Kulture Scientific · Application Note
Choosing the Right Balanced Salt Solution
PBS, DPBS, HBSS, and EBSS look interchangeable but aren't — formulations, sterilization, and when to use each
Kulture Scientific · Application Note
Choosing the Right Balanced Salt Solution
PBS, DPBS, HBSS, and EBSS look interchangeable but aren't — formulations, sterilization, and when to use each
PBS, DPBS, HBSS, and EBSS look interchangeable on a shelf, but they are formulated for different jobs. Picking the wrong one is a common, invisible source of variability — from over-harsh trypsinization to cells acidifying in a CO₂ incubator because the buffer was never designed for that atmosphere.
Why Ca/Mg-free for Trypsin
Calcium and magnesium are cofactors for cadherin- and integrin-mediated adhesion. Cadherin ectodomains are calcium-dependent and unfold without it; integrins need bound divalent cations to hold cell-ECM and cell-cell contacts. Leaving Ca/Mg in the buffer keeps cells stuck together, which works against what trypsin is trying to do.
HBSS and EBSS: Keep Cells Fed, Not Just Rinsed
Both add glucose and bicarbonate, so cells stay viable and attached for longer outside complete medium instead of just being rinsed. The difference between them is how much bicarbonate they carry: HBSS is buffered for open air; EBSS carries about six times more bicarbonate and needs a 5% CO₂ atmosphere to hold pH.
Commercial HBSS/EBSS often add sodium pyruvate alongside or instead of glucose as a second energy source, and can be ordered with or without phenol red — a pH indicator (yellow around pH 6.8, pink/red around pH 8.2) that's usually left out only when it would interfere with fluorescence or absorbance-based assays.
Quick Comparison
| PBS / DPBS | HBSS | EBSS | |
|---|---|---|---|
| Ca²⁺ / Mg²⁺ | No (for wash/trypsin steps) | With or without | With or without |
| Glucose | No | Yes, ~1 g/L | Yes, ~1 g/L |
| Bicarbonate | No | Low | High – needs 5% CO₂ |
| Use it for | Washing, diluting, rinsing before trypsin | Short handling outside the incubator | Short maintenance in a CO₂ incubator |
Water Quality
Formulations
Hydrate form (e.g. CaCl₂ vs CaCl₂·2H₂O) changes the gram weight for the same molarity — confirm what's on your shelf before weighing. HBSS below is verbatim from Current Protocols in Molecular Biology (CPMB), Unit 23.2 (Ca/Mg-free version); EBSS is not in CPMB and is sourced from manufacturer spec sheets, consistent with the original 1943 Earle formulation.
There's no reliably enforced formula difference between these two names. Many published “PBS” recipes (CPMB included, plus widely-used reference recipes) use the exact same salts shown below, KCl included. The one thing “DPBS” more consistently signals is that Ca/Mg is offered as an option — traced back to Dulbecco's 1954 modification — not that it's necessarily present. Check the actual recipe or spec sheet rather than trusting the name.
| NaCl | 8.0 g (137 mM) — tonicity |
| KCl | 0.2 g (2.7 mM) — present in most published recipes, but not universal |
| Na₂HPO₄ | 1.15–2.16 g (hydrate varies by source) — buffer |
| KH₂PO₄ | 0.2–0.24 g — buffer |
| CaCl₂, MgCl₂·6H₂O | 0.1 g each, only if adhesion is wanted — omit for trypsin/wash use |
| Water to | 1000 mL |
| NaCl | 8.0 g (137 mM) — tonicity |
| KCl | 0.4 g (5.4 mM) — ionic balance |
| KH₂PO₄ / Na₂HPO₄ | 0.06 g / 0.048 g — buffer |
| NaHCO₃ | 0.35 g — low-level buffer, open air |
| D-glucose | 1.0 g — energy source |
| CaCl₂, MgSO₄/MgCl₂ | ~0.1–0.2 g each, optional — adhesion / cofactor |
| Water to | 1000 mL |
| NaCl | 6.8 g (117 mM) — tonicity |
| KCl | 0.4 g (5.4 mM) — ionic balance |
| NaH₂PO₄·H₂O | 0.14 g — buffer |
| NaHCO₃ | 2.2 g — primary buffer, needs 5% CO₂ |
| D-glucose | 1.0 g — energy source |
| CaCl₂, MgSO₄·7H₂O | ~0.2 g each, optional — adhesion / cofactor |
When to Use Which
| Task | Use | Why |
|---|---|---|
| Before trypsin, or general wash | PBS/DPBS, no Ca/Mg | Ca/Mg hold cadherin and integrin adhesion together — removing them lets trypsin release cells faster and gentler |
