Core QC Checks & Validation Metrics

Definitions, test approach, and acceptance criteria for the 7 QC checks used to verify ELISA kit performance before batch release.

Specificity

Cross-reactivity is assessed to confirm the signal is driven by the intended target—not related proteins.

• Definition: Ability to detect the intended analyte without interference from related proteins.
• How we test: Evaluate related-protein panels and confirm no detectable cross-reactivity under defined conditions.
• Acceptance criteria: No detectable cross-reactivity/interference under defined test conditions.

Example kit: Human Cathepsin D ELISA Kit PicoKine® (EK0672)

Representative QC snapshot. Click to open full-size chart.

Sensitivity (MDD)

MDD is determined from 20× zero-standard replicates (Mean + 2SD) and mapped to the standard curve.

• Definition: Minimum Detectable Dose (MDD) estimates the lowest analyte level distinguishable from background.
• How we test: 20× zero standard → compute OD threshold (Mean + 2SD) → map to standard curve to obtain MDD.
• Acceptance criteria: Meets the kit’s validated sensitivity specification for its intended range/sample types.

Example kit: Human IL-6/Interleukin-6 ELISA Kit PicoKine® (EK0410)

Representative QC snapshot. Click to open full-size chart.

Precision (Intra/Inter-assay CV)

CV is calculated from real runs to verify repeatability within an assay and consistency across runs.

• Definition: Intra-assay and inter-assay consistency reflect the coefficient of variation (CV%) of the same batch of ELISA Kit within a single plate and across different plates.
• How we test: ELISA intra-assay consistency is measured using wells from the same plate/assay kit. ELISA inter-assay consistency is measured using wells from different plates from the same batch production/lot.
• Acceptance criteria: Intra-assay CV < 10%; inter-assay CV verified per internal release criteria.

Example kit: Mouse TNF Alpha/Tumor necrosis factor ELISA Kit PicoKine® (EK0527)

Representative QC snapshot. Click to open full-size chart.

Dilution Linearity

Verifies quantitation stays reliable across a dilution series (Observed vs Expected).

• Definition: Dilutions should derive the same final analyte concentration for a sample.
• How we test: Run a dilution series using kit diluents across the assay range; express results as % observed from expected.
• Acceptance criteria: 80–120% (Observed/Expected).

Example kit: Human EGF ELISA Kit PicoKine® (EK0539)

Representative QC snapshot. Click to open full-size chart.

Recovery (Spike Recovery)

Evaluates assay accuracy in relevant sample matrices (e.g., serum/plasma).

• Definition: Add known analyte levels into matrices and evaluate % recovered.
• How we test: Spike low/medium/high levels into validated matrices and calculate recovery.
• Acceptance criteria: 80–120%.

Example kit: Human TFF1/PS2 ELISA Kit PicoKine® (EK1232)

Representative QC snapshot. Click to open full-size chart.

Reproducibility (Lot-to-lot)

Monitors between-lot variation to support consistent results across kit lots.

• Definition: Between-lot reproducibility evaluates variation across different kit lots.
• How we test: Assay multiple lots using samples at different target concentrations and calculate between-lot CV%.
• Acceptance criteria: Lot-to-lot CV < 15%.

Example kit: Human MPO/Myeloperoxidase ELISA Kit PicoKine® (EK0850)

Representative QC snapshot. Click to open full-size chart.

Stability

Tracks kit performance over time to ensure results remain within the defined deviation window.

• Definition: Stability confirms performance remains acceptable during storage/handling over time.
• How we test: Re-test defined samples at multiple time points using the same lot and evaluate deviation versus baseline.
• Acceptance criteria: Performance remains within the defined deviation window.

Example kit: Human EGF ELISA Kit PicoKine® (EK0325)

Representative QC snapshot. Click to open full-size chart.