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)
ELISPOT severe

Merged or Indistinguishable Spots

Spots merge together and become indistinguishable, making it impossible to count individual cytokine-secreting cells. This results in large, confluent areas instead of discrete spots.

💡 4 causes ✓ 4 fixes
ELISPOT severe

False Positive Spots and High Background

Non-specific spots appear in negative control wells or throughout the plate. Background signal is elevated, making spot discrimination difficult.

💡 6 causes ✓ 6 fixes
ELISPOT critical

No Spots or Very Weak Signal

Few or no spots are visible after development, or spots are extremely faint and difficult to detect even though cytokine-secreting cells should be present.

💡 5 causes ✓ 5 fixes
ELISPOT severe

Poorly Defined or Fuzzy Spots

Spots lack sharp borders and appear fuzzy or poorly defined, making automated or manual counting difficult. The reader has trouble distinguishing individual spots.

💡 5 causes ✓ 5 fixes
ELISPOT moderate

Over-Developed Plate with Excessive Background Color

The entire membrane has excessive background color development, reducing contrast between spots and background. Spots may be obscured by high background signal.

💡 4 causes ✓ 4 fixes
ELISPOT moderate

Inconsistent Results Between Wells (Edge Effects)

Results vary significantly between wells that should be replicates. Edge wells often show different spot counts or characteristics compared to central wells, creating systematic position-dependent effects.

💡 4 causes ✓ 4 fixes
ELISPOT severe

Physical Membrane Damage and Artifacts

Membrane shows physical damage, scratches, or irregular patterns. Spots may appear distorted or artifacts present as non-specific signals.

💡 4 causes ✓ 4 fixes
ELISPOT moderate

White Spots in Center of Normal Spots (Donut Pattern)

Spots develop with white or lighter centers surrounded by darker rings, creating a donut-like appearance. This is more common with enzymatic detection methods.

💡 3 causes ✓ 3 fixes