In order to investigate the effect of continuous sample flow, a syringe pump (Aladdin Syringe ONE Programmable Syringe Pump AL-1000, World Precision Instruments, Hitchin, UK) was used to provide a steady flow of solution. At its lowest setting, the flow was 0.375 mL min -1 , which corresponded to a residence time of approximately 2.4 s within the sample cuvette when assuming plug flow. The syringe was contained by a metal tube which was wrapped with a heating coil (SRT051-040LSE, silicon rubber tape, Omega Engineering, Manchester, UK). This ensured that the heat provided by the heating coil was evenly distributed and single-use syringes could easily be replaced between measurements. Further heating coil was wrapped around the transfer tube all the way to the inlet of the crystallisation cell. This made it possible to control, and keep the temperature constant both inside the syringe and the transfer tube.