ИСТИНА

Modern chromatography encounters constantly growing demand for column performance and minimisation of analysis runtime. Generally, increase in performance can be achieved at higher temperatures and higher flow rates, as well as by using stationary phases with smaller parcticle sizes. These requirements result in booming interest to ultra high pressure and high temperature separations. Diamonds have good thermal stability and thermal conductivity, mechanical stability at any pressures, stability in presence of any solvents and under any pH. These advantages make diamond a very promising stationary phase for a variety of chromatographic applications under extreme pressure and temperature, as compared to conventional silica based phases. Diamonds and nanodimaonds recently have become easily accessible and relatively cheap because of development of the new synthesis technologies, which enables their industrial scale applications. A new approach for utilising synthetic diamond and nanodiamond as a stationary phase for HPLC will be introduced in this presentation. Combination of packing in gravitational field with subsequent pressure packing at high temperatures was applied in order to obtain very dense and more uniform diamond beds. This resulted in efficiency over 100000 plates/m, which can be considered as a breakthrough for diamond packed columns. Due to non-porous structure of diamond and its very low resistance to mass transfer coefficient between mobile and stationary phase, it was possible to maintain high efficiency at flow rates far above optimal. Influence of mobile phase, flow rate and temperature on the column performance and selectivity was investigated; columns were examined at pressures up to 1000 bar and temperatures up to 140°C. It was established that two main mechanisms are responsible for retention of analytes, including hydrogen bonds and hydrophobic interactions. The separation of model mixture of 6 compounds within 4 minutes in isocratic conditions was demonstrated.