hi im new to research and have been told to always prepare the 5% milk FRESH each time and not to reuse it for other days, ie: store leftovers at -20 deg and used on other days.
but i realise that i was taught to recycle my primary antibody(-20 degrees) after western blot after each use and i normally dilute these antibodies in 5% milk. Is this even a good idea and has anyone tried this?
Dear Iwan,
for me, it was never a problem to use the freshly prepared 5% milk for up to 5 days when I kept it at 4°C (and prepared it in sterile bottles). But after blocking the membrane, I throw the used milk away. I just keep the milk I didn't use for blocking.
Furthermore, I'm reusing my primary antibodies the same way as you described it. If you have an eye (and nose ;-) ) on the milk, it should be fine.
Good luck with your experiments!
Nadja
Dear Iwan
i agree with the last comment.
- I routinely keep my antibodies in 3% milk for 1 week at 4C for at least 1 week.
- In fact they can be kept for longer especially if you add 0.1% sodium azide but beyond 2 weeks you tend to flocculation and sometimes a yellowing of casein milk protein
- Thus try and use within 1 week
- i have never frozen
Hi Iwan
I store the antibodies in 5%BSA at 4C, they can work well at least 1month.
I don't recommend 5% milk for it is esay to go bad.
You can also try to dilute the antibodies in 1%BSA with 0.001%NaN3 ( 5ul in 5ml) at -20C, it can be used more than 10 times ( it depends on your antibodies).
Good luck!
I would say using 5% BSA other than 3% milk is better for storage as per my experience BSA can be better stored for long as compared to milk. Keep at 4oC for a month. but check for any signs of growth and turbidity before use. Again BSA can be better visibly checked for contamination and growth. Best wishes
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