2
mL
2,000
μL
20
μmol
2
mL
2,000
μL
20
μmol
Reconstitution is the process of dissolving a lyophilized (freeze-dried) or powdered compound in a suitable solvent to create a stock solution at a specific concentration. This is a routine procedure in pharmaceutical research, biochemistry, and drug discovery, where compounds are often supplied as dry powders for stability and shipped with a certificate of analysis specifying the molecular weight and purity.
The reconstitution calculation determines how much solvent to add to a known mass of compound to achieve a desired molar concentration: V = mass / (Mw × C). This calculator takes the mass in milligrams, the molecular weight in g/mol, and the desired concentration in millimolar (mM), then computes the required solvent volume in both milliliters and microliters.
Proper reconstitution is critical for accurate experimental results. The compound must be completely dissolved, the solvent must be compatible (DMSO for hydrophobic compounds, water or buffer for hydrophilic ones), and the stock concentration must be high enough to allow further dilution to working concentrations without introducing excessive solvent. Typical stock concentrations range from 1 mM to 100 mM depending on the compound's solubility and the assay requirements.
The reconstitution volume is calculated from the fundamental relationship between mass, moles, and concentration:
V = n / C = (mass / Mw) / C
Expanding with unit conversions:
The calculator also shows the amount of compound in micromoles (μmol), which is useful for planning how many experiments a vial will support.
Practical reconstitution guidelines:
The volume output tells you exactly how much solvent to add to the vial containing the weighed compound. If the calculated volume is very small (under 10 μL), consider using a lower target concentration to work with more manageable volumes. If the volume is very large, the compound may have limited solubility at that concentration — check solubility data before proceeding.
The μmol output helps estimate how many experiments the stock will support. If you need 10 nmol per experiment and have 20 μmol total, you have enough for 2000 experiments (before accounting for pipetting losses).
Inputs
Results
To prepare a 10 mM stock from 5 mg of a compound (MW = 450 g/mol), add 1111 μL (1.11 mL) of DMSO. This yields 11.1 μmol of compound, sufficient for hundreds of experiments at nanomolar working concentrations.
Inputs
Results
Dissolving 1 mg of a peptide (MW = 1500 g/mol) in 667 μL of sterile water gives a 1 mM stock solution with 0.667 μmol of peptide. Peptides are often prepared at lower stock concentrations due to limited solubility.
It depends on the compound. DMSO is the universal first choice for small organic molecules and most drug compounds. Water or PBS is used for salts, sugars, and hydrophilic biomolecules. Ethanol or methanol may be needed for some natural products. Check the supplier's datasheet for solubility information. If no data is available, test dissolution in a small aliquot of solvent first.
The general rule is to make the stock 100-1000× more concentrated than your working concentration. Common targets are 10 mM or 50 mM in DMSO for small molecules. This ensures the final DMSO concentration in assays stays below 0.1-0.5%. For proteins and antibodies, typical stocks are 1-10 mg/mL in appropriate buffer.
Generally no. Most compounds have limited solubility in aqueous media, and the stock would be too dilute. Prepare a concentrated stock in DMSO first, then dilute into media to achieve the working concentration. Exception: highly water-soluble compounds (salts, sugars, some amino acids) can be dissolved directly in media or buffer.
If the compound is 95% pure, the effective mass is mass × 0.95. For a 5 mg vial at 95% purity: effective mass = 4.75 mg. Enter this adjusted mass in the calculator, or prepare at the calculated volume and note that the actual concentration is 95% of the nominal value.
This varies by compound, but as a general rule, minimize freeze-thaw cycles. DMSO stocks are relatively stable for 3-5 cycles, but sensitive compounds (peptides, antibodies, some drugs) may degrade after even 1-2 cycles. Best practice: prepare single-use aliquots at the time of reconstitution.
Try vortexing for 30-60 seconds, then brief sonication (5-10 min in a bath sonicator). Warming to 37°C may help (if the compound is thermally stable). If it still does not dissolve, the concentration exceeds the solubility limit — add more solvent to reduce the target concentration, or try a different solvent. Never use a turbid or particulate stock for quantitative experiments.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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