Failure Case Library

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

All Techniques (7) 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 Buffers) severe

Low or Diminished Fluorescence Signal After Fixation

Flow cytometry data shows weak or absent fluorescence signals from labeled antibodies following fixation step. Expected positive populations appear dim or shift toward negative, compromising detection sensitivity.

💡 5 causes ✓ 5 fixes
Flow Cytometry (Fixation Buffers) moderate

Elevated Background Fluorescence Post-Fixation

Flow cytometry analysis reveals increased non-specific fluorescence across all populations following fixation. Negative control cells show elevated signal, reducing signal-to-noise ratio and obscuring true positive events.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation Buffers) severe

Fluorophore Degradation from Harsh Fixation Conditions

Specific fluorophores show dramatic signal loss or complete disappearance after fixation while others remain intact. Tandem dyes or photosensitive fluorophores particularly affected, resulting in spectral overlap changes and compensation errors.

💡 4 causes ✓ 5 fixes
Flow Cytometry (Fixation Buffers) moderate

Cell Morphology Distortion and Loss of Scatter Properties

Forward scatter (FSC) and side scatter (SSC) profiles show abnormal patterns after fixation. Cell populations cluster abnormally, size measurements are inconsistent, and gating strategies based on morphology fail to resolve expected populations.

💡 4 causes ✓ 4 fixes
Flow Cytometry (Fixation Buffers) severe

Failed Intracellular Antigen Detection After Fixation

Intracellular markers such as cytokines, transcription factors, or phosphoproteins show no signal despite proper antibody validation. Surface markers stain normally, but internal targets remain undetected indicating permeabilization issues.

💡 4 causes ✓ 5 fixes
Flow Cytometry (Fixation Buffers) moderate

Sample Degradation During Delayed Analysis Storage

Samples fixed for next-day or multi-day analysis show progressive signal loss, increased debris, and population shifts compared to immediate analysis. Data quality deteriorates with storage time despite initial proper fixation.

💡 5 causes ✓ 6 fixes
Flow Cytometry (Fixation Buffers) critical

Inadequate Pathogen Inactivation in Infectious Samples

Samples from infected or potentially hazardous sources show signs of incomplete inactivation, creating biosafety concerns during handling and flow cytometry analysis. Validation assays indicate residual infectious potential.

💡 4 causes ✓ 6 fixes