Hello Alina Makeeva

There are many ways to deal with such a situation.

1. If the primary antibody solution contains sodium azide as a preservative, adjust the final concentration of sodium azide to no more than 0.001%, as higher concentrations may inhibit HRP activity.

2. Even sufficient washing will help to remove the presence of sodium azide.

3. You may also remove sodium azide in an antibody formulation in the following ways:

a. By dialysis or centrifugal filtration: Please refer to the manufacturer’s recommendations for most efficient use of centrifugal filter devices or dialysis equipment (MW of sodium azide ~ 65 D, IgG ~ 150 kDa, IgM ~ 900 kDa).

b. By gel filtration (which is much faster than dialysis). Also, please refer to the manufacturer’s recommendations for most efficient use of suited filter cartridges.

4. Another way would be to use an antibody clean-up kit which is designed for the rapid clean-up of antibody solutions to ensure the antibody is in an optimal buffer and free from interfering agents. This kit uses resin that binds the high abundant, non-IgG proteins and allows the IgG molecules to pass through in a physiological buffer.

5. You may also look out for those vendors which do not use sodium azide as a preservative. One such vendor whom I have heard about is Eurogentec. Their antibodies are delivered in PBS with 0.1% BSA as stabilizer and 0.01% Thimerosal as a preservative. I have not used their antibodies, but you may enquire about their products using the link below.

https://www.eurogentec.com/en/antibodies-reagents

https://www.eurogentec.com/en/faqs/cat17_antibodies#:~:text=Please%20be%20advised%20that%20sera,%C2%B0C%20after%20first%20thawing.

Hope these suggestions are helpful!

Best.