Question.
I have tried to find a general instruction for the shelf life of antibody working solutions.
With automated IHC you usually fill the container with the working solution and depending on the frequency of usage they stay on the instrument at room temperature (or higher) or are put in the fridge again.
The working solutions are up to 10 ml and may last for months. The antibody-diluent is from the same company of the instrument. The titers are in a range from 1:10 to 1:3000 so a very heterogeny situation.
How do you handle this? Have you a general rule? when the solution has to be discarded? Is it just a matter of positive controls?
Answer 1.
This article should be useful.
Tony Henwood MSc, BAppSc, GradDipSysAnalys, CT(ASC), FFSc(RCPA) (Retired), Principal Scientist, the Children’s Hospital at Westmead (Retired), Adjunct Fellow, School of Medicine, University of Western Sydney.
Answer 2.
I will only add to this - run positive and negative tests for every run.
Naira Margaryan
Answer 3.
Thank you for the interesting article. It reflects my personal experience. Nevertheless accreditation rules overrule the experience and in an diagnostic lab we have to discard the reagents.
My question regards more the practical approach with working solutions. What is your experience how long the working solutions are "good enough" for using.
Gudrun Lang
Answer 4.
As presented in the paper, many working dilutions survive without contamination for many years. For example, factor 8 (21 years), factor 13a (19 years) and epithelial membrane antigen (17 years). There were no failed verifications and to date, the average life after expiration was 6 years; eight antibodies exceeded 6 years. All the other antibodies would probably have similar survival times but were exhausted before reaching these times.
Tony Henwood
Answer 5.
I run a research lab with automated staining and truthfully, I make my dilutions fresh for each run because proteins are so different in their stability.
Colleen Forster HT(ASCP)QIHC