Volume: 3, 2024
3rd International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland:
ENVIRONMENT – PLANT – ANIMAL – PRODUCT
Abstract number: E006
DOI: https://doi.org/10.24326/ICDSUPL3.E006
Published online: 24 April 2024
ICDSUPL, 3, E006 (2024)
Voltammetric determination of tungsten in environmental waters rich in organics matrix
Marzena Fialek1*, Małgorzata Grabarczyk1
1 Department of Analytical Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, 20-031 Lublin, Poland
* Corresponding author: marzena.fialek@mail.umcs.pl
Abstract
This work describes the quantification of tungsten in environmental water samples using the cathodic stripping voltammetry. In the voltammetric procedure, eco-friendly solid bismuth microelectrode as a working electrode, an Ag/AgCl (saturated NaCl solution) reference electrode, and a Pt counter electrode was applied. The standard measurements were run in a solution containing 0.1 M acetic acid and 1.5 × 10−5 M Bi(III). Before each measurement, the microelectrode surface was activated by applying a potential of –1.8 V for 1 s, which increased the sensitivity of tungsten determinations. After this stage, preconcentration of tungsten as W(V) was carried out at –0.5 V for 20 s. Then, as a result of changing the electrode potential in the range from –0.6 V to –0.9 V, W(V) was reduced to W(III) and an analytical signal was recorded. The aim of the presented procedure is the quantification of W(VI) in environmental water samples, so investigation of the effect of organic matter on the intensity of the W(VI) signal was needed. One of the most important components of organic matter present in natural water samples are humic substances. Therefore, different kinds of humic substances, such as: humic acid (HA), fulvic acid (FA) and natural organic matter (NOM), were examined in this studies. It turned out that the HA, FA and NOM, in their concentrations equal to 2 mg L−1 causes a reduction of the voltammetric signal of W(VI) by about 25%, 75%, and 90%, accordingly. To eliminate these interferences, we decided to include an additional stage in the method of tungsten determination, which consisted in introducing 0.1 g Amberlite XAD-7 resin into a voltammetric cell and mixing the sample with this resin for 2 minutes before the voltammetric measurement. In these tests, the solution contained tungsten at a constant concentration and various amounts of selected humic substances. The concentration of humic substances was changed from 0.5 to 10 mg L−1. It was founds that, owing to the pre-mixing sample with resin, the tested humic substances did not affect the analytical signal even in the presence of 10 mg L−1 of all tested humic substances, i.e. HA and FA. This is also corroborated by the W(VI) recovery tests (salvage values from 90 to 108.7% with RSD in the scope from 2.9 to 4.9%) carried out in various real samples and certified reference materials with complex matrix and rich elemental composition.
Keywords: cathodic stripping voltammetry, eco-friendly detection of tungsten, environmental water samples, Amberline XAD-7 resin
How to cite
M. Fialek, M. Grabarczyk, 2024. Voltammetric determination of tungsten in environmental waters rich in organics matrix. In: 3rd International PhD Student’s Conference at the University of Life Sciences in Lublin, Poland: Environment – Plant – Animal – Product. https://doi.org/10.24326/ICDSUPL3.E006