Detailed Procedures for the Removal of Sodium Azide from Antibody Solutions

Sodium azide is a preservative that can effectively inhibit the growth of contaminants and is contained in some antibody products. However, sodium azide is toxic to cells, which, as recommended, should be removed from antibody solutions in process of cell culture assays or coupling.

The following three methods can be used to remove sodium azide.

The Removal of Sodium Azide by Dialysis

The dialysis device can be used to remove sodium azide from samples ranging in volume from 0.1 mL to 70 mL. Due to the relatively low molecular weight of sodium azide (65 Da) compared to IgG (150 kDa) and IgM (~600 kDa), using a membrane with a pore size cutoff of 10–30 kDa will allow sodium azide to pass through the membrane, and antibodies and other proteins in solution will retain.

Materials Required

Dialysis membrane/tubing of appropriate diameter and length to accommodate the sample volume (10–30 kDa molecular weight cutoff)
Dialysis buffer, such as PBS, TBS, or HEPES (pH range 6–8)
Large beaker
Magnetic stirrer at 4°C
Stirring bar

Operating Procedures

Assemble the dialysis device according to the manufacturer's recommendations. Pre-treat the membrane in dialysis buffer for at least 1–2 minutes to hydrate the membrane.
Transfer the antibody solution to the dialysis device.
Place the dialysis device into an appropriately sized beaker with at least 1 L of buffer in which the antibody will be dialyzed. Place the beaker on a magnetic stirrer and dialyze at 4°C for at least 1 hour.
Replace the buffer and dialyze repetitively for at least 1 hour until the desired number of buffer changes is reached. Make sure to change the buffer at least 3 times.

Tips

If possible, all materials should be sterilized and the resulting preparation should be processed aseptically. It is recommended that this be operated at low temperatures, as the antibody is no longer protected by preservatives.

The Removal of Sodium Azide by Desalting

This procedure is suitable for smaller volumes of 1–3 mL. The desalting resin has size exclusion properties and consists of small particles with various pore sizes. Particles of different molecular weights will elute through the size-exclusion matrix at different rates. The Sephadex G25 column system or equivalent is effective in removing sodium azide from antibody samples. Pre-packed Sephadex spin columns are readily available for this procedure.

Materials Required

Sephadex G25 spin columns
Equilibration buffer
Centrifuges

Operating Procedures

If using a commercially available purification column, please refer to the manufacturer's instructions for use.
Remove the cap from the spinning column and centrifuge at 1,000 g for 2 minutes to remove the storage solution.
Place the column in a collection tube.
Fill the column with equilibration buffer according to the manufacturer's recommendations and centrifuge at 1,000 g for 2 minutes.
Repeat 3 times and discard the collected flow-through solution.
Add 1–3 mL of the antibody sample slowly to the middle of the packed bed and centrifuge at 1,000 g for 2 minutes.
Collect and recover the eluate (antibody) in the collection tube.

The Removal of Sodium Azide by Antibody Purification Service

Antibody purification removes impurities effectively, including sodium azide, to ensure the accuracy of the study.

Creative Biolabs provides professional antibody purification services.

View Antibody & Protein Purification Service

Disclaimer

This procedure should only be as a guideline. Please keep in mind that Creative Biolabs cannot guarantee the specific effectiveness of the client's removal of sodium azide.

All listed services and products are For Research Use Only. Do Not use in any diagnostic or therapeutic applications.

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