Buffer Recipe Calculator

A buffer solution is a mixture that resists changes in pH — used in biology, chemistry, and medicine to keep reactions running at the right acidity. Select your Buffer System (Phosphate, Tris, HEPES, and more), then enter your Target pH, Buffer Concentration, Total Volume, Temperature, and Ionic Strength to get the exact masses of your Primary and Secondary Reagents. Secondary outputs include Calculated pH, Buffer Osmolarity, and Final Volume.

mM
°C
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Results

Primary Reagent Amount

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Secondary Reagent Amount

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Calculated pH

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Buffer Osmolarity

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Final Volume

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Results Table

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Frequently Asked Questions

What is the difference between phosphate and Tris buffers?

Phosphate buffers work best at physiological pH (6.0-8.0) and are commonly used in biological applications. Tris buffers are effective at higher pH ranges (7.0-9.0) and are temperature-sensitive, making them ideal for protein work and molecular biology.

How does temperature affect buffer pH?

Buffer pH changes with temperature due to altered ionization constants. Tris buffer pH decreases by ~0.03 units per °C increase, while phosphate buffers are more temperature-stable with only ~0.003 units per °C change.

What ionic strength should I use for cell culture buffers?

For mammalian cell culture, use physiological ionic strength of ~150 mM, which matches body fluid conditions. Lower ionic strength (50-100 mM) may be suitable for plant cells or specific protein assays.

Can I prepare buffers at different concentrations and dilute them?

Yes, you can prepare concentrated stock solutions (2x, 5x, or 10x) and dilute to working concentration. However, always verify the final pH after dilution, as it may shift slightly from the stock solution pH.

Why is HEPES buffer preferred for cell culture?

HEPES maintains stable pH in CO2-free environments, doesn't interfere with metal ions, and has minimal toxicity to cells. It's ideal for cell culture work where samples are frequently exposed to atmospheric conditions.

How do I adjust buffer pH after preparation?

Use concentrated HCl or NaOH solutions to adjust pH gradually. Add small amounts while stirring and monitoring with a calibrated pH meter. Always adjust pH at your working temperature for accuracy.

What's the shelf life of prepared buffer solutions?

Most buffers are stable for weeks to months when stored properly at 4°C. Phosphate buffers can last 6+ months, while Tris buffers should be used within 1-2 months. Always check pH before use and discard if contaminated.