Peptide Concentration & Molarity Reference

Peptide concentration and molarity reference

This page is a laboratory reference for expressing the concentration of a reconstituted research peptide solution. It provides formulas only. It does not provide, and must not be used to derive, any dose or administration amount for humans or animals.

Mass concentration

Concentration (mg/mL) = peptide mass in the vial (mg) ÷ volume of solvent (mL)

Example: 5 mg of lyophilised peptide dissolved in 2.0 mL of solvent gives 2.5 mg/mL (2,500 µg/mL).

Molar concentration

Molarity (mol/L) = concentration (g/L) ÷ molecular weight (g/mol). Note that 1 mg/mL equals 1 g/L.

Example: BPC-157 has a molecular weight of approximately 1,419.5 g/mol. A 2.5 mg/mL solution is 2.5 g/L ÷ 1,419.5 g/mol ≈ 1.76 × 10⁻³ mol/L, i.e. about 1.76 mM.

Preparing working dilutions

For assay working solutions use C₁ × V₁ = C₂ × V₂. Example: to prepare 1.0 mL of a 100 µM working solution from a 1.76 mM stock, take 1.76 mM × V₁ = 100 µM × 1.0 mL, so V₁ ≈ 56.8 µL of stock made up to 1.0 mL with buffer.

Laboratory notes

• Use calibrated pipettes and record lot number, solvent, date and final concentration on every vial label.
• Net peptide content on the certificate of analysis may be below 100% (counter-ions, water); correct the mass if your protocol requires it.
• Store stock solutions according to the product data sheet; aliquot to avoid repeated freeze–thaw cycles.

For laboratory research use only. Not for human or veterinary consumption.
Usage exclusivement réservé à la recherche en laboratoire. Non destiné à la consommation humaine ou vétérinaire.