Chromatography
Reverse phased HPLC often uses methanol / water mixtures as the mobile phase. Since the polarity of water spans the same range from 25 to 205 °C, a temperature gradient can be used to effect similar separations, for example of phenols. The use of water allows the use of the flame ionisation detector (FID), which gives mass sensitive output for nearly all organic compounds. The maximum temperature is limited to that at which the stationary phase is stable. C18 bonded phases which are common in HPLC seem to be stable at temperatures up to 200 °C, far above that of pure silica, and polymeric styrene / divinylbenzene phases offer similar temperature stability. Water is also compatible with use of an ultraviolet detector down to a wavelength of 190 nm.
Read more about this topic: Superheated Water