A Prussian blue-based reactive electrode (reactrode) for the determination of thallium ions

Abstract

A reactive electrode (reactrode) made of Prussian blue (PB), graphite and paraffin can be used for a selective determination of thallium ions down to a concentration of 2. 10(-8) mol 1(-1). The working principle of the reactrode is that thallium ions can be pumped into Prussian blue during alternating oxidation-reduction cycles. After a preconcentration of thallium ions in PB, the voltammetric determination follows as usually in anodic stripping voltammetry, i.e. the thallium ions are reduced to thallium metal which is subsequently oxidized to give the anodic stripping signal. The peculiarity of the Prussian blue-thallium system is that the thallium ions are situated in the holes of the PB matrix. When reduced to metallic thallium, they are substituted by potassium ions. Cd(2+), Fe(3+), Zn(2+), Cu(2+) and Ni(2+) do not interfere up to a hundredfold excess, NH(4)(+) does not interfere up to a thousandfold - and Bi(3+) up to tenfold excess. The interference by Pb(2+) can be suppressed with EDTA.

A New Selective Chromogenic Reagent for the Spectrophotometric Determination of Thallium(I) and (III) and Its Separation Using Flotation and the Solid-Phase Extraction on Polyurethane Foam

“…The sample was then dissolved in hot HNO3 until near dryness, adjusted to pH 1.0 -1.5 using HNO3 and NaOH solutions and completed to 100 cm 3 . Another sample was similarly spiked and dissolved in hot nitric acid, then oxidized with 0.5 cm 3 bromine water, heated until near dryness and completed to 100 cm 3 . Flotation and SPE techniques were again applied on the samples, as described above.…”

“…Effect of the concentration of PET and the shaking time. The adsorption isotherm of PET dissolved in acetone/water 1:3 solvent (volume 50 cm 3 and the shaking time 30 min) on 0.1 g PUF showed that PET (Fig. 2) is quantitatively leached with PUF and reaches saturation with 15 µmol g -1 at a concentration of 0.3 mmol dm -3 .…”

Simultaneous separation and determination of Tl(I) and Tl(III) by IC-ICP-OES and IC-ICP-MS

“…Atomic absorption spectrometry (Ivanova et al, 1997), in particular ETA-AAS is widely used for the determination of Tl, due to its high sensitivity. Electrochemical methods (Bohrer and Schwedt, 1998;Kahlert et al, 1996 andDiewald et al, 1994), as well as spectrophotometric methods (Vartak and Shinde, 1998;Namboothiri et al, 1991;Mihajlovic andStafilov, 1996 andHafez et al, 1996) have also been used for Tl determination. In addition, fluorimetric methods (Perez-Ruiz et al, 1996), liquid scintillation counting (Rajesh andSubramanian, 1992 and1994), and isotope dilution mass spectrometry (Oliver and Klaus, 1999) have been reported for Tl determination.…”

Rhodium-Prussian Blue modified carbon paste electrode (Rh-PBMCPE) for amperometric detection of hydrogen peroxide

“…The calculated value is higher than others reported in the literature. 6,9,10,12,13,16,34,35 This was expected, since we used a pre-concentration step and higher deposition times, a total of 6 min during 3 deposition steps.From Figure 1 it is also possible to see that no peaks were recorded, with an unmodified carbon paste electrode, in the same potential range from -0.4 V to + 0.6 V. It is possible that rhodium (III) can form binuclear species (Rh 2 O 6 3+ …”

“…In these cases Nafion, 8,10,14,17,30 poly (ophenylenediamine), 21 polypyrrole/poly (o-phenylenediamine) 23 and poly (o-diaminebenzene) 18 polymers have been used to immobilize the enzyme and eliminate interferences from ascorbic and uric acids. Chemical preparations were also described and involve the immersion of the working electrode in aqueous modifier solution, 5,6,19 the mixture of Prussian Blue (chemically synthesized) with graphite and paraffin 34 or hydrocarbons 33 to produce modified carbon paste electrodes and the dispersion of Prussian Blue, supported on graphite, into methyltrimethoxysilane-derived gels to get a renewable three-dimensional modified electrode. 35 PB can be reduced to Prussian White (Everitt salt) around 0.2 V or oxidized to Berlin Green around 0.9 V. Generally, the films are not stable during successive cycles around of the two reversible couples of PB, but the effect is more pronounced at 0.9 V, 6,25 perhaps because Fe 3+ ions are lost to the solution during this process.…”