Superheated water as a mobile phase

This project has focused on the applicability of using superheated water as an alternative eluent for use in reversed phase high performance liquid chromatography (RP-HPLC). A system based on instrumentation from gas chromatography (GC), HPLC, and supercritical fluid chromatography (SFC) was utilised with some success. Of particular importance was the stability of the column stationary phases commonly employed in RP-HPLC. The most popular phases based on alkyl bonded silica proved unsuitable due to excessive dissolution of the base silica at high temperatures. Nevertheless, two other phases—one a poly(styrene-divinylbenzene) material and the other a porous graphitic carbon—proved stable to temperatures as high as 240°C. At such temperatures compound stability was good, except for a notable case with nitrobenzene. The mechanism of elution remained reversed phase mode throughout, with polar solutes being eluted before non-polar ones. [Continues.]