Calculate the volume of buffer needed to resuspend lyophilized DNA, RNA, or primers to achieve a target molar concentration.
Last updated: March 2026 | By Summacalculator
Nanomoles from tube label or synthesis report
Micromolar (μM) for working stock solution
Enter values and click Calculate
Resuspension is the process of dissolving lyophilized (freeze-dried) biological materials back into solution. This is commonly performed in molecular biology laboratories when receiving synthetic oligonucleotides (DNA/RNA primers), lyophilized plasmid DNA, or dried reagents.
Oligonucleotide manufacturers typically provide the total amount of material in nanomoles (nmol) on the tube label. To create a working stock solution of known concentration, you need to calculate the exact volume of buffer (typically TE buffer or nuclease-free water) to add.
The calculation uses the fundamental relationship C = n/V, where concentration (C) equals moles (n) divided by volume (V). By rearranging to V = n/C, we can determine the required resuspension volume. Standard working concentrations are typically 100 μM for stock solutions, which are then further diluted to 10 μM for working solutions used in PCR and other applications.
V (μL) = n (nmol) / C (μM) × 1000
Where V is volume, n is nanomoles, and C is micromolar concentration
Note: 1 nmol / 1 μM = 1 μL when using these units
You receive a lyophilized PCR primer containing 25 nmol from the manufacturer. You want to create a 100 μM stock solution. How much TE buffer should you add?
Add 250 μL of TE buffer or nuclease-free water to the tube. This creates a 100 μM stock solution. For PCR, you would typically dilute this 1:10 to create a 10 μM working solution.
TE buffer (10mM Tris, 1mM EDTA, pH 8) is recommended for long-term storage as it stabilizes DNA and protects against degradation. Nuclease-free water works for immediate use or if EDTA interferes with downstream applications like PCR.
100 μM is the most common concentration for oligonucleotide stock solutions. This balances reasonable volume (not too dilute) with easy 1:10 dilution to 10 μM working stocks commonly used in PCR protocols.
Store at -20°C for long-term storage (months to years). For frequent use, keep working aliquots at 4°C (up to 2-3 weeks). Avoid repeated freeze-thaw cycles which can degrade oligonucleotides.
Some manufacturers report optical density (OD) units. For DNA: 1 OD260 ≈ 33 μg for single-stranded DNA. You'll need to calculate nmol using the oligonucleotide length and molecular weight. Most provide both values.
Absolutely! The calculator works for any target concentration. Some labs use 200 μM for very concentrated stocks, or 50 μM if the oligonucleotide amount is small. Adjust based on your typical dilution protocols.
Vortexing ensures complete dissolution of the lyophilized material. Brief centrifugation (spin down) brings any solution stuck in the cap down to the bottom, ensuring you have the full calculated volume available.
Use a calibrated pipette with appropriate volume range. For 250 μL, use a P200 or P1000 with fresh tips. Accuracy within ±2% is acceptable for most applications. Avoid extreme volumes (<10 μL or >1000 μL) where errors magnify.
Too much dilutes the concentration (re-calculate actual concentration). Too little makes it more concentrated. If you discover the error immediately, you can add more buffer or concentrate by vacuum centrifugation. Always measure carefully to avoid this.
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