The fight against climate change, the increasing global energy demand, the necessity of further safety improvements and the accumulation of nuclear waste are all together strong reasons for the development of the fourth generation of nuclear reactors. Via the MYRRHA-project, scientists at SCK•CEN are working on these topics and more. MHYRRHA will be an accelerator driven nuclear reactor that can be loaded with fuel enriched with transuranic elements. This reactor will be operating with the lead-bismuth eutectic as coolant. Due to corrosive effects, a significant amount of nickel can be dissolved from fuel cladding and structural steels in the coolant. That brings up the necessity of finding a solution to measure its concentration in the liquid eutectic and to remove it. Therefore, the principle of the potentiometric concentration determination of metal impurities was tested in this work. Based on the Nernst equation, formulas were derived allowing the deduction of the nickel concentration in the lead bismuth eutectic and later in bismuth. Comparing the chemical stabilities of the different experimental components showed the instability of some key compounds and explains why the use of nickel chloride as electrolyte rules out a nickel sensor in the aforesaid eutectic. To prove the feasibility of the potentiometric concentration determination of nickel in liquid metal, the work was continued in molten bismuth. Thanks to two long-term experiments, the principle was finally proven feasible even if there remain some unexplained deviations. Besides that, the thermoelectric potential between the used nickel electrode wire and molybdenum wire was measured. Lastly, explanations for these discrepancies were searched in the purity of the used chemicals, the temperature gradient in the furnace and the solubility data used. Contrary to the indication in the title, the nickel extraction could not be performed because of the mentioned reasons.