| Holding cells briefly outside the incubator | HBSS, with Ca/Mg + glucose | Keeps cells attached and fed; bicarbonate matches open air |
| Holding cells in a 5% CO₂ incubator | EBSS, with Ca/Mg + glucose | High bicarbonate only buffers correctly under CO₂ |
| Tissue/organ dissociation | HBSS or EBSS per your protocol | Match the specific enzyme and published SOP |
| Washing fixed/attached cells (IF, IHC), diluting ECM coatings | PBS/DPBS, with Ca/Mg | No dissociation intended — Ca/Mg keep adhesion and morphology intact instead of working against them |
| Flow cytometry, immunostaining, IHC/IP | PBS/DPBS, no Ca/Mg, no glucose | Simplest buffer; adhesion and metabolic support aren't the point here |
Sterilization
PBS/DPBS without glucose: autoclave (121°C, standard cycle) or filter — CPMB's own DPBS recipe says either method is validated: “sterilize by filtration or by autoclaving.”
Why Commercial Might Be Better
Getting the formula right is only half the job — lot-to-lot consistency, sterility documentation, and endotoxin testing are easy to underweight when making these in-house. A commercial solution with a Certificate of Analysis removes that variable. Shop balanced salt solutions.
References
1. Current Protocols in Molecular Biology (CPMB). Unit 23.2, “Mouse Embryo Fibroblast (MEF) Feeder Cell Preparation,” Reagents and Solutions. Hoboken, NJ: John Wiley & Sons.
2. Hanks JH, Wallace RE. Relation of oxygen and temperature in the preservation of tissues by refrigeration. Proc Soc Exp Biol Med. 1949;71(2):196–200.
3. Earle WR. Production of malignancy in vitro. IV. J Natl Cancer Inst. 1943;4:165–212.
4. Thermo Fisher Scientific / Gibco. Balanced Salt Solution formulation guide, COL120715 0423. 2023.
For Research Use Only. Not for use in diagnostic or therapeutic procedures.
PBS, DPBS, HBSS, and EBSS look interchangeable on a shelf, but they are formulated for different jobs. Picking the wrong one is a common, invisible source of variability — from over-harsh trypsinization to cells acidifying in a CO₂ incubator because the buffer was never designed for that atmosphere.
Why Ca/Mg-free for Trypsin
Calcium and magnesium are cofactors for cadherin- and integrin-mediated adhesion. Cadherin ectodomains are calcium-dependent and unfold without it; integrins need bound divalent cations to hold cell-ECM and cell-cell contacts. Leaving Ca/Mg in the buffer keeps cells stuck together, which works against what trypsin is trying to do.
HBSS and EBSS: Keep Cells Fed, Not Just Rinsed
Both add glucose and bicarbonate, so cells stay viable and attached for longer outside complete medium instead of just being rinsed. The difference between them is how much bicarbonate they carry: HBSS is buffered for open air; EBSS carries about six times more bicarbonate and needs a 5% CO₂ atmosphere to hold pH.
Commercial HBSS/EBSS often add sodium pyruvate alongside or instead of glucose as a second energy source, and can be ordered with or without phenol red — a pH indicator (yellow around pH 6.8, pink/red around pH 8.2) that's usually left out only when it would interfere with fluorescence or absorbance-based assays.
Quick Comparison
| PBS / DPBS | HBSS | EBSS | |
|---|---|---|---|
| Ca²⁺ / Mg²⁺ | No (for wash/trypsin steps) | With or without | With or without |
| Glucose | No | Yes, ~1 g/L | Yes, ~1 g/L |
| Bicarbonate | No | Low | High – needs 5% CO₂ |
| Use it for | Washing, diluting, rinsing before trypsin | Short handling outside the incubator | Short maintenance in a CO₂ incubator |
Water Quality
Formulations
Hydrate form (e.g. CaCl₂ vs CaCl₂·2H₂O) changes the gram weight for the same molarity — confirm what's on your shelf before weighing. HBSS below is verbatim from Current Protocols in Molecular Biology (CPMB), Unit 23.2 (Ca/Mg-free version); EBSS is not in CPMB and is sourced from manufacturer spec sheets, consistent with the original 1943 Earle formulation.
