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Hi,

I'm using the ATP kit and I have a little problem with it.
The kit works well when the final reagent is stored at +4°C but not when is aliquoted and stored at -20°C.
I used 2 kits (same batch) and obtained the same results: the fluorescence decreased rapidly in the week with the frozen aliquots.

Do you have an explanation?

Thanks

Hello,

it is very unusual that an aliquoted amount of the final reaction mix of the sensitive ATP assay losses activity when stored at -20 degrees and thawed once for use. Apparently, no mistake was made during your preparation of the final assay mix.
I advice you to not perform several freeze/thaw cycles with the assay mix, I tested up to 12 complete freeze/thaw cycles with a total loss of activity of < 20% compared to a fresh batch.
The loss of sensitivity/assay activity can also occur due to damage of luciferin by light. Even pipetting the assay in bright sunlight can have a negative influence of the assay sensitivity.
Also, Remind that using the sensitive assay it is strongly recommended to read out the samples after exactly 10-15 minutes. Longer incubation times with the reaction mix will result in weaker signals.

best regards