336 was purchased from Thermo Fisher
Scientific (Merelbeke, Belgium). KBr (≥99%) and di-isobutyl
ketone (DIBK, >96%) were acquired from Acros Organics (Geel, Belgium).
Potassium iodide (KI) (≥99.5%) was bought from Honeywell Riedel
de Haën (Seelze, Germany). KSCN (>99%) and KNO3 (>99%)
were purchased from Chem-Lab (Zedelgem, Belgium). NaHSO4 (>93%) was acquired from Carl Roth (Karlsruhe, Germany). Water
was
always of ultrapure quality (Milli-Q water), deionized with a Merck
Millipore Milli-Q Reference A+ system. All chemicals were used as
received, without any further purification.