On the lab bench and in field kits alike, keeping pH steady makes experiments reliable and results reproducible. Whether you’re preparing enzyme assays, running electrophoresis, or teaching a chemistry class, having a go-to list of buffers saves time and reduces guesswork.
There are 20 Examples of Buffer Solutions, ranging from Acetate to Tris. For each entry you’ll find below Conjugate pair,pKa (25°C),Effective pH range (pH) so you can quickly match a buffer to your target pH and conditions — you’ll find below the complete list and data for easy reference.
How do I pick the right buffer for a specific pH?
Choose a buffer whose pKa is within about ±1 pH unit of your target pH so it can resist changes effectively; also consider ionic strength, temperature sensitivity, and any chemical interactions with your assay (for example, avoid phosphate with some metal-dependent enzymes).
Are these buffers stable over time and temperature?
Stability varies: many common buffers are stable at room temperature for weeks, but some (like Tris) show temperature-dependent pKa shifts and others can decompose or support microbial growth—store appropriately, use fresh stock for critical work, and check supplier notes for storage recommendations.
Examples of Buffer Solutions
| Name | Conjugate pair | pKa (25°C) | Effective pH range (pH) |
|---|---|---|---|
| Phosphate | H2PO4- / HPO4^2- | 7.21 | 6.2-8.2 |
| Acetate | Acetic acid / Acetate | 4.76 | 3.6-5.6 |
| Tris | Tris‑HCl / Tris base (Tris(hydroxymethyl)aminomethane) | 8.07 | 7.0-9.0 |
| HEPES | HEPES / HEPES‑H+ | 7.55 | 6.8-8.2 |
| MES | MES / MES‑H+ | 6.15 | 5.5-6.7 |
| MOPS | MOPS / MOPS‑H+ | 7.20 | 6.4-7.8 |
| PIPES | PIPES / PIPES‑H+ | 6.76 | 6.1-7.5 |
| Citrate | Citric acid / Citrate | 4.76 | 3.0-6.2 |
| Carbonate | H2CO3 / HCO3- | 6.37 | 6.0-8.3 |
| Borate | Boric acid / Borate | 9.24 | 8.0-10.0 |
| Glycine | Glycine (COOH/NH3+ zwitterion) — COOH pKa 2.35 NH3+ pKa 9.60 | 9.60 | 2.0-3.5 and 8.6-10.6 |
| Ammonium | NH4+ / NH3 | 9.25 | 8.2-10.2 |
| Lactate | Lactic acid / Lactate | 3.86 | 3.1-5.1 |
| Formate | Formic acid / Formate | 3.75 | 2.8-4.8 |
| Succinate | Succinic acid / Succinate | 4.21 | 3.2-5.2 |
| TES | TES / TES‑H+ | 7.50 | 6.5-8.5 |
| CHES | CHES / CHES‑H+ | 9.31 | 8.3-10.3 |
| CAPS | CAPS / CAPS‑H+ | 10.40 | 9.6-11.2 |
| TAPS | TAPS / TAPS‑H+ | 8.40 | 7.7-9.1 |
| Tricine | Tricine / Tricine‑H+ | 8.15 | 7.4-8.8 |
Images and Descriptions
Phosphate
Widely used 10–100 mM laboratory and biological buffer for enzymatic assays, cell culture and chromatography. Easy to prepare from NaH2PO4/Na2HPO4, inexpensive and inert, but forms insoluble salts with divalent cations and has temperature-dependent pKa.
Acetate
Common 10–200 mM buffer for protein purification, microbial media and HPLC mobile phases. Prepared from acetic acid and sodium acetate; cheap and effective near pH 4–5 but can inhibit some enzymes and has limited buffering above pH 5.
Tris
Very common 10–100 mM biological buffer (molecular biology, electrophoresis) with strong temperature dependence of pKa (~−0.03 pH/°C). Easy to prepare but reacts with aldehydes and is not ideal for metal-binding studies.
