The reactor was constructed of stainless steel with an internal volume of 20 mL, as shown in Fig. . 1/8 in. O.D. PEEK (polyether ether ketone) tubing was used to flow the para-enriched hydrogen gas, and 1/16 in. O.D. 0.5 mm I.D. PTFE (polytetrafluoroethylene) capillaries were used for all solution flow. These tubes were connected to the reactor via 1/4-28 PEEK fittings (part numbers P-249 and P-349, IDEX LLC, Oak Harbor, U.S.A.), and to the gas flow-control manifold via Swagelok fittings (Swagelok, Frankfurt, Germany). The reactor was wrapped in two heater mats (part number 798-3753, RS Components, Corby, U.K.), and these were connected to a power supply, with the current set to heat the reactor to 85°C.