrium dialysis (RED) system?

Each sample requires two chambers for equilibrium dialysis to take place (96/2 = 48); one chamber for the plasma sample, the other for buffer.

Can the rapid equilibrium dialysis (RED) device be used with cells or virus included in the "plasma" side?

We have not tested the units with cells or viral particles. Customers would have to design and optimize their experiments to use the RED device with this type of sample.

What samples are typically tested for binding of ligands with the rapid equilibrium dialysis (RED) device?

Plasma samples from human, mouse, and rat are typically tested for binding of ligands with the rapid equilibrium dialysis (RED) device. For toxicology studies, a monkey sample is also tested. Typically, pooled plasma samples purchased from commercial vendors are used, although researchers could test the differences in plasma from various physiological states using the RED devices.

In the rapid equilibrium dialysis (RED) system, do you observe nonspecific binding of compounds to the device?

The container for the device is Teflon (PTFE), the insert is made of high-density polyethylene (HDPE), and they are highly hydrophobic. The regenerated cellulose membrane is a standard material for commercial dialysis devices. A recovery study consistently shows 85% recovery of high and low protein binding compounds. This result is indicative of minimal nonspecific binding, since the recovery between the membrane side and the PTFE/HDPE housing side showed very small difference.

How long does it take to reach equilibrium dialysis in the rapid equilibrium dialysis (RED) system?

In most cases, 4 hours is sufficient to reach equilibrium. This is due to the high surface area-to-volume ratio for the membrane (7.4:1), but can vary with different compounds.

Are the rapid equilibrium dialysis (RED) devices GMP-certified?

No. They are manufactured in an ISO environment. The Teflon plate is also ISO-certified.

Are the rapid equilibrium dialysis (RED) Device units sterile or endotoxin-free?

No. The units do not undergo a sterilization procedure nor are they tested for endotoxin content.

Is the rapid equilibrium dialysis (RED) system compatible with automation?

Yes. The Teflon Base Plate has the standard 96-well footprint. It can be used with any system compatible with standardized 96-well ELISA plates with 9 by 9 mm well spacing. The single-use format for the RED Device is especially convenient for labs using radioactive materials because the plate can easily be disposed of to minimize contamination and the need for cleaning.

What is the pore size or molecular weight cut-off (MWCO) for the membrane in the rapid equilibrium dialysis (RED) system?

We offer 8K and 12K MWCOs.

What is the membrane material in the rapid equilibrium dialysis (RED) system?

The membrane used is regenerated cellulose with a low glycerol content (acts as a humectant).

Which rapid equilibrium dialysis (RED) system should I use?

Please use our selection table (https://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-mass-spectrometry-analysis/plasma-protein-binding-equilibrium-dialysis.html) to choose the right plasma or tissue-to-plasma protein binding product for your experiment.

What is equilibrium dialysis?

Equilibrium dialysis uses size-defined membranes to separate the free molecules (i.e., those molecules not bound to plasma proteins at equilibrium state). This type of dialysis mimics an in vivo environment. We offer our RED (rapid equilibrium dialysis) and competition RED systems to conduct plasma or tissue-to-plasma protein-binding studies.

What is the difference between your dialysis devices (plates, device, cassettes, flasks)?

Please view our selection table to choose the right dialysis device for your experiment - https://www.thermofisher.com/us/en/home/life-science/protein-biology/protein-purification-isolation/protein-dialysis-desalting-concentration/dialysis-products.html.

What is protein dialysis?

Dialysis is the separation of small and large molecules in a solution by selective diffusion through a semi-permeable membrane. It is generally used for larger sample volumes, and can take hours to overnight for complete dialysis.