Failure Case Library

Real lab failures, root causes, and fixes — curated and bilingually annotated by our team.

All Techniques (5) Nucleic Acid Quantification (9) Lipid Transfection (8) End-point PCR Primers (9) Cell Culture (Contamination) (7) PCR (Sigma Guide) (12) Flow Cytometry (Controls) (8) PCR / qPCR Plastics (9) PCR (Invitrogen Guide) (8) Cell Culture (Precipitates) (6) Cell Culture (Cell Death) (8) ELISA (Sigma Guide) (6) PCR / RT-PCR Amplification Problems (5) Flow Cytometry (Paraformaldehyde Fixation) (14) Flow Cytometry (Sample Considerations) (14) ELISA (R&D Guide) (10) Western Blot Immunodetection (19) Flow Cytometry (CST Guide) (8) Immunohistochemistry (CST Guide) (14) Immunoprecipitation (CST Guide) (14) ChIP (CST Guide) (8) ELISA Development (9) Western Blot (Sigma Protocol) (8) IP-Western Blot (6) Western Blot (CST Guide) (8) Flow Cytometry (Fixation Buffers) (7) Flow Cytometry (Isotype Controls) (7) Flow Cytometry (Fixation & Permeabilization) (9) Flow Cytometry (Fc Blocking) (7) Flow Cytometry (Compensation) (7) Flow Cytometry (Autofluorescence) (7) Flow Cytometry (Troubleshooting) (8) Tissue Imaging (Autofluorescence) (9) ELISPOT (8) Immunoprecipitation (Protein Obstruction) (1) Immunoprecipitation (No Protein Detected) (5) Immunoprecipitation (High Background) (8) Immunoprecipitation (High Antibody Elution) (1) Immunohistochemistry (No Staining) (9) Immunohistochemistry (High Background) (9) ChIP (PCR Amplification Problems) (4) ChIP (Low Signal) (8) ChIP (Low Resolution with High Background) (6) ChIP (High Background) (1) Western Blot (Blue Background) (1) Western Blot (Unusual Gel Band Appearance) (3) Western Blot (Unexpected Multiple Bands) (7) Western Blot (Misshapen / Uneven Bands) (5) Western Blot (Bands at Wrong MW) (5) Western Blot (Detection Problems) (7) Western Blot (Weak / No Signal) (6) ELISA (Standard Curve Fit Problems) (6) ELISA (Inconsistent Results / High CV) (6) ELISA (High Background) (8) ELISA (Signal Problems) (11) ELISA (Competitive) (18) Cell-free DNA Extraction (8) Bacterial rRNA Depletion (4) RNA Depletion for RNA-seq (7) LAMP (Loop-mediated Isothermal Amplification) (7) HMW DNA Extraction (Monarch) (7) NGS Library Preparation (NEBNext Ultra II) (7) RNA Cleanup (4) DNA Cleanup & Plasmid Purification (7) PCR (Polymerase Chain Reaction) (26) Restriction Enzyme Digest (13) Western Blot (9) Immunohistochemistry (IHC) (6) Colony Formation Assay (10) Transwell Migration / Invasion Assay (5) qPCR (RT-qPCR) (5) Transfection (8) Plasmid Construction (1) Sanger Sequencing (2) Plasmid Mini-prep (1) Plasmid Construction (Double Digest) (1) Protein Extraction (4) Transfection (Co-transfection) (1) Transfection (siRNA Knockdown) (1) CCK-8 Cell Viability Assay (5) Wound Healing Assay (5)
CCK-8 Cell Viability Assay 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 causes ✓ 5 fixes
CCK-8 Cell Viability Assay 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 causes ✓ 5 fixes
CCK-8 Cell Viability Assay moderate

Group differences are too small to distinguish

Treatment and control curves are nearly overlapping, error bars overlap, no statistical significance.

💡 5 causes ✓ 5 fixes
CCK-8 Cell Viability Assay 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 causes ✓ 5 fixes
CCK-8 Cell Viability Assay 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 causes ✓ 5 fixes