The change in the concentration of sulphate ions in aqueous solution also results in linear dependence between the logarithm of the ion concentration and oxidation reactions potential of 5FSQC6 (Fig. ). The slope of the curve is close to 0 mV per decade for the first oxidation reaction, (-43 ± 5) mV per decade for the second reaction and (-36 ± 4) mV per decade for third reaction. For the second and third oxidation reactions, the slope of the curve is not exactly the expected value obtained from the Nernst-like equation (Eq. 3). In these instances, the redox reaction is accompanied by the transfer of sulphate from the aqueous to the organic phase and as the calculations and previous studies show , the stoichiometry can be complicated. It is presumed that placing an electrode with an organic droplet in the aqueous phase can result in the complexation of potassium ions by the crown ether, building the ion pair receptor under study. The first peak, which is a low-current shoulder on the main peak, that does not involve the transfer of sulphate, might be associated with the expulsion of the potassium ion or some other process. Transfer of both fluoride (Fig. .) and sulphate (Fig. .) ions occurs at lower potentials (for sulphate, the transfer potential is lower around 90mV, for fluoride: 50mV) when the 5FSQC6 receptor is used than for CF3SQC6. According to the DFT calculations, the binding is stronger to the CF3SQC6 (Table .