Amperometric Titration of Two- and Three-Component Mixtures of Metal Ions with (Ethylenedinitrilo)-tetraacetic Acid

Reilley, Charles N.; Scribner, William G.; Temple, Carrol.

doi:10.1021/ac50161a012

Cited by 63 publications

(7 citation statements)

References 4 publications

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“…The tertiary amines of EDTA form weak coordination bonds with MI O (except Al 3+ and Y 3+ ) so that it can be oxidized easily by electrogenerated Ru(bpy) 3 3+ . [19][20][21][22] In the present investigation, the concentration of Ru(bpy) 3 2+ was at least 20 times larger than that of EDTA, which is sufficient to keep the ratio of Ru(bpy) 3 3+ to amine higher than the stoichiometric ratio (2+1) in the presence of MI O , which results in the consumption of the electrogenerated Ru(bpy) 3 3+ for the oxidation of EDTA. 13 This maintains the signal without any change on addition of MI O .…”

Section: Discussionmentioning

confidence: 87%

“…The tertiary amines of EDTA form strong coordination bonds with MI N so that it cannot be oxidized by electrogenerated Ru(bpy) 3 3+ . [19][20][21][22] This results in a decrease in the ECL intensity in the presence of MI N . Al 3+ and Y 3+ have higher positive charges than Mg 2+ and Ca 2+ and smaller atomic diameters than Ce 3+ , Nd 3+ , Sm 3+ and La 3+ .…”

Section: Discussionmentioning

confidence: 99%

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Effect of metal ions on Ru(bpy)32+ electrochemiluminescence

Xu¹,

Dong²

1999

Analyst

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Ethylenediaminetetraacetate (EDTA) was chosen for the investigation of the effect of metal ions on Ru(bpy) 3 2+ electrochemiluminescence (ECL). Metal ions that are preferentially bound to the oxygen atoms (MI O ) have no effect on the intensity of ECL except for Al 3+ and Y 3+ , whereas metal ions that are preferentially bound to the nitrogen atoms (MI N ) preclude the oxidation of EDTA and decrease the ECL intensity.

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Section: Discussionmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Effect of metal ions on Ru(bpy)32+ electrochemiluminescence

Xu¹,

Dong²

1999

Analyst

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“…According to Michel, the rate of dissociation of metal-EDTA complexes is proportional to hydrogen ion concentration (28). Reilley et al found that at pH 4 equilibrium was established sufficiently rapidly on the time scale of DC polarography that sequential titration of, e.g., Fe(III) and Mn(II) could not be carried out (29). However amperometric titrations of Cd(II)…”

Section: Resultsmentioning

confidence: 99%

Direct determination of chelons at trace levels by one-drop square-wave polarography

Stojek¹,

Osteryoung²

1981

Anal. Chem.

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The direct anodlc oxldaitlon of mercury In the presence of chelons can be used for determinatlon of the chelons at trace levels. One-drop square-wave polarography proved superior to dlfferential pulse polalrography for thls purpose and gave detection limits of 7, 7, 5, and 20 X IO-* M for EDTA, DCTA, EGTA, and NTA, respecttvely, with callbratlon curves linear to M. At pH 4.8 heirvy metals can be determlned In the presence of Ca2+ by using amperometrlc titratton based on this method.Chelons such as EDTA (ethylenediaminetetraacetic acid) are used in a wide range of industrial, pharmaceutical, and agricultural applicationa. It has been shown that EDTA is resistant to biodegradation ( I ) . It has also been shown that under the conditions normally obtaining in natural waters EDTA exists as negatively charged complexes with protons or metal ions and is not (absorbed on container walls, humic acid, silica, kaolin, river sediments, or humus solids (1). Gardiner infers from the existing data that complexation of trace metals in natural waters by EDTA 1s more important than complexation by humic acids ( I ) . A simple numerical example illustrates this point. With the data of Buffle and Greter (2), the overall conditional formation constants for Pb(I1) with fulvic acid (molecular weight nominally 1000) at pH 6 are given by log PI = 5.1 and log 02 := 9.7 for the complexes PbL and PbLz, where L represents fulvic acid. At the same pH the conditional iformation constant for PbY is given by log K' = 13.4, where represents EDTA. Suppose that Cy, the analytic concentration of Y, is 100 pg/L. K' is sufficiently large that the fraction of lead present as the aquated ion is negligible as long a8 the analytic concentration of lead, Cp,, is less than that of Y. Under these conditions, the fraction of lead complexed with L, is less than 0.1 for concentrations of L less than 7 g/L (7 mF). Similar conclusions are drawn for other cases. Gardiner h a carried out similar calculations which include the effects of competition of Ca(I1) for EDTA and illustrate some limitations of this generalization (1). Undoubtedly EDTA is capable of affecting natural systems to an appreciable extent by mobilizing trace metals.A variety of methods have been employed for the determination of EDTA and related compounds. Gardiner used gas-liquid chromatograplhy of the ethyl derivatives of the sample with DCTA (1,2-cyclohexanediaminetetraacetic acid) added as an internal standard for the determination of EDTA in river water, sewage, arid sewage effluent (3). Detection limits of ca. 5 X M (15 pg/L) with recoveries of ca. 99 f 13% were found with a sample size of 25 mL. Kaiser employed the absorbance of the Co(II1) complex and was able to determine EDTA in mixtures of EDTA and NTA (nitrilotriacetic acid) by selective oxidation of the NTA complex (4). Replicate analyses at the 200 pg/L level of EDTA in mixtures of EDTA and NTA gave precision of 7% (standard Present address: Uniwersiytet Warszawski, Wydzial Chemii, ul. Pasteura 1,02493 Warszawa,, Poland. deviation)....

