Determination of Mobile Thallium in Soil by Flow Injection Differential Pulse Anodic Stripping Voltammetry

Abstract

A procedure for the determination of mobile thallium in soil has been developed. Free thallium(I) was extracted with deionized water, while the sorbed and exchangeable metal was extracted with 1 M ammonium nitrate. Thallium in extracts was determined by differential-pulse anodic stripping voltammetry in a flow-injection system with medium circulation. 0.05 M EDTA was the base electrolyte. The procedure was applied for the determination of mobile thallium in a sample of ground from a waste dump which was a potential source of thallium pollution. The total concentration of thallium in the sample was 17.9 mg g À1 . 3.97 AE 0.25% of total thallium was found to be water soluble and 12.4 AE 1.1% was sorbed and exchangeable. An attempt to determine the thallium bound to the carbonate fraction failed because of the high accumulation of interfering lead in this fraction. A single extraction cycle recommended by the literature was not sufficient to extract the whole thallium content of the fraction. Minor rivers of the area of the waste dump have a thallium concentration higher by two orders of magnitude than in reference rivers.

Optimizing the Differential Pulse Anodic Stripping Voltammetry Method With a Hanging Mercury Electrode for Thallium (I) Determination in the Presence of Lead (Ii) and Copper (Ii) for Application in Contaminated Soils

“…The influence of the following parameters on the response of the reduction current intensity for the electrodeposition of thallium on the HMDE was studied: deposition potential, deposition time, scan rate, and pulse amplitude, by starting from initial values as proposed by the AB074 Metrohm procedure (Dhaneswar and Zarparkar [1980], Lukaszewski et al [2003]) (deposition potential = -0.700 V, deposition time = 60 s, scan rate = 20 mV/s, pulse amplitude = 0.050 V). This was done in the presence of 2, 10, 20 and 25 mg/L Pb(II), and/or 2, 4 and 5mg/L Cu(II).…”

“…In order to separate as much as possible the Tl(I) signal from those of Pb(II) and Cu(II), the scan rate was varied keeping constant the amplitude pulse at 0.050 V (Dhaneswar and Zarparkar 1980, Metrohm 1993, Lukaszewski et al 2003. A lower amplitude produced too much noise, and higher amplitudes generated higher current intensities (Fig.…”

Indirect Anodic Stripping Voltammetric Determination of Tl(I) and Tl(III) in the Baltic Seawater Samples Enriched in Thallium Species

“…It is known that Cd 2 + , Sn 2 + and Pb 2 + form nonelectroactive complexes with EDTA [7,8] and DTPA [1]. Therefore, determination of thallium in the presence of even thousand-fold excess of interfering ions is possible.…”

“…The limit of quantification (LOQ) for this method is similar or even lower in comparison to inductively coupled plasma mass spectrometry (ICP MS) [1]. ASV allows to determine Tl(I) in digested plant tissues [1] or soil extracts [7] even of ng mL À1 level, when the supporting electrolyte contains EDTA or DTPA. When flow injection anodic stripping voltammetry (FI DP ASV) using 60 min deposition on mercury film electrode (MFE) is applied pg of Tl per mL of the solution can be detected [8].…”

Determination of Lead and Cadmium at Silver Electrode by Subtractive Anodic Stripping Voltammetry in Plant Materials Containing Tl

“…For analytical purposes the following reagents were used: 68% HNO 3 were diluted to obtain appropriate concentrations for the standard solutions of Cd, Pb and Tl employed in the experiments.…”