Description
🔗 EDTA Disodium (Na₂EDTA) — the chelating agent that makes iron available in TC media. Fe-EDTA is the standard iron source in MS and most modern media — without it, iron precipitates at culture pH and becomes unavailable.
| 🧪 CAS | 6381-92-6 | ⚖️ MW | 372.24 g/mol |
| 🔬 Grade | TC / Analytical | 🌡️ Storage | RT, dry, sealed |
🔗 Why iron needs EDTA
At the working pH of TC medium (5.7–5.8), free iron (Fe³⁺) precipitates as Fe(OH)₃ — essentially insoluble. Complexed with EDTA as Fe-EDTA, iron remains in solution and is released to plants via chelate reductase activity at the root surface. Pre-formed Fe-EDTA (FeSO₄·7H₂O + Na₂EDTA, boiled together) is standard in MS preparation.
⚗️ Uses
| Use | Concentration | Notes |
|---|---|---|
| Fe-EDTA stock preparation | 5.57 g FeSO₄·7H₂O + 7.45 g Na₂EDTA per litre | Boil together, store at 4 °C in dark |
| MS medium iron supplement | 100× stock at 5 mL/L final (≈100 µM Fe-EDTA) | Standard MS iron level |
| Media reformulation / custom media | Equimolar to FeSO₄ used | Na₂EDTA : FeSO₄ = 1.34 : 1 by weight |
| Heavy metal chelation experiments | Variable | Chelate-free baseline comparisons |
💡 Always prepare Fe-EDTA stock by boiling Na₂EDTA and FeSO₄ together — do not add them separately to the medium. The chelate must form before the medium is made up or iron precipitates at autoclave pH.
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