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“…For all the measurements we used a dropping mercury electrode with an m value of 1.240 mg/sec and a drop time td of 4.80 sec at a mercury height of 60 cm in an 4.80 at -0.60 V vs. SCE.…”

Section: Methodsmentioning

confidence: 99%

Polarographic Behavior of Diethylenetriaminepentaacetic Acid at the Dropping Mercury Electrode

Kodama¹,

Kimura²

1967

Bulletin of the Chemical Society of Japan

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Anodic waves of DTPA at DME in the presence and in the absence of calcium(II) and magnesium(II) ions were studied systematically, and the stability constants of mercury(II)-DTPA chelates were determined. The electrode reaction for the anodic waves of DTPA proceeds reversibly in a polarographic sense. In the presence of magnesium(II) ions, however, DTPA gives an irreversible wave. This may be ascribed to the slow reaction of the magnesium(II)-DTPA chelate. The use of DTPA as a titrant in the amperometric titration of metal ions which do not yield a polarographic wave under the usual polarographic conditions was also discussed briefly.Many works on the chelate formation reaction of diethylenetriaminepentaacetic acid (DTPA) with mercury(II) ions have been published.1-3) In an acid medium, DTPA forms 1-to-1 normal and hydrogen chelates with mercury(II) which are considerably more stable than the corresponding mercury(II)-EDTA chelates. This can be attributed to the increased number of donor atoms present and to the more basic character of DTPA.2)As in the case of EDTA,4) DTPA gives rise a single well-defined anodic wave at the dropping mercury electrode (DME). The present work was undertaken in an attempt to obtain insight concerning the electrode reaction mechanism of DTPA anodic waves in the presence and in the absence of calcium(II) and magnesium(II) ions, and to study the complexation reaction of DTPA with mercury-(II) by the polarographic method.The use of DTPA as a titrant in the amperometric determination of calcium(II) and lanthanum(III), which do not yield a reduction wave under the usual polarographic conditions, was also examined. ExperimentalAll polarographic studies were carried out in anThe ionic strength of the solution was adjusted by adding appropriate amounts of sodium perchlorate. The oxygen dissolved in the sample solution was removed by bubbling pure nitrogen gas through the solution. The d.c. current-voltage curves were measured by a manual polarograph similar to that of Kolthoff andLingane5)The a.c. and d.c. polarograms were recorded automatically by a Yanagimoto Galvarecorder GA-103. The d.c. polarographic data given in this paper were corrected for the residual current and the ohmic drop of the cell circuit.For all the measurements we used a dropping mercury electrode with an m value of 1.240 mg/sec and a drop time td of 4.80 sec at a mercury height of 60 cm in an 4.80 at -0.60 V vs. SCE.A saturated calomel electrode with a large surface area was used as the reference electrode.When the a.c. polarograms were recorded, a platinum wire electrode with a large surface area was inserted into the electrolytic solution as a third electrode. in order to minimize the impedance of the cell.6) DTPA of analytical reagent grade was recrystallized from an aqueous solution by adding an excess amount of hydrochloric acid, and dissolved into the redistilled water by neutralizing it with a suitable amount of sodium hydroxide. The concentration of the DTPA solution was checked by Mg titration, using Eriochrom ...

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Amperometric Titration of Two- and Three-Component Mixtures of Metal Ions with (Ethylenedinitrilo)-tetraacetic Acid

Cited by 63 publications

References 4 publications

Effect of metal ions on Ru(bpy)32+ electrochemiluminescence

Effect of metal ions on Ru(bpy)32+ electrochemiluminescence

Direct determination of chelons at trace levels by one-drop square-wave polarography

Polarographic Behavior of Diethylenetriaminepentaacetic Acid at the Dropping Mercury Electrode

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