Resuspension Calculator

Calculate volumes for reconstituting lyophilized samples

Weight of protein, DNA, or compound to resuspend

Enter to calculate molarity (e.g., 66 kDa protein = 66000 g/mol)

Understanding Resuspension Calculations

Resuspension (reconstitution) is the process of dissolving lyophilized (freeze-dried) materials to a specific concentration. Accurate calculation of the required volume is essential for preparing stock solutions of proteins, antibodies, enzymes, DNA, and small molecules.

Basic Resuspension Formula

Volume (mL) = Mass (mg) / Desired Concentration (mg/mL)

For molarity: Volume (mL) = (Mass (mg) / MW (g/mol)) / Desired Molarity (mM)

Mass-Based Concentration (mg/mL)

Used for proteins, antibodies, and most biomolecules

Molar Concentration (mM or µM)

Used for small molecules and when stoichiometry matters

Unit Concentration (U/mL)

Used for enzymes based on activity rather than mass

Reconstitution Best Practices

Solvent Selection

  • • Water: Sterile, deionized water for general use
  • • PBS: Physiological pH (7.4) for proteins
  • • Buffer: Match protein's optimal pH
  • • DMSO: For hydrophobic small molecules
  • • Ethanol: Alternative organic solvent for compounds

Reconstitution Protocol

  1. Spin vial briefly to collect material at bottom
  2. Add calculated volume of solvent slowly down the side
  3. Let stand 2-5 minutes to hydrate
  4. Gently swirl or pipette (avoid vigorous vortexing)
  5. Ensure complete dissolution before use
  6. Aliquot if needed to avoid freeze-thaw cycles

Stock Solution Tips

  • • Make concentrated stocks (10-100×) for convenience
  • • Label with name, concentration, date, and initials
  • • Store at appropriate temperature (-20°C or -80°C for proteins)
  • • Add glycerol (10-50%) for protein stability
  • • Record lot numbers for reproducibility
  • • Consider making aliquots to minimize contamination

Common Calculations

Example Scenarios

  • Antibody (1 mg vial → 1 mg/mL):
    Add 1.0 mL PBS or sterile water
  • Protein (5 mg → 10 mg/mL):
    Add 0.5 mL buffer (5 mg ÷ 10 mg/mL)
  • Small molecule (10 mg, MW 300 → 100 mM):
    Add 0.333 mL DMSO [(10/300) ÷ 0.1]

Applications

  • 🧪
    Protein Reconstitution: Preparing enzymes, antibodies, and recombinant proteins
  • 💉
    Antibody Preparation: Reconstituting antibodies for Western blots and assays
  • 🔬
    Enzyme Stock Solutions: Making working stocks of restriction enzymes and polymerases
  • 🧬
    DNA/RNA Resuspension: Dissolving lyophilized oligonucleotides and primers
  • 💊
    Drug Compounds: Preparing small molecule stocks for screening assays
  • 🎯
    Standards Preparation: Making calibration standards for analytical methods

🧬Quick Reference

Basic Formula:

V = mass / concentration

Common Units:

mg/mL, mM, µM, U/mL

Typical Stocks:

1-10 mg/mL proteins

Storage:

-20°C or -80°C

Level:

College Biochemistry

🔗Related Calculators

📐Related Formulas

🎯Where It's Used

  • 🔬

    Research Labs

    Daily stock preparation

  • 🧬

    Molecular Biology

    Enzyme and oligo prep

  • 💊

    Pharma Industry

    Compound screening

  • 🏥

    Clinical Labs

    Reagent preparation