Re: Iron EDTA complex

To: Aquatic-Plants at actwin_com
Subject: Re: Iron EDTA complex
From: psears at NRCan_gc.ca (Paul Sears)
Date: Sat, 6 Apr 1996 19:35:53 -0500 (EST)
In-Reply-To: <199604062039.PAA23399 at looney_actwin.com> from "Aquatic-Plants-Owner at ActWin_com" at Apr 6, 96 03:39:01 pm

> 
> From: ac554 at freenet_carleton.ca (David Whittaker)
> 
> Paul Sears writes...
> >Dave Whittaker wrote...
> >	Why would you expect the UV sterilizer to affect the iron
> >concentrations?  I can't see any reason to expect that.  
> 
> I believe that someone, maybe GB, found that UV use caused his
> iron levels to fall. This makes sense in that it is known that
> light speeds up the breakdown of FeEDTA in solution.
>
	Do you have a reference for that?
  
> 
> From: Elizabeth Worobel <eworobe at cc_UManitoba.CA>
> 
> The formation constant for FeEDTA is 25.1 (log Kmy). The formation 
> constant for Mg is 8.7, for Ca 10.7, for Cu 18.8, and for Zn 16.5 (under 
> standard conditions). As these are log values it is clear that EDTA binds 
> iron MUCH more tightly than any other cation ... I dont think you have to 
> worry about Fe being displaced. Info from Skoog and West, Fundamentals of 
> Analytical Chemistry, 2nd Ed, 1969, p. 345.
> 
> Dr. dave.
>
	Thanks.  At that rate there certainly isn't a problem!


Paul Sears   Ottawa, Canada