Failure Case Library

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

All Techniques (8) 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)
Western Blot (Sigma Protocol) severe

Incorrect Antibody Selection

No signal or unexpected banding pattern despite proper protocol execution

💡 3 causes ✓ 4 fixes
Western Blot (Sigma Protocol) moderate

Enzyme Inhibitor Interference

No signal or very weak signal despite proper antibody binding

💡 2 causes ✓ 2 fixes
Western Blot (Sigma Protocol) moderate

Inactive Chemiluminescent Detection

No signal detected when using chemiluminescent detection method despite proper procedure

💡 3 causes ✓ 3 fixes
Western Blot (Sigma Protocol) minor

Non-parallel Bands

Protein bands appear curved, wavy, or not parallel to each other

💡 1 causes ✓ 2 fixes
Western Blot (Sigma Protocol) severe

Poor Protein Transfer

Proteins do not transfer efficiently from gel to membrane, resulting in weak or no signal

💡 4 causes ✓ 4 fixes
Western Blot (Sigma Protocol) minor

Black Spots on Membrane

Random black spots or speckles appear on the western blot membrane

💡 2 causes ✓ 2 fixes
Western Blot (Sigma Protocol) moderate

High Background or Non-specific Bands

Excessive background staining across the membrane or multiple unwanted bands appear

💡 5 causes ✓ 5 fixes
Western Blot (Sigma Protocol) severe

No Signal or Weak Signal

No bands or very faint bands appear on the western blot after detection

💡 5 causes ✓ 5 fixes