Estimate osmolarity changes when adding solutes to cell culture media. Get adjustment recipes for mammalian cell target ranges. Data never leaves your browser.
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Add water to dilute
Add ~100 mL sterile water per liter of solution to reach ~300 mOsm/kg. Verify with osmometer.
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Osmolarity is calculated as the sum of all osmotically active particles in solution:
Where i is the van’t Hoff dissociation factor. For strong electrolytes like NaCl, i 1.86 (ideal would be 2.0, reduced by ion pairing). For non-electrolytes like glucose, i = 1.0.
This is an estimate. For precise osmolarity measurement, use a freezing point depression or vapor pressure osmometer.
Commercial media are formulated to specific osmolarity ranges:
• DMEM: ~330 mOsm/kg (higher due to glucose content) • RPMI-1640: ~300 mOsm/kg • MEM: ~290 mOsm/kg • DMEM/F-12: ~310 mOsm/kg
Adding supplements (antibiotics, amino acids, HEPES buffer) will increase osmolarity. Plan additions carefully to stay within the target range.