HEPES
A Good’s buffer used at 10–50 mM for cell culture, enzyme assays and spectroscopy; low metal binding and minimal temperature sensitivity. Prepare from HEPES free acid and NaOH/HCl. More expensive than phosphate, can absorb at UV below 230 nm.
MES
Popular 10–50 mM biological buffer for biochemical assays at mildly acidic pH. Low reactivity with metal ions, suitable for cell work; prepare from MES acid and base. Not ideal above pH 7 and can chelate some cations weakly.
MOPS
Used 10–50 mM for protein chemistry, electrophoresis and cell culture near neutral pH. Good temperature stability and low UV absorbance; prepare from MOPS free acid and NaOH. More costly than phosphate; weak interactions with metals.
PIPES
10–50 mM buffer suited to cell biology and enzyme work at near-neutral pH with low cell toxicity. Prepare from PIPES acid and base. Limited buffering above pH 7.5 and relatively expensive for large volumes.
Citrate
Used 10–100 mM for biological assays, anticoagulant solutions and food industry; prepared from citric acid and sodium citrate. Effective in acidic range, chelates metal ions and can inhibit metalloproteins; useful for antigen retrieval and pH adjustments.
Carbonate
Physiological buffer for cell culture and blood-gas equilibria, often as 10–50 mM bicarbonate with CO2 atmosphere. Easy and inexpensive but pH is CO2-dependent and not suitable for open systems without CO2 control.
Borate
Used 5–100 mM in electrophoresis, enzyme assays and as antiseptic; prepare from boric acid and NaOH. Good for alkaline buffering but forms complexes with cis‑diols (sugars, nucleotides) and can inhibit some enzymes.
Glycine
Versatile amino‑acid buffer used 10–200 mM at acidic or basic pH endpoints. Prepare from glycine with acid or base; inexpensive and useful in electrophoresis, but ionic strength and zwitterionic behavior affect protein interactions.
Ammonium
Used mainly 10–100 mM in industrial and biochemical contexts where volatile buffering is acceptable. Prepared from ammonium salts and ammonia; useful for pH control where removal by volatilization is desirable, but toxic at high concentrations.
Lactate
10–100 mM buffer common in physiological and fermentation studies, suitable for low pH work and metabolic assays. Made from lactic acid and lactate salts; biologically relevant but metabolized by cells and interacts with NAD+/NADH pathways.
Formate
Used 10–200 mM in chromatography, protein work and small‑molecule chemistry at acidic pH. Easy to prepare from formic acid and sodium formate; corrosive and can be toxic at high concentrations, limiting biological use.
Succinate
10–100 mM buffer for metabolic studies and enzyme assays in the acidic range; prepare from succinic acid and sodium succinate. Biologically relevant as a TCA intermediate but can be metabolized by cells and chelate metals weakly.
TES
Good’s buffer used 10–50 mM in biochemical assays and cell studies near neutral pH. Low metal binding and stable; prepare from TES acid/base. More costly than classical buffers and less common for very large volumes.
CHES
20–100 mM buffer for alkaline enzyme assays and protein work. Good for reactions needing high pH with low reactivity; prepared from CHES acid and base. Limited use in biological systems sensitive to high pH.
CAPS
High‑pH buffer (10–100 mM) for industrial enzyme reactions and alkaline separations. Stable and low reactivity but costly and not suitable for biological systems needing physiological pH.
TAPS
10–100 mM buffer used in molecular biology and enzymology near alkaline-neutral pH. Low metal binding and stable; prepare from TAPS acid/base. Useful when Tris or HEPES are unsuitable due to reactivity or temperature sensitivity.
Tricine
Common 10–100 mM buffer for electrophoresis and enzymology at slightly alkaline pH. Low UV absorbance and good for peptide work; prepare from tricine acid and NaOH. Not ideal above pH 9 and can interact with some proteins.
