I This study was initiated to find a suitable niethod for analjAing chelating agents in general and also nietal chelates. The method can be used for determining mixtures of chelating agents and, in reverse, for determining metals and mixtures of certain metals. The general approach is the potentiometric titration of the chelating agent with a metal ion (or vice \ersa) using an electrode system that indicates an) excess of metal ion in the system. Conditions, metal ion, and electrode ')stems can be varied so that mixtures of chelating agents can be determined. The chelating agent, coiiditions, and electrode s>stern can be varied so that niixtures of metal ions can be determined. Metal chelates ran also be analyzed for unchelated metal ion present, excess chelating agent, and the amount of metal chelate present. The method is simple to apply, and the precision and accuracy are generally better than =kly' for the SJ stems where good titration cur\es are obtained. H1:IATIIVC; ageiitt have iouud their way into iiicin~ di-C verse applications. The nuniber of chelating agents in nse in industry has increased beyond the ell-known ethylenedianiinetetia,wetic acid [ E D T h ; also known as (ethylenedinitri1o)-teti aacetic arid]. Induqti y no\\-employs mixtures of chelating agents to achieve certain desirable characteristics. Metal chelates have become industrially important in recent years, esprrially in the agricultural field. This diversification of applicatioiis and the increase in the scope of chelation chemistry have necessitated the development of analytical methods to folloii the proresses and investigations being carried ollt.Chelating agents have, in recent years, become of great importance from the standpoint of analysis. Biedermann and dchw arzenbech ( I ) devised a method for determining various nictallic ions with EDTA. involving the use of a special indicator. The procedure can be reversed to determine EDTA by titrating nith magnesium ion. The piocedure cannot be applied to porn(' of the other chelating agents n hich are produced today.Furness, Cramhaw, and Davies (6) determined EDTA polarogi 'iphically. Blaedel, Knight, and Malmstadt (2-4) used high frequency titration of metal ions I\ ith E D T I . Laitinen and Sympson ( 9 ) employed anipeiomctric titrations, and Hall and others ( 7 ) rmd conductonietric titiations.Pfihil, Iioudela, and 11atyska (IO) used potentiometrir titrationq for determining 11011 by direct titration n ith CDT-3. solution. Platinum was used as the indicating elertrode in an aqnrous medium. Iron was the only metallic ion that could be cietei mined directly. Aluminum, copper, cadmium, zinc, nickel. lead. and bismuth were a190 determined, but indirectly, bi addition of cxcesb EDTA and back-titration of the excess nith a standard solution of ferric chloride.I t was found that by varying the solvents and especiall? the electrodes employed, the potentiometric approach described by Pfibil could be evtended not only to the direct titration of a nun1 ber of metals other than iron but also to th...

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