Failure Case Library

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

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

Tissue detachment / sections fall off the slide

Tissue falls off during staining; sections become broken or missing; results cannot be interpreted.

💡 4 causes ✓ 4 fixes
Immunohistochemistry (IHC) critical

False negative — no staining at all

Even the positive control shows no staining; expected positive regions are completely blank; the experiment failed.

💡 4 causes ✓ 4 fixes
Immunohistochemistry (IHC) moderate

Edge effect / uneven staining across the slide

Slide edges show darker staining than center, or one half stains more than the other; reproducibility between fields is poor.

💡 4 causes ✓ 4 fixes
Immunohistochemistry (IHC) severe

Abnormal nuclear staining (wrong subcellular localization)

Cell nuclei show strong staining when they shouldn't, or expected positive nuclei show no staining; nuclear/cytoplasmic localization is wrong.

💡 4 causes ✓ 4 fixes
Immunohistochemistry (IHC) severe

Weak staining / signal too faint

Positive regions show very pale staining; barely distinguishable from negative control; signal appears dotted or discontinuous.

💡 5 causes ✓ 5 fixes
Immunohistochemistry (IHC) severe

Strong positive background / non-specific staining

Whole slide appears brown/diffuse stained; negative control also shows signal; impossible to distinguish true positive signal.

💡 5 causes ✓ 5 fixes