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Calculate the actual peptide content from a label amount, accounting for HPLC purity, salt form counter-ions, and water content.
The amount stated on the vial label
From the Certificate of Analysis (HPLC purity)
Typical acetate salt correction (~13% counter-ion)
From Karl Fischer titration on the COA, if available
from 10.00 mg label claim
The label amount is corrected sequentially for HPLC purity (removes impurities), salt form (removes counter-ion mass), and water content (removes residual moisture) to yield the actual active peptide mass.
| Salt Form | Correction Factor | Counter-Ion Weight | Notes |
|---|---|---|---|
| Free base | 1.00 | 0% | No counter-ion present |
| HCl | 0.92 | ~8% | Common for small peptides; range 0.90-0.95 |
| Acetate | 0.87 | ~13% | Very common; range 0.85-0.90 |
| TFA | 0.75 | ~25% | Largest correction; range 0.70-0.80; common from HPLC purification |
Actual correction factors vary by peptide size and number of basic residues. These are typical average values. For precise work, calculate from the molecular weight of the free-base peptide and its salt form.
Educational purposes only
This calculator is provided for educational and informational purposes only. It does not constitute medical advice. Salt form correction factors are approximate averages and vary by peptide. Always consult a qualified professional and verify calculations independently.