[Preparation and evaluation of 3,5-dinitrobenzoyl-bonded silica gel stationary phase for high performance liquid chromatography]

A new preparation method of 3,5-dinitrobenzoyl-bonded silica gel stationary phase (DNB) for high performance liquid chromatography has been developed by using N-(beta-aminoethyl)-gamma-aminopropyl-methyldimethoxy silane as coupling reagent. Its structure was characterized by elemental analysis, diffuse reflectance Fourier transform infrared spectroscopy and thermal analysis. The surface concentration of 3,5-dinitrobenzoyl ligand was 2.08 micromol/m2 according to the carbon content from elemental analysis. The chromatographic performance of the new packing was evaluated by using different solute probes, such as polycyclic aromatic hydrocarbons (PAHs), phenols, naphthalene derivatives, nitrophenol positional isomers and sulfonamides. The results show that comparing with ODS, DNB has weaker hydrophobicity and more versatile chromatographic properties. The charge-transfer between the dinitrobenzoyl ligand and the analytes plays a significant role in the separation of phenols and naphthalene derivatives. In addition, static electric, hydrogen-bonding and dipole-dipole interactions are responsible for the above separations and improve the selectivity of DNB for solutes. An advantage of DNB is that it is suitable for the separation of the basic compounds containing nitrogen atoms without capped process because the spacer containing nitrogen atoms can shield the residual silanols on DNB.