There's no reliably enforced formula difference between these two names. Many published “PBS” recipes (CPMB included, plus widely-used reference recipes) use the exact same salts shown below, KCl included. The one thing “DPBS” more consistently signals is that Ca/Mg is offered as an option — traced back to Dulbecco's 1954 modification — not that it's necessarily present. Check the actual recipe or spec sheet rather than trusting the name.
| NaCl | 8.0 g (137 mM) — tonicity |
| KCl | 0.2 g (2.7 mM) — present in most published recipes, but not universal |
| Na₂HPO₄ | 1.15–2.16 g (hydrate varies by source) — buffer |
| KH₂PO₄ | 0.2–0.24 g — buffer |
| CaCl₂, MgCl₂·6H₂O | 0.1 g each, only if adhesion is wanted — omit for trypsin/wash use |
| Water to | 1000 mL |
| NaCl | 8.0 g (137 mM) — tonicity |
| KCl | 0.4 g (5.4 mM) — ionic balance |
| KH₂PO₄ / Na₂HPO₄ | 0.06 g / 0.048 g — buffer |
| NaHCO₃ | 0.35 g — low-level buffer, open air |
| D-glucose | 1.0 g — energy source |
| CaCl₂, MgSO₄/MgCl₂ | ~0.1–0.2 g each, optional — adhesion / cofactor |
| Water to | 1000 mL |
| NaCl | 6.8 g (117 mM) — tonicity |
| KCl | 0.4 g (5.4 mM) — ionic balance |
| NaH₂PO₄·H₂O | 0.14 g — buffer |
| NaHCO₃ | 2.2 g — primary buffer, needs 5% CO₂ |
| D-glucose | 1.0 g — energy source |
| CaCl₂, MgSO₄·7H₂O | ~0.2 g each, optional — adhesion / cofactor |
When to Use Which
| Task | Use | Why |
|---|---|---|
| Before trypsin, or general wash | PBS/DPBS, no Ca/Mg | Ca/Mg hold cadherin and integrin adhesion together — removing them lets trypsin release cells faster and gentler |
| Holding cells briefly outside the incubator | HBSS, with Ca/Mg + glucose | Keeps cells attached and fed; bicarbonate matches open air |
| Holding cells in a 5% CO₂ incubator | EBSS, with Ca/Mg + glucose | High bicarbonate only buffers correctly under CO₂ |
| Tissue/organ dissociation | HBSS or EBSS per your protocol | Match the specific enzyme and published SOP |
| Washing fixed/attached cells (IF, IHC), diluting ECM coatings | PBS/DPBS, with Ca/Mg | No dissociation intended — Ca/Mg keep adhesion and morphology intact instead of working against them |
| Flow cytometry, immunostaining, IHC/IP | PBS/DPBS, no Ca/Mg, no glucose | Simplest buffer; adhesion and metabolic support aren't the point here |
Sterilization
PBS/DPBS without glucose: autoclave (121°C, standard cycle) or filter — CPMB's own DPBS recipe says either method is validated: “sterilize by filtration or by autoclaving.”
Why Commercial Might Be Better
Getting the formula right is only half the job — lot-to-lot consistency, sterility documentation, and endotoxin testing are easy to underweight when making these in-house. A commercial solution with a Certificate of Analysis removes that variable. Shop balanced salt solutions.
References
1. Current Protocols in Molecular Biology (CPMB). Unit 23.2, “Mouse Embryo Fibroblast (MEF) Feeder Cell Preparation,” Reagents and Solutions. Hoboken, NJ: John Wiley & Sons.
2. Hanks JH, Wallace RE. Relation of oxygen and temperature in the preservation of tissues by refrigeration. Proc Soc Exp Biol Med. 1949;71(2):196–200.
3. Earle WR. Production of malignancy in vitro. IV. J Natl Cancer Inst. 1943;4:165–212.
4. Thermo Fisher Scientific / Gibco. Balanced Salt Solution formulation guide, COL120715 0423. 2023.
For Research Use Only. Not for use in diagnostic or therapeutic procedures.