Surprisingly, the exchange of isotopologues in the monolayer has not been studied using SERS spectroscopy yet. Some results were reported on the exchange of chemically different ligands , which proved the viability of SERS in this application. Outside of the ligand exchange context, there are scarce examples of works employing various isotopologues of a single compound and SERS spectroscopy. Those were used mainly for unequivocal proof of single-molecule detection , improvement of the detection limits of SERS-based analytical protocols or a facilitated vibrational assignment in a complex system with otherwise overlapping bands . Perera et al. studied the ability of thiol molecules to exchange citrate ligands, either perdeuterated or not, originating from the synthesis of gold nanoparticles into other adsorbates . Exchange of isotopologues may be tracked with a variety of methods, including radiometric detection , IR spectroscopy , and mass spectrometry , however, the literature lacks analogous reports in which SERS is employed as the detection principle.