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How to Make an Iron Chelate

Chelating agents like oxalate and EDTA bind to a metal ion at multiple sites with high affinity, so they're a good way to remove metal ions from solution. You can apply chelated iron (iron bound to a chelating agent) to treat a plant disorder called chlorosis; it's also useful for preparation of plant tissue culture. You can prepare iron chelate in the lab using two chemicals, iron (II) sulfate heptahydrate and ethylenediaminetetraacetic acid, better known as EDTA.

Things You'll Need

Lab coat, goggles, gloves (wear these throughout procedure)
Graduated cylinder
Tissue-culture grade deionized water
2 beakers
Scale
Plastic weigh boats
Iron (II) sulfate heptahydrate
Glass stir rod
Disodium EDTA
Funnel
1 liter volumetric flask

Instructions

- 1
  Measure out 350 mL of tissue-culture grade water and add it to the first beaker using your graduated cylinder. Do the same for the second beaker.
- 2
  Weigh 0.278 grams of iron (II) sulfate heptahydrate on a plastic weigh boat placed on the scale. Remember to zero out the scale first so that you don't take the plastic weigh boat into account. Pour this material into the first beaker and stir to dissolve.
- 3
  Weigh out 0.3725 grams of disodium EDTA on another weigh boat and add it to the second beaker. Clean off your glass stir rod then stir to dissolve.
- 4
  Heat the beakers on a hot plate to help dissolve the solids if they fail to fully dissolved.
- 5
  Add the contents of both beakers to the volumetric flask using a clean funnel. Rinse the inside of the beakers with tissue-culture grade water to remove any lingering solution and pour the rinse water into the volumetric flask as well.
- 6
  Add more tissue-culture grade water until the level in the volumetric flask reaches the fill line. Remember to look at the bottom of the meniscus (the curved dimple in the surface of the water) when measuring the level.
- 7
  Cap the volumetric flask and invert it to mix, then store it in an appropriate location in your lab. Dilute before use as appropriate for the experiment you plan to perform.

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