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Cell Counting Kit-8 (CCK-8) Assay Principle

🚨 Failure Case Library (5) + Submit your own case

severe
OD values are too low — close to background
Most OD values are below 0.1, the curve is essentially flat along the x-axis, and group differences are invisible.
💡 5 · ✓ 5
severe
OD values are too high — beyond detection range
OD450 readings approach or exceed 3.0, the curve hits its upper limit, and treatment vs control look indistinguishable.
💡 5 · ✓ 5
severe
High background — control OD is abnormally elevated
Even blank wells (medium + CCK-8, no cells) show high OD; control group reads abnormally high.
💡 5 · ✓ 5
moderate
High well-to-well variability — poor reproducibility
Parallel wells in the same group give widely different OD values; SD bars are very large.
💡 5 · ✓ 5
moderate
Group differences are too small to distinguish
Treatment and control curves are nearly overlapping, error bars overlap, no statistical significance.
💡 5 · ✓ 5
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