Fe DTPA solution: adding HCL 10%

jonny_ftm

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Mar 5, 2009
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Hi,

Finally, I got my hands on some DTPA Fe 10%, thanks to Rex Grigg.

I'd like a solution with 15g in 500ml of distilled. How much HCl 10% should I add to avoid Fe precipitation/oxidation?
 

Philosophos

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My stock solutions have been happy at 5-6ml/L of HCl. At 10% that would be 50-60ml.
 

Tom Barr

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5-10mls ought to do.
Add this First, then add chelated DTPA after(say 5 minutes or so).

Regards,
Tom Barr
 

jonny_ftm

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Mar 5, 2009
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Many thanks Tom,

Was fearing to add 50ml HCl in my plastic container...

So 10ml in 500ml stock solution or in 1L you mean?
 

Philosophos

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I use 50-60ml all the time without trouble. It raises Cl- by maybe 2-3ppm in a week. I use this much because bad handling practices happen, and I mix my batches for others who may not have much of a grasp of planted tanks or that contamination is a problem.

Tom, I think the 5 minute wait is what I was missing. I was having some very fun issues with chelates when HCl was added first.
 

jonny_ftm

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Mar 5, 2009
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Yes, it is that iron. He told me first it was EDTA. Then, he contacted his reseller that informed him it is DTPA now. I ordered it once he confirmed it is DTPA. But nothing shown on bags, sadely

By the way, anyone knows a way I can differentiate between EDTA and DTPA to be sure of what I have?
 

Philosophos

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EDTA is browin-ish. It'll be the same shade of brown as the darker flecks in CSM+B. DTPA is a nice yellow.

In a stock solution at high concentration, the EDTA seems to stay brown, the DTPA turns a rusty red color.
 

jonny_ftm

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Mar 5, 2009
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You mean really yellow or a yellow brown? Would you post a photo of some DTPA powder please? The Fe I received from Rex looks more like CSM in tint, I'm getting a bit worried here.
 

Philosophos

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Here's a couple pictures from a Chinese supplier:

DTPA-Fe-11.jpg


EDTA:
EDTA-Chelated-IRON-EDTA-Fe-13-.jpg


They've got both under some bright light; mine tends to look a hair darker for both. Still, it gives you a pretty accurate idea.
 
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jonny_ftm

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Mar 5, 2009
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Same for me with Rex, I fully trust him, but he has to rely on his supplier
Looking on the net I saw other photos of DTPA with even a more brownish aspect, adding to the confusion.