Real lab failures, root causes, and fixes — curated and bilingually annotated by our team.
No detectable signal or extremely weak signal in ELISA even when target protein is expected to be present. Signal may be inconsistent across wells.
Low or no signal despite proper assay setup. High concentration samples may show weak signal while low concentration samples are undetectable.
No signal or very low signal readings from plate reader despite visible color development or expected fluorescence. Signal does not correlate with visual observations.
No signal or minimal signal in indirect ELISA despite proper coating and blocking. Positive controls with matched antibodies work correctly.
No or very weak signal despite correct antibody binding. Signal loss occurs after addition of detection reagent. Other wells using different buffers show normal signal.
Unpredictable or absent signal despite following protocol. Results are inconsistent and do not match expected standard curves. Signal may vary dramatically between experiments.
Progressive signal loss over time using the same reagents. Previously working protocols suddenly fail. Positive controls that worked before now show reduced or no signal.
Consistently weak signal across all samples including positive controls. Signal improves when experiment is repeated with attention to temperature. Longer incubations partially compensate.
Signal progressively decreases with increased wash steps or aggressive washing. Reducing wash stringency restores signal. Edge wells show lower signal than center wells.
Signal is present but consistently lower than expected. Positive controls show weak but detectable signal while samples are near background.
Sporadic signal loss or high background that worsens over time during multi-day experiments. Cloudy or turbid buffer appearance. Inconsistent results when using same buffer batch.
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