Differential electrolytic potentiometry with periodic polarisation. Part XXV. Direct and mark-space biased periodic current polarisation in acid-base titrimetry in acetic anhydride-acetic acid

Abdennabi, Abdalla M. S.; Bishop, E.

doi:10.1039/an9820701032

Cited by 9 publications

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“…The performance of the Ag-CNTs electrodes prepared under the optimum conditions was further investigated by comparing their performance to that of the bare silver electrodes during the micro titration of cyanide with silver nitrate using mark-space bias differential electrolytic potentiometry [6] [7] [22]. Figure 9 shows the results of titrating a volume of 10 µL of 0.05 M cyanide with a solution of 0.05 M silver nitrate.…”

Section: The Performance Of the Ag-cnts Electrodesmentioning

confidence: 99%

Carbon Nanotubes as Nanosensor for Differential Electrolytic Micropotentiometry

Amro¹,

Abulkibash²,

Atieh³

2014

AJAC

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Carbon nanotubes as nanosensor were synthesized on the surface of the silver electrode using floating catalyst chemical vapor deposition reactor. Acetylene gas was used as a carbon source, ferrocene as a source of the iron nanocatalyst and hydrogen as a carrier and an activate agent. Several runs were performed to find the optimum conditions that produce sensitive Ag-CNTs electrodes. The electrodes obtained at each run were characterized by SEM. The optimum conditions that produce sensitive Ag-CNTs were found to be at a reaction time of 15 minutes, reaction temperature of 700˚C, hydrogen flow rate of 25 ml/min and an acetylene flow rate of 75 ml/min. These optimum conditions were confirmed from the normal behavior of the resulting Ag-CNTs electrodes in the titration of 10 µL of chloride using dc differential electrolytic potentiometry. When conditions that differ from the optimum ones were applied in the preparation of the AgCNTs electrodes, abnormal titration curves were obtained. The superiority of the Ag-CNTs electrodes was demonstrated by the successful applications of these electrodes as an indicating system in the micro titrations of different volumes of cyanide solution with silver nitrate reach. By applying this technique a volume of 1.2 µL sample of cyanide was successfully titrated. The normal behavior of the Ag-CNts electrodes was compared to that of the normal silver electrodes which exhibit an abnormal behavior.

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Section: The Performance Of the Ag-cnts Electrodesmentioning

confidence: 99%

Carbon Nanotubes as Nanosensor for Differential Electrolytic Micropotentiometry

Amro¹,

Abulkibash²,

Atieh³

2014

AJAC

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Differential electrolytic potentiometric determination of caffeine in nonaqueous media

Abdennabi

Sultan

1993

Electroanalysis

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The application of direct current differential electrolytic potentiometry (dc DEP) to the titration of caffeine in acetic anhydride-toluene mixture has been investigated. A very stable low current source has been constructed to polarize the antimony electrodes. The behavior of these electrodes during the titration of caffeine has been examined. Caffeine in commercial samples like tea, Pepsi as a beverage and Prontopyrin, a proprietary drug, was extracted in chloroform and determined by dc DEP.KEY WORDS Caffeine, Electrolytic potentiomeuy, Antimony electrode.The technique of direct current Merential electrolytic potentiometry (dc DEP) consists of polarizing two identical electrodes with a heavily stabilized current and measuring the potential difference (AE) between them during the course of the titration. This technique offers an advantage over the classical potentiometry because it does not require a reference electrode. Moreover, the shape of the titratiDn curve will be in the form of a sharp peak whose tip is used for the precise location of the end point. The dc DEP technique has been applied to various types of titrimetric reactions in both aqueous [ 1-41 and nonaqueous [5-8] media using different types of indicating systems. Antimony metal-metal oxide electrodes are appropriate for acid-base reactions [l-31, while silver electrodes have been used mainly for precipitation reactions (4,6]. Platinum electrodes have been applied in oxidation-reduction reactions [9].Different types of nonaqueous solvents have been examined and found to be suitable for employing dc DEP technique. A mixture of toluene and methanol has been used for acid-base reactions [7]. Acetic acid has been used as a solvent for both oxidation-reduction reactions and precipitation reactions [6,9]. Propylene carbonate has been employed for oxidation-reduction reactions [ 101. Acetic anhydride, either alone or in conjunction with toluene, has been found to be a suitable medium for the titration of weak bases [ll-131. Several basic compounds have been titrated with perchloric acid which was dissolved in a mixture of acetic acid and acetic anhydride [ 51. Large drifts in the potentials of the employed antimony electrodes have been observed during the titrations of certain compounds like dimethylsulfoxide and caffeine. The differential curves of those compounds have been found to be poor and unsymmetrical [j].This communication describes the applicability of dc DEP technique for the titration of caffeine in acetic anhydride-toluene mixture. The advantage of using a very stable current source and its effect on the behavior of polarized electrodes is presented. The results of determining caffeine in commercial samples are also reported. mmmaThe Constant Current Source A constant current source which provides a stabilized current of the range of 100 n~-100 uA was constructed. This source consists of a dc power supply, a rectifymg and a filtering unit, and four integrated circuits. Figure 1 represents a dc power supply unit which is powered ...

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