[kouxoukouxou]

Hi
I want to feed 57Fe to lab mice to use it as a tracer. I have high purity metallic 57Fe but I want to convert it to ferrous sulfate FeSO4 because it has better absorption from the body and then use it as a supplement in their food.

My chemistry background is limited, so I would like your help on how to convert the metallic iron to FeSo4. I would like it to be as pure as possible, and limit the 57Fe losses to minimum as it is very expensive.

If I dissolved the metallic 57Fe into 98% H2SO4 and then use NaOH to adjust the PH to 7, will this do the trick?

Thanks in advance

[Burner]

If I dissolved the metallic 57Fe into 98% H2SO4 and then use NaOH to adjust the PH to 7, will this do the trick?

You will likely get Fe₂(SO₄)₃. You may need to check if it is well-absorbed by the body.

[Arkcon]

Do check the label on a bag of mice chow, or do an internet search the the form that is best absorbed by mice.  And then we can see about replicating the nutrient in that form.  Getting the pH back to a proper level is useful, but NaOH, although it would work chemically, may not keep the iron in the form you want. 

When we prepare bacterial media, or hydroponic plant media, we typically use buffers to get the correct pH, you should probably do the same for animal feed.  Except, you don't often hear about people preparing their own animal feed supplements.  If you do it very wrong, the animals will reject it, and go hungry.  Or they won't notice, and maybe die.  That's messier than dying plants or bacterial culture.  You really do have to look up some sort of journal article on this topic.

[kouxoukouxou]

Thanx for your replies.

Unfortunately the mice must be enriched with ⁵⁷Fe isotope, so the only way to do this is by manually supplement their food. I checked some mice diets, and they add supplements to them. 2 of them are Iron Sulfate - heptahydrate, and Ferric Citrate (for humans they use Ferric Ammonium Citrate). Also i think I can use ferrous gluconate and ferrous fumarate (they are both used in human supplements along Ferrous sulfate).

In a paper i found, they used this recipe to enriched the mice (but it was with oral administration, which is not suitable for our project): "A 0.4 mol/L solution of ⁵⁷FeSO4 was prepared by overnight dissolution of 22.85 g ⁵⁷Fe/L in 0.4 mol/L H2SO4, The obtained ⁵⁷FeSO4 solution was stored at 4 C. Before its use, 87.7 mg sucrose and 0.83 mg ascorbic acid per mg iron were added to the ⁵⁷FeSO4 solution to yield a final concentration of 20 mol/L ⁵⁷Fe, 5.38 mmol/L ascorbic acid and 10% sucrose. The solution was adjusted to pH7 by adding the required volume of 1 mol/L NaOH."

[Arkcon]

Off hand, the citrate salt is better.  Iron forms a complex with citrate, and will maintain the complex at typical animal physiological pH.  Getting iron to dissolve in citric acid isn't so trivial,you may have to invest in a way to grind it into filings. 

And I do like your reference procedure. Maybe its better not to spike their food, and possibly was some on reaction, or loss, or spillage.  But instead, prep the oral solution with sucrose.  They won't mind being picked up, once they know you're going to give them droplets of sugar water.

Note:  you started this thread with 98% sulfuric and then "some" NaOH.  Notice your reference uses 0.4 M and a few drops of 1 N NaOH. Take the hint and go for smaller volumes of less concentrated reagents.  Note: they don't try to pH adjust the stock solution, instead, they adjust the dilute solution at point of use.  You will get precipitation otherwise, which is likewise a waste.

[kouxoukouxou]

Off hand, the citrate salt is better.  Iron forms a complex with citrate, and will maintain the complex at typical animal physiological pH.  Getting iron to dissolve in citric acid isn't so trivial,you may have to invest in a way to grind it into filings. 

And I do like your reference procedure. Maybe its better not to spike their food, and possibly was some on reaction, or loss, or spillage.  But instead, prep the oral solution with sucrose.  They won't mind being picked up, once they know you're going to give them droplets of sugar water.

Note:  you started this thread with 98% sulfuric and then "some" NaOH.  Notice your reference uses 0.4 M and a few drops of 1 N NaOH. Take the hint and go for smaller volumes of less concentrated reagents.  Note: they don't try to pH adjust the stock solution, instead, they adjust the dilute solution at point of use.  You will get precipitation otherwise, which is likewise a waste.

Unfortunately the oral administration is not possible because the mice must accumulate the iron over time (as they do in normal situations). Feeding 15+ mice every day through oral administration for a period of 9-12 months is not easy. So the best possible scenario is to make iron solution (FeSO4), spray it in Fe-deficient diet powder, mix it with water and make " diet cookies" for them to eat.