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🔬 Purity & Potency Calculator

Calculate the corrected weight to weigh based on purity percentage or potency value of your reference standard.

Required Weight (theoretical)

Purity of Standard

From Certificate of Analysis (CoA)

Corrected Weight to Weigh

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💡 Why this matters: Reference standards are never 100% pure. A standard labelled 99.2% purity means for every 100 mg you weigh, only 99.2 mg is the actual compound. Always apply purity correction to avoid systematic errors in your analytical results.

⚠️ Verify before use: Double-check critical weighing calculations independently, especially for regulated or validated methods.

📖 Example (Purity mode): You need 10 mg of a reagent with stated purity 97.5%. Adjusted mass to weigh = 10 ÷ 0.975 = 10.26 mg. Report in thesis: "10 mg (adjusted for purity, actual mass weighed: 10.26 mg)."

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CoA-based

Uses the purity or potency value directly from your Certificate of Analysis.

✅

ICH compliant

Purity correction is a required step in ICH Q2(R1) method validation.

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✔ Formulas last verified against primary references: March 2025 · Report an error

⚠️ Report an incorrect calculation

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Correcting for reagent purity in gravimetric preparation

Analytical grade reagents rarely achieve 100% purity. A 97.5% stated purity means 2.5% of every weighed mass is impurity or solvent of crystallisation. Adjusted mass = desired mass ÷ (purity/100). For enzyme and antibody preparations, activity units rather than mass purity are used — 1 Unit is typically the amount of enzyme that catalyses the conversion of 1 µmol of substrate per minute under defined conditions. Always record lot number and stated activity/purity from the CoA in your lab notebook.