Performance Characteristics for Identification Tests: What’s Actually Required?

Performance characteristics are method validation parameters that help determine whether a test method is fit for its intended purpose. These include:

·       Specificity/Selectivity

·       Precision

·       Accuracy

·       Detection Limit (LOD)

·       Quantitation Limit (LOQ)

·       Response/Linearity

·       Range

·       Robustness

Performance characteristics should be selected based on the type of test being validated.

Let us find out performance characteristics for qualitative test: Identification tests (like using UV to identify Metformin).

✅ Specificity: Absolutely required. It ensures that the analyte (e.g., Metformin) is correctly identified without interference from excipients or impurities. A mismatch could lead to false negatives. So yes — test for interference, always!

❌ Precision: Not applicable. Since identification tests don’t generate numerical values, you can’t calculate degree of scatter or %RSD.

Still, repeating the test helps confirm procedural consistency.

❌ Accuracy: Also not feasible. You can’t measure ‘amount found’ in a qualitative test — so recovery studies don’t apply here.

❌ Linearity: Linearity requires measurable response vs. concentration. But in identity tests, no such data exists — so this is not relevant.

❌ LOD/LOQ:Not needed. These apply when you want to detect trace levels — not when you're confirming presence.

🟡 Robustness: Optional but recommended — especially if the test involves multiple steps, critical parameters, or will be used across different labs or analysts.

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Best Regards

Bhaskar Napte,

India’s Leading Pharma Coach