Hi,
I’m a chemist who recently started a biochemistry PhD. I’m developing methods primarily Biosensor analysis, and some NMR, mass spec, HPLC analysis. I've never worked with antibodies before so I’m looking for some help:

1. I received 1000ul of antibody which I aliquoted out into smaller 10ul amount, but I think my antibody is degrading after 3-5days because I’m not getting the same RU response after this period of time. Could my antibody be degrading this quickly? I read that adding sodium azide with preserve it, how do I go about adding this?

Thank you

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Depends of the antibody but usually they are pretty robust, did you filter them sterile before to do the aliquots Do you see any clumps into your solution ?

Yes Na Azide is killing the possible contaminations and therfore enhance stability but Azide is also known to alter with some process like inhibition of Alkaline Phosphatase detection and it's also very poisonous

jipes

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Hi jipes,

No I didn’t filter it. It didn’t appear to have any clumps in it. Could you recommend any other preservatives to use?

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Filtration through 0.22micrometers filter is usually the best way to go

Do you dilute a lot your antibody prior to use ? Do you keep the diluted antibody between tests ?

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Yep, when I first aliquoted it out I diluted it 1:200, with this dilution I got a relative response of 395 RU....1 week later (using the same aliquot) I got a relative response of 45 RU!!!
Ive been storing it concentrated and only diluting just prior to using...

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Yes that's the right way to do it, but you didn't say if your second measurement was done with the same aliquot dilutied or with a fresh dilution ?

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sorry it was a completely different aliquot (but it was mesured out at the same time, stored under the same conditions,so identical really), but I diluted it in the same way, 1:200.... Im sorry for all the questions but like I said lve never worked with antibody before so Im stumped!!

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what are your storage conditions?

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I store it concentrated, at -20, I have approx 150-200ul left but I don’t want to defrost it until I find out if I can add preservative

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is this an antiserum or a purified antibody?

when you defrost it, do you see anything floating or out of solution?

azide will prevent microbial growth but will have no other effect on preserving the antibody.it is required if you are storing without freezing.

it would be strange to see microbial growth in frozen aliquots but you could denature the antibody by freeze-thaw.

is your freezer auto-defrost? the defrost cycle may have an effect on the stability of your antibody.

(just a few things to consider)

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