Diamond and diamond containing composites gained strong attention of chromatographers in the last decade [1]. There are many advantages of this carbon allotrope including excellent mechanical, thermal and hydrolytic stability, the highest known thermal conductivity in combination with extremely low thermal expansion coefficient. The combination of these properties makes diamond the most promising material for the use in HPLC/UPLC. The separation selectivity of diamond is another intriguing characteristics of this carbonaceous material.
This presentation will review the recent achievements in the preparation and characterisation of adsorption and chromatographic properties of micro dispersed sintered detonation nanodiamonds (MSDN) and of micro particles of diamond of static or high pressure/high temperature synthesis (HPHT). MSND fraction with average particle size 3-4 microns, specific surface area 190 m2/g and bimodal pore size distribution was used as a column (150 x 4.0 mm ID) packing after additional purification and fractionation on size. The surface of MSND contains carbon in sp2 and sp3 forms and significant amount of various functional groups (-COOH, -OH, -COH etc.). HPHT particles of average size 2.5-4.0 microns having specific surface area ca. 3.0 m2/g are used as a packing material of a bigger column (125 x 7.0 mm ID) for the comparison.
The regularities of the retention of polar and non-polar organic molecules and inorganic ions are studied with both types of diamond particles under various separation conditions (RP and NP HPLC, ion-exchange, HILIC ). Both HPHT and MSND demonstrated the distinctive ability to retain polar organic molecules having labile proton in a molecule (phenols, nucleotides, and aromatic acids) as well as inorganic ions.