Resuspension Calculator
Our biochemistry calculator computes resuspension accurately. Enter measurements for results with formulas and error analysis.
Formula
Volume (mL) = (mass (g) x purity / MW) / (concentration in mol/L) x 1000
Where mass is the weight of the dry compound, MW is the molecular weight in g/mol, purity is expressed as a decimal fraction, and concentration is the desired molar concentration. For mg/mL concentrations, Volume = effective mass / target concentration.
Worked Examples
Example 1: Resuspending a Peptide for Cell Assay
Problem: You have 2 mg of a peptide (MW = 1200 g/mol, purity 95%) and need a 5 mM stock solution. How much DMSO do you need?
Solution: Effective mass = 2 mg x 0.95 = 1.9 mg = 0.0019 g\nMoles = 0.0019 / 1200 = 0.000001583 mol = 0.001583 mmol\nVolume = 0.001583 mmol / 5 mM = 0.000317 L = 0.317 mL = 317 uL
Result: Add 317 uL of DMSO to produce a 5 mM stock solution.
Example 2: Preparing a Drug Solution at mg/mL Concentration
Problem: You have 5 mg of a compound at 98% purity and need a 10 mg/mL solution. What volume of solvent is required?
Solution: Effective mass = 5 mg x 0.98 = 4.9 mg\nVolume = 4.9 mg / 10 (mg/mL) = 0.49 mL = 490 uL
Result: Add 490 uL of solvent to achieve a 10 mg/mL stock concentration.
Frequently Asked Questions
What is resuspension and why is it important in the lab?
Resuspension is the process of dissolving a dry or lyophilized compound (such as a peptide, drug, or reagent) in a suitable solvent to create a solution of a desired concentration. This is one of the most fundamental tasks in biochemistry, molecular biology, and pharmaceutical research. Accurate resuspension ensures that experiments are reproducible and that dosing is precise. Common solvents include DMSO, water, PBS, and ethanol. The choice of solvent depends on the compound solubility profile. Incorrect resuspension volumes can lead to failed experiments, wasted reagents, and unreliable data, making a resuspension calculator an essential laboratory tool.
How do I choose the right solvent for resuspension?
Choosing the right solvent depends on the chemical properties of your compound, including its polarity, pH sensitivity, and intended biological application. Water-soluble compounds can often be resuspended in deionized water, phosphate-buffered saline (PBS), or culture media. Hydrophobic or poorly soluble compounds typically require organic solvents like dimethyl sulfoxide (DMSO), ethanol, or methanol as a first step. When using DMSO, keep the final DMSO concentration below 0.1 percent in cell-based assays to avoid cytotoxicity. Always check the product datasheet for solubility information and recommended solvents before beginning your experiment.
What does molecular weight have to do with resuspension calculations?
Molecular weight (MW) is the bridge between mass and moles, which is critical for preparing molar concentrations. The formula is straightforward: moles equals mass in grams divided by molecular weight in grams per mole. If you need a 10 millimolar solution, you must know the molecular weight to convert from the milligrams of powder you have on hand to the volume of solvent required. For mass-based concentrations like milligrams per milliliter, molecular weight is not needed. Always verify the molecular weight from the certificate of analysis rather than relying on approximate values, as salts and hydration states can alter the effective molecular weight.
How does compound purity affect the resuspension volume?
Compound purity directly impacts how much active material is actually in your vial. If you have 1 milligram of a compound at 95 percent purity, only 0.95 milligrams is the actual active compound; the remaining 0.05 milligrams consists of impurities, salts, or residual solvents. Ignoring purity leads to a systematic error where your actual concentration is lower than intended. Resuspension Calculator adjusts for purity by computing the effective mass before determining the required solvent volume. For high-purity reagents above 98 percent, the correction is minor, but for crude peptides or natural product extracts at 70 to 85 percent purity, the adjustment is essential for accurate experimental results.
Can I use Resuspension Calculator on a mobile device?
Yes. All calculators on NovaCalculator are fully responsive and work on smartphones, tablets, and desktops. The layout adapts automatically to your screen size.
What formula does Resuspension Calculator use?
The formula used is described in the Formula section on this page. It is based on widely accepted standards in the relevant field. If you need a specific reference or citation, the References section provides links to authoritative sources.