Single drop square wave polarography

Ramaley, Louis; Tan, Wee Tee

doi:10.1139/v81-493

Cited by 13 publications

(10 citation statements)

References 8 publications

(18 reference statements)

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“…identically for the scheme of eq. [24] and toward positive values and to a greater extent for eq. [25], as shown in Table 2.…”

Section: Results Derived From Theorymentioning

confidence: 85%

“…The method used by Rifkin and Evans (23) for pulse methods is quite general and provides results for any sequence of pulses with no restrictions on time symmetry or amplitude. Ramaley and Tan (24) have extended the treatment to include the expanding plane geometry and both average and instantaneous current. For the case of a stationary spherical electrode, presented in detail in the appendix, a general equation is developed for any pulse sequence.…”

Section: Theorymentioning

confidence: 99%

“…The equations for the currents flowing to a stationary, planar electrode on the jth half-cycle of the square wave are (21)(22)(23)(24): i…”

Section: Theorymentioning

confidence: 99%

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Cyclic single drop square wave polarography at spherical electrodes — the reversible case

Ramaley¹,

Tan²

1987

Can. J. Chem.

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Louis RAMALEY and WEE TEE TAN. Can. J. Chem. 65, 1025Chem. 65, (1987.The influence of electrode sphericity and the results of sweep reversal are examined for square wave voltammetry and the square wave polarography in which an entire polarogram is obtained on a single drop. An expanding sphere treatment obtained by adding a spherical correction to expanding plane theory gives the best fit to the experimental data. Amalgam forming reactions fit the simple theory developed to a lesser extent than other reactions, especially on the reverse sweep. The shape of the differential polarogram is not significantly affected by sphericity and the reverse peak potential is approximately equal to the forward peak potential. Small differences in these potentials are due to the distortion of the square wave by the stairstep used for the sweep and the distortion of the polarogram due to drop growth. The ratio of the forward and reverse peak currents depends on the phasing of the square wave and stairstep in all cases and on other parameters for a growing drop.LOUIS RAMALEY et WEE TEE TAN. Can. J. Chem. 65, 1025 (1987) On a examint l'influence de la sphtricite de I'tlectrode et les rtsultats de l'inversion du balayage sur la voltametrie onde carrte et sur la polarographie a onde carrte dans lesquels le polarogramme complet est obtenu sur une goutte unique. Le meilleur accord avec les donntes exptrimentales est obtenu en utilisant un traitement de sphere en expansion, qui est obtenu par l'addition d'une correction spherique a la thtorie du plan en expansion. Les rtactions qui conduisent a un amalgame se produisent a un degrC moindre que les autres rtactions, principalement lorsqu'on renverse la balayage, et elles peuvent &tre expliqutes par la thtorie simple qui a Ct& d&veloppte. La forme du polarogramme differentiel n'est pas affectte d'une fason importante par la sphiricitt et le potentiel maximum de la reaction inverse est approximativement egal au potentiel maximum de la rtaction normale. Les petites differences observees dans ces potentiels sont dues a la distortion de la vague carrte par les tchelons utilists pour le balayage ainsi qu'a la distortion du polarogramme qui est causee par la croissance de la goutte. Le rapport des courants maxima normaux et inverses depend de la phase de la vague carrke et de l'tchelon dans tous les cas et sur d'autres paramktres d'une goutte qui croit.[Traduit par la revue]

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“…identically for the scheme of eq. [24] and toward positive values and to a greater extent for eq. [25], as shown in Table 2.…”

Section: Results Derived From Theorymentioning

confidence: 85%

Section: Theorymentioning

confidence: 99%

See 1 more Smart Citation

Cyclic single drop square wave polarography at spherical electrodes — the reversible case

Ramaley¹,

Tan²

1987

Can. J. Chem.

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“…The computer-controlled potentiostat and cell system used have been previously described (16). All potentials were measured versus the saturated calomel reference electrode and experiments were carried out between 23 and 25°C.…”

Section: Apparatusmentioning

confidence: 99%

“…play a part will be diffuse rather than sharp, especially if the adsorption is not particularly strong, one would expect diffusion effects to begin to be observed at concentrations somewhat less than 3 x M. For a reversible, diffusion controlled SDSWP experiment (16) with all parameters except electrode area held constant and with all parameters except square wave halfperiod. r , held constant…”

mentioning

confidence: 99%

Adsorption enhancement in square wave polarography

Ramaley¹,

Dalziel²,

Tan³

1981

Can. J. Chem.

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Lours R A V~L E Y . JOHN A. DALZIEL, and WEE TEE TAN. Can. . I . Chem. 59, 3334 (1981).Reduction peaks in single drop square wave polarography (SDSWP) for metal ions such as Cd(1I) and Pb(I1) in the preience of picolinic acid gave peak currents that can be an order of magnitude or more greater than diffusion-limited peaks. Various studies using techniques such as controlled-potential electrolysis. tast polarography. staircase voltammetry. and SDSWP demonstrated that this enhancement effect was due to the adsorption of metal-picolinate complexes on the electrode surface. Since it provides a detection limit of about 0.2 ppb with ions such as Cd(I1). adsorption enhancement appears to be of use in trace analysis under certain circumstances. Linearity is observed only up to 1 x 10-'.M and any substance capable of adsorption is a potential inte~ferent. LOUIS RAMALEY. JOHN A. DALZIEL et WEE TEE TAN. Can. J. Chem. 59, 3334 (1981). Les pics de reduction dans la polarographie a onde carree sur goutte pendante (POCGP) d'ions metalliques tels le Cd(I1) et le Pb(I1) en presence de I'acide picolinique donnent des courants de pointe qui peuvent plus grands que les pics limites par la diffusion par un ordre de grandeur ou plus. Plusieurs etudes utilisant des techniques comrne I'electrolyse a potentiel controle. la polarographie echantillonnke. la voltamerie i impulsions surimposes d'amplitudes croissantes et la POCGP ont demontre que cet effet d'augmentation est due a I'adsorption des complexes picolinate-metal la surface de I'electrode. Puisqu'elle fournit une limite de detection de 0.2 ppb avec des ions comme le Cd(I1). I'augmentation de l'adsorption apparait utile dans I'analyse des traces dans certaines circonstances. On observe une linearite seulement jusqu'a I x M et toute substance capable d'adsorber pourrait eventuellement interferer.[Traduit par le journal] %ntrsduction (3) but little or no enhancement in measured Complexing reagents are often used to selective-c~~r r e n t .However, techniques that use rapid potenly shift the reduction potentials of metal ions. In a tial sweep rates such as cyclic voltammetry (4) or study of this effect using single drop square wave ~~c i l l o~o l a r o g r a~h~ ( 5 ) -or techniques which empolarography (SDSWP) it was observed that addi-ploy pulse waveforms such as normal (6, 7 ) or tion of common complexing reagents such as citric differential pulse ~olarography (DPP) (8)-produce acid or ethylene diamine to solutions both wave shifts and enhanced currents. In generCd(II) with chloride or sulfate salts as supporting "1. the faster the sweep rate Or the the caused cathodic shifts in the peak meaSUremetlt time after application of the pulse, reduction potential and no change or a decrease in the greater the enhancement. Qualitatively the the peak current. This is the expected behaviour. enhancement is caused by the Presence of excess H~~~~~~, the addition ofpicolinic acid (pyridine-2-electroactive species right at the electrode surface carboxylic acid) caused not only the predicted whi...

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