Use of Adsorption Properties of Resin for Water Sample Preparation in Voltammetric Determination of Se(IV) Using Bismuth Microelectrode

This paper proposes a simple, environmentally friendly, and efficient procedure for preparing natural water samples for the voltammetric determination of trace amounts of Se(IV). The method is based on premixing a sample with Amberlite XAD-7 resin at 50 °C. The composition of the 10 mL solution consists of the sample to be analysed, 0.1 mol L^-1 of acetate buffer at pH = 4.0, and 0.5 g of Amberlite XAD-7. After 2 min of stirring, a voltammetric measurement is carried out using a fixed bismuth microelectrode using the following potentials: -2.5 V for 2 s and -0.55 V for 30 s. The voltammetry is recorded by varying the potential from -400 mV to -1000 mV. An undisturbed Se(IV) signal is obtained in the presence of 10 mg L^-1 of Triton X-100, 5 mg L^-1 of SDS, 10 mg L^-1 of CTAB, 5 mg L^-1 of Rhamnolipid, 5 mg L^-1 of HA, 10 mg L^-1 of FA, and 2 mg L^-1 of NOM. The validity of the developed procedure is checked by analysing the certified reference materials SPS-SW1 (surface water) and TM-25.5 (Lake Ontario water) additionally enriched with surfactants and humic substances.