The OECD 442E standard recommends the use of the EURL ECVAM DB-ALM n ​​158 protocol in tests.

What deviations from the protocol ARE ALLOWED?

In case of test substances, do I have to correctly perform the designation for all 10 compounds, or is 8 enough (because, for example, a positive control did not come out)?

Determining CV75 for test substances with a negative result , should I increase the dilution of stock solutions if the lactic acid dose giving 75% viability (CV75) has reached 1471,79 g / ml and the reference range of the standard is: 1500-5000ug / ml. (in the 2500 and 5000 tests they gave about 5% viability) (CV was determined from doses of 1250 and 2500).

How long can the interval be between the determination of CV75 and the study of CD54 and CD86 markers?

When determining CV75 in 2 duplicate for compound 1 on the same day, can I use the same starting solution for the preparation of working solutions?

I try to work according to the above protocol.