Failure Case Library

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

All Techniques (9) 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)
Flow Cytometry (Fixation & Permeabilization) severe

Altered Fluorescence Intensity After Fixation

Fluorescence signal intensity changes dramatically after fixation, particularly affecting tandem dyes. Populations may shift or show unexpected brightness changes compared to unfixed controls.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation & Permeabilization) severe

Epitope Degradation from Harsh Permeabilization

Loss of antibody binding or weak signal for intracellular targets despite successful cell permeabilization. Positive controls show reduced or absent staining.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation & Permeabilization) severe

Incorrect Permeabilization Method for Target Location

Weak or absent staining of nuclear transcription factors when using detergent-based permeabilization, or poor cytoplasmic protein detection with alcohol-based methods.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation & Permeabilization) critical

Reversed Fixation and Permeabilization Order

Poor cell morphology, increased autofluorescence, or loss of intracellular antigens when permeabilization is performed before fixation.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation & Permeabilization) moderate

Photobleaching During Fixation and Storage

Progressive loss of fluorescence signal over time, particularly noticeable in samples fixed and stored for later analysis. Light-sensitive fluorophores show dramatically reduced intensity.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation & Permeabilization) critical

Inadequate Pathogen Inactivation in Infectious Samples

Biosafety concerns when handling infectious disease samples due to incomplete pathogen inactivation. Risk of exposure when samples are removed from high-containment facilities.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation & Permeabilization) moderate

Missing Fixation and Permeabilization Controls

Difficulty interpreting results due to unknown effects of fixation and permeabilization on fluorescence intensity and population distribution. Unable to distinguish artifacts from true biological changes.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation & Permeabilization) severe

Lack of Antibody-Specific Protocol Validation

Inconsistent or failed staining when applying generic fixation/permeabilization protocols to different antibodies, especially transcription factors. Expected positive populations are negative or dim.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation & Permeabilization) moderate

Sample Quality Loss During Overnight Storage

Reduced staining intensity or increased background when fixed samples are analyzed the next day. Signal-to-noise ratio deteriorates despite proper fixation.

💡 4 causes ✓ 4 fixes