Coulometric Titrations with Iodine

Ramsey, W.J.; Farrington, P. S.; Swift, Ernest H.

doi:10.1021/ac60038a031

Cited by 63 publications

(17 citation statements)

References 8 publications

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“…Results obtained by this method compare favorably with results reported for spectrophotometric methods (7) and amperometric, potentiometric, and spectrophotometric titrations (1,8,9). This method combines the versatility of the iodine-iodide redox system with the good accuracy, precision, and sensitivity obtainable by PNPP and eliminates the necessity for maintaining standard thiosulfate and iodine solutions.…”

supporting

confidence: 58%

Micro Range Iodometry by Combining Precision Null-Point Potentiometry and Electrolytic Generation of Iodine

Malmstadt¹,

Pardue²

1960

Anal. Chem.

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supporting

confidence: 58%

Micro Range Iodometry by Combining Precision Null-Point Potentiometry and Electrolytic Generation of Iodine

Malmstadt¹,

Pardue²

1960

Anal. Chem.

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“…by generating chlorine. The data thus obtained were plotted, and the curve of indicator current vs. indicator potential was similar in form to the one obtained by Ramsey for iodine (4), except that the flattest portion of the curve was from 400 to 600 mv.…”

Section: Discussionmentioning

confidence: 69%

Coulometric Titrations with Chlorine Titration of Arsenic and Use of Amperometric End Point

Farrington¹,

Swift²

1950

Anal. Chem.

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“…While such coulometric reagent delivery is a well known approach that dates back more than 50 years [1,2], recent trends in miniaturization and integration of analytical systems have resulted in renewed interest in the technique, especially for the electrogeneration of chemically labile reagents such as bromine or iodine [3].…”

Section: Introductionmentioning

confidence: 99%

Operational Limits of Controlled Current Coulometry with Ion‐Selective Polymeric Membranes

Bhakthavatsalam

Bakker

2008

Electroanalysis

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Plasticized polymeric membrane electrodes containing selective chemical receptors (ionophores) that are used in potentiometric and optical sensors have recently been shown to be attractive in controlled current coulometry for calibration free reagent delivery. For this purpose, a galvanostatic pulse of fixed duration is applied across an ionselective membrane containing added ion-exchanger sites, resulting in the release of a calculated amount of ions from the membrane into the sample phase. This paper evaluates the operational limits of such coulometric actuators with chronopotentiometry, using silver-selective membranes as model systems. Diffusion theory predicts the depletion of ionophore and ion-exchanger at one of the two interfaces in a matter of minutes, owing to the relatively small diffusion coefficients in such membranes. Chronopotentiometry on membranes containing lipophilic cations at either side of the membrane, rather than silver ions, confirms that the ionophore depletes at the inner side of the membrane. At the sample side, ionophore is expected to increase in concentration and does not result in a loss of selectivity. Chronopotentiometric responses show a drastic transition at long times, typically 30 min, which cannot plausibly be explained by the depletion of added lipophilic ion-exchanger at the sample side since the diffusion coefficients are similar to that of ionophore. It is postulated that the intrinsic anion-exchanger sites of the PVC matrix are relatively immobile and do not easily concentration polarize upon application of a transmembrane current pulse, in agreement with Bucks earlier work on fixed site membranes. Indeed, silver and calcium-selective membranes fabricated with increased concentrations of such fixed sites, by using carboxylated PVC, exhibited chronopotentiometric breakdown times larger than 60 min and no loss in coulometric efficiency. The results obtained here will help in designing coulometric actuators with improved characteristics on the basis of hydrophobic polymeric ion-selective membranes.

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Coulometric Titrations with Iodine

Cited by 63 publications

References 8 publications

Micro Range Iodometry by Combining Precision Null-Point Potentiometry and Electrolytic Generation of Iodine

Micro Range Iodometry by Combining Precision Null-Point Potentiometry and Electrolytic Generation of Iodine

Coulometric Titrations with Chlorine Titration of Arsenic and Use of Amperometric End Point

Operational Limits of Controlled Current Coulometry with Ion‐Selective Polymeric Membranes

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